Dental anxiety has been a topic of investigation for over two centuries, with its historical roots traced back to the late 1800s and early 1900s (Yeung, 2023). The terms ‘dental fear,’ ‘dental anxiety,’ and ‘dental phobia’ are often used interchangeably, but they refer to distinct mental states with different clinical features. Fear is characterized as a response to immediately threats, triggering a high state of arousal and activating the sympathetic nervous system, which prepares individuals for a “flight-or-fight” response. Meanwhile, anxiety involves apprehension about anticipated future threats, with lower arousal compared to fear. Individual experiencing anxiety may feel tense and restless. Specific phobia, categorized as an anxiety disorder in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) (American Psychiatric Association, 2013) and the International Classification of Disease, eleventh revision (ICD-11) (World Health Organization, 2019), is characterized by excessive and disruptive fear of a particular object or situation. The exaggerated fear experienced in dental phobia is irrational and disproportionate to the actual danger posed. Individuals with phobias may acknowledge the excessive and unrealistic nature of their fear but struggle to control their preoccupation with the feared object or situation. Avoidance of distressing situations is common among people with phobias and can significantly impair their daily functioning (Kring et al., 2007; American Psychiatric Association, 2013; Kring and Johnson, 2018; World Health Organization, 2019).

Dental anxiety and dental phobia are not classified in DSM-5 or ICD-11. Some researchers have suggested that dental phobia can be considered as an example of specific phobia, but it is unclear whether it should be grouped under the blood–injection–injury (BII) subtype (300.29) in DSM-5 or as an independent subtype (Kılıç et al., 2014; Van Houtem et al., 2014). The prevalence of dental anxiety has been investigated in various populations over the past few decades and has been shown to be common and persistent in general population. A recent meta-analysis found that the prevalence of dental anxiety among preschoolers, schoolchildren and adolescents was 36.5, 25.8, and 13.3%, respectively, (Grisolia et al., 2021). Another recent meta-analysis reported a global prevalence of dental anxiety among adults to be 15.3% (Silveira et al., 2021), indicating that dental anxiety is high across different age groups worldwide.

Dental fear is a complex and multifactorial phenomenon that can set the stage for the development of dental anxiety or dental phobia. Several risk factors have been found to increase the likelihood of developing dental anxiety or dental phobia, some of which are modifiable or controllable while others are not. Modifiable factors include the influence of family members, friends and media (Wong et al., 2022), negative attitude from dental practitioners, perceptions of dentists’ behavior, communication style and competence (Corah et al., 1985; Abrahamsson et al., 2002), feelings of a lack of control and unpredictability (Rouse and Hamilton, 1990), fear of dental surgery (Oosterink et al., 2008), and anxiety-provoking stimuli such as the sound of dental drills, the act of injections, the sight of needles, and the smells of the clinic (Moore et al., 1993; Oosterink et al., 2008; Wong et al., 2022). Non-modifiable factors include a history of psychological disorders (Locker et al., 2001), previous traumatic dental experiences (Murad et al., 2020), personality traits such as introversion and neuroticism (Schuurs et al., 1988; Halonen et al., 2012), a lower pain threshold, and a higher sensitivity to pain (Klages et al., 2004). Other non-modifiable factors such as genetics, gender, and age also contribute to dental anxiety (Ray et al., 2010; Appukuttan et al., 2015; Randall et al., 2017; Yildirim et al., 2017), though findings are not necessarily consistent across studies (Fayad et al., 2017). Dental anxiety is a complex issue, and the relationship between one factor may be influenced by other factors. Possible reasons for discrepancies in findings include differences in sampling methods, the recruitment of clinical samples, and the use of different dental anxiety measurements. Further research is needed to better understand the relationship between dental anxiety and various factors.

Adverse childhood experiences (ACEs) refer to traumatic events that occur before the age of 18. They include a broad range of stressful or disruptive events such as (i) childhood maltreatment (which can take various forms of neglect and abuse, including mental, physical or sexual), (ii) family dysfunction (such as living with household members with alcohol or drug addiction, mental illness, suicidal tendencies, a history of incarceration, experience of parental death, separation or divorce, and witnessing domestic violence), and (iii) violence outside the home (including being bullied, witnessing community violence, and exposure to collective violence) (World Health Organization, 2020). It is estimated that ACEs have a high global prevalence ranging from 41 to 97% (Carlson et al., 2020), which is a significant concern due to their long-term detrimental impact on individuals’ health and well-being. Research has shown significant negative effects of ACEs on both physical and mental health, as well as behavioral problems and social issues (Bethell et al., 2014; Kalmakis and Chandler, 2015; Hughes et al., 2017). Critically, ACEs have also been found to play a significant role in the development of psychiatric conditions such as schizophrenia (Baldini et al., 2023) and bipolar disorder (Miola et al., 2023). Studies have revealed that early-life traumas can disrupt neurodevelopment, contributing to the pathogenesis of these severe mental illnesses. Furthermore, the relationship between ACEs and suicidal behaviors has been established, with individuals exposed to ACEs demonstrating a higher risk of suicidal ideation, self-harm, and suicide attempts (Dube et al., 2001). This highlights the importance of understanding the complex interplay between ACEs and severe psychiatric conditions, and the need for targeted interventions to address these issues.

ACEs have been found to negatively impact individuals’ physical health. Previous studies have shown that individuals with ACEs have a higher risk of developing chronic diseases such as heart disease, diabetes, cancer, and obesity (Monnat and Chandler, 2015; Wiss and Brewerton, 2020). Furthermore, research suggests that ACEs can weaken individuals’ immune systems, making them more susceptible to diseases (John-Henderson et al., 2020). Studies have also shown that individuals with a higher ACE score have a higher risk of sleep disturbances (Kajeepeta et al., 2015) and early death (Brown et al., 2009). Research has also shown that individuals with ACEs are at a higher risk of developing mental health issues later in life, such as depression, anxiety and other mood disorders, post-traumatic stress disorder (PTSD), or other trauma-related mental health issues (Kalmakis and Chandler, 2015; Hughes et al., 2017). Furthermore, ACEs have been associated with the development of undesirable behavioral and social issues, such as drug or substance addiction, smoking, criminal behavior, unprotected sexual activities, attempting suicide, having interpersonal difficulties, and struggling to build and maintain healthy relationships (Dube et al., 2001; Poole et al., 2018; Petruccelli et al., 2019).

Although many studies have investigated the risk factors of dental anxiety, most have been limited to considering only dental-related stimuli and experiences, overlooking factors beyond the dental field. Research suggests that non-dental traumatic experience may also contribute to the development of dental anxiety (De Jongh et al., 2006). To the best of our knowledge, no study has yet been conducted to investigate the impact of ACEs (i.e., experiences before the age of 18 years) on dental anxiety. The aim of this study was to explore the association between dental anxiety and ACEs in a sample of Chinese adults in Hong Kong. It was hypothesized that ACEs would be positively associated with dental anxiety. The findings of this study might contribute to the understanding of ACEs survivors and inform clinicians whether it is necessary to inquire about ACE history before initiating dental treatment.

The objective of the present study was to investigate the relationship between adverse childhood experiences (ACEs), including both cumulative ACEs and individual types of ACE components, and dental anxiety in adulthood. Building upon prior research (Reiser et al., 2014), we hypothesized that there would be significant positive associations between ACEs and dental anxiety. The findings of this study support our hypothesis, indicating that exposure to ACEs is indeed associated with increased dental anxiety. Specifically, when ACEs were assessed cumulatively, participants who reported a higher number of ACEs exhibited elevated dental anxiety scores, as measured by MDAS and DFS. Furthermore, our results revealed a significant association between the number of ACEs and the risk of developing high dental anxiety. In addition to the cumulative number of ACEs, our findings also suggest that specific types of ACE components, such as sexual abuse, physical neglect, collective violence, and living with alcohol and/or drug abuse, were independently associated with high level of dental anxiety.

Although the association between ACEs and negative health outcomes has been extensively explored (Hughes et al., 2017; Petruccelli et al., 2019), no previous study has specifically investigated the impact of ACEs on dental anxiety. Therefore, the present study represents a novel contribution by providing a comprehensive examination of both the cumulative and independent roles of ACEs in relation to dental anxiety. Our findings revealed that a significant proportion (84%) of the participants in this study reported exposure to at least one ACE. This prevalence is consistent with the results of a previous study that examined the patterns of ACE exposure in young adults in Hong Kong using the ACE-IQ questionnaire (74%) (Ho et al., 2019). Furthermore, our findings align with international norms, as a recent systematic review demonstrated that 75% of participants across 61 studies had experienced ACEs (Pace et al., 2022).

The results of the present study provide evidence that dental anxiety is significantly associated with the number of ACEs, which is consistent with findings from previous studies examining mental health outcomes. Several similar studies that employed the ACE-IQ questionnaire to investigate the impact of childhood adversity on health outcomes have reported significant associations between ACE exposure (both cumulative and individual ACEs) and increased odds of anxiety disorders (Subramaniam et al., 2020), psychological distress (Agbaje et al., 2021), and health-related quality of life (Cohrdes and Mauz, 2020). Besides, findings from a study that utilized a different form of ACE measurement also suggested a significant association between ACEs and health anxiety (Reiser et al., 2014).

Furthermore, specific components of ACEs, such as physical neglect and emotional neglect, were identified in this study as factors that increase the likelihood of high dental anxiety. The association between neglect as a form of childhood maltreatment and high dental anxiety can be explained by the development of early maladaptive schemas. Early maladaptive schemas refer to emotional and cognitive patterns that form early in life and continue to be elaborated and repeated throughout life, often to a dysfunctional extent (Young, 1990). A comprehensive review of early maladaptive schemas can be found in (Young et al., 2006). Individuals who have experienced neglect as a form of childhood maltreatment may develop characterological problems and personality disorders (Young, 1999). Consequently, they may exhibit negative cognitive styles or perceptual disturbances, such as being overly vigilant and suspicious of others and having a sense of shame (Rose and Abramson, 1992; Ered and Ellman, 2019; Loewy et al., 2019). These factors can in turn influence their behaviors, leading to social withdrawal and distancing from others (Alink et al., 2012; Maier et al., 2020). These behaviors have been well-established as factors associated with dental anxiety (Moore et al., 1993; De Jongh et al., 2006).

In addition, this study found that sexual abuse was associated with an increased likelihood of high dental anxiety. This can be explained by the perception individuals may have of dentists and dental situations following exposure to ACEs. Sensory stimuli associated with dental treatments, such as sight of hands, sounds of breathing from the dentist, taste and smell of gloves, and sensations of dental instruments and fingers inside the mouth, might trigger memories associated with their experiences of sexual abuse or even serve as a repetition of the abuse itself (Leeners et al., 2007; Fredriksen et al., 2020). Besides, victims of sexual abuse often exhibit poor self-image, fear of intimacy, and difficulties in forming trusting relationships (Davis and Petretic-Jackson, 2000), which can contribute to feelings of powerlessness and a lack of control (Chouliara et al., 2014). These factors have been shown to be associated with dental anxiety (Willumsen, 2004; Scandurra et al., 2021).

The measurement of ACEs and how they are measured is crucial in addressing research questions. A recent meta-analysis by Hughes et al. (2017), which examined 37 studies investigating the relationship between ACEs and health outcomes, found a diverse variation in the items used to classify ACEs across the studies. Some studies measured childhood adversity through aspects of “family dysfunction” and “childhood maltreatment experiences,” while others also included the aspect of “violence exposure.” The inconsistency in measuring childhood adversity may lead to inconsistent and inconclusive results, highlighting the importance of standardizing the measurement approach in ACE research.

The measurement of ACEs often involves a cumulative risk approach, which uses a sum score to assess an individual’s exposure to adverse experiences (Hughes et al., 2017; Petruccelli et al., 2019). This approach assumes that the accumulation of risk factors negatively impacts development and increases the likelihood of negative health outcomes. The more risk factors an individual is exposed to, the higher the prevalence of clinical problems or the worse the outcome (Sameroff, 2000; Appleyard et al., 2005; Evans et al., 2013). While this cumulative approach provides a general picture of the impact of ACEs and their potential to predict negative outcomes, it may not be adequate or clinically meaningful in practice when individualized intervention is desired. This is because the distinctive nature and effect of each individual’s childhood adversity may be overlooked. Hence, while the use of a cumulative ACE score can identify high-risk individuals and facilitate early intervention strategies, it may not provide tailored intervention for every individual. It is important to consider alternative approaches that capture the unique experiences and effects of individual ACEs. For example, our findings found that dental anxiety was associated with only sexual abuse, but not emotional abuse, and physical abuse.

The present study has several potential limitations that should be acknowledged. Firstly, there is the possibility of response bias, as participants may have exaggerated or underreported their self-reported measures of ACEs and dental anxiety. This could occur when respondents overstated their negative feelings and experiences, influencing their responses. Conversely, respondents might have difficulty recalling past events or might hesitate to disclose their experiences and behaviors, leading to misclassification or misidentification of exposure to the outcome measures. This limitation could potentially result in an over- or underestimation of the strength of the relationships between ACEs and dental anxiety. Secondly, the sample in the present study was limited to university students and staff. As a result, caution should be exercised when generalizing the findings to the general population, as the external validity of the results might be limited.

From another perspective, the prevention of ACEs is a critical area of focus for researchers, policymakers, and practitioners. There are several potential future directions that could be explored in order to advance the field and contribute to the development of more effective prevention strategies. One important aspect of ACE prevention is early intervention and support for families and children at risk. This can be achieved through the provision of resources and education for new parents, offering parenting classes and support groups, and implementing home visitation programs for families in high-risk situations. A comprehensive approach to prevention must also include expanding access to mental health services for children and families. This may involve increasing funding for mental health care, training more mental health professionals, and integrating mental health services into schools and community centers. By preventing the development of ACEs, it is hoped that young people in future generations will generally have a lower level of dental anxiety, so that they can arrange prompt dental visits to maintain their oral health and oral health-related quality of life.

In conclusion, our study found a positive association between ACEs and dental anxiety, with certain types of individual ACEs showing increased odds of high dental anxiety. The results from MDAS and DFS were not consistent, indicating that contextual differences may exist between these measurement tools of dental anxiety. Understanding the relationship between ACEs and dental anxiety is important not only for patients and dental practitioners in terms of screening target patients, developing treatment plans, and selecting appropriate interventions tailored to individual needs, but also for society in providing services adapted to the local context. Dental practitioners should inquire about and understand a patient’s ACE history as part of their background information and show empathy towards ACE survivors with interactions deemed comfortable by them.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

The studies involving humans were approved by Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

NW: Conceptualization, Data curation, Formal analysis, Investigation, Writing – original draft, Writing – review & editing. AY: Data curation, Writing – original draft, Writing – review & editing. CM: Supervision, Writing – original draft, Writing – review & editing. YL: Supervision, Writing – original draft, Writing – review & editing.