evaluation of the biocompatability of a resilient and a hard resins utilize mucous membrane irritation test

This study was conducted to test the biocompatibility of Coe soft resilient chemically cured resin and Triad hard visible light-cured [VLC] resin utilizing rabbit's cheek mucous membrane irritation test. Two control materials were used: Gutta percha as a negative control and polyvinyl chloride [PVC] as a positive control. Two weeks after fixation of specimens on the buccal mucosa, the surface of the tissue underlying Coe soft resilient resin appeared normal, while that underlying Triad hard VLC resin was corrugated with redness of the surrounding region. Histopathological evaluation of the rabbit's buccal mucosa underlying Coe soft showed evidence of mild irritation. However, the buccal mucosa underlying Triad hard VLC resin showed ulceration and formation of granulation tissue. The appearance of flattened epithelial cells over the granulation tissue suggested evidence of regeneration

study of the sealing ability of thermafil root canal filling material

The aim of this study was to evaluate the sealing ability of Thermafil root canal filling material as correlated with the shape of the prepared root canal walls, when instrumented with three different enlarging instruments. Fifty human central incisors were used in this study and were divided into three groups. Groups A and B, having 20 teeth in each, were prepared with square cross section K-type files and triangular cross section Flex-R files, respectively. These two groups were subdivided into two equal halves according to the mode of action used in mechanical preparation [filing or reaming action]. Group C consisted of 10 teeth prepared with triangular cross section K-type reamers using reaming action. Root canals were obturated using a standard size [50] of Thermafil with sealer. The extent of dye penetration was measured under stereomicroscope after clearing of teeth. When the results were subjected to an analysis of variance at P = 0.05, no significant difference in dye penetration existed between the three tested groups when compared as a whole. However, a significant difference existed between the subgroups prepared with different modes of action with better restriction of dye penetration in canals prepared using reaming action. Manufacturer discrepancies in Thermafil and sealer extrusion seemed to be main disadvantages