microbiology of dental caries
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Microbiology of Dental Caries. Shanghai Jiaotong University School of Medicine Ninth People ’ s Hospital Department of Oral Medicine Z.TANG. Definition of dental caries. Caries is defined as localized destruction of the tissue of the tooth by microbial action. Dental caries. - PowerPoint PPT PresentationTRANSCRIPT
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Microbiology of Dental Caries
Shanghai Jiaotong University School of Medicine Ninth People’s Hospital Department of Oral Medicine Z.TANG
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Definition of dental caries
Caries is defined as localized destruction of the tissue of the tooth by microbial action
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Oral flora
acids
demineralization remineralizationcavity
Chronic endogenous infection
balance
enamel
dentin
pulp
Dental caries
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Aetiology
Host factors
Plaque microorganisms
Diet
Time
No microorganism no caries
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Main microorganisms associated with caries
Oral Streptococci Lactobacillus
Actinomyces Veillonella
口腔链球菌属 乳杆菌属
放线菌属 韦荣菌属
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Oral Streptococci 口腔链球菌属mutans-group变形链球菌群 salivarious-group唾液链球菌群
anginosus-group 咽峡炎链球菌群 mitis-group 轻链球菌群
变异链球菌群
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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
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S. mutans, 变形(异)链球菌 serotypes c, e, fS. sobrinus, 远缘 ( 表兄)链球菌 serotypes d, gS. cricetus, serotype aS. rattus, serotype bS. ferus serotype cS. macacae serotype c S. downei, serotype h 8 serotypes a-h
mutans-group S. mutans-group mutans streptococci
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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
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S. mutans c,e,f
Most common isolated species from dental plaque
Primary pathogen in enamel caries
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Antigen structure of mutans streptococcus
Cell wall carbohydrate antigens Lipoteichoic acid
lipoproteins Cell-wall
Cell wall-associated proteins Antigen /Ⅰ Ⅱ( antigen B or P1)
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Extracellular polysaccharides胞外多糖Plaque formation
cariogenicity
Intracellular polysacchrides胞内多糖Carbohydrate reserves
Converted to acid when dietary carbohydrates unavailable
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Why was S. mutans considered as a putative cariogenic bacterium?
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S. mutans pathogenic in caries
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)
Importance in bacteria adhensive 黏附 ,co-aggregation共聚 and colonization 定植 to tooth surface
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S. mutans
Can adhesive to the tooth surface
Strong ability to produce acid
High acid tolerance
Play an important role in caries initiated
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S. salivariusS. vestibularis
salivarius-group唾液链球菌群 唾液链球菌前庭链球菌
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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
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S. constellatusS. intermediusS. anginosus
anginosus-group咽峡炎链球菌群
中间链球菌
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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.
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S. sanguisS. gordoniiS. parasanguisS. oralisS. mitisS. crista
mitis-group
血链球菌格登(氏)链球菌口腔链球菌轻(缓症)链球菌
轻链球菌群
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S. sanguis produce extracellular soluble and insoluble glucans from sucrose
produces a protease that can cleave sIgA
Initial adhensive in biofilm formation“Pioneer bacterium”
血链球菌
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Lactobacillus characteristics
G +
Short rod or cocci rod
microaerophilic
Acidic pH(6.0)
乳杆菌属
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Lactobacillus pathogenicity
High acid tolerance
Strong ability to produce acid
Frequently isolated from deep carious lesions
Play an important role in caries progress
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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
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Actimyces
approximal sites and the gingival crevice.
associated with root surface caries
increase in numbers during gingivitis.
放线菌属
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succinic, acetic and lactic acids
General characteristics
pleomorphic in shape
Short rodsa true branching ,T,V,Y A. israelii filamentous. Some species (particularly A.
naeslundii) are heavily fimbriated,
G +
aerobic,facultative anaerobe or anaerobe ferment glucose metabolic end products
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Actimyces
A. naeslundii
内氏放线菌A. israelii
依(衣)氏放线菌A. odontolyticus
溶牙(龋齿)放线菌A. viscosus
黏性放线菌
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A. naeslundii
produce an extracellular slime a fructan from sucrose
produce a urease that may modulate pH in plaque
内氏放线菌
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Two types of fimbriae can be found on the surface of cells
cell-to-cell contact (co-aggregation) cell-to-surface interactions
A. naeslundii
Root surface caries gingivitis
内氏放线菌
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A. israelii
actinomycosis
Sulfur granules
Cervicofacial region
Deep seated infections abdomen
Uterine in woman
依(衣)氏放线菌
放线菌病
硫磺颗粒
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A. odontolyticus50% of strains form colonies with a characteristic red-brown pigment
correlated with the very earliest stages of enamel demineralization,
with the progression of small caries lesions
溶牙(龋齿)放线菌
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Veillonella韦荣菌属
G -
Diplococci and in short chain
anaerobic
characteristic
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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
Veillonella
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Immunology of dental caries
antigen bacteria
Immune cells
antibody
B cell
sIgA
stimulate
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Immunology of dental caries
Humoral immune Cell immune
sIgA in saliva
IgG IgM in serum
(predominant)
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Immunization against dental caries
antigen
Immune cells
antibody
bacteria
B cell
sIgA
Artificial antigen
Immune cell
antibody
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Artificial active immunization Artificial passive immunization自动免疫接种 被动免疫接种
Artificial antigen vaccine
Immune cells
antibody
Artificial antibody疫苗
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Artificial active immunization Anti-caries vaccines
S. Mutans whole cell Whole cell vaccines
GTFs , PAc, et al Sub-unit vaccines
Nucleic acid vaccines
(Gene vaccines)
(DNA vaccines)
gtfB, pac
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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
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Vaccines disadvantages
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
safety
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vaccines
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)
The incidence of dental caries is falling in the West and the disease can be adequately controlled using other techniques(Fluoridation)
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
Application future
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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
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Artificial passive immunization
advantages
safety
convenience
Acceptable
disadvantages
Persist time short
May be an alternative caries-preventive strategy for the future
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Microorganisms associated with root canal infections
Way of root canal infection
Salivary contamination Caries lesion
Gingival pocket blood
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Predominant microorganisms of root canal infection
Gram-negative obligate anaerobic bacilli
革兰阴性的专性厌氧杆菌Facultative anaerobes
Predominant
lesser
Aerobic bacteriaA little
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Bacteria associated with different types of root canal infection
Apical purulent inflammationPorphyromonas endodontalis
P. gingivalis Prevotella. intermedia牙髓卟啉单胞菌
牙龈卟啉单胞菌 中间普氏菌Apical portion of root canals with necrotic pulp and periapical lesions
Actinomyces,Lactobacillus, Porphyromonas, Prevotella, Peptostreptococcus, Veillonella parvula, Enterococcus faecalis, Fusobacterium nucleatum, and S. mutans
放线菌属 , 乳杆菌属 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
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Porphyromonas endodontalis 牙髓卟啉单胞菌Black pigment
Virulence factors
liposaccharides
Bacteria capsule
Enzymes: collagenase,hyaluronidase, fibrinolysin
antigens
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Microorganisms associated with clinical symptoms of root canal infection
Acute endodontic lesions Pain, swelling, open sinus tract, tenderness to percussion
Actinomyces, Porphyromonas, Prevotella, Peptostreptococcus, Veillonella parvula, Porphyromonas endodontalis, and P. gingivalis
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Asymptomatic infections P. denticola
Acute periapical abscesses in children
P. melaninogenicus, P. oralis
齿垢普氏菌
产黑色素普氏菌 口腔普氏菌Refractory periapical periodontitis
Actinomyces isrealii 依氏放线菌
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Periapical infections
Alveolar bone
Soft tissue
Orofacial infection
Streptococcus milleri,
Peptostreptococcus species,
Peptococcus species
Most commonly isolated
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Severe orofacial infections
Prevotella, Porphyromonas, and fusobacteria
Anaerobic gram-negative rods
Mild orafacial infections
gram-positive cocci and rods
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Immunopathology of pulpal disease
Pulpal and periapical tissue Bacterial antigens
Cellular response Humoral response
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Immune cells participate in pulpal disease
Neutrophils, plasma cells, T-helper lymphocytes, T-suppressor lymphocytes, B-lymphocytes, macrophages and mast cells
T cells more numerous than the B cells
T-helper and T-suppressor cells are approximately equal numbers in chronic lesions
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neutrophils
Provide one of the first lines of defensing against the bacteria by phagocytosing whole cell and their antigens
嗜中性粒细胞
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Sensitized T lymphocytes
Respond to the bacterial antigens by releasing soluble mediators or cytokines which can not only potentiate the protective host response, but can also cause tissue destruction
Sensitized B lymphocytes
Also produce some cytokines on exposure to the sensitizing antigen and evolve into plasma cells
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Mast cells
Contribute to hypersensitivity reactions by release of histamines and other active substances upon reaction of antigens with mast cell IgE
play a role in processing of antigens for the lymphocytes and in phagocytosis
Macrophages
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The elements necessary for immunopathology present in different type infection
Inflamed dental pulp
Plasma cells containing IgG, IgA, IgM,and IgE commonly occur,with 60% of the cells containing IgG
The concentrations of IgG and IgA are elevated in inflamed pulps compared normal pulps
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Periapical granulomas
Lymphocytes, plasma cells, polymorphonuclear leukocytes, mast cells and macrophages
Acute apical abscesses
Elevated serum IgE levels
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Evaluation the contribution of immunity to the pathogenesis of periapical infection
Immune response
Potentiate protective host response Cause tissue destruction
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May be postulated to play more of a destructive than a protective role in most cases
Clinical significant
Clean antigen is very important in endodontics
Include not only bacteria and their products but also denatured host tissues