Three- dimensional analysis of transverse width of hard tissue and soft tissue after mandibular setback surgery using intraoral vertical ramus osteotomy : a retrospective study

Publication date: Available online 18 October 2018

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Sang Hyun Song, Jun-Young Kim, Sung Hwa Lee, Jin Hoo Park, Hwi-Dong Jung, Young-Soo Jung

Abstract

Purpose

Some clinicians are concerned that if an intraoral vertical ramus osteotomy (IVRO) is used to position the mandible posteriorly, the proximal segments should be positioned laterally to the distal segment, which could increase the transverse mandibular width (TMW), leading to esthetically-unfavorable results. This study investigated short- and long-term postoperative TMW changes in soft and hard tissue following IVRO for mandibular prognathism .

Methods

The subjects were 44 patients who were treated with mandibular setback surgery using an IVRO. They were categorized into either of a "facial symmetry" or "facial asymmetry" group based on their preoperative levels of chin top deviation. Three dimensional cone-beam computed tomography images were obtained at the preoperative, 1 and 12-month postoperative stages as T1, T2, and T3, respectively. We set the hard tissue-1 (HW1) and HW2 as the sum of distance at the bilateral ends of the angle and ramus; soft tissue-1 (SW1) and SW2 as the sum of distance at the bilateral ends of the soft tissue angle and ramus.

Results

Compared to the value at T1, the HW1 value increased by 8.16% (P<0.05) and HW2 increased by 4.39% (P>0.05) at T2; HW1 increased by 4.35% (P<0.05) and HW2 by 2.95% (P>0.05) at T3.

Compared to the value at T1, the SW1 value increased by 2.49% and SW2 increased by 2.50% at T2; however, SW1 decreased by 0.85% and SW2 increased by 0.37% at T3. The soft-tissue variations between T1 and T2, as well as between T2 and T3, were statistically significant. However, no significant difference was found between T1 and T3 (P>0.05) There was no difference between the facially symmetric and asymmetric groups over time for soft and hard tissues (P>0.05).

Conclusion

Notably, IVRO does not seem to impact the transverse facial profile and enables reliable prediction of the esthetic results of surgery.

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