Bond Strength of Resin Cements to Dentin

Purpose:  To evaluate the shear bond strength of light-cured resin cements bonded to human dentin using individual and simultaneous light-curing techniques tested at one hour and one week. Materials and Methods: Two resin cements/bonding agents [Clearfil DC BOND/Clearfil Esthetic Cement (CEC)/Kuraray America and Adper Single Bond Plus/RelyX ARC (RX)/3M ESPE] were bonded to superficial human dentin in vitro using two curing techniques following manufacturers' instructions. Individual cure was 10-sec light cure bonding agent, 20-sec light cure 0.5-mm cement, and 20-sec light cure 2.0-mm cement. Simultaneous cure was 20-sec light cure bonding agent/0.5-mm cement and 20-sec light cure 2.0-mm cement. The specimens were stored in water at 37 C for 1 hour and 1 week before testing in shear (Ultradent test) on an Instron at 1.0 mm/min. Data were analyzed by ANOVA and Fisher's PLSD test. Failure locations (A=adhesive, C=cohesive in cement) were observed. Results: Means of bond strength with standard deviations and failure locations are listed. Fisher's PLSD intervals for comparisons of bond strength between testing times and curing treatments were 2.1 and 2.1 MPa, respectively. Means with the same superscripted letters are not different statistically (p>0.05).

                                                                                                                                                Bond Strength, MPa

Treatment                                                                                         1 Hour                                                    1 Week                        

CEC (self-etch system)

  Individual Cure                                                                        23.8(4.4)[31A/69C)^b             45.8(5.5)[39A/61C)^d

  Simultaneous Cure                                                            27.2(5.9)[56A/44C)^c             43.4(2.8)[64A/36C)^e

RX (total-etch system)

  Individual Cure                                                                        24.9(6.0)[30A/70C)^ab          48.8(2.9)[21A/79C)^d

  Simultaneous Cure                                                            26.9(4.1)[06A/94C)^ac          41.6(3.6)[15A/85C)^e

Conclusions: There were no statistical differences between bond strength of the two cements when compared under the same conditions. Bond strength tested at 1 week was 55-95% higher than bond strength tested at 1 hour. Bond strength using a simultaneous cure was comparable to the separate cure of bonding agent and cement at one hour. The bond strength of the self-etch system was less affected by simultaneous cure than that of the total-etch system. Supported in part by Kuraray America.