To our knowledge, this is the first study to investigate the association between dental anxiety and PTEs while considering mental health symptoms and self-reported oral health.
The present study investigated dental anxiety in the adult population (> 40 years old) in Tromsø and in accordance with the stated objectives, this population expressed a lower prevalence of dental anxiety than expected [9, 11, 13, 16, 64]; however, this study confirmed previously reported associations between dental anxiety and sex, age, dental attendance, previously traumatic or painful dental treatments and oral health [13, 16, 20, 65].
This study also found that the following potentially traumatic events outside the dental setting had a significant impact on our hierarchical regression model at the stage they were entered: sexual abuse, painful or scary medical treatment at the hospital and childhood neglect. Of these, only sexual abuse remained a significant predictor after controlling for current mental health symptoms. Furthermore, the mediation analysis provided evidence that current mental health symptoms seem to mediate the effect of traumatic or painful medical treatment in hospital, sexual abuse and neglect in childhood on dental anxiety. However, sexual abuse was only partially mediated.
The results of this study indicate that reporting sexual abuse has a direct significant influence on dental anxiety in the general population. In other words, the experience of sexual abuse appears to impact dental anxiety in individuals irrespective of whether the same individuals are experiencing generalised mental health problems (e.g. depression, anxiety). This could point to sexual abuse experiences being somehow directly conditional on dental anxiety , but also clarifies the lack of conscious awareness of the link between sexual abuse and dental anxiety, which might be evident in some survivors of sexual abuse . Evidence shows that many aspects of dental treatment can trigger memories and flashbacks from sexual abuse within the concept of trauma coupling [46, 54, 66]. Crossing lines of intimacy in the dental setting can be difficult in itself, but the oral cavity may have been violated directly, which could make the dental setting even more challenging [45, 67]. Dental treatment requires touching the face and head of the patient, inserting fingers in the oral cavity, using water spray and rubber gloves and relying on the patient’s ability to keep their mouth open during certain procedures. Furthermore, being in a reclined position with dental health professionals leaning over and intruding into one’s personal space can trigger feelings associated with losing control and being trapped . Remaining motionless, not having the ability to speak and not seeing what the dentist is doing also may echo feelings of being violated all over again [55, 66]. The dental personnel’s reassurances can also trigger memories since perpetrators often do this as well as a means of justifying their actions or controlling the situation. This might include telling victims to keep calm, that it will not hurt and that it will be over soon . Survivors of sexual abuse have reported persistent problems with dental treatment despite the processing and mental resolving of the abuse in other aspects of their lives , which could indicate that exposure to the dental setting, with all its triggers, is especially important for these individuals.
The regression analysis underlines the importance of traumatic dental treatment, oral health and the avoidance of dental treatment as predictors of dental anxiety. However, it is worth noting that most of the variance in dental anxiety is unaccounted for in this model, which points to the fact that there is more to explaining variance in dental anxiety than the factors included in the current model. One aspect that was not controlled for was personality factors, such as neuroticism, which are considered an important predictor of health in general , and dental anxiety specifically [12, 63]. Another factor that was not considered was oral health-related quality of life, which evidence shows is often impaired in dentally anxious individuals . Oral health affected by dental anxiety and subsequent avoidance behaviour may affect the oral health-related quality of life and lead to social isolation and the presentation of symptoms related to depression and general anxiety [71, 72]. Dental anxiety has a multifactorial aetiology; hence, effect sizes for the single variables are not expected to be high. Identifying these variables is important, but they must be considered as a part of a set of variables to be able to understand the clinical variations in the population.
The avoidance of dental treatment is much more prevalent among anxious individuals compared to the rest of the population. Still, 60% of the dentally anxious participants reported going regularly to the dentist, and 89.8% of all the participants in this study reported a regular attendance pattern. This is higher than the numbers reported in a population study including adults from the whole of Troms County, where 77.7% of the entire population under study reported similar regular attendance . The private sector provides the majority of dental care for the adult population in Norway without any public involvement concerning the geographical distribution of dental clinics or fees for dental services. That could be problematic with regard to the provision of equal health care, making accessibility and personal economy more predictive of regular dental attendance than other factors . Thus, the adult population in Tromsø, a city with a high density of private clinics, will perhaps have better access to dental health care compared to more rural areas. Also, individuals with a dental phobia who chose not to participate in this study would probably be more inclined to use avoidance as a strategy than the phobic participants that participated in this study, which would influence the reported attendance pattern. Note that the reporting of regular dental treatment includes the option “less than once every two years”, an alternative that could be considered to be more irregular.
There is some controversy in terms of performing mediation analyses on cross-sectional data since the order of occurrence of reported measures is unknown in an individual’s life. The HSCL-10 measures current symptoms (the last two weeks), and it is reasonable to assume that traumatic life events most likely happened sometime previous to the last two weeks in these types of studies. Similarly, the MDAS is also a current measure, which makes it impossible to pinpoint the onset of dental anxiety in the past. Even though the order of events can be stipulated or hypothesised, causal effects cannot be ascertained, and the direction of correlation in the mediation analyses is probably, to some extent, bidirectional. Current mental health symptoms might affect reported traumatic events , and high dental anxiety could influence current mental health symptoms. Nevertheless, there is a well-documented link between traumatic life events and mental health. Having experienced trauma increases the likelihood of developing mental health disorders, like PTSD, depression and anxiety [76–79]. There is also convincing evidence concerning the higher prevalence of psychological disorders among highly dentally anxious individuals  and the role of psychological disorders in the maintenance of dental anxiety. It could be argued that some traumatic life events might affect dental anxiety as a result of causing increased vulnerability in an individual. That is, the psychological consequences of traumatic experiences might increase susceptibility to dental anxiety and poorer oral health.
There was a low prevalence of highly anxious participants in this study compared to previous investigations, as only 2.9% of the participants scored over the cut-off value of 19 for high dental anxiety. This could be interpreted as a result of a continuous decline in dental anxiety in the adult population  or reflect differences in the measures used to classify high dental anxiety. Still, the possibility of issues with the representativeness of individuals with high dental anxiety in the study population cannot be ruled out, especially considering that some of the participants were to undergo a thorough clinical dental examination. This could, to some extent, hinder recruitment among highly dentally anxious individuals due to the avoidance behaviour that characterises the phobic disorder . This is the obvious pitfall of all population studies in the field. However, the questionnaire data used were collected independently of the dental examination, so the dentally anxious could participate in the study while declining the oral examination. Also, if considering the possible bias of representativeness, it can be inferred that the associations in all the bivariate analyses are supported by the existing literature, and including a larger portion of dentally anxious individuals would probably enhance rather than lower the effect sizes of the correlations observed.
Self-reported measures without any clinical markers are problematic and can give rise to bias. Recall bias is often an issue in epidemiological research, and the reporting of traumatic life events can be over- or underreported due to such bias. This can affect the association between reported traumatic events and health-related outcomes, here dental anxiety and current mental health symptoms. Studies have shown that the effect of adverse childhood experiences is present in adult health, despite people not recalling or failing to report such events [75, 81]. Adverse or traumatic life events can be useful and important to individuals when they are trying to make sense of their health problems [81, 82]. Hence, traumatic events could be more relevant to individuals that struggle with mental health problems, and traumatic dental treatment experiences could be more accessible to individuals with dental anxiety. People that are in good health without current problems tend to “forgive and forget” adverse events in their past , adding to the risk of underestimating the associations of interest.