Creating and analyzing digital scans of a mandibulectomy cast with simulated trismus

Yuan Gao; Mariko Hattori; Yuka I Sumita; Noriyuki Wakabayashi

doi:10.1016/j.prosdent.2023.09.036

Creating and analyzing digital scans of a mandibulectomy cast with simulated trismus

J Prosthet Dent. 2023 Oct 31:S0022-3913(23)00652-2. doi: 10.1016/j.prosdent.2023.09.036. Online ahead of print.

Authors

Yuan Gao¹, Mariko Hattori², Yuka I Sumita³, Noriyuki Wakabayashi⁴

Affiliations

¹ Doctor and Researcher, Department of Comprehensive Treatment Clinic 2, Dalian Stomatological Hospital, Dalian, PR China.
² Assistant Professor, Department of Advanced Prosthodontics, Tokyo Medical and Dental University (TMDU), Tokyo, Japan. Electronic address: sasamfp@tmd.ac.jp.
³ Professor, Division of General Dentistry 4, The Nippon Dental University Hospital, Tokyo, Japan.
⁴ Professor and Chair, Department of Advanced Prosthodontics, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.

PMID: 37919132
DOI: 10.1016/j.prosdent.2023.09.036

Abstract

Statement of problem: Trismus associated with maxillofacial defects resulting from tumor resection or radiotherapy can make dental treatment uncomfortable for patients. Using an intraoral scanner instead of making a conventional impression could help to make prosthetic rehabilitation more comfortable. However, limited information is available regarding the feasibility and accuracy of intraoral scanners for scanning mandibular defects.

Purpose: The purpose of this in vitro study was to evaluate the feasibility and accuracy of using an intraoral scanner to digitize a cast of a mandibular defect under various simulated trismus conditions.

Material and methods: An intraoral scanner was used to scan the mandibular cast under different simulated degrees of trismus (mouth opening 10, 20, and 30 mm) and nontrismus (mouth opening 40 mm). The surface areas captured were compared. The datasets were loaded into a 3-dimensional (3D) evaluation software program and then superimposed for precision analysis and on reference data for trueness analysis. One-way analysis of variance was used to compare surface area captured, precision, and trueness of the measurement under the different mouth opening conditions (α=.05).

Results: The surface area for which 3D data were obtained by the intraoral scanner ranged from 3199.1 to 6161.6 mm². The area differed significantly under all mouth opening conditions (P=.001), with a smaller scanned surface area captured in severe trismus (10 mm). Precision ranged from 0.032 to 0.056 mm, and trueness from 0.037 to 0.076 mm. No significant differences were seen in precision (P=.312), but significant differences were seen in trueness (P=.016) under all trismus conditions.

Conclusions: Using an intraoral scanner appears feasible for digitizing mandibular defect casts with simulated mild and moderate trismus. The accuracy of the obtained data was clinically acceptable.