Bonding of Adhesives to Er-YAG-laser treated Dentin

Objectives: The aim of this study was to investigate the effect of Er: YAG laser irradiation on the shear bond strength of four different adhesives to lased dentin and the ultrastructure of the resin-dentin interface. Methods:Superficial and deep dentin from human molars was used. Dentin specimens were treated either with carbide bur or with an Erbium: YAG laser. Two total-etch adhesives (Single Bond and XP Bond) applied with acid etching and two self-etch adhesives (Prompt L-Pop and Xeno III) were employed to bond the composite. The shear bond strength (SBS) was determined after 24 h of storage in water. Shear testing was conducted by means of a universal testing machine with a crosshead speed of 0.5mm/min. Failure patterns were analyzed using a stereomicroscope, for determination of the failure modes and samples were processed for SEM evaluation. A three-way analysis of variance (ANOVA) was performed. Multiple comparisons were done by Bonferroni test. Results:The main result was a significant effect of treatment method p<0.05 showing a difference between laser irradiation and carbide bur cut. Shear bond strength was not significantly influenced by dentin depth when the same treatment was used. The total-etch adhesive bonded significantly less effectively to lased than to carbide bur-cut dentin. The self-etch adhesive performed equally to lased as to bur-cut superficial dentin, but significantly less effectively to lased than to bur-cut deep dentin Also there was a significant effect of adhesives p<0.05 showing a difference between XP Bond and XenoIII. Conclusions:It is concluded that cavities prepared by laser appear less receptive to adhesive procedures than conventional bur cut cavities