# Vitamin D and Vitamin D Receptor Polymorphisms Relationship to Risk Level of Dental Caries
## 3 Results  
### Vitamin D Receptor Gene Polymorphisms  
To discuss possible relations between VDPP and caries, we needed to report on the possible alleles of the polymorphisms of the VDR gene, presented in Table 1.  
Figure 1: Prisma flow chart of the present study. * Eligibility criteria were articles using DMFT diagnostic criteria with calibrated examiners, probability sampling, and sample sizes. ** We excluded studies conducted on institutionalized patients. From our findings we can support the fact that all relevant studies are differentiated in both methodology and sample size, thus revealing differences in the hypothesis that certain polymorphisms may play a specific role in caries risk assessment (Table 2). For example, [PERSON] et al. found a correlation between the _Bsml_ polymorphism containing the Bb genotype and increased risk of caries in deciduous teeth of Chinese children [18]. On the other hand, two studies in the Chinese population did not show a statistically significant difference between the caries-free and caries-active groups [19; 20]. In numerous studies, no statistically significant difference was found for a higher caries prevalence in the population with _Apal_ polymorphism [18; 19; 20; 21]. In the case of the _Taql_ polymorphism, one study suggested the allele 't' as a possible genetic factor for determining dental caries in Chinese individuals because the 't' allele was more frequent in the caries-active group [22]. Similar results were found by [PERSON] et al. [19] concerning the _Taql_ polymorphism, showing a statistically significant difference in _Taql_ genotypes between the case and control groups. On the other hand, many other case-control studies did not report significant differences in allele and genotype frequency of the _Taql_ polymorphism between individuals with and without caries [18; 19; 20; 23; 24]. Further, the _BgII_ polymorphism has been studied by two research groups in the Brazilian population. The authors concluded that the _BgII_ polymorphism was not associated with an increased risk of dental caries in the respective population [25; 26]. From all polymorphisms studied, the _Fokl_ polymorphism, distinguished in _rs10735810_ and _rs2228570_, is reported to play a significant role in the issue studied here. Although two studies supported that different alleles and genotypes of _rs10735810_ were not associated with tooth decay in Chinese and Turkish populations [18; 19], two other studies found a statistically significant difference when the _Fokl_ _rs10735810_ genotype was present in Chinese and Brazilian populations [20; 25]. In terms of the _rs2228570_ polymorphism, no correlation was found regarding a higher dental caries risk in the Brazilian population [25; 26]. A systematic review and meta-analysis compared the influence of the _Apal_, _Fokl_ _(rs10735810)_, _Taql_, _Bsml_, _Fokl_ _(rs2228570)_, and _BgII_ polymorphisms of the VDR gene on dental caries risk [15]. Based on nine studies, the meta-analysis reported an association between the _Fokl_ _(rs10735810)_ polymorphism and dental caries risk in children, with the f allele and the ff genotype reported as having a protective role. Additionally, authors found that there was no association between the _Apal_ _(rs7975232)_, _Taql_ _(rs731236)_, _Bsml_ _(rs1544410)_, _Fokl_ _(rs2228570)_, and _BgII_ _(rs739837)_ polymorphisms of the VDR gene and the prevalence of dental caries in children [15]. The authors claimed that the protective role of the f allele and ff genotype might be due to their interactions with co-transcription factors and location [15]. It is then concluded that there is a lack of consistency among the case-control studies reported here, their results related to the different VDR gene polymorphisms, and their influence on dental caries risk [27; 28; 29]. This fact is attributed to the statistical heterogeneity among studies, the small number of existing relative studies, and the small sample sizes.