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Objective To investigate the antibacterial activity to Streptococcus mutans of a nisin⁃containing single⁃ bond universal adhesive. Methods Nisin was mixed into the bonding agent to produce concentrations ranging from 0.01 g/mL to 0.05 g/mL for the experiments, and adhesive without nisin was used as the control. Dentin⁃resin specimens were prepared for the microtensile strength test to evaluate changes in the bonding strength. The proper concentrations were selected for more tests. ① An agar diffusion test was applied with filter paper to detect the release of nisin, and adhesive without nisin was used as the negative control, 0.01 g/mL Nisin aqueous solution was used as the positive control. ② Solidification; resin adhesive specimens were prepared for the assessment of direct contact inhibition activity. ③ Confocal laser scanning microscopy was used to examine the effect of the adhesive on the biological film activity and the ability of Streptococcus mutans to produce extracellular polysaccharides. Results Nisin did not significantly reduce the bond strength of the modified adhesive at 0.01⁃0.03 g/mL (P < 0.05); these concentrations were selected for the subsequent antibiosis experiment. Rings could not be observed in the agar diffusion test, except for in the group of adhesive modified with 0.01⁃0.03 g/mL nisin. Resin adhesive with 0.01⁃0.03 g/mL nisin could significantly inhibit the proliferation of Streptococcus mutans on the surface of the specimens. The confocal laser scanning microscopy results indicate that only the adhesive resin modified with nisin could reduce the bacteria in the biofilm and the production of extracellular polysaccharides. Conclusion Single⁃bond universal adhesive with 0.01⁃0.03 g/mL nisin can inhibit the growth of Streptococcus mutans and its biofilms on the bonding interface, as well as decrease the production of extracellular polysaccharides, and thus has the potential to decrease the occurrence of secondary caries.

Objective The aim of this study is to investigate the roles of Notch signaling and autophagy on mineral trioxide aggregate (MTA) induced differentiation of human dental pulp cells (hDPCs). Methods Third molars from healthy human were collected and hDPCs were isolated by a combined digestion of collagenase Ⅰ and dispaseⅡ. Real time PCR were used to test the mRNA expression levels of alkaline phosphatase (ALP), runt⁃related transcription factor 2 (Runx2) and dentin sialophoprotein (DSPP) in MTA treated hDPCs in different time (24 h, 3 d and 7 d). The mineral⁃ ization nodules formed by hDPCs with or without MTA treatment were detected by Von Kossa staining. Expressions of Notch1, Jagged1, Hes1, LC3Ⅱ/LC3 Ⅰand p62 in wild type and MTA treated hDPCs were detected by western blotting. Results MTA extracted in a concentration of 0.1 mg/mL could promote the differentiation of hDPCs. Compared with that of wild type hDPCs, the expressions of Notch1, Hes1, or Jagged1 and p62 (P＜0.01) in MTA treated hDPCs were significantly increased. MTA treatment showed inhibition effects on autophagy flux similar to Bafilomycin A1, a specific inhibitor of fusion between autophagosomes and lysosomes. Conclusion MTA could promote hDPCs differentiation with highly relevant in stimulating Notch1⁃Jagged1⁃Hes1 signaling and inhibition of autophagy flux.

Objective To evaluatethe detection rate, typing, and therapeutic effect of second mesiobuccal canals(MB2) of first molars under dental operating microscope.Methods 88 maxillary molars with the presence of MB2 through cone beam computed tomography (CBCT) were collected, in which 68 were received root canal treatment and 20 were received root canal retreatment because of the missing canal of MB2 respectively. The type of mesiobuccal root canal in the former 68 maxillary molars were analyzed under CBCT. The 68 maxillary molars were divided into 2 groups, with 34 in each group. The experienment group received treatment under dental operating microscope, while the control group under naked eyes. MB2 detection rate, treatment and retreatment effect between two groups were compared. The latter 20 maxillary molars were also seperated into 2 groups, in which 10 cases were treated under microscope and 10 cases were treated under naked eye. The effect of retreatment was observed.Results The type of mesiobuccal root canal in 68 maxillary molars under CBCT were mainlytypeⅡand typeⅢ, with the proportion of 77.9% (53 cases) and 22.1% (15 cases) respectively. The detection rate of MB2 in the experimental group was 100%, and 91.2% (30 cases) in the control group, a statistical difference can be found between 2 groups (P < 0.05). 97.5% (33 cases) of the experimental group was successfully treated, and 79.4% (27 cases) for the control group (P < 0.05). The success rate of retreatment under microscope was 60% (6 cases), which was significantly higher than that of the naked eye (P < 0.05). In 3-month and 6-month follow-up, the treatment effect in experimental group was significantly better than the control group (P < 0.05).Conclusion Dental microscope can help to increase MB2 detection rate and improve treatment and retreatment effect.