Cephalometric Study through Lateral Cephalograms of Dentoskeletal Changes Following the Use of Three Maxillary Expansion Appliances: Bonded, Haas and Hyrax

Fausto Silva BRAMANTE, Renato Rodrigues de ALMEIDA

The objective of this cephalometric study was to compare, through lateral cephalograms, the dentoskeletal changes following the use of three types of rapid maxillary expansion appliances, Haas, Hyrax and bonded with a full occlusal acrylic coverage. The sample consisted of 64 subjects presenting uni or bilateral posterior crossbite. The lateral cephalograms were taken before treatment (preexpansion), immediately after expansion and three months after retention. Results demonstrated that immediately after rapid maxillary expansion only the group with the bonded maxillary expander showed a statistically significant anterior displacement of the maxilla, while the other appliances groups showed no significant displacement. However, after the retention period, this significant displacement returned to values close to its initial and no statistically significant difference was found in the displacement among the groups. Additionally, after the retention period, an inferior displacement of the maxilla was shown in the three groups, causing a slight clockwise rotation of the mandible, while the lower anterior facial height underwent a statistically significant increase in the three groups, nevertheless, no statistically significant difference was found among the groups after this period. In conclusion, the use of a bonded maxillary expander to prevent unfavorable dentoskeletal changes in the vertical plane, in patients with long lower anterior face height, was not justified in this study since no significant differences were shown between the changes produced by the three appliances, in the postretention period.

Keywords: Rapid Maxillary Expansion. Palatal Expansion. Vertical Control.

Friday, May 03, 2024 07:11