目的: 通过虚拟数字模型实验比较动态咬合记录法(patient-specific motion, PSM)和平均值数字牙合架法设计前牙种植单冠修复体切导的正确度。方法: 招募12名牙列完整、有稳定切导的健康受试者, 口内扫描获得受试者牙列模型, 并采集两种动态咬合记录:(1)仅包括前伸运动; (2)包括前伸运动及侧前伸运动。加高原始模型上中切牙参与前伸引导的部分舌面作为参考模型; 虚拟拔除单个上中切牙, 虚拟种植获得上颌工作模型。在修复体设计软件中使用复制功能进行种植单冠形态设计, 使用不同数字化方法设计切导:对照组为平均值数字牙合架法, 试验组为仅包括前伸运动的动态咬合记录法(PSM1)和包括前伸运动和侧前伸运动的动态咬合记录法(PSM2)。通过逆向工程软件分析比较修复体切导形态与原始切导形态的三维偏差, 评价指标包括代表高牙合程度的正值平均值、正面积比、最大值, 代表低牙合程度的负值平均值、负面积比、最小值, 以及代表整体偏差程度的均方根。结果: 数据采用中位数(四分位距)表示。PSM2组的正值平均值、正面积比、负值平均值小于对照组[8.0(18.8) μm vs. 37.5(47.5) μm; 0 vs. 7.2%(38.1%); -109.0(63.8) μm vs.-66.5(64.5) μm], 负面积比大于对照组[52.9%(47.8%) vs. 17.3%(45.3%)], 差异均具有统计学意义(P＜0.05);PSM1组的正面积比[0.1%(7.0%)]和负值平均值[-97.0(61.5) μm]均小于对照组, 负面积比[40.7%(39.2%)]大于对照组, 差异具有统计学意义(P＜0.05);PSM1组的正值平均值[20.0(42.0) μm]和正面积比均大于PSM2组, 差异具有统计学意义(P＜0.05)。结论: 设计前牙种植单冠修复体切导时, 相较于平均值数字牙合架法和仅包括前伸运动的动态咬合记录法, 包括前伸运动和侧前伸运动的动态咬合记录法更有利于减少修复体的咬合干扰, 提高咬合适合性。

Objective: To compare the trueness of incisal guidance of implant-supported single crowns designed by patient-specific motion (PSM) with that designed by average-value virtual articulator (AVA). Methods: The study had recruited 12 participants with complete dentition and stable incisal guidance. An intraoral scanner was used to scan digital casts and record two types of patient-specific motion (data only including protrusive movement, and data including protrusive movement and lateral protrusive movement). The lingual surfaces of the maxillary incisors which guided the protrusive movement was selected and elevated to create a reference cast. A maxillary central incisor of original casts was vir-tually extracted and implanted to generate a working cast. The Dental system software program was used to design implant-supported single crowns with the anatomical coping design method. The incisal guidance was designed by different methods. The incisal guidance in control group was designed by the average-value virtual articulator. The incisal guidance in experiment groups was designed by the patient-specific motion only including protrusive movement (PSM1) and with the patient-specific motion including protrusive movement and lateral protrusive movement (PSM2). The incisal guidance of prosthesis designed by these 3 methods were compared with the original incisal guidance in Geomagic Control 2015 (3DSystem, America). The measurements included: Average of positive values, ratio of positive area and maximum value reflecting supra-occlusion; average of negative values, ratio of negative area and minimum value reflecting over-correction; and root mean square reflecting overall deviation. Results: Statistical data were collected using the median (interquartile range) method. The average of positive values, ratio of positive area and average of negative values of the PSM2 group were smaller than those of the control group [8.0 (18.8) μm vs. 37.5 (47.5) μm; 0 vs. 7.2% (38.1%); -109.0 (63.8) μm vs.-66.5 (64.5) μm], and the ratio of negative area of PSM2 group was larger than those of the control group [52.9% (47.8%) vs. 17.3% (45.3%)], with significant differences (P all < 0.05). The ratio of positive area [0.1% (7.0%)] and average of negative values [-97.0 (61.5) μm] of PSM1 group, were smaller than those of the control group, and the ratio of negative area [40.7% (39.2%)] of the PSM1 group was larger than that of the control group, with significant differences (P < 0.05). The average of positive values [20.0 (42.0) μm] and ratio of positive area of PSM1 group was larger than that of the PSM2 group with significant differences (P < 0.05). Conclusion: To establish the incisor guidance of implant-supported single crowns, compared with the average-value virtual articulator and the patient-specific motion only including protrusive movement, the patient-specific motion including protrusive movement and lateral protrusive movement is more conducive to reducing the protrusive interference of prosthesis and improving the occlusal fit.