中切牙金属烤瓷冠牙体预备的探索性实验

中切牙金属烤瓷冠牙体预备的探索性实验沈燕青;胡赛;孔卓玲;傅柏平【摘要】Objective] Aftermaxillary central incisors were normatively prepared for metal ceramic crowns by undergraduate stomatology students in the pre -clinical practical skills training , the tooth preparation and the thickness of temporary crowns were measured for the measurement of the reduction of tooth preparation and calculation of the mesio -distal convergence angle of the tooth preparation .[Method] Eleven students took part in the investigation .After standard artificial teeth were set in the head simulators ,heavy body silicon impression materials were homogeneously kneaded to cover two maxillary central incisors and a maxillary lateral incisor .Each student was asked to normatively prepare a maxillary central incisor ,and to make a tempo-rary crown via silicon impression . After the tooth preparation and the thickness of the temporary crowns were measured by vernier calipers ,the medians ,and lower ,upper quartiles(P25 ,P75)were obtained and the mesio -distal convergence angles were calculated via inverse trigonometricfunction .[Result]The incisal reductions were appropriate ,the facial and the linqual re-ductions ,and the gingival margin were not enough prepared . The degrees of the mesio -distal convergence angle were toolarge .[Conclusion]Students easily learnedto prepare the incisalreductions ,however ,they were not easily to prepare the depth (the thickness) of the tooth reducitons and the mesio -distal convergenceangle .This exploratory experiment can be used to judge the students’ ability of tooth preparation .%目的：口腔医学本科生临床前技能培训实验中，对上颌中切牙金属烤瓷冠标准化预备后的基牙，进行预备量的测量，并计算近远中轴向聚合角。

方法：本班学生总数11人，要求学生在教学头模上先制作硅橡胶印模，再标准化预备1颗右上颌中切牙（人工牙），然后借助硅橡胶印模制作预备牙齿的临时冠，使用游标卡尺间接测量临时冠各轴面的预备厚度，记录并求得平均值数据；通过在牙备后的基牙各轴面及边缘嵴上选取合适的测量点，运用反三角函数计算出近远中轴向聚合角，记录最大值、最小值，并求得上四分位数（P75）、中位数及下四分位数（P25）。

结果：牙体预备量的测量值：切缘预备量恰当；唇面、舌面、颈缘预备量不足；近远中邻面轴向聚合角过大。

结论：学生一般较易掌握牙齿切端的磨除，不易掌握牙齿深度（厚度）的磨除量和轴向聚合角的大小。

该测量方法可作为本科生临床前技能培训中评判标准化牙体预备能力的一项指标。

【期刊名称】《浙江医学教育》【年(卷),期】2015(000)006【总页数】4页(P17-20)【关键词】标准化预备;聚合角;测量【作者】沈燕青;胡赛;孔卓玲;傅柏平【作者单位】浙江大学医学院附属口腔医院，浙江杭州 310006;浙江大学口腔医学院，浙江杭州 310058;浙江大学口腔医学院，浙江杭州 310058;浙江大学医学院附属口腔医院，浙江杭州 310006【正文语种】中文【中图分类】G642.0Abstract :[Objective] Aftermaxillary central incisors were normatively prepared for metal ceramic crowns by undergraduate stomatology students in the pre-clinical practical skills training, the tooth preparation and the thickness of temporary crowns were measured for the measurement of the reduction of tooth preparation and calculation of the mesio-distal convergence angle of the tooth preparation. [Method] Eleven students took part in the investigation. After standard artificial teeth were set in the head simulators, heavy body silicon impression materials were homogeneously kneaded to cover two maxillary central incisors and a maxillary lateral incisor. Each student was asked to normatively prepare a maxillary central incisor, and to make a temporary crown via silicon impression. After the tooth preparation and the thickness of the temporary crowns were measured by vernier calipers, the medians,and lower ,upper quartiles(P25, P75)were obtained and the mesio-distal convergence angles were calculated via inverse trigonometric function.[Result]The incisal reductions were appropriate, the facial and the linqual reductions，and the gingival margin were not enough prepared. The degrees of the mesio-distal convergence angle were too large. [Conclusion]Students easily learnedto prepare the incisalreductions, however, they were not easily to prepare the depth (the thickness) of the tooth reducitons and the mesio-distal convergence angle. This exploratory experiment can be used to judge the students’ ability of tooth preparation.Key words: tooth preparation; convergence angle; measurement牙齿的标准化预备, 在固定义齿的临床修复中尤为重要, 预备体的质量直接关系到修复体的质量及其保存时间[1]。

其中牙体的预备量以及基牙轴面所形成的聚合角，是两项衡量牙体预备合格与否的重要指标。

它不仅对义齿的固位有着至关重要的作用, 同时还直接关系到患牙牙体组织的保存及修复体的预后。

牙齿标准化预备技能的培训，在初次接触临床的本科生教学中，占据极为重要的位置。

基于此, 本实验对学生实验室预备的基牙模型进行了相应的测量和分析，给予牙备质量以定量的分析。

1.1 实验所用材料和器械仿真头模，口腔检查盘，吸唾器，各类车针，铝制托盘，加成型硅橡胶印模材料，“速凝”临时冠桥材料，游标卡尺。

1.2 实验一临时冠厚度的测量1.2.1 牙备前硅橡胶导模的制取按1:1混合加成型硅橡胶重体，至少覆盖相邻2牙位，以保证就位顺利。

1.2.2 上颌中切牙的标准化预备[2]切端：预备量1.5～2.0mm，作1.5mm引导沟，上前牙切缘与牙体长轴呈45°面向腭侧的小斜面；唇面：预备量1.2～1.5mm(欧美标准)，分切1/2和颈1/2两个平面磨，颈1/2与长轴一致，决定冠的就位道，作1.0mm的引导沟；邻面：去除邻面倒凹，形成2～5°聚合角，勿伤邻牙，与唇舌面颈缘均匀圆滑过渡，具体预备量还应根据临床修复体瓷覆盖范围的设计不同而不同，约1.0～1.5mm；舌面：以瓷覆盖舌面为例，预备量1.0～1.5mm，中部形成0.7～0.8mm引导窝，保持舌窝形态；肩台：以360°有瓷覆盖肩台为例，排龈后，预备形成一周宽1.0mm深凹槽型或直角肩台型，在不损伤附着龈的前提下，位置达龈下0.5mm；精修：唇面切1/4～1/3向舌侧内收10°～15°，去除尖锐边缘，磨除各面余量，检查咬合关系。