Oral and maxillofacial surgery
Changes in the temporomandibular joint disc position after orthognathic surgery

https://doi.org/10.1016/j.tripleo.2009.02.005Get rights and content

Objective

This clinical research was carried out to investigate the influences of orthognathic surgery on the temporomandibular joint (TMJ) using magnetic resonance imaging (MRI) taken before and after the surgery.

Study design

There were 23 subjects who had a bilateral sagittal split ramus osteotomy in Seoul National University Bundang Hospital from June 2004 to December 2006 and their condyles. The mean age of patients was 22.09 ± 3.65 and the number of men and women was 10 and 13, respectively. Bilateral sagittal planes of 46 condyles had taken MRI in both closed and open mouth states before and 3 months after surgery. The differences between pre- and postoperative disc positions and internal disc derangement (IDD) stages were evaluated. Furthermore, a correlation analysis of the amounts of mandibular set-back and disc positions was carried out. Paired-samples of the T tests, the McNemar-Bowker test and Pearson correlation analysis were applied as statistical methods. In this study, a significance level is considered to be less than 0.05.

Results

The disc positions had not shown statistically significant differences between pre- and post-operation in the closed state. However there were significant increases of distances between the discs and condyle on mouth opening. For instance, 0.70 ± 1.30 mm was an average (P < .01). The derangement stages of each condyle were not changed through the operation. Although there were improved or aggravated cases, the orthognathic surgery had no influence on derangement stages in this study. Last, there was no significant correlation between the 2 variables of the amounts of set-back and the changes of disc position.

Conclusions

Although there were significant differences of the disc positions in the open mouth state, the orthognathic surgery appears not to have had an effect on the TMJ.

Section snippets

Materials and Methods

This research was approved by the Institutional Review Board at Seoul National University, Bundang Hospital. Patients agreed to this study. Patients had no clinical symptom including mouth opening limitation, TMJ pain, and so forth. But detailed clinical signs and symptoms relating to TMD before and after surgery were not evaluated.

Of the patients with mandibular prognathism who underwent bilateral mandibular sagittal split ramus osteotomy at the Department of Oral and Maxillofacial Surgery of

Results

The sagittal images of bilateral mandible were analyzed in all patients. This showed that the distance between mandibular condyle and articular disc in mouth opening was 1.74 ± 2.13 mm preoperatively and 2.44 ± 2.10 mm postoperatively. That is, the distance between mandibular condyle and articular disc was significantly increased by 0.70 ± 1.30 mm on average following orthognathic surgery (P < .01). In mouth closing, the location of articular disc had a mean change of −0.11 ± 1.46 mm; however,

Discussion

According to one of the representative orthognathic surgeries, BSSRO can induce the change in the location of mandibular condyle and the displacement of articular disc. However, there is still a controversy as to whether or not orthognathic surgery has an effect on the TMJ. For instance, some studies have reported that the specific symptoms and signs of TMD were improved following the surgical correction of maxillofacial deformity (TMD). Other studies have reported that there was no significant

Conclusions

In our series, the location of the articular disc according to a specific mouth opening demonstrated a signficant change on preoperative and postoperative MRI scans. However, when comprehensively analyzing these results, the location of the articular disc and stage of internal disc derangement did not greatly vary in the mouth closing phase. Moreover, the amount of mandibular setback did not have a big effect on the changes of the location of articular disc.

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This study was supported by grant no 11-2008-014 from the SNUBH Research Fund.

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