Basaki Kinga, Alkumru Hasan, De Souza Grace, Finer Yoav
Int J Oral Maxillofac Implants. 2017 July/August;32(4):792–799. doi: 10.11607/jomi.5431. Epub 2017 Jun 14.
To assess the three-dimensional (3D) accuracy and clinical acceptability of implant definitive casts fabricated using a digital impression approach and to compare the results with those of a conventional impression method in a partially edentulous condition.
A mandibular reference model was fabricated with implants in the first premolar and molar positions to simulate a patient with bilateral posterior edentulism. Ten implant-level impressions per method were made using either an intraoral scanner with scanning abutments for the digital approach or an open-tray technique and polyvinylsiloxane material for the conventional approach. 3D analysis and comparison of implant location on resultant definitive casts were performed using laser scanner and quality control software. The inter-implant distances and interimplant angulations for each implant pair were measured for the reference model and for each definitive cast (n = 20 per group); these measurements were compared to calculate the magnitude of error in 3D for each definitive cast. The influence of implant angulation on definitive cast accuracy was evaluated for both digital and conventional approaches. Statistical analysis was performed using t test (α = .05) for implant position and angulation. Clinical qualitative assessment of accuracy was done via the assessment of the passivity of a master verification stent for each implant pair, and significance was analyzed using chi-square test (α = .05).
A 3D error of implant positioning was observed for the two impression techniques vs the reference model, with mean ± standard deviation (SD) error of 116 ± 94 μm and 56 ± 29 μm for the digital and conventional approaches, respectively (P = .01). In contrast, the inter-implant angulation errors were not significantly different between the two techniques (P = .83). Implant angulation did not have a significant influence on definitive cast accuracy within either technique (P = .64). The verification stent demonstrated acceptable passive fit for 11 out of 20 casts and 18 out of 20 casts for the digital and conventional methods, respectively (P = .01).
Definitive casts fabricated using the digital impression approach were less accurate than those fabricated from the conventional impression approach for this simulated clinical scenario. A significant number of definitive casts generated by the digital technique did not meet clinically acceptable accuracy for the fabrication of a multiple implant-supported restoration.
评估采用数字印模方法制作的种植体最终模型的三维（3D）精度和临床可接受性，并将结果与部分牙列缺失情况下传统印模方法的结果进行比较。
制作一个下颌参考模型，在第一前磨牙和磨牙位置植入种植体，以模拟双侧后牙缺失的患者。每种方法使用带有扫描基台的口内扫描仪进行数字印模法制作10个种植体水平的印模，或使用开放托盘技术和聚乙烯基硅氧烷材料进行传统印模法制作10个种植体水平的印模。使用激光扫描仪和质量控制软件对最终模型上种植体的位置进行三维分析和比较。测量参考模型和每个最终模型（每组n = 20）中每对种植体之间的距离和种植体间角度；将这些测量结果进行比较，以计算每个最终模型在三维空间中的误差大小。评估数字印模法和传统印模法中种植体角度对最终模型精度的影响。使用t检验（α = .05）对种植体位置和角度进行统计分析。通过评估每个种植体对的主验证支架的被动性对精度进行临床定性评估，并使用卡方检验（α = .05）分析显著性。
与参考模型相比，两种印模技术均观察到种植体定位的三维误差，数字印模法和传统印模法的平均±标准差（SD）误差分别为116 ± 94μm和56 ± 29μm（P = .01）。相比之下，两种技术之间的种植体间角度误差没有显著差异（P = .83）。在任何一种技术中，种植体角度对最终模型精度均无显著影响（P = .64）。验证支架显示，数字印模法和传统印模法分别有20个模型中的11个和20个模型中的18个具有可接受的被动适合性（P = .01）。
对于这种模拟临床场景，采用数字印模方法制作的最终模型不如传统印模方法制作的准确。数字技术生成的大量最终模型在制作多个种植体支持的修复体时未达到临床可接受的精度。
