Copyright © 2016 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited. Assessment of the Postoperative Stability of Mandibular Orthognathic Surgery for Correction of Class III Skeletal Malocclusion Giuliano Henrique Mia ˜o Luchi, PhD,  Ricardo Augusto Conci, PhD, y Flavio Henrique Silveira Tomazi, MSc, z Rosana da Silva Berticelli, PhD, § Michel Martins Guarenti, MSc,  Guilherme Genehr Fritscher, PhD, z and Cla ´iton Heitz, PhD z Abstract: To assess the stability of mandible position after orthog- nathic 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 treat- ment for elimination of dental compensations followed by com- bined 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 cranio- metric landmark measurements showed that the precision of man- dibular 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. Key Words: Class III skeletal malocclusion, lateral cephalograms, orthognathic surgery (J Craniofac Surg 2017;28: 151–156) O rthognathic surgery is increasingly recognized as a safe procedure with predictable outcomes. Improvement of oper- ative techniques, development of new fixation devices, and deter- mination of normal standards of facial anatomy using numerical data have minimized postoperative relapse issues and made orthog- nathic surgery a viable adjunct for the correction of dentofacial deformities in adults. 1–7 One of the various skeletal deformities in which surgical ortho- dontic intervention is indicated is class III skeletal malocclusion, which may be due to maxillary retrusion, mandibular protrusion, or a combination of both, and jeopardized facial harmony and sto- matognathic function. 8,9 Integrating adequate preoperative plan- ning, precise orthodontic preparation, planned osteotomies, and aesthetic plastic surgery techniques, orthognathic surgery is a corrective cosmetic procedure that can provide normal occlusion and restore a pleasing balance of facial harmony. 9 The accuracy of this procedure is ensured by a protocol that consists of several technical steps performed prior to the actual surgery and should be followed in each patient. 4–6 Now, as patients secure ever greater access to this therapeutic option for the correction of malocclusions (including class III patients), 5 the present study was designed to assess the stability of mandibular positioning after orthognathic surgery through an analysis of lateral cephalograms obtained immediately before surgery, immediately after surgery, and at 6- month follow-up. METHODS Approval for the study was obtained from the Pontifical Catholic University of Rio Grande do Sul (PUCRS) Research Ethics Com- mittee (judgment no. 990/11). The authors have also read the Helsinki Declaration and have followed its guidelines in this investigation. Patient data were used in accordance with Brazilian Ministry of Health regulations as set forth in National Health Council Resolution 196/96 of October 10, 1996. The study sample comprised 20 adult males with Angle class III skeletal malocclusion, aged 18 to 40 years, recruited from the outpatient clinic of the PUCRS Graduate Program in Oral and Maxillofacial Surgery and Traumatology (FO/PUCRS). Patients were included in the study only if they had no local or systemic contraindications to orthognathic surgery. Patients with craniofacial deformities or syndromes were excluded from the study, as were those with cleft lip or palate. All patients underwent adequate orthodontic care preoperatively (to ensure proper alignment of the dental arches and eliminate any dental compensation, improving the position of the teeth within the bone) and postoperatively (to refine the occlusal result). Surgical treatment consisted of bilateral sagittal split osteotomy for man- dibular setback, followed by rigid internal fixation with three 2.0- mm bicortical screws, and Le Fort I osteotomy of the maxilla followed by 2.0-mm miniplate fixation with monocortical screws at the canine and zygomatic buttresses. All patients were operated on by the same team of surgeons. Lateral cephalograms were obtained preoperatively (T0), immediately after the procedure (T1), and at least 6 months after surgery (T2). The mean length of follow-up was 27 months (range, 5–63 months). All cephalograms were obtained at the FO/PUCRS Radiology Service using a Siemens Orthophos CD (serial no. From the  Post-Graduate Program in Dentistry, Grupo Hospitalar Conceic ¸a ˜o, Porto Alegre; y Post-Graduate Program in Dentistry, State University of West Parana, Cascavel; z Post-Graduate Program in Den- tistry, Pontifı ´cia Universidade Cato ´ lica do Rio Grande do Sul (PUCRS), Porto Alegre; and § Post-Graduate Program in Dentistry, State University of West Parana, Cascavel, Brazil. Received May 19, 2016. Accepted for publication September 16, 2016. Address correspondence and reprint requests to Ricardo Augusto Conci, PhD, Universitaria Street, 1619, Jardim Universitario, 85819-110. Cascavel, PR, Brazil; E-mail: ricardo_conci@hotmail.com The authors report no conflicts of interest. Copyright # 2016 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000003311 ORIGINAL ARTICLE The Journal of Craniofacial Surgery  Volume 28, Number 1, January 2017 151