Abstract Objective Maxillary molar distalization with intraoral distalizer appliances is a non-extraction orthodontic treatment used to correct molar relationship in patients with Class II malocclusion presenting maxillary dentoalveolar protrusion and minor skeletal discrepancies. This study compares the changes caused by three distalizers with different force systems. Methodology 71 patients, divided into three groups, were included. The Jones jig group (JJG, n=30; 16 male, 14 female, 13.17 years mean age) was treated with the Jones jig for 0.8 years. The Distal jet group (DJG, n=25; 8 male, 17 female, 12.57 years mean age) was treated with the Distal jet for 1.06 years. The First Class group (FCG, n=16; 6 male, 10 female, 12.84 years mean age) was treated with the First Class for 0.69 years. Intergroup treatment changes were compared using one-way ANOVA, followed by post-hoc Tukey’s tests. Results Intergroup comparisons showed significantly greater maxillary incisor protrusion in DJG than in FCG (2.56±2.24 mm vs. 0.74±1.39mm, p=0.015). The maxillary first premolars showed progressive and significantly smaller mesial angulation in JJG, FCG and DJG, respectively (14.65±6.31º, 8.43±3.99º, 0.97±3.16º; p<0.001). They also showed greater mesialization in JJG than FCG (3.76±1.46 mm vs. 2.27±1.47 mm, p=0.010), and greater extrusion in DJG compared to JJG (0.90±0.77 mm vs 0.11±0.60 mm, p=0.004). The maxillary second premolars showed progressive and significantly smaller mesial angulation and mesialization in JJG, FCG and DJG, respectively (12.77±5.78º, 3.20±3.94º, -2.12±3.71º and 3.87±1.34 mm, 2.25±1.40 mm, 1.24±1.26 mm, respectively; p<0.001). DJG showed smaller distal angulation of maxillary first molars (-2.14±5.09º vs. -7.73±4.28º and -6.05±3.76º, for the JJG and FCG, respectively; p<0.001) and greater maxillary second molars extrusion (1.17±1.41 mm vs -0.02±1.16 mm and 0.16±1.40 mm, for the JJG and FCG, respectively; p=0.003). Overjet change was significantly larger in DJG compared to FCG (1.79±1.67 mm vs 0.68±0.84; p=0.046). Treatment time was smaller in FCG (0.69±0.22 years vs 0.81±0.33 years and 1.06±0.42 years, comparing it with the JJG and DJG, respectively; p=0.005). Conclusion The three appliances corrected the Class II molar relationship by dentoalveolar changes. The Distal jet produced smaller molar distal angulation than the Jones jig and First Class. The First Class appliance showed less anchorage loss, greater percentage of distalization and shorter treatment time than the Jones jig and Distal jet.

RESUMO Objetivo: o presente estudo avaliou os efeitos dentoesqueléticos e tegumentares em pacientes com má oclusão de Classe II tratados com aparelho Distal Jet, comparando-os com um grupo controle não tratado. Métodos: 44 pacientes com má oclusão de Classe II foram divididos em dois grupos: Grupo 1 (experimental) - 22 pacientes, idade média de 12,7 anos, tratados com o aparelho Distal Jet por um período médio de 1,2 anos; Grupo 2 (controle) - 22 pacientes não tratados, idade média de 12,2 anos, acompanhados por um período médio de 1,2 anos. Telerradiografias laterais foram obtidas antes do tratamento (T0) e no final da distalização (T1). O teste t independente foi usado para identificar as diferenças entre os grupos. Resultados: quando comparado ao grupo controle, o Distal Jet produziu um aumento significativo no ângulo do plano mandibular (0,7 ± 2,0o). Os segundos molares superiores apresentaram inclinação distal (6,6 ± 3,8o), distalização (1,1 ± 1,1 mm) e extrusão (1,3 ± 2,1 mm). Os primeiros molares superiores foram distalizados por 1,2 ± 1,4 mm. Os primeiros pré-molares superiores, mesializados por 3,4 ± 1,1 mm. Os incisivos superiores mostraram leve inclinação labial de 4,3 ± 4,7o e foram protruídos por 2,4 ± 1,7 mm. Não existiram alterações significativas no perfil facial. O overjet aumentou 1,5 ± 1,1 mm, e o overbite não sofreu alterações significativas. Conclusão: o aparelho Distal Jet é eficaz para distalizar os primeiros molares superiores, mas promove aumento no ângulo do plano mandibular, inclinação distal, extrusão e distalização dos segundos molares superiores, mesialização dos primeiros pré-molares superiores, vestibularização e protrusão dos incisivos superiores e aumento do overjet, quando comparado a um grupo de controle.

ABSTRACT Objective: This study evaluated the dental, skeletal and soft tissue effects in Class II malocclusion patients treated with Distal Jet appliance, compared to an untreated control group. Methods: 44 patients with Class II malocclusion were divided into two groups: Group 1 (experimental) - 22 patients, mean age of 12.7 years, treated with the Distal Jet appliance for a mean period of 1.2 years; Group 2 (control) - 22 untreated patients, mean age of 12.2 years, followed by a mean period of 1.2 years. Lateral cephalograms were obtained before treatment (T0) and at the end of the distalization (T1).Independent t test was used to identify intergroup differences. Results: When compared to control group, the Distal Jet produced a significant increase in mandibular plane angle (0.7 ± 2.0o). The maxillary second molars presented distal inclination (6.6 ± 3.8o), distalization (1.1 ± 1.1 mm) and extrusion (1.3 ± 2.1 mm). The maxillary first molars distalized by 1.2 ± 1.4 mm. The maxillary first premolars mesialized by 3.4 ± 1.1 mm. The maxillary incisors showed slight labial tipping of 4.3 ± 4.7o and were protruded by 2.4 ± 1.7 mm. There were no significant changes in the facial profile. The overjet increased 1.5 ± 1.1 mm and overbite had no significant changes. Conclusion: The Distal Jet appliance is effective to distalize the maxillary first molars, but promotes increase in mandibular plane angle, distal inclination, extrusion and distalization of maxillary second molars, mesialization of maxillary first premolars, proclination and protrusion of maxillary incisors, and increase in overjet, when compared to a control group.