Association of sleep quality and psychological aspects with reports of bruxism and TMD in Brazilian dentists during the COVID-19 pandemic

Abstract Dentists are exposed to contamination by SARS-CoV-2 due to dental interventions, leading to a state of alert and potential risk of negative impact in mental health and sleep quality, associated with Temporomandibular Disorder (TMD) and bruxism. Objective: to evaluate the psychosocial status, sleep quality, symptoms of TMD, and bruxism in Brazilian dentists (DSs) during the COVID-19 pandemic. Methodology: The sample (n=641 DSs) was divided into three groups (quarantined DSs; DSs in outpatient care; and frontline professionals), which answered an electronic form containing the TMD Pain Screening Questionnaire (Diagnostic Criteria for Temporomandibular Disorders – DC/TMD), the Pittsburgh Sleep Quality Index (PSQI), the Depression, Anxiety and Stress Scale (DASS-21), and the sleep and awake bruxism questionnaire. ANOVA test and Mann Whitney post-test were used, with Bonferroni adjustment (p<0.016) and a 95% confidence level. Results: Probable TMD was found in 24.3% (n=156) of the participants, while possible sleep and awake bruxism were diagnosed in 58% (n=372) and 53.8% (n=345) of them, respectively. Among all variables evaluated, only symptoms of depression were significantly greater in the quarantined DSs group when compared to those who were working at the clinical care (p=0.002). Working DSs were significantly less likely (OR=0.630, p=0.001) to have depressive symptoms. Those who were not worried or less worried about the pandemic were less likely to experience stress (OR=0.360), anxiety (OR=0.255), and poor sleep quality (OR=0.256). Sleep had a strong positive and moderate correlation with psychological factors on frontline workers and DSs in outpatient care, respectively. Conclusion: The results suggest confinement may have a more negative impact on the life of DSs than the act of being actively working. The concern about Covid-19 and poor sleep quality was significantly prevalent and may negatively affect the quality of life of DSs. Thus, further research on the topic is needed.


Introduction
Unpredictable or incomprehensible life situations, as the current pandemic caused by the Coronavirus Disease 2019 , are important sources of stress. 1 The causative agent of the disease is the new Coronavirus related to the Severe Acute Respiratory Syndrome (SARS-CoV-2). 2 The virus is transmitted from person to person, mainly through direct contact or through virus-laden droplets propelled by the coughing or sneezing from an infected individual. 3 The Health-care workers in all areas worldwide are facing a major challenge, as they are particularly exposed to various stressors during the pandemic. 4 The ones who are in quarantine need to reconcile their domestic responsibilities with studies or work, often under more stressful conditions due to family life, especially for those with children. 6 Those who remain at work, however, need to deal with the fear of infecting themselves or their families, which leads to a permanent state of vigilance, and even exhaustion from wearing personal protective equipment (PPE). 4 Those on the frontline in hospitals face the need to use even more equipment, as they frequently deal with infected patients, besides the increased workload and constant work pressure. 8 During the SARS-CoV outbreak in 2003, most health-care workers experienced high levels of symptoms of stress, anxiety, and depression. 9,10 Despite protective measures, professionals were infected with SARS during aerosol-generating procedures. 11 Hence, dental professionals who are strongly exposed to it during dental procedures may be quite susceptible to SARS-CoV-2 contamination due to clinical practice. 12 Moreover, it has been shown, among health-care professionals, dentistry has one of the highest levels of stress load and risk of developing musculoskeletal disorders, such as temporomandibular disorders (TMD). 13,14 TMD is defined as a series of clinical problems involving the masticatory muscles, the temporomandibular joint (TMJ), and associated structures. 15 It is one of the musculoskeletal conditions that mostly results in pain and disability, and the most frequent condition of chronic orofacial pain. 16 Psychosocial factors and sleep disorders are known to contribute to the perpetuation of TMD pain 17 and some studies demonstrate a positive association between TMD and bruxism. 18,19 Also, psychosocial factors were related to increased masticatory muscle activity in awake bruxism. 20 Furthermore, stress and anxiety can also affect the quality of life and sleep of individuals. 1,21 Therefore, this study aims to verify sleep quality, psychological aspects, reports of bruxism, and TMD symptoms in Brazilian dentists (DSs) who were on the frontline in hospitals, in outpatient care, and quarantined at home during the COVID-19 pandemic.
The first hypothesis was that dentists who were on the frontline would have a high prevalence of sleep disorders, psychological changes, TMD symptoms, and bruxism (H1). The second hypothesis was the existence of an association between concerns regarding the pandemic and their working status with psychosocial aspects, sleep quality, TMD symptoms, and bruxism (H2). The third hypothesis was the existence of a positive correlation between sleep quality and psychosocial aspects in different groups (H3).  The Depression, Anxiety, and Stress Scale (DASS-21) in the Brazilian-Portuguese version 23 was used simultaneously to measure and distinguish depression, anxiety, and stress symptoms. Its items are divided into three factors (depression items : 3, 5, 10, 13, 16, 17, 21; anxiety items: 2, 4, 7, 9, 15, 19, 20; and stress items: 1, 6, 8, 11, 12, 14, 18). The responses to them range from 0 (does not apply to me at all) to 3 (applies to me very much or most of the time).

Results
The sample of this study was composed of 641 dentists (age 39 years old ± 10.56, 74% female, 61.2% married) who answered the online questionnaire. The exclusion of some individuals who sent the form in duplicate caused a loss of 22 questionnaires (3% of the sample). Among the participants, 208 were quarantined (G1), 401 in outpatient care (G2), and 32 on the frontline in hospitals (G3). There was no statistically significant difference regarding gender among groups (p=0.083) ( Table 1).
When asked about the level of concern regarding the current pandemic, 92.3% of the respondents were moderate to extremely worried (Table 1). TMD symptoms were seen in 24.3% (n=156) of them, with no significant difference among groups (p=0.86) ( Table 2). The self-reported bruxism in the sample was 58.03% for sleep bruxism (SB) and 53.82% for awake bruxism (AB), with no considerable difference among groups (p=0. 33, p=0.79, respectively). Regarding sleep, 93.4% of the participants had a score above 5 in the PSQI questionnaire, which could be classified as poor sleep quality with no difference among them (p=0.72) ( Table 2). The PSQI mean score and standard deviation for the groups were 9.60 (3.09), 9.51 (2.98), and 9.13 (2.68) for quarantined (G1), outpatient care (G2), and frontline in hospitals (G3), respectively.
Stress symptoms had a similar distribution among the studied groups, with no significant difference (p=0.127), as well as anxiety (p=0.208). For depressive symptoms, those who were quarantined had more symptoms, but the significant difference occurred only with the outpatient/office care group (p=0.002; Bonferroni adjustment p<0.016) ( Table 3).
There was also a significant correlation between   To find relations between the dependent variables (anxiety, stress, depression, TMD screening, subjective sleep quality, possible sleep, and awake bruxism) and independent variables representing the pandemic (specific working status during the pandemic and concerns about it), the first block of models was designed (Table 4). It was noticed that DSs who were actively working were significantly (p=0.001) less likely (OR=0.630) to have symptoms of depression than those who were quarantined.
It was also observed individuals who declared they were not worried or little worried about the pandemic had a lower chance of showing symptoms of stress (OR=0.360), anxiety (OR=0.255), and poor sleep (OR=0.256) in a significant way (p=0.014, p=0.002, p<0.001, respectively). TMD pain symptoms, selfreported awake, and sleep bruxism were directly associated with the depression, stress, anxiety symptoms, and sleep quality variables. They were also indirectly related to the pandemic variables (specific working status during the pandemic and concerns about it), either as a protective factor (in absence of the symptoms, there was a reduction in the number of chances of presenting the assessed condition) or a risk factor (the presence of the element increases the chances of the pathology) ( Table 5).    A high number of participants were worried about the pandemic, representing more than 90% of the sample. This concern is not uncommon in the current moment, once most people have undergone major changes in their routines, dealing with insecurities about their health, duration of the pandemic, and financial situation, in face of this new reality. 6

Discussion
The COVID-19 pandemic affects both the physical and mental health of individuals, 9,26,27 with healthcare workers being particularly subjected to various stressors, which may lead to higher levels of emotional distress. 4 Shacham, et al. 28 (2020) found an elevated risk of psychological distress in 11.5% (n=39) of the dentists evaluated in Israel during the COVID-19 pandemic. Huang,et al. 29 (2020)  Such results were similar to those found in the current study regarding symptoms of stress (30.3%, n=194) and anxiety (33.7%, n=216).
Depression symptoms were more frequent in dentists that were isolated in quarantine. Brooks, et al. 30 (2020) report quarantine can have a considerable impact on the mental health of the population. This fact may be related to the reduction of income and the decline in social relationships. Income uncertainty can contribute to psychological changes in individuals who are out of work as they begin to question their financial future. According to the United Nations, social isolation can be aggravated by the suffering caused by the loss of income and jobs (https://bit.ly/2XsafSl). 31 The quarantine can also cause greater stress due to the inability to engage in rewarding activities, 6 and the decrease in social relationships, which may exacerbate feelings of loneliness, being an important predictor for depression. 32 Moreover, the psychological impact of the quarantine is broad, and it can be longlasting, with long-term consequences, 30 associated with psychological symptoms. 33 Some studies indicate frontline professionals are more likely to present psychological changes. 9,34,35 Nevertheless, in this study, there was no significant  Participants without symptoms of depression, anxiety, and stress were less likely to report awake bruxism, which agrees with previous studies that demonstrate the relationship between awake bruxism and psychosocial factors. 45 Patients with high levels of stress may be almost six times more likely to report awake bruxism. 46,47 Moreover, dentists with poor sleep quality were statistically related to a greater chance of awake (p<0.001, OR=1.68) and sleep bruxism (p<0.001, OR= 1,79). Ahlberg, et al. 48 (2008) noticed a relationship between bruxism and sleep disorders, being significantly related to frequent awakenings.
Although not verified in this study, it is important to note the reporting of sleep bruxism may be associated with sleep disorders such as obstructive sleep apnea syndrome and insomnia. 49  Thus, based on the data presented and limitations of the study, it is essential to further research this topic, especially in a post-pandemic scenario, once symptoms may be aggravated over time, as observed in other situations. 5,30 Also, the high prevalence of sleep disorders and their relationship with TMD, bruxism, and emotional factors deserves concern and may negatively impact the quality of life of DSs.

Conclusion
In this study, dentists who were in quarantine had significantly more symptoms of depression, suggesting confinement may have a more negative impact on the lives of these professionals than the fact that they are actively working, despite the risks. The concern about Covid-19 was quite prevalent, being related to Association of sleep quality and psychological aspects with reports of bruxism and TMD in Brazilian dentists during the COVID-19 pandemic J Appl Oral Sci. 2021;29:e20201089 9/10 anxiety, stress, and poor sleep quality. Also, the high prevalence of sleep disorders and their relation to TMD, bruxism, and emotional factors deserve attention and can negatively affect the quality of life of the study population. Thus, further research is needed, especially in a post-pandemic scenario, since the symptoms may worsen over time.

Conflicts of interest
There are no conflicts of interest.