Lateral cephalometric changes and stability of BSSO versus IVRO for mandibular setback surgery: A systematic review and meta-analysis.

The aim of this review is to examine the lateral cephalometric hard tissue changes and the stability of the end result of bilateral sagittal split osteotomy (BSSO) and the intraoral vertical ramus osteotomy (IVRO) techniques for mandibular setback surgery. A systematic review of MEDLINE (via PubMed), Scopus, and Cochrane Library databases (last search date: August 22nd, 2021) was performed according to the PRISMA guidelines. Only studies that directly compare BSSO and IVRO were included. Random-effects model meta-analyses were performed. Ten studies, comprising a total of 331 patients, 169 patients undergoing BSSO and 162 patients undergoing IVRO were identified. No statistically significant differences were observed regarding the angular measurements: Sella/Nasion/B point (SNB) angle post-operatively (standardized mean difference [SMD]= 0.39, 95% Confidence Interval [CI]: [-0.15] – [0.94], p=0.16, I2=57.09%) and 1 year after surgery (SMD= 0.72, 95% CI: [-0.08] – [1.53], p=0.08, I2=80.83%), gonial angle post-operatively (SMD=0.45, 95% CI: [-0,26] – [1.15], p=0.21, I2=72.54) and 1 year after surgery (SMD= 0.15, 95% CI: [-0.79] – [1.08], p=0.75, I2=91.56%), and MP angle 1 year after surgery (SMD=-0.46, 95% CI: [-1.64] – [0.72], p=0.45, I2=90.81%). In addition, no statistically significant differences were observed regarding the linear measurements, the relapse of the mandible as measured by the relapse of B point 1 year after surgery in the horizontal axis (SMD= 0.73, 95% CI: [-0.25] – [1.72], p=0.15, I2=86.43%) and vertically (SMD= -0.76, 95% CI: [-1.97] – [0.45], p=0.22, I2=90.09%). BSSO and IVRO have similar results in terms of SNB and gonial angle relapse post-operatively and 1 year after surgery, MP angle 1 year after surgery and horizontal and vertical relapse, measured in reference to B point 1 year after surgery.