Bonding of auto-adhesive luting materials to dentin after surface treatments

Objectives: To assess the effects of different mechanisms of dentin conditioning on the bonding performance of auto-adhesive luting cements to dentin. Methods: Flat dentin surfaces from twenty-four human molars were divided in four treatment groups: 1) no treatment (control); 2) etching with 36% H₃PO₄ for 15s; 3) etching with 0.1M EDTA for 60s; and 4) etching with Clearfil SE Bond Primer for 20s. Composite blocks (Tetric Ceram/Ivoclar Vivadent) were cemented to the treated dentin surfaces with the self-adhesive resin cements RelyX Unicem (3M ESPE) and Maxcem (Kerr), according to the manufacturer's instructions. Bonded specimens were sectioned into beams of 1.0 mm² cross-sectional area for microtensile bond strength (µTBS) evaluation. Beams were stressed in tension at 0.5 mm/min. Results were analyzed by 2-way ANOVA and post-hoc Schefee test (α=0.05). Results: Mean µTBS and standard deviations are listed (MPa). Within the same row, identical letters indicate no differences (P<0.05).

The resin bond to dentin was not affected by the type of cement (P=.1490) and was affected by the dentin conditioning (P<.0001). For RelyX Unicem, the highest µTBS were attained after SE Bond Primer and H₃PO₄ conditioning. H₃PO₄ acid etching prior to the application of Maxcem raised the resin-dentin bond strength in a statistically higher level as that of the control. Conclusions: When using these tested new auto-adhesive cements, the best bonding effectiveness was obtained by selectively acid-etching dentin prior to luting.