DENTAL FLUOROSIS IN GOZO · DENTAL FLUOROSIS IN GOZO A Dissertation Submitted in Part-FulfIlment of...
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DENTAL FLUOROSIS IN GOZO A Dissertation Submitted in Part- FulfIlment of the Requirements for the Degree of Masters of Science in Public Health Medicine of the University of Malta Ethel Vento Zahra August 2007
Transcript of DENTAL FLUOROSIS IN GOZO · DENTAL FLUOROSIS IN GOZO A Dissertation Submitted in Part-FulfIlment of...
DENTAL FLUOROSIS IN GOZO
A Dissertation Submitted in Part- FulfIlment of the Requirements for the Degree of Masters of Science in
Public Health Medicine of the University of Malta
Ethel Vento Zahra
August 2007
Declarations
I, the undersigned, declare that this dissertation is my original work, carried out under the
supervision of Dr Pauline J. Vassallo BChD, MSc (Lond.), DDPH, RCS (Eng.), MBA
(Warwick), Consultant in Dental Public Health.
Ethel Vento Zahra
I, the undersigned, declare that in my opinion this dissertation is good enough to warrant
at least a pass by the MSc Public Health Examination Board.
Pauline Vassallo
Dedication
To my family and friends. Thanks for all the love and support.
You're all special and irreplaceable!
The successful completion of this dissertation would not have been possible
without the encouragement and help of several people.
I would like to express my sincere gratitude to my supervisor Dr Pauline J.
Vassallo B.Ch.D, MSc (Lond.), DDPH, RCS (Eng.), MBA (Warwick), Consultant
in Dental Public Health, for her patience, support and guidance with this project.
I would also like to thank Dr Neville Calleja MD, MSc, MSc (Lond), DLSHTM
Grad. Stat., Principal Medical Officer in Medical Statistics within the Department
of Health Information, for his immense patience and assistance in the statistical
analysis of the study results.
I am immensely grateful for the assistance given to me by the dental hygienists at
Gozo General Hospital, in particular Mr. Paul De Brincat and Mr. Martin Vella
who acted as my guides and scribes. Without them I would probably still be lost in
Gozo, vainly trying to fmd the next school on my list.
My fmal thanks go to all my family and friends who, in their own various ways,
have been supporting me patiently throughout this course of study.
Ethel Vento Zahra University of Malta
August 2007
SUMMARY
The aim of this study was to examine the levels of dental fluorosis in 5 year old and 12 year
old school children, so as to evaluate if dental fluorosis in Gozo is presently a public health
problem. A path finder survey carried out in 1986 by Moller suggested that dental fluorosis
was a public health problem since values of >0.6 using Dean's index were recorded.
These exceeded the threshold value of 0.4-0.6. However, Moller himself questioned the
results due to the possibility that other enamel opacities were included as dental fluorosis.
The objectives of this study were:
1. To determine prevalence of fluorosis in the deciduous dentition in Gozo, which
has never been determined previously.
2. To establish how large a public health problem dental fluorosis currently is in
both the deciduous (in 5 year oIds) and the permanent dentition (in 12 year olds)
in Gozo.
3. To determine how aware the 12 year old Gozitan children are about the aesthetic
changes to their upper central incisors, associated with dental fluorosis.
4. To serve as a comparison for future studies which may be carried out to determine
the effect of polished water on fluorosis prevalence in the same population.
All 5 year old and 12 year old children with a signed consent form, present at the school on
the day of the visit were examined clinically, and observations were recorded using the TF
Index. Intraexaminer reliability was tested. Locality of residence in the case of 5 year olds
and locality of residence up to 6 years of age in the case of the 12 year old children was
recorded. The 12 year old children were also asked a question to detennine awareness of
aesthetic changes associated with dental fluorosis. The data collected was analysed using the
SPSS software package.
The results show negligible dental fluorosis in the 5 year old age group. 13.8 % of the 12
year olds had marks attributable to dental fluorosis on their upper anterior teeth, out of
which only 4% have mild to moderate fluorosis (fF scores 3 to 5), the worst result recorded.
Only 0.86 % of all the 12 year old children examined were aware of marks attributable to
fluorosis on their upper anterior teeth.
The difference in fluorosis between localities is statistically significant (p = 0.(05). No
correlation (p = 0.68) was found between mean fluoride concentrations (1994 to 2000) for
individual localities and mean dental fluorosis levels reported in the respective localities.
The conclusions drawn from this study are that:
• Dental fluorosis prevalence in Gozo is currently: negligible in the deciduous
dentition; low and mild in the permanent dentition. Therefore dental fluorosis in
Gozo is currently not a public health problem.
• The 12 year old children are not aware of the aesthetic changes associated with
dental fluorosis.
• There is a significant difference in the prevalence of dental fluorosis in the
permanent dentition when analysed by locality.
• The systemic source of dental fluorosis which is present in Gozo is not singularly
tap water, as was previously assumed.
Contents
Table of Contents ................................................................................... i List of Tables ........................................................................................ iv List of Figures ....................................................................................... iv
Chapter 1
1.1 1.1.1 1.1.2 1.1.3 1.1.4 1.1.4.1 1.1.4.2 1.1.4.3 1.1.4.4 1.1.4.5 1.1.4.6 1.2 1.3 1.3.1 1.3.2
Chapter 2
2.1 2.11 2.2 2.2.1 2.2.2 2.2.3 2.3 2.4 2.5 2.5.1 2.5.2 2.6 2.6.1 2.6.2 2.6.3 2.6.4
Introduction ........... , ........................................................... 7
Background Infonnation: Gozo General Country Infonnation Politics Education Health Care System in Gozo Overview Dental Care System Human Resources Financing General Health Oral Health Water Supplies Aims and Objectives Aim Objectives
Literature Review .............................................................. 20
Introduction Fluorides in the Environment The Chemistry of Fluoride in Water Fluoride Vehicles Population Measures Individual Measures Professionally Applied Measures Fluoride Usage Fluoride as a Caries Preventive Agent Effect of Fluoride - Mechanism of Action Pre- Eruptive Effect Post- Eruptive Effect Fluoride and the Body Fluoride Intake by Man Absorption, Retention and Excretion Fluoride in Teeth and Bone Excretion
2.7 2.7.1 2.7.2 2.S 2.S.1 2.S.1.1 2.S.1.2 2.S.1.3 2.S.1.4 2.S.2 2.S.3 2.9
Chapter 3
3.1 3.2 3.3 3.4 3.5 3.5.1 3.5.2 3.5.3 3.5.4 3.6
Chapter 4
4.1 4.1.1 4.1.2 4.1.3 4.2 4.3
Chapter 5
5.1
Fluoride Toxicity Acute Toxicity Chronic Toxicity Fluorosis Dental Fluorosis Indices of Dental Fluorosis Aesthetic Perceptions of Fluorosis Treatment Options for Dental Fluorosis Evidence of Dental Fluorosis in Gozo so Far Skeletal Fluorosis Other Effects Conclusion
Methodology ...................................................................... 59
General Design of the Study Literature Review Examiner Training Study Population Data Collection Fluorosis Data Intraexaminer Reliability Aesthetic Awareness Data Public Water Supplies Analysis and Presentation of Data
Results ............................................................................. 65
Introduction
Dental Fluorosis Results obtained for Fluorosis in 5 year old Gozitan School Children Results obtained for Fluorosis in 12 year old Gozitan School Children Results obtained for Intraexaminer Reliability Aesthetic Awareness Fluoride Availability
Discussion and Conclusions ................................................... 75
Fulfilment of the Study Objectives
ii
5.1.1
5.1.2
5.1.3 5.1.3.1
5.1.3.2 5.1.4
5.2
Chapter 6
Determination of Prevalence of Dental Fluorosis in the Deciduous Dentition How large a Public Health Problem is Dental Fluorosis in Gozo Currently? Monitoring Trends of Dental Fluorosis How will the New Water Supply System affect Oral Health in Gozo in the Future? Impact on Dental Caries Determination of Aesthetic Awareness of Changes Associated with Dental Fluorosis in the 12 year old children Limitations of the study.
Recommendations ............................................................... 87
Appendix 1 Definitions ............................................................................ 90 Appendix 2 Request for Research in State Schools .............. , ....................... 91 Appendix 3 Letter from University Research Ethics Committee ..................... 93
References ....................................................................................... 94
iii
LIST OF TABLES
1 Gozo Water Quality Zones ............................................................... 15 2 Tentative estimates of a number of people throughout the world using various .. 26
types of fluoride therapy and preventive measures. 3 Degrees of potentially toxic ingestion offluoride ..................................... 37 4 Primary teeth chronology ................................. '" ............................ 40 5 Permanent teeth chronology .............................................................. 40 6 Comparison of characteristics of Dental Fluorosis and Non- Fluoride EnameL. 53
Opacities. 7 Clinical criteria and Scoring for the TF Index ......................................... 62 8 Levels of Dental Fluorosis in 12 year old children in 1986 .......................... 66 9 Fluoride levels in water by locality in Gozo ........................................... 74
LIST OF FIGURES
1 Map of the Maltese Islands ............... " ......................................... , .... 7 2 Map of Gozo Localities with respective population size according to 2005 ........ 9
Census. 3 DMF-Tin 12 year old children in European Countries for 2004 ................... 14 4 21 US cities study: Fluorosis at age 12-14, according to natural water fluoride .. 23
concentration. 5 Mild Fluorosis .............................................................................. 43 6 Mild to Moderate Fluorosis .............................................................. 43 7 Moderate to Severe Fluorosis ............................................................. 44 8 Severe Fluorosis ....................................................... , ..................... 44 9 TF scores in 5 year old Gozitan School Children ................. " ................... 68 10 TF scores in 12 year old Gozitan School Children .................................... 69 11 Mean TF Scores with their confidence intervals by Locality ......................... 70 12 Map ofGozo showing Mean TF scores by Locality ................................... 71 13 Graph showing correlation between Fluoride concentration and TF scores by ... 73
locality. 14 Breakdown of response as to use of toothpaste from the National Oral Health ...... 80
Survey of the Maltese Islands carried out by Portelli and Vassallo in 2004. 15 DMF-TinS and 12 year olds against Fluoride in water in the Maltese Islands ...... 82
iv
CHAPTER 1 INTRODUCTION
1.1 BACKGROUND INFORMATION: GOZO
1.1.1 GENERAL COUNTRY INFORMATION
The Maltese archipelago consists of three inhabited islands; Malta, Gozo, Comino (which is
largely uninhabited) and two other uninhabited islands (Fig. 1). They lie in the middle of the
Mediterranean sea with Malta 93 kilometres south of Sicily and 288 kilometres north of Africa
with a total area of 316 square kilometres, (Malta 246, Gozo 67, Comino 2.7).
o I o
ed#erranean Sea
<1 8km I
4
' .
Med terranean Sea
,.,. Marsaxlokk. J,
~_.~~Bbbuga .~ ~} ~"--"'''''-,.
C
Filfl8
Figure 1: Map of the Maltese Islands.
7
The population of the Maltese islands at the end of 2005 was estimated at 404,039, with 31,
031 living in Gozo and 8 in Comino. The population is increasing at a steady rate and it is
projected that by the year 2025 it will exceed 418,000 people. Malta has a population density
of 1,513 residents per square kilometre whilst Gozo and Comino have a population density of
452 residents per square kilometre. (NSO 2005)
Compared to the EU, Malta's population is still relatively 'young'. The proportion of the
population under 25 years of age is 31.5 per cent, compared to 29.1 per cent across the EU.
However, 20.3 per cent of the Maltese population is aged between 50 and 64 years, this
being significantly higher than the EU average of 17.9 per cent Hence, within the next ten
years or so, most of the persons within this age cohort will be over 65 years. Assuming that
current socio-demographic trends continue in the future, the main characteristics being a
declining fertility rate and a low immigration intake of younger persons, a steady increase
in the old-age-dependency ratio is expected in the coming years. (NSO 2005)
The climate is warm, with mild wet winters and hot dry summers. There is no fog, snow or
frost Rain falls only for short periods, generally between September and April, and averages
578 mm a year. The average winter temperature is 14 degrees centigrade, whilst in the
summer it is 32 degrees.
1.1.2 POLmCS
Politically, Gozo and Comino form one of the thirteen electoral districts of the Republic of.
Malta. Five representatives are elected to the Maltese parliament, and to better look after
the Gozitan people's interests, one of these is always a central government cabinet minister.
8
Besides, each of the fourteen localities or village communities has their own local council
and therefore their mayor. A map of Gozo subdivided into the fourteen localities and their
respective populations is shown in Figure 2.
.GHARB POp!Laton: 1.195
·ZEBBUGAND MARSALFORN Popli'ator.: c.n3
.GHASRI Popu:atDn: 398
• SAN LAWRENZ
·XAGHRA Poptrat:on: ~.C23
-KERCEM • NADUR
PODu!aton: 'i.S&:. . "RABAT (VICTORIA)
Popu:atcon: 6.832
-FONTANA Populaton: 896
• MUNXAR AND XLENDI Popu:aoon:834 • XEWKlJA
·SANNAT Popu'at'Of1: 1.832
• GHAlNSIELEM Popu'at-on :2.671
+QAlA Popt;!at'on: 1.727
Figure 2: Map of Gozo Localities with respective population size according to 2005 Census
1.1.3 EDUCATION
A comprehensive state system provides all levels of education, free at the point of delivery.
This system is complemented by schools run by the church. There are no schools run by
private concerns in Gozo. Schooling is compulsory between the ages of 5 and 16. State
primary schools are found in most towns and villages while all the secondary schools can be
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found in Rabat, the capital city. The data from the 2005 census shows that the illiteracy rate in
Gozo was 11.24%.
1.1.4 THE HEALTH CARE SYSTEM IN GOZO
1.1.4.1 OVERVIEW
In The Maltese Islands, there is a comprehensive national health service that is available to all
Maltese residents and is entirely free at the point of delivery. The Government health services
are funded from general taxation. All residents have access to preventive, investigative,
curative and rehabilitative services in Government health centres and hospitals.
The Government's health centre system works side by side with a thriving private sector.
Secondary and tertiary care is provided principally from two public general hospitals, one in
Malta and one in Gozo, and other supporting specialized hospitals (Oncology, Psychiatric and
Geriatric). There are also two private hospitals, one of which has a branch in Gozo but which
does not supply dental care.
Currently only about 10010 of manpower resources are allocated to preventive examinations,
education and health promotion (Human Resources Department Ministry of Health).
However, several preventive programmes are run on a national scale, such as the free
immunization programme, which covers a wide range of illnesses.
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1.1.4.2 DENTAL CARE SYSTEM
Dental care is provided within the national health system provided by the Government to all
citizens on the basis of equity. There is ease of access to all sectors of the community
irrespective of means in respect of all urgent dental care as well as diagnostic care, preventive
care and oral surgery (Department of Health, Malta 1986). Those who qualitY on a means test
(low income groups), and hospitalized patients are eligible for free restorative care. In addition
children aged between 5 and 15 years enjoy free comprehensive dental care. In Gozo all dental
care provided by the government is carried out at Gozo General Hospital.
1.1.4.3 HUMAN RESOURCES
At present in Gozo there are two dental surgeons employed by Gozo General Hospital. There
are 7 private dental clinics and 12 registered dental surgeons in Gozo. There has been some
level of loss of personnel due to migration to other European countries but not to the extent
that the dental sector in Malta has been affected. This has become an issue due to the disparity
in working conditions between different European countries.
1.1.4.4 FINANCING
Provisional estimates for 2006 indicate that Malta's Gross Domestic Product stood at Lm 2.1
billion (€4.9 billion), or Lm 5,176 (€l2,058) per capita. 8.8% of GNP was spent on healthcare
in 2004. An estimate ofO.4 % of GNP was spent on Dentistry.
11
1.1.5 GENERAL HEALm
The health of the Maltese population compares favourably, in broad tenns, with that of other
Western European countries as measured by international indicators such as the WHO's
European Regional Health Indicators (Health Vision, 2000). Infant mortality rate is 3.82 per
1000 live births (2007) and maternal death is a rarity.
There has been a sharp drop in the standardized death rate from all causes since the early 80's.
In the case of premature deaths the rate has fallen below the EU average (Department of
Health, 1995).
The major contributor to mortality and morbidity in Malta and Gozo for the past four decades
has been circulatory disease, 44.3% of deaths in 2005, many due to coronary artery disease
and stroke. Even though the rate is below the European average, it is still well above that of
many neighbouring Mediterranean countries.
Both genetic and lifestyle factors probably contribute to this situation. Risk factors such as
diabetes, obesity, hypertension, and lack of exercise, are all highly prevalent in the Maltese
Islands. Significant differences now exist between the Maltese nutritional pattern and the
traditional 'Mediterranean diet' (Department of Health, 2(05).
Malignant neoplasms also dominate the mortality data (26.8% in 2(05). In men, the leading
causes of death were cancer of the lung, digestive system and prostate, while in women the
commonest killers were cancer of the breast, the colon, the pancreas and the lung (Department
of Health, 2005).
Other significant causes of mortality are due to respiratory system diseases, diabetes and other
metabolic diseases, digestive system disease and accidents (Department of Health, 2(05).
12
Infectious diseases are no longer common in the Maltese islands. Various types of viral
hepatitis are endemic, though tuberculosis and measles are on the decline. mv infection
prevails though not in alanning figures. It is estimated that there are about 206 seropositive
mv individuals and cumulative notification of AIDS from 1986 to 2003 is around 47.
1.1.6 ORAL HEALTH
The prevalence of dental caries is low. The mean DMF-T (Decayed, Missing and Filled Teeth)
of the Maltese Islands in 12 year-old school children is 1.3 with the DMF-T being 1.4 in Malta
and 1 in Gozo. Thus the Maltese Islands have achieved the WHO Goal of a DMF-T of 3 or
less and the National Goal of a DMFf of 2 or less. The treatment ratio for 12 year old school
children (filled teeth in relation to decayed and filled teeth) has improved from 0.13 in 1987 to
0.44 in 2004. Currently the treatment ratio is higher in Malta (0.45) than in Gozo (0.36)
(portelli and Vassallo 2004).
The difference between Malta and Gozo is more marked in the 5 year old children than in the
12 year old children. The mean DMF-T in 5 year old school children is 2 with a DMF-T of 2.4
in Malta and 0.7 in Gozo. The WHO goal of having 50% of5 year old school children caries
free has been met, but the National Goal of having 60% of 5 year old school children caries
free has not been met. The treatment ratio for the 5 year old children is very low, with 5.2% of
decayed deciduous teeth being filled in Malta and a negligible amount being filled in Gozo
(portelli and Vassallo 2004). Figure 3 shows a comparison ofDMF-T values for 12 year old
children in European countries for the year 2004. This shows that the DMF-T value for Malta
(1.4) is well below the European mean of 1.93.
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30% of 12 year old school children have poor oral hygiene. Only 5% had no plaque and
therefore good oral hygiene (portelli and Vassallo 2004). Data on levels of periodontal disease
are less recent with the only data available being from the 1987 pathfmder survey carried out
by Moeller which gives the periodontal status in 35-44 year old persons. This data shows a
high prevalence of poor oral hygiene with 78.3% of the sample studied having presence of
calculus, 17.1 % having shallow periodontal pockets and 2.1 % having deep periodontal
pockets. Although the situation of oral hygiene is improving, this remains a problem. The
prevalence of oral malignant lesions has always been low and is stable at 0.1 %
(Histopathology Department SLH).
UK Sweden
Spain
Slovenia
Romania
Portugal
Poland
Netherlands
Malta
Lithuania
Latvia
Italy
Ireland
Iceland
Hungary
Greece
Germany
France
Finland
Denmark
Czech Rep
Cyprus
Bulgaria
Belgium
Austria
0.00
I
I
0.50
0.80
1.00
1.3
I 1.50
1.00
1.30
1.13
1.10 I
1.50
.98
1.23
1.20
0.80
1.14
1.1 0
I 1.04
1.00 1.50
I
1.70
3.50
2. 0
3.50
3.30
2.20
2.50
I 3.03
2.00 DMF-T 2.50 3.00 3.50
Figure 3: DMF -Tin 12 year old children in European Countries for 2004. From the Database o/Oral Health Care in Europe (CECDO).
4.10
4.00
14
4.50
1.2 WATER SUPPLIES
The Water Operations Unit is responsible for all distribution and ground water operations in
the Maltese islands. These responsibilities include the Water Quality Zones and the
Distribution Control Section. The water supply network is divided into twenty Water Quality
Zones in Malta and Gozo. Each zone is linked to a particular reservoir which is numbered the
same as the Water quality zones. There are five Water Quality Zones for Gozo (15, 16, 17, 18,
and 19) which supply the localities as shown in Table 1 (WSC- Institute for Water
Technology).
• ">,:,;., (~,!~;' ~)5"U;·1~~I~·;t¥:·~<j~ &;(~~~\;~¥.ri~;R;~:.(~~iE ~i~"";i.i;;'; .:}~,~c"· ;j~~t;.~f~
MUNXAR 15 SANNAT 15 XLENDI 15
FONTANA 16 VICTORIA (UPPER) 16 XEWKIJA (LOWER) 16
GHARB 17 GHASRI 17 KERCEM 17
MARSALFORN 17 VICTORIA (LOWER) 17
SAN LAWRENZ 17 XEWKIJA (UPPER) 17
ZEBBUG 17 GHAJNSIELEM 18
MGARR 18 QALA 18
XAGHRA 18 NADUR 19
Table 1: Gozo Water Quality Zones. (Institute for Water Technology)
15
In 2005-06 the WSC produced just under 31 million cubic metres (culmt) of potable water in
Malta & Gozo. Approximately 13.4 million (43%) culmt. were produced from various
groundwater sources, the main one being Ta' Kandja Pumping Station which is a series of
underground galleries some 81an in length, 100m below ground. Groundwater production,
however, is not enough to meet demand which means that the Corporation has to convert
seawater into high-purity drinking water in its three RO plants at Pembroke, Cirkewwa and
Ghar Lapsi and blend it with groundwater. Moreover, the underground water table is affected
by illegal extraction, causing its salinity to rise to unacceptable levels, which has forced the
WSC to increase RO water production. This allows it to reduce groundwater production as a
percentage of overall water production. In 2005-06 approximately 17.4 million (57010) culmt.
of water was produced by RO plants.
This blend is stored in the 24 reservoirs in Malta, Gozo and Comino which have a total
capacity of 400,000 cubic metres. All the production, transfer and storage of water is
controlled and monitored in real time by remote sensing from the Control Room based at
Luqa. Reservoir levels, flow rates and pressures are kept at optimal operating parameters at all
times. The water distribution system is a vast and complex network: of over 2136 Ian of
pipes, pumps, reservoirs, automated and manual valves and other components. This network:
leads to approximately 142,000 water service connections to homes, businesses, industries,
hotels, schools, etc., serving over 400,000 persons throughout the Maltese Islands (WSC).
In the past the Maltese Islands had naturally present fluoride in the water supply, which never
exceeded the maximum of 1.4ppm. When reverse osmosis plants were introduced in Malta in
the early 199Os, the levels of fluoride in the polished water produced by the reverse osmosis
16
plants decreased to the negligible amount of less than 0.2 ppm. This led to Malta not being
exposed to sufficient fluoride to produce dental fluorosis.
In Gozo, water supplied to households in the past was all ground water pumped from bore
holes, with different areas in Gozo getting water from particular bore holes. This water
contains high levels of fluoride ranging from 1 ppm to 2.2 ppm. The Gozo system also used to
supply water to Rabat in Malta.
In 2004 a new system using a reverse osmosis polishing plant was introduced in Gozo. This
was done so that all the ground water in Gozo will be either polished or blended with polished
water. This is mainly done by using a Collection Scheme where ground water from all the
bore holes is pumped to one reservoir. A part of the ground water is introduced into one of the
three reverse osmosis plants and polished. This water is then blended with another two parts of
non- polished ground water and this mixture is then stored in the water quality zone reservoirs
and from there pumped to the households in Gozo. The polished water produced by reverse
osmosis plants contains less fluoride than the ground water and thus this new system produces
water which meets EU drinking water regulations parameters (personal conversation with Mr.
Anthony Rizzo, fonner CEO ofWSC).
In the Maltese Islands, water for public consumption is required to meet the standards set out
in European Legislation. The drinking water directive (98/83/EC) puts the limit for fluoride in
drinking water at 1.5 mg/l (1.5ppm). This directive was transposed into Maltese Law LN
23/2004 which came into force in January 2004. This was amended by LN 11612004 due to
the introduction of the Annexes. The parameter for fluoride had to be corrected to below
1.5mg/l in accordance with the relevant legal notice by 31 December 2005.
17
Fluoride analysis is perfonned by the Warer Services Corporation as part of their check and
audit monitoring in order to meet the requirements of LN 2312004 and 116/2004. Fluoride
levels are analysed at the village points twice a year for Maltese villages and on a monthly
basis in the case of Gozo villages. The results are read using UV MS spectrophotometry. The
WSC is undergoing a Drinking Warer Quality Project (funded by EU) which consists of the
refurbishing and upgrading the existing RO plants to improve the quality of drinking warer at
the consumers' tap. It is planned to increase the pumping from reverse osmosis plants and
decrease that from ground water to improve the quality of ground water. This would result in a
further reduction in the fluoride concentration in both Malta and Gozo (WSC- Institute of
Water Technology)
1.3 AIM AND OBJECTIVES
1.3.1 i\l1v.l
The aim of this study was to examine the levels of dental fluorosis in 5 year old and 12 year
old school children, so as to evaluate if dental fluorosis in Gozo is presently a public health
problem.
A path finder survey carried out in 1986 by Moller suggests that there was a public health
problem since values of >0.6 using Dean's index were recorded. These exceeded the
threshold value of 0.4-0.6. However, Moller himself questioned the results due to the
possibility that other enamel opacities were included as dental fluorosis.
18
1.3.2 OBJECTIVES
The objectives of this study were:
1 To determine prevalence of fluorosis in the deciduous dentition in Gozo, which has
never been determined previously.
2. To establish how large a public health problem dental fluorosis currently is in both
the deciduous (in 5 year olds) and the permanent dentition (in 12 year oIds) in Gozo.
3. To determine how aware the 12 year old Gozitan children are about the aesthetic . changes to their upper central incisors, associated with dental fluorosis.
4. To serve as a comparison for future studies which may be carried out to determine
the effect of polished water on fluorosis prevalence in the same population.
19
CHAPTER 2 LITERATURE REVIEW
INTRODUCTION
For more than a century, fluorides have been used to prevent dental caries. Although it is
scientifically proven that small concentrations of fluoride can significantly reduce dental caries
without any ill-effects, the usage of fluoride is still regarded as a controversial issue and is still
being researched.
2.1 FLUORIDES IN THE ENVIRONMENT
Fluorine is one of the most reactive elements and therefore, is rarely encountered in nature in
its elemental form. Combined chemically in the form of fluorides, the fluoride ion is the
thirteenth most abundant element, representing about 0.06 - 0.0<J01o of the Earth's crust.
Although there is an obvious abundance of Fluoride, it is negatively charged and thus
combines with positive ions to form stable compounds (e.g. calcium fluoride and sodium
fluoride) (MMWR Guidelines, 200 I) and is therefore not biologically available in its
elemental form.
2.1.1 THE CHEMISTRY OF FLUORIDE IN WATER
Fluoride occurs naturally in all water supplies. Artificial water fluoridation is the process of
adjusting the naturally occurring fluoride in water supplies to a level that is known to
benefit teeth.
20
Due to the presence of fluoride in the Earth's crust, water contains fluorides in varying
concentrations. Fluoride is present in water supplies as a result of having been dissolved out
of the rocks and soils over which the water has travelled. There are two normal forms of
fluoride, inorganic and organic; however, in dentistry, medicine and public health, only the
inorganic form (which yields the fluoride ion) is important. Inorganic fluoride also occurs
in two different forms: ionic fluoride, and nonionic fluoride. Importantly however, it is the
concentration of ionic fluoride in solution that is referred to (generally in parts per million -
ppm) when we talk of the fluoride concentration of a water supply. The concentration of
fluoride in water is analysed by the fluoride ion specific electrode which measures free
fluoride ions, not fluoride bound to metal ions such as calcium, magnesium, iron or
aluminium (Fejerskov et al 1996). The natural fluoride concentration of ground water is
affected by the availability and solubility of fluoride-containing minerals and the porosity
of rocks and soils over which the water passes, in addition to temperature, pH, and the
presence of other minerals such as calcium, aluminium and iron which may combine with
the fluoride ion. Ground waters in the United States have been reported to have fluoride
concentrations of up to 67 parts per million, and in parts of India and Africa much higher
concentrations have been reported (Fejerskov et alI996).
Waters with high fluoride content are usually found at the foot of high mountains and in areas
with geological deposits and ground waters. The natural concentration of the element in
ground water depends on such factors as the geological, physical and chemical characteristics
of the water supplying area, the consistency of the top soil, the porosity and permeability of
the aquifer rocks and the pH and temperature of the water. Owing to these factors, fluoride in
ground water fluctuates within wide limits - from <1 to >25 ppm. In surface fresh water,
21
which is less influenced by fluoride- containing rocks, the fluoride content is usually low -
0.01 to 0.3 ppm. Fluoride concentrations are higher in sea than in fresh water, averaging 1.3
ppm (Murray, 1986).
2.2 FLUORIDE VEIDCLES
Categorizing fluoride compounds into systemic and topical fluorides is not easily done; the
line between these categories gets blurred; some systemic vehicles have a topical effect and
some topical vehicles can inadvertently have systemic effects. The various vehicles available
can be categorized into three: population measures, individual measures and professionally
applied measures.
2.2.1 POPULATION MEASURES
A population measure is a group approach to the problem with little choice available to the
public. This includes:
- Water fluoridation, which is the addition of fluoride to the public water supplies;
- School-water fluoridation, which is the addition of fluoride to the school-water supply;
Determination of the most appropriate levels of fluoride in drinking water is crucial if the
measure is to be both effective and to receive public acceptance. This knowledge is important
both for communities intending to begin fluoridation, and for those with excessive natural
fluoride which require partial defluoridation.
22
Early studies of the relationship between fluoride concentration in drinking water, mottled
enamel, and dental caries were carried out by Dean. His aim was to find out the 'minimal
threshold' of fluoride - the level at which fluoride began to 'blemish the teeth'. He showed
conclusively that the severity of mottling was positively correlated with the fluoride
concentration in the drinking water (Dean, 1936). He presented evidence to show that if the
concentration of fluoride did not exceed 1 ppm there was no public health significance. The 21
city study showed that near maximal reduction in caries experience is seen with a
concentration of 1 ppm fluoride in the drinking water (Dean et aI., 1942 Figure 4). At this
concentration, fluoride caused only 'sporadic instances of the mildest forms of dental fluorosis
of no practical aesthetic significance'. Mottling of teeth began to be noticeable when the
fluoride concentration increa')ed above 1.5 ppm. Dean's original observations have been
substantiated by a number of investigators.
100 90 80 70
~60 Iso w
.~ 40 ;; v
30 20 10
Al 1 ppm maxim"", reduction in dental .jecay ! oo minrnal
fluorosis I I
OJ-.-,......,.--r-T""""'!"'"......,..~ ...
o 0 0'> 0'> 0" Ot' 0" ~~" y'" 'Vfo
12
10 Questionable
8 _Very Mild ~ _ Mild
6 2 ii: DModerab!
4 Severe --DMFT
2
o
Figure 4: 21 US cities study (Dean et aI1941-42): Fluorosis at age 12-14, according to natural water fluoride concentration (ppm).
23
The optimal range of community water fluoridation (optimal with respect to near maximal
dental caries prevention and minimal risk of enamel fluorosis) had previously been determined
to be 0.7 - 1.2 ppm, based on studies of fluid consumption according to the annual average of
the maximum daily air temperature. Failure to make adjustment for this factor may result in a
higher prevalence of fluorosis in warmer climates where more water is consumed. The
optimum caries-protective effect of different fluoride concentrations have been demonstrated
in hot climatic zones (0.6 ppm) and in cold zones (1.0-1.2 ppm). These standards are,
however, not appropriate for all parts of the world such as the tropical and sub-tropical areas.
Thus the level of 1.0 ppm has been viewed as an upper limit, even in a cold climate, and 0.5
ppm, now used in Hong Kong and recommended in the Gulf states, may be a more appropriate
lower limit (WHO, 1984).
The Forum on Fluoridation (Ireland 2002) has recommended that the optimal level of fluoride
in drinking water should be redefmed from the present level (0.8 to 1 ppm) to between 0.6 and
0.8 ppm, with a target value of 0.7 ppm after having taken into account the increase in the
major potential sources of fluoride intake.
2.2.2 INDIVIDUAL MEASURES
An individual measure offers the public a degree of choice. These measures however do not
necessitate utilization of health services. These are:
- Fluoridated toothpastes *
- Salt fluoridation
- Bottled water fluoridation
- Milk fluoridation
24
- Fluoride tablets and drops
- Fluoride mouthrinses
- Individually applied gels
*Fluoridated toothpaste contributes to the risk of enamel fluorosis since the swallowing reflex
of children aged less than six years is not always well controlled, particularly among children
aged less than three years (Nacacche et al 1992, Simard et al 1991). Children are also known
to swallow toothpaste deliberately when they like the taste. These reasons are why high
concentration fluoride toothpastes (1,500 ppm fluoride) are contraindicated for children less
than six years of age. Supported by more than half a century of research, the benefits of
fluoride toothpastes in preventing caries are firmly established (Marinho et al 2(03).
2.2.3 PROFESSIONALLY APPLIED MEASURES
Professionally applied measures also offer the public a degree of choice. However, they
require utilization of services. These include:
- Topical applications - fluoride gels, solutions and varnishes
- Prophylaxis paste
- Sequential rinses
- Slow release fluorides
25
2.3 FLUORIDE USAGE
Fluoride is being used widely on a global scale, for the most part with great benefits.
Fluoride toothpaste 450
Water fluoridation 210
Dropsffablets 20
Mouthrinses 20
Clinical topicals 20
Fluoridated salt 4.0
School fluoridation 0.2
Table 2: Tentative estimates of number of people throughout the world using various types of fluoride therapy and preventive measures (Murray et oZ., 1991).
2.4 FLUORIDE AS A CARIES PREVENTIVE AGENT
Dental caries is an infectious, multifactorial disease affecting most persons in industrialised
countries and some developing countries (Bratthal et aI, 1996).
The first suggestion of a possible connection between the fluoride ion and the prevalence of
dental caries occurred towards the end of the nineteenth century, when Sir James Crichton-
Browne, (1892) stated " ... .1 think it well worthy of consideration whether the reintroduction
26
into our diet of child bearing women and children, of a supply of fluorine in some suitable
natural form .... might not do something to fortify the teeth of the next generation."
Dr. Frederick McKay would appear not to have taken account of Crichton-Browne's words
when he spent almost 30 years searching for the cause of the "Colorado stain" in Colorado
Springs and the surrounding EI Paso county, or "denti di chiaie" in Naples, Italy, before
realizing, in 1931, that the occurrence of mottling, which was localized in definite geographic
areas concomitant with a reduced rate of caries, was due to a high fluoride content in the water
supplies.
"We have discovered the presence of hitherto unsuspected constituents in this water. The high
fluorine content was so unexpected that a new sample was taken with extreme precautions and
again the test showed fluorine in the water" (Churchill, 1931).
Fluoride reduces the incidence of dental caries and slows or reverses the progression of
existing lesions. Although pit and fissure sealants, meticulous oral hygiene and appropriate
dietary practices contribute to caries prevention and control, the most effective and widely
used approaches have included fluoride use. The widespread use of fluorine has been a major
factor in the decline in the prevalence and severity of dental caries in economically developed
countries (Bratthal et ai, 1996). Although this decline is a major public health achievement, the
burden of disease is still considerable in all age groups (MMWR 200 1).
Since many fluoride modalities are effective, inexpensive, readily available and can be used
both in public and private health care settings, their use is likely to continue. Research about
fluorides led to the development of various modes of fluoride use. Different regimes, vehicles
and materials involving fluoride were tested and later applied to increasing groups of
27
populations throughout the world, starting from the fluoridation of the piped water supplies in
Grand Rapids, Newburgh and Brantford.
There has been a decline in dental caries prevalence and incidence during the last two decades,
both in the economically developed and in economically developing countries. This decrease
is considered to be largely due to the widespread use of fluoride. (Buzalaf et al 200 1). In a
systematic review of 214 studies on water fluoridation, an increase in the proportion of caries
free children and a reduction in the number of teeth affected by caries were observed (Mc
Donagh et al 2000).
To develop and apply appropriate and effective caries prevention and control strategies,
identification and assessment of groups and persons at high risk of developing new carious
lesions is essential (Meskin 1995). Caries risk assessment is difficult because it attempts to
account for the complex interaction of multiple factors.
Populations believed to be at increased risk for dental caries are those with low socioeconomic
status or low levels of parental education, those who do not seek regular dental care and those
without access to dental services. Persons can be at high risk for dental caries even if they do
not have any of these recognised factors.
Individual factors that possibly increase risk include active dental caries; a history of high
caries rate in older siblings or care givers; root surfaces exposed by gingival recession; high
levels of infection with cariogenic bacteria; impaired ability to maintain oral hygiene;
malformed enamel or dentine; reduced salivary flow because of medications, radiation
treatment or disease; low salivary buffering capacity and the wearing of space maintainers,
orthodontic appliances or dental prostheses. Risk can increase if any of these factors are
combined with dietary practices conductive to dental caries (e.g. frequent consumption of
28
refined carbohydrates). Risk decreases with adequate exposure to fluoride (Meskin 1995, Pitts
1998).
Children and adults who are at low risk for dental caries can maintain the status through
frequent exposure to small amounts of fluoride such as fluoridated drinking water and using
fluoride dentifrice. Children and adults at high risk of dental caries might benefit from
additional exposure to fluoride such as fluoride supplements and professionally applied
products.
2.5 EFFECT OF FLUORIDE - MECHANISM OF AcrION
An understanding of the mechanism of action of fluoride is clearly important to ensure its
appropriate use as a caries preventive agent (Clarkson, 1991). The exact mechanism of action
through which fluoride impacts on caries is not fully understood although a consensus has
emerged in recent years. Fluoride can impart a cariostatic effect by different mechanisms,
depending on the amount of fluoride present at the enamel-plaque interface (Margolis and
Moreno, 1990).
The two main hypotheses which have been proposed to account for the anti-caries effect of
fluoride are through a pre- and post- eruptive effect. These can be divided into a number of
mechanisms.
29
2.5.1 PRE-ERUYfIVE EFFECT
* by promoting the growth of larger and more perfect crystals;
Fluoride is incorporated into enamel during tooth formation producing a more perfect crystal,
with a lower carbonate content, which is consequently more resistant to acid action; crystals
tend to dissolve in areas of imperfection. The pre-emptive benefits may be especially
important for reducing pit-and-fissure lesions (Groenveld et aI., 1990).
2.5.2 POST-ERUPTIVE EFFECT
* CrystaHization;
By reducing the rate of dissolution of enamel in acids through incorporation of fluoride ions
into the apatite lattice - fluoride and hydroxyl ions have the same charge, and they can
interchange converting hydroxyapatite into fluoridated hydroxyapatite. The latter mineral is
both more stable and acid resistant than pure hydroxyapatite. This mechanism could also act
pre-eruptively (Burt & Eklund, 1992). However, it is important to note that relatively high
concentrations of fluoride within the enamel are required for a significant reduction in enamel
solubility to result. The evidence is contradictory on whether the concentration of fluoride in
sound enamel is sufficient to reduce its solubility (Murray et aI., 1991). Levine (1976) argues
that a high concentration of enamel fluoride could not by itself explain the extensive
reductions in caries that fluoride produced.
*inhibition of the e1l1.3me system of acid producing bacteria;
Fluoride in plaque inhibits glycolysis, the process by which sugar is metabolized by bacteria to
produce acid. The main site of fluoride inhibition is in the Emden-Myerhof pathway of acid
30
production, by its action on enolase, the enzyme that converts phosphoglyceric acid to
phosphoenolpyruvic acid. When this reaction is blocked, phosphoglycerate accumulates and
later products, such as phosphoenolpyruvate (PEP) and lactic acid, are not fonned. This has
several consequences when it occurs in plaque:
1. The reduced production of1actate obviously impairs the ability of the bacterial plaque
to cause caries (Murray et al., 1991).
2. In many bacteria, the uptake of glucose requires the presence of PEP, so uptake is
reduced by fluoride (Hamilton, 1977).
3. The reduced glucose uptake prevents the synthesis of glycogen; the intracellular
polysaccharide that acts as a store of carbohydrate and makes it possible for oral
bacteria to continue to produce acid after the dietary sugar has been washed away by
saliva (Murray et al., 1991).
4. Fluoride reduces the pH within the bacteria (by dissociation ofHF) - this increases the
W concentration in the cell and this may reach a level so far removed from the
optimum pH of the enzymes that acid production is reduced or may even cease
(Eisenberg and Marquis, 1980).
Many bacteria are more sensitive to fluoride at low pH levels. It has been suggested that
fluoride reduces their acidurity. The latter depends on the bacteria's power to extrude It" from
the cytoplasm, a process that requires ATPase enzyme. This enzyme is very sensitive to
fluoride in S. mutans. Marquis, (1990) suggested that fluoride in plaque may inhibit this
ATPase leading to a build up of acid which in tum inhibits enolase and other enzymes. In
many cases, enzymes have metal ion co-factors (example Fe2+ or Fe*) and the fluoride ion
31
binds to these ions and stops the co-factors from working. However the enzymes that do not
have metal co-factors are still inhibited. Thus, there must be another mechanism of action.
There is also evidence that plaque fluoride can inhibit the production of extracellular
polysaccharide by cariogenic bacteria, a necessary process for plaque adherence to smooth
enamel surfaces (Hamilton, 1990). There is, however, a lot of contradiction regarding this
process (Murray et al., 1991).
* By changing the balance between dissolution and precipitation in caries lesions towards
precipitation.
Fluoride can act as a catalyst in the precipitation of hydroxyapatite. The ionic fluoride in the
aqueous fluid of the plaque and among the crystals within the enamel or dentine encourages
the repair of the early carious lesion by reprecipitation of the enamel crystals shifting the
demineralizationlremineralization equilibrium towards mineralization. The reSUlting inhibition
of demineralization and/or the enhancement of remineralization can explain the effects of
application of low fluoride concentrations such as from fluoridated drinking water and the use
of fluoride containing dentifrices and mouth rinses (Koulourides, 1990).
In addition to the mechanisms described, high-concentration fluoride gels may have a specific
bactericidal action on cariogenic bacteria in the plaque (Bowden, 1990; Loesche, 1977).
Fluoride action may best be described as reducing lesion progression rather than actually
preventing the initiation of the disease (Clarkson, 1991). The weight of evidence favours the
view that fluoride's most important caries-inhibitory action is post-eruptive, though the
respective roles of pre-emptive and post-eruptive fluoride continue to be debated (Horowitz,
1990; Thylstrup, 1990).
32
Current scientific evidence therefore indicates that fluoride works through several
mechanisms. The current opinion is that the solubility - remineralization concept, with its
emphasis on a constant flow of ionic fluoride, is the major effect (Fejerskov et al., 1981).
Because of the various possible mechanisms through which fluoride can have an impact, the
method of delivery is going to be important This in tum will influence the vehicle. The
optimum characteristics for fluoride is a low concentration for as long as possible, a frequent
low dose. This is important to maintain a significant concentration in saliva and plaque fluid
for the control of enamel dissolution. This is important in making the appropriate scientific
choice.
Fluoride exerts its effect primarily through topical action. There is some uncertainty whether
salivary or plaque fluoride is primarily responsible, but the fact remains that the effect is
topical. Although systemic fluoride may be available via the saliva, only local fluoride is
necessary for the success of the process (Leverett, 1992).
2.6 FLUORIDE AND THE BODY
Fluoride is considered to be a 'beneficial element for humans' because of its positive impact on
dental health (National Research Council, 1989), it was once considered to be an essential
nutrient for human growth (National Research Council, 1974). However, available evidence
did not justify classifying fluoride as an essential element by accepted standards (National
Research Council, 1989).
33
2.6.1 FLUORIDE INTAKE BY MAN
Because of the environmental presence of fluoride, individuals are exposed to various levels of
intake through foods, water, industrial and phannaceutical products, and other sources.
Waterborne fluoride has been said to represent the largest single source of daily intake of this
ion. The daily amount of fluoride intake through water varies with climate and age of the
individual (Murray, 1986). In some parts of the world, however, staple diets, are particularly
high in fluoride, and this source can be the main contributor. On the basis of extensive analysis
reported by several authors, the total daily fluoride intake by man may vary from 0.2 mg of
fluoride per day in infants to 5.0 mg of fluoride per day in adults. Although there is no
consensus as to the maximum safe daily dosage of fluoride, a total intake of between 0.05 and
0.07 mg FlKg body weight has been suggested (Murray, 1986).
2.6.2 ABSORPTION, RETENTION AND EXCRETION
Ingested fluoride is absorbed mainly from the upper gastrointestinal tract. The process occurs
by passive diffusion. The half-time for absorption is approximately 30 minutes, so peak
plasma concentrations usually occur within 30 to 60 minutes; the time for its occurrence is
independent of the amount of fluoride ingested Absorption across the oral mucosa is limited
and probably accounts for less than 1 % of the daily intake. Absorption from the stomach
occurs readily and is inversely related to the pH of the gastric contents (Whitford, 1990). High
concentrations of dietary calcium and other cations that form insoluble complexes with
fluoride can reduce fluoride absorption from the gastrointestinal tract (Whitford, 1986).
Blood plasma is considered to be the central compartment into which and from which fluoride
must pass for its subsequent distribution and elimination. The scientific literature contains
34
rather a wide range, 0.7 - 2.4 IlmoJ/L, for the 'normal' plasma fluoride levels (Myers, 1978;
Guy, 1979). Such wide differences might be due to unrecognized population differences in
fluoride intake, in fluoride metabolism, or the result of problems associated with fluoride
analysis.
Plasma fluoride concentrations rise and fall according to the pattern of fluoride intake. This is
dependant upon the fluoride vehicle used. The rates of absorption, soft tissue distribution,
calcified tissue uptake and renal excretion of fluoride all influence the plasma fluoride
concentration at any given time after fluoride intake. The height of the plasma peak is
proportional to the fluoride dose ingested and the rate of absorption, but is also determined by
the body weight of the subject. The plasma half-life for fluoride in human adults ranges from 4
to 10 hours. A steady state relationship exists between plasma and soft tissue fluoride levels
(Whitford, 1990).
Absorbed fluoride begins to leave the blood within minutes, concentrating in bones and the
kidneys. Of the fluoride absorbed by the young or middle-aged adult each day, approximately
50% will be associated with calcified tissues within 24 hours and the remainder will be
excreted in urine.
2.6.3 FLUORIDE IN TEETH AND BONE
Fluoride has an affinity for the calcified tissues, that is, bone and developing teeth. Fluoride
that is not excreted is deposited in these hard tissues, though storage is dynamic rather than
inert. Bone fluoride levels range from 800 to 10,000 ppm, depending on many factors,
including age and fluoride intake (Wiedmann and Weatherall, 1970; Whitford, 1990). Fluoride
is not irreversibly bound to bone. Fluoride levels in the outer layers of dental enamel range
35
from 400 to 3,000 ppm and decrease rapidly with greater enamel depth. Fluoride
concentrations in soft tissue rise or fall parallel to serum fluoride levels, but because the
excretion and deposition mechanisms operate so rapidly there is negligible retention of
fluoride in the fluids of soft tissues other than the kidney (Whitford, 1986).
2.6.4 EXCRETION
The principal route of excretion of absorbed fluoride is by the kidneys via the urine. Excretion
of fluoride in urine begins very rapidly after uptake. Approximately 50010 of the fluoride
absorbed from the gastrointestinal tract of adults each day is excreted in the urine. Some
excretion takes place through sweat and fluoride can also appear in saliva. About 10-25% of
fluoride is not absorbed and is excreted in the faeces. Fluoride crosses the placenta, but it does
not seem to be excreted in milk to any significant extent.
Factors which alter urinary pH may profoundly affect the quantitative features of the
metabolism of the ion (Whitford, 1990). Such factors include the composition of the diet,
certain metabolic diseases such as diabetes mellitus, certain drugs, and the altitude at which
the individual resides.
The importance of renal clearance in the body's regulatory mechanism means that when
kidneys are not functioning properly, the amount of fluoride stored in the body can increase.
Special consideration, with regard to fluoride ingestion, should thus be given to people with
chronic kidney failure. There is, however, insufficient evidence to recommend that all patients
with renal disease drink fluoride free water (Burt and Eklund, 1992).
36
2.7 FLUORIDE TOXICITY
Like all other necessary elements fluoride can be toxic at high doses. Table 3 shows the
degrees of potentially toxic ingestion of fluoride.
Acute fatal poisoning, 10 Kg child
Acute fatal poisoning, 3-year old child
Acute fatal poisoning, adult renal dialysis
Short-term nonserious nausea in elementary school children
Severe skeletal fluorosis
Dental fluorosis
Acute fatal poisoning in animals
2.5 - 5.0 g, 2 - 4 hours
320 mg, 2 - 4 hours
--435 mg, ~3 hours
Dialysate fluid 30 - 50 ppm F, for 3 hours
93 - 375 ppm F in drinking water, small amounts
10 - 25 mg F daily, 10 - 20 years
<0.1 mg F /Kg body weight/day during tooth development
~50 mg F/Kg body weight
Table 3: Degrees of potentially toxic ingestion of fluoride (Burt & Eklund, 1992).
2.7.1 ACUTE TOXICITY
A review of the literature reveals a wide range of estimates for the actual lethal dose in
humans. They range from 6-9 mg FlKg (Driesbach, 1980) to over 100 mg FlKg (Lidbeck et
aI., 1943). The 'certainly lethal dose' (CLD) corresponds to a fluoride dose range of from 32 to
64 mg FlKg. While this is important information, it is of limited utility. Of more value is the
37
'probably toxic dose' (PTD), which has been defined as "the minimum dose that could cause
toxic signs and symptoms, including death, and that should trigger immediate therapeutic
intervention and hospitalization" (Whitford, 1987). It is concluded, from various reports, that
the PTD is approximately 5 mg FlKg (Dukes, 1980; Eichler et aI., 1982; Horowitz, 1978).
The symptoms associated with acute toxicity include salivation, nausea, vomiting, diarrhoea,
fatigue and cramps. In cases of fatal poisoning, death occurs within 24 hours as a result of
respiratory or cardiac failure.
2.7.2 CHRONIC TOXICITY
The long term ingestion of amounts of fluoride above adequate therapeutic levels will result in
fluorosis.
2.8 FLUOROSIS
2.8.1 DENTAL FLUOROSIS
Dental fluorosis is defined as a permanent hypomineralization of enamel, characterized by
greater surface and subsurface porosity than in normal enamel, resulting from excess fluoride
reaching the developing tooth during developmental stages (Fejerskov et aI., 1990).
Several different factors may result in changes in the normal appearance of the enamel (Small
and Murray 1978, Pindborg 1982). The single most studied causal factor is fluoride which can
result in a range of clinical manifestations referred to collectively as dental fluorosis. This
condition can be distinguished from other defects of the enamel based on enamel colour,
38
distribution of the condition on the affected tooth or within the mouth, and the extent to which
the enamel is left intact (Rozier 1994).
Enamel changes in populations exposed to differing levels of fluoride were first described by
McKay in his initial publication with black (McKay and Black, 1916). A precise description
was provided by McKay (1929) in a subsequent paper, in which he stated, " there are all
gradations, from the merest flecking of certain teeth, with white spots scattered about
otherwise normal enamel, to other conditions in which the entire enamel structure is uniformly
dead paper white, with or without the presence of the brown discoloration; and still others in
which there has been the most pronounced gross destruction of the enamel surfaces by what
may be called, for want of a better tenn, corrosion."
Severe forms of dental fluorosis can occur only when young children ingest excess fluoride,
from any source, during critical periods of tooth development. Tables 4 and 5 show the
chronology of tooth development in the deciduous dentition and pennanent dentition
respectively. The occurrence of enamel fluorosis is reported to be most strongly associated
with cumulative fluoride intake during enamel development, but the severity of the condition
depends on the dose, duration, and timing of fluoride intake (Larsen et aI., 1987). The
mechanism underlying the development of dental fluorosis has not been conclusively
determined. In the past it was believed that the excessive fluoride intake interfered with the
function of ameloblasts, perhaps inhibiting the secretion of, or altering the composition of the
enamel matrix proteins. This now appears unlikely for several reasons including the fact that
the risk of dental fluorosis is lowest during the secretory stage of enamel development
(Fejerskov et all996).
39
3rd-5th month in utero
Age 4-5 months
Age 6-8 months
5th month in utero
Age 9 months
Age 16 -20 months
5th month in 6th-7th month in utero utero
Age 6 months Age 10-12 months
Age 12-16 Age 21-30 months months
Table 4: Primary teeth (deciduous dentition) chronology.
u L u L u L u L
3--4m 3--4m 10-12m 3-4 m 4-5m 4-5m Birth Birth
4-5y 4-5y 4-5y 4-5y 6-7y 6-7y 2.5-3y 2.5-3y
7-8y 6-7y 8-9 Y 7-8y 11-12 Y 9-10 Y 6-7y 6-7y
Table 5: Permanent teeth chronology
Microscopically, the structural arrangement of the crystals appears normal, but the width of
the intercrystalline spaces is increased, causing pores. The degree and extent of porosity
depends on the concentration of fluoride in the tissue fluids during tooth development
40
(Fejerskovet alI990). In fact, the risk of dental fluorosis, based on animal studies, is directly
related to the interaction of the circulating fluoride concentrations and the time, that is, the area
under the time-concentration curve. Thus it appears that dental fluorosis can result from a
range of plasma fluoride concentrations provided that they are maintained for sufficiently long
periods (Whitford 1997). With increasing severity of fluorosis, the fluoride concentration
throughout the enamel, the depth of enamel involvement, and the degree of porosity also
increases (Fejerskov 1990).
Fluorosis is less prevalent and less apparent in primary teeth than in pennanent teeth, and, in
any case, fluorosis of the primary teeth has only short- tenn rather than long-tenn
consequences (BuzaIaf 200 1). Therefore the major concern about fluorosis is in the permanent
dentition, particularly with maxillary incisors.
Evidence suggests that 0.03 to 0.1 mg FlKg body weight as the borderline zone at least for
European children (Fejerskov et aI., 1987). Studies in Kenya have found fluorosis with
average intakes as low as 0.03 mg FlKg body weight (Baelum et al., 1987). Further research is
thus needed in this area. Research evidence also suggests that periodic 'spikes' of high F in
plasma are more likely to produce fluorosis than a consistent day-to-day intake (Burt and
Eklund,1992).
The post- secretory and early maturation stages of enamel development appear to be most
susceptible to the effects of fluoride (DenBesten PK, Thariani H.1992); these stages occur at
varying times for different tooth types. For central incisors of the upper jaw, for example, the
most sensitive period is estimated at age 15-24 months for boys and age 21-30 months for
girls (DenBesten PK, Thariani H.I992, Evans RW, Stamm JW 1991).
41
Other factors that may increase the susceptibility of individuals to dental fluorosis are altitude
(Angrnar Mansson, Whitford 1990, Maybelya 1992, Whitford 1997 , Yoder 1998), renal
insufficiency (Juncos 1972, Kaminsky 1990, Porcar 1998, Turner 1996) and malnutrition
(Rugg-Gunn et al 1997 , Yoder 1998). Some of these factors, however, can produce enamel
changes that resemble dental fluorosis in the absence of significant exposure to fluoride.
Studies of dental fluorosis, done in areas with 8.I,d witt'iout fluoridated dr.r.king water, have
identified four major risk factors: use of fluoridated drinking water, fluoride supplements,
fluoride dentifrice and infant formulas before the age of seven years. Some manufactured
children foods and drinks may also be important contributors to total daily fluoride intake
(Buzalaf et aI2001).
Concerns regarding the risk for enamel fluorosis are limited to children aged <6 years with the
most critical period for developing fluorosis on the permanent central incisors estimated to be
between 22 to 25 months of age (Evans and Darvell 1995). The enamel is no longer
susceptible once its pre-emptive maturation is complete. Children aged >6 years are
considered past the age that fluoride ingestion can cause cosmetically objectionable fluorosis
because only certain posterior teeth are still at a susceptible stage of enamel development, and
these will not be readily visible.
In addition, the swallowing reflex has developed sufficiently by age 6 years for most children
to be able to control inadvertent swallowing of fluoride toothpaste and mouthrlnse.
The very mild and mild forms of enamel fluorosis (Figure 5) appear as chalklike, lacy
markings across a tooth's enamel surface that are not readily apparent to the affected person or
casual observer. In the moderate form, >50% of the enamel surface is opaque white (Figure 6).
42
Figure 5: Mild Fluorosis (by Elke Babiuk adapted from http://fluorideaiert.org/dentaifluorosis.htm )
Figure 6: Mild to Moderate Fluorosis (by Elke Babiuk adapted from http://fluorideaiert.orgidentai-fluorosis.htm )
The rare, severe form of dental fluorosis manifests as pitted and brittle enamel (Figure 7 and
Figure 8). After eruption, teeth with moderate or severe fluorosis might develop areas of
brown stain. In the severe form, the compromised enamel might break away, resulting in
excessive wear of the teeth.
43
Figure 7: Moderate to Severe Fluorosis (by David Kennedy adapted from http://fluoridealeI1.orgldental-fluorosis.htm )
Even in its severe form, enamel fluorosis is considered a cosmetic effect, not an adverse
functional effect (Kaminsky et al1990, Clark et aI1993). Some persons choose to modify this
condition with elective cosmetic treatment.
Figure 8: Severe Fluorosis (by Hardy Limeback adapted from http://fluoridealert.orgldental-fluorosis.htm )
44
The benefits of reduced dental caries and the risk for enamel fluorosis are linked. Early studies
that examined the cause of "mottled enamel" (now called moderate to severe enamel fluorosis)
led to the unexpected discovery that fluoride in community drinking water inhibits dental
caries (Dean 1938). Historically, a low prevalence of the milder forms of enamel fluorosis has
been accepted as a reasonable and minor consequence balanced against the substantial
protection from dental caries from drinking water containing an optimal concentration of
fluoride, either naturally occurring or through adjustment (Dean 1942).
2.S.1.1 INDICES OF DENTAL FLUOROSIS
Several indices have been used to describe the clinical appearance of dental fluorosis. The four
major ones used are:
• Dean's index (developed between 1934 and 1942)
• Thylstrup and Fejerskov Index ( 1978)
• Tooth Surfuce Index of Fluorosis (Horowitz et at 1984)
• Fluorosis Risk Index (pendrys 1990)
Other indices which have sometimes been used are Smith's Index, Developmental Defects of
Enamel (ODE) and Clarkson and O'Mullane Index. These indices are not very popular since
they are more examiner subjective than the above mentioned indices.
The continued use of Dean's index for more than fifty years is a testament to its simplicity
and utility. It classifies individuals into 5 categories, depending on the degree of enamel
45
alteration, and which was based on the identification of the 2 most severely affected teeth,
giving ordinal numbers as the severity of the enamel alteration increased.
The index has been criticised because it presupposes the condition and because criteria are
unclear for some categories or lack sensitivity, particularly for severe fluorosis. Another
criticism is related to its use of either the person or the community as the unit of measurement.
While basing the person- level score on the most severely affected teeth serves the purpose of
measuring the maximum dental effects of fluoride dental exposure, important in determining
the safe level of exposure to fluoride from drinking water, it is not useful in those instances
where the type of tooth or surface affected is important. Three problems can arise from use of
this person score:
• Aggregation across surfaces or teeth may prevent adequate discrimination among
individuals, particularly at high fluoride levels where all subjects may have pitting
in some teeth.
• A person- level score may misclassify an individual if aesthetic considerations are
more important than biological ones, since the most affected teeth tend to be the
posterior ones which have less cosmetic importance than anterior teeth.
• The person-score does not permit determinations of possible changes in the level
of fluoride exposure during tooth development.
Since the Community Fluorosis Index (CFJ) is an average, it provides little information about
the variation within a popUlation, particularly if measures of variance are not provided, which
is the usual case when reporting CFI values. Also, since it is a weighted average, individual
scores may not correlate well with the community score and thus may misrepresent the dose
response relationship between fluoride and fluorosis since a large number of questionable
46
ratings can produce a CFI of the same magnitude as that in a population with fewer
questionables but with higher scores (Fejerskov et aI1988).
Another major criticism of Dean's Index concerns statistical manipulation and reporting,
primarily related to the use of the CFI. Since the classification system is based on an ordinal
scale, and the distribution of scores is usually not normal at some levels of fluoride exposure,
the mean is an inappropriate statistic. Further to this the weights assigned to each category are
arbitrary.
The Thylstrup and Fejerskov (TF) Index is appealing to clinicians and epidemiologists
since it corresponds closely to the histological changes that occur in dental fluorosis and to
enamel fluoride concentrations, thus having biological validity. A 10 point ordinal scale is
used to classify enamel changes associated with increasing fluoride exposure (ranging from 0
to 9 with a score of 0 being no fluorosis and a score of 9 being the worst type of dental
fluorosis). Most investigations have only used facial surfaces of teeth and this has become the
recommended procedure since 1988. This recommendation is based on the similarity of the
different surface scores on the same tooth, and on the difficulty of getting an accurate
assessment of fluorosis on occlusal surfaces because of the likelihood of scores being affected
by occlusal wear (Rozier 1994). The clinical and histological bases for the criteria used for
scoring fluorosis with this index have clarified by the way in which fluorosis is distributed
over the tooth surface in the case of continuous exposure to constant levels of fluoride during
tooth development, as well as the role of enamel loss in fluorosis. The approach used on
formulating scoring criteria has had the effect of reducing some of the subjectivity in scoring.
47
The Tooth Surface Index of Fluorosis (TSIF) makes a useful contribution because it
provides clear diagnostic criteria and provides for an analysis based on aesthetic concerns. It
classifies individuals into 8 categories. In this index a value is given for each anterior tooth
surface not restored (buccal and lingual) and three values for posterior tooth surfaces (buccal,
lingual and occlusal). An advantage of TSIF is that it contains no questionable category, like
TFI, and thus a positive score is assigned to the first signs of fluorosis. TSIF scores 1-3 are
based on the area of the tooth surface affected, derived by visually coalescing all areas of
fluorosis and relating that area to the total visible enamel of a particular surface. The area of a
surface affected can provide a useful indication of severity when exposure to fluoride is
continuous during the development of the tooth. With interrupted fluoride exposure, however,
only a portion of the surface may be affected, and to various degrees depending on the level of
exposure. An inaccurate assessment of severity can be provided in those instances where
continuous and interrupted exposures result in identical scores based on surface area affected,
yet the severity of fluorosis differs.
Another point concerns the score of "4", given when staining is present in conjunction with
any of the three conditions indicative oflower scores. If one's primary interest is measuring the
aesthetic consequences of fluorosis, the index is probably an ordinal one. However, if the
index is being used solely as an indicator of the biological effects resulting from fluoride
exposure, the TSIF must be considered a nominal scale rather than an ordinal one according to
the purest defmition of scales. Since staining of any portion of the surface is given precedence
over the proportion of the surface affected with fluorosis, a score of "4" may be given when an
area equivalent to a TSIF score of "1" is present However, stain rarely occurs before a "mild"
level of fluorosis is reached according to Dean's Index, most likely corresponding to a score of
48
"3" in the TSIF, and should not be of major concern if one wishes to treat the index scale as
ordinal.
The aesthetic orientation of this index is evident once again in the higher degrees of fluorosis,
where staining occurring in conjunction with discrete pitting is given a separate score. Finally,
a distinction between discrete pitting and more advanced confluent pitting is made, making the
index more sensitive than Dean's to higher degrees of fluorosis. Results obtained with the use
of this index are presented as various frequency distributions of surface scores or of the
maximum mouth score, either for all surfaces or for specific surfaces such as facial surfaces of
anterior teeth or occlusal surfaces of first molars.
With use of the TSIF, examiner reliability may be of more concern than with Dean's Index or
the modified TFI because of the larger number of assessments to be made (72 surfaces vs. the
usual maximum of 28 teeth or buccal surfaces in children). The added lingual surfaces are
more difficult to visualize than buccal surfaces, which also adds to the concern about examiner
reliability. The original publication documented examiner reliability for the two examiners
originally involved in the index. Intraexaminer agreement ranged from 0.66 to 0.83 for the two
examiners and for all teeth combined and for anterior teeth only. Interexaminer agreement as
measured by the kappa was 0.35 for all teeth, and 0.54 for anterior teeth, indicating some
difficulty in achieving an acceptable level of agreement for all teeth.
The TSIF has two major advantages over Dean's Index. First, criteria for scoring in the TSIF
are clearer, and consequently, subjectivity should be reduced in their application. The other
advantage derives from the scoring of surfaces rather than individual teeth. Surface scores
allow for analyses of fluorosis on the labial surfaces of maxillary anterior teeth (those surfaces
49
of greatest aesthetic concern), and a more precise correlation of age of exposure with tooth
development, useful in analytical studies on risk factors and biological effects.
A further advantage may be the added sensitivity gained through the increased number of
scores compared with other indices. This sensitivity depends, of course, on the differences that
exist among the different surfaces, particularly between facial and lingual surfaces.
Further work needs to be done to determine the advantages of including all surfaces in an
examination. The added precision gained from such an exam must be weighed against a
possible small surface-to-surface variation for a given tooth, the higher probability of loss of
data on occlusal surfaces because of restorations, and the possibility of reduced examiner
consistency because of the inclusion of hard-to-see lingual surfaces.
The Fluorosis Risk Index appears to be particularly useful for analytical epidemiological
studies since it is designed to permit a more accurate identification of associations between
age- specific exposures to fluoride and the development of dental fluorosis (pendrys
1990).The validity of the fluorosis risk index utility has still to be determined since it has not
yet been widely used.
The unique feature of the FRI is that each tooth is divided into zones that correspond to the age
at which they begin development, and can be related to narrow age-bands of fluoride
exposure, such as a 12-month time period. Enamel surface zones that begin fonnation during
the first year of life (i.e., between birth and the :first birthday) and those that begin formation
between the third and sixth years of life (i.e., between the second and sixth birthdays) are
identified and scored separately. The buccal surface and the incisal edge/occlusal table of each
permanent tooth (excluding third molars) have been divided into four scoring zones: (I) the
50
incisal edge/occlusal table, defined as the enamel surface within one millimetre of the incisal
edge of the tooth; (2) the incisaVocclusal third of the buccal surface; (3) the middle third of the
buccal surface; and (4) the cervical third of the buccal surface.
The portions of the enamel that begin fonnation during the first year of life are referred to as
Classification I enamel surface zones. The Classification II are enamel surface zones that
begin fonnation during the third through sixth years of life. The other category are the
unassigned enamel surface zones for which categorization is questionable, based on the
available literature on tooth development, or where their development occurred after 5 years of
age. Roughly 112 zones are scored, with 10 belonging to Classification I, 48 to Classification
II, and the remaining 54 to unassigned zones.
Each zone is scored as either negative for fluorosis, questionable for fluorosis, positive for
mild-to-moderate fluorosis, or positive for severe fluorosis. A surface zone is diagnosed as
being positive when 50010 or more of the area of a zone being scored is affected-according to
the authors, a severity level equivalent to the "mild" category in Dean's Index. The criterion for
this categorization in Dean's Index, however, is based on the proportion of the entire tooth that
is affected, not a surface or portion of a surface. Thus, the two classifications may not be
equivalent
Subjects are identified as cases or controls for each of the two surface zones based on the
distribution of scores within each. At least two surfaces of a particular zone must have scores
of 2 or 3 in order to be considered a case. In the analysis, risk factors are considered separately
for each classification.
The single use of this index has been reported by the authors (pendrys and Katz, 1989).
Examiner reliability studies during its initial use produced excellent results. The two
51
examiners achieved interexarniner agreement, as measured by the kappa statistic, of 0.76 and
0.82 for Classification I and Classification II surface zones, respectively. Kappa statistics for
intra-examiner agreement varied from 0.83 to 1.00 for the two types of surface classifications.
The strengths and weaknesses of the FRI should become more apparent with its use by other
investigators. The biological and analytical premises appear sound. While the ability exists to
collapse FRI values to yield prevalence data, the index was not designed for this purpose. In
most situations, the other three indices are better suited to provide strictly prevalence data. The
index is complex, both from a biological perspective and in its application. Acceptable levels
of examiner reliability may be difficult to establish due to this complexity. Further, results
cannot be compared with those of any of the established indices used in determining
prevalence. Therefore, the index cannot serve the dual purpose of providing prevalence
estimates as well as estimates of risk.
A primary premise of this index is that scores for the two age-related developmental zones are
independent The differential diagnosis of fluorosis required of this and other fluorosis indices
is usually based on an initial overall assessment of the dentition, since the intra-oral
distribution of fluorosis is useful in making a diagnosis. Before proceeding with specific tooth
calls, the examiner usually makes the initial assessment as to whether the subject is a case or
not This procedure cannot be followed with the FRI because of the likelihood of bias in
making determinations for the Classification I and II zones. Any existing bias in the
determinations between case, control or questionable in Classifications I and II could weaken
or even mask associations between exposure and outcomes. Case definition will affect the
identification of risk factors. The FRI is conservative in the definition of surface zones and in
the severity level chosen for a case. This conservative approach may create difficulties in
52
identifying those factors that carry a small risk, or are widespread in the study population.
There is also a concern about the validity of assessments in Classification I, which are based
on only 10 surfaces, the incisal edges of mandibular incisors, maxillary incisors, and occlusal
surfaces of first molars. Incisal edges of anterior teeth are more likely to demonstrate clinical
signs of fluorosis than many other surfaces, probably because of a smaller amount of dentin,
their increased translucency, and the tendency for these surfaces to be drier than others.
Further, the occlusal surfaces of first molars are those surfaces most likely to be excluded
because of restorations, and presumably dental sealants. Not surprisingly, over 60% of
Classification I cases involved the incisal edges of anterior teeth (Rozier 1994).
The acceptance of these fluorosis indices rests largely on the ability of the examiner to
distinguish fluoride- induced changes in the enamel from those that are not fluoride- induced
(Table 6).
Opaque white lines or clouds- chalky appearance
Always on homologous teeth
Usually centred in smooth surface
Round or oval
surfaces
Table 6: Comparison of characteristics of Dental Fluorosis and NOB- Fluoride Enamel Opacities
There is little epidemiological evidence that opacities characteristic of dental fluorosis can be
caused by other factors (Rozier 1994). Trace elements other than fluoride have been
53
investigated, yet only two human studies have shown such an association. Strontium (Curzon
and Spector, 1977) and Zinc (Butler et ai, 1985) have been associated with fluorosis-like
opacities, but these associations were found to be weak. For example in a study in 16 Texas
communities with fluoride levels in drinking water ranging from 0.2 to 3.3 ppm, water fluoride
was found to be accountable for 32 % of the variation in dental fluorosis, while various metals
accounted for 1% to 6% when considered singly (Segreto et ai, 1984). While there is no direct
evidence, the accuracy of fluorosis diagnosis may be as high as 95% for experienced
examiners who give proper attention to examination methods and the use of differential
diagnostic criteria.
2.8.1.2 AESTHETIC PERCEPTIONS OF FLUOROSIS
Knowledge of people's aesthetic perceptions of fluorosis is incomplete arid relatively few
studies have assessed it Some studies which have assessed people's aesthetic perceptions of
dental fluorosis, suggest that concerns may be greater than previously believed (Levy et al
2002). Other studies however, have observed that although the parents and children with teeth
affected by dental fluorosis perceive the presence of a change in tooth colour, associated with
fluorotic lesions, which was more obvious with TF scores of 2 or 3, this was not related to
unattractiveness of teeth. Children with a TF score of 1 were even more likely to perceive their
teeth as Attractive or Very attractive compared with children with a TF score of 0 or 2-3. The
latter two groups were similar in perceived attractiveness of their teeth (Loc and Spencer
2007). This finding was similar to that reported by Ellwood and O'Mullane (1995), Hawley et
al (1996) and Sigwjons et aI (2004). Hawley et al (1996) reported that TF scores of 1 or 2 even
enhanced the appearance of teeth as perceived by children. This phenomenon may be
54
explained by the preference for more ''whitish'' tooth colour of deciduous teeth over
''yellowish'' colour of newly erupted permanent teeth during the mixed dentition period.
The risk of perceived aesthetic problems attributable to fluoridation must be weighed against
its lifetime benefits and the associated costs of alternative solutions (Griffm et at 2002). The
pennanent maxillary incisors are the teeth on which most aesthetic perceptions are based.
No studies about aesthetic perceptions of fluorosis have been carried out in the Maltese
islands.
2.8.1.3 TREATMENT OPTIONS FOR DENTAL FLUOROSIS
Treatment options for fluorosis vary and will depend in part on the severity of the fluorosis
and what the patient can afford (some of the treatments are very expensive). Some of the
more common treatments include:
Micro-abrasion: micro-abrasion involves finely sanding off the outer layer of the enamel.
It is a common approach when the fluorosis is mild. However, if the fluorosis is of a more
advanced severity, abrasion is not a ~ood idea as it can bring to the surface of the teeth
highly-porous enamel that will be prone to attrition.
Tooth Whitening: Tooth whitening does not remove the white lines caused by dental
fluorosis, but lightens the background, thus making the lines less noticeable.
Composite bonding: Composite bonding first involves lightly roughening the area of the
damaged enamel. After etching the enamel, a composite resin (with a colour matching your
teeth) is cured on to the exterior of the tooth.
Porcelain veneersllaminates: Made out of porcelain, veneers form a ceramic shell over the
labial surface of the tooth. The tooth needs to be prepared by removing a thickness of about
55
2mm from enamel and dentine from the labial surface. The veneer will then be bonded to
the remaining tooth by means of an appropriate adhesive and will look like part of the
tooth. Veneers may need to be replaced after several years, however, which can become
quite expensive. They also require a certain amount of dental tissue loss in the preparation
of the tooth.
Porcelain crowns: Porcelain crowns cover the whole tooth and thus disguise the tooth
structure underneath. The tooth needs to be prepared by removing a thickness of about
2mm from enamel and dentine on all the tooth surfaces. The crown will then be constructed
in a dental laboratory, from an impression of the preparation, and bonded to the remaining
tooth by means of an appropriate adhesive. Crowns may need to be replaced after some
years, since their lifespan ranges from five to fifteen years, which can become quite
expensive. They also require a certain amount of dental tissue loss in the preparation of the
tooth for crown construction.
2.8.1.4 EVIDENCE OF DENTAL FLUOROSIS IN GOZO SO FAR
Evidence of dental fluorosis had been found among some school children in Gozo in 1964
(Vassallo, 1968). However no data were ever collected or presented during that period. The
first documented data on dental fluorosis was in 1986. Table 8 shows the distribution and
severity of dental fluorosis in 12 year old children in Malta and Gozo in 1986.
Gozo had the lower percentage of children who recorded nonnal (46.3%). There would appear
to be more fluoride in Gozo as the level of questionable fluorosis is highest, a value of 23.8%
as compared to 3.4% in Malta. However it was only in Malta that children had severe levels of
fluorosis. The percentage of children affected was however very low, 0.8010.
56
Nonnal 62.4 46.3
Questionable 3.4 23.8
Very mild 15.9 15.0
Mild 14.6 8.8
Moderate 2.1 5.0
Severe 0.8 0.0
Table 8: Levels of dental fluorosis in 12 year old children in 1986 - percentage of persons affected (according to the modified Dean's index) (Sources: Moller, 1987; Department of Dentistry - Malta).
Fluorosis occurs during the first 6 years of life, when the teeth are developing. Thus, taking
into consideration the fluoride levels in the public water supplies from 1974 to 1980, which
are the first six years of life of the twelve year old children examined in 1986, one would
expect Gozitan children to have the highest levels of fluorosis. However, the values for Malta
are somewhat higher than expected according to the fluoride concentration in the drinking
water. This suggests that perhaps the clinical signs of dental fluorosis have been slightly
overscored or that non-fluoride opacities (Table 6) have not been excluded (Moller, 1987).
This may, however, also be due to the availability of fluoride from other sources.
Further data was then collected by Vassallo and Portelli in 2004 during the National Oral
Health Survey of the Maltese Islands. The data collected in this survey shows that 21 % of the
children examined in Malta and Gozo had staining of the upper incisor teeth attributable to
57
fluorosis and 19 % of these children were aware of the stains. In Gozo 15 % (9) of the 12 year
old children examined (n=60 12 year olds) had marks attributable to fluorosis.
2.8.2 SKELETAL FLUOROSIS
In rare instances of excessive industrial exposure to fluorides or where natural waters contain
very high fluoride concentrations, particularly when consumed by undernourished or
malnourished population groups, crippling skeletal fluorosis, which is a bone disease
characterised by failure of the bone to mineralise properly, may occur. Fluoride intakes of 10-
25 mg, or more, daily for a period of 10-20 years are required (Hodge, 1979). The bones tend
to be weaker than normal bones and typically the bones of the legs become deformed due to
weight bearing. This disease is characterized by severe osteosclerosis, fresh areas of
osteoporosis, exostoses and calcification of certain ligaments, tendons and muscle insertions
which may result in disability. Skeletal fluorosis is a widespread problem in several
developing countries such as India and Pakistan due to high fluoride exposures mainly from
high fluoride levels in drinking water (up to 18 ppm in 15 Indian states), and hot climates
(therefore increased water consumption).
A number of studies have investigated the fluoride exposure and hip fracture risk. Results vary
with some studies showing a slight protective effect, others a slight increase in fracture rates
and others finding no effect. Mc Donagh et al (2000) conducted a meta analysis of several
studies on bone fracture and water fluoridation and no effects were found except in studies of
10 years or longer, in which case a protective effect of water fluoridation on :fracture risk was
shown.
58
2.8.3 OTHER EFFECTS
A number of other toxic effects and specific health problems have been suggested including
cancer, renal disease, allergies, teratogenicity, allergy and immunological effects, effects on
reproduction, birth defects and other biochemical effects.
"It is a toxic effect and a cosmetic effict. These are not mutually exclusive. It's toxic and it's cosmetic. " - Dr. Arvid Carlsson, Nobel Prize Laureate in MedicinelPhysiology (2000).
There has been a lot of campaigning internationally but especially in the United States of
America against fluoridation.
"Like bones, a child's teeth are alive and growing. Fluorosis is the result of fluoride rearranging the crystalline structure of a tooth's enamel as it is still growing. It is evidence of fluoride's potency and ability to cause physiologic changes within the body, and raises concerns about similar damage that may be occurring in the bones." - Environmental Working Group, 2006.
Special importance is being given to Dental Fluorosis, since it is a systemic effect, with a lot of
theories as to other possible systemic damage caused by fluoride ingested in water.
"A linear correlation between the Dean index of dental fluorosis and the frequency of bone fractures was observed among both children and adults." - Alarcon-Herrera MT, et al. (2001).
These claims to systemic damage have as yet not been adequately supported by enough
evidence from studies and are more theoretical. They are being used by several organisations
who are lobbying in favour of cessation of water fluoridation and against further water
fluoridation. However, considerable evidence has been presented, indicating that fluoride
59
exposure does not represent any carcinogenic or teratogenic hazard, and no effects on
mortality patterns have been detected. Numerous searching reviews of the safety of
fluoridation have been unable to find any adequate grounds for these allegations of harm. The
claim that fluoride played any role in the other problems has never been substantiated (WHO,
2004).
2.9 CONCLUSION
There is no doubt that the use of fluoride decreases dental caries. On the other hand it is clear
that the ingestion of too much fluoride can result in varying degrees of fluorosis. Thus in
practice, the administration should strike a beneficial balance between the two situations.
60
CHAPTER 3 METHODOLOGY
3.1 GENERAL DESIGN OF THE STUDY
This chapter presents and discusses the methods used to carry out the study. The project is an
observational study based on three main sources of infonnation:
A literature review;
A clinical examination of evidence of fluorosis in 5 year old and 12 year old Gozitan school
children;
A question about the aesthetic perception of fluorosis asked to the 12 year old school children.
After approval for the study protocol was given by the Department of Public Health at the
Faculty of Medicine and Surgery of the University of Malta, a request for pennission to carry
out this study was submitted to the Department of Planning and Development of the Education
Division (Appendix 2). Pennission was granted on the condition that approval for the dental
examination is given by parents.
An application for pennission to carry out the study protocol was then submitted to the
Research Ethics Committee. (Appendix 3)
All schools in Malta and Gozo send out consent fonns at the beginning of each scholastic year,
for parents to give signed approval for dental examinations to be carried out for their children
at the school they attend. The children whose parents do not consent to dental examinations
61
are not sent for examinations when dental surgeons or dental hygienists attend to perfonn
screening procedures in the school. In the case of this study, the same conditions applied.
3.2 LITERATURE REVIEW
First, a literature review was undertaken. A critical review of the relevant literature was carried
out in order to provide the scientific basis for the study.
The relevant infonnation was obtained from official and professional organizations, recent
textbooks on preventive dentistry and fluorides, reports from both workshops and meetings,
reviews from different authors and relevant articles and surveys.
The selection of the index used for this study came about after looking at the available tools
reviewed in the literature review. It was decided that the best tool to reach the objectives of
this study was the TF Index since it is sensitive, has high intra examiner reliability, has
reduced examiner subjectivity and does not require a complex examination and could thus be
carried out in schools.
3.3 EXAMINER TRAINING
The examiner underwent training on physical characteristics of fluorosis from the data
gathered in the literature review, photos found on books and on databases of pictures on the
internet, and examination of the details of the TF Index.
62
3.4 STUDY POPULATION
The study populations of 5 year old and 12 year old school children were chosen since these
are the ages at which clinical surveys for oral health are being carried out. This was done so
that comparisons can be made between the results and also to maintain consistency in the age
of reporting. The study was carried out in all the public schools and all the church schools in
Gozo. All the children who had a positively filled consent form and who were present at
school on the day were examined. Other information gathered on examination includes:
• Locality in which the child lives.
• History of relocation up to when child was 6 years of age.
• In the case of the twelve year old school children only, a question regarding stains on
their upper anterior teeth which could not be removed with a toothbrush was asked.
Inclusion Criteria:
• Consent for dental examination from parents.
• Children must be either 5 or 12 years old.
• Children must have lived in Gozo from birth until a minimum of 6 years of age.
• 5 year old children must have a minimum of 6 anterior teeth present which should
be unrestored and should not have smooth surface carious lesions.
• 12 year old children must have a minimum of 6 anterior teeth present which should
be unrestored and should not have smooth surface carious lesions
63
3.5 DATA COLLECTION
3.5.1 FLUOROSIS DATA
A clinical examination of 5 year old and 12 year old Gozitan school children was carried out
using intense light and tongue depressors. The observations were then recorded using the TF
Index (Table 7) which describes the clinical appearance of dental fluorosis. Infonnation as to
the locality where the child currently lives in the case of 5 yr olds and where child lived up to
6 years of age in the case of the 12 year old children was obtained and recorded. The scores
and answers were recorded by a dental hygienist who was acting as a clerical assistant.
pronounced lines of opacity confluence of adjacent lines. Occlusal sUrfaces: Scattered areas of opacity <2 mm in diameter and pronounced opacity of cuspal
entire surface exhibits marked opacity or appears exposed to attrition appear less affected. Occlusal surfaces: Entire sUrface exhibits marked opacity. Attrition is often pronounced shortly after
Smooth surfaces and occlusal sUrfaces: Entire surface displays marked opacity with focal loss of outermost enamel (pits) <2 mm in diameter.
Smooth surfaces: Pits are regularly arranged in horizontal bands <2 mm in vertical extension. Occlusal sUrfaces: Confluent areas <3 mm in diameter exhibit loss of enamel. Marked attrition.
.• 'c;y' •••. '71 Smooth surfaces: Loss of outermost enamel in irregular areas involving <112 of entire sUrface. Occlusal surfaces: Changes in the morphology caused by merging pits and marked attrition.
Smooth and occlusal surfaces: Loss of outermost enamel involving> 112 of surface.
Smooth and occlusal surfaces: Loss of main part of enamel with change in anatomic appearance of surface. Cervical rim of almost unaffected enamel is often noted
Table 7: Clinical Criteria and Scoring for the TF IndeL (fhylstrup- Fejerskov 1978)
64
3.5.2 INTRAEXAMINER RELIABILITY
Intraexaminer reliability was tested. This was done by having the clerking assistant call back
one child, from every group of twenty children seen. The child was then re- examined and re
scored using the TF Index. The scores were recorded and the Weighted Kappa was then
calculated.
3.5.3 AESTHETIC AWARENESS DATA
The 12 year old school children were asked the question "Are you aware of any marks on
your upper front teeth which will not brush oft'?" translated in Maltese to ''Taf jekk
ghandek xi marki fuq snienek ta' fuq ta' quddiem Ii ma jmorrux anke jekk toghrokhom?"
Answers were recorded and divided into the categories: Yes, No and Don't Know.
3.5.4 PUBLIC WATER SUPPLIES
A request for data was sent to the Institute of Water Technology, responsible for the routine
check monitoring programme and the Audit Monitoring Programme (set up to meet the
requirements of Legal Notice 23 of 2004 and 116 of 2004, Food Act 2002), at the Water
Services Corporation to provide information on the fluoride levels in the water supplies of
Gozo. Data on the amount of water coming from the reverse osmosis plants were also
requested.
65
3.6 ANALYSIS AND PRESENTATION OF DATA
The data collected were then entered onto a personal computer.
Statistical analysis was carried out using the SPSS package. Non- parametric tests such as
Kruskal- Wallace test, Mann- Whitney test and Speannan's Correlation were used for
statistical analysis.
The results were presented in graphical and tabular form.
66
CHAPTER 4 RESULTS
INTRODUCTION
This chapter presents the results of the study divided into three sections:
1. Data on incidence of fluorosis of the dental hard tissues in Gozitan school children.
This includes data for the deciduous dentition (obtained from the 5 year old school
children examined) and the permanent dentition (obtained from the 12 year old school
children examined) and the scores given according to the TF Index.
2. Data on aesthetic awareness of fluorosis for the 12 year old age group obtained from
the replies to the question "Are you aware of any marks on your upper front teeth
which will not brush oft'?"
3. Fluoride availability. This includes the fluoride levels in the public water supplies in
the sixteen different localities in Gozo.
4.1 DENTAL FLUOROSIS
4.1.1 RESULTS OBTAINED FOR FLUOROSIS IN 5 YEAR OLD GOZITAN
SCHOOL CHILDREN.
270 five- year old school children were examined for the purpose of this study, out of which
138 were males and 132 were females. 97 (36%) of these children attend church schools and
173 (64%) attend public schools. 28 five year old children were absent or did not have signed
consent forms on the day of the examination (15 females and 13 males). 2 males were not
included in the study as they did not fulfill all the inclusion criteria for this study.
67
In the 5 year age group the percentage of children affected by fluorosis is very low (Figure 9).
Only 8 children (1.8%) had a score on the TF Index, and that score was 1 which is barely
visible to the naked untrained eye (Figure 5). There was no statistically significant difference
between children attending public or church schools (p value 0.072) and between females and
males (p value 0.642) using the Mann Whitney test to analyse the data in both cases. A Non-
parametric test was used since the group analysed (positive for fluorosis) contains a small
number of children.
Zebbug & Marsalfom
Xewkija
Xaghra
Sannat
San Lawrenz
Rabat
Qala
Nadur
Munxar & Xlendi
Kercem
Ghasri
Gharb
Ghajnsielem
Fontana
-\a
'-
~ I
_0
• P
I
o
I
I
10 20 30 40 50
Number of children
Figure 9: TF scores in 5 year old Gozitan school children.
• TF Score 1
o TF Score 0
68
o
4.1.2 RESULTS OBTAINED FOR FLUOROSIS IN 12 YEAR OLD
GOZITAN SCHOOL CHILDREN.
348 twelve- year old school children were examined for the purpose of this study, out of which
177 were males and 171 were females. 80 (23%) of these children attend church schools, 97
(27.9%) attend public secondary schools and 171 (49.1 %) attend public junior lyceum schools.
26 twelve year old children were absent or did not have signed consent forms on the day of the
examination (19 females and 7 males). 5 males and 1 female were not included in the study
due to not fulfilling all the inclusion criteria for this study.
Zebbug & Marsalfum
Xewkija
Xagbra
Sannat
San Lawrenz
Rabat
QaJa
Nadur
Munxar & X1endi
Kercem
Ghasri
Gharb
Ghajnsie1em
Fontana
~ I i;I
b e p
L 8.
i;J.
F===
'" F>.
~l o 10
!
20 30 40
Number of Children
50 60
OTF Score 5
. TF Score 4
o TF Score 3
OTF Score 2
• III TF Score 1
OTF Score 0
Figure 10: TF scores in 12 year old Gozitan school children.
69
13.8% (48) of the children had a TF score of I or more. 23 (6.6%) 12 year old children had
a TF score of I, 11 (3.16%) had a TF score of 2, 10 (2.87%) had a TF score of3, 3 (0.86%)
had a TF score of 4 andl (0.29%) had a TF score of 5 (Figure 10).
There was no statistically significant difference between sexes (p value 0.642) or type of
school (p value 0.072) when using the Mann Whitney test. As in the 5 year olds, a Non-
parametric test was used since the group analysed (positive for fluorosis) contains a small
number of children.
Using the Kruskal Wallis test, the mean TF scores were analysed by locality. A p value of
0.005 resulted making the differences in fluorosis between localities statistically significant.
The 95% confidence intervals of the means were then calculated and are represented in Figure
II below. The upper and lower centiles represent the maximum and minimum values of the
confidence intervals respectively.
1.2'1-----------------------------
! o o
'"
0.8
l!: 06 c .. • :E
0.4
0.2
o
I
I 1 I
I : I
I
I r-
I
il ~ I ~ r 1 r ~ r r -,
J 0 I . 1
Locality
Figure 11: Mean TF scores with their confidence intervals by locality.
70
This bar chart shows that the mean TF score of Xaghra, which is the locality with the
highest fluorosis, is significantly higher than that of all the other localities apart from
neighbouring Zebbug (including Marsalforn) and Gharb.
Figure 12 shows the Mean TF scores of localities plotted on a Gozo map. The localities of
Xaghra, Zebbug and Marsalforn and Gharb on the North West of the Island are the worst
affected area with Qala in the East following closely behind. This pattern does not follow
the same pattern as the fluoride levels in water (Table 9).
• R.. ... B:\T 01C10Rl. ... )
.xn\1aJA
)I~&:'! TF xor~ .~ - .S
• GH. ... ,r..;SIllOI
Figure 12: Map of Gozo showing Mean TF scores by Locality.
71
4.1.3 RESULTS OBTAINED FOR INTRAEXAMINER RELIABILITY.
31 children were re-examined to check intraexaminer reliability. The examiner was blind to
the first TF score obtained by the previous examination of the child. The first reading and
the second reading matched in 100 % of cases, thus giving a Weighted Kappa Value of 1.
4.2 AESTHETIC AWARENESS
Aesthetic awareness of fluorosis was investigated by asking the 348 Gozitan 12 year old
school children about awareness of marks on their upper front teeth which would not brush
off. 38 (11%) of the 12 year old children were aware of marks on their upper incisors which
would not brush off, whilst 289 (83%) were not aware of any such marks on their upper
incisor teeth. 21 (6%) of the 12 year old children did not know if they had any marks on
their front teeth which do not brush off.
From the 38 (11%) children who were aware of marks on their upper incisor teeth only 3
(8%) had marks which could be attributed to fluorosis, with a TF score of 2, 3 and 4
respectively; the others had other enamel opacities which are not classifiable as fluorosis. This
means that only 0.86% of all the 12 year old children examined were aware of marks on their
front teeth which were attributable to fluorosis.
4.3 FLUORIDE AVAILABILITY
Natural fluoride in tap water, which is the most readily available source of fluoride for the
population in Gozo, for the 14 Gozo localities, is shown in Table 9. The fluoride average
for Gozo is decreasing with time, especially since the introduction of the Collection scheme
72
in 2005, which has included polished water into the mixture supplied to all Gozitan
households. The Fluoride levels in the water supply have dropped from 2.5ppm in 1994 to a
mean of 0.94ppm in 2000 and a mean of 0.44ppm in 2006 with an unequal distribution of
fluoride levels between the different localities.
Enamel mineralisation happens mainly at the age of 6 months to 6 years, thus the years
when the fluoride levels in tap water could have systemically affected the 12 year old
Gozitan school children to produce the levels of fluorosis which were found on clinical
examination in 2006, are the years between 1994 and 2000. The correlation between mean
fluoride concentration between 1994 and 2000 and TF scores by locality was analysed
(Figure 13). Spearman's correlation analysis of the data shows no correlation between the
two factors with a resulting p value of 0.68.
0.8
• 0.7 -'
0.6
• 0.5
• ., 0.3
0.2 • • • .. .. 0.1 -A
0~1----------~--------+-~----------~:~,----------~,.~--------~ o 0.5 1.5 2 2.5
Fluoride concentration (ppm)
Figure 13: Graph showing correlation between fluoride concentration and TF scores by locality.
73
-.:t r-
= ~ ~ s! III QC QC g: ~ ~ = = M a ~ ~
III III
~ \C c:I'I c:I'I .
.Q.. = g g = ~ "It ~ c:I'I .... .= =: = . . . u = = =
GI c:I'I t> . ... !::: GI M! M M M = ~ .... . . .= .c ~ .c
~ Q r/.l . M . M M
M
~ GI • ~ !::: ~ ~ ~
I .c
I
~ .c ~ .c .c -= ~ Q.. ~ r: r: .; ....
= - ~ r: = r: fIl
.; = .; ~ 1: ~ 1 -< = GI
~ ~ • I I I I I I ~ ~
0 ~ ~ .c = ..L = ..L = = = ~ = ~ ~ ~ .; ~ .; ~ ~ .; -<
0.90 I 1.63 I 1.33 I 1.57 I 1.20 I 0.94 I 0.86 I 0.75 I 1.20 I 1.03 I 1.41 I 1.04
Table 9: Fluoride levels in water by locality in Gozo in ppm
CHAPTERS DISCUSSION AND CONCLUSIONS
This study has focused on the impact that the prevalence of dental fluorosis has on the
public health in Gozo. It has also focused on the effect that the fluoride content of the public
water supplies in Gozo has had on the level of dental fluorosis in 5 year old and 12 year old
school children, and the aesthetic perceptions of dental fluorosis by the 12 year old school
children. A review of the literature was undertaken to explore the legal and ideal
concentrations of fluoride that should provide significant prevention of dental caries without
causing unaesthetic dental fluorosis.
Although fluorosis is not life threatening, it can cause unnecessary distress to a minority of
the population in its more severe forms, and it is also an economic burden to those citizens
who are affected where aesthetic problems are associated with the more severe forms of
dental fluorosis where reparative restorative treatment is required. The fact that funds
available for health programmes are always limited make it important to determine the types
of programmes that will be the most effective in improving oral health conditions without
any negative consequence, within the limitations of available resources.
5.1 FULFILLMENT OF THE STUDY OBJECTIVES
This section serves to evaluate the fulfilment of the objectives that the study set out to
address.
75
5.1.1 DETERMINATION OF PREVALENCE OF DENTAL FLUOROSIS
IN THE DECIDUOUS DENTmON.
The prevalence of fluorosis in the deciduous dentition has previously never been
determined. The prevalence of dental fluorosis in the deciduous dentition is currently
negligible and this made statistical analysis of the fluorosis data by locality impossible to
carry out for the 5 year olds since the numbers were too small. Ideally these children
should be followed up for fluorosis when they are twelve years old (in 2013) so that
comparisons and analysis of correlation can be carried out between fluorosis in deciduous
and permanent dentition of these same children.
5.1.2 HOW LARGE A PUBLIC HEALTH PROBLEM IS DENTAL
FLUOROSIS IN GOZO CURRENTLY?
This study shows that at present, fluorosis is not a public health problem in Gozo. In
particular, for the twelve year old cohort studied, absence or presence of fluorosis will
remain the same throughout their life, since fluorosis develops between 0 and 6 years of life,
and thus will be valid for the cohort's lifetime.
In the five year old cohort studied, one can only state that negligible fluorosis was recorded
in the deciduous dentition and nothing can be inferred from this result to their permanent
dentition.
Taking into consideration the decreased levels of fluoride in water since the introduction of
the collection scheme, one would postulate that the levels of dental fluorosis in children in
Gozo should decrease even further, thus further decreasing the threat of fluorosis being a
possible public health problem.
76
.J
5.1.3 MONITORING TRENDS OF DENTAL FLUOROSIS
This study serves as a comparison with the available data. When comparing to the data from
1987, one can see a decrease in the levels of dental fluorosis. The fluoride levels in the
potable water supplied to Gozitan households between 1975 and 1981 (when the 12 year
old children examined in 1986 were 0 to 6 years old) are not available. The water supplied
was unpolished ground water, which one can assume was very similar to the kind of water
available between 1994 and 2000 which was studied in this study.
Actual numbers of imports of fluoridated vehicles such as fluoride toothpastes and
mouthwashes are not available for 1975 to 1981, but they would most probably be less than
what was between 1994 and 2000. Therefore this suggests that perhaps in the report
published by Moeller in 1987 the clinical signs of dental fluorosis might have been slightly
overscored or that non-fluoride opacities (fable 6) had not been excluded.
Since dental fluorosis occurs during the first 6 years of life, when the teeth are developing,
taking into consideration the fluoride levels in the public water supplies from 1994 to 2000
(in the case of the twelve year olds) which vary, according to locality, between 0.88ppm and
2.03ppm, one should expect quite a high prevalence of dental fluorosis with high scores in
certain localities where fluoride concentrations exceed 1 ppm. This is in fact not the case as
the results obtained show that the prevalence of fluorosis is 13.8 % with only 4.2 % of the
population having a TF score between 3 and 5 which is considered mild to moderate and no
TF scores higher than 5 were recorded. In the National Oral Health Survey of the Maltese
Islands in 2004, Portelli and Vassallo examined 60 Gozitan children and found 9 of them
77
(15%) with signs on their upper central incisors attributable to fluorosis. The results
obtained in this study are quite similar to this value. The National Oral Health Survey did
not give scores of fluorosis to the children examined so scores could not be compared.
The results of this study also show no correlation between the fluorosis prevalence and the
fluoride levels when analysed by locality. This indicates that the fluoride concentration in
drinking water is not the solitary source from which dental fluorosis is developing and
that other fluoride vehicles are affecting the children with systemic absorption of high
enough concentrations of fluoride, which in addition to the fluoride concentrations in
potable water, cause fluorosis.
This causes questions to arise as to what other fluoride containing vehicle is causing enough
systemic absorption of fluoride in the fIrst six years of life of the Gozitan children to be
causing the level of dental fluorosis found in this investigation and why is tap water not
directly correlated?
There are probably two main reasons for this fInding:
• Increased use of bottled water rather than tap water.
From the National Oral Health Survey of the Maltese Islands (2004),400/0 of the twelve
year old respondents drank only water on a daily basis and 16% drank only water and
something else. 24 % of these children drank bottled water, 31 % drank fIltered tap water
and 45 % drank unfIltered tap water. In the case of the questionnaire sent to parents ofthe
78
5 year old children in the Oral health survey, 55 % of households used bottled water, 6 %
used unfiltered tap water and 35 % used tap water only for making tea or coffee.
• Increased use of fluoridated dentifrices
Fluoride is readily available in the form of toothpastes. A standard tube of toothpaste
contains about 125 grams of toothpaste (generally containing 1500 ppm fluoride). In
Malta 135,523 kg (approximately 1,084, 100 tubes) oftoothpastes were imported in 2006
(NSO) which is a substantial increase from the 458,655 tubes of toothpastes imported in
1995. It is important to note that the data refers to dentifrices in general and not specifically
fluoridated toothpastes.
From the National Oral Health Survey of the Maltese Islands carried out by Portelli and
Vassallo in 2004, only 20% of people use the recommended pea sized amount of
toothpaste when brushing their teeth with 73% using more than the recommended amount
(Figure 14).
Parents should be advised not to use toothpaste when brushing their children's teeth until the
age of2 years. Prior to this age, parents should brush their children's teeth with a toothbrush
and tap water. Professional advice on the use of fluoride toothpaste should be sought where
a child below 2 years of age is considered to be at high risk of developing dental decay.
Parents should also supervise children aged 2 to 7 years when brushing their teeth and
should ensure that only a small pea sized amount of fluoride toothpaste is used and that
swallowing of the paste is avoided.
79
42%
o NO BRUSHING
BRUSHING NO TOOTHPASTE
o PEA SIZED AMOUNT
o HALF BRUSH
• FULL BRUSH
o OVERFLOWING BRUSH
Figure 14: Breakdown of response as to use of toothpaste from the National Oral Health Survey of the Maltese Islands carried out by Portelli and Vassallo in 2004.
Currently, the localities affected most by dental fluorosis are Xaghra, Zebbug and
Marsalfom, Qala and Gharb. Since it has been determined in the results that the levels of
fluoride in the water supply and the levels of dental fluorosis are not correlated, more
investigations need to be carried out into why and what is causing these localities to have a
higher prevalence of dental fluorosis than other Gozo localities.
5.1.3.1 HOW Wll..L THE NEW WATER SUPPLY SYSTEM AFFECT
ORAL HEALTH IN GOZO IN THE FUTURE?
The latest reports on the fluoride content of the public water supply in Gozo, show that the
mean level of fluoride is below 0.5 ppm. This has dropped significantly from the mean
levels of fluoride in the 90s and the early years of this decade where there was a yearly
variability of fluoride levels between 0.75 and 2.5 ppm.
80
The substantial reduction in the fluoride concentration in the tap water is a direct
consequence of the increased production of, nearly fluoride free, reverse osmosis water.
Also, ground water may show variations in the fluoride content depending on the presence
of fluoride containing fonnations at different depths. The ever growing population, the
industrial development, agricultural demands, together with the expansion of the tourist
trade and the increasing standards of hygiene, are putting more strain on the water supplies.
Thus desalinated or polished water is likely to contribute more water to the water supply in
future.
The data from this study will serve for comparisons to be made in the future when studies to
assess the effect of the newly introduced polished water on dental fluorosis are carried out.
These studies should ideally be carried out in 2010, to assess possible changes in fluorosis in
deciduous dentition (5 year olds) 5 years after the introduction of the collection scheme and
get an intennediate reading for the twelve year olds, and in 2017 to assess possible changes
to fluorosis levels in the pennanent dentition due to the collection scheme. Gozo can now be
subdivided into water supply zones for fluorosis comparisons to be done between supply
zones since the fluoride levels tend to vary between different water zones.
5.1.3.2 IMPACT ON DENTAL CARIES
The differences in the fluoride content of the public water supplies are reflected in the caries
levels of the Malta and Gozo. Overall, the data available shows that the caries level in the
Maltese Islands is low. The incidence of dental caries being lower among the Gozitan school
children, than it is among their Maltese counterparts (Figure 14). This implies the possibility
81
that the incidence of dental caries is lower in the Gozitan school children due to the
fluoridated water supply, which Malta currently lacks.
This situation will probably also change, since the current fluoride level in tap water (mean
of 0.5 ppm for Gozo) is insufficient in maintaining oral health. Therefore, there is a good
probability that in time the DMF-T for Gozo will increase and there will be negligible
difference between the trends of Malta and Gozo (2004 trend shown in Figure 15).
4,-----------------------------------------------,
3.5
3
2
1.5
1
--amf! '='IF 010. __ DI.IFT 12 yr olos
Figure 15: shows DMF-T in 5 and 12 year olds (from Portelli and Vassallo 2004) against Fluoride in water in the Maltese Islands. (Sorted by Electoral Districts; Gozo is
District 13)
82
5.1.4 DETERMINATION OF AESTHETIC AWARENESS OF
CHANGES ASSOCIATED WITH DENTAL FLUOROSIS IN
THE 12 YEAR OLD CHILDREN.
The prevalence of fluorosis in the pennanent dentition of twelve year old school children
was also detennined. The whole population was investigated rather than a sample so that
a clearer picture as to the real situation could be obtained. The twelve year olds were
asked a question relating to the aesthetic awareness of changes associated with dental
fluorosis. Only 14 cases of dental fluorosis which scored 3 or more on the TFI index were
found. The level of3 of the TFI scores is considered equivalent to a Dean's Classification
of "mild" and is judged to be a level which may cause aesthetic concern to the patient
(Mc Donagh et al 2000). Out of these 14 cases only 3 children were aware of any stains on
their upper central incisors. The children seem to be greatly unaware of any unaesthetic
changes associated with dental fluorosis and seem to be much more aware of non
fluorotic enamel opacities.
The results obtained from this study show that there is very little fluorosis which can
cause an aesthetic concern to the children in Gozo today.
This cements the conclusion that at this point in time, fluorosis does not seem to be a
public health problem in Gozo, unlike the result that was obtained in the path finder
survey carried out by Moeller in 1986 and published in 1987.
This also correlates with Dean's Findings in 1942, where fluoride at a concentration of 1
ppm in drinking water caused only 'sporadic instances of the mildest fonns of dental
fluorosis of no practical aesthetic significance'.
83
5.2 LIMITATIONS OF THE STUDY
This study has a number of limitations.
• Since a percentage (9.4%) of the 5 year old students were absent there could be a
slight variation in results in the true population.
• Large confidence Intervals in the results were inevitable in this study since such
small numbers of positive fluorosis cases were available.
• Ideally any clinical examination should be carried out in a dental clinic using
compressed air so that the teeth are dry and all defects are clearly visible. This could
not be done in this study since it would be difficult to carry out logistically. For the
examination to be carried out in a dental clinic all the students would have had to be
invited to attend and that would have meant a higher percentage of absenteeism. If
this study had been carried out in a dental clinic, there could possibly be an
increased detection of TF Scores 1 and 2, but would not influence detection of
scores higher than TF 2 and thus would only influence the prevalence but not the
severity of fluorosis.
• The TF Index, although having biological validity and being easy to use, has some
inherent limitations. The distinction between certain scores is quite SUbjective. This
is seen mostly between TF Score 4 and TF Score 5, with both categories being
defmed by marked opacity on the entire smooth surface with some additional
features which are slightly different. This may lead to a level of subjectivity in the
judgement of the examiner in determining how to score the individual being
assessed. In the results obtained in the study there were only 3 children who
84
scored a TF score of 4 and only 1 child who scored a TF of 5, thus this should not
greatly affect the outcome of the study. Also, TF Scores 3 to 5 fall in the category
of Mild to Moderate Fluorosis so any interchangeability between the two scores
mentioned should not greatly affect any result.
Another limitation of the TF 'index is that it is not a continuous scale, but an ordinal
scale and, therefore, the scores should be considered only as arbitrary points along
a continuum of change. A preferred method would be to express the severity of
dental fluorosis in a continuous scale by showing the position of different
observations relative to each other and the extent to which one observation differs
from another. These properties are extremely important when the correlation
between two factors is studied, as well as when evaluating the cause-and-effect
relationship between two variables. Continuous scales for assessing the severity
of dental fluorosis are being created and validated but as yet have not been used in
clinical studies.
The conclusions that can be drawn from this study are that:
• The level of dental fluorosis in Gozo is negligible in the deciduous dentition of
the 5 year olds. Dental fluorosis is low in the permanent dentition of the 12 year
olds and the majority of the fluorosis present is of a mild form. Thus, currently,
dental fluorosis is not a public health problem in Gozo, unlike what was reported
in the path finder survey by Moller in 1987.
85
• The 12 year old children are not aware of the aesthetic changes on their central
incisors associated with dental fluorosis.
• There is a significant difference in the prevalence of dental fluorosis in permanent
dentition when analysed by locality.
• The systemic source of dental fluorosis which is present in Gozo is not singularly
tap water, as was previously assumed, but rather a mixture of the tap water and
the use of other fluoride containing vehicles such as fluoride toothpastes,
mouthwashes and supplements used at an early age when a child is susceptible to
dental fluorosis whilst enamel mineralisation is taking place.
86
CHAPTER 6 RECOMMENDATIONS
Since from this study it is concluded that fluorosis in Gozo is currently not a public health
problem, the following recommendations can be suggested:
• Against a background of exposure to multiple sources of fluoride and changes in
the rates of dental decay, dental fluorosis and fluoride levels in water, it would be
appropriate to define the optimal level of fluoride in the potable water in Gozo on
both a population and individual level, taking account of these altered
circumstances. This would enable a multi sectoral approach to be adopted by the
Government and ideally artificially fluoridate the Maltese Islands' water supply.
This has now become possible due to the new less complicated network of water
supply zones and would be possible if more liaising is done with the Water Services
Corporation. However, since there would surely be some kind of opposition to a
nationwide fluoridation campaign, the consumer's opinion should be sought by
means of a National Referendum prior to any such decisions being made.
Another alternative strategy would be for the government to work with
manufacturers to promote fluoride possibly through bottled water supplies,
especially since there is data to support that nearly one fourth of the population uses
bottled water as its source of drinking water. This would also take into account the
issues of personal choice since consumers can choose whether or not to buy
87
fluoridated bottled water, a choice which is not possible if the potable water system
supplied to households is artificially fluoridated.
• Dental caries and dental fluorosis levels in Malta and in Gozo should be monitored
regularly so that all efforts can be made to reduce any inequalities associated with
them and also to prevent them from becoming oral health black spots. In fact the
Council of European Chief Dental Officers (CECDO) has emphasised the need for
identification of the oral health black spots and a reduction of the inequalities as
priorities for oral health.
Monitoring of dental caries in Gozo will become even more important since the
levels of fluoride in water have decreased, thus probably increasing susceptibility to
dental decay in the future population. Monitoring of dental fluorosis should be
continued both in the deciduous and the permanent dentition so that comparisons
between deciduous and permanent dentition of the same children can be done, and
also so that recent values are always available. These values can be used as a basis
for any Health Promotion campaigns on the correct use of fluoride which would be
required if the level of dental fluorosis is seen to be increasing. Up to date values of
both dental caries and dental fluorosis would be useful for monitoring of trends and
for taking decisions from a public health point of view such as whether it would be
beneficial or not to our population for water to be artificially fluoridated in every
locality on the Maltese Islands.
• Records of importation of toothpastes and other fluoride vehicles need to be
differentiated into fluoride containing and non-fluoride containing vehicles so that
88
changes in both the importation and the use of these vehicles can be monitored. This
is important as it would give an overall view of the exposure to fluoride from
different sources and could be used to prevent an increase in the prevalence of dental
fluorosis. In particular, fluoridated dentifrice, fluoride mouthwash and fluoride
supplement sales should be monitored separately for the islands of Malta and Gozo.
• Further research on fluorosis should be carried out regularly with questionnaires sent
out to parents so as to determine tap water consumption, fluoride habits in
toothbrushing, and the possible use of other fluoride vehicles such as fluoride
supplements or fluoride mouthwashes. This could also become part of the
questionnaire used to carry out the National Health Survey, which is carried out by
the Department of Health Information every five years.
89
)
APPENDIXl DEFINITIONS
Ground water is defined as any water occupying openings, cavities and spaces in rocks.
There are two main sources of such water:
* Juvenile water which rises from a deep magmatic source
* Meteoric water which is due to rainfall having soaked into the underlying rock
Surface Water is water collecting on the ground or in a stream, river, lake, or wetland.
Surface water is naturally replenished by precipitation and naturally lost through
discharge to the oceans, evaporation, and sub-surface seepage into the groundwater.
Surface water is the largest source of fresh water.
Tap water in this text means any natural or artificially produced water or a mixture of both,
which is certified fit to drink by the water works department and supplied to location by
means of a Government's main system.
Polished water in this text means water which has been purified and filtered by means of a
reverse osmosis polishing plant.
90
)
APPENDIX 2 REQUEST FOR RESEARCH IN STATE SCHOOLS
Dim;;oni ta'1-Bdubzzjoni Dipartiment la' I-Ippjmar u tvilupp n-FurjIlJla MALTA
Edw:ation 1)ivjsi0ll Dc:putmc:at of Planning FlorillJla
Request for Research in State Schools
Ar. (PIMu _lUOCK I.EITUS)
Surname: .l~N:tO ..... ?'-.f}.~@. ... Name: ........... f..mg;l,,, .......... .
I.D.CardNumbef: .•. Q9..l3B.c~.) ........ : Telephone: .... ~!1:9..1.~ ...... .
Address·····~8~·· .. ····T.r.~~····c.:~~r.y,..o.··············· .. · .... · .. · ....................... . ..................... ~~~~................................. PostCode.~.tQ
Faculty. M~~ .. ~.~~{1 Course: }A.~.%li~ ... ~fh. Year: .... 4-: .. (~) AreJJ/s of research: ... ~~::~§Tf?:'f ................................ .............................................. .
Aims ~fresean:h: (Underline as appropriIIte) Long Essay Dissertation ~ Publication . Oc..+-~
Estimated duration of research: .S~~~~. ..... Language used: .•. ~ .. l.~ \LsI.-)
Description of method to be used: ... ~.!?~.~ ... ~~~ ..... ~~.!,V.Q~~ .... ~ .. ~.l.ili~~'\ ... ~ ... ~$,.Q •• f.?d.:.f.?r~~ ...... ~~.~:.~'!~!=!O ........................ .
SchooVs where reseMch is to be carried out: .... ~~ ... ~ ... t1?~ ... .p.:!~ ........ ~ ... ~~~~............... . .................................................... .
Years I Forms: .~.L~.~1-.~.t-"":1 Age range of students: .~:{q.~ .. ~: .. 9:· ...
I accept to abide by the rullllIId reguIdOns IV RaadI in SI* Sc:hooIIIIId to CCJn1IIY willi the Data PnJtedIon Ad. 2001.
Wl!nlnq to l!II!!icIntI-Arrt faR staIIment,. rniINprIIInIIII of COIICtIIImInt 01 matinJ fIc:t 011 this form or fir! document preI8IIt.d In IIIpport of this appIclllicla INIY be grounds for crlninal prosecution.
si_or_ ...... 'l/Iiilt .............................. D ... ,05Pb ·,Db
DPIDI2OO3· Rcsean:h &: PllDlling
91
B. Tutors Approval (where applicable)
The above research work is being carried out under my supervision.
, ~\JU\ ~~AU.O . Tutor s Name: ........................ SIgnature ....... .. ( hi bIod; l«ten )
C. Education Division - Official Approval
00nIUItant c)eota\ Public Health
Official Stamp
The above request for permission to cany out research in State Schools is hereby approved according to the official rules and re~tioDS. c! _ \ _ " 0 l\.a 1\ ,.., n • ~ -. • ~~~~ ~~ ~~,~~0fH'~14
I\:} .J..!lI'to-. ~ Ra~'mond Camilleri
ASSIStIIIt Ditet:tor Reaan:h & Pfanning
Date: 0 I / tJ6 /C6 Official Stamp
Coaditions for tile approvalofa request by a student to grry oat mears. lI'Ork jp Sta1e Se ••
Permission for research in State Schools is Sllbject to the following conditions:
I. The official request form is to be accompanied by a copy of the questioonaire and I or any relevant material intended for use in schools during research work.
2. The original request form, showing the relevant signatures and approval, mUst be presented to the Head of School
3. All research work is carried out at the disaetion of the relative Head of School and subject to their conditions.
4. Researchers are to observe strict confidentiality at all times.
5. The Education Division reserves the right to withdraw permission to carry .out research in State Schools at any time and without prior notice.
6. Students are expected to res1rict their research to a minimwn ohtudents I teachers I administrators I schools, and to avoid any waste of time during their visits to schools.
7. As soon as the research in question is completed, the Education Division assumes the right to a full copy (in print Ion C.D.) of the research WoB: carried out in State Schools. Researchen are to fOl'fI'Ilnl tile copies to the Assistant Direetor Researeh and Plagging, EdIlQtio. Divisio ••
8. Researchers are to hand a copy of their Research in print or on C.D. to the relative Scboolls.
9. In the case of video recordings, researchers have to obtain prior permission from the Head of School and the teacher of the class concerned. Any adults recognisable in the video are to give their explicit consent.. Parents of students recognisable in the video are also to be requested to approve that their siblings may be video-recorded. Two copies of the consent fonus are necessary, one copy is to be deposited with the Head of school, and the other copy is to accompany the Request Form for Research in State Schools. Once the video recording is completed, one copy of the videotape is to be forwarded to the Head of school. The Education Division reserves the right to request another copy.
DPlDf2003- Research &: Planning 2
92
APPENDIX 3 LETTER FROM UNIVERSITY RESEARCH ETIllCS COMMITTEE
L-UNlVERSITA: T8 MALTA Msida - Malta SKOLA MBDIKA
IIBI'.T~
I L..: Ref=-N=o:~3212006=:=.::-__ --,I ..
IS· Septemba" 2006
Dr Ethel vento Zahra Amaryllis Triq Cicerun Marsaxlokk ZTN 10
Dear Dr Vento Zahra
UNIVERSITY OF MALTA Msida-Malta
MEDICAL SCHOOL
Please refilr" to your' ~ submitted to the Research Ethics Committee in CODDeCtion with your research entided:
AN ASSESSMENT OF DENTAL FLUOROSIS IN GOZO
The University Research Ethics Committee at its meeting of 14'" July approved the abov&-mentioned Protoool. .
Yours sincerCly
Dr M Vassallo Cbairmao Research Ethics Committee
TEL: (356) 21333903-6. 21336451 CABLES: UNIVl!JISI1Y-MALU TELEX: <1117 HIEDUCMw FAX: (356) 21336450 MEDICAL SCHOOl., GWAIlDAMANGIA TEL: 21221019. 212m1l3 PAX: (0103'56) 21235638
93
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