Can A Funny Story about Tooth Brushing Decrease Plaque Scores in Children? A Longitudinal Field Experiment

Figures & data

Figure 1. Theoretical model of the study. Arrows express expected effects

Table 1. Sample size, age, and gender distribution at the first measurement (T1), second measurement (T2), and third measurement (T3) in the total sample and the two experimental groups

	T1			T2			T3
	N	Age in years M (SD)	Gender	N	Age in years M (SD)	Gender	N	Age in years M (SD)	Gender
Total	94	6.41 (1.37)	52 M; 42 F	661	6.52 (1.41)	34 M, 27 F	63	6.51 (1.34)	35 M, 28 F
Story condition	46	6.46 (1.35)	26 M, 20 F	335	6.40 (1.42)	20 M; 15 F	31	6.42 (1.26)	17 M; 14 F
Expository condition	38	6.37 (1.40)	26 M; 22 F	226	6.69 (1.41)	14 M; 12 F	32	6.59 (1.43)	18 M; 14 F

Table 2. Brief summary of session at the three time points of assessment

	Summary of sessions
Time 1	Checking inclusion criteria. Parents sign informed consent. Pre-intervention measures in dental practice. Assessing baseline dental health-related intention and attitude toward tooth brushing, dental anxiety, and dental plaque score. Randomly assigning child to one of the two experimental conditions.
Time 2	Two weeks after T1. Online survey assessing intention and attitude toward tooth brushing, children’s responses to the experimental materials (enjoyment, wishful identification, parasocial relationship, perceived similarity, moral judgment), parents’ perception of the texts, and control questions.
Time 3	Two weeks after T2. Post-intervention measures in dental practice, approximately one month later. Assessing dental anxiety, intention and attitude toward tooth brushing, and dental plaque score.

Table 3. Descriptives in the story and expository conditions. Mean and standard deviation (in brackets). P values of independent sample t-tests indicate if there was a significant difference between conditions in the output variables

Dependent variables	Expository condition	Story condition	t(df)	p
Character engagement	2.58 (0.86)	3.02 (0.87)	−1.93 (54.02)	.059
Perceived similarity	1. 96 (1. 25)	1. 95 (1. 22)	0.02(57)	.983
Wishful identification	2. 55 (1. 02)	2. 16 (1. 22)	1.31(57)	.197
Parasocial relationship	2. 53 (1. 02)	3. 64 (0. 95)	−4.30 (57)	<.001
Liking	2.81 (0.84)	3.44 (0.96)	−2.67(57)	.009
Enjoyment (child)	2. 82 (1. 26)	4. 25 (0. 92)	−4.86(44)	<.001
Moral judgment	2.54 (1.11)	3.35 (1.37)	−2.45(57)	.017
Reading frequency (child)	2. 58 (1.90)	4. 00 (3. 05)	−2.22(56)	.031
Reading frequency (parent)	4. 81 (1. 88)	5. 29 (2. 54)	−0.85(58)	.397

Table 4. Descriptives of output variables across time. F statistics indicates the interaction effect of condition and time on the dependent variable

	T1	T2	T3	F (df, error)	p	Effect size
Attitude toward tooth brushing				0.31 (2, 184)	.658	.003
Story condition	3.42 (1.30)	3.46 (1.00)	3.33 (1.14)
Expository condition	3.32 (1.18)	3.36 (1.00)	3.43 (1.02)
Intention toward tooth brushing				0.15 (2, 184)	.82	.002
Story condition	3.60 (1.24)	3.80 (1.11)	3.71 (1.21)
Expository condition	3.26 (1.18)	3.55 (1.23)	3.51 (1.27)
Child’s dental anxiety state (Child)				0.64 (1, 92)	.478	.005
Story condition	1.80 (0.81)	n.d.	1.92 (0.74)
Expository condition	2.03 (1.01)	n.d.	2.02 (1.00)
Plaque score				4.01 (1, 92)	.048	.042
Story condition	0.67 (0.63)	n.d.	0.80 (0.65)
Expository condition	0.75 (0.56)	n.d.	0.65 (0.64)

Note. n.d. = no data

Table 5. Results of Mediation Model (Model 6, Hayes, 2013). Partially standardized indirect effect(s)

Indirect effect type		b	SE	[LL, UL BCa 95% CI^a]
Ind1	Condition → Character engagement → Plaque score change	−0.07	0.09	[−0.29, 0.09]
Ind2	Condition → Moral judgment → Plaque score change	−0.18	0.11	[−0.43, −0.01]
Ind3	Condition → Enjoyment → Plaque score change	0.42	0.20	[0.09, 0.86]
Ind4	Condition → Character engagement → Moral judgment → Plaque score change	−0.02	0.03	[−0.10, 0.02]
Ind5	Condition → Character engagement → Enjoyment → Plaque score change	0.09	0.06	[−0.01, 0.23]
Ind6	Condition → Moral judgment → Enjoyment → Plaque score change	0.04	0.04	[−0.03, 0.11]
Ind7	Condition → Character engagement → Moral judgment → Enjoyment → Plaque score change	0.00	0.01	[−0.01, 0.03]

^aBootstrap sample size = 10 000; Ba 95% CI, bias-corrected and accelerated confidence interval; LL = lower limit; UL = upper limit.

NB Bold indicates significant paths.

Figure 2. Mediation analysis with conditions as predictor, plaque score change as dependent variable, age as covariate, and character engagement, child’s enjoyment and moral judgment of the protagonist as mediator variables. A bootstrap method with 10,000 resample was used, bootstrapped intervals are reported for indirect effects

Hayes, A. F. (2013). Introduction to mediation, moderation, and conditional process analysis: A regression-based approach. Guilford Publications.

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