Saliva / orthodontic courses by Indian dental academy

SALIVA

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INDIAN DENTAL ACADEMY

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INTRODUCTIONBeginning in 1950’s whole saliva was evaluated

(antimicrobial properties, role in microbial attachment, mineralization, taste, lubrication)

In 1970’s individual components were isolated and biochemically characterized.

In mid-1980’s investigators began to map functional domains of the constituents.


Saliva has been defined as “the fluid secreted by the salivary glands that begins the digestion of foods”.

Saliva, however, is hardly the simple body fluid, nor does it have the limited function, implied in this definition.

The functions of saliva are best appreciated by individuals having diminished salivary function, or xerostomia (Mandel, 1987).


These individuals suffer from increased caries and periodontal disease; their oral mucosa is constantly irritated and sore; food is difficult to chew and swallow; and taste acuity is impaired.

Saliva is thought to function in part by forming protective tenacious films, or pellicles, on the available oral surfaces.


The “whole” saliva that bathes the oral cavity is primarily a mixture of secretions from the paired major (parotid, submandibular, and sublingual) glands and the numerous minor (labial, buccal, glossopalatine, palatine, and lingual) glands.

While salivary glands are normally not found in the gingival tissues, atopic salivary gland tissue has been reported in gingiva (gingival salivary gland choristoma ; Moskow and Baden, 1986).


Whole saliva also contains bacteria (about 108 to 109 /ml); their products, such as organic acids and enzymes; epithelial cells; food debris; and components from gingival cervicular fluid.


Characteristics Of SalivaConsistency :- slightly cloudy due to presence of mucins

and cells

Reaction :- usually slightly acidic (pH 6.02-7.05).On standing or boiling, it loses co2 and becomes alkaline. This alkaline reaction causes precipitation of salivary constituents, as tartar on teeth or calculus in salivary duct. pH increases with flow rate

Specific gravity :- 1.002-1.012

Freezing point :- 0.07-0.34 degree Celsiuswww.indiandentalacademy.com

Anatomy and physiology

Salivary glands are composed of acini, ducts, and stroma. Acini are composed of two cell types: mucous cells, which secrete the viscous mucins, and serous cells, which secrete a less viscous watery fluid containing Ptyalin

The parotid glands posses exclusively serous cells; the sublingual and minor glands contain predominantly mucus-secreting cells; and the submandibular glands are mixed.


Stimulation of salivary gland tissues results in the release of components contained within the secretory granules into the salivary ducts.

Acinar cells produce the majority of macromolecules and water found in salivary secretions and are involved in salt transport.

Cells that line the secretary ducts also contribute components to the secretions and help regulate the electrolyte content of saliva.


The secretion at this point is isotonic with respect to electrolytes.

As the secretion travels distally, electrolytes are readsorbed from the secretion by ductal cells, resulting in a final secretion that is hypotonic with respect to plasma (Martinez, 1987).


Firstly the sodium ions are actively reabsorbed from the salivary ducts and potassium ions are actively secreted but at a slower rate in exchange for the sodium ions.

Therefore sodium concentration of saliva becomes greatly reduced whereas the potassium ion concentration becomes increased.

The greater excess of sodium absorption over potassium secretion creates negativity of about -70 mm in the salivary ducts and this allows chloride ions to be absorbed passively


Therefore the chloride ion concentration falls to a very low level along with the decrease in sodium ion concentration.

Second, bicarbonate ions are secreted by the ductal epithelium into the lumen of the duct. This is probably an active secretary process


The net results of these active transport processes is that, under resting condition, the concentration of sodium and chloride ions in the saliva are only about 1/7th to 1/10th of their concentration in plasma.

On the other hand, the concentration of potassium ions is about seven times greater than the concentration in plasma and concentration of bicarbonate ions is about 2-3 times that of plasma


The secretion of saliva, or salivary flow, is primarily influenced by unconditioned gustatory and masticatory reflexes.

In addition, salivary flow is affected by secondary factors such as the degree of body hydration, position of the body, circadian rhythms (maximal flow occurring in the afternoon, minimal flow occurring during sleep), psychic and emotional factors, numerous diseases, hormonal factors, and drugs (Dawes, 1987).


Stimulation Of Salivary Secretion


The secretomotor fibers of the salivary glands are parasympathetic fibers that originate from a centre that is known as the salivary nucleus.

The parasympathetic fibers of the parotid gland arise from the inferior salivary nucleus and the fibers of sub mandibular and sub lingual gland arise from the superior salivary nucleus.

The fibers of the parotid gland travels with the glossopharyngeal nerve and that of the sub mandibular and sub lingual gland travels with the facial nerve and then with chorda tympani nerve.

The afferent limb which reaches the salivary nucleus arise from the tongue or it may arise from various other areas


Control Of Salivary Secretion

Spontaneous secretion or resting secretion

Secretion after a stimulus conditioned salivary reflex unconditioned salivary reflex


Daily output of saliva ---- 1 to 1.5 L/day (Mandel, 1988).

Unstimulated or resting saliva constitutes 10% to 20% of the daily production.

Approximately 85% to 90% of stimulated saliva is derived from the parotid and submandibular glands, 5% from the sublingual glands, and 5% to 10% from the minor glands.


During sleep, most of the secretion comes from the minor glands, since the flow from the major glands is negligible

In general, the concentration of proteins in saliva is directly proportional to the flow rate.

In addition, there is wide variation in the concentration of various components between individuals.



METHODS OF COLLECTING SALIVA

Stimulated whole saliva :- it can be collected after asking the patient to chew on paraffin wax, rubber bands, gum base and citric acid (2%).

Mixed unstimulated saliva:-

Draining or spitting method: The subject is asked to collect saliva in the floor of the mouth and then spit into a graduated or pre-weighted test tube.


Suction method : saliva is continuously aspirated from the floor of the mouth into a suitable collection vessel.

Swab or absorbent method : A pre-weighted swab or cotton roll, or a gauze sponge is used to collect saliva and then reweighed after collection


Parotid saliva:-

Modified Carlson-Crittenden device: the device has two chambers, an inner and outer chamber. The inner chamber is placed over the orifice of the parotid duct and the outer chamber is connected to a vacuum squeeze bulb. The bulb is compressed and the inner chamber is placed over the orifice. This chamber is attached to tubing that carries saliva to the collection vessel


Submandibular/sublingual saliva

For combined Submandibular/sublingual saliva, custom made collectors are fabricated. Those device contains a central chamber for collection of submandibular saliva and one or two side chambers for sublingual saliva

Fox et al described a simpler method for collecting Submandibular/sublingual saliva. After blocking the blockink the orifices of the parotid duct, the saliva is collected from the floor of mouth with micropipette.


Minor glands:-

These can be collected by micropipette, absorbent filter paper or strips from the inner surface of lips,palate, or buccal mucosa and quantitated by weight differences or using a periotron device


COMPOSITION

Each salivary gland produces a characteristic and complex secretion consisting of electrolytes, proteins, glycoproteins and lipids, each of which differs significantly from plasma

In fact, an increase in the salivary concentrations of constituents such as sodium, chloride, and serum albumin may be diagnostic for salivary gland disorders wherein the saliva-blood barrier is compromised (e.g., sialadenitis).


Water content :- 99.5%Solids :- 0.5% Inorganic content:- 0.2% Organic content :- 0.3%Gases :- 1ml oxygen/100ml 2.5ml nitrogen/100ml 50ml carbon dioxide/100ml Cellular elements

Contents of GCF



Electrolytes Calcium :

Content of calcium in saliva was determined by Jonsgar (1937).

The principle calcium phosphate salts include :1. Dicalcium phosphate dihydrate2. Octacalcium phosphate dihydrate3. Tricalcium phosphate dihydrate4. Hydroxyapatite phosphate dihydrate


Fluoride :

The fluoride content of saliva is less than that of serum and directly correlated to dietary intake.

The fluoride concentration of dental plaque is however greater than that of saliva.

The additional fluoride probably being derived from enamel surface


Organic Constituents

Carbohydrates :

Glucose is present in very low concentration in saliva.

It becomes elevated in diabetes but still appears at about 1 % of blood concentration.

In addition to glucose, submandibular saliva also contains hexose and fructose with small amount of hexosamine and sialic acid.

The glucose concentration is generally 0.5 mg/100 ml of saliva. www.indiandentalacademy.com

Lipids :

Saliva contains small quantity of diglycerides, trigycerides, cholesterol and cholesterol esters and phospholipids in addition to corticosteroids mainly cortisone.

These lipids may play a role in bacterial adsorption to apatite and plaque microbial aggregation.


Proteins :

The acinar cells are the principle source of protein secretion.

Compared to that in blood, the concentration of protein in saliva is extremely low.

With the increasing flow rate the quantity of salivary protein is found to increase.

The serum protein in saliva may account to 20 %, including IgM, IgG, IgA in addition to some albumin.


Acinar cells tend to produce groups or families of molecules, whereas ductal cells produce single species

Since a family member may exhibit functions similar to, or different from, other constituents within the same family, each family may therefore have multiple functions.



Acinar Cell Proteins

MucinsProline-rich proteins and glycoproteinsHistatinsStatherinCystatins Alpha-amylasesCarbonic anhydrases Salivary peroxidases


Ductal And Stromal Products

LactoferrinLysozyme (muramidase)KallikreinFibronectin Secretory IgA (sIgA)


Major salivary components

Mucin 1 (MG1)Mucin 1 (MG1)sIgAsIgA

Mucin 2 (MG2)Mucin 2 (MG2)LactoferrinLactoferrin

PeroxidasesPeroxidasesAmylasesAmylases

Carbonic anhydrasesCarbonic anhydrasesProline-rich proteinsProline-rich proteins

LysozymeLysozymeStatherinsStatherins

HistatinsHistatins

11 1010 100100 10001000 1000010000Size (kDa)Size (kDa)www.indiandentalacademy.com

Acinar cell families

Mucins : These are high molecular weight glycoproteins that are

more than 40% carbohydrate.

The peptide backbone of mucins contains a high number of carbohydrate side chains, which vary in size, composition and charge (Tabak et al., 1982).

Two chemically distinct mucins have been identified in human submadibular sublingual saliva and have been designated mucin-glycoprotein 1 (MG1) and mucin-glycoprotein 2 (MG2) (Levine et al., 1987).


MG1 has a molecular weight greater than 103 kilodaltons, whereas MG2 is considerably smaller (150 to 200 kilodaltons).

In general, the viscoelastic properties of mucins may aid in the formation of the food bolus for efficient mastication and swallowing.

However, the structural differences between the two mucins indicate that they may participate in different functions.


MG1 may function at hard and soft tissue interfaces to provide a permeability barrier for protection against environment insult and desiccation.

Commensurate with this proposed function, MG1 may also act as a glycoprotein lubricant to minimize abrasion between occluding tooth surfaces.

By complexing with antimicrobial factors in saliva. MG1 may also act as a carrier to localize these protective molecules at tissue-environmental interfaces.


Several studies have shown that bacterial attachment to the tooth surface is mediated by salivary mucins that coat the tooth surface as part of the acquired enamel pellicle.

In contrast, the coating of unattached bacteria by salivary molecules such as mucins may inhibit their attachment to oral surfaces and thus facilitate microbial clearance from the oral cavity.

These interactions appear to be selective and can be mediated, in part, by the mucin’s carbohydrate chains.


Proline-rich proteins and glycoproteins:

This superfamily of some 20 members comprises acidic and basic phosphoproteins and basic glycoproteins that are characterized by an amino acid content containing 75% to 80% proline, glutamine, and glycine (Bennick, 1987).

These molecules also exhibit genetic polymorphism manifested as differences in the number and structure of porline-rich proteins between individuals.


Proline-rich phosphoproteins can bind calcium, have a high affinity for hydroxyapatite, and make up part of acquired enamel pellicle.

In addition, acidic proline-rich phosphoproteins can inhibit the precipitation of calcium-phophate salts and thus protect the tooth surface from demineralization and calculus formation.

A negative correlation was found between the concentration of acidic proline-rich phosphoproteins in whole saliva and dental plaque, suggesting that bacteria in plaque may influence the half-life of these molecules in vivo.


The proline-rich glycoproteins provide lubricating properties on the tooth surface, especially when complexed to serum albumin, a major constituent of gingival cervicular fluid (Hatton et al., 1985; Levine et al., 1987).

The peptide backbone of these molecules may mediate attachment of Actinomyces viscous to the enamel surface, and the carbohydrate portion of the glycoproteins may function to mediate attachment and/or clearance of streptococci (Bergey et al., 1986; Gibbons and Hay, 1988).


Histatins:The histatins are a family of small basic peptides

characterized by a high content of histidine.

At least seven members, one of which is phosphorylated, have been identified; these vary in size from 3 to 5 kilodaltons.

These molecules may also form part of the acquired enamel pellicle and inhibit the precipitation of calcium phosphate salts.


Interestingly, these proteins have recently been shown to display bactericidal and fungicidal activities.

Histatins can inhibit the development of candid albicans from the noninfective vegetative state to the infective germinating form (Pollock et al., 1984; Oppenheim et al., 1988).

Finally, these basic peptides help to maintain a relatively neutral pH in the oral cavity.


Statherin:

Statherin is a tyrosine-rich phosphopeptide containing 43 amino acid residues.

This molecule binds calcium, has a high affinity for hydroxyapatite,, and plays a role in demineralization by inhibiting the precipitation of calcium-phosphate salts (Schlesinger and Hay, 1977).


Cystatins :

These molecules constitute a diverse group of thiol protease inhibitors that are found in several tissues and body fluids, including saliva.

At least seven cystatins are present in human saliva; they differ slightly in molecular weight (14 to 15 kilodaltons), charge, and degree of phosphorylation ( Hashimi et al., 1988).

Their ability to complex with mucins may serve to target cystatins to various oral surfaces where they may play a role in remineralization / demineralization processes and suppress the growth and thiol protease activity of oral pathogens.


Alpha-amylases :

This family, which represents the most abundant enzyme found in saliva, can be divided into either glycosylated or nonglycosylated groups (62 or 55 kilodaltons, respectively).

Each group comprises several isoenzymes that differ on the basis of their charge properties (Zakowski and Bruns, 1985).

It has long been thought that the major role of this calcium-requiring metalloenzyme was the preparation of starches for digestion by hydrolyzing ά 1,4 linkages in glucose-containing polysaccharides to end products of glucose and maltose.


Its ability to inhibit the growth of Neisseria gonorrhoeae, its presence in acquired enamel pellicle, and its capacity to bind streptococcus sanguis suggest a role in oral microbial colonization.


Carbonic anhydrases :

These zinc metalloenzymes constitute a family of at least six distinct isoenzymes and are responsible for the reversible hydration of carbon dioxide.

They probably play a role in bicarbonate formation and thus contribute to the buffering capacity of saliva.


Salivary peroxidases: The salivary peroxidase system consists of the

peroxidase enzyme (at least two species of 78 and 80 kilodaltons), the thiocyanate ion (SCN-), and hydrogen peroxide.

The enzyme catalyzes the oxidation of SCN-), by H2O2, generating highly reactive, oxidized forms of thiocyanate such as OSCN- (Mansson Rahemtulla et al.,1988)


These products have a direct toxicity on a variety of microorganisms, including Streptococcus mutans.

Salivary peroxidase also neutralizes the deleterious effects of hydrogen peroxide produced by a number of oral microorganisms and is effective in reducing acid production by glucose-stimulated dental plaque, and can inhibit glucose uptake by S. mutans.


Anti oxidant capacity of salivaFrom a chemical point of view, oxidation is defined as loss of

electrons from substrate

An oxidant or an oxidizing agent is a substance that accepts electrons and causes another reactant to

be oxidized (Prior & Cao 1999)

An FR is commonly defined as an atomic or molecular species with 1 or more unpaired electrons in its structure and can be positively or negatively charged or electrically neutral. E.g:- radical derivatives of oxygen like O2

-,OH,OOH,RO,ROO,RCOO,RCOOO, etc.

Pro-oxidant is a synonym for ROS, indicating a toxic substance that can cause oxidative damage to biological targets. E.g:- radical derivatives of oxygen + non radical oxygen derivatives like H2O2, HOCL, etc.


From a biomedical point of view, an antioxidant may be defined (Halliwell 1997) as a substance that, when present at low concentrations compared with those of an oxidizable substrate, significantly prevents or delays a pro-oxidant- initiated oxidation of the substrate.

Hence the reaction is as follows:-

ENZYME

OXIDANT + SUBSTRATE FREE RADICAL OR ROS

ROS can cause direct damage to proteins, DNA carbohydrates and lipids. It can also modulate the expression of a variety of immune and inflammatory molecules


Classification of antioxidant

(a) Preventive antioxidants, that suppress the formation of FR (e.g.,superoxide dismutase, catalase, glutathione peroxidase and »S-transferase,carotenoids, transferrin,albumin, haptoglobin, caeruloplasmin).

(b) Radical-scavenging antioxidants: that scavenge radicals to inhibit chain initiation and break chain propagation (e.g., albumin, bilirubin,carotenoids, ubiquinol, uric acid, vit. A, vit. C, vit. E).

(c) Repair and ‘‘de novo’’ enzymes that repair the damage and reconstitute membranes (DNA repair enzymes, lipase, protease, transferase).


Pro-oxidant and antioxidant feature of saliva

Human whole saliva contains a complex peroxidase system, the major components of which include different forms of lactoperoxidase secreted by the salivary glands and myeloperoxidases from PMN.

It should also be taken into account that the GCF is constantly mixed with saliva and its flow increases with gingival inflammation.

Increased GCF flow relates to increased PMN levels which, in turn, contribute to overall peroxidase enhancement by myeloperoxidase activity.


Myeloperoxidase is a chlorine-containing enzyme that catalyzes the oxidation of chloride and reduction of H2O2 to form hypochlorous acid (HOCl), a reactive oxygen species that can induce formation of low molecular weight chloramines with bactericidal potential (Miyasaki 1991).

Myeloperoxidase may accumulate during sleep, when salivary flow is very low, with consequent slow removal of PMN products.

It has been suggested that higher myeloperoxidase levels are present in subjects with severe gingival inflammation, probably owing to the enhanced numbers of PMN which enter the oral cavity (Smith & Yang 1984).


On the other hand, saliva is also rich in antioxidants, mainly uric acid, with lesser contributions from albumin, ascorbate and glutathione (Moore et al. 1994)

It has also been demonstrated that saliva has a role in suppressing the lipid peroxidation of ingested foods (Terao & Nagao 1991).

Uric acid is the major anti-oxidant in saliva accounting for 85% of the total anti oxidant capacity of saliva from both healthy and periodontally compromised patients.


Other antioxidants include transferrin,lactoferrin and caeruloplasmin

In fact, in healthy humans, these compounds enable iron and copper (the two elements involved in the FR production.


Very few published studies investigating the antioxidant capacity of fluids local to the oral cavity.

Moore et al investigated the antioxidant capacity in periodontally compromised patients and found no significant change in the antioxidant capacity between these pts. and healthy controls.

However the authors suggested that a local decrease in the salivary antioxidants might be compensated for by an increased GCF flow.


In another study Chappel (JCP 2004) studied the systemic and local antioxidant capacity in periodontitis and health.

He found that mean levels of serum and salivary total antioxidant capacity (TAOC) were not significantly lower in periodontitis compared to age and sex matched healthy control.

However GCF and plasma TAOC were significantly reduced.


Ductal And Stromal Products

Lactoferrin :-This 76-kilodalton glycoprotein binds two atoms of iron

per molecule, with the simultaneous binding of two molecules of bicarbonate.

Lactoferrin’s probable function in the oral cavity is antimicrobial and may be due in part to its ability to sequester iron.

In addition, lactoferrin may also posses a direct, iron independent, bactericidal effect on various strains of streptococci mediated by an anionic target site for lactoferrin on the surface of these microorganisms (Lassiter et al., 1987).


Lysozyme (muramidase) This 14-kilodalton basic protein can lyse the cell walls of gram-

positive bacteria by hydrolyzing the b 1,4 glucosidic linkages between N-acetylmuramic acid and N-acetylglucosamine peptidogly can constituents.

Lysozyme may also kill bacteria found to be insensitive to its muramidase activity by activating endogenous bacterial enzyme(s) (Pollock et al., 1987).

Complexing of lysozyme to mucins provides a mechanism whereby this enzyme may implement its function at various tissue interfaces. In addition, lysozyme may also aggregate certain bacteria, thus effecting their clearance from the oral cavity. www.indiandentalacademy.com

Kallikrein

Kallikrein is a glycoprotein of 27 to 40 kilodaltons, consisting of a single polypeptide chain.

It is a serine protease that can cleave C-terminal and N-terminal peptides from proline-rich proteins and cystatins, respectively.

This posttranslational processing of acinar cell products takes place in the secretory duct prior to the molecules’ entry into the oral cavity. The functional significance of these events remains to be determined.

It also causes vasodilatation. On secretion it acts on the globulins of interstitial fluid to produce bradykinin which is a stron vasodilator www.indiandentalacademy.com

Fibronectin

Fibronectin, a high molecular weight glycoprotein (450 kilodaltons) is found at cell surfaces, in basement membranes, in extracellular matrices, and in connective tissues, as well as in a wide variety of body fluids, including serum and saliva.

Fibronectin has been identified along the interface between the tooth and the gingival connective tissue, as well as along the junctional epithelium-cementum interface.


Fibronectin on the epithelial cell surfaces may preclude attachment of potential pathogens such as Pseudomonas aeruginosa (Woods, 1987).

In addition, complexing of cell surface fibronectin with salivary molecules (e.g., alpha-amylases) can inhibit the epithelial colonization of gram-negative bacteria such as Escherichia coli (Hasty and Simpson, 1987).


Secretory IgA (sIgA):

sIgA was first demonstrated by Tomasi and Ziegelbaum in 1963

This glycoprotein is the predominant immunoglobulin found in all mucosal secretions, including saliva.

Acinar cells of the parotid and submandibular gland produce glycoprotein known as secretary component or secretary piece.


This, together with IgA, forms specific structural entity, the secretory IgA, which is active on the mucosal surfaces.

IgA leaves the plasma cells as a dimeric molecule.

The two halves of the dimmer are held together by a polypeptide known as the ‘J’ piece.


The dimer then enters the epithelial cells of the striated duct or possibly the acinar cells.

There it joins with these secretory component which acts to stabilize molecule and aids in its release into the lumen of the duct.

Over 90% of IgA in saliva is of secretory variety


It acts as a first line of defense

The ability of SIgA to bind to an antigen is a beneficial process since local aggregation of microorganisms inhibits their adherence to hard and soft tissue and thus hinders subsurface microbial invasion in deeper host tissue.

The presence of local antibody can play a role in viral neutralization, attenuation of viral growth and replication on the oral surfaces and neutralization and disposal of toxins and food antigens.


Cells in the parotid gland are responsible for the majority of the IgA found in saliva (Bienenstock et al. 1980, Nair 1986).

There are two subclasses of IgA: IgA1 and IgA2. IgA1 predominates in serum while IgA2 is found in higher concentrations in external secretions (i.e., tears, saliva and milk; Delacroix et al. 1982).


sIgA levels, which are undetectable in newborns, increase progressively and reach adult values in stimulated saliva by 2–4 years of age, and in unstimulated saliva by 6–8 years of age (Burgio et al. 1980).

The reported concentration of salivary IgA varies with the analytical method, and is influenced by the method of saliva collection and rate of salivary flow


FUNCTIONS OF SALIVALubrication and protectionMaintenance of tooth integrityHelps water balanceHelps heat lossTasteDigestive functionBuffering actionAntibacterial activity Tissue repairSpeech Excretory functionsRole of saliva in pellicle and plaque formation, calculus

formation and development of carieswww.indiandentalacademy.com

Lubrication and protection :

The glycoproteins and mucoids produced by the major and minor salivary glands form a protective covering for the mucous membrane .

This coating is barrier against irritants acting directly on the membrane.

It is also a barrier against proteolytic enzymes and hydrolytic enzymes produced in plaque, potential carcinogens and dessication.

It also has mechanical cleansing actionwww.indiandentalacademy.com

Maintenance of tooth integrity :

It is rich in calcium and phosphate and hence ensures that ion exchange on the tooth surface

It provides minerals for post eruptive maturation, thus there is increased surface hardness, decreased permeability, increased resistance to caries.

It provides ion such as calcium and phosphate in sufficient amount to counteract tooth dissolution

It forms a film of glycoprotein on the teeth, that may act as a diffusion barrier, thus preventing loss of tooth mineral


Helps water balance

When moisture is reduced in the mouth, certain nerve endings at the back of the tongue are stimulated and sensation of thirst arises.

When body water is lost (sweating, diarrhoea, etc), saliva is reduced and thirst is felt. The subject feels the necessity to drink water and thus water balance is restored

Loss of 8 % of body weight results in cessation of salivary flow


Helps heat loss

This is mainly found in animals.

When they become hot or excited more saliva is secreted causing greater loss of heat.


Taste

Taste is a chemical sensation.

Unless the substances be in solution, the taste buds are not stimulated

Saliva acts as a solvent and hence essential for taste


Digestive function:-

Saliva contains two enzymes ptyalin and maltase.

Ptyalin or amylase acts on boiled starch breaking down the big polysaccharide into maltose and triose.

Its optimum pH is about 7.0.

Maltase converts maltose into glucose.


Buffering action Primarily due to carbonate and secondarily because of

phosphate and amphoteric proteins, saliva has considerable buffer capacity. Metabolism of proteins and peptides by bacteria releases ammonia and urea which helps to increase the pH

This proteolytic function occurs in plaque, directed against acidogenic microorganisms and occasionally on the mucous membrane surface, where acids from foods may occur.

Many bacteria require specific pH and hence saliva prevents the pathogens from colonizing by denying the optimal environmental condition, thus preventing caries and periodontal diseases.


Antibacterial activity :

Secretory IgA is effective against a number of viruses and bacteria.

Bacterial cells gets coated with secretory IgA, which have reduced tendency to adhere to teeth and mucous membrane surfaces, hence they may be clumped and be swallowed.

Lysozymes hydrolysis the cell wall of some bacteria.


Lactoferrin has also been found to exhibit a bactericidal effect on cariogenIc streptococci.

Lactoperoxidase- thiocyanate- hydrogen peroxide system have potential of reducing plaque accumulation.

Salivary glycoproteins inhibit the adsorption of some bacterial to the tooth surface and to the epithelial cells of the oral mucosa.


Tissue repair :-

When saliva is mixed with blood then clotting time is accelerated.

A variety of growth factors and other biologically active peptides which are present in small quantities in saliva help in tissue growth and differentiation, wound healing and other beneficial effects


Speech :

It also helps in pronunciation of proper words

Saliva may also lead to :-

Pellicle and plaque deposition Plaque mineralization and calculus formation

Dental caries


Excretory functions:-

Saliva excretes urea, heavy metals, thiocynates certain drugs like iodine,etc.

Alkaloids, such as morphine antibiotics like penicillins, streptomycin are also excreted in saliva.

The secretion of ethyl alcohol by salivary gland has prompted the recommendation that such a test be used in medico-legal cases.


SALIVA AS A

DIAGNOSTIC FLUID



Enzymes

Enzymes present in saliva can be produced by cells in the salivary glands, oral microorganisms, polymorphonuclear leucocytes (PMNs), epithelial cells, and can be derived from GCF entering the oral cavity (Chauncey 1961).

Studies have examined enzyme activity in saliva in relation to periodontal status and in response to periodontal treatment


In a study by Nakamura & Slots (1983), enzyme activity in mixed whole saliva and parotid saliva was examined in 10 individuals with a healthy periodontium,

10 adult periodontitis (AP) patients and 4 localized juvenile periodontitis (LJP/JP) patients.

Mixed whole saliva from AP patients demonstrated the highest enzyme activity, while mixed whole saliva from the healthy controls demonstrated the lowest.

No significant differences in enzyme activity were found between the AP and the LJP groups


Higher enzyme activities were found in the AP patients compared to the healthy controls for alkaline phosphatase, esterase,β-glucuronidase, β -glucosidase, and other aminopeptidases.

Saliva from patients with LJP contained the highest levels of butyrate esterase and cysteine aminopeptidase. Their data suggested that

oral microorganisms contributed to the enzyme pool in saliva.


Zambon et al. (1985) evaluated changes in the levels of enzymes in whole mixed saliva of AP patients before and

after treatment which included scaling, root planing (Sc/Rp) and tetracycline therapy.

Treatment resulted in reduced salivary levels of caprylate esteraselipase, leucine, valine and cysteine aminopeptidases, trypsin, β galactosidase, β glucuronidase and β -glucosidase.


Furthermore, a decrease in proportions of subgingival black pigmented bacteroides and motile organisms were noted after treatment, suggesting that these microorganisms are one potential source of enzyme.

The authors proposed that the effectiveness of periodontal treatment might be monitored by changes in levels of specific bacterial enzymes in whole saliva


Gregory et al. (1992) reported that whole saliva from LJP patients had significantly higher levels of immunoglobulin degrading enzymes than age, gender and race-matched healthy controls.

The authors proposed that production of such enzymes by periodontal pathogens may provide these organisms an ecological advantage.


Fibronectin is a glycoprotein that promotes selective adhesion and colonization of certain bacterial species, while inhibiting others.

Therefore, the production of fibronectin-degrading enzymes by certain bacteria present in dental plaque may promote their adhesion and colonization.

This was investigated by Gibbons et al. (1986) who examined fibronectin-degrading enzymes in saliva from periodontally healthy adults.


Whole unstimulated saliva collected immediately after awakening (representing the absence of oral hygiene measures for 6 to 8 h), and samples which were collected after toothbrushing, were evaluated.

Higher proteolytic activity was observed in saliva collected immediately after awakening, and the levels of enzyme activity correlated with the state of cleanliness.

It was concluded that changes in oral cleanliness may contribute to the rapid fluctuations in salivary proteases and epithelial cell fibronectin.


Nieminen et al. (1993) measured enzyme activity in whole saliva from 24 adults with advanced periodontitis and 25 subjects with a healthy periodontium.

Patients received periodontal treatment and were evaluated longitudinally for 20 months.

After treatment, a decrease was noted in protease levels in saliva.

Using saliva samples collected prior to treatment and after non-surgical therapy, the activity of salivary elastase correlated significantly with the number of deep pockets and the % of bleeding sites


The authors stated that the enzyme activity in whole saliva appears to reflect the severity of periodontal disease, and that salivary elastase has potential as an adjunctive measure to assess periodontal inflammation and the response to periodontal treatment.


General proteolytic activity in saliva, as well as collagenase, elastase-like and trypsin-like activity has been examined in patient with LJP, AP, and healthy controls (Ingman et al. 1993).

Saliva of AP patients demonstrated higher levels of protease, collagenase and elastase like activity in comparison to the LJP patients and the healthy controls.

In the AP patients, Sc/Rp reduced the levels of protease and elastase-like activities.


No significant response to treatment was detected in the LJP patients.

The data suggest that elastase-like activity in saliva would be a simple and accurate indicator of the effectiveness of treatment.


Comparable results were reported by Uitto et al. (1990), who collected saliva from subjects with a healthy or diseased periodontium. Samples were assayed for collagenase activity.

Vertebrate collagenase was detected in whole saliva from all subjects, but not in parotid, sublingual or submandibular saliva.

Collagenase activity was higher in the periodontitis patients than the controls. Very little collagenase activity was detected in whole saliva of edentulous subjects.


For the periodontitis patients, treatment resulted in a significant reduction in collagenase activity.

In those patients the collagenase was mainly in the active form, while in the healthy subjects the enzyme was in the latent form.

The authors stated that while bacterial collagenase may have been present in small quantities, most of the collagenase in the saliva samples originated from PMNs entering the oral cavity through the gingival sulcus.


Sorsa et al. (1990) supported these finding and reported that interstitial collagenases isolated from extracts of inflamed human gingiva, GCF and saliva were derived from PMNs, and not fibroblasts.


Children with Down’s Syndrome have an increased prevalence and severity of periodontal disease (Orner 1976).

Activity of salivary collagenase in 9 affected children, 9–17 years of age, was higher than controls.

It was suggested that the presence of activated matrix metalloproteinase activity derived from PMNs and/or cytokine-activated fibroblasts, may in part be responsible for the early periodontal tissue and alveolar bone destruction seen in patients with Down’s Syndrome (Halinen et al. 1996).


Hayakawa et al. (1994) reported that the concentration of tissue inhibitor of metalloproteinases – 1 (TIMP-1) in whole saliva of patients with periodontal disease was lower, and total collagenase activity was higher, as compared to healthy controls.

Most of the collagenase in whole saliva from the healthy subjects consisted of procollagenase, while active collagenase predominated in saliva from patients with periodontal disease.

Increased TIMP-1 and decreased collagenase activity were observed after initial therapy was provided to the periodontitis patients.


Similarly, Ganbar et al. (1990) evaluated salivary levels of collagenase and gelatinase in 23 patients with AP, and 7 patients with LJP. Active collagenase levels were found to be significantly higher in AP and LJP patients compared with controls.

Following treatment, levels of active collagenase and gelatinase were reduced.

No significant correlations were observed between the clinical indexes (gingival index, plaque index and pocket depth) and enzyme activity, but positive trends were observed.


The authors concluded that measurement of active collagenase and gelatinase in mouthrinse samples is potentiallyuseful in the diagnosis and assessment of periodontal disease.


Levels of salivary gelatinase in relation to periodontal status were also evaluated by Makela et al. (1994).

They determined that the concentration of MMP-9 (92 kDa gelatinase) was significantly higher in whole saliva of periodontitis patients compared with healthy subjects, and that conventional periodontal treatment (Sc/Rp and surgery if needed) reduced the levels of these enzymes.


Ingman et al. (1994) studied the presence and molecular forms of gelatinase in saliva and GCF collected from AP, LJP and patients with type II diabetes melitus and periodontitis.

The gelatinase isolated from saliva and GCF was similar to gelatinase isolated from PMNs and fibroblasts.

It was suggested that multiple forms of gelatinase present in saliva may be involved in tissue destruction


Several studies have evaluated the presence of host-derived non-immune antimicrobial factors in saliva.

The concentration of lysozyme in mixed saliva was examined in 28 patients with severe periodontitis (6-mm probing depths and generalized bone loss) and 28 healthy controls.

Patients with periodontitis demonstrated decreased lysozyme concentration compared to controls (Markkanen et al. 1986).

But the significance was not maintained if secretion rates were analyzed


In contrast, Soumalainen et al. (1996) evaluated myeloperoxidase (MPO), lysozyme an lactoferrin activity in relationship to periodontal disease.

7 patients with LJP and 7 periodontally healthy controls were studied.

The concentrations of lysozyme, lactoferrin and MPO were significantly elevated in peripheral blood PMNs, and in GCF from the LJP patients.


Following periodontal therapy, these values declined and approached those observed in healthy controls.

In a study by Jalil et al. (1993), resting and stimulated whole saliva samples were collected from 94 children (aged 12–14 years), and analyzed for concentrations of thiocyanate, lyzozyme and lactoferrin in relation to plaque accumulation and gingivitis.

An inverse relationship was observed between the salivary thiocyanate concentration in both resting and stimulated saliva and the amount of plaque and gingival inflammation.


The lactoferin concentration in stimulated saliva was directly related to the amount of plaque and severity of gingivitis.

Lysozyme concentration in stimulated saliva was directly related to the amount of plaque.


In an experimental gingivitis study in 8 patients, Smith et al. (1984) demonstrated an increase in peroxidase activity with the onset of inflammation, which declined after normal oral hygiene measures were resumed.

Similarly, salivary peroxidase activity in whole saliva was also measured in a group of 10 patients with insulin dependent (type I) diabetes mellitus (IDDM) with gingival inflammation, and in 10 healthy subjects (Guven et al. 1996).


Salivary peroxidase activity was higher in the diabetes patients, and the authors suggested that salivary peroxidase activity might serve as a marker for gingival inflammation in IDDM patients.

In addition, increased MPO activity was found in saliva of patients with rapidly progressive periodontitis (RPP) and AP patients as compared to controls (Over et al. 1993).

The highest MPO activity was found in the RPP group, suggesting a relationship between MPO activity and the severity of periodontal breakdown.


The increased MPO activity was attributed to increased infiltration and degranulation of PMNs.

In contrast, the concentration of salivary peroxidase was significantly reduced in both whole and parotid saliva from 28 JP patients in comparison with age and gender-matched controls (Saxen et al. 1990).


Furthermore, leukocyte-derived MPO was present in significantly lower amounts in whole saliva from the JP patients.

Based on these findings it was concluded that reduced peroxidase mediated host defense mechanisms could be characteristic of JP.


Levels of the enzyme kallikrein have been studied in saliva.

This enzyme hydrolyzes kininogen to release vasoactive kinin peptides such as bradykinin (Fuji-moto et al. 1973).

These peptides are important mediators of inflammation

Kininogen levels in saliva from patients with periodontal disease were higher than what was observed in saliva from periodontally healthy patients.


In another study, an increase in salivary kallikrein and a decrease in salivary kininase activity were found in association with increased severity of periodontal disease (Picarelli et al. 1986).


Immunoglobulins

Guven et al. (1982) reported that in comparison to healthy controls, higher levels of IgA were present in whole saliva collected from patients with gingivitis and periodontitis.

There was a positive correlation between the severity of inflammation and IgA concentration


Sandholm et al. (1984) evaluated salivary IgA, IgG, and IgM in whole saliva from 21 patients with JP, 27 healthy siblings and 17 age-matched healthy controls.

Salivary IgA, IgG, and IgM levels were higher in the JP patients as compared with the healthy controls

In contrast, Bokor (1997) reported that the concentration of IgA in mixed unstimulated saliva was lower in subjects with more gingival inflammation.


Changes in the concentration of immunoglobulins in saliva following treatment were examined by Reiff (1984).

The salivary (and serum) levels of IgG and IgA were determined in healthy adult patients, and patients with periodontal disease before and following initial periodontal therapy.

A decrease in salivary levels of both IgA and IgG was observed after treatment.


In a study of whole saliva collected from 12 patients with periodontal disease, the IgG concentration in saliva was found to be increased and IgA concentration decreased before periodontal therapy as compared to post-treatment levels (Basu et al. 1976).


Salivary levels of IgG and IgA were found to be higher in a group of 50 NIDDM patients with periodontitis, as compared with 50 non-diabetic periodontitis patients, and 50 age and gender matched healthy controls.

The authors proposed that the altered immune response observed in patients with diabetes may be due to a greater antigenic challenge in the diabetic patients (Anil et al. 1995).


Summary

While sIgA is the predominant immunoglobulin in saliva and is secreted actively, IgG in saliva is primarily derived from GCF and analysis of this isotype holds promise as an indicator of periodontal disease.

Contradictory results were found, however, when levels of salivary immunoglobulins were studied in relation to periodontal status and the response to treatment.


Some studies reported an increase in levels of immunoglobulins with more pronounced periodontal disease (Guven & De Visscher 1982, Sandholm & Gronblad 1984, Sandholm et al. 1987)

while other studies demonstrated decreased levels (Bokor 1997, Schenck et al. 1993).

For IgA, many studies did not differentiate between sIgA and serum derived IgA.


This may explain the contradictory results. Furthermore, the method of collection can affect the results (Aufricht et al. 1992).


Specific immunoglobulins in saliva

Specific immunoglobulins in saliva directed towards periodontal pathogens have also been examined for the diagnostic potential.

Mansheim et al. (1980) evaluated salivary IgA levels to Porphyromonas gingivalis in 8 patients with RPP and 3 patients with JP, and found that antibody levels in saliva samples from patients were not significantly different from those of age matched controls.


Eggert et al. (1987) reported that saliva from treated periodontitis patients had higher IgA and IgG levels than did saliva from control subjects.

These higher antibody levels were observed for periodontal pathogens (P. gingivalis and Treponema denticola), but also for the normal inhabitant of the oral cavity Streptococus


Sandholm et al. (1987) measured specific salivary antibody to Actinobacillus actinomycetemcomitans Y4 in-patients with JP and AP and in healthy controls.

Compared to the concentration observed in subjects with a healthy periodontium, a significantly increased concentration of salivary IgG was found in 34% of the patients with moderate AP, and in 57% of the patients with severe AP.

The level of salivary IgG antibody to A. actinomycetemcomitans was significantly elevated in 55% of the patients with untreated JP and in 28% of the treated patients


In a study by Schenk et al. (1993), salivary IgA levels against oral bacteria were measured in an experimental gingivitis protocol.

As compared to patients with a high bleeding score, patients with a low mean number of bleeding gingival units demonstrated significantly higher levels of salivary IgA antibody reactive with Streptococcus mutans, A. actinomycetemcomitans, and Eubacterium saburreum.


The authors stated that high levels of salivary IgA directed against bacteria in dental plaque might protect against the development of gingivitis.

Similar trends were found by Tynelius-Barthall & Ellen (1985) who measured changes in salivary antibodies to Actinomyces viscosus and Actinomyces naeslundii in 6 patients with gingivitis prior to and after treatment.


Nieminen et al. (1993) reported that the concentration of specific IgG and IgA antibodies to A. actinomycetemcomitans in saliva of patients with advanced periodontitis correlated significantly with corresponding antibody titers in the serum of those patients.

It was concluded that for severe AP patients, saliva samples could be used diagnostically to assess the serum antibody response to A.actinomycetemcomitans.


Proteins Fibronectin is a glycoprotein which mediates adhesion

between cells and is also involved in chemotaxis, migration, inflammation, and wound healing and tissue repair.

In a study by Lamberts et al. (1989), salivary fibronectin levels did not differ significantly between individuals with or without periodontal disease .

Fibronectin concentration in stimulated whole saliva, unstimulated whole saliva and GCF was not affected by treatment in a group of 10 subjects with gingivitis (Tynelius-Bratthall1988).


Thus, fibronectin levels in saliva do not differentiate between periodontal health and disease.


Blankenvoorde et al. (1997) analyzed cystatin activity in GCF and saliva of 9 periodontitis patients.

The mean cystatin concentration was lower in GCF than in saliva.

While cystatin C, S and SN were present in saliva, they could not be detected in any of the GCF samples, where cystatin A was present.

It was concluded that GCF is not a major contributor of cystatin C, S, or SN to saliva


Henskens et al. (1996) evaluated the change in concentration and activity of salivary cystatins in whole and parotid saliva from 20 periodontitis patients undergoing treatment.

After periodontal treatment, total cystatin and cystatin C concentration decreased to control levels.

The changes occurred in whole saliva but not in parotid saliva.

These results suggest that salivary glands other than the parotid gland are responsible for cystatin activity in saliva.


Henskens et al. (1996) demonstrated that levels of total protein and cystatin activity, as well as the levels of glandular-derived amylase and cystatin C, were significantly higher in whole and parotid saliva of subjects with periodontitis versus healthy controls.

The authors concluded that the salivary glands may respond to periodontitis by enhanced synthesis of some acinar proteins


In contrast, no significant differences in the levels and activity of salivary comparing periodontally healthy and diseased individuals (Aguirre et al. 1992).

These findings suggest that salivary levels of cystatins may not provide a reliable measure of periodontal disease status.


Levels of platelet activating factor (PAF), a potent phospholipid mediator of inflammation, were studied in whole saliva collected from 69 subjects (Garito et al. 1995).

A significant positive correlation was observed between the level of PAF in saliva and measures of periodontal inflammation, i.e., the % of sites with probing depths greater than 4 mm, the number of bleeding sites, and the number of histologically identified PMNs in saliva.


Rasch et al. (1995) conducted a longitudinal evaluation of the effect of periodontal therapy (oral hygiene instruction, prophylaxis and Sc/ Rp) on salivary PAF levels in 15 chronic AP patients.

A reduction in pre-treatment levels of salivary PAF was observed in response to supra gingival plaque control. These levels declined further following Sc/Rp.

The authors stated that PAF might participate in inflammatory events during periodontal tissue injury and disease.


Epidermal growth factor (EGF) is involved in oral wound healing and functions with hormone-like properties to stimulate epithelial cells.

In humans, the parotid gland is the major source of EGF (Thesleff et al. 1988).

Oxford et al. (1998) found a transient increase in salivary EGF levels in response to periodontal surgery


In a study by Hormia et al. (1993), higher EGF secretion rates in unstimulated and stimulated saliva were observed in 17 JP patients as compared with healthy age and gender matched controls.


Vascular endothelial growth factor (VEGF), also known as vascular permeability factor or vasculotropin, is a multifunctional angiogenic cytokine important in inflammation and wound healing.

Higher levels of VEGF were detected in whole saliva from periodontitis patients, in comparison to whole saliva from healthy controls. Taichman et al. 1998

However, VEGF was present in all saliva samples (Booth et al. 1998).


Several studies have examined the levels of free amino acids in saliva in relation to periodontal status

It appears that in some patients, elevated levels of certain amino acids, especially proline, may be detected Syrjanen et al. 1984.

These amino acids probably appear in whole saliva as a result of bacterial metabolism or degradation of salivary proteins rich in proline.


In another study by the same investigators (Syrjanen et al. 1990) no differences in amino acid concentrations in saliva were found between patients with progressive periodontitis and controls.

The authors concluded that levels of amino acids in oral fluids (including GCF) has no diagnostic significance for periodontal disease.


Epithelial keratins

To study epithelial cell function in periodontal disease and periodontal diagnosis, specific keratin antigens in saliva may be evaluated.

It has been suggested that phenotypic markers for junctional and oral sulcular epithelia might eventually be used as indicators of periodontal disease.

However there are no studies that demonstrate an association between number or type of epithelial cells or specific types of keratins in saliva and progression of periodontitis.


GCF keratin concentration may serve as a marker of gingival damage.

Considering the various types of immunologically- identified keratins, further studies may be warranted.


Inflammatory cells

The majority of salivary leukocytes enter the oral cavity via the gingival crevice (Schiott & Loe 1970).

Studies in the late 1960’s and the early 1970’s examined the presence of leukocytes (orogranulocytes) in saliva.

Klinkhammer et al. (1968) standardized collection and counting of leukocytes in saliva and developed the orogranulocytic migratory rate (OMR).


The OMR was found to be correlated with gingival index (Klinkhammer & Zimmerman 1969).

In an experimental gingivitis model, the number of granulocytes in saliva increased before the appearance of clinical gingivitis (Friedman & Klinkhammer 1971, Skougaard et al. 1969).


In a study by Raeste et al. (1978), the OMR was determined with sequentional mouthrinse sampling in periodontitis patients and controls.

The results indicated that the OMR reflects the presence of oral inflammation, and the authors suggested that this measure can be used as a laboratory test


However conflicting results were reported by Cox et al. (1974).

In that study, no significant correlation was found between the number of oral leukocytes and the degree of gingival inflammation.


Salivary ions

Calcium(Ca)is the ion that has been most Intensely studied as a potential marker for periodontal disease in saliva.

A high concentration of salivary Ca was correlated with good dental health in young adults, but no relationship was detected with periodontal bone loss as measured from dental radiographs (Sewon & Makela 1990).


In another study (Sewon et al. 1990), salivary Ca, and the saliva Ca to phosphate ratio were higher in periodontitis affected subjects

No differences between groups were found for flow rate and buffering capacity of saliva.

Another study from the same investigators examined differences in salivary calcium levels in a group of 20 periodontitis patients in comparison to a group of 15 periodontally healthy subjects (Sewon et al. 1995).


A higher concentration of Ca was detected in whole stimulated saliva from the periodontitis patients.

The authors concluded that an elevated Ca concentration in saliva was characteristic of patients with periodontitis.

Considering the distribution of Ca, this ion appear to hold only limited promise as a marker for periodontal disease.


Serum markers in saliva withpotential importance for periodontal

disease: cortisol Recent studies have suggested that emotional stress is

a risk factor for periodontitis (Breivik et al. 1996, Genco 1996, Linden et al. 1996, Axtelius et al. 1998).

One mechanism proposed to account for the relationship is that elevated serum cortisol levels associated with emotional stress exert a strong inhibitory effect on the inflammatory process and immune response (Chrousos & Gold 1992, Johnson et al. 1992, Fantuzzi & Ghezzi 1993


Recently, salivary cortisol levels were used to evaluate the role of emotional stress in periodontal disease.

Higher salivary cortisol levels were detected in individuals exhibiting severe periodontitis, a high level of financial strain, and high emotion-focused coping, as compared to individuals with little or no periodontal disease, low financial strain, and low levels of emotion-focused coping (Genco et al. 1998).


While it appears that emotional stress, as reflected by salivary cortisol levels, is a risk factor for periodontal disease, attempts to diagnose periodontal disease severity or activity based on salivary cortisol levels are premature.

It can be argued that in addition to changes in the host response, stress also leads to behavioral changes (i.e., smoking, poor oral hygiene and poor compliance) which could also have a significant effect on the periodontium


Nitric oxide

There is evidence that NOS-II production by resident inflammatory cells is increased in periodontitis (Kendall HK)

Increase in NOS-II production causes increases in production of nitric oxide.

In a study carried out by Dr.Supriya Koshti nitric oxide increases in patients with periodontitis with stress.

NO can inhibit collagen synthesis inducing MMP activity


In contrast Aleksic et al showed that NO in saliva of patients affected with periodontitis was lower than healthy controls.

This was in agreement with Kankanian 1996 who showed that PMNs isolated from periodontal pockets were found to have a suppressive effect in the production of NO than PMNs from venous blood.


Bacteria

It has been suggested that microorganisms in dental plaque can survive in saliva, and can utilize salivary components as a substrate.

It was shown that saliva could serve as a growth medium for oral Streptococus species and A. viscous (De Jong et al. 1984).

Bowden (1997) suggested that the number of bacterial cells for a given species in unstimulated saliva may indicate whether that microorganism is actively growing in plaque.


In a study by De Jong et al. (1986), micro-organisms from supragingival plaque were grown on saliva agar. When supragingival plaque was plated on saliva and blood agar plates, the composition of the microflora isolated from the plates were similar.

The authors concluded that the supragingival microflora could utilize saliva as a complete nutrient source.


Asikainen et al. (1991) compared the recovery of A. actinomycetemcomitans from subgingival sites, the dorsum of the tongue and saliva.

When A. actinomycetemcomitans was recovered from subgingival sites it was also found in 69.9% and 35.9% of the samples of stimulated and unstimulated saliva, respectively.

Detection of A. actinomycetemcomitans from saliva of subjects with healthy or diseased periodontium was equally effective


The authors stated that the recovery of this microorganism from stimulated saliva may provide a non-invasive, inexpensive and simple sampling method for detection of this bacterial species

Recently, Umeda et al. (1998) examined the presence of periodontopathic bacteria in whole saliva in relation to occurrence of the microorganisms in subgingival plaque.


Using polymerase chain reaction, a fair agreement was found between the presence of P. gingivalis, Prevotella intermedia and T. denticola in whole saliva and in periodontal pocket samples.

These 3 micro-organisms, in addition to Prevotella nigrescens, were detected more often in saliva than in the subgingival samples.


The effect of plaque accumulation on the salivary counts of some dental plaque microorganisms was examined in 20 subjects who refrained from oral hygiene for 7 days (Schaeken et al. 1987).

The large increase in the number of bacteria on the teeth was reflected by an increase in salivary counts of Actinomyces species.

A highly significant correlation was found between S. mutans level in dental plaque and the salivary level of this microorganism


A study of 60 children aged 5–9 years, isolation, frequency and numbers of Mycoplasma species in saliva were consistently related to gingivitis scores, which supports an association of Mycoplasmas and gingivitis in children (Holt et al. 1996).

Salivary levels of periodontal pathogens were found to vary with periodontal status and as a result of treatment


Salivary levels of A.a, P. gingivalis, P. intermedia, Campylobacter rectus, and Peptostreptococus micros were determined by bacterial culture and related to clinical periodontal status in 40 subjects with varying degrees of periodontitis (Von Troil-Linden et al. 1995).

The salivary levels of the periodontal pathogens reflected the periodontal status of the patient.


Furthermore, in 10 patients with advanced periodontitis that received mechanical debridment and adjunctive systemic metronidazole, periodontal treatment eradicated or significantly reduced the levels of periodontal pathogens in saliva.

No data were provided on the relationship between the salivary bacterial count and the subgingival levels of bacteria.


Similarly, in a study of 15 patients with moderate to severe periodontitis, a decrease in the number of patients harbouring A. actinomycetemcomitans and

P. gingivalis in saliva was noted after Sc/Rp and surgery (Danser et al. 1996).

An oral microbial rinse test (Oratest) was described by Rosenberg et al. (1989).

In this study Oratest was found to be a simple method for estimating oral microbial levels. In a companion study (Tal & Rosenberg 1990),


Oratest results were correlated with plaque index and gingival index scores, and the authors stated that this test provides a reliable estimate of gingival inflammation.


Volatiles

Volatile sulphur compounds, primarily hydrogen sulfide and methylmercaptan, are associated with oral malodor (Rosenberg et al)

Salivary volatiles have been suggested as possible diagnostic markers and contributory factors in periodontal disease.

For example, pyridine and picolines were found only in subjects with moderate to severe peroidontitis (Kostelc et al. 1980, Kostelc et al. 1981).


Furthermore, saliva seems to be a useful medium to evaluate oral malodor.

A significant association between the BANA scores from saliva and oral malodor was found (Kozlovsky et al. 1994).

However, no specific association between levels of volatiles and periodontal status has been reported.


CLINICAL SIGNIFICANCE

Down’s syndrome : Greater collagenase activity that are derived from PMNs or

cytokine-activated fibroblasts are in part responsible for the early periodontal tissue and alveolar destruction

-- Halinen et al


Papillon-Lefevre syndrome:

Salivary secretion, both stimulated and unstimulated is reduced by 50% in patients with Papillon-Leferve syndrome.

There is decrease in the amount of peroxidase activity in saliva of patients suffering from Papillon-Leferve syndrome


Diabetes mellitus :

There is increase in the amount of MMP-8 MMP-9 in saliva of patients with type II diabetes and these are related to advanced periodontitis seen in these patients

-- Colin et al

There is increase in the glucose level which is taken up by plaque bacteria, and hence promote plaque formation.

There increase in the amount of myeloperoxidase activity in saliva of patients with type I diabetes mellitus


HIV infection:

Increased activity of interstitial collagenase in saliva of patients that are HIV+ve.

Also there is increase in the amount of fibroblast-type matrix or MMP-1, stromelysin-1 (MMP-3) and neutrophil collagenases (MMP-8)

There is also increased amount of myeloperoxidase activity --Mellanen et al


Smoking:There is decrease in the amount of proteolytic enzymes

and MMP-8 levels in saliva of patients who smoke.

There is also decrease in the amount of elastase level in saliva of patients who smoke.

Hence it was suggested that care must be taken while interpreting results suggesting that the levels of elastase, proteolytic enzymes and MMP-8 might be diagnostic markers for periodontal disease activity.


Also there is decrease in the amount of cystatins in patients who smoke and decrease output of cystatin C during inflammation.


Agranulocytosis:

There is increased salivation in patients suffering from agranulocytosis

Oral contraceptives: There is decrease in the concentration of proteins, sialic

acid, hydrogen ions and total electrolytes.Increased salivary flow --- Ericson et alDecreased salivary flow -- El-Ashiry et al


Radiotherapy:

If the dose is delivered to the salivary glands then there might be xerostomia.

Parotid gland is most radiosensitive.

Saliva may become extremely viscous or nonexistent depending on the dose.


Drugs:

Increase in salivary flow :

AcetylcholineMethacholineCarbacholBethanecholMuscarinePilocarpineArecoline


Decrease in salivary flow:AntidepressantsAntihistaminics AntihypertensivesOxyphenoniumClidiniumAtropineIsopropamidePropantheline


Xerostomia Decrease in the flow of saliva or complete absence of

saliva is termed as xerostomia.

It may result from a variety of factors like sialolithiasis, sarcoidosis, Sjogren’s syndrome, Mikulicz;s disease, irradiation, surgical removal of salivary gland, pregnancy and old age.

Xerostomia results in increased caries and periodontal disease; oral mucosa is constantly irritated and sore; food is difficult to chew and swallow; and taste acuity is impaired; speech is altered


Saliva substitute:

They are intended to match the chemical and physical traits of saliva.

They are used to relieve symptoms of dry mouth.

They usually contain salt ions, flavoring agent, paraben (preservative), cellulose derivative or animal musins and fluoride.

ADA approval has been granted to products like saliva substitute and salivart

They are available as spray bottle, rinse, or oral swab stickswww.indiandentalacademy.com

In addition, products such as dry mouth toothpaste and moisturizing gels are also available for treatment of dry mouth.


ReferencesClinical periodontology-------- CaranzaText book of physiology ------- ChaudharyHuman physiology ------- Chatterjee Oral histology -------- TencateContemporary periodontics--- GencoOutline of periodontics --Eley and Manson Oral diseases------- 2002;8:117-129PNAC1986;83:6103-6106Periodontology2000,34,2004:57-83JCP 2002;29:189-194JCP2004;31:515-521Essentials of medical pharmacology ---- Tripathi


JCP 1996;23:1068-1072JCP 2001;28:979-984


JCP 2002;29:189-194JCP2004;31:515-521Essentials of medical pharmacology ---- Tripathi


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