Cephalometric study through lateral cephalograms of dentoskeletal changes following by the use of three maxillary expansion appliances: bonded, Haas and Hyrax / Estudo cefalométrico em norma lateral das alterações dentoesqueléticas produzidas por três tipos de expansores: colado, tipo Haas e Hyrax

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

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. The sample consisted of 69 lateral cephalograms taken from 23 subjects, 15 females and 8 males, with an initial age ranging from 9 years 8 months to 15 years 5 months, presenting uni or bilateral posterior crossbite, that underwent rapid maxillary expansion with a bonded maxillary expander with a full occlusal acrylic coverage. The lateral cephalograms were taken before treatment (pre-expansion), immediately after expansion and three months after retention with the same appliance. The results were compared to a previous study of the Haas and Hyrax expanders in 41 subjects, 26 females and 15 males, with an initial age ranging from 10 years 8 months to 17 years 8 months, with uni or bilateral posterior crossbite. The lateral cephalograms were taken at the same time intervals as the first group. 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 displacements. 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, which was more significant in the groups I and II, while the lower anterior face height underwent a statistically significant increase, similarly 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.

ASSUNTO(S)

expansores maxilares cefalometria em odontologia alterações dentoesqueléticas

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