As a populous province, Shandong province has a population of nearly 100 million people. The current study collected eligible samples to represent the oral health status of this province and cover areas with different dietary habits. Finally, out of a total of 1330 children aged 3-5-year-old, 1301 families provide complete and reliable data information, the response rate is as high as 97.8%, this is very satisfying.
The caries prevalence for 3-5-year-old children in Shandong province are 51.1%, 67.8–73.9% respectively, which all higher than the national level (50.8%, 63.6%, 71.9%), while the dmft mean and the untreated rate of dental caries are lower than the national data (3.15 vs 3.35; 96.4% vs 96.9%)[17]. Compared to some other developing countries in Asia, Thailand (age 5: 78.5%)[18], Indonesia (age 0–5: 70.0%)[19], Myanmar (age 5–6: 81.3%) and Cambodia (age 3: 84.9%) [20], all have higher rates of ECC. While in developed countries like Japan and Singapore, the ECC rates are down to 44.4% and 49% respectively[21, 22], which is significantly lower than the results of 63% obtained by statistics worldwide[23] and has already achieved the goal of less than 50% prevalence of ECC for the year of 2020 raised by WHO [24]. These data alert us there is still a long and tough way to go to reduce the prevalence of ECC in Shandong, China.
Age has been evidenced to be an independent risk factor of ECC by many studies [13, 20, 25], and this finding was corroborated in current study. Most researches, however, evaluate 3-5-year-old children as whole with few studies access the risk factors for each age. Therefore, we speculated that although the age span is small, different ages may have different risk factors. Exactly, both the Chi-square test and the logistic regression model in present study confirm this speculation (Table 2–4). Despite different age groups share a caries-related risk factors—the experience of toothache over the past year, the increased risk for ECC in children aged 3 is independently associated with the feeding method within 6 months after the birth, while the 5-year-old children are primarily associated with the frequency of bedtime sweets. This heterogeneity indicates that we should have different priorities when it comes to OHE for preschool children of different ages.
The association between feeding method and ECC is pretty intricated and involves in a variety of factors including the frequency, duration, numbers, time and formula of the feeding. Previous studies ever reported that the breastfeeding and its duration is not associated with the ascended risk of ECC [13], yet studies also found that both prolonged breastfeeding and high-frequency feeding in late infancy augments the risk of having dental caries[26, 27]. Van Palenstein et al[28], interestingly, reported that breastfeeding during the daylight beyond the age of 12-month was not associated with ECC for 25- to 30-month old infants, the relevant factor is breastfeeding at night > 2 times, and exposing > 15 minutes per nocturnal feeding. Although the current study also provides evidence that breastfeeding has a greater adverse impact on ECC than artificial feeding, similar to the results of national studies 10 years ago[29], no more details information about the duration, frequency, time, formula were collected, so it’s hard to analyze and attain those specific factors that have caused such outcomes. After all, the high cariogenic of bottle feeding has also been confirmed by many studies[30]. One latest research contributes evidence for the nonlinear association between breastfeeding duration and ECC and the auxiliary role of fluoridated water in reducing the negative effects of feeding on ECC[31]. That reminds us more relevant variables need to be considered in future studies to elucidate the correlation between feeding methods and ECC.
Frequent exposure to dietary sugar and refined carbohydrates is well recognized to be associated with ECC[32–35], bedtime sweet is particularly serious[33, 36]. Excessive sugar consumption provides abundant nutrients for the supragingival microorganisms and induces acid production, enamel-dentine demineralization, and then caries formation[11, 37]. The limitation of sugar consumption has therefore been listed in the Declaration that gained worldwide support[38]. Interestingly, the data from this present study found that the increase in the frequency of bedtime sweets did not become an independent risk factor for ECC in children aged 3 and 4, but only work for children aged 5 years. It is not possible from these data to conclude that there is no need to pay attention to sugar consumption habits under 4 years old, because sweet preference has also been evidenced to be a high risk factors of ECC for children under 23 months in Japan[36]. Scholar Leroy et al. [39]and Schluter et al.[40] also respectively confirmed that bedtime sweet is significantly associated with ECC for children aged 3 and 4. Accordingly, it is possible that the outcomes of previous undesirable sugar consumption habits exactly show up at 5 years old and become an independent risk factor for the current study sample. This is in full compliance with the action of time factors in the pathogenesis of dental caries[11]. Therefore, even though the sugar habits in this study were only risk factors for the 5-year-old group, knowledge transmission and behavioral intervention definite should be carried out early in life.
Previous studies ever found that infrequent dental visits were correlated with an augmented risk for untreated caries[41, 42]. Some studies, however, reported a positive association between the number of dental visits and ECC prevalence[13, 43]. This finding is consistent with the results of the current study. Unfortunately, this result goes against the goal of oral prevention. The design of the dental visit is expected to play a positive and energetic role in caries prevention[44], while 51.8% of families in present study sought help from a dentist for treatment compared to only 7.8% came for prevention. An Australian study reported that dental visit actually contributes 30.3% in explaining inequalities in ECC[15]. This indicates that our awareness of prevention is still insubstantial, the purpose of dental visit is incorrectly implemented as more for treatment, and rarely for prevention. This definite is one of the priorities we need to improve.
Tooth brushing has always been considered as the primary and most effective way to clean plaque microbes and prevent dental caries. Many studies have confirmed the association between tooth-brushing and ECC[45, 46]. While plenty of studies have also verified that there is no correlation between these two variables[47, 48], which is consistent with the results of the present study. Abdelaziz et al.[49] ever reported that brushing was not an independent risk factor of ECC and S-ECC for preschool children. Edward Lo even found that supplemental training in parental toothbrushing would not be benefit to the reduction of ECC for those children under 3 years of age who lived in a water fluoridated area and had been provided the OHE sufficiently[50]. To be sure, however, the earlier of oral preventive intervention, the lower risk of ECC[14, 29], the present study also confirms this trend in bivariate analyses, but not to be an independent risk factor. Honestly, interpretation of the results relevant to such issues is further limited in the deficiency of information about brushing details. For example, brushing duration, brushing compliance, floss assistance, and especially brushing efficiency assessment are not available in our data, it is therefore difficult to objectively assess the association between tooth-brushing and ECC in the scenario of many factors being masked or even neglected. Further studies should include these variables so we can attain a clearer picture for the role of toothbrushing on ECC prevention.
It must also be said that the current status and issues of oral health education are well demonstrated in present study. First of all, a sharp contrast between the high awareness of oral health routine knowledge (66%-98.8%) and the low access to oral prevention knowledge (16%-35.8%), the negative association between correct cognition and ECC risk (Appendix table S1, Table 2–4), and the positive correlation between frequency of toothache and dental visit and ECC all reflect that human information behavior[51] seems to be underperforming in impelling people’s practice for ECC prevention, and oral health promotion, related policies, and even the dentist itself also seems to be underperforming. However, many studies have confirmed that when a more systematic, proactive oral health intervention involving brushing training, referral and dental care is implemented for a family with children, even if implemented by non-dental professionals[52], it generally has a greater preventive effect against ECC[44, 53–56]. Therefore, a systematic and sound oral health care program is imperative[57], which involves in clinical care, brushing training, referral and so on, rather than just oral health education, only this way can make sure the consistency between theoretical knowledge and actual action as much as possible, thus reducing the incidence of ECC. In addition, the risk factors for ECC at different ages (3-5-year-old) are not completely consistent. In current study, the early stage of deciduous dentition(3 years old) is mainly related to feeding methods, the late stage of deciduous dentition(5 years old) is mainly associated with sugar-eating habits, which indicate that a more strategic and more targeted OHE method and content are supposed to be designed for children of different ages, this would be more cost-effective. Finally, although the positive association between the tooth-brushing, using of fluoride and the low risk of dental decay was not obtained in this study, its role in caries prevention is indeed indelible[14, 58, 59]. Therefore, assisting children to master these knowledge and skills early in life is the responsibility of dentist and parents.
The main advantage of this study is its large representative sample of children and its high response rate. Limitations include the issues in the OHC knowledge and attitude designed for the questionnaire are relatively basic and traditional. Several major risk factors are incorporated in current study, but unlike those monographic researches which excavated and explored sufficient detailed information about one certain targeting factor associated with ECC[27, 31, 50]. We have to say that some data on detailed information is limited, such as frequency of bedtime feeding, brushing efficiency, floss assist status, cariogenic microbial flora, each of which is reported to be associated with ECC. Therefore, more information is waiting to be collected to further analyze the risk factors associated with ECC for each age group.