Toxicity testing of inlay cements

Abstract

This investigation was designed to study the pulpal responses to inlay cements using a technique modified from the conventional methods for testing restorative materials (BSI 1980) and to study the relationship between pulpal response and microbial microleakage. Standardised Class V cavities were prepared in ferret canine teeth after ketamine/xylazine anaesthesia. A stainless steel inlay pin was cemented into each cavity with Kalzinol, Aquacem, Poly F plus and zinc phosphate cements. Animals were killed with excess sodium pentobarbitone after seven, 14, 28 and 183 days and the canine teeth removed. Poly F plus and Kalzinol caused minimal pulpal changes. Aquacem produced a slight response whereas zinc phosphate caused the greatest response. These responses were less than when the same materials were placed in cavities alone and their onset was delayed. A significant positive correlation was found between pulpal inflammation and bacterial microleakage. There was no statistically significant correlation between pulpal inflammation and residual dentine thickness nor between bacterial microleakage and residual dentine thickness. Considerable pressure was exerted when cementing the inlay pins. so this technique provides a realistic method for testing the toxicity of inlay cements.