Effect of Remaining Teeth on Complete Arch Implant Scanning: An In Vitro Comparison of Interabutment Deviations in Two Digital Workflows

This in vitro study evaluated whether the presence of four remaining teeth affected the reproduction of interabutment spatial relationships by two intraoral scanning systems. A single three-dimensionally printed maxillary master model containing four implant analogues connected to Mini Conical Abutments was evaluated sequentially under partially dentate (M1) and fully edentulous (M2) conditions. M2 was obtained by removing the four remaining teeth from M1 while maintaining the implant configuration. Reference datasets were acquired using an MDX 40 mechanical contact scanner. Ten optical scans were obtained for each combination of scanner and model condition using TRIOS II and iTero Element, resulting in 40 experimental datasets. Six interabutment distances were calculated from the three-dimensional coordinates of the four abutment centres. For each scan, the root mean square error (RMSE) of the six distance discrepancies relative to the corresponding reference dataset was calculated. Data were analyzed using two-way analysis of variance and Tukey’s test (α = 0.05). Mean RMSE values were 0.141 ± 0.044 mm for TRIOS M1, 0.215 ± 0.080 mm for TRIOS M2, 0.143 ± 0.053 mm for iTero M1, and 0.116 ± 0.037 mm for iTero M2. Significant effects were detected for the scanner system (p = 0.009) and the interaction between the scanner system and model condition (p = 0.007), whereas the model condition alone was not significant (p = 0.194). TRIOS M2 showed significantly greater RMSE than the other groups, while the two iTero conditions did not differ significantly. Under the evaluated conditions, removal of the four remaining teeth affected the reproduction of interabutment relationships differently in the two digital workflows.