Assessment of the bone thickness of the palate on cone-beam computed tomography for placement of miniscrew-assisted rapid palatal expansion appliances.

INTRODUCTION: The correction of maxillary transverse discrepancy is achieved by means of rapid maxillary expansion, which may be performed by conventional or surgically-assisted rapid maxillary expansion, and more recently, by miniscrew-assisted rapid palatal expansion (MARPE). This study assessed the bone thickness of the palate on cone-beam computed tomography (CBCT) images for placement of mini-implants and anchorage of MARPE. METHODS: The sample consisted of 223 CBCT scans from patients of both genders (137 females and 86 males) aged ≥18 years. By using the Image Studio software (Anne Solutions, São Paulo, Brazil), measurements of the bone thickness of the palate were performed bilaterally, as follows: in the axial plane, the bone thicknesses were determined in the anterior region (distal face of the first premolars) and the posterior region (distal face of the first molars), at 3 mm and 6 mm laterally to the midpalatal suture. So in the sagittal plane, the bone thicknesses of the palate were measured in these placements from the palatal cortical to the nasal floor cortical in the anterior region at 30°, 45°, and 90°. In the posterior region, the bone thickness was determined only at 90°. The statistical tests used were the Kruskal-Wallis H test (analysis of variance on ranks) with Dunn's post-hoc test and Mann-Whitney U test (P <0.05). RESULTS: The bone thickness of the palate in the anterior region varied from 8.57 mm in women to 11.28 mm in men at 3 mm from the midpalatal suture and from 7.99 mm in women to 10.47 mm in men at 6 mm for 30°; from 6.35 mm in women to 9.28 mm in men at 3 mm from the midpalatal suture and from 6.20 mm in women to 8.88 mm in men at 6 mm for 45°; from 4.51 mm in women to 6.85 mm in men at 3 mm from the midpalatal suture and from 4.29 mm in women to 6.64 mm in men at 6 mm for 90°. In the posterior region, the bone thickness varied from 2.93 mm (3 mm from the suture) to 1.78 mm (6 mm from the suture) for women and from 3.24 mm (3 mm from the suture) to 1.99 mm (6 mm from the suture) for men. In general, the bone thickness of the palate is greater in the anterior region at 3 mm from the midpalatal suture at 30°. CONCLUSIONS: There was high variability in the bone thickness of the palate among patients and in different areas. Therefore, it is necessary to make an individualized diagnosis of the patient and manufacture the MARPE appliance carefully by performing a prior evaluation of the palatal bone thickness by means of CBCT to determine the ideal sites and inclinations for placement of mini-implants.

Reference standard thickness for bone plates of upper teeth: an ultra-high-resolution study using tomographic mapping / Padrão de referência de espessura para cristas ósseas de dentes superiores: um estudo de ultra-alta resolução usando mapeamento tomográfico

Objective: it is important to know the thicknesses of the alveolar bone plates (ABPs) based on the current literature for the planning and success of orthodontic treatment. However, studies have scientific limitations regarding ABPs as the image resolution is not adequate and is restricted to a few teeth or buccal face only. This study was aimed at reporting a reference standard for bone plates of upper teeth, in which 15 patients (mean age of 21.79 years) with balanced occlusion and a harmonious facial profile were evaluated using cone-beam computed tomography at a voxel size of 0.1 mm. Material and Methods: bone tissues of the cervical, middle, and apical thirds of the root (buccal and palatal), the distance between cement-enamel junction (CEJ) and alveolar bone crest (ABC), and inclination of the teeth to the palatal plane were evaluated. Paired t-test, Spearman's correlation tests, and linear regression tests were used (P < 0.05). Results: the buccal distance between the CEJ and ABC was greater than the palatal one in all pairs of teeth. Most of the bone tissues had a thickness ≤ 1 mm in the buccal face, whereas in the cervical-apical direction, the thickness was ≥ 2 mm. There is no equivalence between genders in the sample. Conclusion: the reduced buccal bone architecture around the first premolars was indicative of local gingival recessions, and the lack of gender uniformity was suggestive of individual evaluation. References of normal bone tissue determining the orthodontic limits were provided to assist in the treatment planning. (AU)

Objetivo: é importante conhecer as espessuras das cristas ósseas alveolares (COAs) com base na literatura atual para o planejamento e sucesso do tratamento ortodôntico. No entanto, os estudos apresentam limitações científicas em relação às COAs, pois a resolução da imagem não é adequada e está restrita apenas a alguns dentes ou face vestibular. Este estudo teve como objetivo descrever um padrão de referência para corticais ósseas de dentes superiores, no qual 15 pacientes (idade média de 21,79 anos) com oclusão equilibrada e perfil facial harmonioso foram avaliados por meio de tomografia computadorizada de feixe cônico no tamanho de voxel de 0,1 mm. Material e Métodos: os tecidos ósseos dos terços cervical, médio e apical da raiz (vestibular e palatina), a distância entre a junção cemento-esmalte (JCE) e a crista óssea alveolar (COA) e a inclinação dos dentes ao plano palatino foram avaliados. Foram utilizados o teste t pareado, os testes de correlação de Spearman e os testes de regressão linear (P < 0,05). Resultados: a distância vestibular entre a JEC e a COA foi maior que a palatina em todos os pares de dentes. A maioria dos tecidos ósseos apresentou espessura ≤ 1 mm na face vestibular, enquanto no sentido cérvico-apical a espessura foi ≥ 2 mm. Não há equivalência entre os gêneros na amostra. Conclusão: a arquitetura óssea vestibular reduzida ao redor dos primeiros pré-molares foi indicativa de recessões gengivais locais, e a falta de uniformidade de gênero foi sugestiva de avaliação individual. Referências de tecido ósseo normal determinando os limites ortodônticos foram fornecidas para auxiliar no planejamento do tratamento. (AU)