Effects of increasing the jaw opening on the maximum bite force and electromyographic activities of jaw muscles

Abstract

Background/purpose: Increased occlusal jaw opening may lead to some changes in the bite force and electromyographic (EMG) activities of the jaw muscles. This in situ study was conducted to determine the immediate influence of three different occlusal vertical dimensions on the maximum bite force and EMG activities of the masseter and anterior temporalis muscles. Materials and methods: Five healthy subjects participated in the study. Two maxillary occlusal splints of 2 and 4 mm thickness were fabricated, and their use created, respectively, 8 and 10 mm of intermolar distances in the first molar region with a strain-gauge-mounted metal arch. EMG activities of the muscles and the maximum bite force were simultaneously recorded using an EMG device and two miniature strain-gauge transducers. Recordings were made in the first molar region without a splint, but with two splints to produce 6, 8, and 10 mm of intermolar distances. Results: EMG activities of both muscles decreased with increased jaw opening; however, the differences were not statistically significant. The highest maximum bite force was found at a 6-mm intermolar distance, which significantly differed from those at 8-and 10-mm intermolar distances (P < 0.05). The most efficient bite force was exerted with 6 mm of intermolar distance. The least EMG activity of both muscles was found with 10 mm of intermolar distance. Conclusion: An increase in the vertical thickness of the splint to 10 mm may provide an immediate effect of reducing masseter and anterior temporalis muscle hyperactivity.

Immediate effects of temporary bite-raising with light-cured orthodontic band cement on the electromyographic response of masticatory muscles

“…Further investigation including bite force measurements may assist in defining the cause of the reduced EMG activity during MVC after bite-raising with this method. The decreased EMG activity after bite-opening was greater for the superficial masseter compared to the anterior temporalis, which is consistent with the study of Koc, et al 11 (2012). This may result from the different muscle locations and orientations, resulting in these muscles being physically affected by changes in jaw position in a different manner.…”

“…The cause for this could be the opening distance chosen for this study, set at 2.5–3 mm, which is close to the physiological rest position and is usually adequate for treating orthodontic patients. However, several studies found that increasing the occlusal vertical dimension by ≥3 mm by other means affects the EMG activity of the superficial masseter and anterior temporalis muscles 4 , 11 . Therefore, the EMG response to bite-raising by this method at greater opening distances should be further investigated.…”

“…Several studies indicate that increased occlusal jaw opening may lead to changes on the electromyographic (EMG) activity of the jaw muscles and there are several studies on the consequence of bite-raising by other means on the EMG activity 4 , 11 . However, we do not know of any published studies on the effects of opening the bite by adding light-cured orthodontic band cement on the occlusal surfaces of the posterior teeth, on jaw muscle activity.…”

Evaluation of the effect of two different occlusal splints on maximum occlusal force in patients with sleep bruxism: a pilot study

“…In the present study, occlusal force of participants who used stabilization splint showed no statistically significant differences after the splint treatment. According to the results of our previous study, the mean maximum occlusal force of healthy participants was 30.16 kg30 and in the present study, the occlusal force value of participants recorded before and after the use of stabilization splint was close to the occlusal force of the healthy participants. It was considered that the lack of difference might be related to the severity of the bruxism and small number of the participated subjects.…”

“…3 ). 30 Two transducers were placed bilaterally on a flat metal arch. The metal surfaces of the arch were covered with plaster (Betasan, Kocaeli, Turkey).…”