Properties of Hybrid Layers with Different Dental Adhesive Systems

Objective:  To investigate the properties of the hybrid layer formed by using three different adhesive systems. Method: Class V cavities were prepared on the buccal surface of fourty extracted human premolars. The prepared teeth were randomly assigned into four groups according to the adhesive system [Optibond S (OS, total-etch); Optibond Versa (OV, two-bottles, self-etch); Single Bond Universal (SBU, one-bottle, self-etch) and Single Bond Universal with etchant (SBU + etchant)]. All cavities were restored with composite (Filtek Z350XT). The samples were sectioned, polished and pretreated to remove minerals, protein and water prior to SEM evaluation. Result: From the images, thickness of the hybrid layers was measured. Present of resin tags and adaptation failure were also recorded. The data obtained were analyzed using SPSS software version 12.0.1 for Windows. OS group showed the highest average hybrid layer thickness (4.34 µm), followed by SBU + etchant (3.06 µm), OV (1.91 µm) and SBU (0.95 µm). Both adhesive and cohesive failures were observed in SBU group. Clearly defined resin tags were seen in both OS and OV groups. Conclusion:   All the investigated adhesive systems were able to perform distinguishable actions as shown in the micro-morphological alteration and hybrid layer thickness. A two-bottle, self-etch adhesive (OV) was shown to the produce negligible adaptation failure compared to other adhesive systems in the present study. Combined all-in-one adhesive (SBU) was found to render a superior bonding performance in total-etch mode comparing to self-etch mode.