# Relationship between palatal bone thickness and maxillary transverse deficiency in skeletal class II adults: A cone-beam computed tomography analysis

## TL;DR

This study uses CT scans to find that narrower upper jaws in certain patients correlate with thicker bone in the back of the palate.

## Contribution

The study identifies a significant correlation between posterior palatal bone thickness and maxillary transverse deficiency in skeletal Class II adults.

## Key findings

- A narrower maxilla correlates with greater posterior palatal thickness in skeletal Class II individuals.
- Posterior maxillary thickness (PMT) significantly influences the maxillary atresia index.
- A low but significant correlation was found between maxillary atresia and nasopalatine canal thickness (NCT) and PMT.

## Abstract

Maxillary Transverse Deficiency (MTD) is a condition that affects the balance and functionality of the stomatognathic system. The aim was to evaluate maxillary bone thickness at the level of the midpalatal suture (MPS) using Cone Beam Computed Tomography (CBCT) in skeletal Class II individuals with maxillary transverse deficiency (MTD) and those with normal transverse maxillary width.

A total of 111 complete cranial scans from patients aged 18 years or older with skeletal Class II malocclusion were analyzed. This classification was confirmed by measuring the ANB angle and convexity at point A. The patients were divided into two groups based on their transversal conditions: the normal transversal maxillary width group (n=46) and the atresia group (n=65). The classification followed the University of Pennsylvania (U-Penn) method using Planmeca Romexis® software. Additionally, the vertical thickness of the maxillary bone was measured at three specific points (anterior, middle, and posterior) using sagittal views. Four maxillary thickness measurements were evaluated: nasopalatine canal thickness (NCT), middle maxillary thickness (MMT), anterior maxillary thickness (AMT), and posterior maxillary thickness (PMT). Statistical analyses included Student's t-test, linear multiple regression, and Pearson correlations.

The maxillary atresia index showed a mean difference of 5.82 mm between the two groups (p<0.001), favoring the adequate-width group. The four maxillary thickness measurements evaluated did not show significant differences between the groups (p>0.05). Furthermore, a low but significant correlation was found between maxillary atresia and bone thickness in the nasopalatine canal and the posterior maxilla, specifically for NCT (R=0.202, p=0.033) and PMT (R=0.205, p=0.031). Among all the analyzed variables using multiple linear regression, only the posterior maxillary thickness (PMT) was found to influence the occurrence of atresia significantly. It was determined that for every millimeter increase in this thickness, the maxillary atresia index increased by 0.78 points (p=0.005).

The transverse dimensions of the maxilla in individuals with skeletal Class II affect its vertical dimensions; regardless of the initial transverse condition, a narrower maxilla correlates with greater posterior palatal thickness.