Can Masticatory Electromyography be Normalised to Submaximal Bite Force?

Applications for oral research in microgravity - lessons learned from burning mouth syndrome and ageing studies

The negative consequences of microgravity for the human body are central aspects of space travel that raise health problems. Altered functions of the same systems and treatment options are common points of spaceflight physiology, age-related diseases, and oral medicine. This work emphasizes the convergence of knowledge between pathophysiological changes brought on by aging, physiological reactions to microgravity exposure, and non-pharmacological and non-invasive treatment methods that can be used in spaceflight. Sarcopenia, peripheral nerves alterations, neuromotor plaque in the masticatory muscles, lingual, labial, and buccal weakness, nociplastic pain in oral mucosal diseases, and microgravity, as well as soft tissue changes and pathologies related to chewing and swallowing, corticomotor neuroplasticity of tongue, and swallowing biomechanics, are of particular interest to us. Neurologic disease and other pathologies such as recovery from post-stroke dysphagia, nociplastic pain in glossodynia, sleep bruxism, and obstructive sleep apnea have been studied and, in some cases, successfully treated with non-invasive direct and transcranial magnetic stimulation (TMS) methods in recent decades. An interdisciplinary team from medical specialties, engineering, and biophysics propose an exploratory study based on the parallelism of ageing and space physiology, along with experiment scenarios considering TMS and non-invasive direct methods.

Impact of pivoting bite tip on bite force measurement tests

OBJECTIVE

Present a gnathodynamometer design that increases patient comfort, precision, and/or ease for the operator during bite force tests.

MATERIALS AND METHODS

A bite tip capable of pivoting 180° was tested on senior dental students in a double-blind trial. The tests were performed in teeth 11 and 16 with the bite tip on the long axis of the clamp and at an angle of 90° to the clamp. The sample was composed of 24 students, 13 males and 11 females, randomly divided into two groups: the operator group (OP), which was composed of 12 students, 7 males and 5 females, and the test group (TI), which was composed of 12 students, 6 males and 6 females. The operator and participants were asked to evaluate comfort and precision/ease in positioning the bite tip by attributing scores from 0 (total discomfort) to 10 (total comfort) during the test.

RESULTS

No difference was noted in tooth 11 (P > 0.05). In tooth 16, there was a statistically significant improvement (P < 0.01) for the participants tested and the operator using the pivoting bite tip.

CONCLUSIONS

The pivoting bite tip showed no difference in the comfort of the participants and operator precision when testing incisors; however, the tip showed a difference for both conditions in the molar region. The gnathodynamometer geometry showed good results in participant comfort and operator precision when used in bite force tests of the incisors and molars. Further investigations are needed to confirm whether these improvements influence the mean value and maximum bite force measurement.

CLINICAL RELEVANCE

Bite force measurement is a method for obtaining important data to check the functional conditions of the stomatognathic system. With the aging of the world population, it has become important to check the quality of life during aging. The pivoting bite tip improves the comfort and precision of bite tests for the participants tested and for the operator, respectively.

Evaluation of 1-Piece Versus 3-Piece Framework Designs for the Edentulous Mandible with Fixed Implant-Supported Prostheses: A Clinical, Occlusal and Biomechanical Study

PURPOSE

This study aims to evaluate the clinical, occlusal and biomechanical performance of 1-piece and 3-piece designs for implant-supported fixed dentures in the edentulous mandible.

MATERIALS AND METHODS

A total of 65 patients with edentulous mandibles who underwent fixed implant-supported restorations were recruited and subsequently assigned to 1 of 2 groups based on the framework design (1-piece or 3-piece). The participants underwent clinical and occlusal examination using a periodontal probe, T-Scan III system, and electromyography 12 months after prosthesis delivery. Two mandibular finite element models were created to evaluate stress values and their distribution during function.

RESULTS

Ninety-five point four percent (n = 62) of participants in the follow-up period underwent clinical and occlusal examination after prosthesis delivery. Clinical examination revealed a trend towards increased inflammation around the implants in the 1-piece prostheses. Occlusal parameters indicated that the 1-piece design was superior for the masticatory system than the 3-piece design. Biomechanical analysis revealed the highest stress values in the posterior region of the 3-piece design.

CONCLUSIONS

On the basis of ease of ensuring oral hygiene, when compared to the 3-piece design, the 1-piece framework design might be the superior therapy for restoring an edentulous mandible, based on occlusal and biomechanical outcomes.

Myorelaxant Effect of Transdermal Cannabidiol Application in Patients with TMD: A Randomized, Double-Blind Trial

(1) Background: The healing properties of cannabidiol (CBD) have been known for centuries. In this study, we aimed to evaluate the efficiency of the myorelaxant effect of CBD after the transdermal application in patients with myofascial pain. (2) Methods: The Polish version of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD Ia and Ib) was used. A total of 60 patients were enrolled in the study and were randomly divided into two groups: Group1 and Group2. The average age in Group1 was 23.2 years (SD) = 1.6 years) and in Group2, it was 22.6 years (SD = 1.86). This was a parallel and double-blind trial. Group1 received CBD formulation, whereas Group2 received placebo formulation for topical use. The masseter muscle activity was measured on days 0 and 14, with surface electromyography (sEMG) (Neurobit Optima 4, Neurobit System, Gdynia, Poland). Pain intensity in VAS (Visual Analogue Scale) was measured on days 0 and 14. (3) Results: in Group1, the sEMG masseter activity significantly decreased (11% in the right and 12.6% in the left masseter muscles). In Group2, the sEMG masseter activity was recorded as 0.23% in the right and 3.3% in the left masseter muscles. Pain intensity in VAS scale was significantly decreased in Group1: 70.2% compared to Group2: 9.81% reduction. Patients were asked to apply formulation twice a day for a period of 14 days. (4) Conclusion: The application of CBD formulation over masseter muscle reduced the activity of masseter muscles and improved the condition of masticatory muscles in patients with myofascial pain.

Bite force and dental implant treatment: a short review

Dental implants are placed endosseously, and the bone is the ultimate bearer of the occlusal load. Patients are not uniform in the maximum bite force they can generate. The occlusal biting load in the posterior jaw is usually about three times of that found in the anterior. It is possible for supporting implants to be overloaded by the patients’ biting force, resulting in bone loss and failure of the fixture. Bite force measurement may be an important parameter when planning dental implant treatment. Some patients can generate extreme biting loads that may cause a luxation of the fixture and subsequent loss of osseointegration. A patient with low biting force may be able to have a successful long-term outcome even with poor anatomical bone qualities. Patients with a high bite force capability may have an increased risk for late component fracture or implant failure. There is no correlation of any bite force value that would indicate any overload of a given implant in a given osseous site. Nonetheless, after bite force measurement, a qualitative judgement may be made by the clinician for the selection of an implant diameter and length and prosthetic design.

Finite element analysis on tooth and periodontal stress under simulated occlusal loads

The tooth stress elicited by occluding contact represents critical biomechanical information about dental health during chewing. Effects of occlusal contact on tooth stress remain obscure. In this study, a mandibular first molar finite element model was built from CT images. The effects of area size, location and direction of occlusal loading on both tooth and periodontal stresses were analysed. Results showed tooth and periodontal stress had drastically different patterns. Tooth stress value was much higher than periodontal stress value under the same task. Tooth stress concentration area and its value decreased from outside to inside. The Maximum Tooth Stress (MTS) always occurred at the loading site and a larger loading area elicited a smaller MTS value. The variation of MTS was larger when the fossa bottoms were inclined loaded than when the cusp tips were inclined loaded, larger when lingually loaded than when buccally loaded and larger when mesially loaded than when distally loaded. Distal loadings generally induced smaller Maximum Periodontal Stress (MPS) variations than the mesial loadings. These findings indicated exposure of the rational site(s) to occlusal contact should be helpful to achieve proper tooth and periodontal stress, thus to diminish loading associated structure problems.

Electromyography analysis of natural mastication behavior using varying mouthful quantities of two types of gels

The objectives of this study were to examine the effects of mouthful quantities and mechanical properties of gels on natural mastication behaviors using electromyography (EMG). Two types of hydrocolloid gels (A and K) with similar fracture loads but different moduli and fracture strains were served to eleven normal women in 3-, 6-, 12-, and 24-g masses in a randomized order. EMG activities from both masseter muscles were recorded during natural mastication. Because of the similar fracture loads, the numbers of chews, total muscle activities, and entire oral processing times were similar for similar masses of both gel types. Prior to the first swallow, the more elastic K gel with a higher fracture strain required higher muscle activities than the brittle A gel, which had higher modulus. Majority of subjects had preferred sides of chewing, but all subjects with or without preferred sides used both masseters during the consumption of gels. Similar effects of masses and types of gels were observed in EMG activities of both sides of masseters. Contributions of the dominant side of chewing were diminished with increasing masses of gels, and the mass dependency on ratio of the dominant side was more pronounced with K gel. More repetitions of smaller masses required greater muscle activities and longer periods for the consumption of 24-g gel portions. Reduction in the masses with an increased number of repetitions necessitated slower eating and more mastication to consume the gel portions. These observations suggest that chewing using both sides is more effective and unconsciously reduces mastication times during the consumption of gels.