Comparison of resin-dentine interface in primary and permanent teeth for three different durations of dentine etching.

Hybridization of dentine is identified as a basic bonding mechanism between resin and dentine, hence studying the micro morphology of hybrid layer may explain lower bond strength that has been observed in primary teeth. The aim of the present study was to compare the thickness and micromorphology of Hybrid layer formed in primary and permanent teeth for 3 different durations of dentine etching time (5, 10 and 15 sec) with 10% phosphoric acid as etchant. Thickness and micromorphology of hybrid layer was observed on SEM photographs obtained at 750X. Results indicated that primary teeth presented with a significantly thicker hybrid layer compared to permanent teeth at 10 sec (P<0.05) and 15 sec (P<0.01) of dentine etching. It was concluded that owing to the high reactivity of primary teeth to etchants, the etchants be applied for shorter period on primary dentine compared to permanent dentine for better performance of composite restoration in primary dentition.