Daniele Scaminaci Russo

Translucent fiber post cementation using light- and dual- curing adhesive techniques and a self-adhesive material: Push-out test

OBJECTIVES To compare, by means of the push-out test, the interfacial strength of two dual resin cements and one light-curing cement when used in translucent fiber post cementation. METHODS Thirty-nine, endodontically treated, single canal, extracted human bicuspids were selected. Translucent fiber posts (RelyX Fiber Post) were luted into the root canal using three resinous luting systems (n=13). Dual-curing technique (DC): the specimens were treated with Excite DSC and RelyX ARC, which were light-cured simultaneously through the post for 60s. Self-adhesive dual-curing technique (SADC): the specimens were treated with RelyX Unicem, which was light-cured through the post for 60s. Light-curing technique (LC): the specimens were treated with Excite DSC and Tetric Flow, which were simultaneously light-cured through the post for 60s. The specimens were transversally sectioned into six slices in order to perform the push-out test. Data were analyzed by two-way ANOVA followed by the Tukey-Kramer test for post-hoc comparisons at alpha=0.05. RESULTS At every region, results did not show any statistical difference between the DC and LC techniques. With the LC technique bond strength values were lower at the apical region than those recorded at the coronal and middle regions. At the coronal and middle regions, bond strength values for the SADC technique were lower than those resulting when using the other two techniques. At the apical region, there was not significant difference in bond strength between the luting techniques tested. CONCLUSIONS The interfacial strength between light-curing cement and root canal is equivalent to the interfacial strength between dual-curing cement and root canal.

Double microtensile bond strength test: an alternative methodology for sample preparation

The aim of the present study was to compare the technique currently used for carrying out the microtensile bond strength (muTBS) test with an alternative method. Six human molars were sectioned transversally to obtain two specimens from each tooth: a 0.75-mm-thick slab of mid-coronal dentin, which presented an occlusal and a cervical surface (DS specimen); and the remaining section of the tooth with an exposed dentin surface (SS specimen). A self-etch adhesive system and four layers (2 mm each) of resin composite were applied to the sectioned surfaces by means of a custom-made special device, in order to obtain a cylindrical build-up. Each specimen was sectioned lengthwise to obtain multiple sticks. The end sections of sticks obtained from DS specimens were resin composite, whereas the middle section was dentin. The sticks obtained from SS specimens were half resin composite and half dentin. The specimens were fractured under tension. Data were subjected to a multilevel statistical model. The maximum load at break of SS specimens was higher than that of DS specimens. This modified methodology offers two main advantages over the traditional procedure: easier manipulation of the sticks; and the possibility of testing deep dentin.