Objective To analyze the clinical effect of both micro-implant anchorage and selective extracting maxillary first molar to correct the failure of orthodontics.Methods From January 2006 to June 2012,24 cases who suffered from failure of orthodontics were treated in this department.To all patients,bilateral maxillary first molars were extracted,and micro-implant anchorage were planted into maxilla from buccal alveolar ridge to correct malocclusion acting as anchorages.Lateral cephalometric radiographs,intraoral photograph and facial photograph of every patient were taken before and after treatments; Their over bite and overjet molar relationship and incisors retraction were compared before and after treatments.Methods All the micro implant anchorages were sucessfuly implanted except two patients who experienced second operation owing to luxation of three implants.All the molars were strengthed and the profile improved along with their normal over bite and overjet.Conclusions The treatment of using micro-implant anchorage and selective extracting maxillary first molar is an ideal option of second orthodontics.Unconventional tooth extraction is used in this treatment.Micro implant anchorages are stable,acceptable and effective in clinical application.

Medicine is a practical application subject,so medical students should conduct numerous clinical practice to improve operation skills and clinical diagnosis ability The ability of clinical practice is one of most important indicators to evaluate medical education quality.In recent years,medical students have been affected by many kinds of adverse factors,such as new doctor-patient relationship,the medical reform and employment pressure and so on.All these adverse factors will bring a great challenge to the dental clinical teaching.In the new medical situation we need urgently to solve the problems to guide students to improve clinical practice ability and cultivate qualified dental professionals

It is difficult to avoid the shedding of brackets during orthodontic treatment, which may not only affect the orthodontic therapeutic effect but also prolong the orthodontic treatment duration. Sodium hypochlorite is a commonly used root canal irrigation agent in oral medicine and is seldom used in orthodontic treatment. Sodium hypochlorite on the enamel surface can strengthen the effect of etching by deproteinization to improve adhesion, which could reduce the probability of bracket shedding during orthodontic treatment. Therefore, this article reviews the effects of sodium hypochlorite on enamel.