ABSTRACT
OBJECTIVES: This study examined the effect of the uncured dentin adhesives on the bond interface between the resin inlay and dentin. MATERIALS AND METHODS: Dentin surface was exposed in 24 extracted human molars and the teeth were assigned to indirect and direct resin restoration group. For indirect resin groups, exposed dentin surfaces were temporized with provisional resin. The provisional restoration was removed after 1 wk and the teeth were divided further into 4 groups which used dentin adhesives (OptiBond FL, Kerr; One-Step, Bisco) with or without light-curing, respectively (Group OB-C, OB-NC, OS-C and OS-NC). Pre-fabricated resin blocks were cemented on the entire surfaces with resin cement. For the direct resin restoration groups, the dentin surfaces were treated with dentin adhesives (Group OB-D and OS-D), followed by restoring composite resin. After 24 hr, the teeth were assigned to microtensile bond strength (microTBS) and confocal laser scanning microscopy (CLSM), respectively. RESULTS: The indirect resin restoration groups showed a lower microTBS than the direct resin restoration groups. The microTBS values of the light cured dentin adhesive groups were higher than those of the uncured dentin adhesive groups (p < 0.05). CLSM analysis of the light cured dentin adhesive groups revealed definite and homogenous hybrid layers. However, the uncured dentin adhesive groups showed uncertain or even no hybrid layer. CONCLUSIONS: Light-curing of the dentin adhesive prior to the application of the cementing material in luting a resin inlay to dentin resulted in definite, homogenous hybrid layer formation, which may improve the bond strength.
Subject(s)
Humans , Adhesives , Chimera , Dentin , Inlays , Light , Microscopy, Confocal , Molar , Resin Cements , ToothABSTRACT
Objective: To evaluate bond strength and interface of various dentin adhesives by a modified interface processing method. Methods:Nine extracted human molars were ground to expose fresh dentin surface. Three dentin adhesives (Single Bond, Clearfil SE Bond and Clearfil S3 Bond) were applied respectively and a block of composite resin was built up. The specimens were then stored in distilled water for 24 h at 37 ℃ and sectioned into beams of 0.9 mm×0.9 mm cross-sectional area. The microtensile bond strength was determined with Microtensile Tester(n=15). In addition, the bonding specimens were conditioned with 6 mol/L HCl, 5% NaOCl and 0.08 mg/ml hyaluronidase to observe the adhesive interfaces by SEM. Results: Significant differences in bond strength were observed among the three adhesives(P<0.05): SE Bond (45.06±5.29) MPa> Single Bond (35.50±6.40) MPa> S3 Bond (30.46±3.82) MPa. Single Bond showed resin tags about 9-12 μm long and gaps between hybrid and adhesive layers. No obvious boundary between hybrid layer and adhesive were observed for both SE Bond and S3 Bond, while the length of resin tags were 9-14 μm and 4-7 μm for SE Bond and S3 Bond respectively. Conclusion:The morphology of the bond interface of dentin adhesive has a relationship with the bond strength.