Childhood Caries Research Articles

Development of a Dental and Oral Health Education Model with an Authoritative Parenting Approach to Prevent Dental Caries in Early Childhood

Development of a Dental and Oral Health Education Model with an Authoritative Parenting Approach to Prevent Dental Caries in Early Childhood

Overweight/obesity and dental caries in Brazilian children and adolescents: a systematic review and meta-analysis.

This review aimed to assess the association between overweight/obesity and dental caries in Brazilian children/adolescents. Searches were performed in the Web of Science, Scopus, Cochrane, PubMed, Embase and SciELO, Lilacs and Open Grey literature databases up to June 2022. The Joanna Briggs Institute checklist for analytical cross-sectional studies, the checklist for cohort studies, and the checklist for case-control studies were used. A total of 41 publications were included, and 15 meta-analyses were performed. The authors analyzed the differences in weighted mean difference (MD) and odds ratios (OR), and their corresponding confidence intervals (CI) (95%) for dental caries among eutrophic and obese and/or overweight children/adolescents. Meta-analyses showed that there was no association between overweight and/or obesity and dental caries in Brazilian children/adolescents for most anthropometric reference curves using BMI (Body Mass Index). A greater experience of dental caries was associated with well-nourished adolescents in permanent dentition, compared with obese individuals in the same dentition, as classified by the CDC 2000 curve (OR = 2.53, 95% CI;1.49-4.29; p = 0.0006; I2 = 0%) in dichotomous outcome studies, and (MD = 0.61, 95%CI: 0.08-1.15; p = 0.02; I2 = 0%) in continuous studies. The strength of the evidence of the results was classified as very low, low or moderate. It was concluded that there is no association between overweight and/or obesity and dental caries in Brazilian children/adolescents for most anthropometric reference curves using BMI. A greater experience of dental caries was associated with well-nourished adolescents in permanent dentition, compared with obese individuals in the same dentition, as classified by the CDC 2000 curve.

Dental problems in children with autism: a 5-year study.

Caries experience of children and complex clinical circumstances are an actual challenge for any healthcare professional. To investigate the early childhood caries (ECC) in autistic and non autistic children (≤4 years of age) evaluating the amount of dental damage and the treatments carried out in both groups. Data regarding the oral health status of 40 patients (≤4 years of age) were assembled. The sample group was constituted of 20 autistic children (12 males with a mean age of 2.5 years and 8 females with a mean age of 3.2 years) whereas 20 patients without the autistic spectrum represented the control group (11 males with a mean age of 3 and 9 females with a mean age of 3.3 years). There were no significant differences between the two groups as regards both the extent of dental damage and the treatments carried out. About the frequency, in the autistic group, the most frequent caries were the white spots and enamel proximal lesions (2.2%), followed by only white spots (1.2%) and brown-black cavities and root stumps (0.6%). In the control group, the brown-black cavities and root stumps represented the most frequent findings (2.2%), followed by white spots and enamel proximal lesions (1.4%) and white spots (0.4%). Regarding the treatments, the most repeated management of dental damage among autistic patients was composite restorations (2.2%) while in nonautistic patients were tooth extractions (2%).

Efficacy and Safety of Probiotics for Dental Caries in Preschool Children: A Systematic Review and Meta-analysis.

Early childhood caries is one of the most serious and high-priced oral health conditions among young children. With advancing dental sciences, the focus of dental caries treatment is shifted from restorative procedures to preventive measures, and a modality grabbing attention is probiotics. Probiotics exert their effects in many ways as chemical inhibition of pathogenic bacteria and stimulation of the immune response through the production of immunoglobulin A and many more. This systematic review aims to explore the efficacy and safety of probiotics in dental caries in preschool children. The study was registered in the PROSPERO International Prospective Register of Systematic Reviews (registration number: CRD42020159058). The search was done for randomized control trials in electronic databases such as Cochrane, PubMed, ClinicalTrials.gov, Medline, and Embase. It has further included manual searches of journals, conference abstracts, and books. Three reviewers done the selection of the study as per the criteria and also did the risk of bias assessment independently and wherever required, a fourth reviewer resolved the discrepancy in case of disagreement. The nine randomized control trials were included in the study, and the pooled analysis revealed probiotics as an effective intervention in preschool children with dental caries. The results about the efficacy of probiotics in the prevention of dental caries are very encouraging, though the level of evidence is still inadequate.

Trends and age-period-cohort effect on dental caries prevalence from 2008 to 2019 among Brazilian preschoolers.

This study aimed to evaluate trends in the prevalence of dental caries in preschool children and associated factors considering different time variations. This is a time series study performed using data from three cross-sectional studies with pre-school children from southern Brazil in 2008, 2013 and 2019. This children group was born between the years of 2003 to 2018. Dental caries was evaluated by decayed, missing and filled deciduous teeth (dmft index). Demographic, socioeconomic, behavioural and psychosocial variables were also collected. Chi-square test for trends and a hierarchical age-period-cohort (HAPC) analysis using multilevel Poisson regression model for testing the associations between predictor variables and dental caries experience were used. A total of 1,644 pre-school children participated in all surveys. There was a significant difference in caries experience considering all APC effects. The prevalence of dental caries was 25.0% in 2008, 16.3% in 2013, and 19.4% in 2019 (p < 0.01) and no statistical difference was observed. An age effect showed that older children were more likely to experience dental caries. Considering the cohort effect, there is a significant difference between the generations, mainly between 2003 and 2018. Household income, use of dental services, and parent's perception of child oral health were associated with dental caries experience no matter the time variation. Despite recent declines in dental caries prevalence among preschool children, caries levels increased with age and social inequalities persisted through the years, indicating a need of reviewing the policies to reduce the burden of this oral disease.

Knowledge, Attitude and Barriers to Dental Treatment of Mothers Regarding Early Childhood Caries: A Cross-sectional Survey from Taif Province, Saudi Arabia

Introduction: “Early Childhood Caries (ECC), also called ‘baby bottle tooth decay’ or ‘early childhood tooth decay,’ significantly affects infants and children aged six or younger, causing cavities and with lasting impacts on oral health and overall well-being. Its global prevalence concerns healthcare professionals and policymakers due to its multifactorial nature, influenced by diet, oral hygiene, socio-economic factors, and maternal awareness. Mothers, as primary caregivers during early childhood, play a crucial role in ECC prevention and early intervention. Aim: This study examines mothers’ knowledge and attitude regarding ECC and risk factors associated with children’s dental health, to determine difficulties in dental therapy in Taif, Saudi Arabia. Materials and Methods: Using a cross-sectional survey design in the province of Taif, Saudi Arabia, a random sample of 288 mothers of healthy children aged three to seven years were surveyed. A structured questionnaire containing 26 close ended questions was used to gather information regarding the socio-demographic characteristics, knowledge and attitude of the mothers regarding ECC, as well as barriers to dental care. The questionnaire was originally drafted in English and then translated into Arabic by a professional translator. Using Statistical Package for Social Sciences (SPSS) software, an analysis and a representation of data was performed. Results: More than half of the mothers 57.63% (n=166) understood the relation between poor dental health and hygiene and a child’s ability to learn, and 20.13% (n=58) didn’t know if poor dental health can impair a child’s ability to learn (p=0.02). The notion that a visit to the dentist should begin within six months of the appearance of milk teeth was agreed with by 55.55% (n=160) of the mothers, while 28.81% (n=83) of them didn’t know the proper time for a child’s first visit to the dentist (p=0.03). Only 22.22% of the mothers didn’t know what the nearest dental center to them was. Conclusion: The present study revealed that mothers did have awareness of different aspects of oral health and dental caries, several mothers exhibited unfavorable attitudes toward oral health practices, which could set a negative example for their children.

Effects of Clearfil SE Bond 2 on restoring deciduous anterior teeth with ring caries and analysis of caries risk factors in children aged 3-8 years.

To investigate the impact of various self-acid corrosion adhesives in restoring ring caries in anterior deciduous teeth and the influencing factors of childhood caries. This study retrospectively analyzed the repair effect of two kinds of restoration schemes on the annular caries of children's deciduous anterior teeth. According to the repair scheme, 54 children with caries were divided into two groups. The children with 3M single bond repair were set as the control group, and the children with Clearfil SE Bond 2 repair were set as the study group. The repair effect of 6 months and 12 months of treatment and the treatment satisfaction of children were compared. Additionally, 50 children with no oral abnormalities were included as a healthy control group to analyze dental caries risk factors comparatively. The retention of dental restorations, marginal adaptation to dentin, and dental pulp vitality scores in the study group were significantly lower than those in the control group at both 6 and 12 months post-treatment, with statistically significant differences (p < 0.05). Moreover, satisfaction levels in the study group notably exceeded those in the control group (92.59% vs. 70.37%). Fisher exact test yielded a p value of 0.041. Binary logistic regression analysis revealed that daily tooth brushing habits and parental supervision were protective against dental caries occurrence. Conversely, plaque, dental calculus, proficiency in tooth brushing techniques, and post-brushing bedtime snacking emerged as independent risk factors for dental caries (p < 0.05). Compared to the conventional self-etching dentin adhesive filling regimen, the novel blended adhesive and composite resin filling significantly enhanced dental caries restoration outcomes and increased children's satisfaction. Notably, this approach was well-received by both children and their families. Further proactive measures targeting children with identified risk factors are warranted to reduce the incidence of dental caries.

The relationship between caries risk assessment using the CAT-AAPD method and the incidence of caries in children

The relationship between caries risk assessment using the CAT-AAPD method and the incidence of caries in children

Dental And Oral Health Counseling Efforts On Students' Knowledge Levels (SDN 02 Tiron Madiun)

Dental and oral health is an integral part of body health. To achieve optimal dental and oral health, periodic treatment must be carried out. At SDN 02 Tiron Madiun, there has never been any socialization about oral and dental health. The purpose of this study is to analyze dental and oral health extension efforts on students' level of knowledge. The research method used is quasi-experimental with a research design of one group pretest posttest design. The study was conducted at SDN 02 Tiron Madiun with 22 respondents. The Wilcoxon signed rank test is used to analyze the data. Based on the data obtained, it shows that 22 respondents have a level of knowledge with a good category, 21 people (95.5%) and this study shows the influence of dental and oral health counseling on students' knowledge level (p = 0.021). Intervention in the form of counseling with poster media can significantly increase student knowledge. Provision of knowledge and teaching about dental and oral health from an early age to reduce the incidence of dental caries in school-age children.

Nutritional habits as risk factors for dental caries in children from rural and urban areas in Skopje

Proper nutrition is a long-term investment in one’s own health. Oral health as an integral part of general health is in bidirectional relationship with diet and nutrition. Globalization and urbanization have led to nutrition transition from a traditional agriculturally-based diet to consumption of processed foods that are high in sugar. Children have been particularly affected by this change. The aim of this study was to investigate the association between specific nutritional and hygiene habits and the development of caries in children from urban and rural areas. The study was conducted in December 2019 and comprised children aged 6 years. A survey was made and children’s dental status was tested. The results obtained showed a higher percentage of healthy deciduous (50%) and permanent (35%) teeth in children from rural areas than in children from urban area. Both groups had similar habits in terms of cariogenic and cariostatic food intake, but there were differences in children's hygiene habits.

Nutritional Status and Caries at Children in Tajinan Sub-District Malang District

Background: Caries is a multifactorial disease that can happen to all ages, caries and malnutrition are problems that often happens to children and can affect general health. Caries can be related to malnutrition. Caries can make the child uncomfortable and lower the child’s appetite, thus leading to the decrease of nutritional intake which can make the child’s tooth more susceptible to caries and make the existing caries more severe, then it’s back to the beginning where the worsened caries will make the child’s appetite worse and so on. Objectives: To know the relations between caries and nutritional status at children in Tajinan sub-district Malang district. Methods: 80 elementary students were selected from two elementary school at Tajinan sub-District Malang District. Then the nutritional status is measures by anthropometric, using the body mass index for age (IMT/U) and Z-score and the level of caries is measured by using DMF-T and def-t index. Conclusion: There is an inverse relationship between the two variables (nutritional status and caries) in children, which means the lower the child’s nutritional status the higher the caries is and vice versa. The Spearman significancy is p=0,012 (P&lt;0,05). Conclusion: There is a relationship between nutritional status and caries.

Factores asociados a la caries en infancia temprana

Introduction: Caries in early childhood is very common since there are different risk factors such as diet that are possible contributors to the appearance of dental caries in childhood. Design: A systematic review of studies that were evaluated was carried out, which were published between 2015 and 2021. Data sources: A search was performed through PubMed. The eligibility criteria were articles that used: diagnostic criteria for carious teeth, with indication of extracted and filled (ceo-d) criteria used by the World Health Organization (WHO) with calibrated examiners, probabilistic sampling and sample sizes. Study selection: Five previously calibrated reviewers searched, chose and extracted information from the chosen articles. All analyzes together were based on random effects models. Results: 14 articles were included. Some studies indicate that age becomes a risk factor for preschool children to have childhood cavities, which requires more constant tooth brushing and a greater Area Under the Curve (AUC) composed of the daily frequency. consumption of juices could be associated with dental cavities. Conclusions: Early childhood caries (ECC) is a dental disease caused by many factors that affects the primary teeth of children under 6 years of age. This is a very common disease in childhood and can have a negative impact on the well-being of children, while others indicate that breastfeeding is associated with a higher risk of ECC and may also be associated with a lower risk of ECC.

Experience, Prevalence, and Severity of Dental Caries in Mexican Preschool and School-Aged Children.

Objective Dental caries in Mexico continues to be a public health problem, indicated by it is high prevalence and incidence in children. This disease is associated with pain in preschool and school children, with large-scale consequences for the individual, society, and health systems. The objective of the present study was to determine the experience (mean of caries indices), prevalence, and severity of caries in children 2-12 years of age who sought dental care at a dental school in Mexico. Material and methods A cross-sectional study was carried out on 826 clinical records of patients ages 2-12 years. The dependent variable was caries, in terms of experience (mean primary teeth (dmft) and permanent teeth (DMFT) indices), prevalence (dmft and DMFT greater than 0), and severity (cutoffs of caries indices at various levels). The independent variables were age and sex. The data were analyzed in Stata 14 (StataCorp LLC, College Station, Texas). Results The average age was 7.2±2.3; 52.4% were boys. In the primary dentition, the caries experience (mean dmft) was 3.01±3.30, the prevalence of caries was 65.8%, and the severity dmft>3=37.3% and dmft>6=15.6%. In the permanent dentition, the caries experience (mean DMFT) was 0.99±1.88, the prevalence of caries was 31.5%, and the severity DMFT>3=12.5% ​​and DMFT>6=1.6%. The percentage of caries-free children in both dentitions was 26.1% (n=216/826). The experience, prevalence, and severity of caries were statistically different by age (p<0.001). Only in the severity of dmft>3 were differences observed across sex (p<0.05). Among children with mixed dentition, primary teeth were more affected than permanent teeth (2.46±2.87 vs 0.88±1.61; p<0.0001). Conclusions About seven out of 10 children were affected by cavities in either or both dentitions. It was observed that age was positively associated with dental caries, equally affecting girls and boys. In this sample, the primary dentition was impacted more than the permanent dentition. Despite being preventable, dental caries continues to be a health problem in children.

Association between Candida albicans and childhood dental caries in Japanese children

IntroductionThe possible association between Candida carriage in children and childhood caries has not been elucidated in the Japanese population. This study aimed to investigate the prevalence, maternal relatedness, and genotypic distribution of Candida albicans in this population. Materials and methodsWe collected dental plaque samples from 55 mother-child pairs in the Caries group and 25 pairs in the caries-free (CF) group to analyze microbial data (carriage and viable counts), focusing on Streptococcus mutans and C. albicans. Clinically isolated 118 Candida strains were further evaluated using arbitrarily primed polymerase chain reaction. ResultsA higher C. albicans carriage rate was observed in the Caries pairs (25.5 % in children, 47.3 % in mothers) than in CF pairs (0 % in children, 24.0 % in mothers). The viable counts of S. mutans were significantly higher in the Caries group than in the CF group (p < 0.05). In addition, S. mutans counts positively correlated with C. albicans counts in the dental plaque of caries-affected children (r = 0.549). Almost all Candida-positive children (92.9 %) were diagnosed with severe early childhood caries, and 79.7 % of Candida isolates from the mother-child pairs were similar at the strain level. C. albicans genotype A was the most predominant (70.6 %) strain, followed by genotype D (17.6 %) in dental plaques from children in the Caries group. ConclusionsThe presence of C. albicans is a risk factor for childhood caries in a Japanese population. Our findings provide new insights into maternal-child oral health instructions based on microbial factors associated with dental caries.

Silver Diamine Fluoride Renaissance in Paediatric Dentistry: A 24-Month Retrospective and Cross-Sectional Analysis.

Background and Objectives: Silver diamine fluoride (SDF) has been incorporated into the treatment of dental caries in children, mainly in countries with high caries prevalence. In Europe, however, SDF started to gain popularity during the COVID-19 pandemic. This study aimed to investigate the efficacy of SDF and to evaluate dentists'/parents' acceptance of SDF use in paediatric patients treated in a German university setting. Materials and Methods: A retrospective analysis of all patients treated with SDF between 2017 and 2020 was carried out. Only teeth with no reported clinical/radiographic evidence of irreversible pulpal inflammation were included. The outcome measures were success, minor failures (caries progression, reversible pulpitis) and major failures (irreversible pulpitis, abscess). The treatment acceptance by dentists and the parents of SDF-treated children was cross-sectionally evaluated using questionnaires. Descriptive statistics and Kaplan-Meier survival analysis were performed. Results: A total of 93 patients (mean age 5.3 ± 2.9 years) with 455 treated teeth (418 primary/91.9%; 37 permanent/8.1%) were included and followed up for up to 24 months (19.9 ± 10.5 months). SDF was used for dental caries (98.2%) and hypersensitivity relief on MIH teeth (1.8%). Most teeth did not show any failure (total success 84.2%). A total of 5 teeth (1.1%) showed minor failures, and 67 teeth (14.7%) showed major failures (p = 0.001). Success/failure rates were not affected by patient compliance, gender, dentition, or operator (p > 0.05). In total, 30 questionnaires were collected from parents (mean age 36.8 ± 6.4 years). SDF was applied on anterior (n = 2/6.7%), posterior (n = 15/50%) and anterior/posterior teeth (n = 13/43.3%). At the 1-week follow-up, 80% of parents noticed black teeth discoloration. Treatment satisfaction was higher for posterior (95.2%) than for anterior teeth (36.4%; p < 0.001). In the 27 responses from clinicians, SDF was generally considered a viable option in paediatric dentistry (n = 23; 85%). Conclusions: SDF was found to be effective and well-accepted by parents and dentists for caries inactivation in a paediatric dentistry German university setting.

Physicomechanical Properties of Resin-Based Pit and Fissure Sealants Reinforced with Rice Husk Derived Nano Silica and Nanohydroxyapatite

Resin-based pit fissure sealants (RBS) are used to prevent occlusal caries in children. The success of RBS in preventing dental caries is largely influenced by its retention on the tooth surface, which is also affected by its physicomechanical properties. The physicomechanical properties of RBS can be enhanced through the addition of fillers. With the advent of nanofillers, the physicomechanical properties were improved without altering RBS flowability. The present study developed an RBS with a 70 wt% resin matrix and 30 wt% nanofillers. The resin matrix consisted of urethane dimethacrylate (55 wt%), triethylene glycol dimethacrylate (45 wt%), camphoroquinone (0.3 wt%), and 2-(dimethylamino) ethyl methacrylate (0.7 wt%). Silane-treated rice husk-derived nanosilica (20 wt%) and nanohydroxyapatite (10 wt%) were added as fillers. Clinpro, Fissurit FX, and an unfilled sealant were controls. All RBS were tested for surface roughness, Vickers hardness, flexural strength, and flowability. Statistical analysis with oneway ANOVA revealed significant differences between groups in surface roughness, hardness, flowability (p &lt; 0.001), flexural strength, and flexural modulus (p &lt; 0.05). Experimental sealants had higher flexural strength (78 MPa) and flow distance (29.05+1.16 mm) than commercial controls. However, the surface roughness of experimental sealants (0.25+0.08 µm) was higher than Clinpro (0.087+0.027 µm) but lesser than Fissurit FX (0.35+0.19 µm). The Vickers hardness of experimental sealants (23+1.63 VHN) was less than Fissurit FX (28.80+1.69 VHN) but higher than Clinpro (21.74+1.68 VHN). This novel RBS had physicomechanical properties comparable to commercial sealants. The use of nanosilica from rice husk makes this pit and fissure sealer sustainable and environmentally friendly in dentistry.

Review on risk factors associated with childhood caries

Caries, also known as tooth decay or worm's tooth, is a disease of the oral cavity caused by multiple factors. It is one of the most common diseases of humans worldwide, and the World Health Organization (WHO) has identified it as one of "three major diseases affecting human health" along with tumors and cardiovascular disease. Genetics, the environment, and microorganisms all play a role in the development of its diseases. Caries is the leading cause of tooth loss in children, with a prevalence that is five times higher than that of asthma. It lowers adult life quality by causing pain in the teeth, spoiling their appearance, and making it difficult to replace missing teeth. Preventing and controlling a condition like childhood caries requires an understanding of the elements that contribute to it. This research will conduct a systematic literature review to examine the potential causes of caries in younger children.

Clinical Correlation of Vitamin D Deficiency and Early Childhood Caries: A Cross-Sectional Study in Western Rajasthan.

To ascertain whether a link exists between vitamin D insufficiency and early childhood caries or not. From the out patient department (OPD) of the Pedodontics Department at Vyas Dental College, a random sample of 40 kids between the ages of 8 months and 5 years old was chosen. Each kid had blood drawn to check their serum 25(OH) vitamin D levels. All of the data was collated and given the necessary statistical analysis. The case group's mean serum 25(OH) vitamin D level was 10.19 ng/mL (with a standard deviation of 3.46), while the control group's was 20.84 ng/mL (2.54 SD). A significant modifiable risk factor for childhood dental caries is a vitamin D deficiency. Therefore, cavities in teeth can be avoided by giving youngsters vitamin D supplements and avoiding vitamin D insufficiency.

Relation Of Habitual Of Brushing Teeth With Candida sp. Colony Count in Children Dental Caries Under 10 Years Old

The dental and oral disease problem faced by the Indonesian population as well as in other developing countries is dental caries tissue disease. Bacteria colonize the oral cavity to produce acid, resulting in a demineralization process in dental caries tissue. Candida albicans is the main agent of oral candidiasis. The development of these two microorganisms interacts with each other to form a layer of biofilm, which is the beginning of caries. Candidiasis is a fungal infection caused by Candida sp., which is the normal microflora in the oral cavity. This study aims to analyze the relationship between tooth brushing habits and the number of Candida sp. in dental caries in children under 10 years of age. This research is an analytic survey with a cross-sectional approach. Based on research on the relationship between brushing teeth and the number of Candida sp. in children under 10 years of age at SDN 01 Petung Bondowoso students, it can be seen that out of a total of 13 respondents (100%) who have poor tooth brushing habits, there are 7 respondents (53.8%) who have a small number of colonies and 6 respondents (46.2%) who have many colonies. Meanwhile, out of a total of 41 respondents (100%) who had the habit of brushing their teeth well, it was found that 41 respondents (100%) had a small number of colonies and none had many colonies. Based on the Chi-Square test, the results obtained were p = 0.000. Because p = 0.000 0.05, it can be interpreted that there is a relationship between brushing teeth and the number of candida fungal colonies in dental caries in children under 10 years of age. This can also be interpreted as meaning that the better the habit of brushing your teeth, the fewer the number of candida fungal colonies, and vice versa.

Correlation between Parents' Knowledge of Calcium Foods and Dental Caries Experience in Preschool Children

Problem statement: The prevalence of caries in Indonesia in children aged 3-4 years is 81.5% with a def-t score of 6.2 and the prevalence of caries in children aged 5 years is 90.2% with a def-t score of 8.1. Preschool children are prone to dental caries, one of the dental and oral health service efforts that can be done is in the form of preventing dental and oral diseases. It has been found that foods and drinks containing calcium can help prevent dental caries. Purpose: This study aims to determine whether there is a relationship between parents' knowledge of calcium-based foods and the dental caries experience of preschoolers at IT Al-Hikmah Kindergarten, Cirebon City. Method: This study used a cross-sectional design. The population in this study were all children and parents of TK Al-Hikmah Cirebon City with a total sample of 60 parents and 60 children. Analysis of the results of the study using the Spearman rank test. Results: The majority of parents' knowledge about calcium-based foods was good (55%) and the category of dental caries experience for preschoolers was very low (26.7%). Parents with good knowledge and their child's caries experience rate is very low (21.7%). The Spearman rank test results have a significance value of 0.00 and a correlation coefficient value of -0.580. Conclusion: there is a significant relationship with moderate strength and not in the same direction between parents' knowledge about calcium foods and preschool children's caries experience.