Sun Minji, Oh Kyung Chul, Kim Jaeyoung, Moon Hong Seok
Clinical Assistant Professor, Department of Prosthodontics, Ewha Womans University Mokdong Hospital, Seoul, Republic of Korea.
Associate Professor, Department of Prosthodontics, Yonsei University College of Dentistry, Seoul, Republic of Korea.
J Prosthet Dent. 2025 Sep;134(3):764.e1-764.e9. doi: 10.1016/j.prosdent.2025.06.001. Epub 2025 Jul 1.
The rapid advancement of intraoral scanners and the widespread adoption of dental implant scan bodies have streamlined the digital acquisition of implant position data and the subsequent fabrication of implant-supported prostheses. However, research on the fit of multiunit implant-supported fixed dental prostheses (FDPs) fabricated using a cast-free workflow is sparse.
The purpose of this study was to evaluate the internal and marginal fit of 6-unit implant-supported FDPs fabricated from zirconia by using different intraoral scanning protocols and digital data superimposition and analysis techniques.
A definitive cast with implants placed in the maxillary right canine, right central incisor, and left canine positions was fabricated to simulate the partial edentulism of the 6 maxillary anterior teeth. Implant scan bodies were attached to the implants, and 10 consecutive intraoral scans were made. Custom abutments were designed based on one of the scan datasets, and 6-unit zirconia prostheses (n=10) were fabricated in a single-step cast-free workflow (Group IL). The designed custom abutments were then fabricated and tightened onto the definitive cast, followed by an additional set of 10 intraoral scans to fabricate another set of 6-unit zirconia prostheses (Group AL; n=10). The intraoral scan data were analyzed by using a cube-embedded implant scan body library and custom abutment dataset. Distances between each cube in the intraoral scan data were measured, and their ratios calculated relative to those obtained from tabletop scan data. Additionally, implant angulation was measured, and angular discrepancies between implant pairs were calculated. The fabricated prostheses were fitted onto the definitive cast, and internal and marginal gaps were assessed by using 3-dimensional data superimposition techniques. The data were analyzed by using a 2-way analysis of variance test (α=.05).
The distance ratio in Group IL was significantly closer to the reference value than that in Group AL (P<.001). The angular discrepancy between implant positions was significantly smaller in Group IL than in Group AL (P<.001). The mean internal gap in Group AL was significantly greater than that in Group IL (P=.007). However, no significant difference was observed between the groups when comparing the marginal gaps of the zirconia prostheses (P>.05).
Zirconia prostheses fabricated through a single-step, cast-free workflow exhibited significantly smaller internal gaps than those fabricated through a 2-step process. However, the marginal fit of the zirconia prostheses did not significantly differ between the 2 scanning protocols.
口腔内扫描仪的迅速发展以及牙科种植扫描体的广泛应用，简化了种植体位置数据的数字化采集以及随后种植体支持的修复体的制作。然而，关于采用无模型工作流程制作的多单位种植体支持的固定义齿（FDP）适合性的研究却很少。
本研究的目的是评估使用不同的口腔内扫描方案以及数字数据叠加和分析技术，由氧化锆制作的6单位种植体支持的FDP的内部适合性和边缘适合性。
制作一个带有种植体的最终模型，种植体分别位于上颌右侧尖牙、右侧中切牙和左侧尖牙位置，以模拟上颌6颗前牙的部分牙列缺损。将种植扫描体连接到种植体上，进行10次连续的口腔内扫描。基于其中一个扫描数据集设计定制基台，并采用一步法无模型工作流程制作6单位氧化锆修复体（IL组，n = 10）。然后制作设计好的定制基台并拧紧到最终模型上，接着再进行一组10次口腔内扫描，以制作另一组6单位氧化锆修复体（AL组，n = 10）。使用包含植入体扫描体库和定制基台数据集的软件对口腔内扫描数据进行分析。测量口腔内扫描数据中每个立方体之间的距离，并计算其相对于桌面扫描数据获得的距离的比率。此外，测量种植体角度，并计算种植体对之间的角度差异。将制作好的修复体安装到最终模型上，使用三维数据叠加技术评估内部和边缘间隙。采用双向方差分析检验对数据进行分析（α = 0.05）。
IL组的距离比率比AL组更接近参考值（P <.001）。IL组种植体位置之间的角度差异明显小于AL组（P <.001）。AL组的平均内部间隙明显大于IL组（P = 0.007）。然而，比较氧化锆修复体的边缘间隙时，两组之间未观察到显著差异（P >.05）。
通过一步法无模型工作流程制作的氧化锆修复体的内部间隙明显小于通过两步法制作的修复体。然而，两种扫描方案下氧化锆修复体的边缘适合性没有显著差异。
