SALIVA BY DR. SHASHWATI PAUL Ist YEAR PG DEPT. OF PERIODONTICS

Introduction Embryology Salivary glands Mechanism of saliva formation Nerve supply Composition Characteristics of saliva Salivary gland secretion Factors affecting saliva flow rate Functions of saliva Saliva sample collection Saliva as a diagnostic tool Role in oral disease Xerostomia Role in salivary gland diseases Salivary gland diseases Role in periodontics Conclusion References

Saliva is the principal protector of the soft and hard oral tissues.

When the process of secretion diminishes, the oral tissues become susceptible to infection and the ability to masticate, swallow, speak and taste may be disturbed.

INTRODUCTION

Saliva serves multiple and important functions.

Three major, paired salivary glands produce the majority of saliva: the parotid, the submandibular, and the sublingual glands.

In addition, 600-1000 minor salivary glands line the oral cavity and oropharynx, contributing a small portion of total salivary production

EMBRYOLOGY OF SALIVARY GLANDS Salivary glands develop as outgrowths of the

buccal epithelium. The outgrowths are at first solid and later

canalized. They branch repeatedly to form the duct

system. The terminal parts of the duct system

develop into secretory acini. As the glands develop near the junctional

area between the ectoderm of the stomatodaeum and the endoderm of the foregut,it is difficult to determine if they are ectodermal or endodermal.

The outgrowth for the parotid gland arises in relation to the line along which the maxillary and mandibular processes fuse to form the cheek.

It is generally considered to be ectodermal. The outgrowths for the submandibular and

sublingual arise in relation to the linguo-gingival sulcus.

They are usually considered to be of endodermal origin.

One or more of the salivary glands may sometimes be absent.

MAJOR SALIVARY GLANDS

Parotid Sub-mandibular Sub-lingual

PAROTID GLAND Largest of all the salivary

glands Purely serous gland which

produces thin, watery, amylase rich saliva

Superficial portion lies in front of the external ear and deeper portion lies behind the ramus of the mandible

Stensons duct Opens out adjacent to

maxillary second molar

It is 5.8 cm in the craniocaudal dimension, and 3.4 cm in the ventral-dorsal dimension.

Weight is 14.28 g. It is irregular, wedge shaped, and unilobular.

Stenson’s duct arises from the anterior border of the Parotid and parallels the Zygomatic arch, 1.5 cm inferior to the inferior margin of the arch.

Stenson’s duct runs superficial to the masseter muscle, then turns medially 90 degrees to pierce the Buccinator muscle at the level of the second maxillary molar where it opens onto the oral cavity.

SUBMANDIBULAR SALIVARY GLAND

Second largest salivary gland

Produces 65-70% of total saliva output

The duct is called Wharton’s duct

Wharton’s duct exits on the floor of the mouth opposing the lingual surface of the tongue

Located in a depression on the lingual side of the mandibular body

Innervated by parasympathetic nerve endings and possesses no sympathetic receptors

The parasympathetic fibers arrive through the facial and glossopharyngeal nerves

Mixed secretion – mostly serous

SUBLINGUAL SALIVARY GLAND Smallest of the major glands

Produce less than 5% of total saliva output Saliva delivered via the ducts

of Bartholin The Bartholin ducts exit on

the base of the lingual surface of the tongue

Innervated by parasympathetic fibers

Little or no sympathetic influence

Mixed secretion – mostly mucous

Minor salivary glands are found throughout the mouth: – Lips– Buccal mucosa (cheeks)– Alveolar mucosa (palate)– Tongue dorsum and ventrum – Floor of the mouth

Together, they play a large role in salivary production

MECHANISM OF FORMATION OF SALIVASaliva is formed in 2

stages :

  A primary secretion

occurs in the acini

Then modified as it passes through the ducts

NERVE SUPPLY The secretion of salivary glands is exclusively

under nervous control. The gland is supplied by both

parasympathetic and Sympathetic nerves. Parasympathetic are primarily concerned

with the secretion of saliva.

When sympathetic nerve fibres are stimulated , it causes vasoconstriction and contraction of myoepithelial cells around the secretory end pieces and intercalated ducts.

This contraction forces the saliva into main ducts.

PARASYMPATHETIC: It exerts the dominant role in salivary

secretion, and produces a prompt and abundant flow of watery saliva that is rich in enzymes.

SYMPATHETIC: It produces a much smaller volume of thick

saliva that is rich in mucus. So the mouth feels drier then usual in stressful

conditions.

Salivary secretion is enhanced by two different types of salivary reflexes:

1. Simple or unconditioned reflex.

2. Acquired or conditioned reflex.

SIMPLE or UNCONDITIONED REFLEX:

It occurs when chemoreceptors and pressure receptors within the oral cavity respond to the presence of food.

On activation these receptors initiate impulses in afferent nerve fibers that carry the information to the salivary center located in the medulla of the brain.

The salivary center in turn sends impulses via extrinsic autonomic nerves to the salivary glands to promote salivation.

ACQUIRED or CONDITIONED REFLEX:

In this case salivation occurs without oral stimulation.

Just thinking about, smelling, or hearing the preparation of pleasant food initiate salivation through this reflex.

Also called mouth watering. This reflex is a learned response based on

previous experience

COMPOSITION Water content - 99.5% Solids - 0.5%

Inorganic content - 0.2% Organic content - 0.3% Gases -1mloxygen/100ml -2.5ml nitrogen/100ml -50mlcarbondioxide/100ml Cellular elements

CHARACTERISTICS OF SALIVA

Total amount: 1,200-1,500 ml in 24 hours,a large proportion of this volume is secreted at meal time, when the secretory rate is highest Consistency: slightly cloudy, due to presence of cells and mucin

Reaction: usually slightly acidic (ph 6.02-7.05) Specific gravity: 1.002-1.02 

Freezing point: 0.07 –0.34 degree centigrade

SALIVARY GLAND SECRETION Serous: very thin and watery

o parotid glando lingual glands of von Ebner

Mucous: very thick and viscouso palatine glandso posterior lingual glands

Mixed secretions: mix of the twoo Sublingual glands

Mostly mucous with some serouso Submandibular glands

Mostly serous with some mucouso Anterior lingual glands

Mixed secretion

VARIATION OF THE CONCENTRATION OF CONSTITUENTS OF SALIVA WITH THE FLOW RATE

• Substances whose concentration increases as the flow rate

increases: total protein, amylase, sodium bicarbonate

• Substances whose concentration decreases with the increase in

flow rate: phosphate, urea, amino acid, uric acid, serum,

albumin

• Substances whose concentration does not change with change in

flow rate: fluoride

Factors effecting flow rate

A) Diurnal variation: Salivary flow rates exhibit diurnal variation

Protein high in the afternoonSodium and chloride high in the early hoursCalcium high in the night

Nature of stimulusThe stimulus may vary in its effect on different

glands. Variations in composition of whole saliva may arise from differing proportion of the major secretions

Dietary factorsFunctional salivary glandular activity is influenced

by mechanical and gustatory factors e.g. copious salivary flow results from the smell of food or new denture insertion.

FUNCTIONS OF SALIVASalivation and protection

The flow of saliva itself helps wash away the pathogenic

bacteria as well as the food particles that provide their metabolic

support. Glycoproteins and mucoids form a protective coating for the

mucous membrane. It helps in lubrication as a barrier against irritants

acting directly on the membrane .

It also acts as a barrier against the:-

Proteolytic and hydrolytic enzymes produced in plaque

Potential carcinogens (smoking, chemicals, etc,)

Desiccation

Buffering action-

Primary because of the bicarbonate contents and

secondarily because of phosphate and amphoteric proteins,

the salivary ph is usually maintained alkaline. If the

salivary ph falls from alkaline to acidic certain constituents

of saliva get precipitated and get deposited in the form of

tartar thus removing calcium from the tooth and giving rise

to caries.

Facilitation of speech

It is a common observation that activation of words is not clear

when mouth is dry. Saliva lubricates the oral cavity for proper

activation of speech

Mastication and deglutition

Is the act of biting and grinding of food by the movement

of the lower jaw against the upper and is assisted by saliva,

tongue and facial muscles. This helps to convert the food into a

soft bolus.The bolus is coated with a layer of mucous which acts

as a lubricant which facilitates swallowing (deglutition).

Excretory functionHelps in excreting certain heavy metals like lead and iodine etc.

Taste

Any taste, which produces taste sensation, has to be in

solution. Saliva provides the water for this purpose and

thus helps in the appreciation of taste.

Starch digestion

• This is the only digestive function of saliva and is due to

ptyalin, which is a weak amylolytic enzyme.

• It acts on the starch and converts it into maltose.

• The optimum ph necessary for this action is 6.8. The

intermediate products involved are dextrin, erythrodextrin

and Achrodextrin

Maintenance of the tooth integrity –

• Saliva is supersaturated with calcium and phosphate ions that

provides Minerals for posteruptive maturation.

• Provides ions such as calcium and phosphate in sufficient amounts to

counteract tooth dissolution by saliva (solubility product principle).

• It forms a film of glycoprotein on the teeth (the pellicle) that may act

as a diffusion barrier.

Antibacterial factor

Saliva contains inorganic and organic factors that influence bacteria

and their products in the oral environment.

Inorganic factors includes ions and gases, bicarbonate, sodium,

potassium, phosphate, calcium, fluorides, ammonium, and carbon

dioxide

Organic factors include lysozyme, lactoferrin,

myeloperoxidase, lacto peroxidase and glycoproteins, mucins,

Beta-2 macroglobulins, fibronectin, and antibodies

Lysozyme

Is a hydrolytic enzyme that cleaves the linkage between

structural components of the glycopeptide (muramic

acid) – found in the cell wall of certain bacteria

Lysozyme works on gram negative and gram-positive

organisms, Veillonella species and A.A are some of its

targets .

The lactoperoxidase-thiocyanate system in saliva

Is bactericidal to certain strains of lactobacillus and streptococcus by preventing the accumulation of lysin and glutamic acid, both of which are essential for bacterial growth.

Myeloperoxidase

An enzyme similar to salivary peroxidase is released by

leukocytes and is bactericidal for Actinobacillus, but has

added effect of inhibiting the attachment of Actinomyces

strain to hydroxyapatite

Soft tissue repair

• A variety of growth factors and other biologically active

peptides and proteins are present in small quantities in

saliva .

• The presence of nerve growth factor and epidermal

growth factor in the submandibular gland may accelerate

wound healing.

• Many of these substances promote tissue growth and

differentiation, wound healing and other beneficial

effects

Coagulation factors

Saliva also contains coagulation factors VIII, X, XI, plasma

thromboplastin antecedent (PTA) and the Hageman factor

that hasten blood coagulation and protect the wounds from

bacterial invasion.

Vitamins

They are found in saliva, as thiamine, riboflavin, niacin,

pyridoxine, folic acid and vitamin C , B12, and vitamin K

are also reported.

 

Immunoglobulins or salivary antibodies

IgG, IgA, IgM are present

Saliva, like GCF, contains antibodies that are reactive with

indigenous oral bacterial species. IgG is more prevalent in

GCF.

Major and minor salivary glands contribute all of the secretory

IgA (sIgA) and lesser amounts of IgG and IgM.

sIgA constitutes the main specific immune defence mechanism in saliva and may be

important in maintaining homeostasis in the oral cavity.

IgG is primarily derived from serum via GCF and is

present in low concentration .IgG concentration increase

in saliva during inflammation of the periodontal tissue

which causes more severe vascular permeability.

EnzymesEnzymes which increase in concentration in periodontal

disease are hyaluronidase, lipase, B-glucuronidase and

chondritin sulfatase, amino acid decarboxylases, catalase,

peroxidase and collagenase.

Proteolytic enzymes generated by both host and

bacteria. They have been recognised as contributors to

the initiation and progression of periodontal disease, to

combat these enzymes; saliva contains antiproteases that

inhibit cysteine proteases such as cathepsins and

antileucoproteases that inhibit elastase.

Another antiprotease identified as a tissue inhibitor of

matrix metalloprotienase (TIMP) has been shown to

inhibit the activity of collagen.

METHOD OF SALIVA COLLECTION

Passive drool

Oral swab

Spitting method

SALIVA AS A DIAGNOSTIC TOOL

As a diagnostic fluid, saliva offers distinctive advantages

over serum because individuals with modest training further

more can collect it non-invasively, saliva may provide a cost

effective approach for the screening of large populations.

Gland specific saliva can be used for the diagnosis of

pathology specific to one of the major salivary

glands.Analysis of saliva may be useful for the diagnosis of

the hereditary disorders, autoimmune diseases, malignant and

infectious diseases as well as in the assessment of therapeutic

levels of drugs and the monitoring of illicit drug use.

POINT-OF-CARE TESTING

The overall goal of point-of-care (POC) testing is to move salivary diagnostics out of the laboratory and into clinical practice to allow for more timely diagnosis of the disease.

POC testing is testing that can be rapidly performed directly at the dental clinic, without the need for steps such as sending samples to a laboratory.

This process reduces turnaround time, thereby allowing therapy to begin immediately and thus improving the quality of care delivered.

Moreover, by offering immediate results, problems such as patient follow-up can be averted. In addition, these types of tests can lower overall costs, because they will eliminate the need to draw blood and avoid the cost associated with sample shipping and handling to a centralized laboratory.

Bacterial cultural tests Two commercially available salivary bacterial cultural tests are Dentocult

Strip Mutans (Orion Diagnostica, Espoo, Finland) and Ivoclar CRT (Ivoclar Vivadent, Amherst, N.Y.).

Both tests can detect levels of SM and LB, but each test requires a 48-hour

incubation period and a follow-up appointment for discussing the results with the patients.

Salivary SM level test Another test, Saliva-Check Mutans (GC America), resolves the recall

issue as the test can detect salivary SM levels chairside in 15 minutes

Salivary buffer capacity test The Dentobuff Strip (Orion Diagnostica, Espoo, Finland) is a

chairside salivary buffer capacity test that consists of pH indicator paper that has been impregnated with acid. Results of the test are then compared to a chart.

CariScreen caries susceptibility test ATP bioluminescence can assess an individual's risk for caries by

measuring the overall level and activity of cariogenic bacteria. ATP bioluminescence is a simple chairside test that involves

swabbing a specific site on teeth and then a 15-second measurement with a meter.

An example of an ATP bioluminescence test is the CariScreen caries susceptibility test (Oral BioTech, Albany, Ore.)

For oral squamous cell carcinoma

The University of California, Los Angeles (UCLA) Collaborative Oral Fluid Diagnostic Research Laboratory, led by Dr. David Wong, developed a POC device used to detect oral cancer in saliva.

The test, known as the oral fluid nanosensor test (OFNASET), is a POC, automated, and easy-to-use integrated system that uses electrochemical detection of salivary proteins and nucleic acids and can measure up to eight different biomarkers in a single test in less than 15 minutes.

The OFNASET will screen for the risk of oral cancer to allow for only test-positive patients to be referred for biopsies. The test is expected to detect oral cancer at an earlier stage, when treatment is more effective and less costly.

DIAGNOSTIC MARKERS IN SALIVA:

Saliva is a readily available fluid and contains locally produced microbial and host response mediators as well as systemic markers.

These markers help to analyse the current status of disease activity.

Advantages for use of saliva as diagnostic marker

Can be collected more easily, with non invasive procedures and with minimum patient discomfort.

Salivary diagnostic tests are applicable for screening large populations.

Role in oral disease

The role of saliva in oral disease is most apparent when

salivary flow is markedly reduced

• Pellicle and plaque deposition

• Plaque mineralisation and calculus formation

• Maxillary complete denture

• Dental caries

ROLE OF SALIVA IN ACQUIRED PELLICLE FORMATION:

Most of the organic and inorganic constituents of supra gingival plaque are derived from saliva.

Glycoproteins form the important component of pellicle that initially coats the tooth surface.

The inorganic components of supra gingival plaque such as calcium, phosphorous and trace elements like sodium, potassium & fluoride are derived from saliva.

The hydroxyapatite surface has a predominance of negatively charged phosphate group that binds with positively charged particles in saliva.

These glycoproteins bind with plaque forming bacteria.

Glycoprotein bacterial interactions result in bacterial accumulations on the exposed tooth surface.

Glycoproteins also aid in the maintenance of integrity of dental plaque.

ROLE IN CALCULUS FORMATION:

As the mineral content in the plaque mass increases it gets calcified to form calculus.

It is usually found in the areas of dentition adjacent to salivary ducts.(lingual surface of mandibular anteriors &buccal surface of maxillary posteriors) reflecting high conc of minerals available from saliva in those areas.

Salivary proteins account for 5.9% to 8.2% of the organic content of supra gingival calculus.

Various proteins derived from saliva are glucose, galactose, glucuronic acid, galactosamine.

Plaque has the ability to concentrate calcium 2 – 20 times its level in saliva.

A raise in the Ph of saliva causes precipitation of calcium phosphate salts by lowering the precipitation constant.

ROLE OF SALIVA IN FIXATION OF MAXILLARY COMPLETE DENTURES:

The adhesive action of the thin film of saliva between the denture base and the underlying soft tissues is considered as a principle factor for denture retention.

The physical factors of saliva to be considered are - cohesion

- adhesion      - Surface tension. A thick mucous saliva alters the seat of the denture as it

accumulates between the tissues and the denture.

A thick serous saliva of high surface tension is considered ideal for enough retention.

ROLE OF SALIVA IN CARIES FORMATION: The following are the salivary factors involved-1.Composition - caries susceptibility is inversely

proportional to the salivary phosphate content.A higher organic content in the saliva usually indicates more stable plaque formation.

2. Ph: more alkaline - less decay activity. When the Ph of saliva is lowered the conc of ions

needed for saturation rises. To maintain this saturation the tissues will start

dissolving. Lower the Ph faster the demineralization.

3. Viscosity: serous saliva(low viscosity) predisposes to more self cleansing ability than mucous(high viscosity)saliva.

4. Flow- high quantities of saliva flowing in the oral cavity predisposes to less decay activity.

5. Anti bacterial elements- although found in saliva their anti cariogenicity depends on their nature, conc, and amounts. 

Even when a carious lesion has been formed, saliva can play an important role in preventing excessive decay.

Deposition of minerals (fluorides) from saliva will help in the remineralisation of early enamel lesions.

ROLE IN SALIVARY GLAND DISEASE Investigation of the flow rate and

composition of saliva(sialochemistry) is proving to be of great value in the differential diagnosis of diseases of the salivary glands.

Salivary changes have been noted in inflammatory disease, sjogrens syndrome, sarcoidosis, salivary gland calculi, and enlargement of salivary glands because of alcoholic cirrhosis.

XEROSTOMIA Factors that Affect Salivary Flow

Medication Autoimmune disease (Sjogren’s syndrome) Systemic diseases (diabetes, asthma, kidney,

sarcoidosis, HIV) Stress/anxiety/depression

Radiation therapy to the head and neck 30 Gy = glandular fibrosis (gland can still produce some

saliva) 60-70 Gy = glandular destruction (gland can no longer produce

saliva)

Sympathomimetic medications (stimulate the sympathetic nervous system)

XEROSTOMIA: DIAGNOSIS

SIGNS AND SYMPTOMS

Viscous saliva Sticky saliva Difficulty speaking Difficulty swallowing Halitosis Altered taste Complaint of dryness Complaint of burning mouth, lips, or tongue Altered sense of smell

Increased caries Food sticking to the oral structures Gingivitis Absence of saliva Cracking and fissuring of the tongue Ulceration of oral mucosa No pooling of saliva in the floor of the mouth Recurrent candidal infections Poorly fitting prostheses

ARTIFICIAL SALIVAPatients with xerostomia and hyposalivation can be treated with commercially available oral spray, oral solution, lozenges, adhering disc. Oral SprayOasis: Water, glycerin, sorbitol. hydrogenated castor oil, copovidone, sodium benzoate, carboxymethylcellulose ; ethanol free, sugar free, mild mint flavorAquoral: Oxidized glycerol triesters and silicon dioxide (40 mL); contains aspartame, delivers 400 sprays, citrus flavor Oral SolutionCaphosol: Dibasic sodium phosphate 0.032% monobasic sodium phosphate 0.009% calcium chloride 0.052%, sodium chloride 0.569%, purified water (30 mL); packaged in two 15 mL ampules when mixed together provide one 30 mL dose LozengeSalivaSure: Xylitol, citric acid, apple acid, sodium citrate dihydrate sodium carboxymethylcellulose dibasic calcium phosphate, silica colloidal, magnesium stearate stearic acid adhering discXyliMelts: Xylitol 500mg, vegetable gum, cellulose gum, peppermint, stearate of calcium/magnesium

Xerostomia Caphosol: Swish and spit; not to exceed 10 doses/day Oasis: 1-2 sprays PRN; not to exceed 60 sprays/day Aquoral: 2 sprays PO TID/QID PRN SalivaSure: Dissolve lozenge in mouth PRN; not to exceed 16 lozenges/day XyliMelts: Apply 2 discs before bed, 1 on each side of mouth, in lower or upper part of cheek; during the day, use as

needed; swallow as it slowly dissolves (the tan, dimpled side will adhere to teeth or gums)

Xerostomia Caphosol: Swish and spit, not to exceed 10 doses/day

Oasis: 1-2 sprays PRN; not to exceed 60 sprays/day

Aquoral: 2 sprays TID PRN SalivaSure: Dissolve lozenge in mouth PRN; not

to exceed 16 lozenges/day XyliMelts: Apply 2 discs before bed, 1 on each

side of mouth, in lower or upper part of cheek; during the day, use as needed; swallow as it slowly dissolves .

DISEASES OF SALIVARY GLAND

DEVELOPMENTAL ANOMALIES Aberrant salivary glands Aplasia and hypoplasia Accessory ducts SIALOLITHIASIS MUCOCELE NECROTIZING SIALOMETAPLASIA INFLAMMATORY DISORDERS VIRAL INFECTIONS Mumps Cytomegalovirus infection HIV associated salivary gland disease BACTERIAL INFECTIONS Acute bacterial sialadenitis Chronic bacterial sialadenitis Allergic sialadenitis Sarcoid sialadenitis Sialadenosis SJOGREN’S SYNDROME

SIALOLITHIASIS• Sialolithiasis is the formation or presence of a

calculus or calculi in a salivary gland. • It is most commonly seen in the

submandibular gland and duct (about 80% of cases), then the parotid gland and duct .

• Sialolithiasis is rare in the sublingual gland. • Most stones are solitary, but multiple stones

may be present.

Symptoms:• May be asymptomatic • Dull pain from time to time over the

affected gland • Swelling of the gland• Pain with chewing or swallowing Complications• Oral infection

SIALADENITIS• The salivary glands contain a network of ducts.

Saliva flows through them into the mouth. If the flow is reduced or stopped for some reason, infection can grow. This infection called sialadenitis .

• The most common infection is bacterial.• Sialadenitis is most common in the parotid gland

and the submandibular gland.

Symptoms:• Tender, painful lump in cheek or under chin. • Pus may drain through the gland into the

mouth. • If the infection spreads, fever, chills and

malaise may occur.Complication• Oral infection.• Upper respiratory tract infection.• Upper GIT infection.

ROLE IN PERIODONTICS Saliva exerts a major influence on plaque

initiation, maturation, and metabolism. Saliva flow and composition also influence

calculus formation, periodontal disease and caries.

An increase in inflammatory gingival diseases is seen associated with xerostomia.

CONCLUSION Saliva is a complex secretion that plays a

major role in general and oral health and disease.

It lubricates and protects the structures of the mouth and influences the nature of the oral microbial flora and even the chemical composition of the teeth.

Saliva plays a important role in the formation of plaque and calculus and is therefore intimately related to caries and periodontal disease.

REFERENCES HUMAN EMBRYOLOGY Inderbir Singh 4th edition HUMAN PHYSIOLOGY AK Jain 4th edition HUMAN ANATOMY BD Chaurasia 6th edition PERIODONTICS Grants 6th edition

Carranza’s CLINICAL PERIODONTOLOGY 10th edition Shafer’s Textbook of ORAL PATHOLOGY 6th edition Giannobile W. V, Beikler T, Kinney J S, Ramseier C A, Morelli T, Wong D.T Saliva as a diagnostic tool for periodontal disease: current state and future directions Periodontol 2000 2009;50:52-64

Orban’s ORAL HISTOLOGY AND EMBRYOLOGY