Tooth extraction is the most common and basic operation in oral surgery, with the advancement of medicine, the instruments, the methods and the concept of minimally invasive have been developed rapidly in tooth extraction. This paper focuses on minimally invasive technology in the use of tooth extraction, so it provides some reference for the proper application and promotion in tooth extraction.

Abstract：Objective To investigate the presence and distribution of extraradicular biofilm on the apical root surfaces of human teeth with persistent periapical periodontitis. Methods Ten apex samples of single-rooted teeth with persistent periapical periodontitis were collected during root-end surgery. Five single-rooted teeth extracted for orthodontic reasons were selected as controls. All samples were initially evaluated using scanning electron microscopy after freeze-drying. The same samples were then processed with Brown and Brenn-modi?ed Gram staining. Results The root outside surfaces of teeth extracted for orthodontic reasons were covered by fibers and there was no cementum resorption or microorganisms. Extraradicular biofilm and cementum resorption were found in all teeth with persistent periapical periodontitis. The extraradicular bacteria were predominantly rods and filaments, and surrounded by a varying amount of amorphous extracellular material. Conclusions The extraradicular biofilm may be one of the important factors which cause persistent periapical periodontitis.

PURPOSE:To explore the expression and significance of Caspase-8 in the labial glands of patients with primary Sjogren’s Syndrome(pSS). Analysis the relationship between the expression of them and the clinical manifestations in pSS.METHODS:Fivty-five cases with pSS and fifteen controls were collected.Immunohistochemistry and Western blotting were used to examine Caspase-8 protein in labial glands of two groups,the IOD and the A were measured and the data were analyzed by statistical analysis.RESULTS:The expression of Caspase-8 protein in pSS was positively correlated with the disease course and significantly higher than those in control group(P<0.05),but has no correlation with the other clinical manifestations.CONCLUSIONS:The expression of Caspase-8 in pSS was increased,which was related to the disease course. Apoptosis pathway mediated by Caspase-8 may contribute to the formation and progression of pSS.

　Objective　 To investigate the effect of inhibition of CXCR4 antagonist AMD3100 on biological behavior of oral squamous cell carcinoma(OSCC) cells. Method MTT assay was used to evaluate AMD3100 influence on proliferation of tumor cells. Chemotaxis and migration response to inhibition of the specific CXCR4 antagonist AMD3100 was detected by chemotaxis assay. Results 1) In MTT assay, recombinant SDF-1 stimulated proliferation of tumor cells, and the availability of AMD3100 inhibited proliferation. 2) The chemotactic migration of OSCC cells could be induced by SDF-1. AMD3100 can inhibit the chemotaxis and invasion metastasis by blocking CXCR4 receptors. Conclusion The interaction of CXCR 4/SDF-1 system could be suppressed by AMD3100, and it can be a meaningful therapeutic target and strategy.

Objective To construct collagen/hyaluronic acid polyeletrolyte multilayer films on the surface of pure titanium disc and to evaluate its biocompatibility. Methods Pure titanium disc was first ground, polished and acid-etched with a mixture of H2SO4/H2O2, and then a basal surface with plenty of hydroxy group was obtained (set as control group). Collagen type Ⅰand hyaluronic acid was introduced onto this basal surface using layer by layer technique (set as test group). Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measurement were used for surface characterization. Pre-osteoblasts were seeded on these 2 groups’ discs, and then cell attachment, cell proliferation and cell differentiation were evaluated. Results SEM analysis demonstrated that the pure titanium discs in the 2 groups both had very smooth surfaces, and were also covered with different granules in nano size. However, the nanoparticle of the control group was much bigger than that of the test group. XPS analysis showed that the element nitrogen content of the test surface dramatically increased with deposition number. Contact angle measurement showed that surface wettability of the test surface was dramatically altered with the deposition number. Nevertheless, the contact angle of the test surface was less than that of the control surface. Cell attachment and cell proliferation were much stimulated in the test group. Meanwhile, the cells grew on the surface of test group showed much stronger differentiation ability. Conclusions Collagen typeⅠand hyaluronic acid was successfully constructed on the titanium surface, and this coating promoted cell growth, showing good biocompatibility.

Objective To investigate effects of rapid and slow maxillary expansion protocols on the levels of alkaline phosphatase (ALP). Methods Thirty patients (mean age 10.2years) were randomly divided into 2 groups: rapid maxillary expansion group(n = 15) and slow maxillary expansion group (n = 15) via Hass appliance. ALP activity was measured by a full automatic biochemical analyzer at the following time points: before activation, 1 week after activation, 1week, 4 weeks, 8 weeks,12 weeks in retention period. The clinical parameters, gingival index (GI) and periodontal depth (PD) were also recorded accordingly. Results No statistical difference was found between the two groups in terms of GI and PD with the exception of GI at 1 week after activation. ALP levels were significantly higher in rapid maxillary expansion group than those in slow maxillary expansion group from 1 week after activation to 4 weeks in retention, but there were no significantly difference between the two groups after 8 weeks in retention. Conclusion ALP in gingival crevicular fluid may be involved in the periodontal tissue remodeling, and the slow maxillary expansion could result in light and continuous force which might be more favorable to periodontal tissue.

Methods: The obturators rehabilitating the upper airway was reconstructed based on the CT graphs of a patient after unilateral complete resection of maxilla and the airflow was numerically simulated using the method of CFD. Results After restoration with high open, high closed, medium open, medium closed, low open, low closed obturators respectively, the airflow trends in both inspiration and expiration phases were obtained; the comparison of velocity contours, vorticity contours and area for each cross-section between the healthy side and the affected side was made. Conclusions Rehabilitation of various obturators cannot change the flow pattern of airflow in the cavity, and closed type can fill the defected cavity, thus changing the length-depth ratio and the low-velocity vortex area. Medium closed type ones are recommended as they can reduce the vorticity area substantially during both the inspiration and expiration phases.

Objective　To provide a database for orthodontic treatment by calculating the cephalometric standard value. Methods　Cephalograms taken from 42 She adults with normal occlusion were traced and examined using Ricketts analysis. Results　The cephalometric standard value of She adults was achieved by Ricketts analysis. She women’s Mand Plane to FH and Lower Face Height increased significantly compared to the man. Conclusions　The majority of She people have long faces with a vertical growth pattern. The women’s 1/3 lower face height is more than that of man.

Objective　To evaluate the effect of coronectomy for removal of mandibular wisdom teeth. Methods　The literatures were retrieved with computer about coronectomy from PubMed, Embase, Web of Science, CENTRAL, SIGLE, CNKI and CBM. The data extraction and quality assessment were analyzed by two reviewers independently using software RevMan5.1. Results　Four studies met our inclusion criteria with 401 teeth in Coronectomy group and 539 teeth in total removal group. Meta analysis showed: The RR (coronectomy vs. total removal) was 0.11 (95% CI = 0.03-0.36, P = 0.0003), 1.03 (95% CI = 0.54-1.98, P = 0.93), 0.55 (95% CI = 0.28-1.05, P = 0.07), and 1.14 (95% CI = 0.57-2.30, P = 0.71) for inferior alveolar nerve injury, post-operative infection, dry socket, and pain at 1 week after surgery, respectively. Conclusion　Coronectomy appears superior in reducing inferior alveolar nerve damage and could be used in clinical practice for third molar extractions with high risk of nerve injury.

Objective　To discuss the clinical effects of nitrous oxide / oxygen inhalation conscious sedation techniques on extraction. Methods 50 cases of bilateral mandibular third molar extraction and 50 bilateral orthodontic meiotic extraction patients were required. Nitrous oxide / oxygen inhalation conscious sedation and local anesthesia were performed on one side of one patient randomly, which was the experimental group, and the other side was subjected to extraction under local anesthesia only, working as the control group. The changes of blood pressure, heart rate and oxygen saturation in the extraction process were recorded. The pain level was analyzed with visual analogue scale（VAS）. Results　As for patients subjected to two different anesthetic methods in the process of tooth extraction, there was statistically significant difference in sedation analgesia, vital signs assessments（P＜0.05）. Conclusion　Nitrous oxide / oxygen inhalation conscious sedation, which has a good sedative and analgesic effects, is safe and effective in reducing the patient's pain and fear in extraction, thus worth wide clinical use.

Objective: To compare the satisfaction and masticatory efficiency of lingualized and semi-anatomic occlusal dentures. Methods: Eighteen edentulous patients with severe resorption of residual ridge were treated with semi-anatomic occlusal dentures or lingualized occlusal dentures for three months. Then they changed to wear another type of occlusal dentures for three months too. The satisfaction was assessed with satisfaction questionnaires and the masticatory efficiency was measured after each denture was worn for one and three months respectively. Results: Compared with semi-anatomic occlusal dentures, the stability of lingualized occlusal dentures was significantly better （P<0.01）. There was no significant difference in masticatory efficiency and masticatory period time between lingualized occlusal dentures and semi-anatomical occlusal complete dentures（P＞0.05）. Grinding time of wearing lingualized occlusal dentures was less than that of semi-anatomic occlusal dentures. Conclusions: Lingualized occlusal dentures can improve the performance of dentures by enhancing their stability and comfort for edentulous patients with severe resorption of residual ridge.

Abstract: Objective To evaluate the sealability of zinc oxide-eugenol-based root canal sealers of different viscosities. Methods: 60 extracted human single-rooted teeth were selected and randomly divided into six groups (n=10). The root canals were respectively filled with Zinc Oxide-Eugenol sealers and Cortisomol sealers of different viscosities. The teeth were split along long axis after dye penetration. The lengths of root apical dye microleakage were measured with stereopsis microscope. The interface of the dentins and the sealers was observed by the SEM. ANOVA of the SPSS12.0 was used to compare the differences. Results: There were differences among groups of Zinc Oxide-Eugenol sealers and Cortisomol sealers of different viscosities (P<0.05). Conclusion: The increment of the viscosity of zinc oxide-eugenol-based root canal sealers can increase the apical sealing ability of sealers in this experiment.

Abstract: Objective To evaluate the nickel titanium instruments fracture using two steps in root canal preparation. Method: Six hundred anterior teeth were selected. The teeth were divided into two groups, and there were 300 teeth in each group. One step group (control group), which prepared the root canal only once by ProTaper nickel—titanium files (S1-Sx-S2-F1-F2), and another group (experimental group) which prepared the root canal twice (First time:S1-G Grill-S2;Second time:F1-F2). The data were analyzed by SPSS18.0 software package for chi square test. Results: The incidence of instruments fracture and the length of instrument fracture part showed significant differences (p<0.05) between two groups. There were no significant differences in the length of root canal (P > 0.05) between two groups though the incidence of the experimental group instrument fracture was lower than that of control group. The majority of the instruments fracture frequently occurred in mandibular molars, in which there were 36(76.6%)fractures, especially in mesial root canals; and there were 28(59.6%)fractures in the midpoint of the curvature and 41 (87.2%) in quite complex canals with curvature more than 30。.Conclusion: Two steps preparation used in root canal therapy could decrease the incidence of instruments fracture. It is a recommended method to do two steps preparation combining with clinical practice.

Objective To evaluate short-term clinical performance of single LAVA zirconia crowns for restoration of anterior teeth. Methods 56 cases of anterior teeth defect patients received LAVA zirconia all-ceramic single crown restorations. Clinical follow-up survey of 3 months, 6 months and 12 months after restoration were processed according to the modified USPHS criteria. Results Within 12 months, 56 patients with 85 LAVA zirconia restorations have met Bravo standard. Color matching rate of these restorations reached 97.6% of Alpha standard, and appearance, marginal fit, materials reached 97.6%, 84.7%, 95.3% respectively. Conclusion LAVA zirconia crown is a good choice for restoration of anterior teeth.

[Abstract] Objective To evaluate clinical effect of calcium hydroxide in controlling the EIAP. Methods 386 cases, which were diagnosed as pulpitis and periapical periodontitis with EIAP were selected. They were randomly divided into experimental group (calcium hydroxide) and control group (camphor phenol+ iodoform) with 193 cases in each group. The materials were inserted into the canal root and then to observe whether the EIAP was eliminated after using material in root canal. Results The success rate of mild and moderate cases in experimental group was 92.8% and 94.4% respectively, significantly better than the 82.3% and 65.2% in the control group（P＜0.01). There were no differences between the groups of patients with severe pain(P＞0.05).Conclusions Calcium hydroxide paste is an ideal root canal disinfectant, which can control the EIAP effectively.

Objective： The purpose of this study was to investigate and analyse the prevalence of malocclusion among children in primary dentition in the area of Shanghai. To provide theoretical basis for the establishment of children's oral health care measures. Methods： The investigation of occlusion in primary dentition on 2744 cases of children aged 3-6 of Shanghai was carried out by pediatric specialists.Results： The prevalence of malocclusion in primary dentition in Shanghai was 69.64% ,no significant difference was found in gender.All types of malocclusion symptoms were analysed,Deep overbite prevalence rate is highest(55.39%), followed by deep overjet(24.31%),dental crowding(21.25%),cross-bite(12.03%)and open-bite(7.22%),. 35 percent of the patients with more than two kinds of malocclusion. Conclusion： The prevalence of malocclusion in primary dentition and types of malocclusion symptoms in the area of Shanghai were obviously changed than before. A series of secorresponding preventive measures needs to formulate to prevent the occurrence and development of malocclusion in primary dentition.

The incidence of the fourth molar in the crowd is low, especially in bilateral maxillary. However,there are some complications coming with the fourth molar. Here we reported a case of bilateral maxillary fourth molar to make a detailed discussion about the etiology, diagnosis, prognosis and treatment of this disease.

How to shorten orthodontic time has been a topic of concern for clinicians. The previous researches found corticotomy can effectively accelerate orthodontic treatment. Based on the regional acceleratory phenomenon (RAP), the technology evolved in the past few decades. Then, a technique called Periodontally Accelerated Osteogenic Orthodontics (PAOO) was developed from corticotomy. PAOO can reduce 1/3 to 1/4 traditional treatment time for patients, improve and strengthen the periodontal tissue, increase bone coverage, reduce root resorption and the relapse rate. This paper provides a comprehensive overview of the history of the corticotomy development, the different mechanisms of corticotomy accelerating tooth movement from the traditional orthodontics, as well as related clinical and experimental studies.　

Implant surface treatment is an important factor in the formation of osseointegration. It plays a key role in raising the success rate of implantation. Generally, the implant surface treatment is to make a rough surface to improve the implant osseointegration and biocompatibility. This review summarized various processing technologies of the implant surface treatment, such as mechanical processing method, chemical method and biological treatment, etc. And it also discussed the effect of these technologies on osseintergration

Coronectomy of the impacted high-risk mandibular third molar is a technique that could reduce the incidence of inferior alveolar nerve injury. Many studies have shown the practicability of coronectomy and its lower incidence of complications. In this paper, we discuss the technique as an overview and the management of common complications.

Abstract: Cone beam computed tomography with its 3D reconstruction imaging, high resolution and many other advantages，has been widely used in oral clinical aspects, which simplified and improved the clinical diagnosis and treatment. This paper reviews the fundamentals of CBCT and presents the application of this imaging system in the latest endodontic practice.