Effect of pretreatment on Er:YAG laser-irradiated dentin

Erbium:yttrium-aluminum-garnet (Er:YAG) laser preparation of tooth cavities for restoration is an increasingly popular method, but its compatibility with existing composite material bonding protocols has not been fully defined. This study evaluated the effect of laser and etchant pretreatments on the performance of one-bottle self-etch adhesives in Er:YAG laser-prepared dentin. Eight groups of 20 extracted teeth were established to investigate bonding in tested dentin disks. Various combinations of laser preparation (with/without), pretreatment (none/acid-etch/low-fluence Er:YAG irradiation), and self-etching adhesive (G-Bond Plus or Xeno V) were tested. Samples were then restored with composite resin and subjected to a tensile bond strength (TBS) test. We also performed scanning electron microscopy (SEM) on dentin disks from some of these groups before and after adhesive application to evaluate their microscopic morphological appearance. Statistical analysis (Dunnett T3 test coupled with the general linear model at 5% significance level) revealed that the laser preparation of dentin did not impact on TBS (p = 0.914), whereas pretreatment with either phosphoric acid (p < 0.0001) or low-fluence Er:YAG laser irradiation (p < 0.0001) significantly increased TBS, although there was no difference between them in their respective elevation of TBS. SEM analysis demonstrated that both acid and laser pretreatments reduced irregularities and produced a more homogeneous surface. Er:YAG laser preparation does not compromise the efficacy of one-step self-etch dentin adhesives, and pretreatment with phosphoric acid or low-fluence Er:YAG laser can significantly increase the TBS of adhesion to this irradiated dentin.