Risk Indicators for Noncavitated and Cavitated Carious Lesions in Preschool Children

Abstract

Objective

The aim of this study was to evaluate the risk indicators associated with noncavitated and cavitated lesions in preschool children.

Methods

The cross-sectional study included 3- to 4-year-old healthy children (N = 741) recruited in a randomised controlled clinical trial. After obtaining written informed consent, parents completed a questionnaire about their child's sociodemographic background and oral health–related behaviours and parents' oral health–related knowledge and attitude. Caries and plaque were evaluated using International Caries Detection and Assessment System-II and Visible Plaque Index (VPI), respectively. Children were grouped according to their oral health status as being caries-free (CF), having only noncavitated lesions (NC), or having cavitated lesions (CL). The least absolute shrinkage and selection operator (LASSO) sparse multinomial regression was used to study the variables using 1 standard error above the minimum criterion set at P < .05.

Results

The prevalence of children with NC and CL was 29.1% and 49.4%, respectively, with a prevalence of early childhood caries being 78.5%. The proportion of children who brushed twice or more than twice a day was highest in CF (71.7%), followed by NC (58.3%), and was least in CL (57.7%). A higher percentage of CL children (56.2%) had twice or more than twice the frequency of between-meal snacking than CF (41.7%) and NC (41.1%) (P < .001) children. The variables included with non-zero coefficients in the model were mean parental oral health knowledge, attitude score, and children's mean VPI score, and all were significant for CL; however, in NC, only VPI score was found to be significant.

Conclusions

Poor oral hygiene is the risk indicator associated with the presence of NC in preschool children, whilst poor oral hygiene and poor parental oral health knowledge and attitude are associated with the presence of cavitated lesions.

Introduction

Early childhood caries (ECC) is considered one of the most common chronic diseases amongst preschool children globally and remains a concern due to its devastating and rapidly progressing nature, necessitating evaluation of multiple aetiologic factors for its prevention. A review reported that ECC prevalence varies from 23% to 90% across different countries, with most studies reporting its prevalence to be higher than 50%.¹ Mean caries prevalence worldwide for 3-, 4-, and 5-year-old children is reported to be 43%, 55%, and 63%, respectively, a large portion of which is untreated.² Moreover, the latest territory-wide survey conducted in Hong Kong indicated its prevalence amongst 5-year-olds as 55% and found that more than 90% of decayed teeth were left untreated. In addition, its distribution was uneven, with 81% of the caries lesions found in 26% of the children.³

Children's parents or caregivers play an essential role in creating an environment necessary to establish healthy habits and behaviours in the child.⁴ Also, factors like parents’ socioeconomic status, education, and oral hygiene–related attitudes and behaviours shape the foundation of a child's dental habits during their early childhood years, thus influencing its oral health status.⁵ Caries puzzle also emphasises the importance of the interplay of multiple strategies for preventing and controlling caries for a child's cavity-free future. One of the components of this puzzle includes parents education about oral health for behaviour change.⁶

Dental caries clinically manifests as a noncavitated or cavitated lesion, depending on the discontinuity in enamel.⁷ Determining lesion severity is essential, as it helps dental professionals plan the needed early interventions and preventive treatments. Lesion severity has been evaluated either at the cavitated level using decayed-missing-filled-teeth (dmft) index or at both cavitated and noncavitated levels using International Caries Detection and Assessment System (ICDAS) criteria but transforming into the dmft format for analysis purposes.8, 9, 10, 11 However, ICDAS criteria have been found to generate reliable and reproducible data in epidemiologic surveys for caries assessment compared to other measures, in addition to providing information about initial noncavitated lesions.^12,13

Despite the high prevalence of ECC, few studies have reported the association of various risk indicators with noncavitated and cavitated carious lesions separately.^14,15 The information is of great relevance to public health planning that target caries-preventive measures differently for noncavitated and cavitated lesions in children at high risk.¹⁶ Masking the importance of preventing initial noncavitated lesions may leave them unnoticed and lacking intervention, increasing the risk of progression into cavitated lesions and causing a financial burden on parents and society. Therefore, this study aimed to determine the risk indicators associated with the presence of these lesions amongst preschool children in Hong Kong.

Methods

The study was conducted in Hong Kong with prior ethical approval from the Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (IRB: UW 18–054) and following the principles of the 1964 Helsinki declaration. In addition, written informed consent was obtained from parents before conducting the examination. Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for cross-sectional studies was followed for reporting the analysis.¹⁷ The data that support the findings of this study are available on reasonable request from the corresponding author.

The data for this cross-sectional analysis are from the baseline of a randomised controlled clinical trial (https://clinicaltrials.gov/ct2/show/NCT04274569) conducted in 25 kindergartens of Hong Kong. Preschool children with diverse socioeconomic backgrounds were selected and invited to participate in this trial, with recruitment done in March through June 2019. Generally, healthy 3- and 4-year-old children were eligible to be included in the study. Children with any severe systemic disease, special needs, or long-term medication and those who were uncooperative during clinical examination were excluded.

The information sheet describing the study objectives and procedures, along with a structured validated questionnaire (adapted from one used in a previous survey¹⁸) written both in Chinese and English, was distributed to the parents. The questionnaire consisted of 3 parts associated with the following information:

• 1.Child's socioeconomic background information: gender, age, birthplace, primary caregiver, parents’ education level, and monthly family income
• 2.Child's and parent's oral health–related behaviours: child's feeding and toothbrushing habits, frequency of between-meal snacking, and previous dental visit and parent's toothbrushing habits and caries experience
• 3.
  Child's parent's oral health knowledge and attitude

  • a.
    Knowledge scores: Parents’ oral health knowledge was measured through 2 multiple-choice questions about causation and prevention of caries, having 3 correct options for the questions, and for each choice of the correct answer, a score of 1 was given. Parents’ oral health knowledge score was calculated as a sum of the scores of 2 questions, thus ranging from 0 to 6, with a higher score indicating better oral health knowledge.
  • b.
    Attitude scores: 10 multiple-choice questions in a 5-point Likert scale ranging from “strongly agree” to “strongly disagree” were asked to calculate the parents’ attitudes on their children's oral health. For positively worded statements, “strongly agree” and “agree” responses were classified as positive attitudes, whilst “strongly disagree” and “disagree” responses were classified as negative attitudes. Conversely, for negatively worded statements, “strongly agree” and “agree” responses were regarded as negative attitudes, whilst “strongly disagree” and “disagree” were considered positive attitudes. Statements with option “neither” were evaluated as a neutral response. Every positive, neutral, and negative response was scored as 1, 0, and −1, respectively. Therefore, parents’ attitude scores ranged from −10 to 10, with a higher score reflecting a more positive attitude towards the child's dental health.

Missing and inappropriately marked answers in the questionnaire were verified by making phone calls to the parents; however, some opted not to answer a few questions about their background, and the data pertaining to these areas were considered missing in the final analysis.

Clinical examination was conducted in the kindergarten classrooms by 1 trained dentist who underwent calibration exercises for caries diagnosis in the same setting prior to the start of the study. On the same day, a 10% random sample was selected by another dental assistant without notifying the examiner to assess the intra-examiner agreement. Examination was performed using a disposable mirror with a light-emitting diode (LED) light and a 0.5-mm ball end Community Periodontal Index (CPI) probe in a supine position after removing food debris, if any, for proper caries inspection.

International Caries Detection and Assessment System (ICDAS II; International Caries Detection and Assessment System Coordinating Committee, 2009) criteria were used for caries diagnosis with some modifications.¹¹ No air blowdrying of the teeth was carried out due to the community settings. Therefore, code 1 was not used. Codes 2 through 6 were followed; however, codes 7 through 9 were added for filled tooth surfaces with or without caries (code 7 and 8, respectively) and missing tooth due to caries (code 9). Missing tooth due to other reasons was assigned code “99.”

Dental plaque was evaluated using a dichotomous index as the absence/presence of visible plaque on labial/buccal and lingual/palatal surfaces of 6 index primary teeth (right maxillary second molar, right maxillary central incisor, left maxillary canine, left mandibular second molar, left mandibular central incisor, and right mandibular canine) and calculated as a Visible Plaque Index (VPI) by determining the percentage of tooth surfaces with visible plaque. At the end of the examination, parents were provided with the child's oral health report to seek appropriate dental treatment if necessary. Children were classified into 3 groups according to their oral health status:

• 1.Caries-free children (CF): no clinical evidence of caries (ie, ICDAS score = 0 on all teeth)
• 2.Children with only noncavitated carious lesion or lesions (NC; ie, ICDAS score = 2 on at least 1 tooth)
• 3.Children with cavitated carious lesion or lesions with or without simultaneous noncavitated lesions (CL; ie, ICDAS score = 3-6 on at least 1 tooth with or without ICDAS score = 2 on any other tooth)

Statistical methods

Two investigators independently entered the data and verified any errors using Microsoft Excel. Statistical Package for Social Science version 27.0 (IBM Corp.) was used for analysing data. The normality of the data was checked using Kolmogorov–Smirnov test and Shapiro–Wilk test followed by independent-samples Kruskal–Wallis test when appropriate. For pairwise comparisons, Bonferroni corrections were used, and for discrete variables, the chi-square test was used. Fisher–Freeman–Halton exact test was used if the missing cell count was more than 20%. Model selection amongst possible independent variables was analysed by least absolute shrinkage and selection operator (LASSO) sparse multinomial regression using R package glmnet. In LASSO, 10-fold cross-validation was used, using 1 standard error above the minimum criterion. Statistical significance level was set at .05 for all tests at 95% confidence intervals (CIs). Kappa statistics were used to assess the intra-examiner agreement for clinical examination.

Results

A total of 837 children from 25 kindergartens of Hong Kong were invited; 741 (88.5%) children (355 boys and 386 girls) agreed to participate in the study, and the remaining 96 were excluded either because the questionnaire was not available or no examination could be performed (Supplementary Figure).

Table 1 depicts the background information of CF, NC, and CL children. The numbers of CF, NC, and CL children were 159 (21.5%), 216 (29.1%), and 366 (49.4%), respectively. The education levels of the mother (P < .001) and the father (P = .029) were found to be significantly different amongst the 3 groups. There was a higher proportion of children in the CF group (43.8%) than in the NC (30.5%) and CL (26.1%) groups whose mothers had postsecondary/university education levels. Similarly, there was a higher proportion of children in CF (42%), followed by NC (37.5%) and CL (27.2%) groups, whose fathers had postsecondary/university education levels.

Table 1.

Sociodemographic factors of the study population.

	CF	NC	CL	P value
	(N = 159)	(N = 216)	(N = 366)
Mean age, (y)	3.87 (N = 155)#	3.91 (N = 211)#	3.92 (N = 362)#	.249*
SD	0.32	0.35	0.35
95% CI	3.82–3.92	3.87–3.96	3.89–3.96
Gender, No. (%)				.541†
Female (n = 355)	76 (47.8%)	110 (50.9%)	169 (46.2%)
Male (n = 386)	83 (52.2%)	106 (49.1%)	197 (53.8%)
Place of birth, No. (%)				.289†
Hong Kong	153 (96.2%)	201 (93.1%)	339 (92.6%)
Other	6 (3.8%)	15 (6.9%)	27 (7.4%)
Caregiver (multiple choice), No. (%)
Mother	132 (83.0%)	176 (82.2%)#	300 (82.9%)#	.975†
Father	57 (35.8%)	68 (31.8%)#	97 (26.8%)#	.098†
Grandparents	46 (28.9%)	68 (31.8%)#	106 (29.3%)#	.780†
Helper	25 (15.7%)	35 (16.4%)#	48 (13.3%)#	.549†
Others	4 (2.5%)	10 (4.6%)#	17 (4.6%)	.495†
Mother's education level (y), No. (%)				<.001†
Primary (<6 y)	0 (0%)#	3 (1.4%)#	13 (3.7%)#
Junior secondary (7-9 y)	32 (20.9%)#	61 (29.1%)#	120 (34.1%)#
Higher secondary (10-13 y)	54 (35.3%)#	82 (39.0%)#	127 (36.1%)#
Postsecondary/university (>14 y)	67 (43.8%)#	64 (30.5%)#	92 (26.1%)#
Father's education level (y), No. (%)				.029‡
Primary (<6 y)	2 (1.4%)#	1 (0.5%)#	6 (2.0%)#
Junior secondary (7-9 y)	33 (23.1%)#	48 (26.1%)#	99 (33.2%)#
Higher secondary (10-13 y)	48 (33.5%)#	66 (35.9%)#	112 (37.6%)#
Postsecondary/university (>14 y)	60 (42.0%)#	69 (37.5%)#	81 (27.2%)#
Monthly household income, No. (%)				<.001†
<15,000 HKD	24 (15.3%)#	37 (17.4%)#	85 (24.1%)#
15,000-27,600 HKD	54 (34.4%)#	89 (41.8%)#	166 (47.2%)#
>27,600 HKD	79 (50.3%)#	87 (40.8%)#	101 (28.7%)#

The bold values are significant at p<0.05.

^#Some values are missing, as the parents or caregivers did not answer this question and opted not to disclose the information on follow-up.

^⁎Independent-samples Kruskal–Wallis test.

^†Pearson chi-square test.

^‡Fisher–Freeman–Halton exact test.

CF, caries-free group (no clinical evidence of caries, ie, ICDAS score = 0 on all teeth); CL, children with cavitated carious lesion or lesions; with or without simultaneous noncavitated carious lesions (ie, ICDAS score = 3-6 on at least 1 tooth with or without ICDAS score = 2 on any other tooth/teeth); CI, confidence interval; HKD, Hong Kong Dollars; ICDAS, International Caries Detection and Assessment System; NC, children with only noncavitated carious lesion or lesions in their oral cavity (ICDAS score = 2 on at least 1 tooth).

The monthly family income was classified on the estimates of the 2018 survey (Census and Statistics Department of Government of Hong Kong Special Administrative Region), wherein these ranges were divided as <25th percentile, 25th to 75th percentile, and >75th percentiles, thus considering less than 15,000 HKD (Hong Kong Dollars), 15,000 to 27,600 HKD, and more than 27,600 HKD as low, medium, and high family income.¹⁹ In addition, monthly family income was another risk indicator that was found to be significantly different (P < .001) amongst the groups, with a greater proportion of participants in the CF group (50.3%) having a higher income (>27,600 HKD) than the NC (40.8%) followed by the CL (28.7%) group.

Table 2 shows the oral health–related behaviour of children and their parents in the 3 groups. The child's toothbrushing frequency was significantly different amongst the groups (P = .007). Expectedly, a higher proportion of CF children (71.7%) brushed twice or more than twice a day, followed by children in the NC group (58.3%); the least proportion was in the CL group (57.7%). Additionally, the child's frequency of snacking between meals significantly differed amongst the 3 groups (P < .001). A higher percentage of children in the CL group (56.2%) had twice or more than twice the frequency of between-meal snacking than children in the CF (41.7%) and NC (41.1%) groups.

Table 2.

Oral health–related behaviours of children and parents.

	CF	NC	CL		P value
	(N = 159)	(N = 216)	(N = 366)
A. Child's dietary and oral hygiene habits, No. (%)
Frequency of child brushing				.007*
Once/less than once a day	45 (28.3%)	90 (41.7%)	155 (42.3%)
Twice/more than twice a day	114 (71.7%)	126 (58.3%)	211 (57.7%)
Type of toothpaste				.101*
No toothpaste	6 (3.8%)#	10 (4.7%)#	32 (8.8%)#
Nonfluoridated toothpaste	75 (47.8%)#	109 (50.9%)#	148 (40.5%)#
Fluoridated toothpaste	66 (42.0%)#	81 (37.9%)#	156 (42.7%)#
Uncertain	10 (6.4%)#	14 (6.5%)#	29 (8.0%)#
Supervision whilst brushing				.611*
Yes	153 (96.2%)	203 (94.0%)	346 (94.5%)
No	6 (3.8%)	13 (6.0%)	20 (5.5%)
Amount of toothpaste used				.896*
Small smear	33 (21.4%)#	46 (22.0%)#	84 (23.7%)#
Pea-size	102 (66.2%)#	134 (64.1%)#	230 (65.0%)#
Half/more than half length of brush head	19 (12.4%)#	29 (13.9%)#	40 (11.3%)#
Dental visit				.106*
Yes	28 (17.8%)#	22 (10.3%)#	48 (13.2%)#
No	129 (82.2%)#	192 (89.7%)#	316 (86.8%)#
Night bottle feeding				.473*
Yes	20 (12.7%)#	37 (17.3%)#	54 (14.9%)#
No	137 (87.3%)#	177 (82.7%)#	309 (85.1%)#
Frequency of snacking between meals				<.001*
Once/less than once a day	91 (58.3%)#	126 (58.9%)#	160 (43.8%)#
Twice/more than twice a day	65 (41.7%)#	88 (41.1%)#	205 (56.2%)#
Fed after brushing during night				.058*
Yes	77 (49.4%)#	128 (60.1%)#	217 (59.9%)#
No	79 (50.6%)#	85 (39.9%)#	145 (0.1%)#
B. Parents’/caregiver's dietary and oral hygiene habits, No. (%)
Parent's own toothbrushing					.093*
Once/less than once a day	20 (12.7%)#	46 (21.3%)	69 (18.9%)#
Twice/more than twice a day	138 (87.3%)#	170 (78.7%)	296 (81.1%)#
Parents/caregivers have tooth decay					.211*
Yes	104 (66.2%)#	127 (58.8%)	236 (64.5%)
No	46 (29.3)#	77 (35.6%)	102 (27.9%)
Unclear/don't know	7 (4.5%)#	12 (5.6%)	28 (7.7%)

The bold values are significant at p<0.05.

^#Some values missing as the parents or caregivers did not answer this question.

^⁎Pearson chi-square test

CF, caries-free group (no clinical evidence of caries, ie, ICDAS score = 0 on all teeth); CL, children with cavitated carious lesion or lesions with or without simultaneous noncavitated carious lesions (ie, ICDAS score = 3-6 on at least 1 tooth with or without ICDAS score = 2 on any other tooth/teeth); ICDAS, International Caries Detection and Assessment System; NC, children with only noncavitated carious lesion or lesions in their oral cavity (ICDAS score = 2 on at least 1 tooth).

Table 3 presents the knowledge and attitude scores of parents regarding oral health and hygiene practices. A significantly higher mean knowledge and attitude score of parents was found in the CF group, followed by the NC group and the least in the CL group (P = .001).

Table 3.

Knowledge and attitude scores of parents regarding oral health and hygiene practices.

	CF	NC	CL	P value	Pairwise comparison (Bonferroni correction for multiple tests)
	(N = 159)	(N = 216)	(N = 366)
Mean knowledge score (score range = 0 to 6)	5.03a	4.81b	4.49c	.001*	a = b and b = c; but a > c
SD	1.19	1.35	1.54
95% CI	4.84–5.22	4.63–4.99	4.33–4.65
Mean attitude score (score range= −10 to +10)	5.74a	5.44b	4.67c	<.001*	a = b > c
SD	2.65	2.92	3.05
95% CI	5.33–6.16	5.05–5.84	4.36–4.99

The bold values are significant at p<0.05.

^⁎Independent-samples Kruskal–Wallis test.

CF, caries-free group (no clinical evidence of caries, ie, ICDAS score = 0 on all teeth); CI, confidence interval; CL, children with cavitated carious lesion or lesions with or without simultaneous noncavitated carious lesions (ie, ICDAS score = 3-6 on at least 1 tooth with or without ICDAS score = 2 on any other tooth/teeth); ICDAS, International Caries Detection and Assessment System; NC, children with only noncavitated carious lesion or lesions in their oral cavity (ICDAS score = 2 on at least 1 tooth).

The caries and oral hygiene statuses of children are shown in Table 4. Another finding was the presence of significantly higher percentages of tooth surfaces with visible plaque in the CL group, followed by the NC group and the least in the CF group (P < .001).

Table 4.

Dental caries and oral hygiene status of the study population.

	CF	NC	CL	P value	Pairwise comparison using Bonferroni correction
	(N = 159)	(N = 216)	(N = 366)
VPI percentage, mean (SD)	19.63 (10.39)a	26.33 (12.98)b	29.60 (13.41)c	<.001*	c > b > a
No. of WSLs, mean (SD) (ICDAS score 2)	0.00 (0.00)a	3.28 (2.79)b	4.72 (4.05)c	<.001*	c > b > a
No. of decayed surfaces, mean (SD) (ICDAS scores 3 to 7)	0.00 (0.00)a	0.00 (0.00)b	6.35 (7.87)c	<.001*	c > a = b
No. of filled surfaces, mean (SD) (ICDAS score 8)	0.00 (0.00)a	0.00 (0.00)b	0.03 (0.28)c	.045*	a = b = c
No. of missing surfaces, mean (SD) (ICDAS score 9)	0.00 (0.00)	0.00 (0.00)	0.02 (0.30)	.358*
Decayed-missing-filled surfaces score, mean (SD)	0.00 (0.00)a	0.00 (0.00)b	6.40 (7.93)c	<.001*	c > b > a

The bold values are significant at p<0.05.

^⁎Independent-samples Kruskal–Wallis test.

CF, caries-free group (no clinical evidence of caries, ie, ICDAS score = 0 on all teeth); CL, children with cavitated carious lesion or lesions with or without simultaneous noncavitated carious lesions (ie, ICDAS score = 3-6 on at least 1 tooth with or without ICDAS score = 2 on any other tooth/teeth); NC, children with only noncavitated carious lesion or lesions in their oral cavity (ie, ICDAS score = 2 on at least 1 tooth); ICDAS, International Caries Detection and Assessment System; VPI, Visible Plaque Index; WSL, white spot lesion.

The LASSO sparse multinomial regression analysis was used after selecting 21 independent variables for CL and NC groups using 1 standard error above the minimum criterion and the CF group as a reference (Table 5). After LASSO analysis, the remaining variables found with non-zero coefficients were the parent's oral health knowledge and attitude and the child's VPI score. For the NC group, only VPI score was found to be significant (P < .001) in the final model and showed that children with a higher mean VPI score or poor oral hygiene had a higher risk of experiencing noncavitated lesions. For the CL group, the variables found to be significant in the final model were parental oral health knowledge (P = .001) and attitude (P = .011) and child's VPI score (P < .001). The kappa value for the intra-examiner agreement for caries assessment was 0.92, indicating excellent agreement.

Table 5.

Model analysis by least absolute shrinkage and selection operator (LASSO) sparse multinomial regression for the factors associated with development of cavitated and no-cavitated lesions.

Groups	Factors	B	SE	P value	Exp (B)	95% CI
						Lower	Upper
NC	Intercept	−0.196	0.497	.694
	Knowledge	−0.116	0.084	.164	0.890	0.756	1.049
	Attitude	−0.021	0.040	.592	0.979	0.906	1.058
	VPI percentage	0.052	0.010	<.001	1.054	1.033	1.075
CL	Intercept	0.785	0.454	.084
	Knowledge	−0.246	0.077	.001	0.782	0.672	0.910
	Attitude	−0.094	0.037	.011	0.910	0.846	0.979
	VPI percentage	0.071	0.010	<.001	1.074	1.054	1.094

The reference category is CF.

CF, caries-free group (no clinical evidence of caries, ie, ICDAS score = 0 on all teeth); CI, confidence interval; CL, children with cavitated carious lesion or lesions with or without simultaneous noncavitated carious lesions (ie, ICDAS score = 3-6 on at least 1 tooth with or without ICDAS score = 2 on any other tooth/teeth); ICDAS, International Caries Detection and Assessment System; NC, children with only noncavitated carious lesion or lesions in their oral cavity (ICDAS score = 2 on at least 1 tooth); VPI, Visible Plaque Index.

The bold values are significant at p<0.05.

Discussion

For a better understanding of caries and its risk assessment, it is essential to know the extent of its severity and the associated risk factors. A recent meta-analysis encompassing 89 studies identified the possible risk indicators of ECC and found that only 25.8% of the included studies were of high quality.²⁰ However, literature identifying the risk factors for the development of noncavitated or cavitated lesions in preschool children is scant. Thus, this study adds significantly to the understanding of risk indicators involved in the development of noncavitated and cavitated lesions in preschool children. LASSO analysis observed that parental oral health knowledge and attitude and visible plaque are significant caries risk indicators, similar to a previous study conducted in China.²¹

Variations in the caries assessment methods make it essential to focus on the target established by the World Health Organization (WHO)/FDI World Dental Federation for 2020 of having at least 50% caries-free children at 5 to 6 years of age.²² The present findings showed that almost one-third (29.1%) of children presented with noncavitated lesions only, and about one-half (49.4%) had cavitated (with or without noncavitated lesions) lesions. Only 21.5% of children were caries-free. This result is alarming and similar to a study indicating the need for early intervention to stop caries progression²³; further, it is in accord with earlier studies wherein 48% children had cavitated lesions²⁴ and 28% had noncavitated lesions in the primary dentition.²⁵ A recent study also reported a similar result, except that they used dmft index recommended by the WHO to diagnose caries, excluding initial noncavitated lesions.²⁶ Discounting the initial signs of carious activity might have led to curtailment of the importance of preventing incipient noncavitated lesions due to variations in caries assessment methods used, thus contributing to imprecise estimation of caries prevalence. It has been confirmed that noncavitated lesions impact the prevalence, extent of caries estimates, and risk assessment when using different diagnosing criteria.²⁷

The present study found that children having poor oral hygiene with presence of visible plaque have higher risk of experiencing noncavitated lesions. In addition to poor oral hygiene, poor parental oral health knowledge and attitude are associated with cavitated lesions. The plaque presence on tooth surfaces is a good indicator of oral hygiene status of an individual and has been associated with the initiation and severity of caries²⁸ and thus the development of noncavitated and cavitated lesions. The current study showed a lower proportion of children with noncavitated (58.3%) and cavitated lesions (57.7%) brushing their teeth twice/more than twice a day when compared with the caries-free group (71.7%). Therefore, the result is in accord with minimal intervention dentistry (MID),²⁹ emphasising the importance of proper plaque control through effective toothbrushing by parents to disrupt and remove the cariogenic biofilm, thereby preventing the progression of noncavitated lesions to cavitated lesions.

Parents’ oral health knowledge and attitude were found to influence the development of carious lesions, which is in line with a systematic review.⁵ This may be explained as parents with less knowledge about caries causation and prevention potentially caring less about their child's oral health and hygiene and thus resulting in the poor oral health of children. The parents' knowledge and attitude towards oral health reflect their choices and model for their children at home. As observed, a significantly higher proportion of children in the CF group had parents with better knowledge and a more positive attitude towards oral health when compared to children with cavitated or noncavitated lesions. Furthermore, the present study is in accordance with an earlier study³⁰ highlighting the importance of oral health education programmes to parents to improve their awareness towards oral health and establishing healthy eating and toothbrushing habits in their children for ECC prevention.

This study has several strengths, such as sufficient sample size with heterogeneity of the sample in terms of socioeconomic background, age, and gender, along with its geographic distribution. Also, we obtained a high response rate (88.5%) and high intra-examiner reliability for clinical examination (0.92) whilst using ICDAS II criteria for differentiating noncavitated and cavitated lesions. Last, a multinominal regression analysis using LASSO analysed and reported the impact of potential risk indicators associated with the development of carious lesions in a large representative sample of preschool children.

The study also has a few limitations; therefore, the results need to be interpreted cautiously. This cross-sectional study provides an association but not causation of the disease, which is related to the study's design and thus uses the term “risk indicators” rather than “risk factors.” Also, the sample was selected based on convenience sampling, which could have led to sampling error due to the restriction of including participants from small number of kindergartens whilst decreasing time and cost and increasing efficiency when conducting surveys. Thus, future studies are recommended to identify risk indicators longitudinally, possibly as prospective or case-control study designs. Moreover, the multifactorial nature of ECC demands the application of MID, with consideration of confounding factors when managing the development and progression of a carious lesion, such as the control over frequency and cariogenicity of the child's diet.²⁹ However, as the present study did not evaluate the complete diet history of the recruited children, this could be an insight for future studies to consider. In addition, the study did not assess the impact of caries experience on the child's quality of life, which has been shown to have implications when planning an effective evidence-based preventive approach.³¹

In conclusion, the study highlights the risk indicators associated with the presence of cavitated and noncavitated carious lesions in preschool children. The prevalence of children with noncavitated and cavitated carious lesions was 29.1% and 49.4%, respectively. Furthermore, poor oral hygiene is a potential risk indicator associated with noncavitated lesions, whilst poor oral hygiene and poor parental oral health knowledge and attitude are associated with the presence of cavitated lesions. Thus, the findings highlight the importance of effective toothbrushing and enhancement of parental oral health knowledge to support health behaviour change, thereby preventing the development of noncavitated and cavitated carious lesions.

Author contributions

Manchanda Sheetal worked on the conception and design of the study, data collection, analysis and interpretation, drafting the manuscript, and approval of the version to be published. Liu Pei worked on the conception of the study, data collection, analysis and interpretation, drafting the manuscript, and approval of the version to be published. Lee Gillian H.M. worked on the conception of the study, interpretation of the results, drafting the manuscript, and approval of the version to be published. Lo Edward C.M. worked on the conception of the study, interpretation of the results, drafting the manuscript, and approval of the version to be published. Yiu Cynthia K.Y. worked on worked on obtaining the research fund, conception of the study, interpretation of the results, drafting the manuscript, and approval of the version to be published.

Conflict of interest

None disclosed.