Purpose: The aim of this study was to compare changes of bite force, occlusal contact area, and dynamic functional occlusion analysis after occlusal stabilization splint therapy during sleep for one month in a patient with bruxism. Materials and Methods: From October 2021 to July 2022, sleep bruxism of 30 patients who visited the Department of Oral Medicine at Yonsei University College of Dentistry Hospital were recruited. The participants were divided into two groups: using an occlusal stabilization splint during sleep (treatment; n = 15) and not using an occlusal stabilization splint (control; n = 15). Before using the occlusal stabilization splint and one month after, bite force, occlusal contact area and dynamic functional occlusion analysis (ratio of left/right bite forces, average bite forces, maximum bite forces, and maximum contact areas during lateral and anterior and posterior mandibular movements) were performed. Results: There was no difference in bite force and occlusal contact area between the treatment group using the occlusal stabilization splint and the control group not using the occlusal stabilization splint during sleep for one month. However, there were significant differences in the average bite force and maximum bite force in the lateral and anterior and posterior mandibular movements and the maximum contact areas in the anterior and posterior mandibular movements. Conclusion The occlusal stabilization splint is helpful for sleep bruxism patients who lateral and anterior and posterior mandibular movements. In addition, further studies are needed a double-blind study with a large population.