Objective To compare the centering ability of three rotary nickel-titanium instruments Reciproc,Protaper and WaveOne in resin-simulated curved root canals.Methods A total of 30 resin-simulated curved canals(curvature=30°)were di-vided into 3 groups(n=10 each)using the random number table.They were prepared with Reciproc(group R),Protaper(group P)and WaveOne(group W)respectively.Pre-and post-operative images were obtained by a digital camera at the fixed position, and superimposed through Photoshop.The center displacement between pre- and post-operative images were measured at 10 points beginning at 1 mm from the end point of the canal with the software Digimizer at a ratio of 1 to 1.The data were analyzed through one-way ANOVA and Student-Newman-Kuels at a significance level ofα=0.05.Results The central point was shifted laterally to the curve at 1,2,and 3 mm from the end point of the canal,while it shifted medially to the curve at 6,7,and 8 mm.The centering ability was better in groups R and W than in group P with significant differences noted(P <0.05).No sig-nificant difference was found in the centering ability between group R and group W.Also there were no significant differences in the centering ability at 4,5,9 and 10 mm among the three groups(P >0.05).Conclusion Reciproc and WaveOne have similar centering ability.They preform better in terms of centering location than Protaper,especially at the apex and the most curved part of the canal.

Objective To investigate the characteristics and influencing factors of infection in elderly patients with oral and maxillofacial surgery,and to explore the effect of infection on inflammatory response-related proteins,in order to guide the clinical treatment.Methods A total of 653 cases of patients aged more than 60 who were treated with oral and maxillofacial surgery during January 2004 to December 2015 in Shenzhen People's hospital was involved and divided into infected group (n =48) and uninfected group (n =605) according to whether postoperative nosocomial infection was occurred.The characteristics and influencing factors of infection were observed.A total of 171 cases of healthy volunteers whose age and sex were matched with patients were collected as control group.The expressions of inflammatory responserelated proteins in 3 groups were compared.Results The main site of postoperative nosocomial infection was lower respiratory tract,with 15 cases of patients,accounting for 31.3％.A total of 48 strains of pathogens was isolated,the main pathogenic bacteria were Streptococcus pyogenes,with 8 strains,accounting for 16.7％.Streptococcus pyogenes had high drug resistance to erythromycin and clindamycin,and had high sensitivity to penicillin G and meropenem.Aged more than 70,operation time more than 3 h,the primary diseases as malignant tumor were the independent risk factors for postoperative nosocomial infection (P ＜0.05).Blood interleukin (IL)-1,IL-2,IL-6,IL-10,tumor necrosis factor α (TNF-α),transforming growth factor β (TGF-β) and interferon-γ (IFN-γ) in infected group were more than uninfected group and control group.The differences were statistically significant (P ＜ 0.05).Conclusions The rate of infection in elderly patients with oral and maxillofacial surgery is still high in our hospital.The main site of infection is lower respiratory tract and the main pathogens were Streptococcus pyogenes.Aged more than 70,operation time more than 3 h,the primary diseases as malignant tumor were the independent risk factors for postoperative nosocomial infection.Infection can lead to peripheral inflammatory factor levels increase significantly.

Gardner syndrome is a rare disease in oral and maxillofacial diseases which is characterized by intestinal polyposis, multiple osteomas, skin and soft tissue tumors. Early treatment has a better prognosis; therefore the early diagnosis of Gardner syndrome is very important. Maxillofacial pathology always appears to precede the other pathologies, so the importance of early detection of the syndrome by dentists is also emphasized. This review summarizes the etiology of Gardner syndrome-related mutations and the clinical manifestations of Gardner syndrome characterized by oral and maxillofacial deformities, multiple gastrointestinal polyps, and desmoid tumour, and their associated treatment.

With the increasing development of digital technologies, digital surgical templates have been widely used in stomatology. However, the accuracy of digital surgical templates is always a consideration for many researchers and dentists. This article analyzed the factors affecting the accuracy of digital surgical templates and found that errors arise from six factors, including the design and manufacture of the templates, implant guide support, implant systems and guide systems, implant length, bone density and the clinical experience of the operator; this literature review aims to reduce or eliminate human factors and improve accuracy, objectivity and security in implant placement.

Objective: To compare the differences in the stress distribution in simulated first molars prepared with three rotary nickel-titanium instruments. Methods : Four simulated first molars were prepared without instruments and with Reciproc, WaveOne and Protaper. Before and after preparation, each simulated molar was scanned by Micro-CT. The data were imported to Mimics 16.0 software to establish three-dimensional models. Finite element analysis was processed with Abaqus 6.14 software under conditions of longitudinal and lateral load. Results: Under vertical load conditions, the maximum von Mises stress of the enamel increased by 1.36%, 21.48% and 20.99% in the Reciproc, WaveOne and Protaper groups, respectively, after preparation, while the maximum von Mises stress of the cementum increased by 55.98%, 41.18% and 33.04%, respectively, and the maximum von Mises stress of the alveolar bone increased by 45.55%, 40.37% and 24.09%, respectively. Under 45° lateral load conditions, the maximum von Mises stress of the enamel increased by 1.79%, -4.58% and 3.82% in the Reciproc, WaveOne and Protaper groups, respectively, after preparation, while the maximum von Mises stress of cementum increased by 16.33%, 7.58% and 4.32%, respectively, and the maximum von Mises stress of the alveolar bone increased by 46.82%, 36.40% and 8.29%, respectively. Under the same conditions, the von Mises stresses of the cementum and alveolar bones of the simulated molars were higher after preparation than before preparation, especially under lateral load conditions. The stress was focused on the border between the crown and the root. The von Mises stress of the cementum and alveolar bones increased much more in the Reciproc group than in the other two groups under both conditions. Conclusion The von Mises stress of simulated molars was greater after preparation than before preparation. The von Mises stress of the cementum and alveolar bones increased much more in the Reciproc group than in the other two groups.