重医附一院口腔科 唐明 1.Definition Dental caries is caused by certain organism of the oral flora（菌丛）. It is an irreversible, slowly progressive decay of the hard tissues of individual teeth. the high incidence : 40-65% a multifactorial disease a chronic disease hard tissues of tooth: (enamel,cementum,dentin) an irreversible decay characterstic demineralization of apatites（磷灰石脱矿）磷灰石脱矿） decomposition of organic substance（有机物分解）（有机物分解） disintegration （崩解）崩解）of tooth structures cavitation（洞腔形成）洞腔形成） The carious process 2.Four Factors theory Four Factors Is Essential For The Initiation Of Dental Caries Namely: Cariogenic bacteria Food Host Time Cariogenic bacteria -Dental Plaque（牙菌斑）（牙菌斑） streptococcus mutans（变形链球菌） lactobacillus（乳酸杆菌） actinomyces（放线菌属） Food Refined carbohydrates(精制碳水化合物精制碳水化合物) such as sucrose蔗糖蔗糖 provide a suitable substrate on which the cariogenic micro-organisms act to produce the acids that lead to dissolution of the hard dental tissues Caries experience is influenced by the quantity, quality and especially frequency of consumption of the refined carbohydrate Tooth morphology bacterial plaque is an essential precursor of caries , sites on the tooth surface which favour palque retention and stagnation are particularly prone to decay Saliva under normal conditions, the tooth is continually bathed in saliva. It is capable of remineralizing the early carious lesion because it is supersaturated with Ca and P. when salivary buffering capacity has been lost, a low Ph environment is encouraged and persists longer Fluoride particular interest was the discovery of the association between fluoride concentration in water supplies and prevalence of dental caries in children Host Time Certain time is needed for the carious process Tetra-factor hypothesis microorganisms Host & tooth substrate time caries The four circle diagrammatically represent the parameters involved in the carious process. All four factors must be acting concurrently (overlapping of the circles) for caries to occur. Caries requires a susceptible host, a cariogenic oral flora and a suitable substrate that must be present for a sufficient length of time 3.Classification superficial caries : enamel/cementum intermediate caries : superficial dentin deep caries :dentin superficial caries Lesion inside enamel No feeling Color change intermediate caries Lesion inside superficial dentin Susceptible to cold, hot, sour, sweet Color change(brown) Cavity deep caries Dentin lesion More susceptible to cold, hot,sour,sweet Color change(brownblack) Deeper cavity superficial caries intermediate caries deep caries Other classification Acute caries Chronic caries 1. varieties for Color , form , hardness of tooth 2. There are three general areas on tooth surfaces where decay starts: 1) pits and fissures of molars and bicuspids, 2) buccal and labial surfaces near the gingival line, 3) proximal surfaces that lie in the areas between the contact point and the gum. 4.clinical characteristics 5.Diagnosis 1.mainly made by ： Clinical characteristics 2.Detection The major examination materials include - mouth mirror: look explorer/probe: exploration nipper: percussion, radiographs, etc. radiograph to distinguish caries from 6.Treatmen t (1) chemical therapy: 75% NaF , 10%AgNO3 (2) plugging- recovery of form and function: cavity preparation: resistance form, retention form cavity filling: ZOE, ZOP, silver amalgam cavity preparation filling checking once a year 7.prevention prevention pit and fissure sealing