Early childhood caries (ECC) is defined as the presence of one or more caries (non-cavitary or cavitary lesions), missing due to caries or filled tooth surfaces in any primary tooth in a child 71 months of age or less (Drury et al., 1999). The consequences of unmanaged ECC and premature tooth loss include pain and infections, speech disorders, and can lead to poor growth in weight and height (Ayhan et al., 1996 and Low et al. , 1999). Due to the increasing number of children with ECC (Tinanoff and Reisine, 2009), preventing the onset and progression of dental caries is important for the oral health and overall health of children. Say no to plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”?Get the original essay Many causal factors play a role in the development of tooth decay, including bacteria, diet, hygiene oral health, medical problems, and lack of important vitamins and minerals, such as vitamin D. Vitamin D is a steroid hormone essential for bone growth and remodeling, as well as tooth development, especially in the early stages of morphogenesis, differentiation and development of enamel and pulp (Glijer et al., 1985). . The main physiological function of vitamin D is to maintain serum calcium and phosphorus levels; without vitamin D, intestinal absorption of dietary calcium and phosphorus is significantly reduced (Holick, 2007). When serum calcium (Ca++) levels decrease, parathyroid hormone (PTH) levels increase, which increases tubular Ca++ resorption and enhances the action of osteoclasts to mobilize bone Ca stores. Additionally, PTH stimulates the kidneys to convert 25(OH)D into its active form of vitamin D, 1,25-dihydroxy vitamin D (Schroth et al., 2012 and Holick, 2006). At least 1 billion people worldwide have vitamin D intake. D deficiency or insufficient levels of vitamin D (Holick, 2007). Vitamin D deficiency is defined as a 25-hydroxyvitamin D (25(OH) D) level below 20 ng per milliliter (Hujoel, 2013). There are many causes of vitamin D deficiency, including hereditary disorders, acquired disorders, and reduced synthesis of vitamin D absorbed through the skin (Holick, 2007) (Schwalfenberg, 2011). Vitamin D deficiency can contribute to a number of conditions, including vitamin D-resistant rickets, osteoporosis, tooth enamel hypoplasia, and tooth decay. Breastfed children are at increased risk of vitamin D deficiency if they do not receive adequate sun exposure or vitamin D supplements. Additionally, children who receive insufficient vitamin D due to exposure to sun or diet may be at risk of ECC (Holick, 2007). Some experiments have shown that giving a mother vitamin D supplements while she is pregnant can reduce the rate of tooth enamel defects in their children. Defects in tooth enamel increase a child's risk of developing tooth decay (Cockburn et al., 1980). Much of the initial attention to the role of vitamin D in caries occurred in the 1920s and 1930s through the efforts of Mellanby and colleagues (Mellanby et al., 1924; Mellanby, 1928; Mellanby and Pattison 1928). Several historical reports document the beneficial effects of vitamin D supplementation in reducing dental caries in children (Mellanby et al., 1924; Mellanby and Pattison, 1926; McBeath, 1933; Anderson et al., 1934; Eliot et al.al., 1934; McBeath. and Zucker, 1938; McBeath and Verlin, 1942). Many studies have shown that geographic location and sun exposure are linked to dental caries. People living closer to the equator and more exposed to sunlight are less likely to develop dental caries (Grant, 2011). Studies that give people vitamin D supplements to prevent cavities have shown that vitamin D is effective in preventing the development of cavities (Hujoel, 2013). Schroth et al. (2012) conducted a pilot study in which 38 participants (19 controls and 19 patients with severe SCC) were assessed to determine their adequate levels of vitamin D and PTH. His study reported that children with severe CPE had lower vitamin D levels than caries-free controls. Hujoel (2013) hoped to further research the link between vitamin D and tooth decay. The results of this systematic review and meta-analysis reaffirm the importance of vitamin D for dental health: children deficient in vitamin D have delayed tooth eruption and are prone to dental caries. Schroth et al. (2013) conducted a research to study the association between serum 25(OH)D and S-ECC concentrations in preschool children. They found that children with S-ECC appeared to have relatively poor nutritional health compared to caries-free controls and were significantly more likely to have low concentrations of vitamin D, calcium and albumin and high PTH levels. Maguire et al. (2013) conducted a study to examine the association between cow's milk consumption and vitamin D and iron stores in healthy urban preschool children. They found that two cups (500 ml) of cow's milk per day maintained 25-hydroxyvitamin D levels >75 nmol/L with minimal negative effect on serum ferritin for most children. Children with darker skin who do not receive vitamin D supplementation during the winter need 3 to 4 cups of cow's milk per day to maintain a 25-hydroxyvitamin D level > 75 nmol/L. Consumption of cow's milk in bottle-feeding children did not increase 25-hydroxyvitamin D and resulted in a more dramatic decrease in serum ferritin (Maguire et al., 2013). Another study by Lee et al. (2014) investigated the association between total daily consumption of serum levels of non-cow's milk and 25-hydroxyvitamin D in a population of healthy urban preschool children and analyzed the association between daily consumption of non-cow's milk and consumption of cow's milk They found that consumption of non-cow's milk drinks was associated with a 4.2-25 nmol/L decrease. -hydroxyvitamin D per 250 ml cup consumed in children who also drank cow's milk Children who drank only non-cow's milk had a higher risk of having a 25-hydroxyvitamin D level below 50 nmol. /L. than children who drank only cow's milk (Lee et al., 2014). Mothers of children with CPE have lower vitamin D levels during pregnancy than mothers whose children do not have caries (Schroth et al., 2014). reported that pregnant women with higher prenatal vitamin D intakes were more likely to report that their child was caries-free than women with lower vitamin D intakes (Tanaka et al., 2015). Data from a cross-sectional study suggest that there is an association between caries and reduced serum vitamin D levels. Improving the vitamin D status of children may be a = 0.05.