Comparison of accuracy in digital and conventional cross-mounting

Dianne Luu; Elena Kan; Soo-Woo Kim; Jason D Lee; Sang J Lee

doi:10.1016/j.prosdent.2022.11.001

Comparison of accuracy in digital and conventional cross-mounting

J Prosthet Dent. 2022 Dec 3:S0022-3913(22)00693-X. doi: 10.1016/j.prosdent.2022.11.001. Online ahead of print.

Authors

Dianne Luu¹, Elena Kan¹, Soo-Woo Kim², Jason D Lee³, Sang J Lee⁴

Affiliations

¹ Graduate student, Graduate Prosthodontics, Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, Mass.
² Lecturer, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Mass.
³ Instructor, Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, Mass.
⁴ Assistant Professor, Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, Boston, Mass. Electronic address: sang_lee@hsdm.harvard.edu.

PMID: 36473749
DOI: 10.1016/j.prosdent.2022.11.001

Abstract

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.