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 ultra-structures 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 (30s) 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.

Objective:To examine the ultrastructure of resin-infiltrated sclerotic dentine following the application of an all-in-one self-etch dentin adhesive. Methods:Naturally-occurring, non-carious cervical sclerotic lesions on 10 extracted premolars were bonded using an all-in-one self-etch dentin adhesive(Adper Prompt L-Pop,3M ESPE, St Paul, USA).Artificially prepared wedge-shaped lesions were also made in 10 extracted sound premolars and restored using the same adhesive as the controls. The morphological change of dentin surface conditioned by the adhesive and 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, the sclerotic casts could not be totally dissolved by the self-etch adhesive. After restoration the resin tags were fewer and shorter in sclerotic dentin than those in sound dentin.Conclusions:Bonding to sclerotic dentin is different from that to sound dentin, and may be compromised by the fewer resin tags.

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.

Objective: To study the axonal effect and the expression of integrin α6β4 during Schwann cell(SC) differentiation and myelination. Methods: Schwann cells were dissociated from the sciatic nerve of neonatal Waster rats and neurons dissociated from spinal cord. Singal cultures and purified populations of SC were cocultured with NC. Four methods (contrast microscope, scanning electron microscopy(SEM), immunocytochemistry method and in situ hybridization ) were used. Results: The separately cultured Schwann cells showed MBP negetive by immunocytochemistry method. But cocultured SC were shown positive. SEM showed that Schwann cells' membrane loop progressively circumnavigated around the axon during myelination, which suggested that the non-myelinating SC(nMSC) transformed to myelinating SC (MSC). In situ hybridization showed integrin α6β4 positive signals only on the outer surface of the Schwann cell-axon unit in SC coculture with NC. Conclusion: The differentiation and maturation of SC depend on axon, and the activity of integrins is expressed by axon. Axonal contact induces the expression of α6β4 during SC myelination, which suggests that integrin α6β4 is an important mediator of interactions of myelinating SC with the basal limina.