Bilateral Sagittal Split Osteotomies vs Mandibular Distraction Osteogenesis

Objectives: Bilateral sagittal split osteotomies (BSSO) and bilateral mandibular distraction osteogenesis (BMDO) have both been applied in the surgical treatment of Class II mandibular hypoplasia.  For advancements between 6-10mm, there has yet to be any comparison of which method is more stable.  BSSO have also been reported to be associated with a high incidence of neurosensory disturbance of the interior alveolar nerve (IAN) when compared with studies on mandibular distraction.  This randomized controlled trial aims to compare the stability and morbidities of both techniques for mandibular advancements between 6-10mm.

Methods: 40 Class II mandibular hypoplasia patients requiring mandibular advancement of 6-10mm were randomized into 2 groups of either BSSO or BMDO.  Serial lateral cephalographs were taken at post-operative periods 2 weeks , 6 weeks , 12 weeks, 6 months 12 months  and 24 months.  Skeletal stability using specific cephalometric landmarks were assessed at the respective post-operative periods.  Objective neurosensory evaluation was performed and any post-operative complications recorded.  The paired t-test was used to analyze stability and neurosensory scores with statistical significance set at p<0.05.

Results: There was no statistically significant difference (P>0.05) in horizontal skeletal stability between the two groups at all time points. Post-operative complications included anterior open bite (BSSO=1, BMDO=0), posterior open bite (BSSO=1, BMDO = 1), wound infection (BSSO=2, BMDO=4) and condylar resorption (BSSO=2, BMDO=1)

Conclusions: Skeletal stability and post-operative complications seem to be comparable between BSSO and BMDO for advancements between 6-10mm.  Both groups reported elevated objective neurosensory scores in the early post-operative period.