Towards a better understanding of the adhesion mechanism of resin-modified glass-ionomers by bonding to differently prepared dentin

Objectives The purpose of this study was to evaluate the bonding effectiveness of a resin modified glass ionomer (RMGI) to differently prepared dentin and how this restorative material interacts with these distinct substrates Also the potential adhesion promoting role of a polyalkenoic acid conditioner was assessed Methods Forty eight dentin surfaces were prepared from sound human molars and ran domly distributed among 6 experimental groups Fuji II LC (GC) was applied on bur cut (100 mu m diamond) fractured and Er YAG laser irradiated (200 mJ 10 Hz 31 4 J/cm(2)) dentin with or without the beforehand application of the aqueous polyalkenoic acid conditioner Cavity Conditioner (GC) After 7 days of storage in water at 37 degrees C specimens were prepared for microtensile bond strength testing (mu TBS) as well as for TEM characterization of the resultant RMGI dentin interface Statistical analysis of the mu TBS results was performed using ANOVA and Tukey s test (p < 0 05) Results The use of conditioner resulted in a significantly higher bond strength only when dentin was prepared by diamond bur (p < 0 05) Laser irradiation induced micro cracks on the dentin surface and led to the lowest bond strength irrespective of the use of conditioner (p < 0 05) Fuji II LC was able to partially demineralise (up to 2 0 mu m) and infiltrate bur cut and fractured dentin but no evident interaction was observed at the interface between the RMGI and laser irradiated dentin Conclusions Laser induced surface modifications impaired the interaction of the RMGI with dentin thereby negatively influencing its bonding effectiveness The use of a polyalkenoic acid conditioner remains crucial for the RMGI to bond effectively to bur cut dentin (C) 2010 Elsevier Ltd All rights reserved