Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, No. 56, Lingyuan west road, Guangzhou, 510060, China.
KTJ Dental Group, Shenzhen, China.
BMC Oral Health. 2021 Dec 7;21(1):623. doi: 10.1186/s12903-021-01986-2.
The accuracy of digital impressions for fully edentulous cases is currently insufficient for routinely clinical application. To overcome the challenge, a modified scan body was introduced, which demonstrated satisfactory accuracy in vitro. The aim of this study was to evaluate the accuracy of digital impressions using the modified scan bodies with extensional structure versus scan bodies without extensional structure in mandible with two implants in beagle dogs.
The unilateral mandibular second premolar to second molar were extracted in four beagle dogs. Twelve weeks later, two implants were placed. Five repeated digital impressions were performed with an intraoral scanner on each dog using each of the two different scan bodies: Group I-scan body without extensional structure (SB); Group II-scan body with extensional structure (SBE). The scans were exported to Standard Tessellation Language (STL) files to serve as test data. The dogs were sacrificed and the dissected mandibles were digitalized with a lab scanner to provide reference data. Linear and angular deviations were calculated in an inspection software for accuracy assessment. Statistical analysis was performed with two-way ANOVA. The level of significance was set at α = 0.05.
For trueness assessment, the mean of absolute linear/angular deviations were 119.53 μm/0.75 degrees in Group I and 68.89 μm/0.36 degrees in Group II. SBE was more accurate than SB regarding both linear (p = 0.008) and angular (p = 0.049) deviations. For precision assessment, the mean of absolute linear/angular deviations were 63.01 μm/0.47 degrees in Group I and 38.38 μm/0.24 degrees in Group II. No significant difference was found.
The application of SBE significantly improved the trueness of digital impressions in mandible with two implants compared to SB. No significant difference was found in terms of precision.
目前，全口无牙颌病例的数字化印模精度还不足以常规应用于临床。为了克服这一挑战，引入了一种改良的扫描体，其在体外表现出令人满意的精度。本研究旨在评估带有扩展结构的改良扫描体与无扩展结构的扫描体在犬下颌植入两颗种植体时的数字化印模精度。
在四只比格犬中，单侧下颌第二前磨牙至第二磨牙被拔除。12 周后，植入两颗种植体。每只犬使用两种不同的扫描体各进行 5 次重复的口内扫描仪数字化印模：I 组-无扩展结构的扫描体（SB）；II 组-带有扩展结构的扫描体（SBE）。扫描结果以标准 tessellation language（STL）文件导出，作为测试数据。犬被处死，解剖下颌用实验室扫描仪进行数字化，作为参考数据。在检查软件中计算线性和角度偏差，以评估准确性。采用双向方差分析进行统计学分析。显著性水平设为α=0.05。
在准确性评估方面，I 组的平均绝对线性/角度偏差为 119.53μm/0.75 度，II 组为 68.89μm/0.36 度。SBE 在线性（p=0.008）和角度（p=0.049）偏差方面均比 SB 更准确。在精密度评估方面，I 组的平均绝对线性/角度偏差为 63.01μm/0.47 度，II 组为 38.38μm/0.24 度。两组之间无显著差异。
与 SB 相比，SBE 的应用显著提高了下颌植入两颗种植体时数字化印模的准确性。在精密度方面，两组之间无显著差异。
