Comparison of the resin-dentin interface in primary and permanent teeth.

The purpose of the present study was to compare primary and permanent teeth in terms of the thickness of the hybrid layer developed with two bonding systems: Syntac (multi step) and Syntac Single Component. Fourteen sound primary first molars and 14 sound permanent first bicuspids, were removed for orthodontic reasons, and divided into 4 groups: 7 primary and 7 permanent teeth were restored with Syntac adhesive resin system (multi step); and 7 primary and 7 permanent teeth were restored with Syntac Single Component adhesive resin system. Measurements of hybrid layer thickness were performed by means of SEM and two teeth in each group were evaluated on TEM for further confirmation of resin-dentin interface. The result of this study indicated that the hybrid layer was significantly thicker in primary than in permanent teeth (p < 0.05). No difference was observed in the hybrid layers produced by two dentin bonding systems (p < 0.05).