Shear bond strengths of three resin cements to dentine over 3 years in vitro

Objectives: This study was conducted to evaluate the bond durability of thr ee resin cements bonded to bovine dentine over a period of 3 years. Methods: Ten bovine dentine specimens were tested for shear bond strengths with each of the following materials: Panavia 21, BISTITE resin cement, and MASA Bond (experimental resin cement) at 1 day, 6 months, 1 and 3 years af ter cementation of a composite rod. All specimens were stressed in shear at a crosshead speed of 1 mm min(-1) until failure. The means of the bond str engths were compared statistically by two-way ANOVA and Fisher's PLSD test (P < 0.05). The mode of failure was classified after fracture of the bonds by SEM observation. Results for the mode of fracture were analyzed using th e Mann-Whitney U-test. Results: The shear bond strengths (MPa +/- SD) for different times (1 day, 6 months, 1 and 3 years) were: Panavia 21 (15.2 +/- 3.6, 9.3 +/- 3.2, 8.5 /- 2.1, 6.8 +/- 2.4), BISTITE (15.6 +/- 2.8, 11.0 +/- 1.4, 10.4 +/- 2.2, 9. 0 +/- 2.7) and MASA Bond (29.6 +/- 9.5, 17.5 +/- 4.6, 19.6 +/- 4.5, 16.1 +/ - 5.4). Panavia 21 and BISTITE strengths were significantly tower (P ( 0.05 ) at all times compared with MASA Bond. and 1day strengths for all three ma terials were significantly higher (P < 0.05) than 3 year strengths. Regardi ng the fracture modes after bond testing, there were statistical difference s between the 1 day and the 1 year results for all cements (P < 0.05). Alth ough no Panavia 21 specimen showed complete cohesive failure in the deminer alized dentine during the experiment, several BISTITE and MASA Bond specime ns showed cohesive fracture in the demineralized dentine. For BISTITE. part ially or complete demineralized dentine cohesive failures increased over ti me. Conclusions: The type of resin cement seemed to have an influence on the lo ng-term durability of bonding to dentine. (C) 2001 Elsevier Science Ltd. Al l rights reserved.