Students are often apt to make mistakes in operative dentistry and endodontics experiments because of the complex experiment procedures and various instruments.Practice shows that it can effectively prevent and correct many mistakes by reasonably using mistake-demonstration method in experiment teaching of operative dentistry and endodontics.

Objective:To investigate the protective effects of quercetin on the periodontal tissue in Wistar rats with periodontitis. Methods:30 Wistar rats were randomly divided into 3 groups(n =1 0):Control group (group N),ligation group(group L)and liga-tion +quercetin group(group LQ).Bilateral first molars of the rats in group L and LQ were cervically ligated by an orthodontic wire with the diameter of 0.2 mm.The rats in group LQ were then treated with quercetin by gavage at 50 mg/(kg·d)after ligation.After 8 weeks,the rats were killed.Continuous slices of the periodontal tissue were made for HE staining and immunohistochemistry stai-ning.The morphological changes and the expression of TNF-αand COX-2 in the periodontal tissue were observed under light micro-scope.Results:The inflammatory cells and periodontal pocket were observed in group LQ were less than those in group L.The levels of TNF-α,COX-2 in group LQ were lower than that those in the group L(P <0.05).Conclusion:Quercetin has a protective effect on the periodontal tissues of Wistar rats with periodontitis.

In recent years,the increasingly intense doctor-patient relationship has become a major impact on health development and harmonious society construction in China.From the perspective of emotional interaction,this article focuses on improving medical techniques,establishing the awareness of comprehensive communication,attempting role exchange,showing humanistic concern,and expanding communication methods,in order to build an effective multidimensional doctor-patient communication framework and establish the new doctor-patient relationship with mutual respect,understanding,trust,and sympathy.

Host modulation therapy (HMT), as a treatment concept for periodontitis, aims to modulate the host immune responses during the pathogenesis of periodontitis. Various drugs have been evaluated as HMT, including subdose doxycycline (SDD), nonsteroidal anti-inflammatory drugs (NSAIDs), bisphosphonates, and cytokine receptors, to modify or modulate inflammatory mediators and associated signaling pathways in the immune-inflammatory response, as well as connective tissue breakdown and bone resorption. SDD, a member of the tetracycline drug family, has been reported to improve periodontal treatment outcomes by inhibiting periodontal breakdown through inhibiting MMPs. NSAIDs may suppress periodontal inflammation by reducing cyclooxygenase-2(COX-2) activity. Combined application of SSD and NSAIDs may achieve a better clinical outcome. Recent studies of HMT treatment have focused on the prevention of excessive inflammation by regulating mediators using endogenous lipid mediators. Local administration of bisphosphonates and histone deacetylase inhibitors can inhibit osteoclast activity and regulate bone tissue remodeling. Currently, SSD is approved by the FDA for periodontal treatment. Other drugs, such as COX-2 selective inhibitor, nonsteroidal anti-inflammatory drugs, bisphosphonates, triclosan and iNOS inhibitors, have good application prospects in the prevention and treatment of periodontal disease, and the mechanism and side effects of these drugs remain to be further investigated.

BACKGROUND:Inflammation affects the osteogenic differentiation of periodontal ligament stem cells,and the osteogenic ability and autophagy level of periodontal ligament stem cells are closely related.However,there are no relevant reports on whether inflammation affects the osteogenic ability and autophagy level of periodontal ligament stem cells at different stages of osteogenic differentiation. OBJECTIVE:To explore alkaline phosphatase expression and autophagy periodontal ligament stem cells levels in periodontitis and normal conditions. METHODS:Periodontal ligament stem cells from normal and periodontitis patients were isolated and cultured,and underwent Vimentin,pan-CK,and Stro-1 fluorescence staining.At 3,7,and 14 days of osteogenic differentiation,western blot assay was used to detect the protein expression levels of alkaline phosphatase,LC3B,Beclin1,and ATG5 in normal and inflammatory periodontal ligament stem cells.The mRNA expression levels of alkaline phosphatase,bone sialoprotein,osteocalcin,Runx2,LC3B,Beclin1,and ATG5 were detected by real-time PCR. RESULTS AND CONCLUSION:(1)Stro-1 was positive,Vimentin was positive,and pan CK was negative in periodontal ligament stem cells.(2)At 3,7,and 14 days after osteogenic differentiation,compared with normal periodontal ligament stem cells,the mineralization nodules formed by periodontal ligament stem cells from inflammatory sources were significantly reduced(P<0.01);the expression of alkaline phosphatase protein and mRNA was significantly lower(P<0.05);the mRNA expression levels of bone sialoprotein,osteocalcin,and Runx2 were significantly decreased(P<0.05).(3)At 7 and 14 days after osteogenic differentiation,compared with normal periodontal ligament stem cells,the expression levels of ATG5,LC3B,and Beclin1 proteins and mRNA of periodontal ligament stem cells were downregulated(P<0.05).These findings suggest that inflammation reduces the activity of periodontal ligament stem cells in mineralizing nodule formation and the expression of alkaline phosphatase and weakens the autophagy potential of periodontal ligament stem cells at 7 and 14 days after osteogenic differentiation.