Odontomas: A clinicopathologic study in a Portuguese population

VOLUME 40 • NUMBER 1 • JANUARY 2009 61

QUINTESSENCE INTERNATIONAL

Odontoma is a tumorlike malformation

(hamartoma) that contains odontogenic

epithelium with odontogenic ectomes-

enchyme. Odontoma is the most common of

all odontogenic neoplasms and tumorlike

lesions. Odontomas can be subdivided into

compound and complex types. Odontomas

are usually diagnosed in children and young

adults and have no gender predilection. It is

considered a self-limiting developmental

anomaly and is asymptomatic and diag-

nosed on routine radiographs.1

In this study, cases of odontogenic tumors

were collected from 2 facilities in Porto,

Portugal. Frequency and distribution regard-

ing gender, age, and tumor site were ana-

lyzed and compared with previous reports.

Odontomas: A clinicopathologic study in a Portuguese populationLiliana Faria da Silva, DDS1/Leonor David, DMD, PhD2/

Diana Ribeiro, DDS3/António Felino, DDS, PhD3

Objective: Odontoma is a tumorlike malformation (hamartoma) that contains odontogenic

epithelium with odontogenic ectomesenchyme. Frequency and distribution of odonto-

genic tumor among a Portuguese population were analyzed and compared with previous

reports. Method and Materials: A total of 65 odontogenic tumor cases were collected

from the files of the Department of Pathology of Hospital São João, Porto, Portugal, and

the Institute of Molecular Pathology and Immunology of the University of Porto (IPA-

TIMUP), from January 1993 to December 2006. Of these cases, 48 were retrieved and

analyzed. The final diagnosis of each case was based on the 2005 WHO histopathologic

classification of odontogenic tumors, and to the authors’ best knowledge, the present

series represents the first study on odontomas in a northern Portuguese population.

Results: Of the 65 odontogenic tumors cases, 64 (98.5%) were benign and 1 (1.5%), an

ameloblastic carcinoma, was malignant. Odontoma was the most frequent odontogenic

tumor (73.9%), followed by unicystic ameloblastoma (7.7%) and calcifying cystic odonto-

genic tumor (7.7%). Of the 48 odontomas (26 males and 22 females), 34 (70.8%) were

compound and 14 (29.2%) were complex. Most odontomas (72.9%) occurred in patients

under the age of 30, with a peak incidence in the second decade of life. Twenty-eight

(58.3%) odontomas were in the maxilla and 20 (41.7%) in the mandible (P < .05). Twenty-

eight (58.3%) of the 48 odontomas were associated with 33 impacted teeth, including 31

permanent teeth, 1 primary tooth, and 1 supernumerary tooth. The maxillary central inci-

sor (n = 6; 19.4%) and the maxillary canine (n = 6; 19.4%) were most commonly associat-

ed with odontoma, followed by the mandibular canine (n = 5; 16.0%) and maxillary third

molar (n = 4; 12.9%). Conclusion: This study provides clinical and pathological information

on odotogenic tumors in a nothern Portuguese population. (Quintessence Int 2009;40:61–72)

Key words: odontoma, odontogenic tumor, Portuguese

1Faculty of Dentistry, University of Porto (FMDUP); Institute of

Pathology and Immunology, University of Porto (IPATIMUP),

Porto, Portugal.

2Institute of Pathology and Immunology, University of Porto

(IPATIMUP); Medical Faculty, University of Porto (FMUP), Porto,

Portugal.

3Faculty of Dentistry, University of Porto (FMDUP), Porto,

Portugal.

Correspondence: Dr Liliana Faria da Silva, Rua Dr. Roberto Frias,

s/n 4200 Porto, Portugal. Fax: 351-22-557 07 99. E-mail: lsilva@

ipatimup.pt, [email protected]

Silva.qxd 1/15/09 10:26 AM Page 61

62 VOLUME 40 • NUMBER 1 • JANUARY 2009


da Si lva et a l

METHOD AND MATERIALS

Sixty-five cases of odontogenic tumors were

retrieved from the files of the Department of

Pathology of Hospital S. João, Porto,

Portugal, and the Institute of Molecular

Pathology and Immunology of the University

of Porto (IPATIMUP), from January 1993 to

December 2006. This retrospective search of

medical records included case notes, opera-

tion notes, radiographs and radiology

reports, paraffin blocks for histopathology

review, and follow-up reports.

Cases of odontogenic tumors were ana-

lyzed for the distribution of age, sex, and

tumor site. Slides stained with hematoxylin

and eosin were reexamined by 2 patholo-

gists. In the case of recurrent tumors (unicys-

tic ameloblastoma), the histologic appear-

ance of the original and the recurrent tumors

was compared and considered as a single

case. The diagnoses were reevaluated

according to the criteria suggested by the

2005 World Health Organization (WHO) his-

tologic classification of odontogenic tumors.

Odontogenic keratocysts (keratocystic

odontogenic tumor) were not included in the

study to render results comparable with

those reported in the literature.

Of the 65 cases, 48 were retrieved and

analyzed. Clinical diagnosis of an odontoma

was based on the radiographic appearance

of the lesion. After radiographic identification

of an odontoma, oral surgeons treated the

lesion by surgical excision without preopera-

tive incisional biopsy. The removed speci-

mens were fixed in 10% neutral formalin for

at least 24 hours, demineralized in ethylene-

diaminetetraacetic acid (EDTA) from 16

hours to several days depending on the size

of the specimen, washed in running water for

6 hours, dehydrated, and embedded in

paraffin. The paraffin-embedded specimens

were cut in serial sections of 5 µm and

stained with hematoxylin and eosin. The clin-

ical diagnosis of each case of odontoma was

confirmed by macroscopic and histopatho-

logic examination of the hematoxylin and

eosin–stained tissue sections. The odon-

tomas were further classified into compound

and complex types according to classic

definitions.

Data for age, gender, location of the

lesion, presence of unerupted teeth, treat-

ment, and recurrence were obtained from

information submitted with the biopsy

request and from review of the dental charts

and radiographs. The location of the lesion in

the maxilla or mandible was classified as the

anterior (incisor to canine), premolar, or

molar regions. In some cases, if the lesion

was associated with an impacted tooth, it

was assigned to that area. If the lesion was

not associated with an unerupted tooth, it

was assigned to the region approximating

the center of the lesion.

Statistical analyzes were performed using

chi-square test for categories and Student t

test for continuous variables using Statview

software (Abacus Concepts). Values were

considered significantly different when P was

less than .05.

RESULTS

Frequency of odontogenic tumor and distri-

bution by gender, age, localization, and

tumor size are depicted in Table 1.

Of the 65 cases of odontogenic tumor, 64

(98.5%) were benign and 1 (1.5%), an

ameloblastic carcinoma, was malignant (see

Table 1). Odontoma was the most frequent

tumor followed by unicystic ameloblastoma

and calcifying cystic odontogenic tumor (see

Table 1). Gender distribution (51.0% male,

49.0% female) was not significantly different

between tumor entities (P > .05) (see Table 1).

The age of the patients varied widely

(range 8 to 64 years) with a mean ± SD of

26.0 ± 15.2 (see Table 1). The tumors arose

mainly in young people between the ages of

11 and 20 years. However, none of the age

differences between tumor entities was sta-

tistically significant (see Table 1).

Tumor size varied from 0.5 to 5.0 cm with

a mean ± SD of 2.0 ± 1.2 (see Table 1).

Statistically significant differences were

identified when the frequency of odonto-

genic tumor was related to the site distribu-

tion in the jaws (Table 2). The maxilla was

more frequently involved than the mandible

(see Tables 1 and 2), especially in the anterior




da Si lva et a l

and molar regions (see Table 2) (P < .05).

The most frequent tumors observed in the

maxilla and mandible, mainly in the anterior

region, were odontoma and unicystic

ameloblastoma, with unicystic ameloblas-

toma showing a predilection for the

mandibular molar region (see Table 2).

Calcifying cystic odontogenic tumor was

more frequent in the maxilla (60.0%) (see

Tables 1 and 2), whereas most of the other

odontogenic tumors occurred equally in

both jaws. These differences were statistically

significant (P < .05).

One case of calcifying cystic odontogenic

tumor coexisted with an odontoma (Figs 1a

to 1d).

Of the 48 odontomas (in 26 males and 22

females), 34 (70.8%) were compound and 14

(29.2%) were of the complex type (see

Tables 1 and 3). The mean age ± SD for all

odontomas was 26.0 ± 15.2 years; 22.7 ±

13.7 for compound odontoma, and 29.4 ±

16.1 for complex odontoma (see Table 3).

Most odontomas (72.9%) occurred before

the age of 30 with a peak incidence in the

second decade of life. A similar trend of age

Table 1 Distribution of frequency, gender, age, localization, and tumor size (cm) of odontogenic tumors by diagnostic types

Table 2 Site distribution of odontogenic tumors

Localization†

Total Male Female Age Maxilla Mandible Tumor size(n = 65) (n = 32) (n = 33) mean ± SD (n = 35) (n = 30) mean ± SD

Unicystic ameloblastoma 5 (7.7%) 2 (40.0%) 3 (60.0%) 36.6 ± 13.4 0 (0%) 5 (100%) 3.8 ± 1.1Ameloblastic carcinoma 1 (1.5%) 0 (0%) 1 (100%) 48.0 ± 0.0 1 (100%) 0 (0%) N/ACalcifying cystic odontogenic tumor 5 (7.7%) 2 (40.0%) 3 (60.0%) 32.2 ± 19.9 3 (60.0%) 2 (40.0%) 2.3 ± 0.8Ameloblastic fibro-odontoma 2 (3.1%) 0 (0%) 2 (100.%) 8.0 ± 0.0 1 (500%) 1 (50.0%) 1.6 ± 0.6Odontogenic fibroma 1 (1.5%) 0 (0%) 1 (100%) 15.0 ± 0.0 1 (100%) 0 (0%) N/AOdontoameloblastoma 1 (1.5%) 1 (1000%) 0 (0%) 35.0 ± 0.0 0 (0%) 1 (100%) N/AOdontoma 48 (73.9%) 26 (54.0%) 22 (46.0%) 26.0 ± 15.2 28 (58.0%) 20 (42.0%) 1.4 ± 0.6Calcifying epithelial odontogenic tumor 2 (3.1%) 1 (50.0%) 1 (50.0%) 24.5 ± 16.3 1 (50.0%) 1 (50.0%) 3.2 ± 2.6

(N/A) not available.†P < .05.

Maxilla MandibleAnterior Premolar Molar Total Anterior Premolar Molar Total

Unicystic ameloblastoma 0 (0%) 0 (0%) 0 (0%) 0 0 (0%) 0 (0%) 5 (100%) 5Ameloblastic carcinoma 0 (0%) 0 (0%) 1 (100%) 1 0 (0%) 0 (0%) 0 (0%) 0Calcifying cystic odontogenic tumor 0 (0%) 1 (20%) 2 (40%) 3 1 (20%) 0 (0%) 1 (20%) 2Ameloblastic fibro-odontoma 1 (50%) 0 (0%) 0 (0%) 1 0 (0%) 0 (0%) 1 (50%) 1Odontogenic fibroma 1 (100%) 0 (0%) 0 (0%) 1 0 (0%) 0 (0%) 0 (0%) 0Odontoameloblastoma 0 (0%) 0 (0%) 0 (0%) 0 0 (0%) 0 (0%) 1 (100%) 1Odontoma 16 (33.3%) 7 (14.6%) 5 (10.4%) 28 12 (25.0%) 5 (10.4%) 3 (6.3%) 20Calcifying epithelial odontogenic tumor 0 (0%) 0 (0%) 1 (100.0%) 1 0 (0%) 0 (0%) 1 (100.0%) 1Total 18 (27.7%) 8 (12.3%) 9 (13.8%) 35 (54.0%)13 (20.0%) 5 (7.7%) 12 (18.5%) 30 (46.0%)




da Si lva et a l

distribution occurred in patients with com-

pound odontoma. Complex odontomas also

occurred more frequently before the age of

30 years with a peak incidence in the third

decade of life (see Table 3). The differences

in age distribution between compound and

complex odontomas were not statistically sig-

nificant (P > .05).

Twenty-eight (58.3%) odontomas were in

the maxilla and 20 (41.7%) in the mandible.

These differences were statistically signifi-

cant (P < .05) (Table 4).

Statistically significant differences were

also found in the localization of compound

odontoma (see Table 4). Compound odon-

toma occurred more frequently in the maxilla

than in the mandible, especially in the anterior

and premolar regions; in the mandible, 8

(23.5%) occurred in the anterior and 1 (3%) in

the molar regions. In contrast, complex odon-

toma occurred more frequently in the

mandible, with most occurring in the premolar

region. These differences between overall dis-

tribution of compound and complex odon-

tomas were statistically significant (P < .05).

Fig 1c Macroscopy of the surgical specimen with the cysticcapsule and the odontoma (arrow).

Fig 1a Radiographic aspect of the cystic lesion (arrow) andodontoma (*).

*

Fig 1b Tomographic view of the cyst(arrow) and odontoma (*).

Fig 1d Histology of the calcifying cystwith the typical ghost cell (arrow).

Figs 1a to 1d Calcifying odontogenic cyst coexisting with an odontoma.

Table 3 Age distribution of 48 patients with odontoma

Age (y) All odontomas [n (%)] Compound odontomas [n (%)] Complex odontomas [n (%)]

0–10 5 (10.4%) 5 (14.7%) 0 (0%)11–20 19 (39.6%) 15 (44.1%) 4 (28.6%)21–30 11 (22.9%) 5 (14.7%) 6 (42.9%)31–40 4 (8.3%) 4 (11.8%) 0 (0%)41–50 6 (12.5%) 4 (11.8%) 2 (14.3%)51–60 2 (4.2%) 1 (2.9%) 1 (7.1%)61–70 1 (2.1%) 0 (0%) 1 (7.1%)Total 48 (100%) 34 (100%) 14 (100%)Mean ± SD 26.0 ± 15.2 22.7 ± 13.67 29.35 ± 16.10




da Si lva et a l

Twenty-eight (58.3%) of the 48 odon-

tomas were associated with 33 impacted

teeth, including 31 permanent teeth, 1 pri-

mary tooth, and 1 supernumerary tooth. Of

the 31 permanent teeth, 21 (67.9%) were

located in the maxilla and 10 (32.1%) in the

mandible. No significant association was

found between the presence of an odon-

toma and the inclusion of a permanent tooth

(P > .05) (Table 5).

Most of the impacted teeth were in the

anterior region of the maxilla (n = 14, 45.2%)

or mandible (n = 8, 25.8%) (see Table 5). The

maxillary central incisor and the maxillary

canine were most commonly associated with

odontoma, followed by the mandibular

canine and maxillary third molar. The 26

impacted permanent teeth associated with

compound odontoma were found in the

maxilla in 19 cases (73.0%) and in the

mandible in 7 cases (27.0%) (see Table 5).

The maxillary central incisor (23.0%) and

canine (23.0%) were frequently involved, fol-

lowed by the mandibular canine (15.4%). A

statistically significant association was

observed between compound odontoma

Table 4 Site distribution of 48 patients with odontoma

Table 5 Distribution of 31 impacted permanent teeth associated with odontoma

All odontomas* [n (%)] Compound odontoma* [n (%)] Complex odontoma* [n (%)]

Maxilla 28 (58.3%) 25 (73.5%) 3 (21.4%)Anterior 16 (33.3%) 16 (47.1%) 0 (0%)Premolar 7 (14.6%) 7 (20.6%) 0 (0%)Molar 5 (10.4%) 2 (5.9%) 3 (21.4%)

Mandible 20 (41.7%) 9 (26.5%) 11 (78.6%)Anterior 12 (25.0%) 8 (23.5%) 4 (28.6%)Premolar 5 (10.4%) 0 (0%) 5 (35.7%)Molar 3 (6.3%) 1 (3.0%) 2 (14.3%)

Total 48 (100%) 34 (100%) 14 (100%)

*P < .05.

All odontomas Compound odontoma Complex odontoma

Maxilla 21 (67.7%) 19 (73.0%) 2 (40.0%)Central incisor 6 (19.4%) 6 (23.0%)* 0 (0%)Lateral incisor 2 (6.5%) 2 (7.7%) 0 (0%)Canine 6 (19.4%) 6 (23.0%) 0 (0%)First premolar 2 (6.5%) 2 (7.7%) 0 (0%)Second premolar 1 (3.2%) 1 (3.9%) 0 (0%)First molar 0 (0%) 0 (0%) 0 (0%)Second molar 0 (0%) 0 (0%) 0 (0%)Third molar 4 (12.9%) 2 (7.7%) 2 (40.0%)

Mandible 10 (32.1%) 7 (27.0%) 3 (60.0%)Central incisor 1 (3.2%) 1 (3.9%) 0 (0%)Lateral incisor 2 (6.5%) 1 (3.9%) 1 (20.0%)Canine 5 (16.1%) 4 (15.3%) 1 (20.0%)First premolar 0 (0%) 0 (0%) 0 (0%)Second premolar 0 (0%) 1 (3.9%) 0 (0%)First molar 1 (3.2%) 0 (0%) 0 (0%)Second molar 1 (3.2%) 0 (0%) 1 (20.0%)Third molar 0 (0%) 0 (0%) 0 (0%)

Total 31 (100%) 26 (100%) 5 (100%)

*P = .04.




da Si lva et a l

and impacted maxillary permanent central

incisor (P = .04).

Five impacted permanent teeth were

associated with complex odontoma, with the

maxillary third molar (40%) being the most

commonly impacted tooth, followed by the

mandibular second molar (20%), central inci-

sor (20%), and lateral incisors (20%) (see

Table 5). The single primary tooth associated

with odontoma was the maxillary second

molar. The supernumerary tooth associated

with odontoma was in the mandibular anteri-

or region.

Forty-six (95.8%) odontomas showed no

symptoms and were diagnosed during den-

tal radiographic examination either on a rou-

tine basis (Figs 2a to 2c), after prolonged

retention of a primary tooth (Figs 3a and 3b),

or after failed eruption of a permanent tooth

(Figs 4a and 4b). Jawbone swelling was

present in 2 cases.

All 48 odontomas and the associated

impacted teeth were treated by conservative

surgical enucleation with curettage. No

recurrence of the lesion was observed dur-

ing a follow-up of 1 to 20 years.

Figs 2a to 2c Complex odontoma found in a routine radiologic dental exam-ination.

Fig 2a Clinical view with no signs or symptoms.Fig 2b Radiographic aspect of the amorphous mass of calcified material(arrow).Fig 2c Complex odontoma with no clinical complications (*).

a

b c

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da Si lva et a l

Radiographically, compound odontoma

appeared as a collection of several to numer-

ous toothlike radiopaque structures (Fig 5a),

and complex odontoma as an amorphous,

solitary mass of calcified material (Fig 5b).

Both types of odontoma were often surround-

ed by a narrow radiolucent zone (Fig 6). In 28

cases associated with impacted teeth, odon-

tomas were on the eruption pathway of per-

manent or primary teeth (Fig 7), preventing

the normal eruption of the involved teeth. In

only 3 cases associated with a dentigerous

cyst was an additional unilocular radiolucent

lesion was found in combination with an

odontoma (Fig 8). Root resorption associated

with the odontoma was not noted.

Figs 3a to 3c Odontoma associated with prolonged retention of a primary tooth.

Fig 3a Clinical view showing retention of the maxillary primary left central incisor.Fig 3b Tomographic view showing a complex odontoma (*) composed of an amorphous mass and an impacted maxillary centralincisor associated with a dentigerous cyst (arrow).Fig 3c Radiographic aspect of the odontoma (*) and the impacted maxillary central incisor (arrow).

Fig 4a Compound odontoma (*) associated withfailed eruption of a permanent mandibular firstmolar (arrow).

Fig 4b Compound odontoma (*) associated withfailed eruption of a permanent mandibular canine(arrow).

a b c




da Si lva et a l

Fig 6 Complex odontoma surroundedby a narrow radiolucent zone (arrow).

Fig 5a Compound odontoma composed of a col-lection of toothlike radiopaque structures and animpacted maxillary premolar.

Fig 5b Complex odontoma appearing as anamorphous solitary mass (*), partially obliteratingthe maxillary sinus.

Fig 7 Complex odontoma (*) located on the eruption path-way of a maxillary first premolar (arrow).

Fig 8 An additional unilocular radiolucent lesion(upper arrow) was found with a compound odontoma (*)in combination with a dentigerous cyst (lower arrow)associated with an impacted mandibular canine.




da Si lva et a l

DISCUSSION

Odontogenic tumors originate from the tis-

sues of tooth formation and reproduce, to a

minor or major extent, the inductive relation-

ship between the various components of the

normal tooth germ. Odontogenic tumor con-

stitutes a diverse group of lesions because of

the different degrees of intertissue interac-

tion and various growth patterns.2

The WHO published the first edition of

histologic classification of odontogenic

tumor in 1971 and a revised second edition

in 1992.3 The latter edition is widely used in

studies reporting large studies or isolated

cases of odontogenic tumor. Daley et al

reported 445 cases in Canada4; Chidzonga

et al, 148 cases in Zimbabwe5; Lu et al, 759

cases in China6; and more recently,

Ladeinde et al, 319 cases in Nigeria7 and

Jing et al,2 1,642 cases in China. In 2005, the

WHO published a third edition of the classifi-

cation of odontogenic tumors, which is fol-

lowed in this study.1

In the present study, 65 cases of odonto-

genic tumor over a 13-year period (1993 to

2006) were retrieved and the final diagnosis

of each case was based on the 2005 classi-

fication of odontogenic tumor. Of these 65

cases, 48 were analyzed. To the authors’

best knowledge, the present series repre-

sents the first study on odontomas in a pop-

ulation from Portugal.

Reports vary as to the frequency of odon-

togenic tumor, partly because of differences

in the parameters used by the authors. In this

series, odontoma (73.9%) was the most com-

mon type of odontogenic tumor followed by

unicystic ameloblastoma (7.7%) and calcify-

ing cystic odontogenic tumor (7.7%). The

high frequency of odontoma in the present

study is consistent with data reported by

Jones and Franklin,8 which accounted also

for 73.0%. The prevalence of odontoma

according to several authors ranged

between 20.7% and 59.4%, from studies

from America,4,9–12 Asia,13,14 Estonia,15 and

Turkey.16,17 On the other hand, in most African

series7,18–22 ameloblastoma occurred with the

highest frequency, and odontoma ranged

between 2.2% and 7.7%.

These differences cannot be attributed to

only geographic or ethnic variation; it should

be cautioned that the incidence of odontoma

is underestimated in some populations. Most

odontomas are diagnosed on routine radio-

graphs and do not produce clinical symp-

toms. This may be responsible for the low

incidence observed in African populations,

because most of the patients do not seek

medical consultation unless there are symp-

toms suggesting an obvious pathology. In

addition, treatment in many cases is per-

formed in the dental office and the cases are

not registered or sent to a laboratory for

histopathologic diagnosis.

Apart from odontoma, considered a hamar-

tomatous lesion rather than a neoplastic

lesion, ameloblastoma is the most prevalent

odontogenic tumor according to several

authors, with a frequency that varies between

18.3% and 80.1%, higher than the 7.7% fre-

quency observed in the present series. Daley

et al,4 Tanrikulu et al,17 and Jones and Franklin8

reported lower percentages, ranging between

4.9% and 13.5%, and found this tumor type to

be the second most frequent tumor.

In the present series, gender (male-female

ratio, 1:1.5) and age (mean ± SD, 36.6 ± 13.4

years) distribution of unicystic ameloblas-

toma were similar to those in other reports

(see Table 1).21,23–25 There was a striking

predilection for the mandible (see Table 1),

although maxillary lesions varied consider-

ably from other studies.21,24–28 The predilec-

tion of unicystic ameloblastoma for the

mandibular molar region (n = 5, 100%; see

Table 2) in this study is also consistent with

other studies.6,7,8,11,15,16,18,20,21

It was observed that calcifying cystic

odontogenic tumor constituted 5 cases

(7.7%) of all odontogenic tumors, compara-

ble to that noted by Daley et al in a Canadian

population.4,21,23,25,29 Calcifying cystic odonto-

genic tumors occurred predominantly in

females (60%), and the lesions were concen-

trated in the maxilla (60%) (see Table 1).

The paucity of cases of ameloblastic car-

cinoma—primary type (1 case), odontogenic

fibroma (1 case), and odontoameloblastoma

(1 case) in this series—is similar to that seen

in previous reports.4,7,9,11,12,15,16,18,20–22 As in other

series, calcifying epithelial odontogenic




da Si lva et a l

tumor (2 cases) and ameloblastic fibroodon-

toma (2 cases) were rare (see Table

1).4,7,9,11,18,20,22 In the present study, odontoma

accounted for 73.9% of all odontogenic

tumors. Compound odontomas, 34 (70.8%),

showed a higher prevalence than complex

odontoma 14 (29.2%) (see Table 4). The

number of cases of odontoma in this study is

substantial and may be due to the current

widespread use of orthopantomography in

dental treatments, which has allowed early

diagnosis and enucleation of these tumors.

Previous studies have also demonstrated

compound odontoma as the more frequent

type of odontoma.30–33 Budnick reported a

nearly equal distribution of compound and

complex odontoma.34 In contrast, Slootweg35

and O’Grady et al36 found more complex

odontoma than compound odontoma in

their reports,. The discrepancies between the

prevalence of compound and complex

odontomas in this and previous series may

be due to the use of different criteria to select

the samples for histopathologic diagnosis,

different sample sizes, or racial differences.

In the present series, odontoma occurred

more commonly in males (54.0%) than in

females (46.0%). These results are in keep-

ing with other studies that reported a slight

male predilection (57.1% to 64.5%) for the

occurrence of odontomas.30,34,35

Toretti et al found a nearly equal distribu-

tion of odontomas in male (49.7%) and

female patients (50.3%).33 The relatively

minor discrepancies among these studies

suggest that there is probably no significant

gender difference in patients with odontoma.

In the present study, a mean age ± SD of

26.0 ± 15.2 years was observed for all odon-

tomas, 22.7 ± 13.7 years for compound

odontoma and 29.4 ± 16.1 years for complex

odontoma. Most odontomas (72.9%)

occurred before the age of 30 with a peak

incidence in the second decade of life (see

Table 3). Most previous studies of odon-

tomas also showed a mean age of

patients34,35 or a peak age group30,33,34,37 in

the second decade of life and the rare occur-

rence of odontoma in patients older than 30

years. Furthermore, compound odontomas

are more frequently found at a younger age

than complex odontomas. This tendency

was confirmed in the present study. In this

series, odontomas were predominantly located

in the maxilla (58.3%) (see Table 4). In previ-

ous studies, other investigators have demon-

strated a slight predominance of odontomas

(56.4% to 66.9%) in the maxilla,34–36 corrobo-

rating the present study. Other reports show

a nearly equal distribution of odontomas

(47.0% to 51.2%) in the maxilla and

mandible.30,33,37

In addition, most reports show the maxil-

lary anterior region as the most frequent site

for compound odontoma, as was seen in this

study, and the molar region as the main site

for complex odontoma, unlike this series, in

which complex odontoma occurred more

frequently in the mandibular premolar

region.27,30,32,34,36

Fifty-eight percent of odontomas (28 of

48) were associated with impacted teeth,

which is within the range reported by other

investigators (16.0% to 61.0%).30–32,34,37,38

Twenty-eight odontomas were on the erup-

tion pathway of a permanent or primary

tooth, blocking the normal eruption of the

involved impacted tooth. Kaugars et al37

found that half of all odontomas block the

normal tooth eruption. In addition, Morning38

demonstrated that, although many impacted

teeth were removed with odontoma enucle-

ation, three-quarters of the impacted teeth

related to odontoma erupt after its removal.

In this study, maxillary central incisor (19.4%)

and canine (19.4%) were the most frequently

impacted tooth associated with odontomas,

followed by the mandibular canine (15.4%)

and maxillary third molar (12.9%). Only 1

study39 classified the odontoma-associated

impacted teeth according to tooth type.

Chang et al39 demonstrated that the maxillary

central incisor (27.0%) was the most com-

monly impacted tooth associated with odon-

tomas, followed by maxillary canine (26.0%),

mandibular canine (24.0%), and maxillary

lateral incisor (14.0%).

CONCLUSION

This study provides clinical and pathologic

information on odontogenic tumors and




da Si lva et a l

odontomas in a northern Portuguese popu-

lation for the first time. Some similarities were

observed between the present study and

previous studies. The variation in frequency

among series reported in the literature can-

not be attributed to racial or ethnic differ-

ences, but instead to the criteria applied in

each study and to the different resources

available to detect asymptomatic lesions.

The scarce number of odontoma cases

reported by some authors7,18,19,22 may be due

to the asymptomatic nature of this lesion,

which is most frequently diagnosed by rou-

tine radiographs. Conversely, the high fre-

quency in this Portuguese study may be due

to the widespread use of orthopantomography

in dental treatments, which has allowed early

diagnosis and enucleation of these tumors.

Unlike previous Western series where com-

plex odontomas were most frequently

found in the posterior (molar) region, this

Portuguese series found complex odon-

tomas to be most prevalent in the premolar

mandible. Odontoma is frequently associated

with impacted tooth and occasionally with a

dentigerous cyst. Compound odontoma, in

this series, occurred more than twice as often

as complex odontoma. No recurrence was

found in all odontomas after conservative

surgical removal.

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Odontomas: A clinicopathologic study in a Portuguese population

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