Treatment modalities of TMJ ankylosis: experience in Delta Nile,Egypt

The study reports the authors’ experience in managing TMJ ankylosis in Delta Nile, Egypt (1995–2006) and compares the surgical modalities used. 101 patients (109 joints) were reviewed in this retrospective study. Pre- and postoperative assessment included history, radiological and physical examination, and mouth opening. Age, sex, aetiology, joint(s) affected, surgical modality, complications and follow up periods were evaluated. Various types (fibrous, fibro-osseous and bony) of TMJ ankylosis were diagnosed; trauma was the commonest aetiology. The patients’ age range was 2–41 years, 62% were female, and the follow up period ranged from 14 to 96 months. Average mouth opening was significantly increased from 5.3 mm pre-operatively to 32.9 mm 12 months postoperatively (P = 0.0001). Marked improvement in mouth opening was documented when the ramus-joint complex was reconstructed using distraction osteogenesis (34.7 mm), costochondral graft (34.4 mm) and Surgibone (34.6 mm). Gap arthroplasty showed least satisfactory mouth opening compared with other techniques (P = 0.001). Minor and major complications were encountered in 33% of cases, including 5% recurrence rate. Early release of TMJ ankylosis; reconstruction of the ramus height with distraction osteogenesis or bone grafting combined with interpositional arthroplasty, followed by vigorous physiotherapy is successful for managing TMJ ankylosis.     

Complaints related to mandibular function impairment after closed treatment of fractures of the mandibular condyle

This study analysed the relationship between complaints and mandibular function after closed treatment of fractures of the mandibular condyle in a prospective study. In a 1-year follow-up, complaints were assessed during physical examination and function was assessed using the mandibular function impairment questionnaire (MFIQ), scoring range 0–68. Data from 114 patients (41 women, 73 men), mean age 28.1 years (SD 13.3), were available. On average the MFIQ scores were low 3.4 (SD 7.3). Ten patients (9%) experienced pain and 45 (39%) patients had a MFIQ score > 0. Mean mouth opening was 51.9 mm (SD 8.4). Occlusion was perceived as moderate or poor by 24% of the patients. In the logistic regression analysis mandibular function impairment (MFIQ score > 0) was entered as a dependent variable. Risk factors for mandibular function impairment were: pain, perceived occlusion (moderate or poor), absolute difference between left and right horizontal movements and age. A protective factor was mouth opening. The results of this study show that complaints (i.e. pain, perceived occlusion, reduced mouth opening, difference between left and right lateral movements and increased age) are predictors of mandibular function impairment after closed treatment of fractures of the mandibular condyle.     

Grafts of autogenous coronoid process to reconstruct the mandibular condyle in children with unilateral ankylosis of the temporomandibular joint: long-term effects on mandibular growth

Injury to the mandibular condyle in children usually leads to malocclusion and disharmony of facial growth. Our aim was to study the facial growth after reconstruction of the mandibular condyle using autogenous coronoid process grafts in children with unilateral ankylosis of the temporomandibular joint (TMJ). We followed up 10 growing patients with unilateral bony ankylosis of the TMJ who had been admitted to the West China Hospital of Stomatology, Sichuan University (Chengdu, China) between 1 January 2008 and 31 December 2012. There were three boys and seven girls, age range 5–12 years at the time of operation. In each case, patients were treated by gap arthroplasty, reconstruction of the condyle with an ipsilateral coronoid process, and interposition of the pedicled temporalis fascial flap during one operation. The mean (range) postoperative follow up was 4.73 (3–6) years. Postoperative panoramic radiographs were taken, and the growth of the mandibular height and length on the affected side was measured and compared with the healthy side. All patients had an uneventful, normal recovery. The mean (range) maximal mouth opening at the end of follow up was 35.6 (32–41) mm. Both the height of the ramus and the length of the mandible continued to grow after successful treatment of the ankylosis (using autogenous coronoid process grafts for reconstruction of the condyle) but the deficit in growth was not completely made up. The final height of the ramus on the affected side (at the end of follow up) had increased by 25% (p = 0.012) and the final length of the mandible on the affected side by 26% (p = 0.010) compared with immediately after operation. For comparison of the rate of growth, the increased height of the ramus of the affected side was 47% lower (p = 0.003), while the increased length of the mandible on the affected side was 27% shorter (p = 0.008) compared with the healthy side. The mandible on the affected side continued to grow after successful treatment of the ankylosis, but the growth deficit was not made up completely. The rate of growth of the affected mandible seemed to be less than on the undisturbed side even after treatment of the ankylosis.     

Preservation of condyle and disc in the surgical treatment of type III temporomandibular joint ankylosis: a long-term follow-up clinical study of 111 joints

The purpose of this study was to establish the role of retaining the condyle and disc in the treatment of type III ankylosis, by clinical and computed tomography (CT) evaluation. A total of 90 patients with type III ankylosis met the inclusion criteria; 42 patients had left temporomandibular joint (TMJ) ankylosis, 27 patients had right TMJ ankylosis, and 21 had bilateral TMJ ankylosis, thus a total 111 joints were treated. Considerable improvements in mandibular movement and maximum mouth opening were noted in all patients. At the end of a minimum follow-up of 2 years, the mean inter-incisal mouth opening was 30.7 mm. Postoperative occlusion was normal in all patients, and open bite did not occur in any case because the ramus height was maintained through preservation of the pseudo-joint. Only three patients had recurrence of ankylosis, which was due to a lack of postoperative physiotherapy. The advantages of condyle and disc preservation in type III ankylosis are: (1) surgery is relatively safe; (2) the disc helps to prevent recurrence of ankylosis; (3) the existing ramus height is maintained; (4) the growth site is preserved; and (5) there is no need to reconstruct the joint with autogenous or alloplastic material. It is recommended that the disc and condyle are preserved in type III TMJ ankylosis.     

Evaluating the remodeling of condyles reconstructed by transport distraction osteogenesis in the treatment of temporomandibular joint ankylosis

PurposeThis study aimed to evaluate the remodeling of condyles reconstructed by transport distraction osteogenesis (DO) in patients with temporomandibular joint (TMJ) ankylosis.Patients and methodsTwenty-one patients with 26 affected joints were followed up for 34.1 ± 13.3 months. Patients who had undergone gap arthroplasty and TMJ reconstruction by DO were included. Maximal mouth opening (MMO) and occlusion were recorded. Computed tomography images were obtained preoperatively (T0), upon completing distraction (T1), upon removal of the distraction device (T2), and >2 years postoperatively (T3). The following were measured: mandibular ramus height, distance between gonion and Frankfurt plane (Go–FN), condylar width, and condyle–ramus angulation.ResultsOf the 21 patients, one showed re-ankylosis, while five exhibited anterior open bite. From T1 to T3, the total amount of resorption of ramus height reached up to 8.2 ± 4.6 mm (p < 0.001), in comparison with a total distraction length of 13.8 ± 4.1 mm; the mean resorption rate was 59.4%. Similarly, Go–FN decreased by 6.2 ± 4.0 mm (p < 0.001).ConclusionOur findings indicated that DO combined with gap arthroplasty was an effective method for the treatment of TMJ ankylosis to improve MMO. The reconstructed condyle exhibited a high frequency of resorption in height.     

Simultaneous arthroplasty and distraction osteogenesis for the treatment of ankylosis of the temporomandibular joint and secondary mandibular deformities in children

The purpose of this study was to explore the use of simultaneous arthroplasty and distraction osteogenesis in the treatment of children with ankylosis of the temporomandibular joint (TMJ) and secondary mandibular deformities. Between January 2012 and December 2016, 17 children (7 boys and 10 girls, mean (range) age 7 (4–12) years) were treated. Preoperatively, the mean (range) maximal incisal opening was 1.4 (0–5) mm. Distraction osteogenesis was used to elongate the mandibular body or ramus, or both, after the release of ankylosis. Distraction began after five to seven days at a rate of 0.5 mm twice daily, and the distractor was removed three to five months after the completion of distraction. The mean (range) follow-up time after removal was 29.6 (16–45) months, and the distance of distraction was 14.4 (10–18) mm. After treatment, all patients had satisfactory outcomes, a good facial profile, alignment of the midline lower incisor, and a level occlusal plane. The mean (range) maximum incisal opening reached 35.7 (31–41) mm. Bone formation across the distraction gap was good. The mean minimum axial area of the airway increased from 61.4 mm to 96.4 mm (p < 0.01). No patients had a recurrence of ankylosis during follow up. Our results suggest that simultaneous arthroplasty and distraction osteogenesis is feasible in this group.     

Condylar positions before and after bilateral mandibular distraction osteogenesis in children with Pierre Robin sequence

This study aimed to analyze the changes in mandibular morphology after bilateral mandibular distraction osteogenesis (BMDO) in children with Pierre Robin sequence. The positions of the condyles were analyzed in reconstructed three-dimensional craniomaxillofacial images obtained for 18 children before and 8–12 weeks after BMDO. Differences between pre- and postoperative parameters were assessed using paired t-tests. After surgery, a significant decrease in superior joint space was detected (P < 0.05), but no change in anterior joint space or posterior joint space was observed. The ratio of the distance between gonia and distance between condylion points (GoL–GoR/CoL–CoR) (P < 0.001) and the distances between the condyle and midsagittal plane (P < 0.001) increased after surgery, while the condylar horizontal angle decreased (P < 0.05). No change in condylar vertical angle was noted. After BMDO, the condyle displayed an outward and upward shift, as well as outward rotation along the proximal segment. The mandible body exhibited forward movement with a more significant opening range. These changes were consistent with the extent of the newly formed bone tissue and the improvement in coordination and appearance of the children’s facial structures. The long-term effects of changes in condylar position on the development of the maxillofacial structures needs to be studied further.     

Treatment of chronic mandibular dislocations using miniplates: follow-up of 8 cases and literature review

Temporomandibular joint (TMJ) dislocation is an excessive forward movement of the condyle beyond the articular eminence with complete separation of the articular surfaces and fixation in that position. This study reports 8 cases using miniplates for chronic mandibular dislocations, evaluates the results and critically reviews the literature. The sample was obtained from the records of the Oswaldo Cruz University Hospital and comprises patients undergoing chronic mandibular dislocation treatment using 2.0 mm titanium miniplates between August 2002 and March 2004. Pre- and postoperative assessment included a thorough history and physical examination to determine the maximal mouth opening, presence of pain and sounds, frequency of luxations, recurrence rate and presence of facial nerve paralysis. The mean maximal mouth opening preoperatively was 42.75 ± 11.53 mm and was 45.62 ± 8.52 mm postoperatively. There was no facial nerve paralysis. Miniplate fracture was observed in 2 cases and there was one recurrence. Treating chronic mandibular dislocation using miniplates was shown to be efficient in relation to postoperative maximal mouth opening, recurrence and articular function, however, the possibility of the miniplate fracturing must be considered.     

The sequential treatment of temporomandibular joint ankylosis with secondary deformities by distraction osteogenesis and arthroplasty or TMJ reconstruction

The purpose of this study was to evaluate the sequential treatment of patients with temporomandibular joint (TMJ) ankylosis and secondary deformities by distraction osteogenesis and subsequent arthroplasty or TMJ reconstruction. This study included 40 patients treated at a stomatological hospital in China; they ranged in age from 9 to 53 years (mean age 24.5 years). Ten of these patients were diagnosed with unilateral TMJ ankylosis and 30 with bilateral TMJ ankylosis. Twenty-seven patients also presented obstructive sleep apnoea–hypopnoea syndrome (OSAHS). All patients underwent distraction osteogenesis as the initial surgery, followed by arthroplasty or TMJ reconstruction. Some patients underwent orthognathic surgery to improve occlusion and face shape along with or after arthroplasty or TMJ reconstruction. The therapeutic effects were evaluated in terms of the improvements in maximum inter-incisal opening (MIO), appearance, and respiratory function. After the completion of treatment, all patients showed improvements in MIO and appearance, and the symptom of snoring disappeared. The airway space was significantly increased. Patient follow-up ranged from 6 to 85 months (mean 28.3 months), and four patients experienced relapse. This study suggests that treating TMJ ankylosis with secondary deformities by distraction osteogenesis as the initial surgery and arthroplasty or TMJ reconstruction as the second-stage treatment may achieve favourable outcomes, especially for patients with OSAHS; however, some patients may require orthognathic surgery.     

Evaluating the correlation between the lateral pterygoid muscle attachment type and internal derangement of the temporomandibular joint with an emphasis on MR imaging findings

ObjectivesDisc displacement is accepted as one of major findings in temporomandibular disorders. Correlation between lateral pterygoid muscle (LPM) attachment type to the disc–condyle complex and TMJ dysfunction has rarely been discussed and still not clarified. The purpose of this study was to assess the prevalence LPM attachment type to the disc–condyle complex, and to investigate whether these attachment types are linked to MR imaging findings of ID and TMJ dysfunction in a Turkish population.Study designNinety-eight TMJs in 49 patients (32 males, 17 females, mean age = 36 years) with one of either: TMJ clicking, TMJ locking, restricted movement of the jaw, or pain in the TMJ region, were included. According to the clinical findings and data obtained from MRI examinations, TMJs dysfunctions were classified. LPM attachments to the condyle–disc complex were categorized into three different types. Correlation between TMJ dysfunction and LPM attachments to the condyle–disc complex was evaluated.ResultsOf 98 TMJs in 49 patients (32 males, 17 females, mean age = 36 years), 47 TMJ’s (%48) were evaluated as normal, 35 (%35.7) had a disc displacement with reduction and 16 (%16.3) TMJ had a disc displacement without reduction. Arthritis was seen in 49 TMJ’s (%50). LPM attachments to the condyle–disc complex were as follows: Type I (29.6%), Type II (40.8%), and Type III (29.6%). There was no statistically significant difference between the type of muscle attachment and the presence or absence of disc displacement (p = 0.481), disc degeneration (p = 0.752), articular surface degeneration (p = 0.117).ConclusionsThere was no statistically significant correlation between the LPM attachment types and TMJ abnormalities.     

Two-step transport-disk distraction osteogenesis in reconstruction of mandibular defect involving body and ramus

One-step transport-disk distraction osteogenesis (TDDO) is effective for repairing segmental mandibular defects. The authors studied whether it was effective for reconstructing angled large mandibular defects using a two-step TDDO procedure in seven patients suffering from neoplasm. In the two-step TDDO procedure, the first distraction (horizontal distraction) was initiated immediately after mandibulectomy, aimed at restoring the mandibular body. It was followed by the second distraction, which was obliquely vertical and aimed at restoring the height of the ramus. The distraction rate was set at twice 0.4 mm/day. The treatment lasted for 14–18 months. The horizontal distraction length ranged from 48 to 55 mm, and the vertical one from 33 to 43 mm, with full ossification in the distraction area. No obvious shift of mandible, malocclusion or mouth opening limitation was observed. Patients had a regular diet and spoke clearly. In conclusion, the two-step TDDO is still an option for the reconstruction of large angled mandibular defects when patients are prudently selected, despite the long treatment period required.     

Groningen temporomandibular total joint prosthesis: An 8-year longitudinal follow-up on function and pain

Total temporomandibular joint replacement is a surgical procedure for patients with severe temporomandibular joint afflictions affecting quality of life, which have not responded beneficially to previous conventional surgery. The aim of this study was to assess the long-term outcome of the Groningen temporomandibular joint (TMJ) prosthesis in patients with chronic pain and mutilated temporomandibular joints following multiple surgical procedures, with respect to prosthesis failure, the patient's postoperative level of satisfaction and longitudinal changes in maximum mouth opening, functional mandibular impairment and pain. Eight female patients were studied in whom Groningen TMJ prostheses were inserted, two unilaterally and six bilaterally.The Groningen TMJ prosthesis was mechanically successful during 8 years of follow-up in seven out of eight patients with a disc dislocation being seen in one patient (7%). Patients were satisfied, despite the limited improvement of the maximum mouth opening, and pain scores.Although the decline of MFIQ scores during 8 years of follow-up was significant compared to baseline (p = 0.027), the effects of the prosthesis on maximum mouth opening, function and pain were limited. This may be due to persistent chronic pain and the adverse effects of multiple previous surgical procedures.     

Is dermis fat arthroplasty better than plain gap arthroplasty? A prospective randomised controlled trial

The aim of the study was to compare interpositional arthroplasty using a dermis fat graft with gap arthroplasty in the management of ankylosis of the temporomandibular joint (TMJ). We organised a prospective randomised study of 22 patients who presented with ankylosis of the TMJ. They were randomised to be treated with either plain gap arthroplasty or dermis fat arthroplasty, and the predictor variable was the method of treatment. The primary outcome variables were mouth opening and pain on jaw exercises. Pain and interincisal opening were measured on day 5, day 14, at the end of one month, and at six months, one year, two years, and three years. There was a significant difference between the two groups on two occasions: postoperative day 5 (p = 0.013) and at one year (p = 0.018). The mean (SD) scores for mouth-opening were higher in the dermis fat group at all times (41.20 (4.69) mm compared with 39.50 (2.46) mm in gap arthroplasty at two years, and 41.40 (3.60) mm compared with 38.9 (2.02) mm at three years). The visual analogue pain scores were also lower in the dermis fat graft group. The groups showed similar results at the end of three years follow up, with no significant difference in mouth opening. We conclude therefore that the two techniques have similar outcomes in the management of ankylosis of the TMJ.     

Assessment of condylar changes after orthognathic surgery using computed tomography regional superimposition

This study aimed to investigate the effects of bimaxillary advancement orthognathic surgery on the condylar remodeling of the temporomandibular joint (TMJ) using voxel-based regional superimposition of cone-beam computed tomography (CBCT).In this retrospective study, the sample comprised 56 condyles from 28 healthy patients (aged from 16 to 50 years) with mandibular retrognathism treated with bimaxillary advancement. CBCT scans were taken preoperatively and at 14.3 ± 4.2 months postoperatively. The scans at the two time points were superimposed using regional voxel-based registration to assess condylar changes in the follow-up period. The linear alterations were measured in six different areas of each condyle to determine the pattern of condylar remodeling.Although no significant correlation was observed between changes in condylar surfaces, bone resorption occurred predominantly in the posterior and superior regions, while bone formation was predominantly on the anterior surface. Medial and lateral surfaces presented fewer bone changes. The overall bone changes were smaller than 1 mm bilaterally in 21 patients (75%) and, considering each condyle individually, were smaller than 1 mm in 48 condyles (85.7%).The results suggested that mild condylar remodeling in healthy patients is a common finding after orthognathic surgery. Future studies may clarify the mechanisms involved in the remodeling and help to understand the reasons for the remodeling pattern.     

Quantitative bone SPECT analysis of mandibular condyles in an asymptomatic population: an approach to normal reference values

Bone scintigraphy is an extremely valuable technique in diagnosis and treatment planning for patients with condylar hyperplasia (CH). The main objective of this study was to develop an approach to determine normal activity values in the mandibular condyles, adjusted to age and sex, through quantitative analysis of bone single-photon emission computed tomography (SPECT) on a condyle-by-condyle basis and to compare these values with those of a control group comprising patients with confirmed CH. Technetium 99 m-methylene diphosphonate (^99mTc-MDP) SPECT studies of the mandibular condyles were performed in patients with no mandibular pathology for quantitative analysis. Regions of interest were drawn on slices representing the upper, middle, and inferior thirds of each condyle and on the summation of transaxial slices representing the whole condyle (three-dimensional approach). The clivus was used for internal validation and the condyle to clivus ratios were calculated. These ratios were compared between ‘normal’ and ‘diseased’ condyles. A total 144 condyles in normal patients and 25 in confirmed CH patients were analysed. Differences between the ratios were evaluated through the coefficient of variation. In normal patients, the ratios to the clivus on the summed condyle image showed the lowest variability: range 0.3–1.28 (median 0.74). The quantile regression model showed significant differences with respect to sex, but not to age. The Mann–Whitney test showed significant differences in the ratios to clivus between normal and diseased condyles (P < 0.0001).     

Comparison of different analytical methods used for analyzing SPECT scans of patients with unilateral condylar hyperactivity

This study aimed to compare different analytical methods and identify the optimal analysis method to distinguish patients with unilateral condylar hyperactivity (UCH) from those with inactive condyles. Single-photon emission computed tomography (SPECT) scans of patients with progressive and nonprogressive mandibular asymmetry (each group, n = 26), were analyzed using the region of interest technique. Sensitivity, specificity and receiver operating characteristic (ROC) curves were calculated for the different analytic methods. The ROC curve illustrates that UCH can be diagnosed significantly better by determining the percentile bone activity in both condyles. The area under the curve (AUC) of the percentile comparison between the affected and contralateral condyles was 0.93 ± 0.04, that for the condyle/clivus ratio was 0.75 ± 0.07 and for the condyle/cervical spine (CS) ratio 0.57 ± 0.08. Sensitivity for the condyle/clivus ratio was 65% and specificity 61%. Sensitivity for the condyle/CS ratio was 85% and specificity 31%. For the percentile difference of the condyles, sensitivity and specificity were 88%. For UCH patients, direct comparison of bone activity between the affected and contralateral condyle in SPECT scans is the analysis method of choice. Comparison of condylar bone activity to reference bone activity does not have additional value in the diagnosis of UCH.     

Endoscopically assisted fixation of the custom-made total temporomandibular joint prosthesis in TMJ Yang’s system through a modified preauricular approach

This article describes the experience with the endoscopically assisted fixation of the customized total temporomandibular joint (TMJ) prosthesis in TMJ Yang’s system only through a modified preauricular approach. Twenty patients (23 joints) treated with the custom-made total TMJ prosthesis were retrospectively recruited. An endoscopically assisted technique was used through a modified preauricular approach to fix the mandibular component for all these patients. These reconstructions were evaluated by surgical records, clinical examinations, and radiographic observations. All patients had successful fixation of the prosthesis. No patient had permanent weakness of the facial nerve and malocclusion or any other severe complications. The mean operative time was 111 min per joint (range, 85–133 min). The average surgical bleeding was 195 ml per side. The mean follow-up period was 16.2 months (range, 5–32 months). The mean scores were 8.3 for surgical satisfaction and 9.2 for scar healing evaluation. All patients experienced positive clinical outcomes, with a mean 75.2% reduction in pain and 53.7% increase in mouth opening with significant differences (P < 0.05). The endoscopically assisted TMJ reconstruction with the customized prosthesis in TMJ Yang’s system through the modified preauricular approach could produce good aesthetic and functional results.     

Effects of four treatment strategies for temporomandibular joint closed lock

A previous randomized controlled trial (RCT) by Schiffman et al. (2007)¹⁵ compared four treatments strategies for temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock). In this parallel group RCT, 106 patients with magnetic resonance imaging (MRI)-confirmed TMJ closed lock were randomized between medical management, non-surgical rehabilitation, arthroscopic surgery, and arthroplasty. Surgical groups also received rehabilitation post-surgically. The current paper reassesses the effectiveness of these four treatment strategies using outcome measures recommended by the International Association of Oral and Maxillofacial Surgeons (IAOMS). Clinical assessments at baseline and at follow-up (3, 6, 12, 18, 24, and 60 months) included intensity and frequency of TMJ pain, mandibular range of motion, TMJ sounds, and impairment of chewing. TMJ MRIs were performed at baseline and 24 months, and TMJ tomograms at baseline, 24 and 60 months. Most IAOMS recommended outcome measures improved significantly over time (P ≤ 0.0003). There was no difference between treatment strategies relative to any treatment outcome at any follow-up (P ≥ 0.16). Patient self-assessment of treatment success correlated with their ability to eat, with pain-free opening ≥35 mm, and with reduced pain intensity. Given no difference between treatment strategies, non-surgical treatment should be employed for TMJ closed lock before considering surgery.     

Temporomandibular joint bony ankylosis: comparison of treatment with transport distraction osteogenesis or the matthews device arthroplasty

Temporomandibular joint (TMJ) bony ankylosis with micrognathia is a rare congenital condition that is difficult to treat and may result in recurrence. In a series of affected patients, we compared two new methods of treatment: transport distraction osteogenesis and Matthews Device arthroplasty. All patients had computed tomography scan documented bilateral TMJ bony ankylosis. Group I (transport distraction osteogenesis) underwent distraction advancement of the mandible (for micrognathia) followed by resection of the condyles, recontouring of the glenoid fossas with interposition temporoparietal-fascial flaps, and transport distraction osteogenesis of mandibular rami segments. Group II (Matthews Device arthroplasty) underwent all of the above procedures except for transport distraction osteogenesis. Instead, the Matthews Devices were anchored to the temporal bone and mandibular rami. Hinged arms allowed for motion at the reconstructed TMJ. In both groups, patients underwent extensive postoperative therapy. Preoperative, postoperative, and follow-up lateral cephalograms were obtained, and incisor opening distances were recorded. All patients but one had severe micrognathia (n = 9). For group I (transport distraction osteogenesis), mean age was 6.8 years. and mean advancement was 28.5 mm. For group II (Matthews Device arthroplasty) mean age was 8.2 years, and mean advancement was 23.5 mm. In group I (transport distraction osteogenesis), mean incisor opening was 1 mm preoperatively and 27.5 mm postoperatively; however, it relapsed to 14.3 mm by 12.5 months follow-up (48% relapse). Mean incisor opening in group II (Matthews Device arthroplasty) was 3.9 mm preoperatively and 33.4 mm postoperatively and remained at 30.6 mm after 11.1 months follow-up (8% relapse). One patient in group I (transport distraction osteogenesis) underwent surgical revision because of relapse. Our data showed that for congenital TMJ bony ankylosis both transport distraction osteogenesis and Matthews Device arthroplasty techniques were successful initially; however, the Matthews Device arthroplasty avoided long-term relapse.     

The influence of the closing and opening muscle groups of jaw condyle biomechanics after mandible bilateral sagittal split ramus osteotomy

ObjectiveTo investigate the influence of the closing and opening muscle groups of the jaw on mandibular stability after mandibular bilateral sagittal split ramus osteotomy (BSSRO).Materials and methodsTo establish finite element models of four conditions (the normal mandible, preoperative mandibular prognathism, postoperative (BSSRO) mandibular prognathism, and mandibular prognathism following virtual BSSRO), we imported Digital Imaging and Communications in Medicine (DICOM) data into three-dimensional reconstruction software. Finite element analysis software and statistical software were used for analysis of the condylar stress distribution as a function of condylar position during the actions of jaw closing and jaw opening muscle groups.ResultsThe stress distribution of the normal mandibular bilateral condyle was statistically different from the normal mandibular condyle, indicating that bilateral structures are asymmetrical. There was a significant difference in stress distributions with condyle position between healthy control patients and patients prior to mandibular prognathism surgery (P < 0.05). There was no significant difference in stress distributions between the normal mandible and the mandible following virtual surgery or real mandibular prognathism surgery. Additionally, there was no significant difference at 6 months after mandibular prognathism surgery (P > 0.05).ConclusionsBilateral structures of the normal mandible were asymmetrical. After mandibular bilateral sagittal split ramus osteotomy, variation of the force arms of closing and opening muscle groups of the jaw was one of the major factors influencing mandibular stability. Virtual surgery is a promising strategy for preoperative planning to improve surgical success and reduce complications.