3种不同材料三维模型牙临床应用特点比较

目的:应用口腔数字印模仪结合Mimics 19.0软件,分析3种不同材料三维模型牙的精度,并结合问卷调查比较其理化性能、经济学特点和临床应用特点。方法:对开展自体牙移植技术的医师进行问卷调查,了解其对不同供牙模型材料的认识;然后就各模型牙的材料使用性能、工艺性能、经济性、环境协调性等特点进行比较分析。搜集完整拔除的第三磨牙20颗,根据患者术前CBCT数据分别制作聚乳酸、光敏树脂、钴铬合金材料的三维牙模型,使用口腔数字印模仪扫描离体牙及各种材料的模型牙,数据用Mimics 19.0软件进行最佳拟合对齐和三维分析,对所得均方根(root mean square,RMS)误差值进行统计分析,明确精度差别。采用SPSS 22.0软件包对数据进行统计学分析。结果:问卷结果显示,95.2%的口腔医师认为供牙模型在自体牙移植术中用处很大且经常使用,90.5%的口腔医师认为材料成本以及无毒无公害最为重要。常用的3种不同材料的模型牙与第三磨牙的RMS值无统计学差异(P>0.05)。3种材料加工技术成熟、工艺性能良好、使用性能较好,其中聚乳酸价格低廉,兼具生物降解性,操作风险较低;光敏树脂价格中等,但其制造过程可能会产生毒性物质且操作风险较高;钴铬合金耐高温高压,但打印周期较长,成本较高。结论:聚乳酸、光敏树脂、钴铬合金3种材料的模型牙三维精度无显著差异,但综合3种材料模型牙的各种特点,聚乳酸的性价比最高,值得临床推广应用。

Autotransplantation of a premolar to the maxillary anterior region in young children- how long should the donor root be? A case report

Autotransplantation of premolars to anterior region after incisor loss due to trauma is accepted as the best restoration procedure with very long follow-ups. There are two main protocols: Premolars with only two thirds of the root or premolars with complete root development. Premolars with two thirds of the root completed remain vital and show complete pulp obliteration while premolars with closed apex require root canal treatment. The problem arises when the child is very young and the root of the donor premolar is developed for only one third. This case report describes the outcome of an autotransplantation of a lower first premolar with only a third of developed root to the anterior region. The donor tooth was extracted with his follicle and placed instead of tooth No. 21. For the first month esthetics was restored with a glass-fibers ribbon attached to tooth No. 11 and composite material. After a month, the crown erupted and was reshaped to mimic an incisor with composite. Orthodontic movement was performed after 5 mo, in order to alleviate the gingival contour. The final restoration was performed after 15 mo. Follow up showed full root development with normal mobility, continuous periodontal ligament and complete pulp obliteration. A multidisciplinary approach and meticulous preparation are necessary for a positive result in autotransplantation of premolars with only a third of root development to the anterior region and this case report show that this method can be performed in very young children.

数字化设计与3D打印在自体牙移植术的应用

目的探讨术前数字化设计结合3D打印供体牙模型及受区牙槽窝模型辅助自体牙移植术的效果。方法收集12例因牙折或牙槽骨广泛吸收而无法保留的第一或第二磨牙,将其锥形束CT数据导入Mim⁃ics数字化设计软件中,选取匹配度最高的第三磨牙作为供体牙,3D打印出供体牙及受区牙槽窝模型进行术前模拟移植术。术中在供体牙模型引导下进行受区牙槽窝及供体牙的预备,将供体牙移植于受区。术后3、6、12个月复查锥形束CT评估骨重建及牙周膜状况。结果12例患者均选择根尖孔已完全闭合的第三磨牙作为供体牙即刻移植于磨牙区。7例受区牙槽窝术前存在感染,其中1例因受区患牙感染致牙槽骨广泛吸收。12例手术短期恢复良好,均完成12个月以上随访,其中11例移植牙成功,能正常行使咀嚼功能,1例在术后14个月时出现牙根吸收。结论数字化设计结合3D打印技术能够辅助匹配最合适的供体牙,术前完成受区牙槽窝精准预备,减少供体牙在体外的暴露时间和移植到牙槽窝内的试放次数,有助于自体牙移植成功。