A Prospective Study Comparing Adolescent and Post-Adolescent Periods Regarding Effects of Activator Appliance in Patients with Class II Mandibular Retrognathia by Using 3dMDface Analysis and Cephalometry

BACKGROUND: The purpose of this prospective study was to compare adolescent and post-adolescent growth periods regarding the effectiveness of conventional activator appliance in patients with Class II mandibular retrognathia by using lateral cephalometric radiographs and three-dimensional photogrammetry (3dMDface). MATERIAL/METHODS: We enrolled 2 groups: 15 patients in the adolescent growth period and 17 patients in the post-adolescent growth period. All patients had Class II anomaly with mandibular retrognathia and were treated with conventional activator appliances. Lateral cephalometric radiographs and three-dimensional photogrammetric views were obtained at the beginning and end of the activator treatment of Class II patients. Maxillomandibular discrepancy, mandibular protrusion and lengths, convexity angles, facial heights, and dental measurements were evaluated cephalometrically. Projections of the lips and the chin and volumetric measurements of the lip and the mandibular area were assessed using three-dimensional photogrammetry. RESULTS: Conventional activator therapy resulted in similar effects in both growth periods regarding improvements in the mandibular sagittal growth and maxillomandibular relationship (ANB° and the SNB° angles). Mandibular effective length was increased (Co-Gn length) and the maxillary horizontal growth was restricted (decreased SNA° angle) in both groups following the treatment. Treatment duration was significantly longer in the post-adolescent group. Increases in the projections of menton, pogonion, and sublabial points were observed in the three-dimensional photogrammetric views. Total lip volume was reduced while the mandibular volume was significantly increased in both groups. Lower gonial angle showed a greater increase in the post-adolescent group. CONCLUSIONS: Correction of Class II anomaly with mandibular retrognathia was achieved with a combination of dental and skeletal changes in both growth periods. Conventional activator therapy may be an alternative treatment approach in the late growth period as it led to significant skeletal and dental changes.