Materials and methods

This study was carried out on 100 adult male patients who presented to the oral and maxillofacial department of a specialized dental teaching hospital in Cairo, Egypt. The patients ranged in age from 17 to 35 years. The mandibular fractures were secondary to road traffic accidents in all cases. Patients were included if the accident had occurred within the previous 10 days. Patients were excluded from the study if they had a previous history of TMJ disorders or joint surgery. Patients with systemic or local pathological conditions that might alter the normal shape, relationships, or structures of the TMJ were also excluded from this study. Furthermore, cases diagnosed with a high intracapsular fracture and those diagnosed with other facial injuries in addition to the mandibular fractures were excluded from the study.

The patients were divided into five groups based on the site of the mandibular fracture. Group 1 comprised patients who had unilateral condylar fractures. Group 2 patients had a unilateral condylar fracture and another mandibular fracture on the same side. Group 3 included patients who had a unilateral condylar fracture and a mandibular fracture on the opposite side. Group 4 patients had a mandibular fracture without a condylar fracture. Finally, group 5 patients had bilateral condylar fractures only.

TMJs were examined for swelling of the pre-auricular region, tenderness on palpation, deviation during opening, open bite, limitation of mouth opening and maximum mouth opening (MMO), movement of the condylar head, and abnormal sounds from the TMJs, such as clicking or crepitating sounds. The fracture sites and the TMJs were viewed through panoramic radiographs (reverse Towne’s view) and computed tomography if indicated. The presence and/or absence of displacement, post-traumatic malocclusion, and loss of posterior vertical height, as well as the surgical and post-surgical procedures performed to restore the occlusion and rehabilitate mandibular function were recorded.

MRI of the TMJ was performed in each case within 10 days from the date of injury. The same clinical, radiographic, and MRI examinations were performed at the end of treatment and 5 years later. All MRI studies were performed using a 1.5 T superconducting magnet (Magnetom H15 SP; Siemens, Erlangen, Germany). Both TMJs were imaged using a bilateral surface coil 20 cm in diameter within the surface coil holder. Items that could interfere with the magnetic resonance examination were checked. All patients underwent imaging in the sagittal plane, approximately 1.5 cm deep to the skin surface anterior to the tragus of the ear. Multiple sagittal slices with an image thickness of 2 mm were obtained. T1-weighted images were acquired with a spin echo technique (repetition time of 660 ms, echo delay time of 15 ms, and field of view of 200 mm). The imaging was repeated in the open mouth position, applying the same parameters, in patients who were able to sustain this position.

The surgical treatment of each mandibular fracture (body and angle) was open reduction and internal fixation using semi-rigid 2-mm titanium plates (titanium low profile osteosynthesis system; KLS Martin, Tuttlingen, Germany). Condylar fractures were managed conservatively, which consisted of 2 weeks of intermaxillary fixation (IMF), followed by a period of 2 weeks of IMF with light elastics to restore the occlusion and rehabilitate mandibular function.

The statistical analysis was performed using Microsoft Office 2013 (Excel) and IBM SPSS Statistics version 20.0 (IBM Corp., Armonk, NY, USA). The level of significance was set at P ≤ 0.05. The χ ² test was used to compare values between groups. The McNemar test was used for the comparison between early and late changes on the same TMJ sides within groups.

Results

Twenty patients who fulfilled the selection criteria were studied in each group. The patients ranged in age from 17 to 35 years.

MRI changes in both TMJs following the different types of mandibular fracture, at the acute stage and at the 5-year follow-up, are described in Table 1 .

In group 1 (unilateral condylar fractures), the MRI of the principal injured joint showed joint effusion and anterior disc displacement (ADD) without reduction in 10 cases. Two patients had ADD without reduction and without joint effusion, while eight patients had no changes. The other joint was not affected. Tenderness over the TMJ on the same side as the fracture was found in 10 patients. Four of them had deviation of the mandible to the same side as the fracture. Tenderness over the other TMJ side was noted in two patients.

After 5 years of follow-up, MRI examinations of the affected side showed 12 cases of ADD without reduction, two of ADD with reduction, and no changes in the other six joints. MRI of the TMJ of the opposite side showed ADD with reduction in seven cases. Clinically, tenderness over the joint was noted in eight patients. Six of them had deviation of the mandible towards the same side as the fracture. Tenderness over the other TMJ side was detected in four patients. Clicking of the TMJ on the same side as the fracture was noted in two patients and clicking over the TMJ on the other side was observed in five patients.

In group 2 (unilateral condylar fracture and another mandibular fracture on the same side), MRI investigation during the acute stage showed ADD without reduction of the injured joints in five cases, while joint structures were noted to be normal in the remaining 15 cases. The other joint was not affected in all cases. Tenderness over the same side as the fracture was noted in nine patients. Three of them had deviation of the mandible to the same side as the fracture. Tenderness over the other TMJ side was observed in five patients.

After 5 years of follow-up, MRI showed ADD without reduction of the TMJ on the same side as the fractures in two cases. MRI of the opposite joint showed ADD without reduction in two cases. Tenderness over the same side as the fracture was detected in 10 patients. Four of them had deviation of the mandible towards the same side as the fracture. Tenderness over the TMJ of the opposite side was observed in six patients. Clicking of the TMJ on the same side as the fracture was noted in four patients, while clicking of the TMJ on the opposite side was noted in seven patients.

In group 3 (unilateral condylar fracture and a mandibular fracture on the opposite side), MRI of the condylar fracture joint showed ADD without reduction in seven cases, joint effusions and ADD without reduction in four cases, and ADD with reduction in five cases; the remaining four cases did not show TMJ changes. MRI of the other joint showed five cases of ADD with reduction, while 15 joints were not affected. Tenderness over the TMJ on the condylar fracture side was noted in six patients. Two of them had deviation of the mandible towards the same side as the fracture. Tenderness over the other TMJ side was found in four patients.

After 5 years of follow-up, MRI of the affected joint showed ADD without reduction in 10 cases only. MRI of the opposite joint showed ADD without reduction in seven cases. Tenderness over the TMJ on the same side as the condylar fracture was detected in nine patients. Three of them had deviation of the mandible towards the same side as the fracture. Tenderness over the other TMJ was observed in six patients. Clicking of the TMJ on the same side as the condylar fracture was noted in three patients, while clicking of the TMJ on the opposite side was detected in five patients. Bilateral TMJ pain was reported in two patients. Bilateral click was noted in two patients who also had limited mouth opening.

In group 4 (mandibular fracture without a condylar fracture), MRI showed ADD with reduction of the TMJ joint on the same side as the fracture in three cases. MRI of the TMJ on the non-fractured side showed joint effusion in two cases. Tenderness over the TMJ on the same side as the mandibular fracture was observed in three patients. Tenderness over the other TMJ was observed in the other two cases. Mandibular deviation was not detected.

After 5 years of follow-up, MRI showed ADD with reduction on the same side as the fracture in two TMJs. ADD with reduction was noted in the TMJ of the opposite side in two cases. Tenderness was detected in the TMJ on the side of the mandibular fracture in six patients. One of them had deviation of the mandible towards the same side as the fracture. Tenderness over the other TMJ side was detected in four patients. Clicking of the TMJ on the same side as the fracture was noted in two patients, while clicking of the TMJ on the opposite side was detected in five cases. Bilateral TMJ pain was a major concern in three patients. Bilateral click was noted in one case.

In group 5 (bilateral condylar fractures only), ADD without reduction and with joint effusion in both sides was noted in 15 cases. ADD without reduction and without effusion in both sides was noted in five cases. Tenderness over the condylar fracture was detected in all cases.

After 5 years of follow-up, the MRI of both TMJs of the 20 patients showed ADD without reduction. Tenderness over the TMJs was recorded in eight patients. Clicking of the TMJ on one side was observed in five patients, while bilateral clicking of the TMJ was detected in seven patients. An anterior open bite was noted in three patients and limited jaw movement was observed in four cases.