Systematic Review Examines the Association of Vitamin D and Dental Caries in Children

Nutrition plays a critical role in oral and systemic health. While dental caries is a multifactorial disease, it is primarily driven by the disruption of the oral microbiome, or dysbiosis, which is often initiated by dietary choices. Vitamin D is crucial for proper tooth, oral, and craniofacial development. A deficiency during odontogenesis can lead to enamel hypoplasia, a confirmed risk factor for dental caries. This is because enamel hypoplasia can promote attachment and colonization of pathogenic biofilm on the tooth surface.¹

The most accurate measure of vitamin D levels is the serum 25-hydroxyvitamin D [25-(OH) D]. This compound is produced in the liver and then metabolized in the kidneys to 1,25-dihydroxyvitamin D [1,25-(OH) 2D].¹ While vitamin D is obtained from two sources – endogenous vitamin D3 (produced in the skin via UVB radiation), and exogenous vitamin D3 (from dietary supplements and food) – studies show up to 90% of the body’s vitamin D is generated endogenously.^1,2 As a key player in calcium absorption, 1,25-(OH) 2D is essential for the formation and development of bones and teeth.¹

A growing body of research has associated vitamin D deficiency with various oral health issues. Studies indicate that a lack of vitamin D during deciduous and permanent tooth formation can increase the risk of fractures and dental caries in under-mineralized teeth, as well as contribute to poor periodontal health. Furthermore, vitamin D deficiency in pregnant individuals can affect fetal ameloblasts, which can lead to enamel hypoplasia and an increased risk of dental caries in children.¹

Multiple hypotheses have been proposed to explain the impact of vitamin D on oral health. These include improved tooth development, better dentin mineralization, topical fluoride impact, changes in saliva, and alterations in biochemical composition.¹

Beyond its role in mineralization, vitamin D may also influence oral health through other biological mechanisms. For instance, some research suggests that specific genetic polymorphisms could affect vitamin D uptake and contribute to caries development. Other studies suggest that vitamin D’s role in regulating the immune response may be a key factor, as it activates the production of antimicrobial proteins that inhibit both gram-negative and gram-positive bacteria, thus helping to reduce caries risk.¹

Despite numerous published studies on the relationship between vitamin D and dental caries, the exact nature of this association remains ambiguous. To address this knowledge gap, a systematic review and meta-analysis was conducted. The objective was to evaluate “the association between a higher experience of dental caries and lower serum vitamin D levels in children.”¹

The Study

A search was conducted across four electronic databases: PubMed, Embase, Web of Science, and Cochrane Library. The search was specific to studies investigating the epidemiological association between vitamin D levels and dental caries in children. The inclusion criteria were:¹

1. 1. Cohort, case-control, and cross-sectional studies
   2. Subjects were children under 19 years old
   3. The study’s exposure factors were vitamin D deficiency (serum 25-(OH) D < 50 nmol/L as deficiency, and ≥ 50 nmol/L as normal)
   4. Outcome indicators included caries, missing teeth, the number of filled teeth, and dental caries experience
   5. Relative risk (RR) and its corresponding 95% confidence interval (95%CI) were provided or could be calculated
   6. For studies involving the same population, the study with the largest sample size or the most recent publication was selected

Exclusion criteria included repetitive literature, incomplete or unclear data, inconsistent outcome indicators, poor quality studies, case reports, commentaries, expert opinions, and narrative reviews.¹

The initial search yielded a total of 2,731 publications. After removing duplicates and irrelevant articles, 56 related studies were obtained. A final review using the inclusion and exclusion criteria resulted in 13 articles that were included in the systematic review and meta-analysis. The 13 included studies were observational and consisted of 3 case-control studies, 5 cohort studies, and 5 cross-sectional studies, which totaled 19,205 patients aged 1 to 19.¹

These included studies were assessed for quality, and most were found to have a low risk of bias. There was no evidence of funding bias, baseline imbalances, early stopping bias, or inadequate outcome data, which strengthens the reliability of the findings.¹

The Results

The systematic review and meta-analysis found that patients with vitamin D deficiency had a 22% higher risk of dental caries when compared to patients with normal vitamin D levels. Since dental caries are multifactorial, the authors adjusted for confounders like tooth brushing and socioeconomic status, which showed a slightly lower, but still significant, 16% higher risk.¹

Subgroup analyses were conducted on age and dentition status. In the permanent dentition group (2 studies), the risk of dental caries was 28% higher in patients with vitamin D deficiency. This risk was even more pronounced in the deciduous teeth subgroup (6 studies), where it was 68% higher. Conversely, the mixed dentition subgroup (4 studies) showed an 8% increase in caries risk.¹

Limitations

This study acknowledged several limitations. A number of the included studies were cross-sectional, which only suggests correlation rather than establishing a direct cause-and-effect relationship. Additionally, there were inconsistencies in how dental caries were measured across the studies, including the use of different indices (DMST/DMFS), a lack of specific cut-off points, and variation in whether cavitated and non-cavitated lesions were included. Finally, the authors noted the small sample size and suggested that larger cohort studies are needed to provide more reliable and accurate data.¹

Conclusion

Teeth, like bone, are mineralized organs, and disruption in this mineralization process can lead to improper tooth development. Vitamin D plays a crucial role in this process by facilitating calcium and phosphorus absorption, making a deficiency a potential factor in tooth decalcification. Furthermore, vitamin D deficiency is associated with various chronic systemic conditions like cardiovascular disease, metabolic syndrome, malignant tumors, autoimmune disorders, infections, kidney disease, and bone disorders.¹

Ultimately, this study’s findings provide new clarity on the topic by demonstrating a clear association between vitamin D deficiency and an increased incidence of dental caries in children. The results show that low 25-(OH) D levels are negatively associated with dental caries in children under 19, and these children have between a 16% to 22% higher risk of developing dental caries. The authors conclude that healthcare professionals should be mindful that prenatal nutrition and childhood dietary choices – specifically sufficient vitamin D intake – can potentially affect dental caries rates in children.¹

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References

1. Li, Z., Wei, X., Shao, Z., et al. Correlation between Vitamin D Levels in Serum and the Risk of Dental Caries in Children: A Systematic Review and Meta-Analysis. BMC Oral Health. 2023; 23(1): 768. https://pmc.ncbi.nlm.nih.gov/articles/PMC10585927/
2. Food Sources of Vitamin D. (n.d.). Dietary Guidelines for Americans. https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-sources-vitamin-d