Performance of different adhesive systems on bond strength to simulated hypersensitive dentin treated with Nd:YAG laser irradiation

Abstract

Nd:YAG laser irradiation as a pretreatment has favored bond strength (BS) of a self-etch adhesive system plus a resin composite to simulated hypersensitive dentin, even in face of the persistence of the etiological factor of dentin exposure. It is unknown, however, if the same behavior would be expected when different adhesive systems, such as the simplified etch-and-rinse ones, whether or not containing glutaraldehyde, are applied. Immediate and late performance of different adhesive systems on BS of a resin composite to simulated hypersensitive dentin irradiated with Nd:YAG laser will be, thus, evaluated. Superficial occlusal dentin of third molars (n=42) will be submitted to a 600-grit SiC paper (1 min) and to an acidic challenge with citric acid (6%; 1 min; simulated hypersensitive dentin: open tubules), and, afterward, it will be, or not (C: control, n=21), irradiated with Nd:YAG laser (L: Laser, 1.5 W, 10 Hz, 100 mJ, 4 irradiations of 15 sec each; n=21). Composite buildups will be constructed with Filtek Z350 following the application of one of the adhesive systems ClearfilTM SE Bond® (CSEB; C.CSEB, n=7; L. CSEB, n=7), AdperTM Single Bond 2® (ASB2; C.ASB2, n=7; L.ASB2, n=7) or Gluma Comfort® Bond + Desensitizer (GCB+De; C.GCB+De, n=7; L.GCB+De, n=7). After 24 h (distilled water/37ÚC), specimens will be sectioned in beams, which will be tested (¼TBS; 0.5 mm/min) immediately or after 6 months aging. An extra tooth for each group will be treated just like the others, but the fluorescent dye rhodamine B will be previously added (0.02 mg/mL) to the adhesive systems to allow a qualitative evaluation of the adhesive interface by means of Laser Scanning Confocal Microscopy. If obtained BS data are considered normal and homogeneous, a three-way ANOVA and a subsequent analysis of multiple comparisons, if necessary, will be applied, with a significance level of 5%.