Assessment of the Postoperative Stability of Mandibular Orthognathic Surgery for Correction of Class III Skeletal Malocclusion

Abstract

To assess the stability of mandible position after orthognathic surgery for correction of class III skeletal malocclusion. Twenty adult males, aged 18 to 40 years, with Angle class III skeletal malocclusion underwent preoperative orthodontic treatment for elimination of dental compensations followed by combined maxillomandibular surgery with rigid internal fixation. Lateral cephalograms from each patient, obtained in the natural head position before surgery, immediately after surgery, and at 6-month follow-up, were retrieved from the files of the Pontifical Catholic University of Rio Grande do Sul outpatient Oral and Maxillofacial Surgery clinic and compared. Comparison of craniometric landmark measurements showed that the precision of mandibular setback was compromised in the horizontal plane, with a mean mandibular relapse of 37.75% at point B and 45.85% at point Pg. Improved intercuspation and adaptation of the musculature to the new position of the jaws after orthognathic surgery lead to counterclockwise rotation of the mandible, ultimately displacing the mandible more anteriorly than desired.

Assessment of Masseter Volume and Postoperative Stability After Orthognathic Surgery in Patients With Skeletal Class III Malocclusion With Facial Asymmetry

“…In our study, during the postoperative period, the patients had better maxillary stability, whereas the mandibles exhibited slight upward and anterior displacement ( P < 0.05). This is also consistent with the results of many studies on postoperative stability after Orthognathic Surgery, counterclockwise rotation of the mandible is due to improved intercuspation and adaptation of the musculature to the new position of the jaws, ultimately leading to the mandible more anteriorly than expected 16 …”

“…This is also consistent with the results of many studies on postoperative stability after Orthognathic Surgery, counterclockwise rotation of the mandible is due to improved intercuspation and adaptation of the musculature to the new position of the jaws, ultimately leading to the mandible more anteriorly than expected. 16 It has been shown that males are more prone to recurrence than females after orthognathic surgery, 17 and the thickness of the masseter in males is significantly higher than that in females, 18 and in our study, we found that the volume of the masseter was significantly greater in male than in female patients. Recurrence of mandibular retraction is partly caused by masticatory muscle factors, so we suspect that postoperative stability is related to masseter volume, and to the best of our knowledge, there are no studies that have examined the relationship between occlusal muscle volume and postoperative recurrence.…”