SEMINAR ONDENTAL PLAQUE

Submitted by:Aditi Chandra MDS- 2012 Department of Conservative Dentistry and Endodontics

DEFINITIONDental plaque: Soft deposits that form the biofilm adhering to the tooth surface or other hard surfaces in the oral cavity, including removable and fixed restorations. Bowen,1976 Bacterial aggregation on the teeth or other solid oral structures. Lindhe, 2003 Dental plaque is a specific but highly variable structural entity , resulting from sequential colonization of microorganisms on the tooth surfaces, restorations and other parts of oral cavity , composed of salivary components like mucin, desquamated epithelial cells, debris and microorganisms , all embedded in extracellular gelatinous matrix. WHO, 1961

CLASSIFICATIONBy location on tooth:

supra gingival plaque sugingival plaque

Coronal marginal unattached attached Tissue tooth Epithelium

COMPOSITIONDental plaque is primarily composed of microorganisms. One gram of plaque contains approx. 2 x 1011 bacteria. It has been estimated that more than 325 different bacterial species may be found in plaque.

Previous ClassificationNew ClassificationReference

Bacteroides gingivalisPorphyromonas gingivalisShah and Collins,1988

Bacteroides endodontalisPorphyromonasendodontalisShah and Collins, 1988

Bacteroides intermediusPrevotella intermediaShah and Collins, 1990

Bacteroides melaninogenicusPrevotella melaninogenicaShah and Collins, 1990

Bacteroides denticolaPrevotella denticolaShah and Collins, 1990

Bacteroides loescheiiPrevotella loescheiiShah and Collins, 1990

Wolinella rectaCampylobacter rectusVandamme, et al., 1991

Wolinella curvaCamplyobacter curvusVandamme, et al., 1991

SELECTED BACTERIAL SPECIES FOUND IN DENTAL PLAQUE

FacultativeAnaerobic

Gram-PositiveStreptococcus mutansStreptococcus sanguisActinomyces viscosus

Gram-negativeActinobacillusactinomycetemcomitansCapnocytophypaspeciesEikenella corrodensPorphyromonas gingivalisFusobacterium nucleatumPrevotella intermediaBacteroides forsythusCampylobacter rectus

SpirochetesTreponema denticola(OtherTreponemaspecies)

Non bacterial microorganisms that are found in plaque include mycoplasma species, yeasts, protozoa, viruses. The microorganisms exist within an intercellular matrix that also contains few host cells, such as epithelial cells, macrophages and leucocytes. Intercellular matrix takes up nearly 25% of dental plaque volume. It consists of organic and inorganic materials derived from saliva, gingival crevicuar fluid and bacterial products. Organic constituents of matrix include polysaccharides, proteins, glycoproteins and lipid material. Polysaccharide of bacterial origin contains 95% dextrans and 5% levans. Dextran is adhesive and helps in bacterial colonization. Levans acts as storage of polysaccharide providing a source of fermentable carbohydrate when hydrolyzed. Proteins: albumin probably originating from gcf. Glycoproteins: important component of plaque pellicle. Lipid material: consists of debris from the membranes of disrupted bacteria, host cells and possibly food debris.Inorganic component of plaque is primarily calcium and phosphorus, with trace amounts of other minerals such as sodium, potassium, and fluoride.The source of inorganic constituents of supragingival plaque is primarily saliva, as the mineral component increases the plaque mass becomes calcified to form calculus. Inorganic component of subgingival plaque is crevicular fluid, which is a serum transudate. Calcification of subgingival plaque also results in calculus formation.The fluoride component of plaque is largely derived from external sources such as fluoridated tooth pastes and rinses. Fluoride is therapeutically to aid in remineralisation of tooth structure, prevention of demineralization of tooth structure, and inhibition of the growth of many plaque microorganisms.The intercellular matrix forms a hydrated gel in which the embedded bacteria exist and proliferate. This gel like matrix is a primary characteristic of biofilms. The matrix confers specialized properties on bacteria that exist within the biofilm, in contrast to free floating bacteria. For eg: the biofilm functions as a barrier. Substances produced by the bacteria within the biofilm are retained and essentially concentrate which fosters metabolic interactions among the different bacteria. In addition the matrix is thought to protect resident bacteria from potentially substances such as antimicrobial agents, which may be unable to diffuse through the matrix to reach the bacterial cells.

DENTAL PLAQUE AS A BIOFILMBiofilms defined as matrix enclosed bacterial populations adherent to each other and/or to surfaces or interfaces. (Costerton, 1994). Biofilm can be formed by a single bacterial species or multiple bacterial species as well as other organisms & debris. It can form on any surfaces that is wet. It can exist on any solid surfaces that is exposed to bacteria-containing fluid.Structure of biofilm:A biofilm community comprises bacterial microcolonies, an extracellular slime layer, fluid channels, and a primitive communication system. As the bacteria attach to a surface and to each other, they cluster together to form sessile, mushroom-shaped microcolonies that are attached to the surface at a narrow base. Each microcolony is a tiny, independent community containing thousands of compatible bacteria. Different microcolonies may contain different combinations of bacterial species. Bacteria in the center of a microcolony may live in a strict anaerobic environment, while other bacteria at the edges of the fluid channels may live in an aerobic environment. Thus, the biofilm structure provides a range of customized living environments (with differing pHs, nutrient availability, and oxygen concentrations) within which bacteria with different physiological needs can survive. The extracellular slime layer is a protective barrier that surrounds the mushroom shaped bacterial microcolonies. The slime layer protects the bacterial microcolonies from antibiotics, antimicrobials, and host defense mechanisms. A series of fluid channels penetrates the extracellular slime layer. These fluid channels provide nutrients and oxygen for the bacterial micro colonies and facilitate movement of bacterial metabolites, waste products, and enzymes within the biofilm structure. Each bacterial microcolony uses chemical signals to create a primitive communication system used to communicate with other bacterialmicrocolonies.

FORMATION OF DENTAL PLAQUEFormation of plaque can be divided into 3 stages:1. Formation of dental pellicle2. Initial colonization by bacteria3. Secondary colonization and plaque maturation

Formation of dental pellicle:The surfaces of oral cavity, tissue and tooth surfaces, fixed and removable restorations are coated with glycoprotein pellicle. This is derived from components of saliva, crevicular fluid and bacterial and host tissue cell products and debris. The specific components of pellicles on different surfaces vary in composition. Studies of early enamel pellicle reveal that its amino acid composition differs from saliva, indicating that the pellicle forms by selective absorption of the the environmental macromolecules.The mechanism involved in enamel pellicle formation includes electrostatic, van der walls and hydrophobic forces. The hydroxyapatite surface has a predominance of negatively charged phosphate groups that interact directly or indirectly with positively charged components of salivary and crevicular fluid macromolecules.Surface receptors on the gram positive facultative cocci and rods allow the subsequent adherence of gram negative organisms, which have a poor ability to adhere to the pellicle. Pellicle functions as a protective barrier, providing lubrication for the surfaces and preventing tissue desiccation. Initial colonization of the tooth surface by bacteriaWithin a few hours bacteria are found on the dental pellicle. The initial bacteria colonizing the pellicle coated tooth surface are predominantly gram positive facultative microorganisms such as actinomyces viscous and streptococcus sanguis. These initial colonizers adhere to the pellicle through specific molecules termed adhesions on the bacterial surface that interact with the receptors in the dental pellicle. For eg. Cells of actinimyces viscous possess fibrous protein structures called fimbrae that extend from the bacterial surface protein adhesions on the fimbrae and specifically bind to the proline rich proteins that are found in the dental pellicle, resulting in attachment of the bacterial cell to the pellicle coated tooth surface.The plaque mass then matures through the growth of attached species, as well as the colonization and growth of additional species. In this ecologic succession of the biofilm, there is a transition from the early aerobic environment characterized by gram positive facultative species to a highly oxygen deprived environment in which gram negative anaerobic microorganisms predominate. Secondary colonization and plaque maturationSecondary colonizers are the microorganisms that do not initially colonize the clean tooth surfaces, including prevotella intermedia, prevotella toescheii, capnocytophaga species, fusebacterium nucleatum, and porphyromonas gingivalis. These microorganisms adhere to cells of bacteria already in the plaque mass. Extensive lab studies have documented the ability of different species and genera of plaque microorganisms to adhere to one another, a process known as coaggregation.This process occurs primarily through the highly specific stereo chemical interaction of protein and carbohydrate molecules located on the bacterial cell surfaces, in addition to the less specific interaction resulting from hydrophobic, electrostatic and van der wall forces.The significance of coaggregation in oral colonization has been documented in animal model studies. Well characterized interactions of secondary colonizers with early colonizers include the coaggregation of f. nucleatum with s. sanguis, p.loescheii with a. viscous, capnocytophaga ochracea with a. viscous. Most studies have focused on interactions between different gram positive species and between gram positive and gram negative species. In the later stages of plaque formation, coaggregation between different gram negative species is likely to predominate. An eg of this type of interaction is the coaggregation of f.nucleatum with p. gingivalis.

GROWTH DYNAMICS OF DENTAL PLAQUEImportant changes in the plaque growth rate can be detected within the first 24 hours. During the first 2 to 8 hour, the adherent pioneering streptococci saturate the salivary pellicle binding sites and thus cover 3% to 30% of the enamel surface. Instead of the expected steady growth during the next 20 hours, a short period of rapid growth is observed. After 1 day, the term is fully deserved because organization takes place within it. Microorganisms, packed closely together, form palisade, whereas others start to develop a pleomorphism. Each crack is filled with one type of microorganisms. As the bacteria densities approaches approximately 2 to 6 million bacteria/ mm2 on the enamel surface, a marked increase in growth rate can be observed to 32 million bacteria / mm2. The thickness of the plaque increase slowly with time, increasing to 20 to 30 micrometer after 3 days.

STRUCTURAL AND PHYSIOLOGIC PROPERTIES OF DENTAL PLAQUEA high degree of specificity is found in the interactions between bacteria in dental plaque.Supragingival plaque typically demonstrates a stratified organization of the bacterial morphotepes, gram positive cocci and short rods predominate the tooth surface, whereas gram-negative rods and filaments as well as spirochetes predominate in the outer surface of the mature plaque mass. Highly specific cell to cell interactions are also evident from the corn cob structures. Corncob formations have been observed between rod shaped bacterial cells (bacterionema matruchotti or f. nucleatum) that form the inner core of the structure and coccal cells ( streptococci and p.gingivalis) that attach along the surface of the rod shaped cells.The environmental parameters of the subgingival region differs from those of supra gingival region. Morphologic and microbiologic studies of sub gingival plaque reveal distinctions between the tooth associated and tissue associated regions of subgingival plaque.The associated plaque is characterized by gram positive rods and cocci including bacteria such as streptococcus mitis, sanguis, and a. viscous, a. naselundii.The apical border of plaque mass is separated from junctional epithelium by a layer of host leukocytes and the bacteria of this tooth associated region show an increased concentration of gram ve rods.The portion of plaque adjacent to the tissue surfaces is more loosely organized and contain primarily gram ve rods and cocci as well as large numbers of filaments, flagellated rods and spirochetes. Host tissue cells (WBCs and epithelial cells) are also found. P.gingivalis, p.intermedia, c.orchracea are main organisms. Bacteria found in tissue associated plaque (p.gimgivlis) are also found in host tissues. Thus the physical proximity is important in tissue invasion.The transition from gram positive o gram negative in dental plaque is paralleled by a physiologic transition in the developing plaque. The early colonizers (streptococci and actinomyces) utilize oxygen and lower the reduction oxidation potential of the environment, which then favors the growth of anaerobic organisms. Gram positive species utilize sugar as an energy source and saliva as a carbon source. The bacteria that predominate in the mature plaque are anaerobic and use amino acids and small peptides as energy source. Many physiologic interactions among different bacteria are found in plaque. Lactate and formate by products of metabolism of streptococci and actinomyces may be utilized in the metabolism of other plaque microorganisms.The host also functions as an important source of nutrients for eg the bacterial enzymes that degrade host proteins resulting in release of ammonia which may be used by bacteria as an energy source.Haeme iron from the breakdown of host hemoglobin may be important in the metabolism of p.gingivalis. Increase in steroid hormone is associated with significant increase in the proportion of p.intermedia found in subgingival plaque.NON SPECIFIC PLAQUE HYPOTHESISThe concept that a specific bacterial species was responsible for periodontal diseases fell out of favor for several reasons. First, despite numerous attempts, a specific bacterial agent was not isolated from diseased individuals. Rather, the organisms found associated with disease were also found associated with health. Good experimental animal model systems of periodontal disease were not available to test the pathogenicity of specific microorganisms (this, in fact, remains problematic today). Further, in the mid 1900's, epidemiological studies indicated that the older an individual was, the more likely they were to have periodontal disease. This led to the concept that the bacterial plaque itself, irrespective of the specific bacteria found in plaque, was associated with disease. This concept, known as the Non-Specific Plaque Hypothesis (Loesche, 1976), held that all bacteria were equally effective in causing disease.

SPECIFIC PLAQUE HYPOTHESISOrganisms that are found as part of the "normal" bacterial flora (i.e., found in health), may function as pathogens under certain conditions. These organisms may be altered, or increase significantly in numbers relative to other non-pathogenic species, to function as pathogens. This type of bacterial pathogen is referred to as an endogenous pathogen, in contrast to an organism that is not normally found in healthy states which is termed an exogenous pathogen. Also, tremendous advances were made in the 1960's and 1970's in techniques used to culture anaerobic microorganisms (bacterial species that cannot grow in the presence of oxygen). These advances were related to the anaerobic culturing conditions as well as the nutrients required in media to grow anaerobic species, which are typically very fastidious in their nutrient requirements. The growth of anaerobic microorganisms, and examination of their properties usingin vitroandin vivomodel systems, has now led us back to the understanding that different microorganisms have varying potential to cause disease. Thus, the current concept of the processes involved in the development of periodontal diseases falls under the Specific Plaque Hypothesis (Loesche, 1976). The Specific Plaque Hypothesis states that disease results from the action of one or several specific pathogenic species and is often associated with a relative increase in the numbers of these organism found in plaque.

CLINICAL SIGNIFICANCEThe different regions of plaque are significant to different processes associated with disease of teeth and periodontium. Eg: marginal supragingival plaque is of prime importance in the development of gingivitis. Supragingival and tooth associated subgingival plaque are critical in calculus formation and root caries. Tissue associated subgingival plaque is important in the soft tissue destruction characteristic of different forms of periodontitis.

DETECTION OF PLAQUE1. Direct vision : - Thin plaque may be translucent & therefore not visible Stained plaque may be acquired e.g tobacco stained Thick plaque tooth may appear dull & dirty

2. USE OF EXPLORER : -

Tactile Examination when calcification has started it appears slightly rough, otherwise it may feel slippery due to coating of soft , slimy plaque After removal Of Plaque when no plaque is visible, an explorer can be passed over the tooth surface & when plaque is present it will adhere to explorer tip. This technique is used when evaluating plaque index.3. Use of disclosing solutions

PLAQUE CONTROLDefinition:Removal of microbial plaque and the prevention of its accumulation on the teeth and adjacent gingival surfaces. (Dorothy Perry and Maxoschmid 1996)

Classification:1. Mechanical methods2. Chemical methods

MECHANICAL PLAQUE CONTROLThe various aids used for mechanical plaque control are as follows:1. Tooth brushes Manual toothbrush Electrical toothbrush2. Interdental cleaning aids dental floss wooden tips or rubber tips Interdental brushes Proxa brushes Bottle brushes Single tufted brushes3. Aids for gingival stimulation Rubber tip stimulator Balsa wood edge

4. Others Guaze strips Pipe cleaners Water irrigation devices5. Aids for edentulous or partially edentulous patients Denture and partial clasp brushes Cleansing solutions

TOOTHBRUSHESManual toothbrushes:Historically the purpose of brushing was to provide massage, Increase resistance of the gingival tissue, Increase keratinization and Resistance to bacterial invasion.According to The American Dental Association: Brushing surface of 1-1.25 inches (25.4 to 31.8mm) long 5/16 to 3/8 inch (7.9-9.5mm) wide 2 to 4 rows of bristles 5-12 tufts per rowParts of a toothbrush: Handle: part grasped in the hand during tooth brushing. Head: the working end of the tooth brush that holds the filaments or bristles. Tufts: cluster of bristles or filaments secured into head. Brushing plane: the surface formed by the free ends of the bristles or filaments. Shank: section that connects head and handle.Toothbrush bristles: Hard and soft Natural and synthetic Multitufted and space tuftedAdvantages of nylon filaments over natural bristles Rinse clean and dry rapidly when left in open. More durable and maintain their form longer. Ends rounded and closed, repel water and debris. More resistant to accumulation of bacteria and fungi than are natural bristles.Methods of tooth brushing: Sulcular method Bass method Roll method Rolling stroke Modified Stillman Vibratory method Stillman Charter Bass Circular method Fones Vertical method Leonard Horizontal method Physiologic method Smith Scrub brush method

The Bass Method:It is the most widely accepted and most effective method for dental plaque removal, adjacent and directly beneath the gingival margin.Technique: Position the filaments up toward the root at a 45 angle to the teeth. Place the brush with the filament tips directed into the gingival sulcus. Using a vibratory stroke brush back and forth with very short strokes for the count of ten. Reposition the brush to the next group of teeth.

The modified Stillmans Method:Technique: Like the Bass Method the filaments are placed at a 45 angle to the tooth. Unlike the Bass Method the filaments are placed half in the sulcus and half on the gingiva. The same stroke is used as the Bass.

Charters method:Technique: Position the filaments toward the chewing surface of the tooth Place the sides of the filaments against the enamel and angle them at a 45 to the tooth. Vibrate the filaments gently but firmly, keeping the filaments against the tooth. Reposition on the next set of teeth.

Fones Technique:Indicated for young children who want to do their own brushing, but do not have the muscle development for the technique which requires more co-ordination.Technique: A tooth brushing technique that uses large, sweeping, scrubbing circles over occluded teeth, with the toothbrush held at right angles to the tooth surfaces. With the jaws parted, the palatal and lingual surfaces of the teeth are scrubbed in smaller circles. Occlusal surfaces of the teeth are scrubbed in an anteroposterior direction.

Electric toothbrushes:They are also known as automatic, mechanical or powered toothbrushes.In subjects not highly motivated to oral health care, as well as in those having difficulty in mastering a suitable handbrush, "the use of an electric brush with its standard movements may result in more frequent and better cleansing of the teeth".Motions: Back and forth Circular Elliptic CombinationsCleaning action by:1. Mechanical contact between the bristles and the tooth2. Low-frequency acoustic energy generates dynamic fluid movement and provides cleaning slightly away from the bristle tips.Frequency of oscillation may be around 40 Hz.They are indicated in handicapped individuals and in dental care of hospitalized patients, with limited manual dexterity. It is also beneficial for patients undergoing orthodontic treatment.

INTERDENTAL CLEANING AIDSThey are adjunct devices which are used to remove plaque from the interproximal tooth surfaces. The specific aids required for interproximal cleaning depend on various criteria such as the size of the interdental spaces, the presence of furcations, tooth alignment, and the presence of orthodontic appliances and fixed prostheses. Dental floss:They are indicated to remove plaque from interproximal surfaces with type 1 gingival embrasures.

Types of floss multifilament Bonded / non bonded Thick / thin Waxed / non waxed Technique:1. Spool method: about 18inches of floss is taken and about 4 inches is wound around the middle finger from each end. In both the hands the last 3 fingers are folded and closed and both the hands are moved apart. In this way about 2 inches long floss is held between the index fingers of both hands.2. Circular method: in this a loop or circle of the floss is made from 18 inches long piece and both the ends are tied with 3 knots. All the fingers except the thumb of both hands are placed within the loop and the floss is held by both hands having 1inch floss between the fingers of both the hands.Wooden tips:Used as an ideal substitute to dental floss in type 2 gingival embrasures. Inserted into the gingival embrasures and remove soft deposits from teeth. Also mechanically stimulate the gingiva. Use is restricted to facial aspect of anterior teeth. Interdental brushes:Best choice of plaque removal from interproximal tooth surfaces in type 2 gingival embrasures. Design is similar to that of bottle brush. Used in posterior areas of mouth. May also be used to clean furcation areas and root concavities.

ORAL IRRIGATION DEVICESMainly beneficial in removal of unattached plaque and debris. Composed of a built in pump and reservoir. When used as an adjunct to tooth brushing these devices have a beneficial effect on periodontal health by retarding plaque and calculus formation. They may also be used to carry antimicrobial agents subgingivally.

CHEMICAL PLAQUE CONTROLIdeal requisites of antiplaque agent: Should decrease plaque & gingivitis Prevent pathogenic growth Should prevent development of resistant bacteria Should be biocompatible Should not stain teeth or alter taste Should have good retentive properties Should be economicClassification:1st generation:1. Antibiotics 2. Phenols

3. Quaternary ammonium compounds.4. Sanguanarine

2nd generation:Bis-biguanides ( Chlorhexidine )

3rd generation:Delmopinol

Vehicles for delivery of chemical agents: Tooth Paste Mouth rinses Irrigative Chewing gum Varnishes Gel Lozenges

1ST GENERATION AGENTSAntibiotics:Penicillins, Tetracycline, Vancomycin, Kenamycin, Erythromycin, Niddamycin Spiromycin, and Metronidazole have been used as agents for plaque control. Mechanism of Action is both bactericidal and bacteriostatic action. Limiting factors of systemic drug therapy is that is causes hypersensitivity reactions and bactericidal resistance.Phenols Related essential oils:These include Triclosan and Listerine. Mechanism of action: Triclosan act on cytoplasmic membrane inducing leakage of cellular constituents and thereby causing bacteriolysis.Triclosan is included in tooth paste to reduce plaque formation. Used along with Zinc citrate or co-polymer Gantrez to enhance its retention within the oral cavity. Triclosan delays plaque formation. It inhibits formation of prostaglandins & leukotrienes there by reduce the chance of inflammation.Quaternary ammonium compounds:These include Benzanthonium chloride, Benzalleonium chloride and Cetylpyredinium .They are Cationic antiseptics & surface active agents and more effective against gram positive organisms than gram negative organisms.Mechanism of action: Positively charged molecule reacts with negatively charged cell membrane phosphates and thereby disrupts the bacterial cell wall structure of microorganisms.Sanguinarine:It is a benzophenanthredine alkaloid which is most effective against gram ve organisms. When used as a mouth rinse exhibits good retentive properties with dental plaque. PH is 4.5 and alcohol content of 11.5%.Metal salts:These include Zinc Salts, Tin Salts (Stannous fluoride), Sodium fluoride and Copper salts.Mechanism of action: It reduces the glycolytic activity in bacteria &delays bacterial growth.

2ND GENERATIONBisbiguanides:These include Chlorhexidine gluconate 0.2 %, Alexidine, Cationic Chlorophenyl biguanide.Suggested for oral use by Schroder in 1969. It has a pH 3.5. It is a cationic effective against gram +ve, gram-ve, fungi, yeasts & viruses. Its superior action is due to its property of sustain availability i.e. substantivity. Mechanism Action:1. Prevents pellicle formation by blocking acidic groups on salivary glycoproteins thereby reducing glycoprotein adsorption on to the tooth surface2. Prevents adsorption of bacterial cell wall on to the tooth surface3. Prevents binding of mature plaquesAntibacterial action of chlorhexidine: It shows two actions:-1. Bacteriostatic at low concentrations

Bacterial cell wall (-ve charge)

Reacts with +ve charged chlorhexidine molecule Integrity of cell membrane altered

CHX binds to inner membrane phospholipids & increase permeability

Vital elements leak out & this effect is reversible

2. Bactericidal action

Increased concentration of chlorhexidine Progressive greater damage to membrane Larger molecular weight compounds lost Coagulation and precipitation of cytoplasm Free CHX molecule enters the cell & coagulates proteins Vital cell activity ceases Cell death

Adverse effects of chlorhexidine:1. brownish staining of tooth or restorations2. loss of taste sensation3. rarely hypersensitivity to chlorhexidine has been reported4. stenosis of parotid duct has also been reported

3RD GENERATIONDelomopinol:It inhibits plaque growth and reduces gingivitis.Mechanism of action: Interfere with plaque matrix formation & also reduces bacterial adherence It causes weak binding of plaque to tooth, thus aiding in easy removal of plaque by mechanical procedures It is therefore indicated as a pre brushing mouth rinse.

CONCLUSIONMore than 500 bacterial strains have been identified in dental biofilm. Experts agree that most forms of periodontal disease are caused by specific pathogens, particularly gram-negative bacteria. The recognition that dental plaque as a biofilm helps to explain why periodontal diseases have been so difficult to prevent and to treat. Periodontal pathogens within a biofilm environment behave very differently from free-floating bacteria. The protective extracellular slime matrix makes bacteria extremely resistant to antibiotics, antimicrobial agents, and host defense mechanisms. Mechanical removal is the most effective treatment currently available for the control of dental plaque biofilms.

REFRENCES CLINICAL PERIODONTOLOGY - CARRANZA ( 10th edition) CLINICAL PERIODONTOLOGY AND IMPLANT DENTISTRY- LINDHE ESSENTIALS OF PREVENTIVE AND COMMUNITY DENTISTRY- SOBEN PETER( 3RD edition) SHAH HN, COLLINS DM: PROPOSAL FOR RECLASSIFICATION OFBACTEROIDES ASACCHAROLYTICUS, BACTEROIDES GINGIVALIS, ANDBACTEROIDES ENDODONTALISIN A NEW GENUS,PORPHYROMONAS. INTERNATIONAL JOURNAL OF SYSTEMATIC BACTERIOLOGY 1988; 38(1):128-131.