Efeitos imediatos da expansão rápida da maxila no sentido transversal, com os disjuntores tipo Haas e Hyrax, em tomografia computadorizada cone beam

• Ano de defesa: 2008
• Autor(a) principal: Weissheimer, André
• Orientador(a): Menezes, Luciane Macedo de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ODONTOLOGIA; ORTODONTIA; TÉCNICA DE EXPANSÃO PALATINA
• Link de acesso: http://hdl.handle.net/10923/552

The purpose of this prospective study was to evaluate and compare, quantitatively, the immediate effects of rapid maxillary expansion in the transverse plane, with the tooth tissue-born (Haas-type) and tooth-born (Hyrax) expanders, in cone-beam computed tomography. A sample of 33 subjects (11 boys e 22 girls; mean age, 10 years and 9 months), with transverse maxillary deficiency, were randomly divided into two groups: (1) Haas group with 18 subjects and (2) Hyrax group with 15 subjects. All patients were subjected to rapid maxillary expansion protocol with initial activation of four-quarter turn (0. 8 mm), followed by two-quarter turn (0. 4 mm) daily up to the expansion screw reach 8 mm. Cone-beam computed tomography were taken before expansion (T1) and at the end of active expansion phase (T2). Skeletal, dentoalveolar and dental measurements were compared by using mixed analysis of variance model and Tukey-Kramer method, at a significance level of 5%. The results showed significant (p<0. 0001) increase in all skeletal, dentoalveolar and dental dimensions of the maxilla in transverse plane. In general, skeletal expansion was smaller in the posterior region, accounting for 30 a 41,5 % of screw activation, compared to anterior region, where the increases accounted for 43,5 a 50%. The Hyrax expander produced greater immediate skeletal effect in the transverse dimension of maxilla than the Haas-type expander.The expansion in dentoalveolar region accounted, in general, for 70,2% of screw activation, and there were no significant differences between the two expanders. Dental expansion accounted for 97,5% of screw activation, with the first permanent molars showing significant (p<0. 0001) buccal tipping, mean of 7,53 degrees in the right side and 6. 17 degrees in the left side. The Haas-type expander had greater significant tendency to tip the first permanent molars buccally than Hyrax expander (p=0. 0008).