Does maxillomandibular fixation affect skeletal stability following mandibular advancement? A single-blind clinical trial

Abstract

Background The stability of the results remains a significant concern in orthognathic surgeries. This study aimed to assess the amount of relapse following mandibular advancement with/without maxillomandibular fixation (MMF). Materials and methods A single-blind clinical trial was conducted on patients with mandibular retrognathism who underwent BSSO for mandibular advancement and Lefort I maxillary superior repositioning. Patients were randomly divided into two groups of treatment (MMF) and control (no MMF). In the treatment group, MMF was performed for 2 weeks; meanwhile, MMF was not performed in the control group, and only guiding elastics were applied postoperatively. Lateral cephalograms were obtained preoperatively (T1), immediately after surgery (T2), and at 1 year postoperatively (T3). The distance from points A and B to the X and Y plane were measured to identify the amount of vertical and horizontal relapse in 1 year as a primary outcome. An independent t-test was applied in order to find differences in outcomes between the control and treatment groups. Results Fifty-eight patients were evaluated in two groups (28 patients in the MMF group and 30 in the no-MMF group). The magnitude of mandibular advancement following BSSO was 7.68±1.39 mm and 7.53±1.28, respectively, without significant difference among the groups (p= 0.68). The mean sagittal and vertical changes (relapse) at point B were significantly different between the two groups at 1-year follow-up after the osteotomy (p=0.001 and p=0.05, respectively). Conclusion According to the results of this study, patients with short-term MMF following BSSO for mandibular advancement benefit from significantly greater skeletal stability in the sagittal and vertical dimensions.

Orthodontic-surgical treatment for severe skeletal class II malocclusion with vertical maxillary excess and four premolars extraction: A case report

“…For this patient’s orthognathic surgery, impacting the maxilla surgically allowed the mandible to rotate upward and forward. It has been well documented that the Lefort I down fracture technique with superior repositioning has excellent stability[ 21 ]. Furthermore, the forward movement of the mandible contributed to this patient’s successful treatment and improved profile.…”

A finite element analysis of stress distribution with various directions of intermaxillary fixation using orthodontic mini‐implants and elastics following mandibular advancement with a bilateral sagittal split ramus osteotomy

“…Furthermore, it provides less stress on the temporomandibular joint (TMJ) and causes less nerve damage and relapse than the bicortical screw method. 4,5,9 IMF [14][15][16][17][18][19][20][21][22][23][24][25][26] after RIF is a necessary procedure that holds the surgically corrected intermaxillary relationships and helps to prevent skeletal relapse. Orthodontic surgical archwires with soldered or crimpable hooks and intermaxillary elastics or wiring have been used with a surgical splint for IMF.…”

“…23 In addition, there are problems with this method because the position of the hooks cannot be controlled, and there is the possibility of bracket detachment. 24 To overcome these problems, bone screws [15][16][17][18][19]22,24,25 or orthodontic MIs 20,21,23,26 have been applied for IMF. IMF screws can be placed in various sites, but some authors suggest that the best position is between the canine and first premolar, 15,22 and just a single IMF screw in each quadrant is sufficient.…”

“…24 To overcome these problems, bone screws [15][16][17][18][19]22,24,25 or orthodontic MIs 20,21,23,26 have been applied for IMF. IMF screws can be placed in various sites, but some authors suggest that the best position is between the canine and first premolar, 15,22 and just a single IMF screw in each quadrant is sufficient. 15 IMF screws have both minuses and pluses.…”

“…20,23,26 An IMF elastic force of about 150 g is applied in various directions depending on the position of the IMF screws, thus directing the vector of the IMF elastic force. 14,15,17,[20][21][22][23][24] Several finite element analysis (FEA) studies [27][28][29][30][31] have evaluated the stress distribution on the bone and fixation system according to different RIF methods after BSSRO for mandibular advancement. However, no study has investigated the stress patterns on the osteotomy and fixation sites with various directions of the IMF.…”