Effects of different dentin bonding agents on nanoleakage and hybrid layer thickness

Effects of different dentin bonding agents on nanoleakage and hybrid layer thickness Dr. M. Ghavamnasiri* - Dr. F. Maleknejad* - Dr. H. Ameri** - Dr. MJ. Moghadas** *- Associate Professor of Operative Dentistry Dept. – Faculty of Dentistry – Mashhad University of Medical Sciences. **- Assistant Professor of Operative Dentistry Dept. – Faculty of Dentistry – Mashhad University of Medical Sciences. Background and Aim: Wetness of etched dentin surface is an important factor in the accomplishment of an effective bonding system, however the required wetness has not been recognized yet. Different dentin bonding systems need various degrees of wetness to create a hybrid layer with the ideal quality. The aim of this study was to evaluate the effects of the wetness of etched dentin surface on nanoleakage and hybrid layer thickness. Materials and Methods: In this experimental parallel study, three kinds of dentin adhesives were used: One – coat Bond, Single Bond and Prime & Bond 2.1 and also three methods of drying the dentin surface after acid etching were used: Wet (blot dried), Semidry (3 – second blast) and Dry (15 – second drying). Class V cavities were prepared on 54 sound extracted premolars. After filling with a flowable composite and using silver nitrate, the rate of nonoleakage and the hybrid layer thickness were measured by SEM. Data were analyzed using ANOVA, DUNCAN test and correlation coefficient test at 95% level of confidence. Results: Nanoleakage was observed in all samples as the more dryness of etched dentin surface, the more significant nanoleakage was occurred. Moreover, in the most dried samples, the hybrid layer thickness was decreased significantly. The least rate of nanoleakage was observed in One – Coat Bond system along with wet condition and the highest rate was in Prime & Bond 2.1 in dry condition. In all studied systems the least nanoleakage and the highest hybrid layer thickness was related to wet highest hybrid layer thickness was related to wet condition meaning that the more hybrid layer thickness, the better seal of dentin. Conclusion: 1 – Among the three tested dentin bonding systems, One – Coat Bond revealed the least rate of nanoleakage in wet condition. 2- The highest rate of nanoleakage was observed in Prime & Bond 2.1 system in dry condition. 3- There was statistically significant differences in nanoleakage rate of three different drying methods in each bonding system. 4- There was a significant correlation, in nanoleakage increase and hybrid layer decrease, between all three bonding systems and three dentin drying methods. Key words: Nanoleakage – Hybrid layer – Dentin.