Iron Deficiency and Early Childhood Caries: A Systematic Review and Meta-Analysis
Early childhood caries (ECC) is one of the most prevalent chronic diseases affecting preschool children, primarily impacting their primary teeth. Recent clinical and epidemiological studies have highlighted a potential association between iron deficiency (ID) or iron deficiency anemia (IDA) and the occurrence of dental caries in children. This systematic review and meta-analysis aim to comprehensively evaluate the scientific evidence regarding the intrinsic relationship between ID and ECC, incorporating data from multiple studies to provide a robust conclusion.
The study was conducted by searching various electronic databases, including PubMed, Web of Science, Cochrane, China National Knowledge Infrastructure (CNKI), Wanfang, and the Database for Chinese Technical Periodicals, from March 2020 to September 2020. The search utilized Medical Subject Headings (MeSH) terms and free words related to dental caries, preschool children, infants, and iron deficiency. The inclusion criteria focused on observational studies that investigated the relationship between ECC and ID or IDA in children under six years old. Studies were required to define ID or provide serum ferritin levels below 30 mg/L without inflammation, and IDA was defined based on abnormal blood tests for serum ferritin, hemoglobin (HGB), and mean corpuscular volume (MCV). Excluded studies were those without direct comparisons between ECC and ECC-free groups, incomplete data, or non-primary research articles.
A total of 12 case-control studies published between 2002 and 2019 were included in the meta-analysis, encompassing data from 9981 children. These studies originated from various countries, including India, China, the United States, Canada, Iran, and Egypt. The meta-analysis was performed using the Cochrane Collaboration’s Review Manager 5.3 software, employing random-effects models to account for heterogeneity when necessary.
The findings revealed a significant association between ID and ECC. Children with ECC were more likely to have ID, with an odds ratio (OR) of 2.63 and a 95% confidence interval (CI) of [1.85, 3.73], indicating a strong statistical significance (P < 0.001). However, no statistically significant association was found between serum ferritin levels and ECC, with a weighted mean difference (WMD) of -5.80 and a 95% CI of [-11.97, 0.37] (P = 0.07). The analysis also showed that children with ECC were more likely to have IDA, with an OR of 2.74 and a 95% CI of [2.41, 3.11] (P < 0.001). Additionally, HGB levels in the ECC group were significantly lower compared to the ECC-free group, with a WMD of -9.96 and a 95% CI of [-15.45, -4.46] (P = 0.0004). Similarly, MCV levels in the ECC group were significantly lower than those in the ECC-free group, with a WMD of -3.72 and a 95% CI of [-6.65, -0.79] (P = 0.01).
The study also explored potential mechanisms underlying the association between ID and ECC. One hypothesis suggests that salivary gland function is impaired in ID, affecting salivary secretion and buffering capacity, which are crucial in preventing dental caries. Another theory posits that ferric ions in the blood decrease during ID, and iron has anti-caries properties. Iron ions can inhibit the activity of Streptococcus mutans, a primary cariogenic bacterium, and can also supplement minerals dissolved in the acidic oral environment by combining with calcium and phosphate ions.
Furthermore, the study highlighted common risk factors for both ECC and ID, such as socio-economic status and malnutrition. IDA is prevalent in children under five years old, primarily due to nutritional deficiencies. Economic limitations can lead to malnutrition, which may delay the eruption and replacement of primary teeth, increasing the risk of ECC. The study also noted that children with ECC often experience inflammation and necrosis in the pulp of their primary teeth, leading to changes in chewing habits and reduced intake of iron-rich foods, exacerbating IDA.
The meta-analysis also addressed the limitations of the included studies. The criteria for diagnosing ID and IDA varied across studies, and the sample sizes ranged widely, potentially affecting the generalizability of the findings. Additionally, most of the included studies focused on populations of yellow race, limiting the applicability of the results to other ethnic groups. The study emphasized the need for further research to explore the caries experience between ID and ID-free groups to establish a more definitive causal relationship.
In conclusion, this systematic review and meta-analysis provide substantial evidence that ID is more prevalent in children with ECC, and markers of iron status, such as serum ferritin, HGB, and MCV, are relatively lower in the ECC group compared to the ECC-free group. The findings underscore the importance of addressing nutritional deficiencies, particularly iron deficiency, in preventing and managing early childhood caries. Future studies should aim to standardize diagnostic criteria and include diverse populations to enhance the robustness and applicability of the findings.
doi.org/10.1097/CM9.0000000000001729
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