Applications Of Confocal Laser Scanning Microscopy To Cervical Sclerotic Dentin Bonding

Background: Non-carious cervical sclerotic lesions were called cervical wedge-shaped defects of tooth that had multi-factorial etiologies and higher incidence. The hyper-mineralized surface layer was presence and the lesion dentin was semi-translucence, so it was also called sclerotic dentins. Sclerotic dentin is the presence of sclerotic cast within dentinal tubules and hyper-mineralized surface that precluded optimal resin infiltration into the dentinal tubules. It is difficulty in clinic that sclerotic dentin is as a relevant bonding substrate.Objective: Observed sclerotic dentin interface and interfacial nanoleakage of bonding used total-etching system and self-etching system under confocal laser scanning microscope (CLSM).Study 1 Observation in sclerotic dentin interface of bonding under CLSMMethods: A total of 12 maxillary bicuspids with non-caries, natural cervical sclerotic lesions were divided into three groups. The sclerotic dentin was bonding with Single Bond (SB, total-etching adhesive), Clearfil SE Bond (CB, two-step self-etching) and Xeno III (XB, one-step self-etching) according to the manufacturer's instruction. Artifically wedge-shaped lesions were made in sound maxillary bicuspids and bonded using the same bonding adhesive as control groups. The primer component was labeled with Rhodamine B Isothiocyanate. CLSM observed hybrid layer and resin tag of dentin bonding interface.Results: Two-way ANVOA revealed significant influence of both the type of dentin and the bonding adhesive systems tested on resin tag and hybrid layer. Resin tag and hybrid layer in total-etching adhesive (SB) were longer and thicker than in self-etching adhesive (CB, XB), whatever in normal dentin or sclerotic dentin; while the resin tag and hybrid layer thickness were similar in two kind self-etching adhesive. Resin tag and hybrid layer were longer and thicker in normal dentin than in scleroticdentin using the same bonding adhesive system (except for XB adhesive).Study 2 Observation interfacial nanoleakage in sclerotic dentin bonding under CLSMMethods: 12 maxillary bicuspids with non-caries, natural cervical sclerotic lesions were divided into three groups. The sclerotic dentin was bonding with SB, CB and XB according to the manufacturer's instruction. Artifically wedge-shaped lesions were made in sound maxillary bicuspids and bonded using the same adhesive as control groups. The apical foramens were occluded with self-curing resin. Six specimen groups were individually exposed to 0.1% rhodamine B in 50% alcohol solutions for 24 hrs. Then the teeth were section using slowly saw and observed the interfacial bonding of the specimens under CLSM.Result: Two-way ANVOA revealed significant influence of both the type of dentin substrate and the adhesive systems tested on the lengths of the dye-penetrated pathways, representing the amount of nanoleakage. The lengths of the dye-penetrated pathways were longer in total-etching adhesive (SB) than in self-etching (CB, XB), whatever in normal dentin or sclerotic dentin; while the extension of nanoleakage were similar in two kind self-etching adhesive. In self-etching adhesive (CB, XB), the amount of nanoleakage were higher in normal dentin than in sclerotic dentin. On the other hand, it is no statistical significance that the amount of nanoleakage in normal dentin and sclerotic dentin using the total-etching adhesive (SB).Conclusion:The resin rags were fewer and shorter and the hybrid layers were thinner in sclerotic dentin than in normal dentin. When bonding the same type dentin substrate, the resin rags were shorter and the hybrid layer thinner in used self-etching adhesive than total-etching adhesive.The nanoleakage phenomenons of bonding interface were observation in three bonding adhesive. In sclerotic dentin bonding interface, these nanoleakage phenomenons were located between resin and normal dentin.