Early childhood caries (ECC) is defined as the presence of 1 or more decayed lesions (noncavitated or cavitated), missing due to caries, or filled tooth surfaces in any primary tooth in a child 71 months of age or older young (Drury et al. al., 1999). The consequences of unmanaged ECC and premature tooth loss include pain and infection, speech disorders and may result in poor weight and height growth (Ayhan et al., 1996 and Low et al., 1999). Due to the increasing number of children presenting with ECC (Tinanoff and Reisine, 2009), preventing the onset and progression of dental caries is important for children's oral health and overall health. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay There are many causal factors that play a role in the development of dental caries, including bacteria, diet, oral hygiene, medical conditions, and lack of important vitamins and minerals, such as vitamin D. Vitamin D is an essential steroid hormone for bone growth and remodeling, as well as for tooth development, particularly 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 levels of calcium and phosphorus; without vitamin D, intestinal absorption of dietary calcium and phosphorus is significantly reduced (Holick, 2007). As serum calcium (Ca++) levels decrease, parathyroid hormone (PTH) levels increase, in turn, increasing tubular reabsorption of Ca++ and enhancing the action of osteoclasts to mobilize Ca stores from bone. Furthermore, PTH stimulates the kidneys to convert 25(OH) D to its active form of vitamin D, 1,25-dihydroxy vitamin D (Schroth et al., 2012 and Holick, 2006). At least 1 billion people worldwide take vitamin D deficiency or insufficient levels of vitamin D (Holick, 2007). Vitamin D deficiency is defined as a 25-hydroxyvitamin D (25(OH) D) level less than 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, hypoplastic tooth enamel, and dental caries. Breastfed infants are at increased risk of vitamin D deficiency if they do not receive adequate exposure to sunlight or vitamin D supplements. Additionally, infants who receive inadequate vitamin D through sun exposure or diet may be at risk for ECC (Holick, 2007). Some experiments have found 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 dental caries (Cockburn et al., 1980). Much of the initial attention to the role of vitamin D in tooth decay occurred during the 1920s and 1930s through the efforts of Mellanby and colleagues (Mellanby et al., 1924; Mellanby, 1928; Mellanby and Pattison 1928). Numerous 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., 1934; McBeath and Zucker, 1938; McBeath and Verlin, 1942). Many studies have found that geographic location and sun exposure are related to dental caries. People who live closer to the equator with greater sun exposure are less likely to developdental caries (Grant, 2011). Studies that have administered vitamin D supplements to prevent tooth decay have found that vitamin D is effective in preventing the development of tooth decay (Hujoel, 2013). Schroth et al., (2012) conducted a pilot study in which 38 participants (19 controls and 19 patients with severe ECC) were assessed for adequate levels of vitamin D and PTH. His study reported that children with severe ECC have lower vitamin D levels than caries-free controls. Hujoel, (2013) hoped to further investigate 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) initiated research to investigate the association between serum 25(OH)D concentrations and S-ECC 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 vitamin D, calcium, and albumin concentrations and elevated PTH levels. Maguire et al. (2013) conducted a study to examine the association of cow's milk intake on both 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 >75 nmol/L with minimal adverse effect on serum ferritin for most children. Children with darker skin pigmentation who did not receive vitamin D supplementation during the winter required 3 to 4 cups of cow's milk per day to maintain 25-hydroxyvitamin D >75 nmol/L. Cow's milk intake among bottle-feeding infants did not increase 25-hydroxyvitamin D and resulted in more dramatic decreases in serum ferritin (Maguire et al., 2013(. Another study by Lee et al. (2014) studied 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 -nmol/L decrease in 25-hydroxyvitamin level. D per 250 ml cup consumed among children who also drank cow's milk. Children who drank only non-cow's milk were at increased risk of having a 25-hydroxyvitamin D level below 50. nmol/L compared to children who drank only cow's milk (Lee et al., 2014) Mothers of children with ECC have lower vitamin D levels during pregnancy than mothers whose children do not have tooth decay (Schroth et al ., 2014). stated that pregnant women with a higher prenatal vitamin D intake were more likely to report that their baby was free of tooth decay compared to women who had a lower vitamin D intake (Tanaka et al., 2015). Data from a cross-sectional study suggested that there is an association between tooth decay and lower serum vitamin D levels. Improving children's vitamin D status may be an additional preventative consideration to reduce tooth decay risk (Schroth et al., 2016). The purpose of the study: to determine whether there is a relationship between vitamin D deficiency and the development of early childhood caries (ECC). Methodology: This is a pilot case-control study to determine the relationship between vitamin D deficiency and the prevalence and severity of ECC. Patient selection and examination according to inclusion and exclusion criteria, an informed consent form = 0.05.