# Gender Differences in Clinical Characteristics of Korean Temporomandibular Disorder Patients
## 4 Discussion  
It is well known that women hold the majority of patients seek for treatment of TMD. Numerous studies reported a female predominance of prevalence of TMD, but there are few studies using diagnostic tools such as RDC/TMD and SCL-90-R for multi-aspect analysis on large sample in Korea. Furthermore, a recent population-based study revealed that gender differences in the prevalence of orofacial pain including TMD are increasing over time [26]. Therefore, it needs to analyze the recent data on gender differences of Korean TMD patients and associations with biological and psychosocial factors. Our study investigated the gender effect on the clinical signs and symptoms of TMD patients, and analyzed its differences based on RDC/TMD and psychosocial characteristics. Our data showed that the prevalence of TMD in women was about 3 times more than in men (women, 75.2%; men, 24.8%) and mean age was 35.9 \(\pm\) 15.7 years and 29.7 \(\pm\) 14.8 years, respectively. The female predominance in TMD shown in the present study is consistent with previous studies. Numerous studies reported that women visited clinics for treatment of TMD about 3-9 times more than men, and women had TMJ pain from 1.5 to 2 times in women than men in the community [6; 26]. Meanwhile, the results showed a large standard deviation compared to mean value relatively in the number of systemic comorbidities and pain duration. It might be caused by variation of patients who had chronic pain and various systemic diseases. The result showed that prevalence of TMJ disc displacement without reduction was higher in women than men. This is consistent with a previous study with using MR image, reporting that women had a higher prevalence of TMJ disc displacement without reduction [27]. Meanwhile, the female predominance in TMJ osteoarthritis (OA) shown in the present study is consistent with previous studies [28; 29]. The reason for this result is unclear, but may be affected by differences of sex hormones, pain perception, response to stress, and psychological factors. However, there are other epidemiologic studies showing opposite results in the prevalence of TMJ OA. Some investigators have indicated that the actual changes in joint morphology do not have any statistically significant gender differences [30; 31], and some even suggested a higher incidence of OA in men [32; 33]. These differences could be caused by the differences of diagnostic methods and the complexity of the disease. In this study, women showed higher prevalence of headache and subjective insomnia than men. Female predominance of headache is consistent with the previous global survey \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Pain Intensity**} & \multicolumn{2}{c}{**Number of Positive Muscle**} & \multicolumn{2}{c}{**Maximum Mouth Opening**} \\ \cline{2-7}  & \begin{tabular}{c} **Standardized** \\ **Coefficient (\(\beta\))** \\ \end{tabular} & \(p\)**-Value** & \begin{tabular}{c} **Standardized** \\ **Coefficient (\(\beta\))** \\ \end{tabular} & \(p\)**-Value** & \begin{tabular}{c} **Standardized** \\ **Coefficient (\(\beta\))** \\ \end{tabular} & \(p\)**-Value** \\ \hline Age & 0.048 & 0.148 & 0.074 & 0.024 * & \(-\)0.097 & 0.003 * \\ \hline \begin{tabular}{c} Gender \\ (Men = 1, \\ Women = 2) \\ \end{tabular} & 0.050 & 0.107 & 0.103 & 0.001 * & \(-\)0.208 & \textless{}0.001 * \\ \hline \begin{tabular}{c} Asymmetry of \\ occlusal \\ contacts \\ \end{tabular} & 0.034 & 0.266 & 0.016 & 0.590 & 0.023 & 0.454 \\ \hline \
\begin{tabular}{c} Number of \\ systemic \\ comorbidities \\ \end{tabular} & 0.071 & 0.030 * & 0.056 & 0.083 & \(-\)0.025 & 0.434 \\ \hline
\begin{tabular}{c} Adjusted \(R^{2}\) \\ values \\ \end{tabular} & 0.011 * & 0.022 * & 0.058 \\ \hline \hline \end{tabular} Results were obtained from multivariate linear regression analysis. * Significant difference, \(p\) \(<\) 0.05.  
\end{table}