Type and incidence of cracks in posterior teeth.
STATEMENT OF PROBLEM: The use of magnified vision in the operatory has enhanced the early diagnosis of structural defects in the dentition and in existing restorations. There is little in the literature to guide the clinician on the significance of cracks and other interruptions in the integrity of teeth. PURPOSE: This study characterized the type and incidence of cracks in posterior teeth and identified possible etiologic factors. MATERIAL AND METHODS: An observational cross-sectional survey of 51 patients from a private practice examined during an 18-month period was used to identify 4 types of cracks in posterior teeth. The study identified both patient- and tooth-level variables present in each patient examined. The data were subjected to statistical analysis to determine whether correlations existed between the variables and cracks. RESULTS: Cracks in teeth were shown to have chronicity and can be classified according to appearance. Variables such as the presence of a Class I or II restoration and the presence of excursive interferences were shown to significantly increase (P< .0001) the chances of a crack being present. Combinations of variables, such as interferences and a restoration, also increased the chance of a crack being present. CONCLUSION: Within the limitations of this study, the presence of cracks in teeth was associated with the placement of a Class I or II restoration and with the presence of excursive interferences. Age played a role in the presence of stained or symptomatic cracks, which suggests that cracks have chronicity. Although many questions remain regarding prevention, it is evident that protecting teeth from excursive interferences and parafunction may thwart premature breakdown.