State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
J Prosthodont. 2022 Aug;31(7):593-600. doi: 10.1111/jopr.13456. Epub 2021 Dec 15.
To evaluate the accuracy (trueness and precision) of reduction depths of guided veneer preparation assisted by four tooth preparation guides.
Fifty resin artificial teeth were randomly divided into five groups (n = 10): a freehand group (F), silicone guide group (S), thermoplastic guide group (T), 3D printed uniform guide group (D), and 3D printed auto-stop guide group (A). A preparation for a window veneer on the maxillary right central incisor was performed by two surgeons who used tooth preparation guides for assistance. The maxillary right central incisors were scanned before and after the preparation. The reduction depths were measured in the cervical, middle, and incisal thirds of the prepared surface, and depth maps were created using Geomagic Control X software. The accuracy of the reduction depths at each third was evaluated using both trueness and precision values. The trueness of the reduction depths was determined by calculating the mean absolute differences (MADs) compared to the planning depth, and precision was determined by the standard deviation (SD). The collected data were statistically analyzed using one-way ANOVA and the least significant difference test (α = 0.05).
The MAD ± SD values of the reduction depths in the cervical-third region in groups F, S, T, D, and A were 0.19 ± 0.04, 0.12 ± 0.03, 0.09 ± 0.02, 0.07 ± 0.02, and 0.05 ± 0.01 mm, respectively. In the middle-third region, the MAD ± SD values of groups F-A were 0.19 ± 0.05, 0.13 ± 0.02, 0.09 ± 0.01, 0.06 ± 0.01, and 0.05 ± 0.01 mm. In the incisal-third region, the MAD ± SD values were 0.27 ± 0.05, 0.16 ± 0.04, 0.11 ± 0.03, 0.07 ± 0.01, and 0.05 ± 0.01 mm, respectively. Significant differences in trueness and precision values were found across different groups (F = 45.378, p = 0.000), where group F showed higher MADs than the other 4 groups (p = 0.000), and the highest MADs were detected in group S among the 4 groups in all regions (p = 0.000). Group T showed significantly higher MADs than groups D (P = 0.008) and A (p = 0.001), except in the cervical-third region, where no significant difference was observed between groups T and D (p = 0.077). There was no significant difference between groups D and A (p = 0.148). The deviation map showed significant differences among groups (F = 15.963, p = 0.000), group T presented less deviation than group F (p = 0.000) and group S (p = 0.027) and showed more deviation than group A (p = 0.007).
Tooth preparation guides provided more accuracy for veneer preparation than freehand preparation. Among the 4 guides, the 3D printed auto-stop guide presented the lowest absolute difference (0.05 mm) and the silicone guide showed the highest absolute difference of preparation (0.12-0.16 mm).
评估四种牙预备导板辅助下的贴面预备深度的准确性（准确性和精密度）。
将 50 颗树脂人工牙随机分为五组（n=10）：自由手组（F）、硅橡胶导板组（S）、热塑性导板组（T）、3D 打印均匀导板组（D）和 3D 打印自动停止导板组（A）。两名外科医生使用牙预备导板协助进行上颌右中切牙的窗式贴面预备。预备前后扫描上颌右中切牙。在预备表面的颈、中、切三分之一处测量减少深度，并使用 Geomagic Control X 软件创建深度图。使用准确度和精密度值评估各三分之一的减少深度的准确性。通过计算与规划深度的平均绝对差值（MAD）来确定减少深度的准确度，通过标准偏差（SD）来确定精密度。使用单向方差分析和最小显著差异检验（α=0.05）对收集的数据进行统计学分析。
F、S、T、D 和 A 组颈三分之一区减少深度的 MAD ± SD 值分别为 0.19 ± 0.04、0.12 ± 0.03、0.09 ± 0.02、0.07 ± 0.02 和 0.05 ± 0.01mm。在中三分之一区，F-A 组的 MAD ± SD 值分别为 0.19 ± 0.05、0.13 ± 0.02、0.09 ± 0.01、0.06 ± 0.01 和 0.05 ± 0.01mm。在切三分之一区，MAD ± SD 值分别为 0.27 ± 0.05、0.16 ± 0.04、0.11 ± 0.03、0.07 ± 0.01 和 0.05 ± 0.01mm。不同组之间的准确度和精密度值存在显著差异（F=45.378，p=0.000），F 组的 MAD 值高于其他 4 组（p=0.000），且 4 组中 S 组在所有区域的 MAD 值均最高（p=0.000）。T 组的 MAD 值显著高于 D（P=0.008）和 A 组（p=0.001），但在颈三分之一区，T 组和 D 组之间无显著差异（p=0.077）。D 组和 A 组之间无显著差异（p=0.148）。组间偏差图显示出显著差异（F=15.963，p=0.000），T 组的偏差小于 F 组（p=0.000）和 S 组（p=0.027），但大于 A 组（p=0.007）。
牙预备导板比徒手预备能提供更准确的贴面预备。在这 4 种导板中，3D 打印自动停止导板的绝对差值最低（0.05mm），硅橡胶导板的绝对差值最大（0.12-0.16mm）。
