The production of secondary caries‐like lesions on cavity walls and the assessment of microleakage using an in vitro microbial caries system

Abstract

The aim of this study was to assess microleakage along restored cavity walls using a new in vitro microbial technique. Extracted human teeth containing cavities restored with a microfine posterior composite were incubated in broth inoculated with a single strain of Streptococcus mutans for 10 days, using a sequential batch culture technique. Each margin of the cavities was finished in one of three ways: butt joint and etching; butt joint and no etching, or; bevel joint and etching. The assessment of microleakage was achieved by examining sections of the teeth histologically using polarized light for the presence or absence of caries-like cavity wall lesions. Outer (surface) lesions were also examined and displayed the characteristic zones of early natural caries lesions. The cavity wall lesions were observed as a translucent zone in 31% of butt and unetched margins, 16% of butt and etched margins, and 5% of bevelled and etched margins.