A new appliance for condylar positioning (clamp system)

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.

Three-dimensional assessment of condylar position following orthognathic surgery using the centric relation bite and the ramal reference line: A retrospective clinical study

Orthognathic surgery (OGS) is a relatively common procedure for solving functional and aesthetic problems in facial and jaw areas in patients with dentofacial deformities. The positioning of the mandibular condylar segment during OGS has an impact on the surgical outcome. This study aimed to investigate the changes in the condyle-fossa relationship three dimensionally after OGS using the centric relation (CR) bite and the ramal reference line (RRL).Thirty-two patients with skeletal malocclusion underwent OGS. Condylar repositioning was performed using the CR bite, as previously reported. A RRL was added to the existing method and used during the surgery. Cone-beam computed tomography scans were acquired at 4 time points. Sixty-four condyles were evaluated in the coronal, sagittal, and axial views. Two groups were created according to the amount of mandible setback (SB1 vs SB2), and another 2 groups were created according to the maxillary operation (1-jaw vs 2-jaw). Each was then compared at the 4 time points. Differences between the values before (T0) and a year after surgery (T3) were also investigated. The positions of the pogonion and the menton were examined at T2 and T3 for the simple evaluation of relapse.The change in the condylar position was significant over a time-course (P < .001) but not between T0 and T3 (P > .05). Neither the setback amount nor the maxillary operation affected the positional change (P > .05). There were no significant changes between T2 and T3 in the relapse evaluation.This condylar repositioning method using the CR bite and a RRL showed stable results after OGS. This method is noninvasive and cost-effective and can be easily performed even by an inexperienced surgeon because it reduces errors in repositioning the condyle during OGS.

MRI changes in the temporomandibular joint following mandibular setback surgery using sagittal split ramus osteotomy with rigid fixation

OBJECTIVES

This study examined the changes in temporomandibular joint dysfunction (TMD) symptoms and investigated the variations in the disc position, disc and condylar morphology following sagittal split ramus osteotomy (SSRO) with rigid fixation in patients with mandibular prognathism. Furthermore, the authors examined the correlation between mandibular setback and TMD symptoms.

METHODS

The study included 24 Japanese patients with jaw deformities who were treated using bilateral SSRO and Le Fort I osteotomy. The clinical and magnetic resonance imaging findings in the temporomandibular joint were evaluated preoperatively and at three and six months postoperatively.

RESULTS

The preoperative TMD symptoms were significantly associated with the prevalence of TMD symptoms at six months postoperatively. Anterior disc displacement improved in four joints with slight displacement and with no morphological change. There were no postoperative changes in condylar morphology. There was no significant correlation between mandibular setback and the postoperative TMD symptoms.

CONCLUSION

Postoperative TMD symptoms may be influenced mainly by preoperative TMD symptoms rather than mandibular setback using SSRO with rigid fixation. Therefore, patients with TMD symptoms require physical examination and MRI for appropriate diagnosis preoperatively.

The assessment of the stability in mandibular setback surgery related to spatial factors under rotational control of the proximal segment

OBJECTIVE

To evaluate the surgical relapse of mandibular setback, related to the magnitude of setback and LeFort I osteotomy under rotational control of the proximal segment.

STUDY DESIGN

Data from 78 patients who had undergone sagittal split ramus osteotomy for mandibular prognathism were reviewed. The stability of the proximal segment was retrospectively confirmed. Serial cephalograms were used to assess relapse over 1 year. The association between relapse and LeFort I osteotomy as well as the magnitude of setback was assessed.

RESULTS

Minimal counterclockwise rotation was noted postoperatively, but the proximal segment remained stable for 1 year. Notable forward relapse was shown in the setback of more than 7 mm (P < .01) with resumption of function after 6 weeks, but it was not related with LeFort I osteotomy.

CONCLUSIONS

Relapse was related to the amount of setback and occurred on resumption of function despite rotational control of the proximal segment.

Change in condylar long axis and skeletal stability following sagittal split ramus osteotomy and intraoral vertical ramus osteotomy for mandibular prognathia

PURPOSE

The purpose of this study was to compare postsurgical time course changes in condylar long axis and skeletal stability between sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO).

PATIENTS AND METHODS

Of 40 Japanese patients with a diagnosed jaw deformity, 20 underwent IVRO without internal fixation and 20 underwent SSRO with rigid internal fixation. The time course change in condylar long axis and skeletal stability were assessed with axial, frontal, and lateral cephalograms.

RESULTS

A significant difference in the rotation direction of condylar long axis was seen in horizontal axial cephalogram images (P <.01). In Pog-N perpendicular to SN, the IVRO group showed gradual decrease, although SSRO group showed gradual increase in lateral cephalogram (P <.05).

CONCLUSION

The present results suggest a significant difference between SSRO and IVRO in time course changes in proximal segment including condyle and distal segment.

Changes in bite force and dentoskeletal morphology in prognathic patients after orthognathic surgery

OBJECTIVE

We sought to evaluate the changes in bite force and dentoskeletal morphology in prognathic patients after orthognathic surgery.

STUDY DESIGN

Twenty-four patients underwent orthognathic surgery to correct Class III skeletal and dental malocclusions. Ten patients who underwent Le Fort I and bilateral sagittal split ramus osteotomy of the mandible (ie, surgical correction of 2 jaws) and 14 patients who underwent only bilateral sagittal split ramus osteotomy (ie, surgical correction of 1 jaw) were compared. Bite force was measured preoperatively and at 3, 6, and 12 months postoperatively. The dentoskeletal morphology was assessed through lateral cephalograms obtained preoperatively and 12 months postoperatively.

RESULTS

Twelve months postoperatively, the bite force was significantly greater in the patients who underwent surgery on 1 jaw than in the patients who underwent surgery on 2 jaws. Significant decreases in the gonial angle, occlusal plane angle, and anterior facial height were observed postoperatively in the patients with 1 surgically corrected jaw, but not in the patients with 2 surgically corrected jaws. Patients with 2 surgically corrected jaws experienced a greater increase in the Frankfort mandibular plane angle and a greater decrease in the posterior facial height than did those with 1 surgically corrected jaw.

CONCLUSION

The difference in the preoperative-to-postoperative change in dentoskeletal morphology between the 2 groups is one of the factors responsible for the significant difference in postoperative bite force between the 2 groups.

Changes in bite force and occlusal contact area after orthognathic surgery for correction of mandibular prognathism

OBJECTIVE

This study examined the long-term changes of bite force and occlusal contact area in patients with prognathous after orthognathic surgery with a newly developed pressure-sensitive sheet (Dental-Prescale; Fuji Photo Film Co).

STUDY DESIGN

Fifty-seven patients with prognathous were examined. Bite force and occlusal contact area were measured just before operation and at 2 weeks, 1 month, 3 months, 6 months, 1 year, 2 years, and 3 years after operation. Forty control subjects with normal occlusion were also measured.

RESULTS

The bite force and occlusal contact area of the patients were significantly greater than the preoperative level at 1 year, 2 years, and 3 years after operation. However, they were still significantly lower than the control subject level even at 3 years after operation.

CONCLUSIONS

This study suggests that orthognathic surgery improves the bite force and occlusal contact area of patients with prognathous. However, at 3 years from the time of operation, patients had not reached control subject levels.

Postoperative stability after sagittal split ramus osteotomy with condylar-positioning appliance and screw fixation: asymmetric versus symmetric cases

OBJECTIVE

The purpose of this study was to evaluate postoperative stability in prognathic patients with mandibular asymmetry who were treated with sagittal split ramus osteotomy of the mandible.

STUDY DESIGN

Ten asymmetric (group I) and 11 symmetric (group II) patients were examined. An appliance for repositioning the proximal segment was applied, and the bony segments were fixed with titanium screws. Cephalograms were obtained preoperatively, 2 to 3 days postoperatively, and 3 and 6 months after surgery. Changes in the positions of the standard points were examined on lateral cephalograms, and changes in the widths of the gonion points were examined on posteroanterior cephalograms.

RESULTS

Statistical analysis revealed no significant difference between the two groups. In addition, there was no significant difference between the postoperative changes in the widths of the gonion points on the deviated and nondeviated sides in group I.

CONCLUSIONS

This study suggests that application of an appliance for repositioning the proximal segment can minimize postoperative skeletal changes in patients with asymmetry.

Stability after surgical correction of mandibular prognathism using the sagittal split ramus osteotomy and fixation with poly-L-lactic acid (PLLA) screws

PURPOSE

This study was designed to examine skeletal stability after surgical correction of mandibular prognathism using a sagittal split ramus osteotomy (SSRO) and fixation with poly-L-lactic acid (PLLA) screws.

PATIENTS AND METHODS

Twenty patients with Class III malocclusion were treated with bilateral SSRO and mandibular setback. Ten underwent fixation with titanium screws (group I) and the other 10 with PLLA screws (group II). Cephalograms were obtained 2 or 3 days postoperatively, and at 3, 6, and 12 months after the operation. Changes in the position of upper incisors (U-1), lower incisors (L-1), B-point, and pogonion were examined on lateral cephalograms.

RESULTS

Certain tendencies for overjet and overbite were noted to have decreased more markedly, and changes in the position of the skeletal points were greater in group II than in group I. However, statistical analysis showed no significant differences between the two groups.

CONCLUSION

Our results suggest that fixation of the bony segments with PLLA screws after SSRO may be used effectively in properly selected cases.

A new condylar positioning appliance for two-jaw osteotomies (Le Fort I and sagittal split ramus osteotomy)

We have presented a new appliance for easy, rapid, and exact repositioning of the proximal segment of the mandible in two-jaw osteotomies (Le Fort I and sagittal split ramus osteotomy).