Three-dimensional soft tissue comparison in non-growing patients treated for skeletal Class II Division I malocclusion: Mandibular advancement surgery vs. Herbst Appliance

Abstract

OBJECTIVE: This study used three-dimensional (3D) stereophotogrammetry to compare changes in facial soft tissues of patients with skeletal class II malocclusion with mandibular retrognathia treated with orthognathic surgery (OS) or Herbst appliance (HA). METHODOLOGY: This retrospective study included 15 adults treated with bilateral sagittal split osteotomy without genioplasty (OS) and 16 adults treated with HA. The patients were treated successfully, with class I occlusal relationships with normal overjet and overbite. Three-dimensional stereophotogrammetric records acquired in habitual occlusion from before and after fixed orthodontic treatment were analyzed. Lateral cephalometric radiographs were used to evaluate skeletal parameters and sagittal oropharyngeal airway length. RESULTS: In HA-group, mandibular corpus length, anterior facial height, posterior facial height, Bº, vertical angle, and mentolabial angle increased; lower facial width, mandibular angle, mandibular convexity angle, ANBº, and Aº decreased. In OS-group, mandibular length, mandibular corpus length, and facial convexity angle increased significantly compared with those in HA-group; posterior facial height, Bº, vertical angle, and mentolabial angle also increased, but mandibular angle and ANBº decreased significantly. Only a significant difference in coordinate changes was observed for the pogonion in the sagittal direction. According to the cephalometric analysis, SNBº and Pg-NA perpendicular measurements increased significantly in the OS group compared with the HA group. In both groups, sagittal oropharyngeal airway length increased significantly post-treatment, with no significant intergroup difference. CONCLUSION: In patients treated with OS, skeletal advancement resulted in greater increases in mandibular and corpus lengths, along with forward positioning of the pogonion. Based on 3D soft tissue and cephalometric comparisons, the Herbst appliance seems to be a viable non-surgical alternative for young adults with moderate Class II malocclusion. Both treatment modalities also contributed to significant improvements in sagittal oropharyngeal airway length.