Tehran University of Medical Sciences Journal of Craniomaxillofacial Research 2345-5489 7 3 2020 12 26 145 151 EN Majid Sahebi Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Mohammadreza Hajimahmoudi Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Faezeh Atri Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. 2020 10 24 2020 11 30 Introduction: The aim of this study was to compare the efficiency of soft and hard splints in treating patients with clenching. Materials and Methods: In this clinical study, 26 patients with clenching disorder randomly divided to two equal group of treatment: hard and soft splint. The amount of masticatory muscle pain and maximum mouth opening were measured at the delivery time and 3, 6, 9, and 12 weeks later by a blind examiner. Data were analyzed by independent T and repeated measure ANOVA tests with significance level of p=0.05. Results: Hard and soft splints were resulted in significant reduction of masticatory muscle pain (hard: P<0.001, Soft: p<0.001) and increase in maximum opening (hard P<0.001, Soft p<0.003), but there was no significant difference between them in pain relieving (P=0.848) and maximum opening (P=0.622). Conclusion: This study showed that efficacy of hard and soft splints in treating patients with clenching is same. Keywords: Masticatory muscle; Maximum mouth opening; Occlusal splint; Pain. https://jcr.tums.ac.ir/index.php/jcr/article/view/350 https://jcr.tums.ac.ir/index.php/jcr/article/download/350/302