Tomographic mapping of the hard palate and overlying mucosa

Abstract

The aim of this study was to measure the thickness of the hard palate and its overlying mucosa using cone-beam computed tomography (CBCT), for purposes of miniscrew placement. The sample comprised 36 CBCT scans of patients aged 12 to 52 years from a database of the Orthodontics Department of the Federal University of Rio de Janeiro. Paracoronal views of the palatal region were reconstructed at 4, 8, 16 and 24 mm posterior to the incisive foramen. In each reconstruction measurements were taken at the suture, 3 mm and 6 mm bilaterally to it. Wilcoxon's test verified the differences between the selected regions. Total bone height decreased from the anterior to the posterior region. In cross sections 4, 16 and 24, bone height decreased from the suture laterally to the 3 mm region and then increased in the 6 mm region. The cortical thickness does not seem to be a concern because it presented a mean thickness of at least 1 mm at all sites evaluated. The measurements of the mucosa thickness decreased from lateral to median and from anterior to posterior regions. The most suitable areas for miniscrew placement in the palate are located 4 mm posterior to the incisive foramen, in the median or paramedian regions 3 mm adjacent to the suture.

Cone Beam Computed Tomography evaluation of palatal bone thickness for miniscrew placement in Down's syndrome

“…In contrast, when Gracco et al, 11 used CBCT to analyse the PBT of 162 patients aged between 10 and 44 years and distributed into three groups (10-15 years, 15-20 years and >20 years), they found no significant differences in PBT between the groups. In agreement with those results and with the reports of other studies on the general population, 15,21,24 we observed no significant effect of age on PBT, either in individuals with DS or in controls. Justification of radiological examination must be particularly rigorous in children, as the radiation exposure dose in these patients is greater than in adults when the same exposure parameters are used.…”

“…In the present study, PBT usually decreased progressively in a lateral direction from the midline and also in an anteroposterior direction, with exception of the area of the median palatal suture; these findings confirm the results of previous series in the general population. 15,22,23 In the most anterior paracoronal sections from individuals with DS we detected an exception to this rule, as the PBT in the paramedian sections at 6 mm from the midline was greater than in the sections at 3 mm from the midline; we have not found any results in the literature with which to compare this finding. Nor have we been able to corroborate in other studies the morphometric differences in PBT observed between the DS group and controls in the area of the palatal suture and in the paramedian sections.…”

“…In the present study, the ''area of confidence'' (!4 mm in !75% of the participants evaluated) both in the DS group and in controls was limited to the area around the median palatal suture and, as a second option, to the most anterior paramedian sites, coinciding with the results of other studies. 15,21 However, the median palatal suture is crucial for the development and growth of the maxilla, and experimental models in animals have shown that the insertion of implants at this level can restrict transverse expansion of the maxilla. 27 As a result, some authors have suggested that miniscrews should preferably be inserted in the paramedian areas of the palate in children and adolescents.…”

“…15 Twenty points were selected to make the palatal bone measurements, using the pattern described by Gracco et al 11 First, the anterior palatine foramen (incisive foramen) was located on the axial section and four coronal sections of the palatine region were selected, 4, 8, 16 and 24 mm posterior to the posterior wall of the foramen (Fig. 1A).…”

“…10 The advantages of this site include ease of installation and the low risk of causing damage to adjacent anatomical structures. 11 The majority of studies performed to date to evaluate palatal bone thickness (PBT) and to determine the ideal position for placement of the TAD confirm that the anterior part of the palatine bone is the best area for the insertion of these devices [11][12][13][14][15] ; however, there is considerable interindividual variability and results cannot simply be extrapolated to the whole population.…”