Comparing Soft Tissue Outcomes in Skeletal Class II Malocclusion: Anterior Segmental Osteotomy vs. Non-Surgical Orthodontic Treatment

Objectives: Temporary anchorage devices (TAD) has reduced the need for anterior segmental osteotomy (ASO) in patients with Class I malocclusion. Previous studies were mostly published before the widespread use of TADs. Therefore, new guidelines are required to determine the optimal approach between surgery and orthodontic treatment. The purpose of this study is to establish guidelines on the choice between ASO and non-ASO (NASO) based on soft tissue considerations. Materials and Methods : Sixty-seven patients diagnosed with skeletal Class II malocclusion were divided into ASO (n = 31) and NASO (n = 36) groups. Cephalometric analyses were used to compare the initial and final records to assess the impact of treatment on soft tissue. The interlabial gap, upper lip to E-line, lower lip to E-line, H-angle, UL to N-perpendicular line, and nasolabial angle were evaluated. Specially a proportional difference indicator between the upper and lower lips relative to the Pog (CKHA) was presented, followed by statistics analyses. A P-value of less than 0.05 indicated statistical significance. Results: Both groups showed normal proportion between the upper and lower lips, although significant differences favoring ASO over NASO in soft tissue changes were observed in several variables. Conclusions: If the required adjustment for the upper and lower lips is -4.0 mm and -5.0 mm, respectively, ASO is advised. For modifications of -2.0 mm, NASO is preferred. Clinical Relevance: This study provides clinical guideline for choosing between ASO and NASO treatments based on required lip movement measurements.