The effect of a desensitizer and CO₂ laser irradiation on bond performance between eroded dentin and resin composite

Purpose. This study was aimed to evaluate effect of the desensitizing pretreatments on the micro-tensile bond strengths (μTBS) to eroded dentin and sound dentin. Materials and Methods. Forty-two extracted molars were prepared to form a flat dentin surface, and then they were divided into two groups. Group I was stored in distilled water while group II was subjected to a pH cycling. Each group was then subdivided into three subgroups according to desensitizing pretreatment used: a) pretreatment with desensitizer (Gluma); b) pretreatment with CO₂ Laser (Ultra Dream Pluse); c) without any pretreatment. All prepared surfaces were bonded with Single Bond 2 and built up with resin composite (Filtek Z250). The micro-tensile bond test was performed. Fracture modes were evaluated by stereomicroscopy. Pretreated surfaces and bonded interfaces were characterized by scanning electron microscope (SEM). The data obtained was analyzed by two-way ANOVA (α =0.05). Results. For both sound and eroded dentin, samples treated with desensitizer showed the greatest μTBS, followed by samples without any treatment. And samples treated with CO₂ laser showed the lowest μTBS. SEM study indicated that teeth with eroded dentin appeared prone to debonding, as demonstrated by existence of large gaps between adhesive layers and dentin. Conclusion. Pretreatment with Gluma increased the μTBS of Single Bond 2 for eroded and sound teeth. CO₂ laser irradiation weakened bond performance for sound teeth but had no effect on eroded teeth.