The effect of cavity wall taper on fracture resistance of teeth restored with resin composite inlays.

The effect of a range of cavity wall tapers on fracture resistance of teeth restored with an indirect composite restoration (ICR) system has been investigated, using two methods of application of the fracturing force. The fracture load data are similar in both cases, and in neither case does ANOVA suggest a statistically significant difference in performance with cavity taper. However, the mean values are lower for the 6 degrees taper specimens, and linear regression suggests a significant decrease, which is confirmed by the mode data for the bar loading condition, which indicates a greater incidence of severe fractures for the 6 degrees taper. Since technical difficulties were encountered in the construction of inlays for the 2 degrees taper preparations, the most appropriate taper of the range assessed would appear to be 4 degrees, at least when considered with regard to fracture resistance.