Physiological positioning strategy alters condylar position after mandibular ramus sagittal split osteotomies for mandibular prognathism

Intraoperative condylar positioning techniques on mandible in orthognathic surgery

PURPOSE

The surgical condylar displacement often resulted in relapse and serious symptoms of temporomandibular joint disorders (TMD) after orthognathic surgery. To minimize the displacement, numerous techniques have been proposed. To verify their accuracy in positioning and effectiveness in preventing postoperative TMD and relapse, we reviewed the literature related to intraoperative condylar positioning techniques on the mandible in this study.

METHODS

The literature on condylar positioning techniques was reviewed with 2 charts, including the non-computer-assisted and the computer-assisted positioning methods. The pre- and postoperative alterations of condyles, the postoperative temporomandibular joint (TMJ) function, and surgical relapse were analyzed regarding the techniques. The clinical usage and characteristics were reviewed as well.

RESULTS

A total of 22 articles, including 907 patients, have been reported since 2001. Nearly all methods reach a considerable positioning accuracy within the range of 1-2 mm and 1-2° from the preoperative position. We ranked the accuracy of the methods from high to low: CAD/CAM CPDs>CAD/CAM titanium plate positioning>manual positioning>computer-assisted navigation systems>imaging positioning systems. Most skeletal class II and class III patients achieved great occlusion and had no TMJ dysfunction or relapse after condylar positioning.

CONCLUSION

Both the non-computer-assisted and computer-assisted condylar positioning techniques reach considerable accuracy in locating the preoperative condyle position and preventing TMJ dysfunction and surgical relapse. Different levels of surgeons and cases can benefit from multiple suggested positioning methods. Further research with large samples and long-term follow-up is worth looking forward to upgrading the current methods, improving the clinical utility, and developing new positioning techniques.

A new method for individual condylar osteotomy and repositioning guides used in patients with severe deformity secondary to condylar osteochondroma

Background

Mandibular condylar osteochondroma (OC) could lead to facial morphologic and functional disturbances, such as facial asymmetry, malocclusion, and temporomandibular joint dysfunction. However, after condylar OC resection, the inaccurate reposition of the neocondyle still needs to be solved. The purpose of this study was to explore the feasibility of the condylar osteotomy and repositioning guide to reposition the neocondyle in the treatment of patients with severe deformity secondary to condylar OC.

Results

Three patients with severe deformity secondary to OC of the mandibular condyle were enrolled in this study. With the aid of condylar osteotomy and repositioning guide, condylar OC resection and repositioning were carried out, and the accuracy and stability of these guides were evaluated. All patients healed uneventfully, and no facial nerve injury and condylar ankylosis occurred. Compared with the computerized tomography scans in centric relation before surgery and 3 days after surgery, the results showed that the facial symmetry was greatly improved in all the patients. Also, after the superimposition of the condylar segments before surgery and 3 days after surgery, the postoperative reconstructed condyles had a high degree of similarity to the reconstruction of the virtual surgical planning. Observed from the sagittal and coronal directions, the measurements of condylar positions were very close to those of virtual surgical planning. Moreover, it also showed stable results after a 1-year follow-up.

Conclusions

For patients with severe deformity secondary to condylar OC, condylar osteotomy, and repositioning guide was expected to provide a new option for the improvement of facial symmetry and occlusal relationship.

The outcome of skeletofacial reconstruction with mandibular rotation for management of asymmetric skeletal class III deformity: A three-dimensional computer-assisted investigation

The mandibular proximal ramus segments should be moved and rotated during orthognathic surgery-based skeletofacial reconstruction for the correction of challenging patients with facial asymmetry and malocclusion, but quantitative data regarding this rotation were not sufficient to date. This 3D computer-assisted study measured the proximal ramus segment rotation after 3D simulation-guided two-jaw surgery in patients with facial asymmetric deformity and class III malocclusion (n = 31). Using 3D mandible models and a reliable proximal ramus segment-related plane, angular changes in pitch, roll and yaw directions were measured before and one month after surgery. Significant rotational changes (p < 0.01) were observed in the left and right sides and overall proximal ramus segments after surgery, with absolute differences of 4.1 ± 3.0 (range −7.8 to 6.9), 2.8 ± 2.3 (−8.8 to 5.0), and 2.7 ± 2.4 (−6.6 to 9.9) degrees in pitch, roll, and yaw rotations, respectively. Numbness and mouth opening limiting occurred within the first 6 months after surgery but the patients had an unremarkable long-term postoperative course, with no revisionary surgery required. This study contributes to the multidisciplinary-related literature by revealing that proximal ramus segment rotation and rigid fixation with no postoperative intermaxillary immobilization was practicable in skeletofacial surgery for the successful treatment of asymmetric deformity and class III malocclusion.

Long-term skeletal stability in the treatment of mandibular prognathism with a physiological positioning strategy

Our aim was to evaluate the long-term skeletal stability of the mandible in 21 patients after orthognathic surgery with physiological positioning. The measurement points SNB, B point (X, Y), Pog (X, Y), and the angle of the ramus were measured on cephalometric photographs to assess skeletal stability preoperatively, immediately after operation, and one and two years postoperatively. In addition, we evaluated the clinical symptoms of disorders of the temporomandibular joint (TMJ). The analysis of the cephalometric photographs showed that SNB, B point X, and Pog X showed no significant differences among the postoperative time points. On the other hand, B point Y and Pog Y showed no significant differences throughout the study period. We compared the angle of the ramus before operation and two years postoperatively, and no significant difference was found. In addition, no cases showed any pathological symptoms of disorders of the TMJ two years postoperatively. The long-term stability after orthognathic surgery with physiological positioning was confirmed, and it seems to be a reliable orthognathic treatment in patients with mandibular prognathism.

Usefulness of Early Plate Removal in Patients With Occlusal Discrepancies After Sagittal Split Ramus Osteotomy

The aim of this study was to evaluate the effects of early removal of fixed plates in patients with occlusal discrepancies after sagittal split ramus osteotomy (SSRO) with a focus on the positional relationship of the temporomandibular joint (TMJ). Sagittal split ramus osteotomy with/without Le Fort I osteotomy was performed on 98 patients with mandibular prognathism. Of these 98 patients, 15 with occlusal discrepancies and/or TMJ symptoms underwent early plate removal after SSRO. Finally, 12 consecutive patients were evaluated in this study: 7 underwent bilateral SSRO, 1 underwent unilateral SSRO, and 4 underwent bilateral SSRO with maxillary advancement. The axiolateral TMJ Schuller method was used to evaluate the TMJ position. The authors measured 3 spaces (anterior, superior, and posterior joint spaces) between the condyle and glenoid fossa in the sagittal plane. The anterior and superior joint spaces were significantly larger immediately after the operation than before the operation. After early plate removal, these spaces significantly decreased in size. The posterior joint space increased, but with no significant difference. Three months after SSRO, the size of each of the 3 spaces was closely related to its preoperative size. In conclusion, these results suggest that early removal of fixed plates is 1 treatment option for postoperative occlusal discrepancies after SSRO.