RESUMO
PURPOSE: To compare the accuracy of a partially digital cross-mounting workflow of direct scans of interocclusal records to a conventional workflow by analyzing the deviations of sequentially cross-mounted casts. MATERIALS AND METHODS: A set of reference casts, comprising maxillary and mandibular full-arch prepared casts and interim prostheses, was articulated, mounted, and scanned to generate four reference casts for cross-mounting. In the conventional approach, 15 sets of these four casts were printed. Polyvinylsiloxane (PVS) records were made using the reference casts and utilized for sequential cross-mounting. In the partially digital group, the same PVS interocclusal records were scanned and used for digital cross-mounting via design software. The mean deviations of both groups from the reference cast were analyzed using a 3D inspection software program. Statistical tests, including paired t-test and analysis of variance (ANOVA), were conducted to compare the average discrepancies between the two groups and to evaluate discrepancies in the anterior and posterior regions (α = 0.05). RESULTS: The range of discrepancies was similar in both the conventional and partially digital groups. The final set of related casts had a mean deviation of 201.58 ± 136.98 mm in the conventional workflow and 248.69 ± 164.71 mm in the partially digital workflow. No statistically significant difference was found between conventional and partially digital groups (p = 0.091). Error propagation was examined by comparing discrepancies at each step within the cross-mounting process. In the conventional group, no significant difference was found (p = 0.148), but a significant difference was found among groups in the partially digital group at each step of sequential mounting (p < 0.001). A significant difference was observed between anterior and posterior deviations in the partially digital group (p < 0.001), but not in the conventional group (p = 0.143). CONCLUSIONS: The study reveals that there is no statistically significant difference between conventional and partially digital cross-mounting workflows. However, within the partially digital group, a significant difference in deviation emerges across cross-mounting steps, with increased deviation in the anterior region.
RESUMO
STATEMENT OF PROBLEM: Alternatives to the bilateral interocclusal registration scanning technique to improve virtual articulation have not been fully investigated. PURPOSE: The purpose of this in vitro study was to compare the accuracy of virtually articulating digital casts by using bilateral interocclusal registration scans versus a complete arch interocclusal scan. MATERIAL AND METHODS: A set of maxillary and mandibular reference casts were hand-articulated and mounted on an articulator. The mounted reference casts were scanned, and the maxillomandibular relationship record was scanned 15 times using 2 different scanning techniques, the bilateral interocclusal registration scan (BIRS) and complete arch interocclusal registration scan (CIRS), with an intraoral scanner. The generated files were transferred to a virtual articulator, and each set of scanned casts was articulated using BIRS and CIRS. The virtually articulated casts were saved as a set and transferred to a 3-dimensional (3D) analysis program. The scanned casts were set in the same coordinate system as the reference cast and overlaid on top of the reference cast for analysis. Two anterior and 2 posterior points were selected to determine points of comparison between the reference cast and test casts virtually articulated with BIRS and CIRS. The mean discrepancy between the 2 test groups and the anterior and posterior mean discrepancy within each group were tested for significance by using the Mann-Whitney U test (α=.05). RESULTS: A significant difference was found between the virtual articulation accuracy of BIRS and CIRS (P<.001). The mean deviation for BIRS was 0.053 ±0.051 mm and that for CIRS was 0.265 ±0.241 mm. Furthermore, significant differences were found between the anterior and posterior deviations in both BIRS (P=.020) and CIRS (P<.001). The mean deviation for BIRS was 0.034 ±0.026 mm in the anterior and 0.073 ±0.062 mm in the posterior. The mean deviation for CIRS was 0.146 ±0.108 mm anteriorly and 0.385 ±0.277 mm posteriorly. CONCLUSIONS: BIRS was more accurate than CIRS for virtual articulation. Moreover, the alignment accuracy of anterior and posterior sites for both BIRS and CIRS exhibited significant differences, with the anterior alignment exhibiting better accuracy in relation to the reference cast.
RESUMO
STATEMENT OF PROBLEM: The use of digital interocclusal registration scans for virtual articulation and mounting has been studied extensively; however, the accuracy of the cross-mounting procedures in a digital workflow is not well understood. PURPOSE: The purpose of this in vitro study was to compare the accuracy of digital and conventional cross-mounting by measuring the 3-dimensional deviation at each step of sequential cross-mounting. MATERIAL AND METHODS: A set of reference casts and complete-arch interim restorations was prepared for complete-arch complete-coverage restorations, hand-articulated, and mounted in an articulator. The reference casts were then scanned with and without the interim restorations to generate 4 reference casts for cross-mounting. For the conventional group, 15 sets of the 4 casts were printed. Polyvinyl siloxane interocclusal registration records were made of the reference casts for each set, and casts were sequentially cross-mounted. For the digital workflow, 15 sets of bilateral interocclusal registration scans were made of the mounted reference casts and used to align the cast scans. Three-dimensional deviations at 2 anterior and 2 posterior points were recorded between the experimental mountings and the reference casts on each set of casts. Nonpaired t test and analysis of variance (ANOVA) were used to compare the average discrepancy between the 2 groups, and the pooled anterior versus posterior discrepancies were compared (α=.05). RESULTS: A significant difference was found between conventional and digital cross-mounting procedures (P<.001), but no significant difference was found in either group, conventional (P=.116) or digital (P=.987), at each step of the sequential mountings. The mean ±standard deviation at the final set of related casts in the conventional workflow was 201.6 ±137.0 µm and that in the digital group was 50.3 ±47.5 µm, with a significant difference between anterior and posterior deviations in the digital group (P=.028), but not in the conventional group (P=.143). The mean ±standard deviation anterior conventional deviation was 175.6 ±119.2 µm and that in the digital group was 36.9 ±30.9 µm. The mean ±standard deviation posterior conventional deviation was 227.6 ±50.2 µm and that in the digital group was 63.7 ±57.2 µm. CONCLUSIONS: Digital cross-mounting was more accurate than conventional cross-mounting, although increased deviation was found in the anterior region compared with the posterior region.
