Evaluation of regional bond strength of resin cement to endodontic surfaces

The purpose of this study was to test the feasibility of adapting a new mic rotensile testing technique to measure resin cement bond strengths to the c ervical, middle, and apical thirds of root canals. Post spaces were created in extracted human teeth, and the roots were ground flat on one side to ex pose the canal and permit ideal placement of one of two resin cements (Pana via 21 or C&B Meta-bond). After 48 h of storage, serial l-mm-thick cross-se ctions were cut to create 6-10 specimens per root. The first three specimen s were from the cervical third, the next three were from the middle third, and the last three were from the apical third of the root. Each 1 x 1 x 8 m m specimen was pulled to failure in a miniature testing machine. The result s indicated that both resin cements produced high bond strengths (12-23 MPa ), and that bond strengths to the apical third were significantly higher (p < 0.05) than to the cervical or middle third with either cement. This new method shows promise for evaluating resin bond strengths within root canals .