Temporomandibular disorders and associated comorbidities among brazilian dental students during COVID-19

Abstract

Aim

This study aimed to assess the prevalence of temporomandibular disorders (TMD) and psychosocial comorbidities in undergraduate dental students in a southern Brazilian university, during the COVID-19 pandemic. Also, it aimed to verify the association between psychosocial factors and TMD.

Methods

Fonseca Anamnestic Index, Depression Anxiety Stress Scale (DASS-21), a socioeconomic questionnaire, and questions about academic performance and social distancing were applied. Poisson regression analysis was used to assess the association of predictive variables with TMD.

Results

The prevalence of TMD was found to be 82.4%, and more than half of the students had some degree of stress, anxiety, and depression. Students who had symptoms of stress (RR 1.11; 95% CI 1.04-1.19), anxiety (RR 1.19; 95% CI 1.12-1.27) and reported academic performance worsening (RR 1.12; 95% CI 1.07-1.19) had higher TMD scores.

Conclusion

The findings suggest that TMD was highly prevalent among dental students at a federal university in southern Brazil during the pandemic, being associated with high levels of stress, anxiety, poor academic performance, and greater social distancing.

COVID-19; Temporomandibular joint disorders; Depression; Anxiety

Introduction

Temporomandibular disorders (TMD) encompass a group of multifactorial conditions that cause pain and/or loss of function of the masticatory muscles, temporomandibular joint (TMJ), and associated structures¹. Scientific evidence indicate a relationship between TMD and psychosocial aspects, such as stress, anxiety and depression²,³, being the last both highly associated with painful TMD³.

Undergraduate students have high stress levels and feel greater distress than the general population, which leads to a high prevalence of mental health problems and greater risk for psychopathological problems⁴. Intense pace of life, increased hours of study, and geographical distance from family and friends might provoke feelings such as disappointment, irritability, concern, and impatience⁵. In addition, several studies have shown that stress levels among dental students are significantly higher when compared to students from other undergraduate programs⁶. This may be related to a complex curriculum that involves theoretical learning, clinical practice, and patient care⁷, being a possible reason why most dental students report symptoms that are already identified as risk factors for TMD and pain conditions⁸.

On March 11, 2020, the World Health Organization (WHO) declared the COVID-19 pandemic, caused by the SARS-CoV-2 virus⁹. Due to its high contagion, in the absence of mass vaccination the most effective means of controlling virus propagation was practicing social distancing¹⁰. Therefore, factors that generate stress may be increased during the COVID-19 pandemic. In this sense, the suspension of in-person activities, such as classes, for an indefinite period, as well as the excess of negative information may trigger important psychological disorders¹¹. In addition, the adoption of a remote educational model can lead to several access difficulties that can also be considered stressful and generate anxiety in this period¹².

The stress present in a daily routine during a pandemic might cause damage to health, that is, it can contribute to the development of TMD, depression, anxiety, and stress. Thus, this study aimed to verify the prevalence of these pathologies in undergraduate dental students at Federal University of Santa Maria (UFSM), as well as to analyze the association between TMD and the presence of comorbidities, academic performance, and social distancing, during the COVID-19 pandemic. The conceptual hypotheses were: 1) the prevalence of TMD is high among dental students at UFSM; 2) the highest occurrence of TMD is associated with high levels of stress, anxiety, and depression; 3) the highest occurrence of TMD is associated with worse academic performance and greater social distancing.

Materials and Methods

This is a cross-sectional observational study carried out on dental students in the city of Santa Maria, southern Brazil. Federal University of Santa Maria is a Higher Education Institution located in Santa Maria, in which 25,951 students are enrolled. It has a teaching staff composed of 2,020 teachers and offers 266 undergraduate programs. In March 2020, in-person classes were suspended due to the beginning of the COVID-19 pandemic in Brazil and were replaced by remote education until this date. All 343 students enrolled at the Dentistry undergraduate program were invited to participate in this study. The volunteer participants filled out a digital questionnaire on Google Forms platform. Data collection was carried out in the period between August 11 and November 20, 2020, when the questionnaire was available on Google Forms. Students were invited to participate in the survey via social networks, email, and WhatsApp messaging application.

The sample size was calculated considering the following parameters: 5% sampling error, 95% confidence interval (CI), finite population of students enrolled in the UFSM Dentistry undergraduate program (estimated 350 students), and the expected prevalence of TMD (50%). Adding 20% for possible losses, the minimum sample size required was 221 individuals. Prevalence value of 50% was used when the prevalence of the phenomenon in question was unknown in some context, for example. The value of 50% gave the biggest possible size of the necessary sample¹³.

The questionnaire was composed of the Fonseca Anamnestic Index (FAI)¹⁴; Depression, Anxiety and Stress Scale (DASS-21)¹⁵; questions regarding academic performance and social distancing during the COVID-19 pandemic; and a demographic and socioeconomic questionnaire.

The FAI¹⁴ was used to assess the presence of TMD. This index consists of 10 questions: 1) “Do you have difficulty opening your mouth wide?”; 2) “Do you have difficulty moving your jaw to the sides?”; 3) “Do you feel fatigue or muscle pain when you chew?”; 4) “Do you have frequent headaches?”; 5) “Do you have neck pain or a stiff neck?”; 6) “Do you have ear aches or pain in that area (temporomandibular joint)?”; 7) “Have you ever noticed any noise in your temporomandibular joint while chewing or opening your mouth?”; 8) “Do you have any habits such as clenching or grinding your teeth?”; 9) “Do you feel that your teeth do not come together well?”; 10) “Do you consider yourself a tense (nervous) person?”. Each question has three possible answers: “yes”, “no”, or “sometimes”, which are assigned values of “10”, “0”, and “5”, respectively. The total sum of these values classifies the severity of TMD: “absence of TMD” (0-15), “mild TMD” (20-40), “moderate TMD” (45-65), and “severe TMD” (70-100). This index is one of the few instruments available in the Portuguese language that is able to assess TMD severity. Despite being very sensitive to identifying TMD patients, it has low specificity in identifying non-TMD individuals, being recommended for screening of patients¹⁶. In the present study, the total scores of the TMD questionnaire were used. Thus, the higher the questionnaire score, the greater the severity of TMD.

Stress, anxiety, and depression levels were assessed using the reduced version of the Depression, Anxiety and Stress Scale (DASS-21), validated for the Brazilian population¹⁵,¹⁷. It consists of three subscales of seven items each, which aim to assess depression, anxiety, and stress experienced by the individual in the past seven days. The answers to each question are reported on a Likert scale, ranging from “strongly disagree” (0) to “strongly agree” (3). The overall scores for the three components are calculated by the sum of the scores of the 7 relevant items multiplied by two. The scoring ranges correspond to the levels of symptoms, ranging from “normal” to “extremely severe”¹⁵. In the analysis, the presence of stress, anxiety and depression was dichotomized into “absent” (normal) or “present” (scores considered medium, moderate, severe, or extremely severe).

Regarding academic performance, a question about self-perceived performance was used: “During the pandemic, do you consider that your academic performance: 1) has improved, 2) has remained the same, 3) has worsened”. In the analysis, the variable was dichotomized into “remained the same/improved” (scores 1 and 2) and “has worsened” (score 3). The attitude towards social distancing during the pandemic was also assessed: “Regarding the social distancing that is being guided by health authorities, that is, staying at home and avoiding contact with other people, how much do you think you are managing to do?”, with the following possible answers: 1) Practically isolated; 2) Isolated enough; 3) More or less isolated; 4) Little isolated; 5) Very little isolated¹⁸. For the analysis, the variable was categorized as very isolated (scores 1 and 2) and more or less/little/very little isolated (scores 3, 4 and 5).

The demographic and socioeconomic variables assessed were gender (female and male), age, skin color (white and non-white), income, and family structure (living alone or with other people). The age was collected in years and later dichotomized according to the median into ≤21 years or >21 years. The monthly income was collected in Real (Brazilian currency; 1.00 US dollar corresponds to 5.13 reais) and later dichotomized by the median of ≤5000 or >5000 reais per month. The period (semester) in which the student was enrolled in was also considered for the analysis.

Data analysis was performed using STATA 14.0 program (StataCorp. 2014. Stata Statistical Software: Release 14.0. College Station, TX: StataCorp LP). A descriptive analysis of the demographic, behavioral, and clinical characteristics of the sample was carried out. Unadjusted and adjusted Poisson regression analysis was used to assess the association between the predictor variables and the total TMD scores. The predictor variables that presented a p-value <0.20 in the unadjusted analysis were considered in the adjusted model. The results are presented as a Rate Ratio (RR) and a 95% confidence interval (95% CI). Poisson regression analysis was used in our study for modeling count data, as recommended by previous literature for this approach¹⁹,²⁰.

All procedures were in accordance with the ethical standards. The study protocol was approved by the Institutional Ethics Committee of Federal University of Santa Maria (date of approval: August 2020; approval number: 34721820.0.0000.5346). All participants signed an informed consent form.

Results

From 343 students enrolled in the Dentistry undergraduate program at UFSM in August 2020, 222 participated in this study (response rate of 64.72%). The sample included students from all semesters, with an average of 22 years of age (standard deviation [SD] 2.9). Among the assessed individuals, 74.3% were female and 82.4% were white. Regarding the socioeconomic level, 53.3% belonged to families whose monthly income was up to 5000 reais. The suggested prevalence of TMD was found to be 82.4%, and the mean score was 37.1 (SD 18.8). Most students had some degree of stress, anxiety, and depression (57.5%, 54.2%, and 58.6%, respectively) (Table 1).

Table 1
Distribution of demographic, socioeconomic, and clinical characteristics of students in the Dentistry undergraduate program at UFSM (n = 222).

Variables	N*	%
Demographic and Socioeconomic variables
Gender
Female	165	74.3
Male	57	25.7
Age
≤ 21 years	116	52.3
> 21 years	106	47.7
Skin color
White	183	82.4
Non-white	39	17.6
Monthly income (in Reais)a
≤ 5000	116	52.3
> 5000	106	47.7
Dwelling situation
Living alone	25	11.3
Living with other people	197	88.7
Semester of dental course
1st – 5th	111	50.0
6th – 10th	111	50.0
Behavioral and psychosocial characteristics
Social distancing during the COVID-19 pandemic
Very isolated	141	63.5
More or less/little/very little isolated	81	36.5
How do you consider your academic performance before the COVID-19 pandemic?
Same/Better	55	24.8
Worse	167	75.2
Stress
Absent	95	42.8
Present	197	57.2
Anxiety
Absent	101	45.5
Present	121	54.5
Depression
Absent	92	41.4
Present	130	58.6
TMD classification
Absent	39	17.6
Mild	92	41.4
Moderate	78	35.1
Severe	13	5.9
TMD score (mean [SD])	37.1 (18.8)

• *Values less than 222 are due to missing data; ^a1 USD corresponds to 5.60 reais. SD, standard deviation; TMD, temporomandibular disorder.

Table 2 shows the unadjusted and adjusted association between the predictor variables and the total TMD scores during the COVID-19 pandemic. In the unadjusted analysis, sex, age, social distancing, academic performance during the pandemic, stress, anxiety, and depression were associated with the total TMD scores (p <0.05). In the adjusted analysis, only depression lost association with TMD. Male individuals had TMD scores 18% lower (RR 0.82; 95% CI 0.77-0.86) than females. In addition, individuals over the age of 21 presented about 10% higher degrees of TMD (RR 1.10; CI 95% 1.05-1.15) than their counterparts. Considering behavioral characteristics, students who performed low social distancing presented TMD scores 16% lower than individuals that performed high isolation (RR 0.84; 95% CI 0.80-0.88). Dental students who had a worse academic performance showed higher TMD scores (RR 1.12; 95% CI 1.07-1.19). Considering the psychosocial characteristics, the presence of stress (RR 1.11; 95% CI 1.04-1.19) and anxiety (RR 1.19; 95% CI 1.12-1.27) symptoms were responsible for 11% and 19% higher scores of TMD among students during the pandemic, respectively.

Table 2
Unadjusted and adjusted association between the predictor variables and the total TMD scores, determined by Poisson regression.

Variables	Unadjusted RR (CI 95%)	p-value	Adjusted RR (CI 95%)	p-value
Demographic and socioeconomic variables
Gender		<0.01		<0.01
Female	1.00		1.00
Male	0.76 (0.72-0.80)		0.82 (0.77-0.86)
Age		<0.01		<0.01
≤ 21 years	1,00		1.00
> 21 years	1.06 (1.02-1.11)		1.10 (1.05-1.15)
Skin color		0.787	-
White	1,00
Non-white	1.02 (0.85-1.22)
Monthly income (in Reais)		0.325	-
≤ 5000	1.00
> 5000	1.06 (0.93-1.22)
Dwelling situation		0.394	-
Living alone	1.00
Living with other people	1.09 (0.88-1.36)
Semester of dental course		0.901	-
1st – 5th	1.00
6th – 10th	1.00 (0.88-1.15)
Behavioral and psychosocial characteristics
Social distancing		<0.05		<0.01
Very isolated	1.00		1.00
More or less/little/very little isolated	0.83 (0.72-0.96)		0.84 (0.80-0.88)
Academic performance		<0.01		<0.01
Same/Better	1.00		1.00
Worse	1.15 (1.09-1.21)		1.12 (1.07-1.19)
Stress		<0.01		<0.01
Absent	1.00		1.00
Present	1.34 (1.28-1.40)		1.11 (1.04-1.19)
Anxiety		<0.01		<0.01
Absent	1.00		1.00
Present	1.35 (1.29-1.41)		1.19 (1.12-1.27)
Depression		<0.01		0.098
Absent	1.00		1.00
Present	1.28 (1.23-1.34)		1.05 (0.99-1.12)

• *TMD, temporomandibular disorder; RR = rate ratio; CI = confidence interval; a1 USD corresponds to 5.60 reais.

Discussion

During a pandemic, many studies on the biological risk of the disease or on the pathogen are developed, but it is also necessary to pay attention to psychosocial aspects. These generally tend to be neglected and can cause several disorders²¹,²², such as stress, anxiety, and depression, which can lead to the development of TMD¹¹. In addition, patients with TMD have a higher level of anxiety and depression than the general population²³. Thus, the findings of this study partially suggest the confirmation of its conceptual hypothesis, because in the unadjusted analysis TMD was associated with stress, anxiety, depression, and low academic performance, whereas in the adjusted analysis, depression lost association with TMD.

The findings suggest that the prevalence of TMD in undergraduate dental students at UFSM during the COVID-19 pandemic was high (82.4%), higher than previous studies with undergraduate students that also used the FAI to assess prevalence of TMD, ranging between 53.2% and 66.3%²⁴-²⁶. In a study carried out in Saudi Arabia that also used the FAI, the prevalence of TMD in dental students before the COVID-19 outbreak was 49.9% and a positive association was reported between the level of perceived stress and anxiety and tone of both masseters²⁷. During the pandemic, a cross-sectional study²⁸ found the prevalence of TMD to be 77.5%, corroborating our findings. On the other hand, another recent study²⁹ found the prevalence of symptoms of TMD to be only 27.4%, which can be partially explained by the low percentage of individuals that were performing greater social isolation in the sample (21.2%).

Based on the findings of this study, this high prevalence of TMD might be an effect of stressors caused by the pandemic, which intensify the symptoms of bruxism and TMD¹¹,³⁰, as well as the difficulty of access and consequent learning during remote education³¹. In addition, students who reported worse academic performance had higher TMD scores, which suggest the confirmation of the hypothesis raised. Moreover, it was observed that individuals who performed greater social distancing had higher levels of stress and, consequently, probable higher TMD scores. During the pandemic, social distancing is necessary to mitigate contamination³², although it is associated with negative psychological effects, such as post-traumatic stress, confusion, and anger, mainly due to prolonged isolation, frustration, boredom, and fear of infection³³. Social isolation also leads to a decrease in the practice of physical activity; those who exercised during the pandemic had 13% lower levels of stress³⁴. Therefore, the stress levels during the pandemic influence the development of TMD (or its worsening in those individuals who already had the disorder)²⁸ and might also lead to greater depressive and painful symptoms³⁵.

Some of the main side effects caused by the COVID-19 outbreak are high anxiety and depression levels, due to great exposure to negative news, fear of contagion, unemployment, and the loss of loved ones³⁶.More than half of the study sample self-reported stress, anxiety, and depression. Two metanalyses found divergent prevalences of anxiety³⁷ and depression³⁸ on dental students during the post-pandemic period, ranging from 26-45% and 26-49%, respectively. Regarding Brazilian dental students, a cross-sectional study found that 31.3%, 29.6%, and 24.2% of students had mild, moderate, and severe anxiety symptoms, respectively, totalizing 85.1% of the study sample³⁹. Before the COVID-19 outbreak, the prevalence of anxiety and depression ranged from 24% to 50.5%²⁷,⁴⁰ on dental students, similar to the findings after the pandemic, possibly explained by the extensive curriculum of this undergraduate program, involving theoretical learning, clinical practice, and patient care⁷.

Considering the gender of the students, females presented higher TMD scores. Studies also point out that the occurrence of TMD is twice as common among women⁴¹, and that psychological overload during the pandemic is greater in female individuals⁴². Also, individuals who were over 21 years of age presented higher TMD scores. This age group is closer to graduation, with additional stressors such as concerns about the future and the labor market⁴². The literature considers that the peak of development of TMD occurs between 20 and 40 years of age⁴³, which corroborates the findings of the present study.

This is the first study to assess the impact of the COVID-19 pandemic on the prevalence of TMD among undergraduate dental students in the south of Brazil. In addition, this study used validated instruments for the diagnosis of TMD and comorbidities. The Depression, Anxiety and Stress Scale questionnaire is a method of easy reproducibility and data collection without the examiner’s influence. Another positive aspect is its representative sample of undergraduate dental students at UFSM, which allowed the analysis and extrapolation of findings.

Some limitations of this study must be recognized. The fact that it was a cross-sectional observational study did not allow any causal relations. Therefore, future studies are suggested to assess causality, following participants until a change in the pandemic scenario occurs. Besides, the study used a digital questionnaire, thus no clinical examinations were performed and therefore the origin of the TMD (myogenous or arthrogenous) could not be assessed. Lastly, even though more complete instruments for the diagnosis of TMD are available (e. g., the Diagnostic Criteria for Temporomandibular Disorders - DC/TMD)⁴⁴, the FAI is a very sensitive index in identifying TMD patients (despite its low specificity in identifying patients who do not have TMD), recommended for patient screening. Furthermore, this instrument has already been used in previous studies that evaluated TMD⁴⁵-⁴⁷.

Sociodemographic variables should also be considered when interpreting the results. Even though all students were invited to participate, some biased answers toward those who were concerned with their oral health or who wanted to participate in research projects might be seen. Participants’ age is another relevant issue. Since this study evaluated undergraduate students, other studies might observe a different impact of the pandemic in older subjects. In addition, questions about academic performance and social distancing were created for this study, and their results reflect the students’ self-report. However, the findings are extremely relevant to the academic environment. This study can be taken as a warning to other educational institutions, in view of its findings. Mental health care should be emphasized by the University, based on activities that encourage self-care and dialogue strategies with students. This is essential because, as demonstrated in this study, students are stressed, anxious, and with a high prevalence of TMD. As a result of these problems, the performance and development of daily activities are affected.

In conclusion, the findings of this study suggest a high prevalence of TMD (82.4%) among dental students at UFSM during the COVID-19 pandemic. TMD was associated with high levels of stress, anxiety, poor academic performance, and greater social distancing. Furthermore, women and individuals over the age of 21 were more likely to have higher TMD scores.

Acknowledgements

The authors wish to thank the undergraduate students who helped with data collection.

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• Data availability
• The authors declare that data is unavailable to access.

• Funding: None.

Edited by

Editor: Dr. Altair A. Del Bel Cury

Publication Dates

• Publication in this collection
  16 Jan 2023
• Date of issue
  2023

History

• Received
  27 Oct 2021
• Accepted
  09 Oct 2022