Results

Figure 1 is a flowchart of the search and selection procedure for articles based on PRISMA 2020 guidelines. According to the SIGN checklist, cohort studies are acceptable and case-control studies are of good quality, while all selected publications are acceptable according to the JBI checklist. All ten studies from the selected databases meet the age requirement of 18 years old. Two of the ten studies have descriptive cross-sectional study designs, seven has case-control study research designs, and one has retrospective cohort study designs. RDC/ TMD was utilized to assess and diagnose TMD in six of the investigations, RDC/TMD and Fonseca Index in one study, and FAI index in one study (Fonseca Anamnesis Index).

Figure 1: PRISMA 2020 flowchart.

Discussion

This review covers ten articles that studied the association between mental stress and bruxism. The results showed that stress has a direct effect causing bruxism, whether it was in children, as the stress coping strategies or as a result of depression. Some articles also discussed stress effect at the cellular level through biomarkers.

Two of the articles included in this review had some associations related to children. A study conducted by Negra, et al. studied the relationship between stress and children’s personalities and its influence on bruxism. The study included 360 participants with equal numbers of both sexes and mean age of 9 years. The sample was divided to bruxers (n=120) and non-bruxers (n=240). Mental stress was assessed by phycologists using some tests, while bruxism was assessed by reports made by parents. Children with high levels of stress and responsibilities had a higher chance of bruxism. So this study concluded that stress and responsibility has an influencing effect on bruxism [9].

Study done by Sampaio, et al. studied if stress has an effect of bruxism in both children and their mothers. It included 48 (36 males, 40 females) participants, with mean age of 24 years. The study included a questionnaire for sociodemographic identification and to asses’ stress. Clinical examination was also done to evaluate wear in teeth. Results included that there was no relationship between demographics and bruxism, while there was increased prevalence of bruxism in children when the mothers are also bruxers. As for this study it concluded that there is no association between demographics and bruxism for both children and mothers [11-14].

According to the authors, we can conclude that stress have an effect in causing bruxism. This finding correlates with the recent findings of Alvarez, et al. bruxism in children will have an increased prevalence when mothers are bruxers. The most distinctive signs and symptoms for bruxism are dental wear and headaches, which related to anxiety, stress and behavior problems mainly due to emotional changes that occur during childhood thus altering sleep quality and aid in the development of bruxism [15].

Other studies agree with stress causing bruxism, but also discussed other aspects of this topic. Gomes, et al. looked into separation anxiety being another risk factor for developing bruxism, which is usually a reaction to stress that happen in 12-18 months children whom are separated from their caregivers thus both physical and emotional attachment is disrupted. Same thing occur in their mothers psychological characteristics change causing stress and depression, thus this will have an effect on the children to present bruxism. Even though bruxism severity in children might be of lesser degree than adults, their teeth wear is more intense as the characteristics of primary teeth exhibit a less mineralization compared to permanent teeth [16].

Two articles investigated the effect of stress and its coping strategies on the development of bruxism. Saczuk, et al. included 60 (17 males, 43 females) participants with mean age of 30 years, and were grouped as bruxers (n=35) and nonbruxers (n=25). They have studied the relationship between bruxism, stress and coping mechanism. Bruxism was assessed by clinical examination and by use of Bruxo overnight. Stress was assessed by Perceived Stress Scale (PSS-10), while coping mechanism by Brief-COPE. There was a significant relation between stress and bruxism. The type coping strategy done by stressed individuals, it may increase the chance of bruxism [13].

As for second study, it was conducted by Giraki, et al. and it included 69 (23 males, 46 females) participants with mean age of 29 years. The study investigated if stress factors corelate with bruxism. Participants answered a questionnaire to asses stress and coping mechanism. Bruxism was assessed by a monitoring device, Bruxcore. Both questionnaire and device analysis corelated significantly with bruxism. The study concluded that the as problems increase, stress levels will also increase, thus having an impact on teeth wear by bruxism [7].

These findings comply with a study conducted by Gungormus, et al. that proposed that certain personality characteristics such as stress and anxiety are primary psychological factors responsible for the development of bruxism in both children and adults [17], were as Saczuk, et al. found that participants who use Self-Blame as a coping mechanism achieved the highest bruxism score [18]. It was also reported by a study conducted by Zadworna, et al. that choosing Self-Blaming is the strongest predictor of perceived stress [19].

Other two articles correlated stress and psych with bruxism. A study conducted by Manfredini, et al. studied the correlation between bruxism and psychic factors. The study included 85 (47 males, 38 females) participants with mean age of 25 years and were grouped in bruxers (n=34) and non-bruxers (n=51). A questionnaire was distributed to the participants to assess mood (MOODSSR) and panic agoraphobic (PASSR) spectra, while teeth were evaluated clinically. The study concluded with the presence of some psychic traits in bruxers. Stress have an effect on psych thus the higher the chance of bruxism, but it’s difficult to differentiate bruxers and nonbruxers based only on dentition [5].

While a study conducted by Smardz, et al. has studied the relationship between stress and depression symptoms and bruxism. It included 77 (21 males, 56 females) participants, that were divided into two groups bruxers (n=58) and nonbruxers (n=19). The participants experienced video-polysomnography to evaluate stress and any depressive symptoms occurred. The study concluded with that there was no significant correlation between stress, depression and intensity of bruxism when compared between bruxers and nonbruxers [12].

These findings correlated with a study done by Flueraşu, et al. which indicated a statistically proven involvement of psychological factors in the occurrence of bruxism. Stress and anxiety can be favorable factors in the appearance of both types of bruxism; however, depression was associated only with awake bruxism [20].

Most of the articles included in this review, six articles investigated stress within salivary biomarkers and its relation to bruxism. A study conducted by Makino, et al. to explain the correlation between stress salivary biomarkers level and its relation to bruxism. The study included 46 (23 males, 23 females) participants. A questionnaire, diagnostic casts and BiteStrip to assess bruxism. Saliva was also collected to measure CgA levels. Dentition wear was associated significantly with questionnaire and BiteStrip scores, while CgA level was not significantly associated with bruxism [6], while a study conducted by Abekura, et al. aimed to examine if there was any relation between bruxism and psychological stress. The study included 76 participants (36 males, 40 females) with mean age of 24 years. The sample was divided into two groups bruxers (n=22) and non-bruxers (n=54). Bruxism was assessed by measuring levels of CgA and by use of visual analog scale (VAS). The mean salivary CgA levels of the nonbruxism group were not significantly increased after the stress task. While CgA levels of the bruxism group were increased significantly after the task. Thus the study concluded that there is a correlation between bruxism and psychological stress [8].

Another study conducted by Karakoulaki, et al. evaluated the association between stress and bruxism by assessing stress salivary biomarkers. The study included 45 participants (20 males, 25 females) with mean age of 35 years. Bruxism was determined by BiteStrip, where in cortisol and α-amylase levels in liva was also evaluated. There was a correlation between BiteStrip scores and the salivary cortisol levels within bruxers whereas salivary α-amylase level was nonsignificant between bruxers and nonbruxers. The study concluded that as the psychological stress and cortisol level increase, there will be higher chance of bruxism [10].

Fluerașu, et al. studied the association between salivary cortisol, psychological state and bruxism. 60 individuals (27 males, 33 females) participated in this study with mean age 23 years. Clinical examination of teeth wear, questionnaire to asses psychological state and salivary cortisol level was measured. Participants who had bruxism were characterized with stress. Cortisol level was higher in participants with bruxism. So this study concluded that bruxism is corelated with psychological state such as stress, as well as cortisol level, but is not a definitive marker for its severity [14].

Many studies agree with the theory that salivary biomarkers is a predisposing factor for bruxism. As a study conducted by Kobayashi, et al. stated that stress is a determinant of bruxism and can be measured by some biomarkers such as cortisol and alpha amylase. These biomarkers are usually elevated in stressed patients and present TMJ issues. Anxiety usually over-activates the hypothalamic, pituitary, adrenal glands thus increasing cortisol levels [21].

Based on the reviewed literature, bruxism will be classified at the time of examination as awake bruxism, sleep bruxism, and nonbruxism. The three groups can yield distinct study outcomes and conclusions. Literaturebased TMD diagnosis and screening techniques result in a number of diagnostic variants. Literature demonstrated that sleep bruxism could increase the likelihood of TMD and lead to the development of other diseases, including TMD discomfort, chronic migraine, cervical muscle pain, and headache.

Articles reveal that the most often studied types of bruxism are sleep bruxism and awake bruxism. In the reviewed literature, the analysed participants are at least 18 years old, and the prevalence of sleep bruxism in the adult age group (18-60 years) was reported to be 56.8 percent, with a higher frequency in women than in men. 11 Examining and determining the presence or absence of sleep bruxism can be accomplished by a variety of methods, including questionnaires, PSG, and EMG. In the examined literature, the majority of researchers employed questionnaires that are ideal for large sample sizes and can swiftly gather data from a large number of respondents in a short period of time, while one study employed EMG.

According to Manfredini, et al. [5] the diagnostic utility of questionnaires is contingent upon the patient's ability to differentiate between sleep and awake bruxism. However, the use of PSG and EMG is restricted due to high prices and the difficulty of examining large numbers of people. In screening, the ability of the operator or clinician to perform anamnesis and assess patient data using a questionnaire is vital.

Limitations

The articles involved in this systematic review had some limitations. The included articles discussed stress and bruxism in different aspects thus not being a specific study and altered statistical comparisons. Some studies have been designed with inadequate sample sizes or incomparable age and gender distributions. Bruxism was measured by different methods; some were subjective through self-reported questionnaire. Due to these limitations, it is recommended to do further studies of higher evidence-based, larger sample and randomization is needed. In addition, all other variables (such as: age, stress factors, coping strategy) needs to be standardized to confirm the results of this review. Not many articles described the relationship between mental stress and bruxism. Most included non-biased articles were case-control studies which could introduce a potential bias in the study outcomes and conclusions, so increasing number of cohort and clinical trials would make this review higher evidence-based study. Only two randomized controlled trials, and one cohort study was identified in this systematic review.

Conclusion

In conclusion, based on the available literature, mental stress is considered a predisposing factor that causes bruxism. It is of high importance to relieve this excessive clenching effect to further preserve the morphological and physiological teeth, periodontium and temporomandibular joint functions. This parafunction activity is more prevalent in adult patients and significantly more prevalent in women than in males. Bruxism and its management are a hot topic discussed among several academics and dentists. Therefore, updates and appraisals of the available evidence and literature are needed to sufficiently send information to healthcare providers. It is recommended to further educate the general population about bruxism, its causes and how to limit the risk factors associated with it through the national public health education programs.

References

1. Yost O, Liverman CT, English R, et al. Prevalence, impact, and costs of treatment for temporomandibular disorders. Temporomandibular disorders: Priorities for research and care. National Academies Press (US) 2020.
2. Yap AU, Chua AP. Sleep bruxism: Current knowledge and contemporary management. J Conserv Dent 2016; 19:383.

Indexed at, Google Scholar, Cross Ref

3. Shetty S, Pitti V, Satish Babu CL, et al. Bruxism: A literature review. J Indian Prosthodont Soc 2010; 10:141-148.

Indexed at, Google Scholar, Cross Ref

4. Blanco Aguilera A, Gonzalez Lopez L, Blanco Aguilera E, et al. Relationship between self‐reported sleep bruxism and pain in patients with temporomandibular disorders. J Oral Rehabil 2014; 41:564-572.

Indexed at, Google Scholar, Cross Ref

5. Manfredini D, Landi N, Romagnoli M, et al. Psychic and occlusal factors in bruxers. Aust Dent J 2004; 49:84-89.

Indexed at, Google Scholar, Cross Ref

6. Makino M, Masaki C, Tomoeda K, et al. The relationship between sleep bruxism behavior and salivary stress biomarker level. Int J Prosthodont 2009; 22.

Indexed at, Google Scholar

7. Giraki M, Schneider C, Schäfer R, et al. Correlation between stress, stress-coping and current sleep bruxism. Head Face Med 2010; 6:1-8.

Indexed at, Google Scholar, Cross Ref

8. Abekura H, Tsuboi M, Okura T, et al. Association between sleep bruxism and stress sensitivity in an experimental psychological stress task. Biomed Res 2011; 32:395-399.

Indexed at, Google Scholar, Cross Ref

9. Serra-Negra JM, Paiva SM, Flores-Mendoza CE, et al. Association among stress, personality traits, and sleep bruxism in children. Pediatr Dent 2012; 34:30.

Indexed at, Google Scholar

10. Karakoulaki S, Tortopidis D, Andreadis D, et al. Relationship between sleep bruxism and stress determined by saliva biomarkers. Int J Prosthodont 2015; 28.

Indexed at, Google Scholar, Cross Ref

11. Sampaio NM, Oliveira MC, Andrade AC, et al. Relationship between stress and sleep bruxism in children and their mothers: A case control study. Sleep Sci 2018; 11:239.

Indexed at, Google Scholar, Cross Ref

12. Smardz J, Martynowicz H, Wojakowska A, et al. Correlation between sleep bruxism, stress, and depression—a polysomnographic study. J Clin Med 2019; 8:1344.

Indexed at, Google Scholar, Cross Ref

13. Saczuk K, Lapinska B, Wilmont P, et al. Relationship between sleep bruxism, perceived stress, and coping strategies. Int J Environ Res Public Health 2019; 16:3193.

Indexed at, Google Scholar, Cross Ref

14. Fluerașu MI, Bocsan IC, Buduru S, et al. The correlation between sleep bruxism, salivary cortisol, and psychological status in young, Caucasian healthy adults. CRANIO 2021; 39:218-224.

Indexed at, Google Scholar, Cross Ref

15. Alvarez GG, Najera RI, Peñaloza R, et al. Sleep bruxism in children: An overview and current update. Int J Applied Dent Sci 2022; 8:11-15.

Google Scholar, Cross Ref

16. Gomes MC, Neves ET, Perazzo MF, et al. Evaluation of the association of bruxism, psychosocial and sociodemographic factors in preschoolers. Brazilian Oral Res 2018; 32.

Indexed at, Google Scholar, Cross Ref

17. Gungormus Z, Erciyas K. Evaluation of the relationship between anxiety and depression and bruxism. J Int Med Res 2009; 37:547-550.

Indexed at, Google Scholar, Cross Ref

18. Saczuk K, Lapinska B, Wawrzynkiewicz A, et al. Temporomandibular disorders, bruxism, perceived stress, and coping strategies among medical university students in times of social isolation during outbreak of COVID-19 pandemic. Healthcare 2022; 10:740.

Indexed at, Google Scholar, Cross Ref

19. Zadworna M, Michalska P, Kobylarczyk M. Stress and coping strategies among participants of stress management interventions at the science, technology and art festival. Educ Studies Rev 2020; 1:129-156.

Google Scholar, Cross Ref

20. Flueraşu MI, Bocşan IC, Țig IA, et al. The epidemiology of bruxism in relation to psychological factors. Int J Environ Res Public Health 2022; 19:691.

Indexed at, Google Scholar, Cross Ref

21. Kobayashi FY, Gavião MB, Marquezin MC, et al. Salivary stress biomarkers and anxiety symptoms in children with and without temporomandibular disorders. Br Oral Res 2017; 31.

Indexed at, Google Scholar, Cross Ref