Avaliação de efeitos no primeiro pré-molar superior após expansão rápida da maxila em tomografias de cone beam

Abstract

Maxillary deficiency and posterior crossbite are frequent malocclusions in growing patients. The rapid maxillary expansion procedure (RME) is indicated for the treatment of transverse deficiency during mixed or young permanent dentition. ERM promotes forces that can generate changes to adjacent and/or supporting tissues of the anchoring teeth. The objectives of this study were: 1) to review the literature on the effects of RME on the upper arch perimeter; and 2) to verify, by means of a retrospective clinical study, the support structures of the teeth that received the Hyrax type fixed expansion device. In the systematic review of the literature, clinical studies were selected on alterations resulting in the teeth and their support structures from the RME procedure. The inclusion criteria were papers published in English, in journals indexed in the SCOPUS, and Pubmed databases with details on the RME methods used. In the experimental study, Cone Beam computed tomographies (CBCT) of individuals treated at the Post-Graduation Clinic in Orthodontics (PUCRS) were selected, who underwent the RME procedure, with two protocols for the expansion screw (expansion x expansions and alternating constrictions of the maxilla), to evaluate periodontal insertion, alveolar thickness, and inter-premolar and molar distance, at the initial and 6 months after the active phase of the expansion. For the literature review, 24 articles were selected, 10 of which were analyzed, as they evaluated and quantified the RME changes in the support structures and adjacent tissues. In the clinical study, a significant reduction in the thickness of the buccal alveolar bone was observed after RME. The alternate maxillary expansion and constriction protocol (ERMC) significantly decreased the height of the alveolar bone crest and increased the thickness of the alveolar buccal bone. Root and cusp distance increased in both groups. With the expansion-only protocol (ERM) there was greater preservation of the bone height of the alveolar ridges. According to the literature review, the anchoring teeth of the expansion appliance tend to have a loss of alveolar structure and root changes. There is an increase in the arch perimeter and in the inter-molar distance. CBCT is considered the best method for evaluating dental structures and support tissues. The clinical study revealed that both expansion protocols promoted alveolar bone resorption and reduced the bone height of the alveolar crest. There was also an increase in the inter-premolar distances at the level of the cusp and root tips.