Dentists' Stress During the COVID-19 Pandemic: A Repeated Cross-Sectional Study

Abstract

Objectives

Although studies have revealed that dentists’ mental health was initially affected by the COVID-19 pandemic, there are no reports on how this notion has evolved during the pandemic years. The aim of this study therefore was to compare Thai dentists’ stress prevalence and levels due to the pandemic over a three period of the pandemic, 2020, 2021, and 2022. The associated risk and protective factors were also investigated.

Methods

A questionnaire was distributed to Thai dentists via social media, that is, Facebook pages and Line groups, from April 24 through May 5, 2020, June 10 through 30, 2021, and April 10 through July 11, 2022. The Self-Administered Stress Evaluation Form-20 (SASEF-20) was used to evaluate the dentists’ stress levels.

Results

Higher stress levels and prevalence were found in 2021 and 2022 compared with 2020. Sex, age, religion, specialty, working status, and cash flow during the pandemic were identified as stress predictors.

Conclusion

The extended COVID-19 pandemic resulted in increased mental health deterioration. National and regional bodies overseeing dentists should be aware of vulnerable groups of dentists, such as younger dentists whose financial status might be unstable. Internet-based cognitive behavioural therapy may be a useful tool to reduce stress in this situation.

Introduction

The COVID-19 pandemic has severely affected the health care workers’ mental health. In the Asia-Pacific region, significant levels of psychological distress, including anxiety, depression, and burnout, have been reported.¹ Surgical providers familiar with COVID-19 fatalities were more vulnerable to depression, anxiety, stress, and posttraumatic stress disorder.² These findings suggest the need for a closer examination of the mental health issues facing health care professionals, including dentists.

An important part of mental health is stress. It is multifactorial and can improve or worsen over time.3, 4, 5 Many factors could affect dentists’ stress during the COVID-19 pandemic.^6,7 These factors include dentists’ sex, age, specialty, and income. Sex has been linked to mental health, but others are still unproven.8, 9, 10 Pharmaceuticals, vaccines, the rising number of infected people, and new viral strains may also stress dentists. These factors changed greatly between 2020 and 2022.

In 2020, 80 million individuals worldwide were infected without any accessible vaccines or therapies. The subsequent year saw a 2.5-fold increase in infection rates.¹¹ Whilst vaccination and treatment were being delivered, several COVID-19 mutant strains with increased virulence and decreased vaccine sensitivity arose.12, 13, 14, 15 In 2022, the infection rate was much greater.¹¹ More fetal and infectious strains continued to proliferate.¹⁶ Likewise, the number of immunised citizens increased.

It is unclear how these changes affected dentists’ stress levels year-to-year. From 2020 to 2022, dentists’ stress factors during COVID-19 are unknown. Thus, the primary goal of this study was to compare Thai dentists’ stress levels during the 2020–2022 time frame. The secondary goal was to identify stress-related risk or protective factors each year.

Materials and methods

This study is reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

Ethics and AI disclosure

This study followed the Declaration of Helsinki Ethical Principles for Medical Research Involving Human Subjects and approved by the Human Research Ethics Committee of the Faculty of Dentistry, Chulalongkorn University (#029/2020). During the preparation of this work, the authors used QuilBot (QuillBot Inc.) and ChatGPT (OpenAI Inc.) in order to improve the correctness and fluency of the language and to reduce the word count. After using this tool/service, the authors reviewed and edited the content as needed and took full responsibility for the content of the publication.

Sample size calculation

This study's population comprised dentists who were practicing in Thailand before the start of the pandemic. The sample size was calculated using the formula n = Z²pq/d².¹⁷ Using a 54.9% prevalence of stress in dentists from Collin et al¹⁸ with a 95% significance level, the calculated sample size was 381. By adding 20% in case of incomplete questionnaires, the sample size was at least 457 for each survey.

The questionnaire

A specific questionnaire was constructed using Google Forms. The questionnaire consisted of 3 parts: (1) The participants’ sociodemographic data and work and financial status; (2) the Self-Administered Stress Evaluation Form-20 (SASEF-20) developed by the Department of Mental Health, Ministry of Public Health, Thailand; and (3) the impact of COVID-19 sequelae on self-perceived stress levels, using a numeric rating scale ranging from 0 to 10 (see supplementary data 1).

SASEF-20 contains 20 items. Participants rated how often they had encountered a specific situation in each item during the last 2 months. The frequency was recorded as 0 = never, 1 = occasionally, 2 = frequently, or 3 = regularly. Based on the summed score of these items, stress was classified into 5 levels: 0 to 5 = hypo-stress, 6 to 17 = normal stress, 18 to 25 = mild stress above normal, 26 to 29 = moderate stress, and 30 to 60 = severe stress. When 17 points is used as the threshold to define normal stress, this test has 70.4% sensitivity, 64.6% specificity, and a Cronbach's alpha of 0.86.¹⁹

Data collection

The survey was conducted once each year. In 2020, the survey took place from April 24 through May 5, during Thailand's first pandemic and lockdown period (April 3–June 15, 2020). In 2021, the survey took place from June 10 through 30 (2 months after the third wave of the pandemic in Thailand). In 2022, the survey took place from April 10 through July 11 (4 months after the fifth wave of the pandemic in Thailand). The participants were recruited to the study through an announcement and short explanation about the study posted in private social media groups, that is, Facebook and Line. An incentive to participate was the chance to win one of twenty 500 THB (16 USD) Starbucks gift cards. This incentive has been shown to increase response rates by 73%.²⁰ The participants read the information concerning this study and gave their consent when responding to the questionnaire.

To confirm that the participant was a dentist, 2 screening questions were placed at the beginning of the questionnaire (supplementary data 2). Forms with wrong responses to the screening questions were excluded from the analysis. The participants who wanted to participate in the lucky draw were requested to confirm their intention at the end of the questionnaire. Then they were brought to a separate page where they could fill in their full name, phone number, and dentist registration number. These personal data were not linked to the questionnaire's responses; thus, the specific responses and participants’ identities could not be linked.

Statistical analysis

The participants’ characteristics were gathered as categorical data, and the stress levels were compared using the Pearson chi-square test. Ordinal data, such as income and expenses during the pandemic, were compared using the Mann–Whitney U test and Kruskal–Wallis test. Age, impact score of the COVID-19 sequelae, and stress score were compared using the Student t test and One-Way ANOVA. The age–stress correlation was tested using Pearson correlation. The odds ratios (ORs) for the independent variables and the stress levels were calculated using multiple logistic regression. The data were analysed using IBM SPSS version 22 (IBM Corp.).

Results

In 2020, 622 responses were received. Forty-two responses were excluded because 5 were not dentists, 5 were duplicates, and 32 were incomplete. Fewer responses (n = 499) were collected in 2021. Thirty-three responses were excluded because 25 were not dentists, 4 were duplicates, 3 were incomplete, and 1 was identified as choosing their responses at random. For 2022, 543 responses were received. Seventy-three were excluded because 57 were not dentists, 4 were duplicates, and 12 were identified as choosing their responses at random. Thus, 580, 466, and 470 responses from 2020, 2021, and 2022, respectively, were analysed.

Sociodemographic data

The sociodemographic data of the participants are shown in Table 1. Most characteristics were similar, except for age, religion, and working arrangement. The average participants’ ages in 2020 and 2021 were similar (38.39 ± 10.22 and 38.44 ± 9.22 years, respectively, P = .995), But they were significantly older than those in 2022 (36.03 ± 9.13 years, P < .001).

Table 1.

Participants’ sociodemographic data.

Demographics	2020		2021		2022		P value a
	n (N = 580)	%	n (N = 466)	%	n (N = 470)	%
Sex
Male	138	23.8	114	24.5	106	22.6	.801
Female	442	76.2	352	75.5	364	77.4
Religion
Buddhist	552	95.2	430	92.3	426	90.6	.025*
Christian	16	2.8	12	2.6	14	3.0
Other	12	2.1	24	5.2	30	6.4
Medical condition
No medical condition known	483	83.3	385	82.6	388	82.6	.778
Have medical condition	97	16.7	81	17.4	82	17.4
Education level
Bachelor's degree	254	43.8	217	46.6	224	47.7	.370
>Bachelor's degree	326	56.2	249	53.4	426	52.3
Main working field
Periodontist	26	4.5	21	4.5	20	4.3	.075
Operative dentist	20	3.5	7	1.5	14	3.0
Endodontist	46	7.9	33	7.1	26	5.5
General practitioner	247	42.6	212	45.5	230	48.9
Prosthodontist	61	10.5	47	10.1	48	10.2
Orthodontist	44	7.6	55	11.8	37	7.9
Oral surgery	74	12.8	55	11.8	65	13.8
Paediatric dentist	37	6.4	27	5.8	18	3.8
Others (eg, oral radiologist, oral pathologist, and geriatric dentist)	25	4.3	9	1.9	12	2.6
Primary working arrangement
Public hospital employee	235	40.5	142	30.5	178	37.9	<.001*
Dental school employee	115	19.8	83	17.8	75	16.0
Private hospital employee	53	9.1	24	5.2	24	5.1
Private dental clinic owner	64	11.0	76	16.3	49	10.4
Private dental clinic employee	113	19.5	138	29.6	144	30.6
Other	0	0.0	3	0.6	0	0.0
Secondary working arrangement
Public hospital employee	20	3.5	21	4.5	9	1.9	.038*
Dental school employee	36	6.2	34	7.3	39	8.3
Private hospital employee	52	9.0	40	8.6	42	8.9
Private dental clinic owner	44	7.6	48	10.3	45	9.6
Private dental clinic employee	232	40.0	161	34.5	207	44.0
No secondary working place	196	33.8	162	34.8	128	27.2
Primary working location
Bangkok	267	46.0	232	49.8	243	51.7	.227
Outside Bangkok	313	54.0	234	50.2	227	48.3

^aPearson chi-square.

^⁎P < .05.

Buddhist participants had the highest proportion in 2020 (95.2%), followed by 2021 (92.3%), and 2022 (90.6%), whilst Christian participants were stable amongst the years (2.8%, 2.6%, and 3.0% in 2020, 2021, and 2022, respectively).

Fewer participants were working in public hospitals in 2021 compared with 2020 and 2022 (30.5% vs 40.5%, P = .001 for 2021 vs 2020 and 30.5% vs 37.9%, P = .017 for 2021 vs 2022). In contrast, there were more dental clinic owners (16.3% vs 11.0%, P = .013 for 2021 vs 2020 and 16.3% vs 10.4%, P = .008 for 2021 vs 2022).

Working and financial status related to the COVID-19 pandemic

The working and financial aspects related to the pandemic during each year were different (Table 2). The percentage of participants working as normal during the pandemic continually increased from 2.1% in 2020 to 42.1% in 2021 and 96.4% in 2022, whilst the percentage of nonworking participants decreased from 42.6% in 2020 to 9.9% in 2021 and 0.2% in 2022.

Table 2.

Working and financial status related to the COVID-19 pandemic.

Characteristics	2020		2021		2022		P value a
	n (N = 580)	%	n (N = 466)	%	n (N = 470)	%
Working status during the COVID-19 pandemic
Working as usual	12	2.1	196	42.1	453	96.4	<.001*
Accepting only emergency and urgent cases	321	55.3	224	48.1	16	3.4
Not working	247	42.6	46	9.9	1	0.2
Income per month during the COVID-19 pandemic
<30,000 THB	267	46.0	82	17.6	51	10.9	<.001*
30,000–50,000 THB	141	24.3	97	20.8	92	19.6
50,000–80,000 THB	114	19.7	121	26	125	26.6
80,000–120,000 THB	42	7.2	78	16.7	103	21.9
120,000–200,000 THB	13	2.2	55	11.8	68	14.5
>200,000 THB	3	0.5	33	7.1	31	6.6
Expenses per month during the COVID-19 pandemic
<30,000 THB	253	43.6	147	31.5	160	34.0	.024*
30,000–50,000 THB	165	28.4	163	35	159	33.8
50,000–80,000 THB	91	15.7	87	18.7	84	17.9
80,000–120,000 THB	43	7.4	39	8.4	43	9.1
120,000–200,000 THB	20	3.4	19	4.1	18	3.8
>200,000 THB	8	1.4	11	2.4	6	1.3
Income change
No change	107	18.5	144	30.9	229	48.7	<.001*
Decreased	473	81.6	313	67.2	208	44.3
Increased	0	0.0	9	1.9	33	7.0
Expense change
No change	405	69.8	388	83.3	368	78.3	<.001*
Decreased	156	26.9	61	13.1	40	8.5
Increased	19	3.3	17	3.6	62	13.2
Cash flow during the COVID-19 pandemic
Neutral cash flow	200	34.5	132	28.3	115	24.5	<.001*
Positive cash flow	204	35.2	280	60.1	331	70.4
Negative cash flow	176	30.3	54	11.6	24	5.1

^aPearson chi-square.

^⁎P < .05.

Dentists’ incomes during the pandemic in 2022 and 2021 were higher than in 2020 (mean rank 935.71, 858.67, and 534.41, respectively, P < .001); the same was true for expenses (mean rank 778.86 vs 708.89, P = .021 in 2022 vs 2020 and 799.71 vs 708.89, P = .001 in 2021 vs 2020).

The percentage of participants whose income was not affected during the pandemic increased from 18.5% in 2020 to 30.9% in 2021 (P < .001) and to 48.7% in 2022 (P < .001). Furthermore, the percentage of participants who maintained a positive cash flow continuously increased from 35.2% in 2020 to 60.1% in 2021 (P < .001) and to 70.4% in 2022 (P = .001) (Figure A).

Fig.

A, Percentage of stressed dentists, the dentists who were working as usual, those whose income were not affected, and those whose positive cash flow were positive in 2020, 2021, and 2022. B, Impact of COVID-19 sequelae on stress. Q1, question 1 (you are worried that you will get infected with COVID-19 from daily activities, such as buying food/goods or traveling to work). Q2, question 2 (you are worried that you will get infected with COVID-19 from performing dental treatment). Q3, question 3 (you feel stressed about your decreased income during the COVID-19 epidemic). Q4, question 4 (you feel stressed about falling stock prices/a bad economy). Q5, question 5 (overall, how stressed you are about the COVID-19 situation). *P < .05. **P < 0.001.

Stress scores and levels

The range of stress scores was 0 to 45, 0 to 56, and 0 to 57 for 2020, 2021, and 2022, respectively. The highest mean stress score was in 2021 (14.39 ± 9.29), followed by 2022 (13.43 ± 10.34) and 2020 (11.29 ± 9.04). The mean stress scores in 2021 and 2022 were significantly higher compared with 2020 (P < .001). However, the mean stress scores in 2021 and 2022 were not different (P = .272).

The percentage of nonstressed participants (hypo- to normal stress level) decreased from 79.5% in 2020 to 68.5% in 2021 (P < .001) and remained stable at 69.6% in 2022 (P = .711), whilst the percentage of stressed participants (mild to severe stress) increased from 20.5% in 2020 to 31.5% in 2021 (P < .001) and remained stable at 30.4% in 2022 (P = .711) (Figure A). The Pearson chi-square test results indicated that the proportions of each stress level (level 0–4) were different between each year (P < .001) (Table 3).

Table 3.

Stress levels.

	2020		2021		2022		P valuea
	n (N = 580)	%	n (N = 466)	%	n (N = 470)	%
Stress levels
0 (score 0–5)	175	30.2	76	16.3	128	25.0	<.001*
1 (score 6–17)	286	49.3	243	52.1	199	48.0
2 (score 18–25)	77	13.3	92	19.7	87	16.9
3 (score 26–29)	17	2.9	26	5.6	20	4.2
4 (score 30–60)	25	4.3	29	6.2	36	7.7
Stressed vs nonstressed
Stressedb	119	20.5	147	31.5	143	30.4	<.001*
Nonstressedc	461	79.5	319	68.5	327	69.6

^aPearson chi-square.

^bStress level 2-4.

^cStress level 0-1.

^⁎P < .05.

Stress levels and correlating factors

The associations between the independent variables and stress levels were simultaneously analysed by multiple logistic regression. This eliminated any possible confounding effect derived from any predictor. Two variables during each pandemic year—income and expenses—and 2 variables in 2022—working status and secondary workplace—were removed from the analysis because they had collinearity with other variables. Seven variables were identified as significant predictors of stress (Table 4).

Table 4.

Multiple logistic regression model.

Variables	2020		2021		2022
	P value	OR (95% CI)	P value	OR (95% CI)	P value	OR (95% CI)
Sexa			.018*	0.50 (0.28–0.89)
Ageb	.001*	0.95 (0.92–0.98)	.001*	0.95 (0.92–0.98)	<.001*	0.93 (0.90–0.96)
Religionc
Christian	.011*	4.52 (1.42–14.37)			.012*	5.17 (1.43–18.63)
Other	.650	0.717 (0.17–3.02)			.189	0.54 (0.22–1.35)
Specialtyd
Operative dentistry	.083	0.24 (0.05–1.20)	.882	0.86 (0.12–6.28)
Endodontist	.004*	0.12 (0.03–0.51)	.007*	0.13 (0.03–0.57)
General practitioner	.088	0.39 (0.14–1.15)	.117	0.40 (0.13–1.26)
Prosthodontist	.004*	0.16 (0.05–0.55)	.594	0.72 (0.22–2.37)
Orthodontist	.006*	0.15 (0.04–0.58)	.012*	0.20 (0.05–0.70)
Oral surgery	.017*	0.24 (0.08–0.78)	.101	0.36 (0.10–1.22)
Paediatric dentist	.048*	0.26 (0.07–10.99)	.022*	0.15 (0.03–0.76)
Others (oral radiologist, oral pathologist, geriatric dentist, etc)	.036*	0.15 (0.02–0.88)	.174	0.25 (0.03–1.85)
Working statuse
Accept only emergency/urgent case			.127	0.53 (0.24–1.20)
Working as usual			.034*	0.41 (0.18–0.94)
Primary working arrangement f
Dental school employee			.728	1.16 (0.51–2.63)
Private hospital employee			.736	1.22 (0.39–3.83)
Private dental clinic owner			.137	1.86 (0.82–4.23)
Private dental clinic employee			.006*	2.83 (1.36–5.91)
Other			.805	1.41 (0.09–21.93)
Cash flow during the COVID-19 pandemicg
Positive	.017*	0.45 (0.23–0.86)			.042*	0.55 (0.30–0.98)
Negative	.051	1.81 (1.00–3.30)			.860	0.38 (0.13–1.15)

^aFemale as a reference.

^b1-year-lower age as a reference.

^cBuddhism as a reference.

^dPeriodontist as a reference.

^eNot working as a reference.

^fPublic hospital employee as a reference.

^gNeutral cash flow as a reference.

^⁎P < .05.

Age, religion, specialty, and cash flow during the pandemic were significant predictors in 2020. During 2020, older age was associated with a lower risk of being stressed (OR = 0.95, P = .001). Being Christian was associated with a higher risk of stress than being Buddhist (OR = 4.52, P = .011). Compared with periodontists, many specialists reported significantly a lower likelihood of being stressed: endodontists (OR = 0.12, P = .004), prosthodontists (OR = 0.16, P = .004), orthodontists (OR = 0.15, P = .006), oral surgeons (OR = 0.24, P = .017), paediatric dentists (OR = 0.26, P = .048), and specialists in less common fields (oral radiologists, oral pathologists, and geriatric dentists) (OR = 0.15, P = .036). Maintaining a positive cash flow during the COVID-19 pandemic was associated with a lower risk of stress compared with a neutral cash flow (OR = 0.45, P = .017).

Although age and specialty remained significant predictors in 2021, religion and cash flow during the COVID-19 pandemic were not. Sex, working status, and primary workplace were found as new predictors. Males reported less stress compared with females (OR = 0.50, P = .018). Older age (OR = 0.95, P = .001) was associated with a lower risk of being stressed. Endodontists (OR = 0.13, P = .007), orthodontists (OR = 0.20, P = .012), and paediatric dentists (OR = 0.15, P = .022) still reported a lower risk of being stressed compared with periodontists, whilst oral surgeons (OR = 0.36, P = .101) and specialists in less common fields (OR = 0.25, P = .174) dropped out in 2021. The participants who were working normally had a lower likelihood of being stressed than those not working (OR = 0.41, P = .034). Private dental clinic employees had a higher likelihood of being stressed than public hospital employees (OR = 2.83, P = .006).

The predictors in 2022 were almost the same as in 2020, except that specialty dropped out. Older age was associated with a lower likelihood of being stressed (OR = 0.93, P < .001). Being Christian was associated with a higher risk of stress than bring Buddhist (OR = 5.17, P = .012). Those maintaining a positive cash flow during the COVID-19 pandemic tended to have a lower likelihood of feeling stressed than those having a neutral cash flow (OR = 0.55, P = .042).

Further analysis using Pearson correlation demonstrated consistent results; age had a significant negative correlation with the stress score in each year (Pearson correlation was −0.213, −0.289, and −0.313 for 2020, 2021, and 2022, respectively, P < .001).

Impact of COVID-19 sequelae on stress

The participants in 2021 had the most significant concern on every question. They worried significantly more than in the other years about getting infected from daily activities (mean scores 5.15 ± 2.65, 6.17 ± 2.49, and 5.46 ± 2.71 in 2020, 2021, and 2022, respectively, P < .001). They were also more worried about the overall COVID-19 situation compared with the other years (mean scores 5.93 ± 2.44, 6.97 ± 2.01, and 5.31 ± 2.48 in 2020, 2021, and 2022, respectively, P < .001). Although their concern about getting infected from work and decreased income was not different from 2020, it was higher than in 2022 (P < .001). The mean scores for worrying about getting infected from work were 6.80 ± 2.58, 7.02 ± 2.47, and 5.12 ± 2.85 in 2020, 2021, and 2022, respectively. The mean scores for worrying about decreased income were 5.43 ± 3.11, 5.84 ± 2.98, and 4.90 ± 3.11 in 2020, 2021, and 2022, respectively. Moreover, they worried more about falling stock prices/a bad economy than the participants in 2020 (P < .001), but not those in 2022 (P = .334) (mean scores 5.08 ± 3.02, 5.84 ± 2.82, and 5.56 ± 3.01 in 2020, 2021, and 2022, respectively) (Figure B).

Discussion

This repeated cross-sectional study compared Thai dentists’ stress during the COVID-19 pandemic in 2020, 2021, and 2022 and identified its associated factors. Over the 3 year assesment period, some of the participants’ sociodemographic, working, and financial status, and stress conditions changed.

The participants gradually resumed work. Thus, their income and overall financial situation continually improved from 2020 to 2022. However, the participants reported the lowest stress level in 2020. In 2021, their stress level increased significantly, then it decreased in 2022 but remained higher than in 2020. This trend coincided with the participants’ reported financial improvement, leaving us questioning the underlying reasons for it.

Different factors caused stress each year. Sex predicted stress in 2021 but not 2020 or 2022. In some COVID-19 pandemic studies on the mental health of dentists and health care workers, women were more stressed than men,^8,9 suggesting that women may be a group in need of attention in this area.

Age was a strong protective factor for all 3 years. Older professionals are more financially secure after years of practice than younger professionals, which may explain this. Furthermore, older participants may have lower baseline stress due to their work and life management experience. However, no study has linked these 2 parameters in dentists during the pandemic.

Religion was also associated with stress levels in 2020 and 2022. Being Christian strongly increased stress risk. Although the link is tenuous, attending a weekly service in a crowded church may cause fear of contracting the disease.

Specialty and stress were related in 2020 and 2021. Although the results were inconsistent across surveys, periodontists reported higher stress levels than other professions, as no other specialties had an OR greater than 1.00. One consideration is that we lacked prepandemic data on the stress levels of each specialty. However, a UK study found no difference in stress levels amongst dental specialties.²¹ Consequently, the difference in stress levels amongst specialties during COVID-19 may be attributed to the different risk level each specialty faced.

Working normally during the pandemic reduced stress in 2021 participants, according to our study. This group may have been less stressed because they could generate income whilst those not working could not, or they may have been unconcerned about the risk of infection and continued practicing. However, working status did not predict stress in 2020 or 2022. This group may have had too few participants in 2020 to determine its significance. Furthermore, since the reference group in 2022 had only one participant, this variable had to be removed from the equation to calculate.

Only in 2021 did private dental clinic employees experience greater levels of stress than public hospital employees. This may be because public hospital participants were paid by constant salary which was unaffected by fewer clinical treatments performed during the pandemic, whereas private dental clinic employees’ incomes were based on numbers of patient treatments.

Although many studies investigated various factors on dentists’ mental health during the COVID-19 pandemic, this is the first to examine the financial association. The participants’ cash flow during the pandemic significantly impacted their stress levels in 2020 and 2022. During these years, the participants with a positive cash flow were less stressed, whilst a negative cash flow was associated with higher stress in 2020. Several psychological studies linked low income or financial strain to mental health disorders.22, 23, 24, 25

Apart from the highest stress level in 2021, the scores from the 5 numeric rating scale questions revealed the same trend where COVID-19 sequelae in 2021 had the highest impact on stress.

Over the 3 years, 2021 participants reported the greatest worry score about getting infected from daily activities and the overall COVID-19 situation. There were many possible factors related to this phenomenon. In 2021, there were many virulent COVID-19 strains, including the Alpha variant and Delta variant, which was the dominant variant that was highly infectious with a high fatality rate at the time of the 2021 survey.^15,26,27 Additionally, Thailand's vaccination program had just begun. Therefore, most participants were still very susceptible to infection.

In 2021, the participants remained much worried about getting infected from performing dental treatment. This might be because they and their patients still lacked immunisation, and although approximately half of the participants had returned to work, they might be unsure whether the new infection control protocols would protect them from the more virulent COVID-19 strains. In 2022, their worry score was much lower, even lower than in 2020. This could possibly be because by then the vaccination program had immunised 75% of Thais and the dominant viral strain had become less fatal.²⁸ In addition, since no dentist had been infected during treatment, they may have trusted the new virus infection control protocols.

Although 2021 participants reported a higher income, they were worried about their decreased income, similar to 2020 participants. The worry related to income finally decreased in 2022. This may be because almost all participants in 2022 worked normally, whilst nearly half in 2021 accepted only emergency and urgent cases. Thus, almost half of participants reached their previous income level in 2022, compared to only one-third in 2021. The higher percentage of 2022 participants with a positive cash flow may also indicate financial improvement, making them less worried than in 2021.

Even with improved financial situations in 2021 and 2022 compared to 2020, participants expressed greater concerns about falling stock prices and a weak economy. This may add an explanation for why stress did not decrease in 2021 as expected.

In this situation, dentists need affordable and accessible stress-reduction tools. Using technology to introduce internet-based cognitive behavioural therapy (I-CBT) may be one possible choice. Platforms like Moodle can deliver I-CBT, which can address cognitive biases, teach relaxation techniques, and combat maladaptive coping behaviours.^29,30 The profession's demands may make I-CBT a proactive way to improve Thai dentists’ mental health.

This study received more responses than the minimum sample size, resulting in a 98.1% power to accurately predict the proportion of stressed dentists. Due to the large sample size, multiple logistic regression was used to evaluate variables simultaneously and eliminate any variable's confounding effect. These factors strengthened the study.

Whilst the study had its strengths, there were also some methodological flaws. The study's convenience sampling method may have favoured dentists who were predisposed to answering the questionnaire and excluded dentists experiencing higher levels of stress.²⁴ Furthermore, the Thai population has one of the highest rates of social media use in the world, and the number of returned questionnaires was high, but using social media to distribute the questionnaire may have skewed the sample toward younger dentists. Self-reported questionnaires may have caused memory and social-desirability biases. Participants may have misinterpreted questions or made mistakes. Finally, because stress was compared across years using different participant groups, this repeated cross-sectional study must be interpreted carefully.

Conclusions

The stress levels of Thai dentists due to the COVID-19 pandemic increased from 2020 to 2021 and then plateaued during 2022. In every year, younger participants were more stressed than the older folk. In 2 out of 3 years, specialty and finances were linked to stress. These results suggest that dentists should be financially literate. Moreover, I-CBT may be a useful stress-reduction technique in this situation. It was unknown why age and religion influenced stress levels. Future research should investigate these factors.

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. This study was funded by a Faculty Research Grant, Faculty of Dentistry, Chulalongkorn University (grant number: DRF64036). The funder had no role in the study design, data collection, data analysis, data interpretation, writing of the report, or decision to submit the paper for publication.