A retrospective study in comparison of skeletal stability and pharyngeal airway changes in mandibular prognathism after correction with mandibular setback surgery using two different types of osteofixation materials

Abstract

Objectives: This study compared the skeletal stability and pharyngeal airway changes after mandibular setback procedure using the titanium and resorbable plate and screws fixation.

Materials and Methods: 28 patients with mandibular prognathism being treated with bilateral sagittal split ramus osteotomy (BSSRO) were randomly selected from titanium and resorbable fixations. Analyses of lateral cephalometric x-rays were performed according to preoperative (T0), 1st week post-surgery (T1), 3-6 months post-surgery (T2) and 1-year post-surgery (T3). The horizontal measurement (BX), vertical measurement (BY), and angle measurement (SNB and Mandibular Plane Angle; MPA) were studied for skeletal stability. The pharyngeal airway changes were observed by nasopharynx (NOP), uvula (UOP), tongue (TOP) and epiglottis (EOP).

Results: There were no significant difference of mandibular setback in titanium (6.61±3.97 mm.) and resorbable groups (5.08±3.21 mm.). Significant MPA changes were found in both titanium and resorbable groups in 3-6 months post-surgery, but MPA still expressed significant changes in the resorbable group in 1-year post-surgery (2.29±0.59; p-value=0.006). The resorbable group was found significant EOP changes (-1.21±0.3 mm; p-value=0.02) in 3-6 months post-surgery, then gradually returned to no significant changes in 1-year post-surgery.

Conclusion: This study could be demonstrated that osteofixation with resorbable plates and screws was comparable to titanium in long-term pharyngeal airway dimension, but a tendency to relapse, particularly mandibular plane angle.