Hybridization quality of adhesive systems according to dentin interaction

Objectives: This study evaluated the formation and quality of hybrid layers (HY) between different adhesive systems and dentin.

Methods: Fifteen third molars were trimmed to expose two adjacent flat surfaces of middle dentin, which were hybridized using the following adhesive systems: Adper Prompt (ADP), XENO III (XE), Clearfil SE Bond (SE), Adhe SE (ADSE) and Single Bond (SB). A block of dentin/resin/dentin was made by filling the two adjacent slices with a low viscosity resin, which were light–cured. Each block was mesio-distally sectioned producing 12 interfaces per adhesive. Four interfaces were stained with ammoniacal silver nitrate solution; four, with silver methenamine solution and four were used as control. All bond interfaces were observed under SEM.

Results: After ammoniacal silver nitrate solution, SB showed a greater intensity of silver grain deposition than other systems. SE and ADSE presented similar but fewer silver grain depositions. XE and ADP showed moderate amounts of silver grains in the HY and also inside the adhesive layer. After silver methenamine solution, SB presented silver deposits predominantly under HY at the area nearest to the mineralized dentin. SE presented fewer electron-dense points than other systems at the base of the HY. ADSE showed more intensified electron-dense points than SE. XE and ADP presented massive silver points within the base of the HY.

Conclusions: Two-bottle self-etch adhesive systems showed less electron-dense points inside the interdiffusion zone and under the hybrid layer, suggesting a better quality interaction with dentin compared to etch-and-rinse and all-in-one adhesives.