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目的：为了更准确地进行上下颌牙列数字化模型的咬合状况定量分析，对分别用口内扫描和模型扫描方法获取的三维数字化模型的咬合接触指标进行定量分析及对比研究。方法：用三维激光扫描仪对具有完整牙列并且咬合正常的健康志愿者5人进行口内扫描，分别获取单侧1个牙位（第一磨牙）、2个牙位（第二前磨牙及第一磨牙）、3个牙位（两个前磨牙及第一磨牙）及其邻牙的上下颌数字化模型，运用专用计算机分析软件进行牙尖交错位时咬合接触状况的三维测量及分析，然后用加成型硅橡胶采取上下颌牙列实物印模并灌制超硬石膏模型，应用专用定位装置将上下颌模型在牙尖交错位对合并固定，用激光扫描仪扫描上下颌模型，形成三维数字化牙列模型。对用口内和模型扫描方法分别获得的数字化模型的下颌第一磨牙进行咬合接触紧密程度（上下颌咬合面平均间距）、咬合接触面积及牙尖斜度等咬合相关指标的定量分析和比较。应用配对t检验方法比较两种扫描方法获得数字化模型的各项指标的统计学差异（α=0.05），重复测量计算牙尖斜度的组内相关系数（intraclass correlation coefficient，ICC）进行一致性检验。结果：口内扫描1~3个牙位时获得的上下颌第一磨牙咬合面平均间距分别比模型扫描的小0.134 mm、0.177 mm和0.207 mm，差异有统计学意义（P<0.5）。两种扫描方法的标准差之差分别为0.02 mm、0.02 mm和0.03 mm，差距较小。口内扫描1~3个牙位时下颌第一磨牙的咬合接触面积分别比模型扫描的大8.65 mm2、10.28 mm2和11.46 mm2，差异有统计学意义（P<0.5）。两种扫描方法的标准差之差为0.43 mm2、1.55 mm2和2.04 mm2，1个牙位扫描后的标准差要明显小于2个牙位和3个牙位时。两种扫描方法进行牙尖斜度测量时，ICC大于0.90，两种方法的牙尖斜度测量值差异无统计学意义（P>0.5）。结论：口内扫描测得的咬合面平均间距小于模型扫描测得的，口内扫描测得的咬合接触面积大于模型扫描测得的，说明口内扫描反映的咬合接触程度更为紧密。口内扫描测量咬合接触面积的均值标准差与测量牙位数量相关。两种方法测量得到的牙尖斜度差异没有统计学意义，说明口内扫描进行牙齿形态学指标测量时与模型扫描无明显差别，有望今后替代模型扫描。
OBJECTIVE: To quantitatively analyze the occlusion status of digital model of maxillary and mandibular dentition, quantitative analysis and comparative study of occlusal contact index of three-dimensional digital model obtained by oral scanning and model scanning were performed respectively. Methods: Five healthy volunteers with intact dentition and normal occlusion were scanned with a three-dimensional laser scanner. One unilateral tooth (first molar), two teeth (second premolar and A molar), three teeth (two premolar and first molar) and its adjacent teeth digital model of the upper and lower jaw, the use of special computer software for three-dimensional measurement and analysis of occlusal contact state at the cusp position, and then use Addition-type silicone rubber to take the mandibular dentition in-line physical model and filling the superhard plaster model, the use of special positioning device on the mandibular model at the cusp of staggered position on the merger fixed with a laser scanner to scan the upper and lower jaw model to form a three-dimensional digital dentition model. The quantitative analysis and comparison of occlusal related indexes such as occlusal contact degree (average distance between maxilla and occlusal surface), occlusal contact area and cusp inclination of the mandibular first molar obtained by the intraoral and model scanning methods respectively. The paired t-test method was used to compare the statistical differences between the two methods (α = 0.05) and the intraclass correlation coefficient (ICC) of the cusp inclination for repeated measurements. . Results: The average interplanar spacing of the first mandibular molar obtained from 1 to 3 dental positions was 0.134 mm, 0.177 mm and 0.207 mm lower than the model scan, respectively, with a significant difference (P & lt; 0.5). The difference between the standard deviations of the two scanning methods is 0.02 mm, 0.02 mm and 0.03 mm respectively, with a small difference. The interfacial contact area of mandibular first molars was 8.65 mm2, 10.28 mm2 and 11.46 mm2 larger than that of model scans when the mouth was scanned with 1-3 dental sites. The difference was statistically significant (P & lt; 0.5). The difference between the standard deviations of the two scanning methods was 0.43 mm2, 1.55 mm2 and 2.04 mm2, and the standard deviation after one tooth scan was significantly less than two and three. ICC was greater than 0.90 for both cusp inclination measurements, and there was no significant difference in cusp inclination between the two methods (P & gt; 0.5). Conclusion: The average distance between the occlusal planes measured by the intraoral scan is less than that measured by the model scan. The measured occlusal contact area measured by the intraoral scan is larger than that measured by the model scan, indicating that the intraoral scan reflects the occlusal contact more closely. The mean standard deviation of the osseo-contact area measured by the intraoral scan correlates with the number of teeth measured. There was no statistical difference in the cusp inclination measured by the two methods, which indicated that there was no significant difference between the intraoral scan and the model scan in the measurement of dental morphological index. It is expected to replace the model scan in the future.