There are four main criteria required for caries formation: a tooth surface ([[tooth enamel|enamel]] or [[dentin]]); caries-causing [[bacteriaබැක්ටීරියා]]; fermentable [[carbohydrate]]s (such as [[sucrose]]); and time.<ref>{{cite book |author=Southam JC, Soames JV |chapter=2. Dental Caries |title=Oral pathology |publisher=Oxford Univ. Press |location=Oxford |year=1993 |pages= |isbn=0-19-262214-5 |edition=2nd}}</ref> The caries process does not have an inevitable outcome, and different individuals will be susceptible to different degrees depending on the shape of their teeth, oral hygiene habits, and the buffering capacity of their saliva. Dental caries can occur on any surface of a tooth which is exposed to the oral cavity, but not the structures which are retained within the bone.<ref>{{cite book |author=Smith B, Pickard HM, Kidd EAM |chapter=1. Why restore teeth?|title=Pickard's manual of operative dentistry |publisher=Oxford University Press |location=Oxford [Oxfordshire] |year=1990 |pages= |isbn=0-19-261808-3 |edition=6th}}</ref>
