Factors Associated With Dental Caries in Primary Teeth of 5‐ and 6‐Year‐Old Polish Children

ABSTRACT

Background

Caries in primary teeth remain a common health issue.

Aim

To identify oral health behaviours which significantly affect dental caries in children aged 5–6 years.

Design

A national cross‐sectional study of 1892 children integrated dental examinations and a questionnaire regarding socio‐economic factors and oral health habits. Caries indices were calculated. The analyses included t‐ and chi‐square tests, Spearman's correlation, bivariate and multivariate logistic regression (p < 0.05).

Results

The majority of children (79.3%) had caries; mean dmft was 4.68 ± 4.05; dmfs—9.12 ± 10.74 and ft/ft. + dt—0.20 ± 0.31. There were correlations between mother's education, her knowledge of oral health, financial burden, the frequency of dental appointments and the treatment (p < 0.001). The dmft indices were correlated with postponing dental appointments and presenting with pain. The association between the treatment index, oral hygiene habits (parental‐supervised toothbrushing twice a day, using fluoridated toothpaste) and dietary practices (restrictions of sugar intake, fruit juices and starchy foodstuffs) was found, even after socio‐economic confounding factors were introduced.

Conclusion

The first years of a child's life are a period when the foundations of adult lifestyle choices are shaped. Parents should be aware of the importance of dental visits, nutritional counselling and proper oral care. The assessment of risk factors related to families is indispensable when prophylactic programmes are implemented.

Summary.

• Why this paper is important to pediatric dentists

  • ○The first years of a child's life are a period when the foundations of lifestyle choices are shaped.
  • ○The assessment of risk factors related to families is indispensable when prophylactic and therapeutic programmes are to be implemented.
  • ○It must be emphasised that parents/caregivers play the key role in shaping oral health‐oriented habits of children. It is recommended that they should be educated in the field of dental caries prevention and made aware of the role that foodstuffs containing not only simple sugars but also starch have in the aetiology of caries. It is necessary to update the guidelines by accentuating the need to limit the intake of sugar and starch.

1. Introduction

Caries in primary teeth remains a common health issue which affects more than 560 million children worldwide [1]. Its incidence is higher than that of other noncommunicable diseases (NCDs) [2]. In European countries, the prevalence of caries in preschool children appears to remain too high, not fulfilling the WHO objectives for 2020 [3, 4], with certain regions reporting alarmingly high rates. In Poland, it already afflicts 41.1% of children at the age of 3. Between the ages of 3 and 6, the frequency of the disease increases twofold [5].

Maintaining healthy primary dentition until it is lost is the prerequisite for proper masticatory functions and clear speech. It also gives the face its aesthetics and makes space for the permanent dentition. The presence of dental caries hampers adequate nutrition of the child, disrupts facial appearance and emotional development [1]. Children who experience decay in their primary dentition are also more likely to have it in their permanent teeth. Untreated, it may exert a negative impact on one's quality of life, growth and development. What is more, the disease causes pain, requires antibiotic therapy, sedatives, or general anaesthesia, as well as leads to a premature loss of teeth and malocclusions [1, 4].

Despite access to free dental care and preventative measures, preschool children in Poland reflect neglect in the area of prevention and therapy. The index values for treatment range from 0.07 in 3‐year olds to 0.26 in 6‐year olds [5]. It seems that the main cause of the inferior state of primary dentition is insufficient health awareness and parent's/caregiver's attitudes resulting in inappropriate health‐related habits. The preschool period is fundamentally formative for health‐oriented behaviours for the whole life, including oral health. Health education must involve both the parents/caregivers and their children, but it should focus on the identification of needs. It is a fact that inappropriate lifestyle choices that lead to excessive exposure to sugar, hygiene neglect and fluoridation omissions contribute to dental caries. The impact of these habits may differ in populations. In Poland, the fluoride content in water is insufficient (< 0.5 mg F/L), drinking water is not fluoridated and geographical position is partly responsible for vitamin D insufficiency [6].

The aims of the study were to identify oral health behaviours of children aged 5–6 years, indicate those which significantly give rise to caries and determine their impact. Education needs of caregivers were also discerned.

2. Materials and Methods

As part of the Ministry of Health programme ‘Monitoring of the oral health of the Polish population between 2016 and 2020’, a national cross‐sectional survey of children aged 5–6 years (2016 and 2018) was conducted. The study groups were selected in a three‐tier draw (district/community, urban/rural, kindergartens/primary schools). Inclusion criteria were as follows: participants at the age of 5 and 6, cooperation of the child, a written informed consent and correctly filled in questionnaire by parents/caregivers.

Data on the total number of children were retrieved from the Central Statistical Office (Demographic Yearbooks of Poland in 2015). The sample size was calculated based on figures found in literature concerning the prevalence of caries in this age group in Poland, that is, about 80.0% of the caries‐affected. With such assumptions, a 95% level of confidence and ±4% error tolerance, about 750 individuals in each group of participants represented a minimum sample size. One thousand 5‐year olds and an identical number of 6‐year olds were invited to participate in the study. Eventually, a total of 1892 children were examined, including 893 5‐year‐olds and 999 6‐year‐olds.

The examination consisted of the clinical evaluation plus a questionnaire with closed questions (yes/no/I don't know) on socio‐economic factors (place of residence, self‐assessment of expenditure on oral health care, education level, knowledge of oral health), oral hygiene habits (frequency of toothbrushing, parental‐supervised toothbrushing (PSB), the use of fluoridated toothpaste and other dentifrices), nutrition (frequency of consumption of specific foodstuffs) and accessing dental services.

In Poland, there is a five‐grade classification of education: basic/primary, vocational, secondary, post‐secondary and tertiary/master's degree education. The authors distinguished three categories: 1—primary and vocational, 2—secondary plus post‐secondary and 3—tertiary. The respondents did not specify their monthly income per household; therefore, the criterion of the economic status was accepted as based on the respondent's subjective feeling of the cost of oral health care. The questionnaire used in this study was the same one that has been utilised many times while monitoring the Polish population, in compliance with the WHO guidelines to ensure standardisation of data collection [7].

The assessment of dentition was performed by dental practitioners following training and calibration (Cohen's kappa coefficient between the reference researcher and the remaining researchers was in the range of 0.89–0.96). The examination was conducted in accordance with research standards and WHO classification [7]. The presence of teeth/dental surfaces with cavitated lesions (dt/DT; ds/DS), teeth and dental surfaces lost due to caries (mt/MT; ms/MS) and filled teeth (ft/FT; fs/FS) was noted [7]. Mean dmft/dmfs, DMFT/DMFS values were calculated. Also, the number and percentage of the study subjects with caries were determined (dmft/DMFT > 0) as well as the component of treatment of primary teeth (ft/ft. + dt).

In order to analyse the influence of health‐related behaviours on the condition of teeth, indices of dental health and the results of the questionnaire surveys for both age groups were calculated. The studied variables were presented in the form of percentages or means with standard deviation (SD). The comparison of means between the two groups was done with the t‐test, while the comparisons of percentages were done with the chi‐square test. To determine the relationship between pairs of variables, Spearman's correlation analysis was performed. In order to assess the impact of different factors on the prevalence of dental caries in children, a bivariate logistic regression analysis was conducted, in which the impact of each individual factor was considered as well as that of multivariate logistic regression, in which the simultaneous impact of several factors was assessed. Based on logistic regression, odds ratios (ORs) were defined for a relative risk of caries development, including confidence intervals (with a confidence level of 95%). An adjusted odds ratio (AOR) was calculated, with the socio‐economic factor as the confounding one. The analyses were conducted using SPSS 22 and Statistica 10 software and the R 3.2 software package.

3. Results

The final analysis covered the results obtained after examining 1892 children at the age of 5 and 6, including 963/50.9% males and 1101/58.2% urban dwellers. A number of children (108) did not participate for the following reasons: no consent of the parent/caregiver (41), absence at the kindergarten/school during the examination (54) and poor cooperation (13).

Mixed dentition was recorded in 1052 children, including 234 children at the age of 5 and 818 6‐year‐olds. The values of indices related to dental health of children are presented in Table 1.

TABLE 1.

Dental health of 5‐ and 6‐year‐olds.

Indices		The total sample	Five‐year‐olds	Six‐year‐olds
The number of primary teeth	Mean ± SD	18.58 ± 1.79	19.43 ± 1.19	17.81 ± 1.89
The number of permanent teeth		2.48 ± 2.77	0.81 ± 1.68	3.97 ± 2.71
dmft > 0	n/%	1501/79.3%	686/76.8%	815/81.6%
dmft	Mean ± SD	4.68 ± 4.05	4.70 ± 4.33	4.66 ± 3.77
DMFT		0.11 ± 0.51	0.03 ± 0.25	0.19 ± 0.65
dmfs		9.12 ± 10.74	9.32 ± 11.60	8.94 ± 9.91
ft/ft. + dt		0.20 ± 0.31	0.15 ± 0.28	0.25 ± 0.33

Table 2 presents the characteristics of the examined group, taking into account socio‐economic factors, health‐oriented behaviours and access to dental care services. Of the whole number of respondents, 249/13.2% intentionally did not use fluoridated toothpaste and 336/17.7% were unable to provide such an answer.

TABLE 2.

Socio‐economic factors and oral health behaviours of children at the age of 5 and 6.

Sociomedical factor	n/%
Mother's education status
Primary/vocational	62/3.3
Secondary	741/39.0
Tertiary—master's degree/bachelor's degree	1083/57.1
Self‐assessment of expenditure on oral health care
High	327/17.2
Moderate	1071/56.4
Small	494/26.0
Self‐assessed knowledge of oral health
Very good	212/11.2
Limited and sufficient (average/general)	1656/87.2
Insufficient/none	24/1.3
Correct answers
Children should regularly attend dental check‐ups	1842/97.0
Frequent snacking between main meals contributes to caries	1368/72.1
Overuse of sugar causes caries	1794/94.5
Children below the age of 7 and 8 should be supervised by adults while brushing teeth	1056/55.6
Fluoride‐containing products help protect teeth from caries	1535/80.9
Primary teeth do not require the same amount of care as the permanent ones do since they are going to fall out anyway	1548/81.6
Caries in primary teeth is transmitted onto permanent teeth	1183/62.3
Cariogenic bacteria may be transmitted to the child's mouth, for example from its mother	966/50.9
Oral hygiene habits
Brushing teeth at least twice a day	1274/67.1
Brushing teeth less frequently than once a day, sporadically, or never	124/6.5
Toothpaste with fluoride	1307/68.9
Flossing	166/8.7
Mouth rinsing	353/18.6
Adult brushes the child's teeth	384/20.3
Dietary behaviours
Sugar substitutes	659/34.7
Foodstuffs consumed several times a day or every day
Fresh fruit and vegetables	1293/68.1
Sponge, cakes, pastries, doughnuts, layer cakes, iced cakes	337/17.8
Jam/honey	146/7.7
Chewing gum with sugar	53/2.8
Chewing gum without sugar	72/3.8
Sweets/candies	255/13.4
Sugary beverages (cola and lemonade)	116/6.1
Tea with sugar	795/41.9
Fruit juices	584/30.8
Crisps, salted sticks, etc.	42/2.2
Parental restrictions concerning consumption of foodstuffs with sugar	1482/78.3
Verbally banning the consumption of foodstuffs with sugar on the spot	641/33.9
Rationing sweets	979/51.7
Accessing dental health care
Unattended appointment in the past 12 months	180/9.5
Unattended appointment in the past 2 years	35/1.8
Dental appointment prompted by toothache	254/13.4
Dental appointment prompted by a check‐up	718/37.8
Postponing dental appointments	213/11.2
Supervised toothbrushing at school/kindergarten	254/13.4

Spearman's analysis did not confirm any relationship between dental caries in primary teeth on one hand and rural or urban place of residence on the other hand (Table 3). The risk of the disease also decreased as the mother's level of education and her dental knowledge improved; it increased, however, with the recognition of the financial burden associated with dental health care. There were other positive correlations between mother's education, her knowledge of oral health and the frequency of dental appointments on one hand and the index value of the treatment (ft) on the other hand. Spearman's analysis indicated which health‐related behaviours were correlated with caries in primary teeth and the treatment of dental lesions (Table 3). Dental appointments were associated with the presence of caries necessitating medical attention. Positive correlations between the dmft/dmfs indices, postponing dental appointments and presenting with pain were also found. Attending dental check‐ups had a favourable effect on oral health. Benefits from dental visits were additionally evidenced by the relationship between the treatment of primary teeth index (ft) and good oral hygiene habits (toothbrushing at least twice a day, parental‐supervised toothbrushing (PSB), using prophylactic mouth rinses, fluoridated toothpaste) and diet (less frequent consumption of fruit juices). The analysis confirmed that toothbrushing twice a day with the assistance of a parent/caregiver, restrictions on sugar consumption and check‐up appointments significantly reduced the risk of caries even after socio‐economic factors as confounding factors were introduced (Table 4). Frequent consumption of sweets/salted starch‐rich foodstuffs and the avoidance of dental visits had a statistically significant effect by increasing the risk of the disease.

TABLE 3.

Statistically significant Spearman's rank correlation coefficients revealing the relationship between socio‐economic factors/health‐oriented behaviours and caries indices and/or conservative treatment of primary teeth ratio in children at the age of 5 and 6.

Factors	dmft > 0	dmft	dmfs	Treatment of primary teeth ratio
Gender (female)	−0.042	−0.054*	−0.050*	0.016
Mother's educational status	−0.080*	−0.139*	−0.155*	0.108*
Self‐assessed sense of expenditure related to oral health care	0.053*	0.073*	0.077*	0.080*
Self‐assessed knowledge of dental issues	−0.089*	−0.115*	−0.115*	0.068*
Researcher‐assessed knowledge of dental issues	−0.068*	−0.076*	−0.072*	0.124*
Frequency of dental appointments	0.179*	0.232*	0.224*	0.315*
Unattended appointment in the past 12 months	−0.086*	−0.108*	−0.104*	−0.228*
Dental appointment prompted by a check‐up	−0.125*	−0.181*	−0.185*	−0.018
Dental appointment prompted by toothache	0.130*	0.225*	0.247*	−0.018
Postponing a dental appointment	0.027	0.072*	0.077*	−0.071*
Brushing teeth at least twice a day	−0.117*	−0.125*	−0.115*	0.112*
Brushing teeth less frequently than once a day, sporadically, or not at all	0.057*	0.059*	0.052*	−0.050
Adult brushes child's teeth	−0.080*	−0.072*	−0.074*	0.033
Use of mouth rinses	0.029	−0.011	−0.006	0.060*
Frequency of consumption of foodstuffs
Sponge, cakes, pastries, doughnuts, layer cakes	0.073*	0.088*	0.092*	−0.012
Candies, bars, sweets	0.058*	0.071*	0.089*	−0.010
Fruit juices	0.091*	0.102*	0.108*	−0.109*
Sugar‐sweetened beverages	0.132*	0.158*	0.160*	−0.038
Tea with sugar	0.054*	0.076*	0.076*	−0.030
Salted starchy products (crisps)	0.093*	0.111*	0.110*	−0.048
Parental restrictions concerning consumption of foodstuffs with sugar	−0.084*	−0.116*	−0.117*	0.040
Verbally banning the consumption of foodstuffs with sugar on the spot	−0.069*	−0.060*	−0.058*	0.063*
Rationing sweets	−0.069*	−0.087*	−0.088*	0.034

*Statistical significance p < 0.05.

TABLE 4.

Simple (OR) and multiple (AOR) logistic regression analysis (socio‐economic factor as confounding factor for AOR).

Behaviour		dmft > 0			dmft	p
		n (%)	OR	AOR	Mean ± SD (95% CI)
Parental‐supervised toothbrushing at least twice a day (vs. sporadically and 1–3 times a week)	No	531/618 (85.9)	0.51 (0.40–0.67) p = 0.002*	0.54 (0.42–0.71) p ≤ 0.001*	5.37 ± 4.10 (5.04–5.69)	< 0.001*
	Yes	966/1274 (75.8)			4.34 ± 3.98 (4.06–4.62)
Adult brushes child's teeth	No	1218/1508 (80.77)	0.63 (0.49–0.98) p ≤ 0.001	0.59 (0.49–0.87) p ≤ 0.001*	4.81 ± 4.04 (4.54–5.08)	0.0371*
	Yes	279/384 (72.65)			4.15 ± 4.02 (3.85–4.45)
Dental appointment prompted by a check‐up	No	855/1020 (83.82)	0.54 (0.43–0.67) p ≤ 0.001*	0.51 (0.39–0.62) p ≤ 0.001*	5.34 ± 4.13 (5.06–5.62)	< 0.001*
	Yes	642/872 (73.62)			3.91 ± 3.81 (3.62–4.19)
Dental care avoidance	No	1322/1679 (78.74)	1.24 (1.01–2.34) p = 0.018*	1.26 (1.10–1.67) p ≤ 0.001*	4.57 ± 3.99 (4.33–4.81)	< 0.001*
	Yes	175/213 (80.75)			5.57 ± 4.35 (5.19–5.95)
Restricting consumption of foodstuffs with sugar	No	351/410 (85.6)	0.57 (0.42–0.77) p = 0.030*	0.61 (0.45–0.83) p = 0.001*	5.51 ± 4.04 (5.10–5.91)	< 0.001*
	Yes	1146/1482 (77.3)			4.45 ± 4.02 (4.10–4.80)
Fruit juices—daily or several times a day	No	1007/1308 (77.0)	1.56 (1.21–2.01) p = 0.002*	1.52 (1.17–1.96) p = 0.001*	4.42 ± 3.95 (4.14–4.70)	< 0.001*
	Yes	490/584 (83.9)			5.25 ± 4.20 (4.95–5.55)
Sugar‐sweetened beverages consumed daily or several times a day	No	1391/1776 (78.3)	2.93 (1.52–5.67) p = 0.006*	2.61 (1.34–5.06) p = 0.005*	4.58 ± 4.03 (4.34–4.81)	< 0.001*
	Yes	106/116 (91.4)			6.16 ± 4.06 (5.84–6.48)
Salted starchy products (crisps) consumed daily or several times a day	No	1461/1850 (79.0)	1.60 (0.67–3.82) p = 0.178	1.38 (0.58–3.33) p = 0.468	4.64 ± 4.02 (4.40–4.88)	0.003*
	Yes	36/42 (85.7)			6.50 ± 4.75 (6.06–6.94)

Abbreviations: AOR, adjusted odds ratio; OR, odds ratio.

*Statistical significance p < 0.05.

4. Discussion

The present study focuses on the analysis of oral health status and behaviours of children aged 5–6 years in Poland by gathering necessary data to attain the goals set by the World Dental Vision Fédération Dentaire Internationale (FDI) to be fulfilled by the year 2030, including 50% of caries‐free 6‐year‐olds [8]. Alliance for a Cavity Free Future (ACFF) working group concluded that education and behaviours had to bring about change in the scope of caries prevention [4].

Despite the fact that research on dental caries has been conducted since the 1950s, the results obtained in our study, as well as in those done by many other authors, indicate that the prevalence of the disease is still high. Consequently, there seems to be the need to investigate the link between dental caries in children and their oral health habits [9]. The preschool period is a window for behavioural intervention since it is the time when shaping children's habits becomes reinforced with a greater willingness of parents/caregivers to follow health recommendations [3, 9]. The outcome of this study also illustrates the parents'/caregivers' knowledge and their attitudes to oral health. Even though it is generally positive, only half of the respondents understood that caries in primary teeth is a risk factor for decay in the permanent teeth and knew that a child at the preschool age should have their teeth brushed by an adult.

Almost every respondent understood that a child should attend dental check‐ups, and yet every tenth child missed appointments in the last year. According to the latest data coming from the Monitoring of Oral Health, approximately 10%–13% of Polish 5‐year‐olds have never seen a dentist, and one in four has a dental appointment once a year [5].

The previous research reported that the most common reason (60%) for the first dental visit of children from Warsaw was a check‐up [10]. In the current study, the proportion of children in Poland was half lower, and appointments were associated with the pain and/or the presence of caries necessitating treatment. Positive correlations between the dmft/dmfs indices and postponing dental appointments were also found. Adugna et al. [11] established a significant association between dental caries and a history of dental visits. Children who had dental caries were three times more likely to have visited the dentist at least once than to have never visited [11].

The beneficial effect of dental visits is an opportunity for direct education and preventative procedures. Dentists should communicate their recommendations effectively so that parents/caregivers/patients can perceive them as behaviours worth pursuing. Motivational interviewing (MI) and self‐determination theory are examples of effective encouragement strategies [12].

The present analysis reveals a positive relationship between treatment index, toothbrushing twice a day, PSB (especially with fluoridated toothpaste), using prophylactic mouth rinses, and the lower risk of caries. Toothbrushing twice a day appears to be the basic method of preventing caries, but only 67.1% of children in this study complied with this rule. Hygienic neglect in children aged 5 and 6 years was reported by other authors [13]. The preschool children in China who brushed their teeth twice daily had a 76% lower risk of caries in comparison with those who did not brush their teeth every day [14]. The number of children who brushed their teeth twice a day also increased significantly along with the increased effectiveness of PSB [12]. According to the core elements of the Health Action Process Approach (HAPA), parents/caregivers are expected to assist/supervise their children when they brush teeth with fluoridated toothpaste [15]. If parents/caregivers care for the oral health of their children and offer PSB twice daily as well as motivate them to do the activity, the risk of caries may decrease [2, 12, 16, 17, 18, 19, 20]. PSB could result in a 15% reduction of dental caries, and, if commenced before a child is 1 year old, it may double the chance of having caries‐free teeth at preschool age [17]. Other findings also indicated that children who did not brush their teeth under supervision were three times more likely to develop dental caries as compared with children who brushed their teeth under their parents'/caregivers' supervision [11]. PSB may habituate children to the daily use of fluoridated toothpaste. In our investigation, the parents/caregivers were aware of the benefits of using fluoride; however, not all of them used such toothpaste.

The use of dental floss was rather uncommon among preschoolers in our study. Although our analysis has revealed that caries was not related to the absence of dental flossing, which corroborates the findings in other studies, it is worth highlighting that parents/caregivers of young children ought to floss their deciduous teeth [21]. The findings in Vernon et al. [22] showed that flossing children's teeth was associated with a 40% reduction in the risk of caries.

The studies reported a significant association between sugary foods and dental caries [20]. In addition to this well‐known risk, our study highlights the link between the disease and the consumption of fruit juices and starchy foods. Less frequent ingestion of sweets/salted starch‐rich foodstuffs and fruit juices as well as restrictions on sugar intake significantly reduce the risk of caries even after socio‐economic factors as confounding factors were introduced. This has implications for oral health promotion practices. Parents'/caregivers' knowledge can also help predict behaviours related to the control of their children's consumption of sugary and starchy foods. All the same, children in Poland consume the highest amount of sugar in Europe (95 g/day) [6]. According to WHO, the sugar content in children's diets should not exceed 10% of the daily energy requirement (50 g/day) or it ought to be even below 5% [23].

Almost all of the respondents knew that excessive sugar intake leads to caries, but only three quarters decided to restrict its consumption, for example in the form of verbal interventions. In our study, children who had restrictions placed on their sugar consumption had lower dmft. Reducing sugar intake without lowering the exposure to this substance on a regular basis is ineffective in preventing dental caries [24]. It is of utmost importance to limit children's sugar intake in order to minimise the lifetime risk of caries [20]. Studies that underline the primary role of exposure to sugar in the aetiology of caries reveal that toothbrushing with fluoridated toothpaste only slightly diminishes the adverse impact of frequent, long‐term exposure to sugar and frequent snacking by children below the age of 5 years [16, 25].

The results of numerous studies demonstrate a positive association between the consumption of Sugar‐Sweetened Beverages (SSBs), fruit juices, foodstuffs rich in free sugars or starch and dental caries [16, 18, 20, 21, 26, 27, 28]. SSBs increase the risk of caries three times, whereas juices—1.5 times [16]. A third of our respondents provide their children with juices every day, and some let them have SSBs. Studies find that parents/caregivers believe that sugary fruit juices are healthy [29].

Starchy foods are considered to have a high cariogenic potential [18, 21, 26, 27, 28]. The total time during which the pH of dental plaque remains below the critical level of 5.5 after exposure to processed sugary and starchy food is significantly higher compared to food containing high concentrations of sucrose only. Therefore, the intake of starch has a cariogenic effect, which combines with the negative influence of other sugars. Foodstuffs with relatively low contents of sugar which, however, are high in starch are linked to the increased risk of dental caries [28]. Although the parents/caregivers have considerable knowledge of the impact of sugar on caries development, it appears that they are not aware of the detrimental dental consequence of starch. Such findings indicate the need for parental education. They should be made aware that starch, just like sugars in sweets and soft drinks, is cariogenic. Studies revealed that the awareness of the role of sugar in caries aetiology is a predictor for parents'/caregivers' intention and actual control over their child's sugar consumption. Nevertheless, tiredness, forgetfulness or a child's resistance often hinder their intentions [30].

The study presented in this paper has both strengths and limitations that are worth discussing. One of the strengths is the fact that it is the only piece of research to assess socio‐behavioural factors that may impact caries in primary teeth of Polish children. Another strong point is the large size of the representative population at high risk of caries, and the homogenous social structure without cultural or ethnic variations. One more advantage is the utilisation of both a questionnaire and clinical examination to assess caries. The objective evidence obtained by a trained, calibrated paedodontist translates into a smaller measurement error and, consequently, a lower risk of bias than one would expect from a study in which details about oral health are self‐reported by participants. To investigate the factors related to the prevalence of caries in children at the age of 5 and 6, multivariate logistic regression analysis was used, which constitutes another strength of this study. Such an approach makes it possible to assess the independent influence of various factors with a simultaneous control of the impact of other variables. Moreover, since caries is a multicausal condition, the study did not account for all the factors; instead, it focused on those which are significantly related. Obviously, the research was cross‐sectional and—for this reason—has a relatively low validation to draw conclusions concerning the causal association; it can be, however, used to derive insights about the relationship. This study makes no mention of other important confounding factors which could distort the results.

The study made use of the WHO criteria commonly used in epidemiological studies. Therefore, only cavitated carious lesions were recorded. In this analysis, the assessment of dental caries was done on the basis of the total dmft/dmfs indices, and not individual stages. Caries progression cannot be assessed with these indices, which may hinder the provision of a proper treatment plan in the population. In accordance with WHO guidelines, radiographs were not used for caries detection as it is not recommended to employ them to detect caries on interproximal surfaces in this kind of research. Fiberoptic transillumination (FOTI) was not utilised for the same reason [7]. Even though it is recognised that the abovementioned diagnostic methods help avoid underestimation of dental caries, logistical challenges and parents'/caregivers' objections to exposing children to radiation outweigh the potential benefits. One can expect, then, that this study underestimated the presence of interproximal caries, which develops after the primary molar contacts close around the age of 4. The 5‐ and 6‐year olds from this study may have significant undiagnosed interproximal lesions.

In the future, prospective longitudinal studies should be conducted to categorically confirm the positive relationship found in this investigation. Another limitation is over‐reporting. Paedodontists convey instruction to parents/caregivers; thereby, they are aware of oral health‐oriented behaviours. There is a potential risk of bias in answers to the questionnaire, which is a well‐known limitation of the value of parental reporting.

In summary, the findings of this study highlight the strong relationship between dental caries in Polish preschool children aged 5 and 6 years and the education of the mother, her oral health knowledge, postponing dental appointments, presenting with pain, PSB with fluoridated toothpaste twice daily, as well as a diet high in sugar, refined starch and fruit juices. These findings support the arguments for restricting access to such types of food and beverages, which could result in the improvement of children's oral health. Therefore, dental caries prevention should be the priority. It can become an opportunity to reverse negative epidemiological trends that are observed in Central and Eastern Europe, including Poland.

Author Contributions

D.O.‐K. had primary responsibility for protocol development, patient screening, enrolment, outcome assessment, supervision of the design and execution of the study, performing of the final data analyses and writing the manuscript. M.S. participated in the development of the protocol and analytical framework of the study, performed the final data analyses and contributed to the writing of the manuscript. A.T.‐S. had primary responsibility for protocol development, patient screening, enrolment, outcome assessment, preliminary data analysis and writing the manuscript. All the authors approved the final version of the manuscript.

Ethics Statement

The research has been conducted in full accordance with ethical principles, and including the World Medical Association Declaration of Helsinki (version, 2008). The study protocol was reviewed and ethical clearance had been obtained before the study began. The Bioethics Committee of the Medical University of Warsaw authorised the present study (Nos KB/190/2016 and KB/185/2018).

Consent

Informed written consent was obtained from all the children's parents or guardians participating in the study, in accordance with the World Medical Association's Declaration of Helsinki.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.