Factors for determining dental anxiety in preschool children with severe dental caries

: The aim of this study was to assess the clinical and socioeconomic indicators associated with dental anxiety in preschool children with severe dental caries. A total of 100 children between 3 and 5 years of age were selected during a dental screening procedure. The selection criteria were having at least one tooth with dental caries and a visible pulpal involvement, ulceration, fistula, and abscess (PUFA) index of ≥1 in primary teeth. Before the clinical examination or any treatment procedure was performed, we evaluated the children’s dental anxiety using the Facial Image Scale (FIS). Parents completed a questionnaire on socioeconomic conditions, which included the family structure, number of siblings, parental level of education, and family income. A dentist blinded to FIS and socioeconomic data performed the clinical examination. Poisson regressions associate clinical and socioeconomic conditions with the outcome. Most of the children (53%) experienced extensive dental caries (dmf-t ≥ 6), and all children had severe caries lesions, with a PUFA index of ≥1 in 41% and that of ≥2 in 59%. The multivariate adjusted model showed that older children (4–5-year old) experienced lower dental anxiety levels compared with younger children (3-year old) (RR = 0.35; 95%CI: 0.17–0.72 and RR = 0.18; 95%CI: 0.04–0.76, respectively), and children with three or more siblings were associated with higher levels of dental anxiety (RR = 2.27; 95%CI: 1.06–4.87). Older age is associated with low dental anxiety, and more number of siblings is associated with high dental anxiety in preschool children, whereas the severity or extent of dental caries is not associated with dental anxiety.


Introduction
Dental anxiety is a common problem that pediatric dental practitioners encounter daily. It can affect patient management and dental attendance 1 and can persist even in adulthood, leading to dental avoidance. 2 There is currently no singular explanation for the development of dental anxiety in children, and its etiology is still not entirely understood. The nature of this particular kind of anxiety could be related to diverse factors such as the age of children, their sociocultural background, or their Declaration of Interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript.
parents' dental experiences. 3,4 However, there is some support for the argument that the modeling pathway could be important in the development of children's dental anxiety. 5,6 It has been suggested that children who have had previous dental experiences could have higher levels of dental anxiety. 7,8 However, the evidence remains insufficient. A recent study observed that dental anxiety in children is more directly related to dental caries, 9 but there are no studies that investigate the association between the severity of caries and high levels of dental anxiety. To date, the association between anxiety and dental caries has not been tested in preschool children with severe dental caries.
Moreover, the abovementioned studies mostly concentrate on children aged ≥5 years, with only one study evaluating dental anxiety in children aged <5 years. 10 Most of these studies have been conducted in developed countries. 7,8 However, there have been a few studies in developing countries, 9,11 which could affect the results owing to the cultural differences between developing and developed countries. To the best of our knowledge, there are no studies assessing indicators associated with dental anxiety in preschool children with dental caries using self-reports.
Thus, given the lacking and conflicting information regarding the nature of children's dental anxiety, the purpose of this study was to assess the clinical and socioeconomic indicators associated with dental anxiety in preschool children with severe dental caries.

Methodology
This study was approved by the Human Research Ethics Committee of the Dental School of the University of São Paulo (500.61) in compliance with Brazilian National Health Council Resolution 466/12. All parents received information regarding the objectives of the study and provided written informed consent regarding their child's participation.

Study population and data collection
This study is part of a randomized clinical trial (ClinicalTrials.gov Identifier NCT01858298) that assessed OHRQoL in preschool children who were later subjected to two types of treatments for severe dental caries: pulpectomy and tooth extraction (Abanto et al., unpublished results). Thus, the study included children aged 3-5 years because at this age teeth are younger and have not yet begun the root resorption process. Here all anxiety assessments were performed at baseline, i.e., before the children were subjected to any clinical examination or treatment. For the randomized clinical trial, sample size was calculated to give a standard error of 5% with a 95% confidence interval (CI). The prevalence of dental anxiety in children aged 4-5 years was set at 28.9% 11 , and the minimum sample size was estimated to be 100 children. Therefore, the number of children included in this study was 100.
The sample comprised 100 children who sought dental treatment in the Pediatric Dentistry Department of the Dental School at the University of São Paulo (USP), Brazil. The children were aged 3-5 years and selected during a dental screening procedure at USP. The selection criteria were having at least one tooth with dental caries and a PUFA index of ≥1 in primary teeth. Children with systemic and/or neurological diseases or who had undergone dental treatment in the last 3 months as well as siblings were excluded.
On the day of their first dental appointment, the children first underwent a dental anxiety assessment. A previously trained interviewer (blinded to any oral data) assessed the children's dental anxiety before the clinical intervention/examination. The interviewer also gathered data on the socioeconomic conditions of the family, such as family structure (if the children were living with both parents or not), number of siblings (none, one, two, or ≥three), parental level of education (≤8 years or >8 years), and family income. Family income was categorized using the Brazilian minimum wage, which corresponds to approximately 340 US dollars per month. Information concerning the child's previous visits to the dentist was also collected.
After the interview, a trained and calibrated examiner conducted the children's oral examinations. Dental caries experience was assessed in primary teeth, and we used the dmf-t criteria, classifying teeth as decayed, missing, or filled. 12 We used the PUFA index for classification of disease severity. 13 The examiner had been previously trained through a process conducted in two stages. The first stage comprised theoretical discussion with an expert in pediatric dentistry, and in the second stage, the examiner underwent two sessions of calibration, during which the examiner assessed 20 children who received dental treatment at the university clinic. The examinations of these 20 children were repeated at an interval of 1 week between the sessions. These examinations were used to obtain intraexaminer reliability kappa values, and the children who participated in the training process did not take part in the study. Cohen's kappa intraexaminer agreement values were 0.98 for dmf-t and 1.0 for PUFA.

Children's dental anxiety
The Facial Image Scale (FIS) 14 was used to evaluate the children's dental anxiety according to self-reports. This scale comprises a row of five faces, ranging from "very happy" to "very unhappy." All the faces are scored by giving a value of 1 to the happiest face and 5 to the saddest face. The interviewer asked each child to point at the face they felt most like at that moment. The scores were recorded and later categorized for analysis: 0 = no anxiety (FIS score 1), 1 = low or moderate anxiety (FIS scores 2 and 3), and 2 = high or very high anxiety (FIS scores 4 and 5). All interviews were conducted outside the dental setting (before the child was taken to the dental office) 14 .

Children's oral examination
The oral examinations were performed in a dental unit using an operating light, plane dental mirrors, ballended WHO probes, and a three-in-one syringe for drying the teeth. The total dmf-t 12 score was then calculated, and the patients were then categorized according to caries experience based on the previously proposed scores 15,16,17,18 : dmf-t = 1-5 (low) and dmf-t ≥ 6 (high).
The PUFA index 13 was used to assess the presence of oral conditions resulting from untreated dental caries. Like the dmf-t index, each tooth was given a visible pulpal involvement, ulceration, fistula, and abscess (PUFA) index, according to caries severity. 13 The total PUFA index per patient was then calculated in the similar cumulative way as the dmf-t index and represented the number of teeth that meet the PUFA diagnostic criteria. To simplify the statistical analyses, caries severity for each child was then categorized according to the child's total PUFA index: 1 (total PUFA index = 1), 2 (total PUFA index = 2), and 3 (total PUFA index ≥ 3).

Data analysis
Data analyses were performed using IBM SPSS software, version 22 (IBM Corp., Armonk, NY, USA). Poisson regression with robust variance was performed to associate dental anxiety scores with dental caries experience, PUFA, and socioeconomic conditions. The extent of caries experience and PUFA were considered to be continuous variables in the statistical analysis. Univariate Poisson regression analysis was performed to select variables with a p-value of ≤0.20 to enter the model. Then, explanatory variables selected were tested in the multivariate adjusted model and retained only if they had a p-value of ≤0.05. In this analysis, the outcome was employed as a count outcome, and rate ratios (RRs) and 95% CIs were calculated. Caries experience and PUFA index variables were retained in the final model as control variables.

Results
Of the 107 eligible participants, 100 provided informed consent (positive RR = 93.5%). Table 1 shows the socioeconomic and clinical conditions of the sample. Overall, 53% of the children had high dental caries experience (dmf-t ≥ 6) and 48% had a PUFA index score of 2. A total of 39% of the children had little or some anxiety (FIS score 2 or 3). Most of the preschool children lived with both parents (89%) and 49% had no siblings. A majority of the children had no previous visits to the dentist (82%) ( Table 1). Table 2 shows the univariate unadjusted analysis of clinical and socioeconomic conditions variables associated with dental anxiety scores. Dental anxiety scores were significantly associated with the child's age (p < 0.05). The multivariate adjusted model ( Table 2) showed that older children (aged 4-5 years) experienced lower dental anxiety levels than younger children (aged 3 years) (RR = 0.35; 95%CI: 0.17-0.72 and RR = 0.18; 95%CI: 0.04-0.76, respectively). Also, children from larger families, with three or more siblings, had higher dental anxiety levels (RR = 2.27; 95%CI: 1.06-4.87). Conversely, children who had previous visits to the dentist had lower dental anxiety levels (RR = 0.38; 95%CI: 0.15-0.97).

Discussion
This study assessed the socioeconomic and clinical indicators associated with dental anxiety in preschool children with severe dental caries. To the best of our knowledge, this is the first study to assess anxiety in preschool children with dental caries aged 3-5 years using self-reports.
It has been affirmed that dental anxiety could be considered a risk factor for dental caries experience; 8 however, in our study, neither the extent of caries experience nor dental caries severity (based on PUFA index scores) in young children was associated with dental anxiety. This is in accordance with a previous cross-sectional study that found no association between dental caries and dental anxiety in older children. 19 This suggests that irrespective of whether children have more caries lesions or deeper lesions, caries experience and severity does not play a substantial role in the anxiety level of children. However, the association between lower caries severity and dental anxiety should be further investigated. Thus, future studies involving children with lower degrees of caries severity should be conducted to assess whether there is any association with dental anxiety.
Other more general factors could better explain the children's anxiety levels before dental treatment. It has been reported that dental anxiety could decrease with age. 4,20,21 Likewise, in this study, we found that 4-5-year olds experienced less dental anxiety than the 3-year olds. This could be owing to the development of cognitive abilities as well as the manner in which children learn to deal with anxious situations. 22 Older children have greater cognitive ability, a better understanding of their surroundings, and a better perception of frightful situations; hence, they are less susceptible to dental anxiety. 22 Moreover, older preschool children are better at assimilating the explanations given by their (nonanxious) parents and/or dentists, thereby reducing their dental anxiety. We observed that preschool children with three or more siblings have higher dental anxiety levels.
One explanation for this could be that children from larger families could be directly or indirectly exposed to information about their siblings' dental treatments or they could observe their siblings displaying anxious behaviors during dental treatments. Thus, it could be expected that children with more siblings may be susceptible to negative thoughts, which might have an impact on their dental anxiety. 5,23 One study showed that in children with siblings, the first-born child was at increased risk of developing negative behavior and dental anxiety. 24 We did not have birth-order information for the children recruited children in this study. However, the role of the birth order could be assessed as a possible factor of behavior during dental treatment in further studies. Because children normally spend a lot of their time with their siblings, it is important to further investigate exactly how siblings can influence young patients' dental anxiety levels.
Previous studies have shown that high levels of dental anxiety in children are strongly associated with traumatic dental settings 8 and previous negative dental experiences. 20 Therefore, we included previous visits to the dentist as a covariate in our analyses. However, contrary to expectations, previous dental visits appeared to be a significantly protective factor toward dental anxiety levels. In other words, previous visits to the dentists were associated with lower anxiety levels. Although most of the children had no previous visits to the dentist, those who had previously visited the dentist did not have higher anxiety levels.
At present, despite this topic being relatively unexplored, dental anxiety seems to be rather related to a history of dental pain in preschool children. 11 In addition, it has been observed that people who have a series of painless appointments are less likely to develop dental anxiety than those who have previously experienced pain during treatment. 25 Thus, the history of pain experienced in previous dental appointments is probably a much better predictor of dental anxiety than the simple fact of whether the child has or has not previously visited the dentist.
Despite the need for more studies to individually pinpoint the specific roles of each variable on dental anxiety levels in children, our present findings offer relevant information on the major factors associated with dental anxiety in preschool children. This could help dentists better understand children's behavior in dental settings as well as encourage clinicians to use psychological strategies to enhance trust in children with dental anxiety. However, a limitation of this study is its sample size, which does not allow for extrapolation of the results to the general population. For this reason, future studies with a representative sample size are needed. In addition, the low dental anxiety levels correlated with older age and previous dental visits could have partly resulted from the interviews being conducted in the waiting room and before the child knew his/her dental conditions. However, the FIS application protocol stipulates that the child be approached outside the examination/treatment room before the start of the examination/treatment session.
Taken together, our results provide important information for pediatric dentists to determine the most appropriate clinical management, focusing not only on minimally invasive treatments but also on procedures that cause the least possible pain to the child.

Conclusions
Older age is associated with low dental anxiety. More number of siblings is associated with dental anxiety in preschool children, whereas severity or extent of dental caries is not associated with dental anxiety.