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Background/purpose: Ground section is the only way to study tooth enamel, and the conventional methods of making ground sections, grinding by hand or using a hard tissue microtome are either too time consuming or money costing. This study aimed to develop and assess a novel cutting machine in making ground sections and learning aid for dental students. Materials and methods: By using the novel cutting machine, the students cut the embedding teeth and got 50 μm ground sections efficiently. A series of fine/coarse combination stones were used for grinding the sections to uniform 20 μm thickness. Self-made ground sections were used in the lab class of tooth tissue. Questionnaires were designed to assess the participants’ attitude towards the cutting machine and their knowledge of the tooth tissue before and after making the tooth ground sections. Results: Our findings indicated that the novel cutting machine can act as an efficient tool to make tooth ground sections. Indeed, data indicated that making tooth ground section progress can assist students’ understanding of the structure and function of tooth and their pathology knowledge had improved. From a qualitative point of view, the students described making tooth ground section progress improve their practical ability and study interest in oral pathology. Conclusion: Overall, these findings indicate that our novel cutting machine can act as an efficient tool to make tooth ground sections and support dental students to study the pathology of the tooth hard tissue in a simple and functional way.

Metformin is an old and widely accepted first-line drug for treating type 2 diabetes. Our previous studies demonstrate that metformin can stimulate the osteo/odontogenic differentiation of human-induced pluripotent stem cell-derived mesenchymal stem cells and human dental pulp cells (DPCs). Due to the rapid dilution of metformin from the defect area, the aim of this study was to develop a drug delivery system with controlled release of metformin to promote cell viability and odontogenic differentiation of DPCs favoring dentin regeneration. Calcium phosphate cement (CPC) containing chitosan and metformin as a scaffold was synthesized. DPCs were seeded onto the scaffold, and the viability and proliferation were evaluated at several time points. For osteogenic differentiation analysis, alkaline phosphatase (ALP) activity was tested, cells were stained with Alizarin Red, and the expression of odontogenic markers was evaluated by real-time polymerase chain reaction. DPCs remained viable and attached well to the CPC-chitosan composite scaffold. Moreover, the addition of metformin to the CPC-chitosan composite did not adversely affect cell proliferation, compared to that of CPC control. Our data further revealed that the novel CPC-chitosan-metformin composite enhanced the odontogenic differentiation of DPCs, as evidenced by higher ALP activity, elevated expression of odontoblastic markers, and strong mineral deposition. These results suggest that the new CPC-chitosan-metformin composite is a highly promising scaffold with the potential for tissue engineering applications including dentin regeneration.

Background/purpose: Noncarious cervical lesions (NCCLs) are among the most frequent conditions requiring resin restorations. However, the major shortcoming of these restorations is limited longevity. The purpose of this study was to compare the clinical performance of self-etching (SE) adhesives with or without selective enamel etching in NCCLs. Materials and methods: An initial literature search, with strict inclusion and exclusion criteria, was conducted in MEDLINE, Web of Science, the Wiley Online database, and the Cochrane Controlled Trials Center. Eight trials were included. Restoration retention, prevalence of marginal defects, and marginal discoloration were evaluated. Data were analyzed using the Mantel–Haenszel method with 95% confidence intervals. Results: Results demonstrated that fewer marginal defects (P = 0.0001) and discoloration (P = 0.008) were observed with the selective enamel etching approach. The risk ratio (RR) values of the selective etching group and the nonselective etching group for marginal defects and discoloration were 0.58 (0.44, 0.77) and 0.48 (0.28, 0.83), respectively. For restoration retention, the differences between the two groups were not significant (P = 0.44). The RR values of the selective etching group and the nonselective etching group for restoration retention were 1.01 (0.98, 1.04) and 1.02 (0.96, 1.08), according to a fixed-effects model at 2- and 5-year observation time, respectively. Conclusion: Previous enamel etching resulted in fewer marginal defects and marginal discoloration, compared with using the SE approach alone. For restoration retention, the differences between the two groups were not significant. Additional longer follow ups and large-scale investigations are expected to assess possible advantages of selective enamel etching in NCCL restorations.

Long-term heavy alcohol consumption could result in a range of health, social, and behavioral problems. People who abuse alcohol are at high risks of seriously having osteopenia, periodontal disease, and compromised oral health. However, the role of ethanol (EtOH) in the biological functions of human dental pulp cells (DPCs) is unknown. Whether EtOH affects the odontoblastic differentiation of DPCs through the mechanistic target of rapamycin (mTOR) remains unexplored. The objective of this study was to investigate the effects of EtOH on DPC differentiation and mineralization. DPCs were isolated and purified from human dental pulps. The proliferation and odontoblastic differentiation of DPCs treated with EtOH were subsequently investigated. Different doses of EtOH were shown to be cytocompatible with DPCs. EtOH significantly activated the mTOR pathway in a dose-dependent manner. In addition, EtOH downregulated the alkaline phosphatase activity, attenuated the mineralized nodule formation, and suppressed the expression of odontoblastic markers including ALP, DSPP, DMP-1, Runx2, and OCN. Moreover, the pretreatment with rapamycin, a specific mTOR inhibitor, markedly reversed the EtOH-induced odontoblastic differentiation and cell mineralization. Our findings show for the first time that EtOH can suppress DPC differentiation and mineralization in a mTOR-dependent manner, indicating that EtOH may be involved in negatively regulating the dental pulp repair.

A new dimethacrylate monomer 9,9'-bis[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)phenyl] fluorene (3) with a molecular weight of 634 was synthesized in 51.4%yield by addition of a glycidyl ether group to 9,9'-bis(4-hydroxyphenyl) fluorene (1) bythe reaction of compound 1 with epichlorohydrin, and then introducing the methacrylatemoiety by the reaction of the epoxy group with methacrylic acid. The structure ofmonomer 3 was confirmed by FT-IR, 1H-NMR, mass spectra and elemental analysis.

The article focuses on the improved preparation of 2,4-Dimethylpyrrole. It states that the traditional methods to acquire 2,4-Dimethylpyrrole involves several steps including the construction of pyrroles skeleton, oximation of acetoacetic esters, and subsequent hydrolysis. The paper presents a two step method in which a readily available ethyl acetoacetic ester and a pyrrole skeleton which was elaborated by a one-pot reaction that include reduction, hydrolysis, and cyclization. The method is inexpensive and has an overall yield of 86%.

An abstract of the article "The Novel Usage of Thiourea Nitrate in Aryl Nitration" by Ge Meng, Mei-Lin Zheng, A-Qun Zheng, Mei Wang and Juan Shi is presented.