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.

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.

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.