Comparative Study of TMD in Young Population between USA and Japan

There are no previous studies comparing Temporomandibular Disorders (TMD) in children and young adults between Western and Eastern countries. Objectives: The purpose of this study was to assess chief complaints, diagnoses, treatments and outcome in young TMD patients and to compare them between USA and Japan. Methods: Sixty-four TMD patients (46 females, 18 males; 16.3 ± 2.5 years) at the University of California San Francisco Center for Orofacial Pain and 25 TMD patients (17 females, 8 males; 14.5 ± 5.1years) at the Nippon Dental University Hospital pediatric dental clinic were selected. All of the patients received a comprehensive examination including the RDC/TMD and assessed by using standardized examination and outcome forms (English or Japanese). An outcome form was consisted of 5 pain ratings (0-10 scale) in orofacial region and 7 daily living activity ratings (0-10 scale). The outcomes were analyzed by a change of pain ratings and activity ratings before and after treatment. Chi-square and Mann-Whitney's statistics were utilized for comparisons. Results: Gender ratio, ages, chief complaints and diagnoses were not significantly different between USA and Japan. Most common diagnosis of young TMD patients was disc disorder; USA (66%) and Japan (76%), and second common was myofascial pain; USA (66%) and Japan (56%). Percentages of various treatments were significantly different between two clinics (P<0.0001), but all of the treatments completed at both clinics were conservative. Medications tended to be used for TMD patients more in USA (57%) than in Japan (4%). However, percentage of patients who received better outcome was not significantly different between USA (78.3%) and Japan (70.6%). Conclusions: These results suggest that diagnoses of TMD in a young population are not different between these two countries, and even if treatment for TMD is different between them, conservative treatments for young TMD patients can result in a good outcome.