A novel post-processing strategy to improve the accuracy of complete-arch intraoral scanning for implants: an in vitro study

Objectives: To develop a new post-processing strategy that utilizes an auxiliary device to adjust intraoral scans and improve the accuracy of 3D models of complete-arch dental implants. Materials and methods: An edentulous resin model with 6 dental implants was prepared. An auxiliary device, consisting of an opaque base and artificial landmarks, was fabricated and mounted onto the resin model. Twenty intraoral scans (raw scans) were taken using this setup. A new post-processing strategy was proposed to adjust the raw scans using reverse engineering software (verified group). Additionally, ten conventional gypsum casts were duplicated and digitized using a laboratory scanner. The linear and angular trueness and precision of the models were evaluated and compared. The effect of the proposed strategy on the accuracy of complete-arch intraoral scans was analyzed using one-way ANOVA. Results: The linear trueness (29.7 mu m) and precision (24.8 mu m) of the verified group were significantly better than the raw scans (46.6 mu m, 44.7 mu m) and conventional casts (51.3 mu m, 36.5 mu m), particularly in cross-arch sites. However, the angular trueness (0.114 degrees) and precision (0.085 degrees) of the conventional casts were significantly better than both the verified models (0.298 degrees, 0.168 degrees) and the raw scans (0.288 degrees, 0.202 degrees). Conclusions: The novel post-processing strategy is effective in enhancing the linear accuracy of complete-arch implant IO scans, especially in cross-arch sites. However, further improvement is needed to eliminate the angular deviations. Clinical significance: Errors generated from intraoral scanning in complete edentulous arches exceed the clinical threshold. The elimination of stitching errors in the raw scans particularly in the cross-arch sites, through the proposed post-processing strategy would enhance the accuracy of complete-arch implant prostheses.