Influence of bioglass/PAA on adhesion of resin-modified glass ionomer cements

Objective: to evaluate the effect of bioglass/PAA air abrasion on the bond durability of a RMGIC to dentin. The morphology and the micropermeability of the interfaces were evaluated using confocal microscopy (CLSM). Methods: thirty dentine crowns were bonded using the RMGIC, GC Fuji II LC (GC, United Kingdom Ltd. Newport, Pagnell, UK) after receiving one of six different dentine surface-treatments: (1) Bioglass air-abrasion with a solution of 10% polyacrylic acid (PAA-fluid); (2) Bioglass air-abrasion with deionised water (H2O); (3) Bioglass air-abrasion with a solution of 10%-PAA and subsequent etched using a 10%-PAA conditioner gel; (4) Bioglass air-abrasion and subsequent etched using a 10%-PAA conditioner gel; (5) Dentine polished with 320 SiC-abrasive paper and then etched using a 10%-PAA conditioner gel; (6) Dentine polished with 320 SiC-abrasive paper. A 5mm incremental build-up was made using Filtek Z250 (3MESPE) and photo-cured for 30 seconds. Microtensile bond strength was performed and the results were statistically compared using two-way ANOVA and Sidak's tests (p>0.05). Additional dentine surfaces were conditioned and bonded as previously described. They were prepared for a pulpal-micro-permeability confocal microscopy study, sectioned, polished and finally observed using a CLSM. Results: mean (SD) MTBS values (MPa) for each group are shown in the table; after 6 month of PBS storage, no statistical reduction was observed in the Bioglass air-abraded dentine with a solution of 10%-PAA and subsequently etched using a 10%-PAA conditioner gel (Group 3). The confocal micro-permeability investigation showed a very low micro-permeability within the interface of the bioglass air-abraded dentine and bonding agents. Conclusions: the air-abrasion performed with bioglass and 10%-PAA solution may increase the bond strength and the durability of the interfaces created using RMGICs applied as per manufactures' instructions.