# Assessment of the relationship between facial, skeletal, dental and smile asymmetries: a preliminary investigative analysis

## TL;DR

This study explores how facial, skeletal, dental, and smile asymmetries are related in patients with normal vertical facial patterns.

## Contribution

The study identifies a significant correlation between subdivision malocclusion and upper midline dental deviation.

## Key findings

- Subdivision malocclusions significantly correlate with upper midline dental deviation (R2 = 0.25).
- Individuals without subdivision malocclusions showed 0.66 mm less upper midline deviation (P = 0.026).
- Facial asymmetry was assessed using calibrated measurements from photographs and CBCT scans.

## Abstract

This study aimed to investigate the relationship between asymmetrical faces, smiles, skeletal parameters and dental asymmetries.

A total of 20 patients with normal vertical facial pattern (20≤FMA≤30°) were selected to analyze frontal extraoral photographs with natural smiles and 3D frontal images generated by cone beam computed tomography scans (CBCT scans). The facial symmetry was retrieved by tracing the bipupillary line and perpendicular lines, the distance between the right and left frontolacrimal sutures was subsequently transferred to the same area in the photographs (the intercanthal distance) to calibrate all measures in the study. An assessment of mandibular chin deviation was conducted, and lines were traced to evaluate the dental midline and smile parameters. Through the manipulation of the CBCT scan, the presence of malocclusion and its respective subdivision, as well as the presence of unilateral or bilateral posterior crossbites in each patient, were identified. Data normality was checked using the Shapiro-Wilk test, and univariate linear regressions were performed to assess relationships.

Individuals with Menton point (Me point) deviation greater than 3.5 mm were considered asymmetrical. Subdivision malocclusions significantly correlated with upper midline dental deviation (UMLDD; R2= 0.25), with individuals without subdivision malocclusions showing 0.66 mm less deviation (95% CI = -1.24, -0.09; P = 0.026).

UMLDD have a significant correlation with subdivision malocclusion.