Microbiology of Dental Caries

1. Microbiology of Dental Caries Shanghai Jiaotong University School of Medicine Ninth People’s Hospital Department of Oral Medicine Z.TANG

2. Definition of dental caries Caries is defined as localized destruction of the tissue of the tooth by microbial action

3. Dental caries Chronic endogenous infection enamel Oral flora dentin acids pulp cavity demineralization remineralization balance

4. Aetiology Plaque microorganisms Host factors Diet Time No microorganism no caries

5. Main microorganisms associated with caries Lactobacillus Oral Streptococci 口腔链球菌属 乳杆菌属 Actinomyces Veillonella 放线菌属 韦荣菌属

6. Oral Streptococci口腔链球菌属 mutans-group 变形链球菌群 salivarious-group 唾液链球菌群 变异链球菌群 anginosus-group 咽峡炎链球菌群 mitis-group 轻链球菌群

7. Oral Streptococci General characteristics G＋gram stainning positive 革兰染色阳性 Spherical or oval cocci in pairs and chains Microaerophilic微需氧or facultative anaerobic兼性厌氧

8. mutans-group S. mutans-group mutans streptococci S. mutans, 变形（异）链球菌serotypes c, e, f S. sobrinus, 远缘(表兄）链球菌serotypes d, g S. cricetus, serotype a S. rattus, serotype b S. ferus serotype c S. macacae serotype c S. downei, serotype h 8 serotypes a-h

9. S. mutans history 1924 Clark originaly isolated 1960s paid attention to it S. mutans , its name derive from the fact that cells can lose their coccal morphology and often appear as short rods or as cocco-bacilli

10. S. mutans c,e,f Most common isolated species from dental plaque Primary pathogen in enamel caries

11. Antigen structure of mutans streptococcus Lipoteichoic acid Cell wall carbohydrate antigens lipoproteins Cell-wall Cell wall-associated proteins Antigen Ⅰ/Ⅱ（antigen B or P1)

12. Plaque formation Extracellular polysaccharides 胞外多糖 cariogenicity Carbohydrate reserves Intracellular polysacchrides 胞内多糖 Converted to acid when dietary carbohydrates unavailable

13. Why was S. mutans considered as a putative cariogenic bacterium?

14. S. mutans pathogenic in caries Importance in bacteria adhensive黏附 ,co-aggregation 共聚and colonization定植to tooth surface Ability to produce acid产酸能力:Produce acid at an extremely rate from pulses of fermentable carbohydrate Acid tolerance耐酸性:Grow ,survive and produce acid under low pH(4.5~5.0)

15. S. mutans Can adhesive to the tooth surface Strong ability to produce acid High acid tolerance Play an important role in caries initiated

16. salivarius-group 唾液链球菌群 S. salivarius S. vestibularis 唾液链球菌 前庭链球菌

17. S. Salivarious 唾液链球菌 colonizes mucosal surfaces, especially in the tongue produce an extracellular fructan not considered as a significant opportunistic pathogen

18. anginosus-group 咽峡炎链球菌群 S. constellatus S. intermedius S. anginosus 中间链球菌

19. S. intermedius 中间链球菌 isolated mainly from liver and brain abscess produce a protein toxin, termed intermedilysin Not make extracellular polysaccharides from sucrose.

20. mitis-group 轻链球菌群 S. sanguis S. gordonii S. parasanguis S. oralis S. mitis S. crista 血链球菌 格登（氏）链球菌 口腔链球菌 轻（缓症）链球菌

21. S. sanguis produce extracellular soluble and insoluble glucans from sucrose 血链球菌 produces a protease that can cleave sIgA “Pioneer bacterium” Initial adhensive in biofilm formation

22. Lactobacillus characteristics 乳杆菌属 G ＋ Short rod or cocci rod microaerophilic Acidic pH(6.0)

23. Lactobacillus pathogenicity Frequently isolated from deep carious lesions High acid tolerance Strong ability to produce acid Play an important role in caries progress

24. As the isolation of lactobacilli in large numbers from saliva points to the presence of carious activity, they may be used as “caries marker organisms”, 龋标志菌especially in epidemiological studies

25. Actimyces 放线菌属 approximal sites and the gingival crevice. associated with root surface caries increase in numbers during gingivitis.

26. General characteristics G＋ ferment glucose metabolic end products aerobic,facultative anaerobe or anaerobe • pleomorphic in shape • Short rods • a true branching ,T,V,Y • israelii filamentous. • Some species (particularly A. naeslundii) are heavily fimbriated, succinic, acetic and lactic acids

27. Actimyces A. naeslundii A. israelii 内氏放线菌 依（衣）氏放线菌 A. odontolyticus A. viscosus 溶牙（龋齿）放线菌 黏性放线菌

28. A. naeslundii 内氏放线菌 produce an extracellular slime a fructan from sucrose produce a urease that may modulate pH in plaque

29. A. naeslundii 内氏放线菌 Two types of fimbriae can be found on the surface of cells cell-to-cell contact (co-aggregation) cell-to-surface interactions gingivitis Root surface caries

30. A. israelii 依（衣）氏放线菌 Cervicofacial region Deep seated infections abdomen actinomycosis 放线菌病 Uterine in woman Sulfur granules 硫磺颗粒

31. A. odontolyticus 50% of strains form colonies with a characteristic red-brown pigment 溶牙（龋齿）放线菌 correlated with the very earliest stages of enamel demineralization, with the progression of small caries lesions

32. Veillonella characteristic 韦荣菌属 G－ Diplococci and in short chain anaerobic

33. Veillonella Require lactate for growth Unable to metabolize normal dietary carbohydrates Used lactate produced by other microorganisms Convert lactate into weaker acids(propionic acid) A beneficial effect on dental caries

34. Immunology of dental caries bacteria antigen stimulate B cell Immune cells sIgA antibody

35. Immunology of dental caries Humoral immune Cell immune (predominant) sIgA in saliva IgG IgM in serum

36. Immunization against dental caries Artificial antigen antigen bacteria B cell Immune cell Immune cells sIgA antibody antibody

37. Artificial active immunization Artificial passive immunization 自动免疫接种 被动免疫接种 Artificial antigen vaccine Artificial antibody 疫苗 Immune cells antibody

38. Artificial active immunization Anti-caries vaccines S. Mutans whole cell Whole cell vaccines GTFs , PAc, et al Sub-unit vaccines Nucleic acid vaccines gtfB, pac (Gene vaccines) (DNA vaccines)

39. Vaccine may produce its protective effect by Inhibition of the microbial colonization of enamel by sIgA Interference with bacterial metabolism Enhancement of phagocytic activity in the gingival crevice area due to the opsonization调理 of S. mutans with IgA or IgG antibodies

40. Vaccines disadvantages safety The antibodies which develop after immunization with most Strep. Mutans antigens tend to cross-react with heart tissue, and the possibility that heart damage could result has made human vaccine trials very difficult Weak immunogen Only tested in animal experiments

41. vaccines Application future unacceptible acceptible There are fears of possible side-effects which would be unacceptible as caries is not a life –threstening disease(coss-react with heart tissue) Developing countries with little or no organized dental services and increasing prevalence of caries Prevention of disease in special high-risk groups,e.g. mentally or physically handicapped child The incidence of dental caries is falling in the West and the disease can be adequately controlled using other techniques(Fluoridation)

42. Artificial passive immunization Heteroimmunization cow milk IgG 异种免疫 Monoclonal antibodies against Pac, GTF 单克隆抗体 Egg yolk antibody IgY 鸡卵黄抗体 Transgenic plants antibody tobacco 转基因植物抗体 Local used in oral cavity toothpaste mouth wash

43. Artificial passive immunization disadvantages advantages Persist time short safety convenience Acceptable May be an alternative caries-preventive strategy for the future

44. Microorganisms associated with root canal infections Way of root canal infection Salivary contamination Caries lesion Gingival pocket blood

45. Predominant microorganisms of root canal infection Predominant Gram-negative obligate anaerobic bacilli 革兰阴性的专性厌氧杆菌 lesser Facultative anaerobes Aerobic bacteria A little

46. Bacteria associated with different types of root canal infection Porphyromonas endodontalis Apical purulent inflammation 牙髓卟啉单胞菌 P. gingivalis Prevotella. intermedia 牙龈卟啉单胞菌 中间普氏菌 Apical portion of root canals with necrotic pulp and periapical lesions 放线菌属,乳杆菌属 Actinomyces,Lactobacillus, Porphyromonas, Prevotella, Peptostreptococcus, Veillonella parvula, Enterococcus faecalis, Fusobacterium nucleatum, and S. mutans 卟啉单胞菌属 普氏菌属 消化链球菌属,极小韦荣菌 粪肠球菌,聚核梭杆菌,变形链球菌

47. Porphyromonas endodontalis 牙髓卟啉单胞菌 Black pigment liposaccharides Bacteria capsule Virulence factors antigens Enzymes: collagenase,hyaluronidase, fibrinolysin

48. Microorganisms associated with clinical symptoms of root canal infection Pain, swelling, open sinus tract, tenderness to percussion Acute endodontic lesions Actinomyces, Porphyromonas, Prevotella, Peptostreptococcus, Veillonella parvula, Porphyromonas endodontalis, and P. gingivalis

49. Asymptomatic infections P. denticola 齿垢普氏菌 Acute periapical abscesses in children P. melaninogenicus, P. oralis 产黑色素普氏菌 口腔普氏菌 Refractory periapical periodontitis Actinomyces isrealii 依氏放线菌

50. Periapical infections Streptococcus milleri, Peptostreptococcus species, Peptococcus species Alveolar bone Soft tissue Most commonly isolated Orofacial infection