Temporomandibular joint ankylosis (TMJA) is one of the disorders that can impair the function of the masticatory system . TMJA usually occurs in the first and second decades of life. According to a study by Elgazzar, the prevalence of TMJA was higher in patients aged 11-20 years . Also, in a study conducted by Gaurav et al. on 44 patients with TMJA, it was reported that about two-thirds of the patient were under 15 years old . However, in our study, we reported that the most affected age group belonged to the age of 20-29 years with a frequency of 10 people (31/3%); we think this discrepancy is because, in our study, the age of the patients was recorded at the time of treatment and not at the onset of the disorder.
The prevalence of TMJA in men is often higher than in women. In our study, 71/9% of patients were male, and the ratio of male to female involvement was 23 to 9.
Many reasons can lead to TMJA. Various studies have identified trauma as the common cause of TMJA. For example, in a study by Roychoudhury in India, trauma was an etiological factor in 86% of cases . Also, in a study conducted by Zhi et al. In china, trauma was the cause of the TMJ ankylosis in 83.33% of patients . In our study, trauma was the cause of TMJA in 78/1% of patients, and in most cases, trauma was caused by motor-car accidents (n=13). Different criteria are used to classify the TMJ ankylosis (location, type of involved tissue, the extent of the fusion). In our study, we used the extent of the fusion. According to this system, a patient with a maximum mouth opening lower than 5 mm is considered complete ankylosis, and a maximum mouth opening of more than 5 mm is considered incomplete ankylosis. Based on this, out of 32 patients, 24 patients had complete temporomandibular joint ankylosis.
Untreated fractures of the zygomatic arch can cause extracapsular temporomandibular joint ankylosis. In our study of 25 patients with 33 involved joints with temporomandibular joint ankylosis due to the trauma, n=1 patients had an untreated zygomatic arch fracture without any condylar fracture. Among the other 24 patients with 32 involved joints, TMJA was caused by condylar fracture; in 30 condyles, the fracture pattern was intracapsular, and in 2 condyles, it was extracapsular. A study was performed by Long X et al. on the relationship between temporomandibular joint ankylosis and condylar fractures; the results showed that ankylosis is usually caused by intracapsular injuries . Also, According to a study conducted by Dongmei He et al. on the 40 involved joints, the condylar fracture pattern in 37 joints was intracapsular . Miyamoto et al. concluded from an animal study that intracapsular condylar fracture increased the risk of ankylosis of the TMJ . In our study, the leading chief complaint of patients was a restriction in mouth opening. In all of the studies performed on patients treated for TMJA, maximum mouth opening increased significantly after surgery. Westermark reported 12 patients with TMJ ankylosis treated based on this study; maximum mouth opening in patients with ankylotic joints improved from 3.8 mm before surgery to 30.2 mm after surgery . In our study, The mean of maximum mouth opening before surgery was 9/5 mm, which increased significantly to 40/02 mm after surgery. Therefore, to improve the quality of life of these patients, this disorder should be diagnosed and treated as soon as possible. The management of TMJA is very challenging . Different techniques for the management of TMJA have been devised in studies . Surgical interventions mainly include gap arthroplasty, interpositional arthroplasty, and hemi or total joint replacement [10, 22, 23]. In the present study, all patients were treated by gap arthroplasty with interpositional flap; condylectomy with coronoidectomy was performed in most cases.
Following surgery for treatment of TMJA, various complications such as re ankylosis, restriction in mouth opening the mouth, damage to the facial nerve, and malocclusion can occur, of which re ankylosis and mouth opening limitation are the most common [9, 24, 25].