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Purpose: To evaluate the tensile bond durability and ability of four MMA-based adhesive resins to prevent demineralization along the hybrid layer when exposed to a demineralizing solution. Materials and Methods: A PMMA rod was bonded to human dentin using one of four MMA-based adhesive systems: Super-Bond C&B (SB), SBP-40TX (SBP, experimental), M-Bond (MB), and M-Bond II (MB II). Bonded specimens were sectioned into 0.9 mm x 0.9 mm beams and subjected to microtensile bond strength (µTBS) testing after water storage at 37°C for 24 h or 10,000 thermal cycles. Data were analyzed with two-way ANOVA and Bonferroni's t-test. Fracture mode analysis of the bonding interface was performed using a scanning electron microscope (SEM) and statistically analysed using the chi-square test. To disclose the demineralization inhibition potential through formation of an acid-base resistant zone (ABRZ), the bonded interface was exposed to a demineralizing solution (pH 4.5) for 90 min, and then 5% NaOCl for 20 min. After argon-ion etching, the interfacial ultrastructure was observed using an SEM. Results: µTBS values without thermocycling were not significantly different (p > 0.05) among 4 adhesive resins. After thermocycling, a significant decrease in µTBS was found in MB and MB II (p < 0.001), whereas SB and SBP showed no significant change (p > 0.05). Failure modes were signiicantly different (p < 0.05). An ABRZ was seen in SBP, MB, and MB II, while this protective zone was absent in SB. Conclusion: Dentin bonding performance after thermocycling was material dependent in MMA-based adhesive resins. The ABRZ formation was only observed in the self-etching systems. [ABSTRACT FROM AUTHOR]

Objectives Biphasic calcium phosphate ( BCP) composed of 10% hydroxyapatite ( HA) and 90% beta-tricalcium phosphate has been developed. Recently, a strontium hydroxyapatite-containing collagen membrane ( Sr) was shown to stimulate early bone formation in rat calvarial defects at 4 weeks postoperatively, as compared with a cross-linked collagen membrane, for guided bone regeneration ( GBR). The objective of this study was to evaluate these novel biomaterials for GBR in relation to a non-cross-linked collagen membrane ( BG) and deproteinized bovine bone mineral ( BO). Materials and methods Twenty New Zealand rabbits were used in this study. Four defects of 7 mm in diameter were created in each rabbit, and three of the defects were treated with BG/ BO, Sr/ BO, and Sr/ BCP. Ten rabbits were sacrificed at 12 and 24 weeks, respectively. Histological and histomorphometric analyses were conducted. Volumetric densities of mineralized new bone ( MNB), bone marrow ( BM), residual grafting material ( RG), and non-mineralized connective tissue ( NCT) were determined for each group. Results After 12 weeks, Sr/ BCP yielded more MNB than BG/ BO and Sr/ BO with no significant difference among the three groups. After 24 weeks, however, Sr/ BCP demonstrated significantly more MNB than BG/ BO and Sr/ BO. Both after 12 and 24 weeks, Sr/ BCP showed significantly less RG than BG/ BO and Sr/ BO. There was a significant increase in MNB in Sr/ BCP from 12 to 24 weeks. Conclusions In defects grafted with BCP, more MNB was formed while less RG remained, than in defects grafted with BO. The Sr membrane was as effective as BG when comparing Sr/ BO with BG/ BO. [ABSTRACT FROM AUTHOR]