## 4 Discussion  
This was a cohort study that attempted to ascertain the incidence of TMD at two different time points as compared with the baseline: during orthodontic treatment and one year after orthodontic treatment. Results showed that patients developed a low and not statistically significant increase in disc displacement, and there was a reduction in myofascali pain as compared with the baseline. There is not much evidence in the literature linking the development of disc displacement with orthodontic treatment. Literature reviews have shown that all forms of abnormal occlusion, including exaggerated Class II or Class III occlusions, edge-to-edge bite, or increased or reduced overjet and overbite, could increase the risk of developing disc displacement [24]. It is possible that, during the course of orthodontic treatment, the abnormal occlusion that develops before the bite is settled could bring on forward movement of the articular disc. In most cases, this appears to be temporary, and the clicking resolves on its own. However, in some cases, it could persist. In our study, all cases of disc displacement were merely associated with asymptomatic clicking, and we did not encounter cases that progressed to painful clicking or non-reducing displacements one year after the end of orthodontic treatment. Myofascali pain, although considered under TMD diagnoses, is a different entity. Several patients suffer from mild myofascali pain without even being aware of their condition. In the current study, on clinical examination, we found that more than half of the patients were already experiencing muscle tenderness. In a prospective case control study, [PERSON] et al. [25] assessed the effect of fixed orthodontic treatment on myofascali pain. They found that orthodontic treatment helped to improve the signs and symptoms of myofascali pain, although complete resolution did not occur. In the current study, we also found that there was a slight decrease in the incidence of muscle tenderness as compared with the baseline. In the current study, to assess myofascali pain, we used the modified pericardial muscle tenderness score described by [PERSON] et al. [17]. This score was originally developed for use with tension headaches. However, the two conditions are not unrelated, and this technique would be equally effective in detecting myofascali pain secondary to TMD [18]. The MTS and CTS scores evaluated two groups of muscles: the masticatory muscles and the cervical muscles. Cervical muscle tenderness is an important component of TMD. [PERSON] et al. [26] showed that cervical muscle tenderness was a prominent feature in patients with myogenous TMD, but only [PERSON] et al. [25] have evaluated pain in the cervical muscles during orthodontic treatment, reporting an improvement in myofascali pain after orthodontic treatment. In the current study, when only cervical tenderness was taken into account, it was found that the tenderness score actually decreased when compared with the baseline one year after orthodontic treatment. This parameter, therefore, is one that deserves more consideration in future studies. Several studies have tried to establish risk factors for developing TMD following orthodontic treatment [11; 12; 13]. Age has been demonstrated as a risk factor for development of TMD in previous studies. In a longitudinal study, [PERSON] et al. [27] found that young adults and adolescents, especially between the ages of 19 and 20, demonstrated a higher risk of persistent TMD following orthodontic treatment. In the current study, we found that a one unit increase in age increased the odds of developing TMD by 50%. However, these results were not statistically significant. Previous studies have highlighted that the female gender is more susceptible to the development of TMD following orthodontic treatment. This study showed that women had almost double the odds of developing TMD compared with men. The study by [PERSON] et al. [27] demonstrated slightly higher odds in a three-year follow-up period (OR = 2.45).