[Comparison of the accuracy of two types of scanning bodies for intraoral scanning in complete-arch implant-supported fixed restoration].

Objective: To compare the accuracy of intraoral scanning for complete-arch implant-supported fixed prosthesis using umbrella scan bodies (USB) and conventional scan bodies (CSB), providing a reference for the clinical application of umbrella-shaped scanning bodies. Methods: A new type of umbrella-shaped scanning body and its matching auxiliary bar were independently developed. A maxillary type Ⅳ dental stone model with six parallel implant abutment analogs was fabricated. Conventional scanning bodies were installed on the model, and a laboratory scanner was used to scan the model as reference data. The CSB, USB, and USB combined with an auxiliary bar (U+SB) were installed on the model, respectively. A single attending physician performed intraoral scanning 10 times for each group using an intraoral scanner, serving as test group data (CSB, USB, U+SB). The test data were best-fit aligned with the virtual abutment models generated from the reference data. The trueness and precision of root-mean-square error (RMSE) values, inter-abutment distance deviations, angular deviations, and scanning time were measured and calculated. Repeated measures ANOVA and generalized estimating equation models were used for statistical analysis. Results: The trueness of RMSE values [(48.0±12.6) and (45.9±13.4) μm] and distance deviations [(64.5±60.2) and (63.8±54.4) μm] of the USB and U+SB groups were significantly better than those of the CSB group [(81.9±23.9) and (90.0±85.2) μm] (all P<0.05). There was no significant difference in trueness of RMSE values and distance deviations between the USB group and U+SB group (all P>0.05). There were no significant differences in the precision of RMSE values and angular deviations among the three groups (all P>0.05). The scanning time of the USB group and U+SB group [(54.3±11.8) and (35.8±10.1) s] was significantly shorter than that of CSB group [(108.7±38.9) s] (all P<0.05). Conclusions: Compared with conventional scanning bodies, the new umbrella-shaped scanning body demonstrates higher accuracy and efficiency for intraoral scanning impressions in complete-arch implant-supported fixed prosthesis.