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Etiology of Dental Caries
上海交通大学医学院附属第九人民医院牙体牙髓病科
黄正蔚
九院牙体牙髓病科 黄正蔚
Etiology is the study of causation. Derived from the Greek αἰτιολογία "giving a reason for"
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
What is this disease?
Color form Texture
九院牙体牙髓病科 黄正蔚
To find the causes …
九院牙体牙髓病科 黄正蔚
Cause of dental caries?
九院牙体牙髓病科 黄正蔚
龋 = 齿 + 禹 ( 虫 )
虫
齿
九院牙体牙髓病科 黄正蔚
Where are those worms
?
九院牙体牙髓病科 黄正蔚
Other explanations ?
Might erosion be one cause?
九院牙体牙髓病科 黄正蔚
Where is the acid ?
九院牙体牙髓病科 黄正蔚
Anton van Leeuwenhook
17th Century
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
Louis Pasteur
九院牙体牙髓病科 黄正蔚
chemico-parasitic hypothesis
—— WD. Miller(1890)
化学细菌学说
九院牙体牙髓病科 黄正蔚
dietary carbohydrates
acid production
calcium phosphate
caries
oral bacteria
solubilize
九院牙体牙髓病科 黄正蔚
SugarBacteria
from plaque Acid
Acid Healthy Tooth Decay
九院牙体牙髓病科 黄正蔚
teeth + bread/carbohydrates + saliva demineralization
Miller’s experiments :
teeth + meat/lipids + saliva non-demineralization
teeth + bread + boiled saliva non-demineralization
脱矿不脱矿
九院牙体牙髓病科 黄正蔚
1. No bacteria no caries
germfree rats Sound teeth
Evidences for caries as an infectious disease
Bacteria seperated from caries inoculated ?
九院牙体牙髓病科 黄正蔚
Streptococci seperated from caries lesion
inoculated
caries
2. Caries developed with bacteria inoculated
Evidences for caries as an infectious disease
九院牙体牙髓病科 黄正蔚
3. Antibiotics inhibited caries
Penicillin
caries
Evidences for caries as an infectious disease
McClure & Hewitt 1946
九院牙体牙髓病科 黄正蔚
Evidences for caries as an infectious disease
4. Bacteria found in all caries specimens
Caries = lesion infected with bacteria microscopically
九院牙体牙髓病科 黄正蔚
Dentinal tubules
Liquefaction focus
九院牙体牙髓病科 黄正蔚infected affected
Carious human molar
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
Conclusion
dental caries may be caused by members of the commensal oral microflora
九院牙体牙髓病科 黄正蔚
But …
Koch’s principles郭霍原则
For any microbe to be considered responsible for a given condition
九院牙体牙髓病科 黄正蔚
Koch’s postulates
The microbe should be found in all cases
九院牙体牙髓病科 黄正蔚
Koch’s postulates
The microbe should be grown on artificial media
九院牙体牙髓病科 黄正蔚
Koch’s postulates
A pure subculture should produce the disease
九院牙体牙髓病科 黄正蔚
And…
A high antibody titre to the microbe should be detected
九院牙体牙髓病科 黄正蔚
What’s then?
No single microbe has been found which completely satisfies
Koch’s postulates for caries
九院牙体牙髓病科 黄正蔚
Hypothesis on caries
ecological plaque hypothesis
Caries is a result of a shift in the balance of the resident microflora
生态菌斑学说
九院牙体牙髓病科 黄正蔚
Reevaluation of the microbial aetiology of dental caries
Fermentable sugar
AcidDe-
mineralizationLow pH
S. oralisS. sanguis
Neutral pH
S. mutansLactobacilli
Re-mineralization
Enviromental Change
Ecological Change
九院牙体牙髓病科 黄正蔚
Stephan curve
九院牙体牙髓病科 黄正蔚
dental caries multifactorial disease
九院牙体牙髓病科 黄正蔚
Introduction
“Plaque-Host-Substrate” theory
Host
九院牙体牙髓病科 黄正蔚
Factor 1 Microbiota not only Bacteria
九院牙体牙髓病科 黄正蔚
Definitions
Dental plaque (菌斑 ) Materia alba (软垢 ) Pellicle (获得性膜
) Calculus (牙结石
)
九院牙体牙髓病科 黄正蔚
Dental plaque
Dental plaque is the soft, nonmineralized bacterial deposit which forms on teeth and dental protheses that are not adequately cleaned.
------ LÖe 1965
九院牙体牙髓病科 黄正蔚
Dental plaque
Microscopically, plaque is simply confluent colonies of microorganisms connected by a matrix consisting predominantly of bacterial and salivary polymers.
九院牙体牙髓病科 黄正蔚
What is dental plaque…
Bacteria deposit On hard surfaces Bacteria + matrix
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
erythrosin stained
九院牙体牙髓病科 黄正蔚
Materia alba
bacterial aggregations, leucocytes and desquamated oral epithelial cells accumulating at the surface of plaque and teeth, but lacking the regular internal structure observed in dental plaque.
九院牙体牙髓病科 黄正蔚
Differences betweenmateria alba and plaque
Bacteria composition Internal structure Adherence strength
九院牙体牙髓病科 黄正蔚
Pellicle
an organic film derived mainly from the saliva and deposited on the tooth surface.
九院牙体牙髓病科 黄正蔚
Calculus
calcified dental plaque, it is always covered with a superficial layer of noncalcified plaque.
九院牙体牙髓病科 黄正蔚
Chemical composition of dental plaque (biofilm)
Dental plaque
(biofilm)
microorganisms
extracellular matrix
> 2X10 per gram per wet weight11
九院牙体牙髓病科 黄正蔚
Function of extracellular matrix
carbohydrate reserve framework of the biofilm inflammation-inducing, toxic substances
九院牙体牙髓病科 黄正蔚
Chemical composition of dental plaque (biofilm)
Dental plaque
(biofilm)
microorganisms
extracellular matrix
Inorganic content
Organic content
Protein 45%
Carbohydrate 15%
Lipid 12%
(Ca, P)
九院牙体牙髓病科 黄正蔚
Formation of dental plaque
九院牙体牙髓病科 黄正蔚
Formation of dental plaque
1 hr 30 d
九院牙体牙髓病科 黄正蔚
Influence factors
Diet Age Salivary factors Oral hygiene Tooth alignment Systemic disease Host factors
九院牙体牙髓病科 黄正蔚
Acquired enamel pellicle
Initial colonization
九院牙体牙髓病科 黄正蔚
Micro-colonies
九院牙体牙髓病科 黄正蔚
Microcolonies coalescing
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
Filamentousbacteria
九院牙体牙髓病科 黄正蔚
“corn-cob” associations
九院牙体牙髓病科 黄正蔚
Plaque formation
Acquired enamel pellicle formation Initial adherence and subcequent
proliferation Further aggregation
九院牙体牙髓病科 黄正蔚
Formation Mechanisms
E N A M E L
Irreversible adhesion
Co-aggregation
Reversible adhesion
九院牙体牙髓病科 黄正蔚
Formation Mechanisms
E N A M E L
Plaque formation Detachment
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
Remember…
Attachment, growth, removal and reattachment of bacteria is a continuous and dynamic process
Dental plaque will undergo continuous reorganization
九院牙体牙髓病科 黄正蔚
Biofilm (生物膜 )
九院牙体牙髓病科 黄正蔚
Bacteria living in planktonic (free swimming)
or in biofilm (dental plaque)?
九院牙体牙髓病科 黄正蔚
Batch culture Biofilm
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
九院牙体牙髓病科 黄正蔚
definition
Surface-associated bacterial community-forming microcolonies surrounded by a matrix of exopolymers
九院牙体牙髓病科 黄正蔚
Dental plaque Biofilm ?
九院牙体牙髓病科 黄正蔚
Biofilm communities
Sum of constitutive populations
Biofilm cellsAttached planktonic (liquid phase) cells
Why study biofilm?
1 + 1 2
九院牙体牙髓病科 黄正蔚
Researches revealed …
cells growing as biofilm have unique properties, some of which have great clinical significance
General propertiesProtection from host defense and predatorsProtection from desiccation Protection from antimicrobial agents Surface-associated phenotype Slow growth rate Poor penetration Inactivation/neutralizationNovel gene expression and phenotypePersistence in flowing systemsSpatial and environmental heterogeneitySpatial organization facilitating metabolic interactionsElevated concentration of nutrients
九院牙体牙髓病科 黄正蔚
Factor 2 Host
九院牙体牙髓病科 黄正蔚
Tooth morphology
6
6
caries susceptibility
九院牙体牙髓病科 黄正蔚
Tooth morphology
Pits & fissures Irregularities in arch form crowding overlapping
九院牙体牙髓病科 黄正蔚
Tooth composition
Mineralization Trace elements fluoride
九院牙体牙髓病科 黄正蔚
Enamel surface is more caries-resistant than the subsurface
九院牙体牙髓病科 黄正蔚
Host factor : Saliva
九院牙体牙髓病科 黄正蔚
Effect of desalivation on incidence and extent of caries in animals
caries
九院牙体牙髓病科 黄正蔚
Decreased salivary flow and caries in humans
Xerostomia
九院牙体牙髓病科 黄正蔚
Salivary flow rate Salivary composition and caries Salivary buffers Antibacterial factors of Glandular origin
九院牙体牙髓病科 黄正蔚
Factor 3 Substrate: diet and caries
九院牙体牙髓病科 黄正蔚
Epidemiological observations
九院牙体牙髓病科 黄正蔚
Experimental caries of animals Caries
susceptibility
九院牙体牙髓病科 黄正蔚
Controlled human studies: Vipeholm
Mental institution
九院牙体牙髓病科 黄正蔚
Toffee Chocolate Caramel
九院牙体牙髓病科 黄正蔚
Factor 4 Time
九院牙体牙髓病科 黄正蔚
Thanks!