Adhesion of self-etching systems on air-abraded dentine with modified Bioglass/PAA

Objectives: The aim of this study was to evaluate the 3-month bond strength durability of dentine pre-treated with different formulations of bioglass. The ultra-morphology and micropermeability of the interfaces were evaluated using confocal microscopy (CLSM). Methods: Thirty dentine crowns were bonded using two different self-etching systems (DBAs: Bond Force, Tokuyama Corp., Japan or G-Bond, GC Corp., Japan) after receiving one of six different dentine surface treatments: (1) Bioglass air-abrasion (BAG) with 10% polyacrylic acid solution (PAA-fluid); (2) BAG with deionised water (H2O); (3) BAG with 10% PAA-powder; (4) BAG with 40% PAA-powder; (5) 320 SiC abrasive-polished dentine . A 5mm incremental build-up was made using Filtek Z250 (3MESPE) and photo-cured for 30 seconds. Microtensile bond strengths (MTBS) were performed and results compared statistically using SPSS 16.0 (SPSS Inc., Chicago, IL, USA). As the normality of the data (Shapiro–Wilk W-test) and equality of the group variances (Levene test) were valid, the statistical differences between groups were identified by three-way ANOVA; adhesive system, dentine surface treatment and water storage were considered as independent variables (P < 0.01). Fisher's least significant difference (LSD) test isolated and compared the significant differences (P < 0.05) between groups. Additional dentine surfaces were conditioned and bonded as previously described. These were prepared for a pulpal-micro-permeability confocal microscopy study, sectioned, polished and observed using CLSM. Results: mean (SD) MTBS values for each group are shown in the table. The lowest micro-permeability was observed within the bonded bioglass air-abraded dentine. Conclusions: the dentine air-abraded with the bioglass/PAA technique increased statistically the bond strength of Bond Force compared to air-abrasion using bioglass only. However, after 3 months of PBS storage, Bond Force applied on bioglass/10% PAA-fluid showed no statistical reduction. G-bond, both when applied on bioglass/40% and bioglass/10% PAA-powder, showed no statistical reduction after 3 months of PBS storage.