Contenção ortodôntica na estabilidade transversal dental e esquelética da maxila apos expansão rápida assistida cirurgicamente (ERMAC)

Abstract

Introdução: A expansao rapida da maxila assistida cirurgicamente (ERMAC) e o procedimento de escolha para tratamento de adultos com defiCiência transversal da maxila maior que 5 mm. A estabilidade dos resultados apos ERMAC ainda nao esta bem esclarecida assim como a necessidade do uso das contencoes apos a remocao do aparelho expansor. Objetivo: Avaliar o efeito da contencao ortodontica na estabilidade transversal dental e esqueletica da maxila, apos ERMAC. Metodos: Foram avaliados 90 modelos de gesso digitalizados de 30 pacientes adultos,18 masculinos e 12 femininos submetidos a ERMAC utilizando aparelho expansor do tipo Hyrax. Os pacientes foram distribuidos em dois grupos: Grupo Sem Contencao (GSC) n= 15; e Grupo Com Contencao (GCC) n=15. No GCC foi instalado um Arco Transpalatino (ATP) como contencao logo apos a remocao do expansor. Os modelos de gesso foram realizados nos periodos: pre-operatorio (T1); aos quatro meses, quando o expansor foi removido (T2) e dez meses apos o termino da expansao (T3). Todos os modelos de gesso foram digitalizados com escaner a laser 3D Vivid 9i (Konica Minolta, Wayne, NJ). Foram avaliadas as medidas: distancias Inter-Cuspides de Pre-Molares e Molares (Inter-Cusp PM) (Inter-Cusp M), Inter- Colo de Pre-Molares e Molares (Inter-Colo PM) (Inter-Colo M), Inter- Borda WALA de Pre-Molares e Molares (Inter-BW PM) (Inter-BW M), altura do palato no molar, area e volume do palato nos tempos T1, T2 e T3. Resultados: Ocorreu um aumento medio significante de todas as variaveis aos quatro meses em relacao aos valores preoperatorios (p<0,05), exceto para a altura do palato que apresentou uma diminuicao significante nesse periodo (p<0,001). A unica variavel que apresentou comportamento diferente entre os grupos aos dez meses foi adistancia Inter-Cusp PM, sendo no GSC a recidiva de 1,84 mm (5,4%) (p<0,001) e esta nao foi observada no GCC (p>0,999). Para as demais variaveis nao houve diferenca entre os grupos sendo as recidivas medias apos dez meses (T3) em ambos os grupos de 0,95 mm (2,99%) na distancia Inter- Colo PM; 0,88 mm (1,75%) na distancia Inter-BW PM, 1,04 mm (2,35%) para distancia Inter- Colo PM, 1,04 mm (2,05%) Inter-BW PM 1,04mm(2,92%)Inter-Cusp M; 0,74 mm (1,9%) na distancia Inter-Colo M e 0,84 mm (1,34%) na Inter-BW M (p<0,05). As medidas da altura, area e volume do palato se mantiveram estaveis apos 10 meses em ambos os grupos (p>0,05). Conclusao: A contencao ortodontica impede a recidiva dental na regiao de pre-molares e nao e necessaria para evitar as recidivas dentais na regiao de molares e ossea na regiao de pre-molares e molares apos (ERMAC)

Introduction: Surgically Assisted Rapid Maxillary Expansion (SARME) is the procedure of choice for treatment of adults with transverse maxillary deficiency greater than 5 mm. The stability of the results after SARME is not yet well established, as well the need to use retainers after removal of the expander. Objective: To evaluate the effect of the orthodontic retainer on transverse maxillary dental and skeletal stability after SARME. Methods: Ninety digitized dental casts of 30 adult patients (18 males and 12 females) submitted to SARME using the Hyrax expansion appliance were evaluated. Patients were distributed into two groups: Group Without Retention (GSC) n = 15; and Group With Retention (GCC) n = 15. In the GCC group, a Transpalatal Arch (TPA) was installed for retention soon after removal of the expander. The dental casts were scanned using a Vivid 9i 3D laser scanner (Konica Minolta, Wayne, NJ). The plaster models were performed preoperatively (T1), 4 months after the expander was removed (T2), and 10 months after the end of the expansion (T3). The distances measured were Inter-Cusps of Premolars and Molars (Inter-Cusp PM) (Inter-Cusp M), Inter-Cervicals of Premolars and Molars (Inter-Cervical PM) (Inter-Cervical M), Inter-WALA edges of Premolars and Molars (PM Inter-BW) (BW Inter-M), palatal height at the molar, and palatal area and volume at T1, T2, and T3. Results: There was an significant average increase of all variables signi at four months compared to pre-operative values (p <0.05), except for the palatal height that showed a significant decrease in this period (p <0.001). The only variable that showed a different behavior between the groups at ten months was the distance InterCusp PM. The GSC mean relapse was 1.84 mm (5.4%) (p <0.001) and this was not observed in the GCC (p> 0.999). The other variables did not differ Abstract | 134 between the groups being the average relapse after ten months (T3) in both groups of 0.95 mm (2.99%) in the distance Inter-Colo PM, 0.88 mm (1.75 %) in the distance BW Inter-AM, 1.04 mm (2.35%) for inter-distance Cusp M, 0.74 mm (1.9%) in the Inter-Colo distance M and 0.84 mm (1 34%) in Inter-M BW (p <0.05). Measurements of height, area and volume of the palate remained stable after 10 months in both groups (p> 0.05). Conclusions: Orthodontic retention prevents dental relapse in the region of the premolars and is not necessary to avoid dental relapse in the molar region and skeletal relapse in the premolar and molar region after SARME.