The association of self-reported awake bruxism with anxiety, depression, pain threshold at pressure, pain vigilance, and quality of life in patients undergoing orthodontic treatment

Abstract This study aimed to evaluate whether the presence of awake bruxism was associated with temporomandibular dysfunction symptoms, pain threshold at pressure, pain vigilance, oral health-related quality of life (OHRQoL), and anxiety and depression symptoms in patients undergoing orthodontic treatment. Methodology This observational study followed patients who had started receiving orthodontic treatment for six months. The following variables were measured three times (at baseline, one month, and six months): pressure pain threshold (PPT) in the right and left masseter, anterior temporalis, and temporomandibular joint (TMJ), and right forearm; pain vigilance and awareness questionnaire; and shortened form of the oral health impact profile (OHIP-14). Anxiety and depression symptoms were measured using the Beck anxiety inventory and the Beck depression inventory, respectively. The patients were divided into two main groups according to the presence (n=56) and absence (n=58) of possible awake bruxism. The multi-way analysis of variance (ANOVA) was applied on the date (p=0.050). Results TMJ and/or muscle pain were not observed in both groups. Time, sex, age group, and awake bruxism did not affect the PPT in the masticatory muscles and pain vigilance (p>0.050). However, the primary effect of awake bruxism was observed when anxiety (ANOVA: F=8.61, p=0.004) and depression (ANOVA: F=6.48, p=0.012) levels were higher and the OHRQoL was lower (ANOVA: F=8.61, p=0.004). Conclusion The patients with self-reported awake bruxism undergoing an orthodontic treatment did not develop TMJ/masticatory muscle pain. The self-reported awake bruxism is associated with higher anxiety and depression levels and a poorer OHRQoL in patients during the orthodontic treatment.


Introduction
Bruxism is frequently implied as a source of microtrauma in the temporomandibular joints (TMJs) and in the mastication muscles. However, the evolution of new definitions and diagnostic criteria for bruxism has great repercussions for the possible relationship between bruxism and craniofacial pain. 1 An international consensus recently defined bruxism as a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible, occurring within two distinct circadian manifestations: sleep and awake bruxism. 1 Such specifications of the different motor activities and physiological brain states featuring the bruxism manifestations highlight the need to consider their possible different causes and clinical consequences.
Awake bruxism is a masticatory muscle activity during wakefulness that is characterized by repetitive or sustained tooth contact and/or by bracing or thrusting of the mandible, and is not a movement disorder in otherwise healthy individuals. 1 Furthermore, the updated international consensus proposed a bruxism grading system to determine whether a certain bruxism assessment method actually offers a credible outcome. In addition, methods often used in the classification system for the bruxism diagnosis, such as self-report and clinical inspection, have been indicated as some of the only best leads to diagnose probable sleep or awake bruxism, and instrumental approaches are required for definitive bruxism assessments. 1,2 Until now, the possible relationship between bruxism and symptoms of temporomandibular disorders is still controversial in the literature due to the complexity of etiology and diagnostic of both disorders. [3][4][5] The hypothesis often discussed is the possible positive relationship between either awake or sleep bruxism and craniofacial pain is still a commonly held view in the clinical practice [3][4][5] , and sometimes even presented as a real and simple cause/effect relationship. In line with the perspective that painrelated temporomandibular disorders (TMD) must be envisaged within a biopsychosocial model of illness, and efforts to understand painful temporomandibular disorders along with other chronic pain conditions in a biopsychosocial context have been made. [5][6][7][8] This implies that the association between bruxism and painful temporomandibular disorders has become much more complex. 5 Orthodontists should be aware of the presence of general and awake bruxism in particular and their possible implications during an orthodontic treatment, such as the excessive use of the jaw and possible association with dental structure (e.g., dental wear and restoration failures), TMJ, and masticatory muscle damage. 9 Therefore, this study evaluates whether the presence of awake bruxism was associated with the occurrence of temporomandibular dysfunction symptoms, pain threshold at pressure, pain vigilance, oral health-related quality of life (OHRQoL), and anxiety and depression symptoms in patients undergoing orthodontic treatment. This study hypothesized a priori that patients with awake bruxism would present differences in deep pain sensitivity, pain vigilance, anxiety and depression symptoms, and OHRQoL, when compared with those without awake bruxism. The minimum desired sample size for this study was calculated using an odds ratio (OR) of 2.0; the test power was 70.0% (β= .10), and the standard error was 5% (α= .05).

Methodology
This observational study followed patients who had started orthodontic treatment with fixed appliance for six months. The patients receiving treatment using removable appliances were not included in the sample.
Initially, 162 patients were assessed for eligibility in several orthodontic specialization courses.
The inclusion criteria were the following: a) The association of self-reported awake bruxism with anxiety, depression, pain threshold at pressure, pain vigilance, and quality of life in patients undergoing orthodontic treatment J Appl Oral Sci.  or clenching of the teeth, which were adapted from the Oral Behavior Checklist (OBC); 16 nonetheless, this study has not applied the full questionnaire. The patients' group with awake bruxism was composed according to the answers regularly, often, or always.
The patients' group without awake bruxism was composed according to the following answers: "never", "sometimes".
For the age control, the sample was also divided into two groups according to the guidelines of the World Health Organization (WHO) for age groups: 17 adolescents (aged 10 to 19 years inclusive) and adults (older than 19 years of age).

Results
One hundred and fourteen healthy participants fulfilled the eligibility criteria and were enrolled in this study. The mean age (SD) of the sample was 24.7 (11.1) and 52% of them were women. In addition, 49% reported awake bruxism, where the mean age (SD) was 27.3 (12.5) and 64% of them were women.
The remainder 51% did not report awake bruxism, their mean age (SD) was 22.2 (9.1) and 41% of them There were no main effects of time, sex and age group, or awake bruxism on the pain vigilance (p>0.050). Also, there were no main effects of time, sex, and age group on the anxiety and depression symptoms. However, there was a main effect of awake bruxism where its presence was related with higher anxiety (ANOVA: F=8.61, p=0.004) and depression