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Morphology of Hybrid Layer and Resin Tags of Quadrant UniBond
P.Suppa, C. Nucci*, S. Chersoni, L. Breschi, C. Prati
University of Bologna Italy
Introduction: The aim of this study was to evaluate the hybrid layer (HL) ultramorphology of a bonding system.
Method: Transversal sections of recently extracted teeth were obtained using a diamond disk. A standard smear layer was created by silicone-carbide paper (#600 grid) under water irrigation. Dentin was etched with 20% H3 PO4 (Quadrant Total Etch, Cavex Holland) for 15s. Quadrant UniBond (Cavex Holland) primer and bonding were applied on dentin surface in association with a composite (Quadrant Universal LC, Cavex Holland) according with manufacturers' directions. Some samples were longitudinally sectioned and prepared for SEM observation in order to evaluate the thickness of HL. Other samples were diagonally sectioned to evaluate the thickness of peritubular resin-interdiffusion zone. The diagonal section increases the visible thickness of HL and enables the observation of the resin infiltration at different levels.
Results: In longitudinal section the thickness of hybrid layer ranged from 2 to 7 mm. In diagonal section is possible observe the passage from a complete HL (near the interface with adhesive) to a partial HL (near the dentin) in witch resin tags ware rounded by peritubular resin-interdiffusion dentin zone. Resin transversal septa were visible along the length of resin tag and are probably in relationship with the later branches. A central hole was present at the top of the tag. Voids were sometimes visible along the interface. Resin tags were also observed in correspondence of gaps and voids, suggesting that several gaps were related to preparation artefacts.
Conclusion: Quadrant UniBond system is able to create a great number of resin tags resulting in strong connections with the deeper part of dentinal tubules.
Incomplete hybrid layer may affect the dentin interface but did not influence resin tag formation.
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