牙齿几何外形和模型底座厚度对隐形矫治器厚度的影响

目的研究牙齿几何外形和模型底座厚度对热成型隐形矫治器厚度的影响。方法层析扫描标准上颌模型,形成数字图像,通过数字化三维图像处理,激光快速成型输出底座厚度分别为0、1、2、3、4、5、6、7、8、9、10 mm的树脂模型共11副,在每个树脂模型上通过热压膜成型制作10副矫治器,标记每副矫治器上14个牙位的唇颊面和舌腭面牙冠面轴点,使用千分尺测量牙冠面轴点处矫治器的膜片厚度,比较热压膜成型后不同牙位上隐形矫治器的厚度,分析厚度分布规律。结果底座厚度为0 mm时,隐形矫治器中切牙到第二磨牙唇颊面厚度从0.398 mm均匀递增到0.504 mm,坐标图表现为均匀递增的直线,膜片厚度随牙位变化的直线公式为y=0.019x+0.379,拟合度和相关性良好。尖牙腭面膜片厚度最大,第一磨牙腭面膜片厚度大于第二前磨牙,表现为S形曲线。不同底座厚度的树脂模型上热成型的矫治器唇颊面和舌腭面膜片厚度随牙位变化的规律基本相同。隐形矫治器唇颊面和舌腭面的膜片厚度随模型底座厚度的增加呈递减趋势。结论隐形矫治器唇颊面厚度从前牙到后牙均匀递增;矫治器腭面厚度以尖牙最厚,分布无明显规律。模型底座厚度对隐形矫治器厚度有影响。

Influence of geometrical shape of teeth on the thickness of invisible aligners

Objective Analyse the influence of geometrical shape of teeth on the thickness of invisible aligners by comparing the thickness of different positions after thermoform. Methods Standard maxillary model was chromatographi- cally scaned to obtain STL model with different base heights by digital graphic processing techniqueand rapid prototyping technology. 10 aligners on every SLA model were made by thermoforming technique, then the thickness was measured with micrometer and the thickness distribution was analyzed. Results The thickness from central incisor to second mo- lars ranged from 0. 398 mm to 0.504 mm, which showed an increasing line in diagram, and the formula of line was y = 0. 019x ＋0. 379. The palatal surface of canine was thickest, while the first molar was thicker than second molar. Con- clusion The thickness of labial surface increases steadily from anterior teeth to posterior teeth. The thickness of palatal surface is prominent at canine position and the distribution of thickness has no regular pattern.