# Vitamin D and Vitamin D Receptor Polymorphisms Relationship to Risk Level of Dental Caries
## 3 Results
### Vitamin D Receptor Gene Polymorphisms
Furthermore, nine studies have investigated the relationship between VD deficiency and ECC or S-ECC. More specifically, there was a negative correlation between VDD and increased risk of ECC [36; 37; 38; 39; 40; 41; 42; 43; 44; 45]; for example, [PERSON] et al. [41] stated that deficient cord blood 25(OH)D levels (\(<\)30 nmol/L) had a significant impact on the dmft in the follow-up period between 12 and 35 months of infants' age, with dmft scores that were double in relation to nondeficient concentrations. In the same study, no significant association between insufficient levels of 25(OH)D (\(<\)50 nmol/L) and ECC was reported. In another study, with a significant sample size of 1510 Chinese children, VD deficiency and insufficiency led to an increased risk of ECC [38]. [PERSON] et al. suggested supplementation of VD to prevent dental caries because VDD is a significant risk factor for dental caries in children [39]. In addition to VDD, children with S-ECC showed significantly lower levels of Ca and serum albumin and higher levels of PTH [40]. Deficient and insufficient levels of VD led to a higher odds ratio for S-ECC in children compared to optimal VD levels, according to two studies that have been conducted in Canada and North America [43; 44]. Only one case-control study reported levels of VD in children without caries comparatively higher than in children with severe caries at a mean age of 40.82 months, even if the mean levels of VD were close to optimal [42]. A cross-sectional study with a sample of 1638 children from Poland concluded that the prevalence of ECC and S-ECC was significantly lower in children receiving VD supplementation. The authors also reported that children and mothers of higher education received VD supplementation and had fewer caries, highlighting the socioeconomic background of ECC [45]. In six out of nine studies addressing the issue, it is reported that socioeconomic factors, and especially the mothers' educational background, have a negative impact on caries risk and a positive effect on levels of VD. Furthermore, many studies have investigated the relation between 25(OH)D levels and dental caries risk in mixed dentition, of which eight are included in this study. In all studies included here, there seems to be a weak indication that improving children's VD status might be an additional preventive measure against caries during the period of mixed dentition. In more detail, a cross-sectional study with a sample of 1017 Canadian children from 6 to 11 years of age stated that optimal levels of 25(OH)D (>75 nmol/L) had a significantly lower odds ratio for caries [46]. Further, [PERSON] et al. reported a weak association between the risk of dental caries and 25(OH)D serum, and the authors did not recommend supplementation of VD as a preventive measure for managing dental caries [47]. A weak inverse correlation between VD and dental caries risk in mixed dentition was found also in another study with a sample of 206 Swedish children [48]. Supplementation of VD and fluoride during the entire first year of a child's life led to a lower probability of caries-related restorations at the age of 10 in primary teeth in relation to children who received the same supplementation for less than 6 months [49]. A cohort study with a sample of 335 Portuguese children and a mean age of 7 years reported that 25(OH)D levels less than 30 ng/mL were associated with advanced dental caries in permanent teeth, while no statistically significant difference was found in terms of 25(OH)D levels and dental caries risk in mixed dentition [50]. The same results, regarding mixed dentition, were reported in a study with a sample of 121 Polish children with growth hormone deficiency. There was no statistically significant impact of VD on the mean DMFT index, but the authors recommended VD as a potentially effective agent in reducing dental caries, especially for growth hormone deficiency patients [51].