Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
Department of Fixed Prosthodontics, Faculty of Dentistry, British University in Egypt, Cairo, Egypt.
J Prosthodont. 2024 Mar;33(3):252-258. doi: 10.1111/jopr.13686. Epub 2023 Apr 13.
The aim was to assess the effect of span lengths and total occlusal convergence (TOC) on the accuracy of intraoral scanners .
Two typodont acrylic teeth models were prepared to receive fixed dental prostheses with three different span lengths. Span 1: between maxillary canines; span 2: between maxillary second premolars; and span 3: between maxillary second molars. In the first model, prepared teeth had a TOC of 12°, whereas, in the second model, teeth had a TOC of 20°. Each model was scanned 10 times using 4 different intraoral scanners (Omnicam, Primescan, Trios 4, and Medit i500). The STL files from the scans were compared to the reference models (trueness) and within each test group (precision) using a 3D comparison software. Data were then statistically analyzed.
Regarding trueness, no significant differences were found among Primescan (32.58 ± 13.08), Trios 4 (32.33 ± 12.19), and Medit i500 (32.26 ± 9.57). However, all showed significantly better trueness than Omnicam (35.70 ± 8.35) (p < 0.001). The highest values were found in scans between the second molars (47.42 ± 3.94), followed by scans between second premolars (28.42 ± 3.78), and the highest trueness was found in scans between the canines (23.80 ± 3.85). For TOC, 12° had a significantly higher value than 20° (p < 0.001). Regarding precision, the highest values were found with Omnicam (29.84 ± 3.89), followed by Medit i500 (28.04 ± 2.94), then Trios 4 (25.64 ± 3.11), and Primescan (24.69 ± 5.25). The highest values and least precision were found in scans between the second molars (28.97 ± 5.27) and scans between second premolars (27.59 ± 3.97), whereas the highest precision was found in scans between the canines (24.60 ± 2.04). For TOC, 12° had significantly higher values than 20° (p < 0.001).
Intraoral scans are directly affected by scanner type, TOC, and scan spans. All tested scanners showed clinically acceptable results even for long-span restorations.
评估跨度长度和总覆（牙合）（TOC）对口腔内扫描仪准确性的影响。
制备了两个技工室丙烯酸牙模型，以接收具有三种不同跨度长度的固定义齿。跨度 1：上颌尖牙之间；跨度 2：上颌第二前磨牙之间；跨度 3：上颌第二磨牙之间。在第一个模型中，预备牙的 TOC 为 12°，而在第二个模型中，牙的 TOC 为 20°。使用 4 种不同的口腔内扫描仪（Omnicam、Primescan、Trios 4 和 Medit i500）对每个模型进行了 10 次扫描。使用 3D 比较软件将扫描的 STL 文件与参考模型（准确性）和每个测试组内（精密度）进行比较。然后对数据进行了统计学分析。
关于准确性，Primescan（32.58±13.08）、Trios 4（32.33±12.19）和 Medit i500（32.26±9.57）之间没有显著差异。然而，所有这些都明显优于 Omnicam（35.70±8.35）（p<0.001）。在扫描第二磨牙之间时发现了最高值（47.42±3.94），其次是扫描第二前磨牙之间（28.42±3.78），扫描尖牙之间时的准确性最高（23.80±3.85）。对于 TOC，12°明显高于 20°（p<0.001）。关于精密度，Omnicam 具有最高值（29.84±3.89），其次是 Medit i500（28.04±2.94），然后是 Trios 4（25.64±3.11）和 Primescan（24.69±5.25）。在扫描第二磨牙之间（28.97±5.27）和扫描第二前磨牙之间（27.59±3.97）时发现了最高值和最低的精密度，而在扫描尖牙之间时的精密度最高（24.60±2.04）。对于 TOC，12°明显高于 20°（p<0.001）。
口腔内扫描仪直接受到扫描仪类型、TOC 和扫描跨度的影响。所有测试的扫描仪即使对于长跨度修复体也显示出临床可接受的结果。
