Dental plaque 1


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Dental plaque 1

  1. 1. By Dr. Nitika JainPost Graduate Student
  2. 2.  Introduction - distinct habitats of oral cavity  Plaque – definition, types.  Structure and Composition of Dental Plaque  Plaque Formation At Ultra structural Level  Formation of dental pellicle  Initial adhesion and Attachment  Colonization  Supragingival & Subgingival Plaque Formation: Clinical Aspects  Physiologic Properties of Dental Plaque  Plaque As a Bio Film  Special Bacterial Behavior In Bio films  Plaque hypothesis – specific and non – specific  Virulence factors of periodontopathogens  Future advances in periodontal microbiology12/27/2011 DENTAL PAQUE 2
  3. 3.  On the basis of physical & morphologic criteria, oral cavity can be divided in to 5 major ecosystems:1. Intraoral, supragingival, hard surfaces (teeth, implants, restorations & prosthesis)2. Periodontal/periimplant pocket (with its crevicular fluid, root cementum or implant surface, & the pocket epithelium)3. Buccal epithelium, palatal epithelium & epithelium of floor of mouth.4. Dorsum of tongue5. Tonsils12/27/2011 DENTAL PAQUE 3
  4. 4. Teeth •Non shredding surfaces •Stagnant sites; food Cheeks, Lips, Palate impaction possible •Microflora has low •Influenced by GCF & diversity saliva •Some periodontal •Streptococcus, pathogens persist by Actinomyces, Veillonella,invading buccal cells. Fusobacteria, Prevotella, •Streptococcus spp. Treponema, unculturable predominate organisms Tongue •Highly papillated surfaces •Some anaerobic sites. •Facultative & obligate anaerobes •Diverse microflora Streptococcus, Actinomyces, Rothia, Neisseria 12/27/2011 DENTAL PAQUE 4
  5. 5. Gram Gram negative positive cocci cocci rods rods12/27/2011 DENTAL PAQUE 5
  6. 6. Cocci Rods Abiotrophia Actinobaculum Enterococcus Actinomyces Gemella Alloscardovia Preptostreptococcus Bifidobacterium Streptococcus Cornybacterium Finegoldia Eubacterium Granulicatella Filifactor Lactobacillus Propionibacterium Rothia solobacterium12/27/2011 DENTAL PAQUE 6
  7. 7. Cocci Rods Anaeroglobu Aggregatibacter Mega sphaera Campylobacter Moraxella Cantonella Neisseria Capnocytophaga Veillonella Centipeda Eikenella Leptotrichia Prevotella Porphyromonas Tanerella Treponema wolinella12/27/2011 DENTAL PAQUE 7
  8. 8. Fissure Approximal •Gram positive; Gingival crevice •Gram positive & •Facultative •Gram positive & gram negative; anaerobes gram negative & facultative & 1. Streptococcus obligate obligate 2. Actinomyces anaerobes: anaerobes: 1. Streptococcus 1. Neisseria 2. Prevotella 2. Streptococcus 3. Actinomyces 3. Prevotella 4. Treponema 4. Actinomyces Tooth 5. Eubacterium 5. veillonella12/27/2011 DENTAL PAQUE 8
  9. 9. Definitions
  10. 10.  Dental plaque is defined clinically as a structured, resilient, yellow-grayish substance that adheres tenaciously to intraoral hard surfaces, including removable or fixed restorations. “Bowen WH: Nature of plaque, Oral science review 1976” Dental plaque is a general term for complex microbial community that develops on the tooth surface, embedded in a matrix of polymers of bacterial & salivary origin. “Philip D Marsh, Michael V Martin, Oral Microbiology, 5th Edition.”12/27/2011 DENTAL PAQUE 10
  11. 11.  Dental plaque can be defined as the soft deposits that form the biofilm adhering to the tooth surface or other hard surfaces in the oral cavity, including removable and fixed restorations. Carranza 9th edition12/27/2011 DENTAL PAQUE 11
  12. 12. CHANGING VIEWS OF PLAQUE Sp pathogens identified for Non sp plaque many diseases Hypothesis Biofilm Sp plaque Search begins for oral Diseases linked hypothesis pathogens in plaque to constitutional Treatment aimed defects at Causative agent 1880 1900 1930 1960 1990 2000 Biofilm Golden age of Plaque control microbiology12/27/2011 DENTAL PAQUE 12
  13. 13. Marginal plaque* Supra gingival* Sub •Tooth associated gingival* •Tissue associated12/27/2011 DENTAL PAQUE 13
  14. 14. 12/27/2011 DENTAL PAQUE 14
  15. 15.  Dental plaque must be differentiated from other tooth deposits, like materia alba and calculus. Materia Alba refers to soft accumulations of bacteria and tissue cells that lack the organized structure of dental plaque. Calculus is hard deposits that form by mineralization of dental plaque and is generally covered by a layer of un mineralised plaque. 12/27/2011 DENTAL PAQUE 15
  16. 16.  Material alba  Calculus12/27/2011 DENTAL PAQUE 16
  17. 17. Carranza 11th edition12/27/2011 DENTAL PAQUE 17
  18. 18.  Plaque can be defined as a complex microbial community, with greater than 1010 bacteria per milligram.  Socransky SS et al “The micro biota of gingival crevice area of man” JCP 25:134, 1998 In addition to the bacterial cells, plaque contains a small number of epithelial cells, leukocytes, and macrophages. The cells are contained within an extracellular matrix, which is formed from bacterial products and saliva. The extracellular matrix contains protein, polysaccharide, lipids and glycoproteins.12/27/2011 DENTAL PAQUE 18
  19. 19. Composition – organic and in - organic12/27/2011 DENTAL PAQUE 19
  20. 20. CHEMICAL COMPOSITION OF DENTAL PLAQUE 80% water 20% solids, includes cells mainly bacteria making up 35% of the dry weight and extracellular components making 65% of the dry weight. Other than bacteria, non bacterial organisms include: • Mycoplasma • Yeast • Protozoa • Viruses Host cells in Dental plaque.  Epithelial cells  Macrophages  Leukocytes12/27/2011 DENTAL PAQUE 20
  21. 21. INTERCELLULAR MATRIX OF DENTAL PLAQUEOrganic constituentsInorganic constituentsMaterial from Saliva, GCF and bacteria12/27/2011 DENTAL PAQUE 21
  22. 22. ORGANIC CONSTITUENTS Poly saccharides - dextran 95% (adhesion), levan 5%, Sialic acid and fructose Proteins - Albumin Glycoproteins - saliva Lipid materials - Membrane remnants of bacteria and host cells.12/27/2011 DENTAL PAQUE 22
  23. 23. INORGANIC CONSTITUENTSPrimarily - Calcium & PhosphateTraces - Sodium, Potassium and FluorideFluoride - From external sources likeis derived tooth paste, mouth washes12/27/2011 DENTAL PAQUE 23
  24. 24. Formation12/27/2011 DENTAL PAQUE 24
  25. 25. The formation of the pellicle on the tooth surface Initial adhesion and attachment of bacteria Colonization and plaque maturation12/27/2011 DENTAL PAQUE 25
  26. 26.  Within nanoseconds after a vigorously polishing the teeth, a thin, saliva derived layer called the acquired pellicle, covers the tooth surface.  Consists of more than 180 peptides, proteins, glyco proteins, including keratins, mucins, proline – rich proteins, and other molecules can function as adhesion sites( receptors) for bacteria.12/27/2011 DENTAL PAQUE 26
  27. 27. ULTRA STRUCTURE OF DENTAL PELLICLE Thickness - 30 - 100 nm 2 hr pellicle: Granular structures which form globules, that connect to the Hydroxyapatite surface via stalk like structures. 24 hrs Later: Globular structures get covered up by fibrillar particles : 500 - 900 nm thick 36 hrs Later: The pellicle becomes smooth, globular12/27/2011 DENTAL PAQUE 27
  28. 28.  Studies shows ( 2 hours) enamel pellicle, its amino acids composition differs from that of saliva, indicating that the pellicle forms by selective adsorption* of the environmental macromolecules. Scannapieo FA et al , “ saliva and dental pellicles’” contemporary periodontics, 1990  Mechanism involved are:  Electrostatic forces *  Van der waals *  Hydrophobic forces*12/27/2011 DENTAL PAQUE 28
  29. 29. 12/27/2011 DENTAL PAQUE 29
  30. 30. CHEMICAL COMPOSITION OF ACQUIRED PELLICLE (Mayhell & Butller 1976, Sonju 1975) 4.6% amino acids 2.7% Hexosamine 14% Total carbohydrates Lipids - in small amountsAmino acids in the pellicle Pellicle contains more hydrophobic and less neutral amino acids than whole saliva (ie more leucine, alamine, tyrosine and sereine than saliva)Hexosamines in the pellicle Glucosamine - 18%, Galactosamine -18%Carbohydrates in the pellicle Glucose - 20%, Galactose - 27% Mannose - 9% Fructose - 18%Salivary Molecules in the pellicle Acinar cell families Mucins Proline rich proteins - statherins Cystatins, Amylases Ductal & stromal products Lactoferrin & Lysozyme 12/27/2011 DENTAL PAQUE 30
  31. 31.  This concept approaches microbial adhesion to surfaces in aquatic environment as 4 stage sequence: Colonization of surface & Attachment biofilm formation Initial adhesion Transport to surface12/27/2011 DENTAL PAQUE 31
  32. 32. Clean Molecular Single Sequentialsubstratum adsorption organisms Multiplication adsorption (Phase 1) (Phase 2) (Phase 3) of organisms (Phase 4)12/27/2011 DENTAL PAQUE 32
  33. 33.  Random contacts occur through:  Brownian motion ( 40 µm/hour)*  Sedimentation of organisms*  Liquid flow  Active bacterial movement (chemotactic activity)*12/27/2011 DENTAL PAQUE 33
  34. 34.  Reversible adhesion of the bacterium and the surface  The proteins and carbohydrates that are exposed on the bacterial cell surface become important once the bacterial are in loose contact with the acquired enamel pellicle.12/27/2011 DENTAL PAQUE 34
  35. 35.  It results in initial, reversible adhesion of bacteria, initiated by interactions between bacterium & surface through long range & short range forces, including Van der Waals attractive forces & electrostatic repulsive forces.  Derjaguin, Landau, Verwey, & Overbeek (DLVO) theory have been postulated that above a separation distance of 1nm, the summation of previous two forces describes total long range interaction, also called as total Gibbs energy (GTOT).12/27/2011 DENTAL PAQUE 35
  36. 36.  The result of (GTOT=GA+GE )summation is function of a separation distance between negatively charged particle & a negatively charged surface in a medium ionic strength suspension medium.  GTOT for most bacteria consists of secondary minimum (reversible binding takes place: 5-20 nm from the surface), a positive maximum (located at <2nm away from surface), where irreversible adhesion is established.  If a particle reaches primary minimum a group of short range forces dominates adhesive interaction & determines strength of adhesion.12/27/2011 DENTAL PAQUE 36
  37. 37.  Particles in aqueous suspension can acquire charge due to preferential adsorption of ions from solution of certain groups attached to pellicle or surface.  The charge on surface is always exactly balanced by an equivalent number of counter ions; the size of this electrical double layer is inversely proportional to ionic strength of environment.  As particle approaches surface, it experiences a weak van der Waals attraction induced by fluctuating dipoles within the molecules of the two approaching surfaces. This attraction increases as particles moves closer to substratum.  A repulsive force is encountered if the surface continue to approach each other due to overlap of electrical double layers.12/27/2011 DENTAL PAQUE 37
  38. 38. Adhesins12/27/2011 DENTAL PAQUE 38
  39. 39.  A firm anchorage between bacterium and surface will be established by specific interactions ( ionic, covalent, or hydrogen bonding)12/27/2011 DENTAL PAQUE 39
  40. 40.  Adhesins can be subdivided into two major classes:  Fimbrial adhesins, including fimbriae, pili, curli and type IV pili,  Nonfimbrial adhesins, such as autotransporter, outer membrane and secreted adhesins,  Those associated with biofilm formation Periodontology 2000, Vol. 52, 2010, 12–3712/27/2011 DENTAL PAQUE 40
  41. 41.  Fimbrial adhesins of gram-negative bacteria are classified into five major classes –  Chaperone–usher (CU) pili,  Curli,  Type IV pili,  Type III secretion pili and  Type IV secretion pili – based on their biosyntheticpathway12/27/2011 DENTAL PAQUE 41
  42. 42.  Curli are thin aggregative fimbriae identified as a new type of fimbrial adhesin expressed on the outer surfaces of some Enterobacteriaceae, such as Escherichia and Salmonella spp.  Curli promote bacterial adhesion to and invasion of the host, as well as biofilm formation, and they also function as a potent promoter of host pro-inflammatory responses.12/27/2011 DENTAL PAQUE 42
  43. 43.  Pili (from Latin for hairs) and fimbriae (from Latin for threads) are thin, filamentous, proteinaceous surface appendages (hair-like organelles) that protrude from the surface of many different bacterial species and are especially prominent on gram-negative bacteria where they are anchored within the outer membrane.12/27/2011 DENTAL PAQUE 43
  44. 44.  Type IV pili are extruded across the outer membrane and form long and flexible surface appendages expressed by major human pathogens, such as  Neisseria gonorrhoeae,  Neisseria meningitidis,  Pseudomonas aeruginosa,  Vibrio cholerae,  Salmonella enterica,  Legionella pneumophila and  the enteropathogenic E. coli.  It is quite remarkable that type IV pili assembly can be reversed and retracted through the bacterial cell wall.12/27/2011 DENTAL PAQUE 44
  45. 45. Fimbriae: • Are proteinaceous hair like appendages • Composed of protein subunits called fimbrillin • Fimbriae also carry adhesins Fimbriae of oral strain are thin, flexible and 2-3nm in diameter, thus differing from larger more rigid filmbriae found on other bacteria such as eschericia coli•Fibrils are also found oral bacterialspecies e.g. S. mitis, Prevotella intermedia, Prevotella nigrescens and S. mutans. 12/27/2011 DENTAL PAQUE 45
  46. 46. •A naeslundi is one of the most imp colonizing species ontooth surfaces. Two major types of fimbriae are present Type 1:- Are associated with adhesion of A. naeslundi to salivary acidic rich protein and to statherin deposited within salivary pellicle. Type 2: Are associated with attachment to of A.naeslundi to glycosidic receptors an epithelial cells PMNs and oral streptocci •The lectinase like adhesion to these substrates is inhibited by galactose and N. acetyl galactosamine12/27/2011 DENTAL PAQUE 46
  47. 47. The best characterized fimbriae of the oral G-ve bacteriaare those of P-gingivalis 3 types are present •They are upto 3 m long and 5nm wide, the major class ofwhich is composed of fimbrillinThe fimbrillin polypeptide binds proline rich proteinsstatherin, lactoferrin, oral epithelial cells, oral streptococciFimbrae of P.g exhibit chaemotactic properties anddemonstrate cytokine induction, both of which are necessaryfor P.g to invade epithelial cells12/27/2011 DENTAL PAQUE 47
  48. 48. Bacterium Adhesin Receptor Streptococcus spp Antigen 1/11 Salivary agglutinin Streptococcus spp LTA Blood group reactive proteins Mutans streptococci Glucan binding protein Glucan Streptococcus 35 kDA lipoprotein Fibrin, pellicle parasanguinisActinomyces naelslundii Type 1 fimbriae Proline-rich proteins Porphyromonas 150 kDA protein Fibrinogen gingivalis Prevotella loescheii 70 kDA lectin Galactose Fusobacterium 42 kDA protein Coaggregation with P. nucleatum gingivalis Oral microbiology 4th edition, Philip Marsh12/27/2011 DENTAL PAQUE 48
  49. 49. Other factors that help in attachment of bacteria• Force generating movement is an important first step in biofilm formation by G-ve bacteria• Active motility due to the production of flagella or twitchingmobility due to type IV pili are thought to increase the no ofinitial interactions between bacterial cells and solid surfacesand to help overcome initial repulsive forces between bacteriaand the surface.• Cell surface proteins of staphylococcus epidermidis and Caulobacter crescentus are imp in initial attachment.•Polysaccharide adhesion of S. epidermidis12/27/2011 DENTAL PAQUE 49
  50. 50. Primary and secondary colonizers Co aggregation Test tube brush12/27/2011 DENTAL PAQUE 50
  51. 51.  Co aggregation -  cell to cell recognition of genetically distinct partner cell types12/27/2011 DENTAL PAQUE 51
  52. 52.  They provide new binding sites for adhesion by other oral bacteria.  The metabolic activity of the primary colonizers modifies the local micro environment which influences the ability of other bacteria to survive in the dental plaque biofilm.12/27/2011 DENTAL PAQUE 52
  53. 53. 12/27/2011 DENTAL PAQUE 53
  54. 54.  They do not initially colonize the clean tooth surface but adhere to bacteria already in the plaque mass.12/27/2011 DENTAL PAQUE 54
  55. 55. 12/27/2011 DENTAL PAQUE 55
  56. 56. •Primary colonization by predominantly Gram-positive facultative bacteria. Ss: Streptococcus sanguis is most dominant. Av : Actinomyces spp. are also found in 24h plaque. • Gram-positive facultative cocci and rods co-aggregate and Multiply.12/27/2011 DENTAL PAQUE 56
  57. 57. Surface receptors on the Gram-positive facultative cocci and rods allow the subsequent adherence of Gram-negative organisms, which have a poor ability to directly adhere to the pellicle. Fn: Fusobacterium nucleatum. BI: Prevotella intermedia.12/27/2011 DENTAL PAQUE 57
  58. 58. The heterogeneity increases as plaque ages and matures. As a result of ecologic changes, more Gram-negative strictly anaerobic bacteria colonize secondarily and contribute to an increased pathogenicity of the biofilm.12/27/2011 DENTAL PAQUE 58
  59. 59.  It was described by Gibbsons & Nygaard  Corncob formation - Streptococci adheres to filaments of bacterionema matruchotti or actinomyces species  Test tube brush – composed of filamentous bacteria to which gram negative rods adhere.12/27/2011 DENTAL PAQUE 59
  60. 60. • Significance of co aggregation has been highlighted (Kollenbrander 1989, 1995, 1993) in various in vitro & in vivo studies.• F.nucleatum is central to the mechanism - since this organism can co aggregate with numerous other species.• Examples  F.nucleatum-  S.sanguis  P. loescheii  A.viscous  Capnocytophaga  P.gingivalis  B.forsythus  T.denticola 12/27/2011 DENTAL PAQUE 60
  61. 61. 18 new genera from oral cavity show co aggregation-Cell to cell recognition of genetically distinct partner celltypes (Kolen brander PE et al 1993)-Through the highly specific steriochemical interaction ofprotein and carbohydrate molecules located on the bacterialcell surface.-Mediated by lectinlike adhesins and can be inhibited bylactose and other galactosides-Coaggregation concept opens new perspectives, especiallyfor the use of probiotics12/27/2011 DENTAL PAQUE 61
  62. 62. 12/27/2011 DENTAL PAQUE 62
  63. 63. CLOSELY ASSOCIATED V.parvula COMPLEXES IN THE ORAL A.odontolyticus S.mitis CAVITY S.oralis S.sanguis C.rectus P.intermedia Streptococcus sps P.nigrescens P.gingivalis P.micros E.nodatum S.gorondi, S.intermedius F.nucleatum T.forsythus T.denticola C.showae E.corrodens LATE COLONIZERS Capnocytophaga sps A.actinomycetocomitans12/27/2011 DENTAL PAQUE 63
  64. 64. Socransky SS, Haffajee et al, “micro biel complexes insubgingival plaque” JCP 14: 588, 198712/27/2011 DENTAL PAQUE 64
  65. 65. Early colonizers: Gram positive Bacteria in Bacteria like p.use oxygen and species: mature plaque: gingivalis use bylower the redox •use sugars as an use amino acids products ofpotential, which energy sources and small other bacteriathen favours •and saliva as a peptides as •Such as succinategrowth of carbon source energy sources fromanaerobic capnocytophaga •anaerobic ochraceusbacteria •asaccharolytic •Protocheme from•streptococci campylobacter•actinomyces rectus12/27/2011 DENTAL PAQUE 65
  66. 66. Bacteria degrade p. Gingivalis Prevotella host proteins to uses hemin iron intermediarelease ammonia from the proportionswhich is used by breakdown of increases with another baceria host steroid increase as a nitrogen haemoglobin. in host. source.12/27/2011 DENTAL PAQUE 66
  67. 67.  In 1990, Marsh et al developed the ecologic plaque hypothesis  According to this, both the total no. of dental plaque and the specific microbial composition of plaque may contribute to the transition from health to disease.  A change in the nutrient status of a pocket or chemical and physical changes to the habitat are thus considered the primary cause for overgrowth by pathogens12/27/2011 DENTAL PAQUE 67
  68. 68.  New treatment concepts :  Alter the local environment by reducing the crevicular flow rate, or  The site made less anaerobic by the use of redox agents12/27/2011 DENTAL PAQUE 68
  69. 69.  During 1st 24 hrs, starting from a clean tooth surface, plaque growth is negligible from clinical view point.  Following 3 days, plaque growth increases at a rapid rate, then slows down.  After 4 days, on average 30% of total tooth crown area will be covered with plaque. Plaque does not seem to increase substantially after 4th day.  There will be a shift towards anaerobic & gram negative flora, including an influx of Fusobacteria, filaments, spiral forms & spirochetes.12/27/2011 DENTAL PAQUE 69
  70. 70.  Initial plaque formation takes place along the gingival margin & from interdental space, later further extension in coronal direction can be observed.  Plaque formation can also start from grooves, cracks, perikymata, or pits  Scanning electron microscopy reveals that early colonization of enamel surface starts from surface irregularities, where bacteria escape shear forces allowing time needed to change from reversible to irreversible binding.12/27/2011 DENTAL PAQUE 70
  71. 71.  Rough intraoral surfaces accumulate & retain more plaque & calculus in terms of thickness, area & colony forming unit.  Smoothing intraoral surfaces decreases rate of plaque formation.  There seems to be threshold for surface roughness {Ra 0.2 micrometers}, above which bacterial adhesion is facilitated.12/27/2011 DENTAL PAQUE 71
  72. 72.  Early plaque formation occurs faster.1. In lower jaw, compared to upper jaw.2. In molars areas.3. On buccal tooth surfaces, compared to oral sites.4. In interdental regions compared to strict buccal or oral surface.12/27/2011 DENTAL PAQUE 72
  73. 73.  Plaque formation is more rapid on tooth surfaces facing inflamed gingival margins, than those facing healthy gingivae. Studies suggest that increase in crevicular fluid production enhances plaque formation, it favors initial adhesion & colonization of bacteria.12/27/2011 DENTAL PAQUE 73
  74. 74.  Subject’s age does not influence de novo plaque formation.  Plaque developed in older patients resulted in more severe gingival inflammation, which indicates an increased susceptibility to gingivitis with aging.12/27/2011 DENTAL PAQUE 74
  75. 75.  Early studies, using culturing techniques examined changes in subgingival microbiota during 1st week after mechanical debridement, partial reduction followed by fast regrowth to almost pre treatment levels within 7 days.  This reveals that a high proportion of treated tooth surfaces still harbored plaque & calculus after scaling, these remaining bacteria were considered primary source for subgingival recolonization.12/27/2011 DENTAL PAQUE 75
  76. 76.  Oral implants have been used as model to study impact of surface roughness on subgingival plaque formation.  Bollen CM, et al “ The influence of abutment surface roughness on plaque accumulation and peri – impalnt mucositis” clin oral implants res 7: 201;1996  Smooth abutments were found to harbor 25 times less bacteria than rough ones, with a slightly higher density for coccoid cells.  Subgingival microflora was largely dependent on remaining presence of teeth & degree of periodontitis in remaining natural teeth.12/27/2011 DENTAL PAQUE 76
  77. 77.  Following tooth eruption the isolation frequency of spirochetes & black pigmented anaerobes increases.  Increased prevalence of spirochetes & black pigmented anaerobes is found in teenagers, this is due to hormones entering gingival crevice & acting as a novel nutrient source.  Rise in P. intermedia in plaque during 2nd trimester of pregnancy has been ascribed due to elevated levels of oestradiol & progesterone which supplies napthoquinone for growth of this microorganism.12/27/2011 DENTAL PAQUE 77
  78. 78. Effects on oral microflora Direct effects Indirect effects•Cell mediated immunity wanes •Denture wearing•Changes in salivary antibodies •Medication•Hormonal changes •Cancer therapy•Altered physiology of oral mucosa •Dietary changes Oral microflora 12/27/2011 DENTAL PAQUE 78
  79. 79.  The term biofilm describes the relatively undefinable microbial community associated with a tooth surface or any other hard, non-shedding material (Wilderer & Charaklis 1989)  Biofilms have an organized structure.  They are composed of micro colonies of bacterial cells non randomly distributed in a shaped matrix or glycocalyx.  In lower plaques layers microbes are bound together in polysaccharide matrix with other organic & inorganic materials.  On top of lower layer, a loose layer appears that is often irregular in appearance; it can extend into surrounding medium.12/27/2011 DENTAL PAQUE 79
  80. 80. In a pipePlaque on the teethIn a CreekIn a membrane
  81. 81.  Resistant of bacteria to antimicrobial agents is increased in the biofilm.  Almost 1000 to 1500times more resistant to antibiotics than in their planktonic stage  Why increased resistance?????  Nutrional status  Growth rate  Temperature  pH  Prior exposure to sub – effective conc. Of antimicrobial agents.12/27/2011 DENTAL PAQUE 82
  82. 82.  Certain properties that resists diffusion like; strongly charged or chemically highly reactive agents fail to reach the deeper part of bio film because biofilm acts as an ion- exchange resin, removing such molecules from solution.  Recently “super resistant” bacteria were identified; the cells have multidrug resistant pumps that can extrude antimicrobial agents from the cell.12/27/2011 DENTAL PAQUE 83
  83. 83. Good morning12/27/2011 DENTAL PAQUE 84
  84. 84. 12/27/2011 DENTAL PAQUE 85
  85. 85. • Genetic expression is different in biofilm bacteria when compared to planktonic (free floating) bacteria.• Biofilm cells can coordinate behavior via intercellular "communication“ using biochemical signaling molecules.
  86. 86. • Involves the regulation of expression of specific genes through the accumulation of signaling compounds that mediate intercellular communication• Dependent on cell density and mediated through signaling compounds• Quorum sensing gives biofilms their distinct properties
  87. 87. Quorum sensing is involved in the regulation ofgenetic competencematingbacteriocin productionsporulationstress responsesvirulence expressionbiofilm formationbioluminescence
  88. 88. Competence is a physiological state in which bacteriadevelop a capacity to take up exogenous DNA (Dubnau,1991)It is an elaborate process involving multiple proteincomponents and sophisticated regulatory networksIt is important to ensure that a DNA pool is availablewhen the cells become competent.
  89. 89. • In S.mutans ,quorum sensing is mediated by a competence stimulating peptide (CSP)• This peptide also induces genetic competence so that the transformation frequency of biofilm grown S.mutans was 10 to 600 fold greater than for planktonic cells
  90. 90.  Intraoral transmission of bacteria from one niche to another is called translocation or cross infection.  Christersson et al. demonstrated translocation of A.a by periodontal probes in patients with localized aggressive periodontitis.12/27/2011 DENTAL PAQUE 91
  91. 91.  To reduce the chance of intraoral translocation “one stage mouth disinfection” was introduced by Leuven group in 1990  This strategy attempts to eradicate, or at least suppress periodontal pathogens in a short time not only from periodontal pocket, but also from their habitats.  Several studies illustrate benefits of one stage full mouth disinfection approach in relation to:1. Gain in attachment2. Pocket depth reduction3. Microbiologic shifts12/27/2011 DENTAL PAQUE 92
  92. 92. Non Specific Plaque Hypothesis Specific Plaque Hypothesis12/27/2011 DENTAL PAQUE 93
  93. 93.  The nonspecific and specific plaque hypotheses were delineated in 1976 by Walter Loesche  The nonspecific plaque hypothesis maintains that periodontal disease results from the "elaboration of noxious products by the entire plaque flora.  According to this thinking, when only small amounts of plaque are present, noxious products are neutralized by the host.  Similarly, large amounts of plaque would produce large amounts of noxious products, which would essentially overwhelm the hosts defenses.  Nonspecific plaque hypothesis is the concept that control of periodontal disease depends on control of the amount of plaque accumulation.  Treatment of periodontitis by debridement (nonsurgical or surgical) and oral hygiene measures focuses on the removal of plaque and its products and is founded in the nonspecific plaque hypothesis.12/27/2011 DENTAL PAQUE 94
  94. 94.  The specific plaque hypothesis states that only certain plaque is pathogenic, and its pathogenicity depends on the presence of or increase in specific microorganisms.  This concept predicts that plaque harboring specific bacterial pathogens results in periodontal disease because these organisms produce substances that mediate the destruction of host tissues.12/27/2011 DENTAL PAQUE 95
  95. 95.  ASSOCIATION: A pathogen should be found more frequently and in higher numbers in disease states than in healthy states ELIMINATION: Elimination of the pathogen should be accompanied by elimination or remission of the disease.12/27/2011 DENTAL PAQUE 96
  96. 96.  HOST RESPONSE: There should be evidence of a host response to a specific pathogen which is causing tissue damage.  VIRULENCE FACTORS: Properties of a putative pathogen that may function to damage the host tissues should be demonstrated.  ANIMAL STUDIES: The ability of a putative pathogen to function in producing disease should be demonstrated in an animal model system.12/27/2011 DENTAL PAQUE 97
  97. 97.  The two periodontal pathogens that have most thoroughly fulfilled Socranskys criteria are Actinobacillus actinomycetemcomitans in the form of periodontal disease known as Localized Juvenile periodontitis (LJP), and Porphyromonas gingivalis in the form of periodontal disease known as adult periodontitis. 12/27/2011 DENTAL PAQUE 98
  98. 98.  Association Elevated in lesions of Juvenile Periodontitis, and some lesions of Adult Periodontitis Elevated in "active" Localized Juvenile Periodontitis (LJP) lesions Detected in apical region of periodontal pocket or in tissues of LJP lesions Unusual in health or gingivitis Elimination Elimination associated with clinical resolution of disease Species found in recurrent lesions Host Response Elevated systemic and local antibody levels in Juvenile Periodontitis Virulence Factors Leukotoxin, collagenase, endotoxin, epitheliotoxin, fibroblast inhibitory factor, bone resorption- inducing factor Animal Studies Disease induced in gnotobiotic rats12/27/2011 DENTAL PAQUE 99
  99. 99.  Association Microorganism is elevated in periodontitis lesions Unusual in health or gingivitis  Elimination Suppression or elimination results in clinical resolution  Species found in recurrent lesions  Host Response Elevated systemic and local antibody in periodontitis  Virulence Factors Collagenase, trypsin-like enzyme, fibrinolysin, immunoglobulin degrading enzymes, other proteases, phospholipase A, phosphatases, endotoxin, hydrogen sulfate, ammonia, fatty acids and other factors that compromise PMN function  Animal Studies Onset of disease correlated with colonization in monkey model  Key role in mixed infections in animal models12/27/2011 DENTAL PAQUE 100
  100. 100. PERIODONTAL HEALTH 102 to 103 bacteria. Certain bacterial species have been proposed to be beneficial to the host, including S. sanguis, Veilonella parvula, and C. ochraceus(Carranza 10th) Bacteria associated with periodontal diseases are often found in the subgingival microflora at healthy sites, although they are normally present in small proportions(Rose & Maeley, 6th) Nonmotile nature. 12/27/2011 DENTAL PAQUE 101
  101. 101.  104 to 106 bacteria. Gram-negative bacteria. Compared with healthy sites, noticeable increase also occur in the numbers of motile bacteria, including cultivable and uncultivable treponemas (spirochetes). Pregnancy associated gingivitis is accompanied by dramatic increases in levels of P. intermedia, which uses the steroid as growth factors(Carranza,10th )12/27/2011 DENTAL PAQUE 102
  102. 102.  C. rectus, P. gingivalis, P. intermedia, F. nucleatum and T. forsythia were found to be elevated in the active sites(Carranza,10th ) Sites with chronic periodontitis will be populated with greater proportions of gram-negative organisms and motile bacteria. Certain gram-negative bacteria with pronounced virulence properties have been strongly implicated as etiologic agents e.g. P. gingivalis and Tannerella forsythus. 12/27/2011 DENTAL PAQUE 103
  103. 103.  Gram -ve, and anaerobic rods. The most numerous isolates are several species from the genera Eubacterium, A. naeslundii, F. nucleatum, C. rectus, and Veillonella parvula. In some populations, a strong case can be made for Aa playing a causative role in LAP, especially in cases in which patients harbor highly leukotoxic strains of the organism. However, some populations of patients with LAP do not harbor Aa, and in still others P. gingivalis may be etiologically more important.12/27/2011 DENTAL PAQUE 104
  104. 104.  The sub-gingival flora in patients with generalized aggressive peri-odontitis resembles that in other forms of periodontitis. The predominant subgingival bacteria in patients with generalized aggressive periodontitis are P. gingivalis, T. forsythis A. actinomycetemcomitans, and Campylobacter species.12/27/2011 DENTAL PAQUE 105
  105. 105.  Unusually diverse and may contain enteric rods, staphylococci, and Candida.  Persistently high levels are found of one or more of P. gingivalis, T. forsythis, S. inter-medius, P. intermedia, Peptostreptococcus micros, and Eikenella corrodens.  Persistence of Streptococcus constellatus has also been reported.12/27/2011 DENTAL PAQUE 106
  106. 106.  More than 50% of the isolated species were strict anaerobes with P. gingivalis and F. nucleatum accounting for 7-8% and 3.4%, respectively.12/27/2011 DENTAL PAQUE 107
  107. 107.  The bacteria isolated from abscesses are similar to those associated with chronic and aggressive forms of periodontitis.  An average of approximately 70% of the cultivable flora in exudates from periodontal abscesses are gram- negative and about 50% are anaerobic rods.  Periodontal abscesses revealed a high prevalence of the following putative pathogens: F. nucleatum (70.8%), P. micros (70.6%), P. intermedia (62.5%), P. gingivalis (50.0%), and T. forsythis (47.1%).  Enteric bacteria, coagulase-negative staphylococci, and Candida albicans have also been detected.12/27/2011 DENTAL PAQUE 108
  108. 108.  High proportion of anaerobic gram negative rods, motile organisms, and spirochetes).  Species such as Aa, Pg, Tf, P. micros, C. rectus, Fusobacterium, and Capnocytophaga are often isolated from failing sites.  Other species such as Pseudomonas aeruginosa, enterobacteriaceae, Candida albicans and staphylococci, are also frequently detected around implants.12/27/2011 DENTAL PAQUE 109
  109. 109.  P. micros is a Gram positive, anaerobic, small, asaccharolytic coccus. Two genotypes can be distinguished with the smooth genotype being more frequently associated with periodontitis lesions than the rough genotype (Kremer et al. 2000). P. micros was found to be in higher numbers at sites of periodontal destruction as compared with healthy sites (Papapanou et al 2000, Riggio et al 2001). It was shown that P. micros in combination with either P. intermedia or P. nigrescens could produce transmissible abscesses (Van Dalen et al 1998). Produce protease(Grenier 2006) 12/27/2011 DENTAL PAQUE 110
  110. 110.  The salmonellas spp. are Gram negative, curved, saccharolytic rods and may be recognized by their curved shape, tumbling motility and, in good preparations, by the presence of a tuft of flagella inserted in the concave side. Moore et al (1987) described six genetically and phenotypically distinct groups isolated from oral cavity and found S. noxia at a higher proportion of shallow sites (PD>4mm) in chronic periodontitis.12/27/2011 DENTAL PAQUE 111
  111. 111.  Suggested as possible periodontal pathogens due to their increased levels in disease sites. (Moore et al 1985). E. nodatum, Eubacterium brachy and Eubacterium timidum are Gram positive, strictly anaerobic, small somewhat pleomorphic rods. Some of these species elicited elevated antibody responses in subjects with destructive periodontitis. (Martin et al 1988)12/27/2011 DENTAL PAQUE 112
  112. 112.  Some of the streptococcal species are associated with and may contribute to disease progression. Milleri streptococci, Streptococcus anginosus, S. constellatus and S. intermidius might contribute to disease progression in subsets of periodontal patients. These species was found to be elevated at sites which demonstrated recent disease progression (Dzink et al 1988). 12/27/2011 DENTAL PAQUE 113
  113. 113.  Emphasis have been placed on enteric organisms, staphylococcal species as well as other unusual mouth inhabitants. Slots et al (1990)12/27/2011 DENTAL PAQUE 114
  114. 114.  Contreras & Slots 2000, Kamma et al 200112/27/2011 DENTAL PAQUE 115
  115. 115.  Viral diseases of the oral mucosa and the perioral region are often encountered in dental practice. Viruses are important ulcerogenic and tumorigenic agents of the human mouth.12/27/2011 DENTAL PAQUE 116
  116. 116.  Four major viral families are associated with the main viral oral diseases of adults, as follows:  1. The group of herpesviruses contains eight different members that all are enveloped double- stranded DNA viruses. In the oral cavity, they are related to different ulcers, tumors, and other oral pathoses.  2.Human papillomaviruses are grouped within five genera and are nonenveloped double-stranded DNA viruses. In the oral cavity, they are related to ulcers, tumors, and oral pathoses.12/27/2011 DENTAL PAQUE 117
  117. 117.  3. Picornaviruses are all nonenveloped, single- stranded RNA viruses. In the oral cavity, they are related to ulcers and different oral pathoses  4. Retroviruses are divided into seven genera of which two are human pathogens. All retroviruses are enveloped single-stranded RNA viruses. In the oral cavity, they are related to different tumors and oral pathoses.12/27/2011 DENTAL PAQUE 118
  118. 118.  Herpesviruses are capable of infecting various types of cells, including polymorphonuclear leukocytes, macrophages, and lymphocytes. The diffuse invasion of Candida fungi and other opportunistic organisms into the gingival tissue of AIDS patients has been demonstrated to be a typical virus-mediated alteration of host defense mechanisms. Shobha Prakash, Sushma Das (2006) concluded that HSV-1 and EBV are significantly associated with destructive periodontal disease including chronic and aggressive periodontitis. HSV-1 detected sites in relation to pocket depth and clinical attachment level were found to be significant indicating that it is associated with severity and progression of destructive periodontal disease.12/27/2011 DENTAL PAQUE 119
  119. 119. 12/27/2011 DENTAL PAQUE 120
  120. 120.  Hannula J, Dogan B, Slots (2001) showed geographical differences in the subgingival distribution of C. albicans serotypes and genotypes and suggested geographic clustering of C. albicans clones in Subgingival samples of Chronic Periodontitis patients. Reynaud AH (2001) found a weak correlation between yeasts in periodontal pockets.12/27/2011 DENTAL PAQUE 121
  121. 121.  At the pathogenic end of the spectrum, it is conceivable that different relationships exist between pathogens.  The presence of two pathogens at a site could have no effect or diminish the potential pathogenicity of one or other of the species.  Alternatively, pathogenicity could be enhanced either in an additive or synergistic fashion.  It is not clear whether the combinations suggested in the experimental abscess studies are pertinent to human periodontal diseases12/27/2011 DENTAL PAQUE 122
  122. 122.  Single celled organism that are distinct from the bacteria.  Methanogenic archaea produce methane gas from hydrogen gas, carbon dioxide  Isolated from patients with periodontal disease by enriching cultures with H2 and CO2.12/27/2011 DENTAL PAQUE 123
  123. 123. 1.Dental Plaque: biological significance of a biofilm and community life style P.D.Marsh – JCP- 2005 2.Oral biofilms and Calculus – text book of Clinical periodontology and Implant dentistry - Jan Lindhe, Lang and Karring – 5th Edition 3.Periodontal microbial Ecology – Socransky and Haffajee Periodontology 2000 – Volume 38 – 2005 4.Microbiology of Periodontal diseases: Genetics, Polymicrobial communities, selected pathogens and treatment. Haffajee and socransky - Peridontology 2000, Volume 42, 200612/27/2011 DENTAL PAQUE 124
  124. 124. 5.Communication among Oral Bacteria Paul E. Kolenbrander,* Roxanna N. Andersen, David S. Blehert, G. Egland,Jamie S. Foster, and Robert J. Palmer Jr. MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, Sept. 2002 6.Interspecies Interactions within Oral Microbial Communities Howard K. Kuramitsu,1† Xuesong He,2† Renate Lux,2 Maxwell H. Anderson,3 and Wenyuan Shi2* MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, Dec. 2007 7.Microbial etiology of periodontitis Tatsuji Nishihara & Takeyoshi Koseki Periodontology 2000 Vol-3612/27/2011 DENTAL PAQUE 125
  125. 125. 8.Periodontal disease at the Biofilm-Gingival interface Offenbacher et al J.P – Oct 2007 9.Impact of 16S rRNA Gene Sequence Analysis for Identification of Bacteria on Clinical Microbiology and Infectious Diseases Jill E. Clarridge III*` CLINICAL MICROBIOLOGY REVIEWS, Oct. 2004 10.Interspecies interactions within Oral Microbial Communities Howard K.Kuramitsu, Xeusong He, Renate Lux, Maxwell H.Anderson and Wenyuan Shi Microbiology and Molecular Biology Reviews, Dec. 200712/27/2011 DENTAL PAQUE 126
  126. 126. 12/27/2011 DENTAL PAQUE 127