Reliability and Validity of Scales for Assessing Child Dental Fear and Anxiety.

INTRODUCTION: Children with high dental anxiety display uncooperative behavior during dental procedures. Different self-assessment questionnaires are in use to estimate the prevalence of dental fear and anxiety (DFA) in children but they need to be tested for reliability and validity in different populations.
OBJECTIVES: The aim of this study was to test the reliability and validity of two scales for the assessment of child dental fear and anxiety in a sample of Croatian children.
MATERIAL AND METHODS: The sample comprised 202 pairs consisting of children and their mothers (97 boys and 105 girls) aged 5 - 12 years. Two scales were used to assess children's DFA: the Children's Fear Survey Schedule - Dental Subscale (CFSS-DS) and the Modified Child Dental Anxiety Scale - face version (MCDAS-f). The Corah's Dental Anxiety Scale (CDAS) was used in the sample of children's mothers. The average scores of cooperative children and children with behavior management problem (BMP) were compared.
RESULTS: Cooperative children displayed significantly lower CFSS-DS scores than children with BMP (M = 28. 46 vs. M = 39. 36; P < 0.001). The average MCDAS-f score was significantly higher in children with BMP than in cooperative children (M = 28. 07 vs. 20. 01; P < 0.001). The CFSS-DS showed high internal consistency (Cronbach's α = 0. 90), while internal consistency of MCDAS-f was good (α = 0. 73). The maternal CDAS showed good internal consistency (α = 0, 89). The correlations with other self-report measurements of DFS show good validity of all scales. The correlations between CFSS-DS and MCDAS-f were highly significant (r = 0.482; P < 0. 01) as well as the correlations of CFSS-DS and MCDAS-f with CDAS scores (r = 0.223; P < 0. 01 and r = 0.198; P < 0. 01, respectively.
CONCLUSION: The obtained results suggest that both the CFSS-DS scale and the MCDAS-f scale are reliable and valid scales for measuring dental fear and anxiety in children in a sample of Croatian children. The MCDAS-f scale has shown slightly lower internal consistency but it is suitable for use in young children. In addition, the MCDAS-f scale is simple to administer.

Introduction

Dental treatment of children is frequently associated with anxiety and uncooperative behavior. Dental fear and anxiety (DFA) in children is widespread and its prevalence ranges from 6 – 20% (). Different instruments have been used to assess DFA in children. The commonly used scale that was primarily designed to measure DFA in adults (, ) is the Corah Dental Anxiety Scale (CDAS). Additionally, this instrument has been successfully used in many studies with children (-). The CDAS has been shown to be a reliable and stable scale. Besides, a significant relationship between the CDAS and the Frankl's Rating Scale has been observed ().

The Children’s Fear Survey Schedule – Dental Subscale (CFSS-DS) was a scale especially constructed for use in children (). This instrument has been widely used in children. The CFSS-DS has been studied in many countries and showed good internal reliability and validity (-). Cultural differences may play an important role in the reliability of similar scales for the assessment of DFA in children (, , ).

Wong et al. () developed the Modified Child Dental Anxiety Scale (MCDAS) for the use with 8- to 15-year-old children. This scale is based on the Corah Dental Anxiety Scale (CDAS) and it includes eight questions to assess anxiety in different dental situations. A five-point Likert scale is used to score the level of dental anxiety (, ). However, the (MCDAS) scale is not suitable for the assessment of dental anxiety in very young children who are not capable of good cognitive functioning.

Howard and Freeman () created the Modified Child Dental Anxiety Scale; – Faces Version (MCDAS-f), by modifying the MCDAS by adding of faces analogue scale to the original numeric form. The inclusion of faces to the corresponding numbers allows young and nervous children good cognitive functioning and proper assessment of dental anxiety. The evaluation of psychometric properties of MCDAS-f confirmed that it as a reliable measure of dental anxiety in children (). Since such scales have to be tested for reliability and validity in different populations and cultures, the aim of this study was to assess the reliability and validity of the CFSS-DS and the MCDAS-f in a sample of Croatian children.

Materials and methods

The sample and its structure: An assessment of dental anxiety was carried out in the clinical population of Croatian children and their mothers. The sample comprised 202 children (97 boys, and 105 girls), aged from 5 to 12 years, who were coming to the dental office for dental treatment. The children and their mothers were invited to come to a dental office for dental examination and assessment of dental fear and anxiety (DFA). The children were randomly selected for the study, and all of them were of good general health. All children’s parents were fully informed of the nature and purpose of the study; hence, they gave their consent.

Survey instruments and procedures: a pediatric dentist and children obtained children’s behavior ratings prior to treatment. Two scales were used for assessing a child’s DFA: the Modified Child Dental Anxiety Scale - Faces Version (MCDAS-f) () and the Children’s Fear Survey Schedule – Dental Subscale (CFSS-DS) (). The Corah Dental Anxiety Scale (CDAS) was used (, ). Individual items of the scale were read out to a child and the child was asked to answer based on facial images on the MCDAS-f scale prior to treatment. The children were shown five images of human faces. Subsequently, they were asked to choose one picture reflecting their feeling in the best way. The questionnaire was administered to each child before dental examination in the dental office after an explanation by one of the authors had been given. The children were not allowed to consult their mothers who were present during the completion of the questionnaire. Dental anxiety in mothers was assessed by the commonly used Corah's Dental Anxiety Scale (CDAS) measuring reactions to four different dental situations on a five-point scale (, ). Mothers were asked to fill in the CFSS-DS questionnaire for their children and the CDAS for themselves.

Data analysis: The differences in anxiety scores between the groups of children with cooperative behavior and anxiety with behavior management problem were tested by the Student's t-test or the Mann-Whitney test. All variables, such as total scores of scales, showing normal distribution, were analyzed by using parametric tests (t-test for independent samples). A nonparametric test (the Mann-Whitney test) was applied to the variables that did not show normal distribution. Different Spearman's rank correlations were computed to examine the relationship between three scales for dental fear and anxiety. The correlation coefficients between anxiety scores of self-reported measurements obtained for children and their mothers were calculated to establish the validity of scales (, -). The Cronbach's alpha value was calculated to assess the internal reliability of the scales. The index is based on the number of variables of the instrument and correlation coefficients among them since it is considered the most adequate index for assessing the reliability of the scales (, , ).

Results

Differences in total scores of the Children's Fear Survey Schedule - Dental Subscale (CFSS-DS) regarding sexes and age were not statistically significant. Total scores of CFSS-DS were not normally distributed because the curve was skewed to the lower scores (Figure 1). The Mann-Whitney test was used to compare the obtained scores. All subjects were analyzed together and they displayed the average score of 30. 84 (n=202, SD=9, 58) (Table 1). Children with dental anxiety and behavior management problems (BMP) displayed significantly higher average score (M = 39. 36) than the group of non-anxious children with cooperative behavior (M = 28. 46) (P< 0.001).

Figure 1

Distribution of CFSS-DS scores (scores are not normally distributed because a majority of children scored low)

Table 1

Mean scores of dental anxiety scales and differences between non anxious cooperative and anxious children with behaviour management problem (BMP)

Questionnaire/ Scale	Behaviour	n	M	S.D.	P
Child Fear Survey Schedule – Dental Subscale (CFSS-DS)	Cooperative	158	28.46	7.69	<0.001a
	Anxiety and BMP	44	39.36	10.85
	Total	202	30.84	9.58
Modified Child Dental Anxiety Scale – faces version (MCDAS-f)	Cooperative	158	20.01	4.58	<0.001 b
	Anxiety and BMP	44	28.07	4.69
	Total	202	21.77	5.67
Corah Dental Anxiety Scale (CDAS)*	Cooperative	158	10.05	3.05	0.201a
	Anxiety and BMP	44	11.05	3.89
	Total	202	10.27	3.27

Legend: M – mean; S.D. – standard deviation; BMP – behaviour management problem

a Mann-Whitney test, b t-test for independent samples

*CDAS scores obtained for mothers of cooperative and BMP children

The differences in a total score of MCDAS-f regarding sexes and age were not statistically significant and were on average 21. 77 (n=202, SD=5. 67). Significant differences between children with cooperative behavior and anxious children with BMP were obtained by comparison of MCDAS-f scores. The values of total MCDAS-f score showed the normal distribution in the present sample (Figure 2). The Student's independent t-test was used to test the significance of differences between the groups of children. While the co-operative children displayed an average MCDAS-f score of 20. 01, the children with BMP showed a significantly higher mean score (M = 28. 07), which was statistically highly significant (P < 0.001).

Figure 2

Normal distribution of the Modified Child Dental Anxiety Scale - Faces Version (MCDAS-f) scores

Mothers of children with cooperative behavior and children with BMP did not differ significantly regarding the level of dental anxiety assessed by the CDAS. The distribution of CDAS scores from 4 to 20 did not follow a normal distribution (the Kolmogorov-Smirnov test: Z=2.082, p<0.001). In the analysis of obtained scores, nonparametric tests were used.

Reliability of Children's Fear Survey Schedule - Dental Subscale (CFSS-DS) was assessed by the computation of Cronbach's α coefficient (Table 2). The resulting α value of 0.90 indicates a very high reliability of (CFSS-DS) test in assessing a child's fear and dental anxiety from dental treatment.

Table 2

Reliability of Children's Fear Survey Schedule-Dental Subscale (CFSS-DS)

Item of scale	Item-Total Statistics
	Scale Mean ifItem Deleted	Variance	Cronbach'sAlpha if ItemDeletedα
Dentists	28.6584	75.6987	0.8910
Doctors	29.1188	82.0256	0.8984
Injections (shots)	27.9406	79.2900	0.9002
Having somebody examine your mouth	29.1584	79.3380	0.8941
Having to open your mouth	29.4604	83.0954	0.8978
Having a stranger touch you	29.1931	83.2710	0.9006
Having somebody look at you	29.3119	86.8226	0.9061
The dentist drilling	27.7772	75.2984	0.8944
The sight of the dentist drilling	28.3911	76.4881	0.8907
The noise of the dentist drilling	28.3960	76.3996	0.8909
The dentist putting instruments in your mouth	28.6436	77.4146	0.8906
Choking	27.9356	81.3640	0.9027
Having to go to the hospital	29.2426	86.2443	0.9131
People in white uniforms	29.4158	84.9506	0.9004
Having the dentist clean your teeth	29.0693	79.5076	0.8930
Cronbach α			0.9040

The reliability of the Modified Child Dental Anxiety Scale - faces version (MCDAS-f) was assessed by calculation of a Cronbach's α coefficient. All Cronbach α coefficients for each item and behavior of other items, if one item is deleted, are listed in Table 3, thus giving an insight into the uniformity of the items that make up the CFSS-DS test. The total value of Cronbach's α coefficient of 0. 73 displayed acceptable reliability of the MCDAS-f in self-assessment of child's dental anxiety. All items of Cronbach’s alpha showed a good internal consistency when one item was deleted. The assessment was based on the sum of total scores obtained by the MCDAS-f, which are theoretically in the range from 8 to 40.

Table 3

Reliability of Modified Child Dental Anxiety Scale - faces version (MCDAS-f)

Item of scale	Item-Total Statistics
How do you feel …	Scale Mean if Item Deleted	Variance	Cronbach's Alpha if Item Deletedα
… about going to the dentist generally?	19.5792	25.4987	0.6866
… having your teeth looked at?	19.7030	25.8616	0.6819
…having your teeth scraped and polished?	19.5891	25.9249	0.6969
… having an injection in the gum?	17.7871	26.5565	0.7016
… having a feeling?	18.8911	24.6050	0.6920
… having a tooth taken out?	18.4851	25.3256	0.7122
… being put sleep to have treatment?	19.2030	25.5556	0.7305
… having a mixture of ’gas and air’ which will help you feel comfortable for treatment but can not put you to sleep?	19.1337	25.4298	0.7045
Cronbach α			0.7280

The reliability of the CDAS scale was assessed by means of a Cronbach's α coefficient that is based on the internal consistency of this instrument. Table 4 shows the Cronbach’s α coefficient for each item of the scale and α score for the total CDAS scale. A total α coefficient was 0. 89, which means that there was a good internal consistency or good reliability of CDAS in the assessment of dental anxiety.

Table 4

Reliability of Corah’s Dental Anxiety Scale (CDAS)

Item of scale	Item-Total Statistics
	Mean	Variance	Cronbach's Alpha if Item Deletedα
If you had to go to the dentist tomorrow, how would you feel about it?	7.3564	7.1957	0.8797
When you are waiting in the dentist's office for your turn in the chair, how do you feel?	7.9950	6.3930	0.8528
When you are in the dentist's chair waiting while he gets his drill ready to begin working on your teeth, how do you feel?	7.5248	5.3949	0.8390
You are in the dentist's chair to have your teeth cleaned. While you are waiting and the dentist is getting out the instruments that he will use to scrape your teeth around the gums, how do you feel?	7.9257	5.8999	0.8511
Cronbach α			0.8889

The Spearman's rank correlation coefficients showed a significant association between all three scales (Table 5). There was a high positive correlation between total scores of CFSS-DS and MCDAS-f scales (r = 0,482; P < 0.01). The CDAS scores showed a significant positive correlation with CFSS-DS (r = 0.223; P < 0.01), while the correlation with MCDAS-f was lower but still significant (r = 0.198; P < 0.01). All three scales showed good validity in assessing the child’s behavior in dental situations.

Table 5

Spearman's correlation coefficients between total scores of three scales for assessment of dental fear and anxiety (n = 202)

Variables	CDAS	CFSS-DS	MCDAS-f
CDAS	---	0.223***	0.198***
CFSS-DS	0.223***	---	0.482***
MCDAS-f	0.198***	0.482***	---

Legend: CDAS – Corah Dental Anxiety Scale; CFSS-DS – Child Fear Survey Schedule-Dental Subscale; MCDAS-f - Modified Child Dental Anxiety Scale - faces version

*** P < 0.01

Discussion and conclusions

The research on dental fear and anxiety (DFA) in children in different countries has often revealed different results due to the specific cultural environment and differences in child-rearing practices. Cultural and social differences vary considerably between countries. Likewise, normative data vary for each measure in different populations. Since existing measures for evaluation of dental anxiety in children are not sensitive enough for the objective assessment, there is a need for development of new instruments (). Such an instrument should be culturally sensitive and provide an objective assessment of dental anxiety in a specific population of children.

The average score of CFSS-DS in a Croatian sample in this study was 28.46 for non-anxious and cooperative children, while anxious children with BMP displayed a significantly greater score of 39. 36. The difference in the average score between cooperative children and children with BMP was statistically highly significant (P < 0,001). The average score for Chinese children aged 6 to 10 years was 21. 0 ± 6. 57. The mean scores of the CFSS-DS in different populations show considerable variations ranging from 22.1 to 37.0 (, , -). We have not observed a significant difference between boys and girls in this study and both sexes were analyzed together. Ma et al. () also did not find significant differences in CFSS-DS mean scores among children of different ages.

Majstorovic et al. () examined dental anxiety in Croatian children using CDAS and CFSS-DS. In the sample of 165 children aged from 5 to 15 years, they established high reliability of CFSS-DS (Cronbach's α = 0, 8348) and satisfactory reliability of CDAS with Cronbach's α of 0. 7896. A higher α coefficient obtained for CFSS-DS was attributed to children's difficulties with understanding of the CDAS scale. The CDAS has been frequently used because of its simplicity and because it can be completed in a shorter time.

The mean score of CFSS-DS for Croatian sample obtained by Majstorovic et al. () was 27. 02, which is similar to the results obtained in some other studies. The mean scores in studies based on the parental version of CFSS-DS varied from 23.1 to 29.7 (, , , ). A recent study with a modified version of CFSS-DS delivered very high internal consistency reliability (Cronbach's α = 0, 90) and high factorial validity ().

A single measuring instrument that is currently available cannot measure multifactorial nature of dental anxiety adequately. Such a scale should comprise a child's age, developmental and cognitive aspects, and child-rearing conditions, psychosocial and economic conditions of a child's environment ().

Various instruments have been used for the assessment of dental fear and anxiety in children. Out of many scales, the Children's Fear Survey Schedule – Dental Subscale (CFSS-DS) became widely accepted as a highly reliable and valid instrument (, , , ). However, this scale does not provide a satisfactory application in very young children ().

Folyan and Kolawole () have pointed to the need for the development of an instrument that would enable young children to pick and point out a picture that illustrates the perceived child's emotion and anxiety. Such an instrument would be easily administered and used in children with limited cognitive and linguistic abilities. Howard and Freeman () have developed such an instrument. This instrument was scheduled to measure dental fear and anxiety in young children and is known as the MCDAS-f. They () proposed a new version of the MCDAS by adding faces to each item of a child’s responses in the questionnaire. This new instrument was more suitable for very young and nervous children. Its main advantages are that it is simple, easy for administration and suitable for use in young children. Patients can point the face that expresses their feeling at this moment ().

So far, there have not been any studies on Croatian children to establish reliability and validity of the MCDAS-f scale. The confident measures for assessing a child's dental fear and anxiety should be simple for application and understandable to young children to provide an objective assessment of their dental anxiety (). The MCDAS-f provides administration in children with limited cognitive and linguistic abilities and is suitable for both young and older children.

The MCDAS-f total score for children with cooperative behavior in the present sample (M = 20, 01) was almost the same as the normative score (M = 19.81) obtained by Howard and Freeman (). The values of a total MCDAS-f score showed normal distribution in the present sample, and the Student’s t-test was used to test differences in total scores between cooperative non-anxious and anxious children with BMP. The result showed that anxious children with BMP displayed significantly higher MCDAS-f score than non-anxious children (28. 07 vs. 20. 01; P < 0.001). The MCDAS-f in Howard and Freeman () study showed good validity and reliability with a Cronbach’s alpha of 0. 82.

In the present study, the CFSS-DS showed a high level of reliability with Cronbach’s α of 0.90. The internal consistency of this instrument was reported to range from 0. 83 to 0. 92 (, -, , -). Regarding the issue of reliability, Streiner et al. () pointed out that measuring scales with high reliability have to be used. Cronbach’s α of 0.70 can be considered the minimum value of reliability. A test with a reliability of 0.80 would require a 25 per cent increase in sample size, and reliability of 0.70 would require a 43 per cent larger number of subjects ().

The CDAS for the assessment of mothers’ dental anxiety in the present study showed good internal consistency reliability (Cronbach’s α = 0. 89) with an average score of 10. 05. The level of dental anxiety in mothers of non-anxious and cooperative children did not differ significantly from the mean score of mothers whose children displayed high dental anxiety and behavior management problem.

Karras () has pointed out that the validity coefficient of a test equals the coefficient of correlation between the test and its reference criterion. Although the coefficients of 0.80 are considered desirable, the significant coefficients could be based on the p-values of the correlation. Therefore, even much lower values of correlations could mean that a particular test is highly valid.

The Spearman's rank correlation coefficients in the present study showed significant association between CFSS-DS scores and MCDAS-f (r = 0.482; P < 0. 01). The significant correlations suggest good validity of MCDAS-f in a Croatian sample of children. The children's ratings on the CFSS-DS and MCDAS-f showed significant correlations with their mothers’ level of dental anxiety assessed by CDAS (r = 0.223 and r =0.198; P < 0. 01, respectively), thus suggesting the influence of mothers’ anxiety on their children’s dental anxiety. The MCDAS-f was significantly correlated with the CFSS-DS regarded as a “gold standard” for assessing child dental anxiety (). A high correlation between the CFSS-DS and CDAS scales was found in other studies (, ). They have concluded that these scales provide good tools for the assessment of dental anxiety in children.

A high value of Cronbach's alpha (α = 0.8641) led the authors of this paper to conclude that two rating scales provide highly reliable instruments for the assessment of children’s dental fear and anxiety in a dental office before dental procedures. The MCDAS-f and CFSS-DS showed a significant correlation and represent valid and suitable assessment tools for the assessment of dental fear in children. The MCDAS-f scale can be used in young children with limited cognitive and language skills. It is a suitable, simple to administer and reliable instrument for assessing dental anxiety in young children.