# Trial data for precision analysis of a three-dimensional mandibular mechanical advantage

## TL;DR

This study provides trial data for analyzing the mechanical advantage of masticatory muscles in a 3D model of the mandible.

## Contribution

The paper introduces trial data and a method for calculating 3D mechanical advantage in mandibular function.

## Key findings

- Cone-beam CT scans from 30 subjects were used to determine craniofacial landmarks and muscle moment arms.
- Interexaminer differences were observed, especially in biomechanical variable measurements.
- The data were used to assess reliability and error in a published reliability study.

## Abstract

The data presented in this manuscript describe craniofacial landmark coordinate values, muscle and load moment arm lengths, and mechanical advantage rates for constructing a three-dimensional model of masticatory muscles. Cone-beam computed tomography scans from 30 subjects (aged 12–19 years, 16 females) were used. Thirty-six craniofacial landmarks were identified. Subsequently, the moment arms for 7 muscles and their corresponding load moment arms at incisor and molar positions were determined. Then, the three-dimensional mechanical advantage for each muscle and tooth position was calculated as the ratio of muscle moment arm to load moment arm. This procedure was repeated three times by a main examiner and once by two other examiners. The Friedman test and the square root of the 'method of moments' variance estimator were used to compare data among examiners and calculate random errors, respectively. Although the values for the craniofacial landmark coordinates and biomechanical variables are very close, differences were found between measurements, especially in the interexaminer comparisons. Values served as the basis for reliability (intraclass correlation coefficient) and errors (average mean of absolute differences) analysis in the research paper titled “A three-dimensional method to calculate mechanical advantage in mandibular function: Intra- and interexaminer reliability study,” published in the Journal of Orofacial Orthopedics.