Evaluation of the stability of treatment with Herbst appliance associated with Hyrax expander and fixed orthodontics through counterpart analysis: A longitudinal follow‐up study

摘要

Abstract Objective The aim of this study was to evaluate the stability of treatment with a Herbst appliance associated with Hyrax expander (Stage I), followed by fixed appliances (Stage II) and follow‐up for an average of 4?years after Stage II, on dentoskeletal facial structures. Methods This study involved 50 adolescents with Angle Class II division 1 malocclusion associated with mandibular retrognathism: Treated Group (TG‐25) and Control Group (CG‐25). Lateral cephalometric radiographs were taken: T1, immediately before Stage I (TG) or at the beginning of the follow‐up period (CG); T2, at the end of Stage I (TG) or the follow‐up period (CG); T3, at the end of Stage II (TG); and T4, on average, 4?years after Stage II (TG). Enlow's counterpart analysis and some cephalometric measurements were evaluated. Parametric and non‐parametric tests were used (P?≤?0.05). Results The ramus alignment variables (P??T2??T2?=?T3?=?T4; 1.MP, P??T2?=?T3?=?T4 and S‐LI, P?=?0.003, T1?=?T2?=?T3?>?T4. Conclusion The nasomaxillary complex (MCF/PM alignment) tended to a retrusive effect to compensate the degree of mandibular retrusion. The protrusive effect of the lower facial third was evident after the Herbst stage and did not remain stable in the follow‐up. The dentoalveolar compensation and improvement in facial profile remained stable.