One-bottle self-etching adhesives applied to dentine air-abraded using bioactive glasses containing polyacrylic acid: An in vitro microtensile bond strength and confocal microscopy study

Objectives: The aim of this study was to test the microtensile bond strength (mu TBS) of two "simplified'' self-etching adhesives bonded to air-abraded dentine using experimental bioactive glass powders containing polyacrylic acid. Methods: Sound dentine specimens were air-abraded using a pure Bioglass 45S5 (Bioglass) powder or two Bioglass powders containing different concentration of polyacrylic acid (PAA: 15 wt% or 40 wt%). The bonding procedures were accomplished by the application of two self-etching adhesives (CS3: Clearfil S3 Bond; Kuraray, Osaka, Japan or GB: G Bond; GC Ltd. Tokyo, Japan). The resin-bonded specimens were cut in beams (0.9 mm(2)) and the mu TBS testing was performed after 24 h or 6 months of phosphate buffer solution (PBS) storage. The results were statistically analysed by three-way ANOVA and Student-Newman-Keuls test used (alpha = 0.05). Further bonded-dentine specimens were used for the confocal microscopy interfacial characterisation and micropermeability analysis. Results: The CS3 adhesive system achieved higher mu TBS than those attained in the specimens bonded with GB both after 24 h and 6 months of PBS storage. The CLSM analysis performed after 6 months of PBS storage indicated severe micropermeability within the bonded-dentine interfaces created using GB applied onto dentine air-abraded with Bioglass/PAA-15 and Bioglass/PAA-40. Conversely, CS3 exhibited no dye penetration (micropermeability) at the resin-dentine interface. Conclusion: It is possible to affirm that air-abrasion procedures performed using pure Bioglass or Bioglass containing 15 wt% PAA do not interfere with the immediate bonding performance of self-etching adhesives. However, the durability of the bonded-dentine interfaces created subsequent air-abrasion procedures using bioactive glasses will depend also upon the chemical composition of the self-etch adhesive systems. (c) 2012 Elsevier Ltd. All rights reserved.