Dental Caries,Ouyang Yong Associate professor Department of Endodontics and Operative Dentistry Sun Yat-sen University,岳松龄 王满恩 史俊南 刘正 樊明文,李玉晶 王嘉德 周学东 高学军 凌均棨 刘天佳,学习龋病学需要了解的人,史俊南,刘正,樊明文,李玉晶,周学东,凌均棨,吴补领,高学军,Introduction,Photos of dental caries,Photos of dental caries,Photos of dental caries,Caries is Latin for rot or rotten. Dental caries means rotten teeth. Caries is the noun which names the disease Carious is the adjective, not a caries, a carious area or an area of caries.,Dental caries can be defined as,Chronic progressive deconstructive disease of hard dental tissuesBacterial infected diseases caused by specific bacteria a reversible multifactorial process of tooth demineralization and remineralization.,Dental caries,Dental caries, a bacterial infection, may be define as a posteruptive pathological process of external origin, involving the softening of the hard dental tissue and proceeding to cavity formation. This is distinct from the dissolution of the hard dental tissues of an unerupted tooth which is not dental caries but tooth resorption.,The carious process,a pathological process of localized destruction of calcified tooth tissues by acids produced by organisms. Etiologically caries is considered a multi-factorial disease, which involves interplay between the host (saliva and teeth) micro organisms (streptococcus mutans), and the substrate (dietary carbohydrate sucrose), with the production of Lactic acid. Dental plaque (Bio-film) serves as the medium for caries development.,Basic pathological changes,demineralization of inorganic tissues of tooth Disintegration of the organic tissues of tooth involves enamel, dentin, cementum,Epidemiology of dental caries 流行病学,Prevalence rate（患病率）：is the proportion of a population affected by a disease of a condition at one point time. Incidence（发病率）：is a mesurement of the rate at which a disease progresses the increase or decrease in the number of new cases occurring in a population within the same time period,Measuring caries activity,DMF index,D the mean number of decayed teeth with untreated carious lesions M the mean number of teeth which have been extracted and are therefore missing F the mean number of filled teeth DMF(T) to denote decayed,missing, and filled teeth DMF(S) to denote decayed,missing, and filled surfaces in permanent teeth dmf(t) dmf(s) similar indices for the primary dentition,Frequency distribution of dental caries according to various tooth location,permanent dentition,Deciduous dentition,distribution of dental caries according to tooth surface,Occlusal interproximal buccal,Caries is world wide in its distribution,The prevalence of dental caries increases with the development of economy High DMF before 1970 in the industrialized countryTo decrease after 1970 in the industrialized country More prevalence in industrialized than in the third word country Caries experience tends to increase in the developing country and decline in many western countries. Caries experience is higher in urban than in rural communities in developing countries.,Prevalence of dental caries (1995)，special for 12-18Y age groupsis increased significantly （20-40%）In recent 10 years, prevalence of dental caries in primary dentition is increased significantly than the permanent,Why has caries prevalence decreased in modern population?,The is possibly attributable to The fluoridation of drinking water, use of fluoride toothpastes and improved oral health A changing pattern of sugar consumption A decrease in virulence(毒力) of the organsims,Aetiology of dental caries 龋病的病因学,The organic deposits on the enamel surface,four factors is essential for the initiation of dental caries, namely:,Micro-organism mutans streptococci Lactobacilli Actinomyces,Substrate Refined carbohydrates(精制碳水化合物) such as sucrose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,Susceptible teeth易感牙 The ingestion of fluorides during tooth mineralization leads to the formation of fluor-apatite in enamel. Its presence in enamel makes the tooth less susceptible to dental caries because it is less soluble in acid than the hydroxyapatite(羟磷灰石) which is normally present in the hard dental tissues,Time All the factors should be present for sufficiently long time for the caries process to be initiated.,Definition:,Dental plaque（牙菌斑）,Classification of Dental plaque,supragingival plaque -dental caries subgingival plaque-periodontal diseases,STRUCTURE OF DENTAL PLAQUE,Plaque on smooth surfacePlaque-dental surfaceMiddle layer- condensed microbial layer body of plaqueThe surface layer of plaque Plaque in pit and fissure,Composition of Dental plaque,bacteria which form 50-70% of dental plaque a small number of epithelial cellsLeukocytesMacrophages glycoproteins which, together with extracellular polysaccharides, form the plaque matrixmucopolysaccharides (粘多糖) such as glucans and fructans(右旋糖) Inorganic components calcium phosphorusfluorides .,