Effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance

Abstract

Purpose:To verify the effect of sitting posture with and without soleground contact on chewing stability and masticatory performance. Methods: Thirty healthy subjects were evaluated. The Conformat was used to analyze the center of sitting pressure (COSP), and the threedimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained in a sitting position with and without sole-ground contact. The parameters of masticatory performance and movement were calculated as follows. For evaluating masticatory performance, the amount of glucose extraction (AGE) during chewing of a gummy jelly was measured. For evaluating masticatory movements, the movement of the mandibular incisal point was recorded using the Motion Visi-Trainer V1, and parameters of the stabilities of movement path and rhythm were calculated. Results: Head and trunk sway values and the displacement of COSP were significantly smaller with sole-ground contact than those without soleground contact. The masticatory movement path with sole-ground contact showed less variation in the opening distance and more stable movement path compared to those without sole-ground contact. The AGE was significantly greater with sole-ground contact than that without sole-ground contact. Conclusion:Sitting posture with and without sole-ground contact affects chewing stability and masticatory performance.Keywords: center of sitting pressure, chewing stability and masticatory performance, head and trunk postures, sitting posture, with and without sole-ground contact Materials and Methods Study population and ethicsIn total, 30 healthy male subjects with an average age of 25.3 years (range, 22-32 years) were recruited among the students and staff members of the Graduate School of Dental Medicine, Hokkaido University. The sample size was calculated using the software program G*Power 3.1.9.2 (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany). When the sample size was calculated by setting α = 0.05, β = 0.8, and effect size = 0.8, 26 participants were needed. All subjects met the following inclusion criteria:(1) healthy condition, (2) no history of head and neck or back problems, (3) no history of orthopedic or otolaryngologic problems affecting body balance, (4) no history of signs or symptoms of temporomandibular joint or orofacial pain, (5) absence of prosthesis (i.e., crowns, bridges, implants, or removable prosthetics) and Class I dental occlusion, and (6) no loose or broken teeth, fillings, or crowns that could be further damaged during the course of this study. This study was approved by the ethical committee of the Graduate School of Dental Medicine, Hokkaido University (approval number 2019-No. 2) and was conducted in accordance with the ethical principles of the Declaration of Helsinki. The study methodology was explained, and written consent was obtained from all participants prior to their inclusion in the study. Measurement posturesTwo postures were used for the measurement: a sitting posture without the soles of...