Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 20 0 2023 05 07 1 9 EN Farzaneh Aghahoseini Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Iraj Mirzaii-Dizgah Department of Physiology, School of Medicine, Aja University of Medical Sciences, Tehran, Iran Shiva Shirazian Department of Oral Medicine, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Maryam Javaheri-Mahd Department of Oral Medicine, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2021 09 19 2022 08 01 Objectives: Temporomandibular disorders (TMDs) include a series of signs and symptoms in the temporomandibular joints (TMJ) and muscles of mastication, which are associated with or caused by parafunctional habits. Many of these patients also suffer from lumbar pains. This study aimed to evaluate the effectiveness of treating parafunctional habits in alleviating symptoms of TMD and lower back pain. Materials and Methods: This phase II clinical trial was conducted on 136 patients suffering from TMDs and lumbar pain, who consented to participate in this study. They were provided with instructions on how to discontinue their parafunctional habits including clenching and bruxism. The Helkimo and Rolland Morris questionnaires were used to assess TMD and lower back pain, respectively. Data were statistically analyzed using paired Student's t-test, Wilcoxon, Mann-Whitney, and Spearman correlation tests, with the significance level set at P<0.05. Results: The mean severity score of TMD significantly decreased after the intervention. Following treatment of TMD, the mean severity score of lumbar pain decreased from 8 to 2 (P=0.0001). Conclusion: Based on our findings, it appears that the elimination of parafunctional habits improves TMD and lumbar pain. https://fid.tums.ac.ir/index.php/fid/article/view/4200 https://fid.tums.ac.ir/index.php/fid/article/download/4200/2019