[Effect of acid etching time on bonding interface of non-carious cervical sclerotic dentin].

OBJECTIVE: To examine the effect of acid etching time on the bonding interface of non-carious cervical sclerotic dentin. METHODS: Twenty extracted premolars with non-carious cervical lesions were randomly divided into two groups, the lesion surface was conditioned with Scotchbond Multi-Purpose Plus dentin bonding system. The etching time was 15 s and 30 s respectively. The bonding interface ultrastructures were compared with SEM. RESULTS: In sclerotic dentin (15 s), the hybrid layer was visible, with minimal resin tags in the dentinal tubules and, when presented, they were shorter. Doubling the etching time (30 s) resulted in more resin tags with an hybrid layer formation on peritubular dentin. CONCLUSION: Doubling the etching time improved the ultrastructure of sclerotic dentin-resin bonding interface, and could be an efficient way to improve the bonding effect.

[Ultrastructural study of sclerotic dentin in non-carious cervical lesions disposed by a total-etching dentin adhesive].

OBJECTIVE: To examine the ultrastructure of resin-infiltrated sclerotic dentine following the application of a three-step total-etching dentin adhesive. METHODS: Naturally-occurring, non-carious cervical lesions on extracted premolars were bonded using a total-etching dentin adhesive-Scotchbond Multi-purpose. Artificially prepared wedge-shaped lesions were also made in sound premolars and restored using the same adhesive as control. The morphological change of the dentin surface conditioned with the etchant, and the hybrid zone and resin tags in the dentin-resin interface were studied by SEM. RESULTS: Most dentinal tubules were obliterated by rod-like sclerotic casts in the non-carious cervical lesion, and could not be dissolved by Scotchbond Multi-purpose etchant. Both the hybrid zone and resin tags were observed in sclerotic dentin after restoration, although the resin tags were fewer and in lack of communications, the length of resin tags and the thickness of the hybrid zone were almost similar to those of the sound dentin. CONCLUSION: Bonding to sclerotic dentin is different from sound dentin, and may be compromised by the fewer resin tags and communications.