The reciprocal jaw-muscle reflexes elicited by anterior- and back-tooth-contacts-a perspective to explain the control of the masticatory muscles

Effects of occlusal conditions on masseter and temporalis muscle activity: An electromyographic evaluation

Introduction

Dental occlusion contributes to the development of temporomandibular disorder.

Objective

This case control study examined the influence of different occlusal conditions on the surface electromyography (sEMG) of the superficial part of the masseter muscle (MM) and anterior part of the temporalis muscle (TA) during clenching in the maximum intercuspal position (MIP).

Materials and methods

Twelve healthy subjects had their anterior, right posterior, or left posterior teeth added by composite resin to generate the bilateral posterior, unilateral left, or unilateral right posterior tooth losses, respectively. Muscle activity in the resting stage, MM's and TA's maximum voluntary clenching (MVC; µV) in MIP, each muscle activity's symmetry (%), and ipsilateral MM and TA synergy (%) were measured by sEMG. All parameters were analyzed by SPSS version 23.0, and the significance level was set at p < 0.05.

Results

The MM's and TA's sEMG activity at the resting stage significantly differed from those at the other occlusal conditions (p < 0.05). Both muscles' MVC were highest at the MIP during clenching but lowest during anterior clenching. During unilateral posterior clenching, such MVC was higher at the occluding than at the non-occluding sides. The TA's symmetry during clenching at the anterior and unilateral posterior teeth was lower than that at the MIP during clenching. No significant difference was seen in the ipsilateral MM and TA synergy.

Conclusion

Different occlusal conditions influenced the MM's and TA's sEMG activity. Each masticatory muscle responded differently to the same occlusal conditions.

Sustainable Solutions for Oral Health Monitoring: Biowaste-Derived Triboelectric Nanogenerator

Oral healthcare monitoring is a vital aspect of identifying and addressing oral dental problems including tooth decay, gum pain, and oral cancer. Day by day, healthcare facilities and regular checkups are becoming more costly and time-consuming. In this context, consumers are moving toward advanced technology, such as bite sensors, to obtain regular data about their occlusal chewing patterns and strength. The triboelectric nanogenerator (TENG) can potentially eliminate the need for a battery by simply converting abundant vibrations from nature or human motion into electrical energy. In this work, biomaterials are obtained from biowastes such as cellulose from wood waste, chitosan from crab shells, and gelatin from fish scales. All wastes are biodegradable, and our work aims at sustainability and waste hierarchy. The single electrode mode-based TENG was designed and fabricated using biodegradable poly(vinyl alcohol) (PVA)-biomaterial composites, rice paper as a substrate, and edible silver leaf as an electrode. The highest electrical output was obtained for PVA/chitosan 10 wt % composite-based TENG (PC10) of about 20 V, 200 nA, and 12 nC. The biomechanical energy harvesting was measured, and powering of LED was demonstrated using a PC10 TENG device. A biocompatible bite sensor based on the TENG was used to measure the biting force of a dummy teeth model to demonstrate its potential use in dental health applications. It indicates the promising future value of disposable oral medication devices without any invasive surgery or injection.

Comparison of Occlusal Parameters between Open Bite and Nonopen Bite Patients Using the T-Scan III System: A Pilot Study

Objective  To evaluate and compare the first tooth contact region, occlusion time, time to generate total force, and force distribution between open bite (OB) and non-OB (NOB) patients at the maximum intercuspation position using the T-Scan III system.

Materials and Methods  Sixteen patients were divided into the OB and NOB groups ( n  = 8 for each group). The T-Scan III system was used to evaluate the first tooth contact region, occlusion time, time to generate total force, and force distribution.

Statistical Analysis  The mean patient age, overjet, overbite, occlusion time, and time to generate total force were compared between the groups by independent samples t -test. Relative force distributions between groups and among regions were compared by the Mann–Whitney U- and Kruskal–Wallis H -tests, respectively. A probability value of less than 5% ( p  < 0.05) was considered significant.

Results  Differences in the first tooth contact region between groups were observed. The molar region was the first tooth contact region in the OB group, while first tooth contact was observed in all regions in the NOB group. Neither the occlusion time nor the time to generate total force was significantly different between the groups ( p  > 0.05). The highest force distributions were observed in the molar regions in both groups. Significant intragroup differences were found among all regions ( p  < 0.05), except between the anterior and premolar regions in the NOB group ( p  = 0.317). Intergroup differences in the force distributions in the anterior ( p  = 0.000), premolar ( p  = 0.038), and molar ( p  = 0.007) regions were significant.

Conclusion  Unlike in the NOB group, in which first tooth contact occurred in every region, in the OB group, first tooth contact occurred only in the molar region. Compared with those in the NOB group, the force distributions in the OB group were approximately 1.5 times higher in the molar region but were significantly lower in the anterior and premolar regions.

BDJ Open (2019-2020) and the advantages of open access publishing

BDJ Open is the open access sister journal to the British Dental Journal, and this paper aims to explore the various different articles that BDJ Open has published between 2019 and 2020, in order to highlight which areas authors felt were important to publish open access. Furthermore, this article will investigate the advantages of open access publishing to both authors and readers, as well as the scientific community in general, and will examine how open access publishing has allowed the BDJ Portfolio to publish a wide range of research, both in terms of topic and geography.

Examines papers published in BDJ Open between 2019 and 2020 to highlight which areas researchers felt were important to publish open access.

Discusses the advantages of open access publishing to authors, readers and the scientific community.

Explores how open access publishing has allowed the BDJ Portfolio to publish a far wider range of research both geographically and subject-wise.