【摘要】 背景:在口腔正畸的治疗过程中,经常会遇到托槽脱落的情况。脱落的托槽是否能被再次利用,再次利用前需对托槽进行何种处理,其粘结强度是否会受到影响,这是正畸医师临床上非常关心的问题。目的:检测旧金属托槽再次粘结的抗剪切强度,并对重新粘结前的底板处理方法进行对比。设计:分组对照研究。单位:青岛大学医学院附属医院口腔正畸科与北京大学口腔医学院材料实验室。对象:实验所用离体牙来源于青岛大学医学院附属医院口腔外科,为口腔正畸需要而拔除的双尖牙,牙冠表面釉质完好,无龋坏、无裂纹、非四环素牙、非氟斑牙。被拔牙患者年龄11~19岁,男女各半;患者均同意提供所拔除牙用于实验。方法:实验于2005-12在北京大学口腔医学院完成。选正畸需要而拔除的离体双尖牙30颗,首次粘结托槽24h后去除托槽,以此为实验标本,随机分为3组,每组10颗牙齿。第1组粘结新托槽;第2,3组粘结旧托槽,其中第2组托槽底板的残余粘结剂通过火烧去掉,第3组为保留底板槽沟内的粘结剂而将底板刮平。实验所用托槽为浙江orsu公司生产的整铸方丝弓托槽。粘结托槽24h后,应用日本岛津公司所生产(Autogragh,Shimadzu,日本)的材料力学实验机分别测定以上三组托槽的剪切强度。并对每一牙面上的粘结剂残留量进行统计。主要观察指标:旧金属托槽再次粘结的抗剪切强度;粘结剂残留量。结果:①抗剪切强度:新托槽组、烧过的旧托槽组、保留槽沟底胶组分别为(10.094±3.1589),(10.266±2.4060),(8.898±1.3659)MPa,3组比较,差异无显著性意义(P>0.05)。②粘结剂残留量:新托槽组、烧过的旧托槽组、保留槽沟底胶组托槽脱落后分别为51.7%,58.3%,35.0%,其中后两组比较,差异有显著性意义。结论:旧托槽的重复利用仍能达到满意的粘结强度;新旧粘合剂之间可能存在着较强的化学结合。更多还原

【Abstract】 BACKGROUND: Bracket dropping is often seen in clinic. Can these shed brackets be used again; what should be done to treat these brackets; is the bond strength of these recycled brackets different from those new ones, these questions are often concerned by orthodontists in their clinic and are the purpose of our study as well. OBJECTIVE: To evaluate the shear bond strength and compare two base-cure methods of recycled brackets. DESIGN: Grouping control study. SITTING: Department of Orthodontics, the Affiliated Hospital of Medical College, Qingdao University; Department of Materials, Dental School, Beijing University. MATERIALS: The teeth were collected from Oral Surgery, the Affiliated Hospital of Medical College, Qingdao University. The age was from 11 to 19 years. The gender was half male and half female. Intact enamel of the crown was required, but decayed, fracture, tetracycline pigmentation teeth or fluorosis teeth were excluded. Patients provided the confirmed consent for this experiment. METHODS: The experiment was carried out in Stomatology College of Peaking University in December 2005. Thirty ex vivo teeth were selected randomly from those prepared enamel surfaces, used as sample for rebounding. The edgewise brackets of swallow-tailed brackets were bonded on each tooth and rebonded after 24 hours. The teeth were cleaned and divided randomly into 3 groups. There were 10 teeth in each group. Group 1 was bonded with new brackets; group 2 with recycled brackets whose adhesive remnant were burned and got rid of; group 3 with recycled brackets whose adhesive remnant in the groove of the base were stored. Bracket was provided by Standard edgewise, Orsu Company, Hangzhou, China. After 24 hours, the shear bond strength was tested with material testing machine (Autogragh, Shimadzu, Japan). Adhesive remnant index (ARI) was added up. MAIN OUTCOME MEASURES: Shear strength of old metal bracket after rebonding and adhesive remnant. RESULTS: ① Shear bond strength: The shear bond strengths were (10.094±3.158 9) in group 1, (10.266±2.406 0) in group 2 and (8.898±1.365 9) in group 3. There were no statistically significant differences among the three groups (P > 0.05). ② ARI scores: ARI scores were 51.7%, 58.3% and 35.0% in the three groups, respectively. There were statistically significant differences between group 2 and 3. CONCLUSION: In vitro study indicates that the recycled metal brackets can reach good bond strength and that maybe there is chemical bond between new and old adhesive.更多还原