A study of teeth grinding and TMJ syndrome among students of Oral and Maxillofacial of MNUMS in relation to chronotype

Abstract

Background: An excessive grinding of the teeth and clenching of the jaw are the main characteristics of condition known as bruxism. Sleep bruxism (SB) describes excessive grinding or clenching during sleep, while awake bruxism (AB) describes involuntary grinding or clenching during the day time. Bruxism can cause temporomandibular disorders (TMJ Syndrome), implant loss and tooth fracture. Although the cause of bruxism is not too clear, it is often due to the individuals stress level, lifestyle habits, personality type and certain characteristics such as chronotype. Chronotype refers to individuals’ natural inclination to sleep at certain time. In the past couple of years, increasing number of studies have been done around these different chronotype and its relation to one’s health and performance profiles. Individual can be divided into three main chronotypes; morningness, eveningness, and intermediate, based on their wakefulness and rest in relation to the time of the day. Moreover, these different types of chronotype have an effect on ones ademic performance, stress, stress related conditions, migraine, and other illnesses. Our study goal is to investigate to see if individuals being certain chronotypes has any correlation on them having bruxism and temporomandibular disorder symptoms(TMDs). Aim: The study aimed to investigate the impact of chronotypes on sleep bruxism (SB), awake bruxism (AB) and temporomandibular disorder symptoms (TMDs) among students from Mongolian National University of Medical Science (MNUMS) – School of Dentistry. Materials and Methods: 284 students from Mongolian National University of Medical Science (MNUMS) – School of Dentistry completed the questionary using analytical questionary model following Ethical committee approval was obtained by protocol 2022/3-06. Participation was on a voluntary basis, and all participants signed a consent form before the study onset. The morningness-eveningness questionnaire (MEQ) was used to analyze the chronotype profile and the Lobbezoo questionnaire was used to determine the bruxism among participants. The chi-square test, Mann-Whitney test, and t-test analyses were performed to evaluate the factors associated with sleep bruxism (SB), awake bruxism (AB), and temporomandibular disorder (TMD). Results: Among participants, 232 (81.7%) were women, and 52 (18.3%) were men, and average age was 21.16. Results showed that the association between sleep bruxism (SB) and chronotypes: morningness, eveningness, and intermediate were insignificant (p=0.427). However, association between awake bruxism (AB) and chronotypes were significant (p=0.028). There was no association found between chronotype and TMDs(p=0.091). In comparison to different chronotypes among people with awake bruxism, morningness profile is less than intermediate and eveningness profile (p=0.025). Also, TMDs are higher in individuals with eveningness profile than morningness profile (p=0.035). When students MEQ score lower indicating more likely to be eveningness profile they also tend to have higher chance of experiencing awake bruxism (p=0.009), TMDs (p=0.011). People with TMDs more likely to experience face head neck pain (p=0.016). When students have asked if they have either face head neck pain 128 (45%) were answered ‘yes’ and 109(38.3%) gets enough sleep, 76 (26.7%) experience nightmare. Moreover, people with morningness profile had higher number of insufficient sleep (р=0.029) Conclusions: 1. Among participants, 109(38.3%) has awake bruxism, 105(36.9%) has sleep bruxism and number of awake bruxism was fewer among people with morningness profile (р=0.028). 2. 162(57%) of the students reported to have TMDs, and there were more students with eveningness profile (р=0.035). 3. 44(15.5%) of participant were morningness profile, 206(72.5%) were intermediate, 34(12%) were eveningness profile. There was a correlation between lower MEQ score and higher tendencies to have awake bruxism (р=0.009) and TMDs (р=0.011).