Lack of Association between BMP2/DLX3 Gene Polymorphisms and Dental Caries in Primary and Permanent Dentitions
CARIES RESEARCH
Authors: Kastovsky, Jakub; Linhartova, Petra Borilova; Musilova, Kristina; Zackova, Lenka; Kukletova, Martina; Kukla, Lubomir; Holla, Lydie Izakovicova
Abstract
The aim of this study was to analyze the association between BMP2 (rs1884302) and DLX3 (rs2278163) gene polymorphisms and dental caries in primary and permanent dentitions. A total of 914 subjects were genotyped by the TaqMan methods: 176 caries-free children (with Decayed/Missing/Filled Teeth, DMFT = 0), 542 patients with dental caries in permanent dentition (DMFT >= 1), 83 caries-free children with primary teeth (with decayed/missing/filled teeth, dmft = 0), and 113 children with early childhood caries (ECC, dmft >= 1). There were no significant differences in allele/genotype frequencies between patients with caries in permanent dentition/ECC and caries-free children or between patients with very low (DMFT = 0-2), low (DMFT = 3-5), moderate (DMFT = 6-8), or high (DMFT >= 9) caries experience. Variability in BMP2 and DLX3 was not associated with caries in the Czech population. (c) 2017 S. Karger AG, Basel
Ameloblast Modulation and Transport of Cl-, Na+, and K+ during Amelogenesis
JOURNAL OF DENTAL RESEARCH
Authors: Bronckers, A. L. J. J.; Lyaruu, D.; Jalali, R.; Medina, J. F.; Zandieh-Doulabi, B.; DenBesten, P. K.
Abstract
Ameloblasts express transmembrane proteins for transport of mineral ions and regulation of pH in the enamel space. Two major transporters recently identified in ameloblasts are the Na+K+-dependent calcium transporter NCKX4 and the Na+-dependent HPO42- (Pi) cotransporter NaPi-2b. To regulate pH, ameloblasts express anion exchanger 2 (Ae2a,b), chloride channel Cftr, and amelogenins that can bind protons. Exposure to fluoride or null mutation of Cftr, Ae2a,b, or Amelx each results in formation of hypomineralized enamel. We hypothesized that enamel hypomineralization associated with disturbed pH regulation results from reduced ion transport by NCKX4 and NaPi-2b. This was tested by correlation analyses among the levels of Ca, Pi, Cl, Na, and K in forming enamel of mice with null mutation of Cftr,Ae2a,b, and Ame/x, according to quantitative x-ray electron probe microanalysis. lmmunohistochemistry, polymerase chain reaction analysis, and Western blotting confirmed the presence of apical NaPi-26 and Nckx4 in maturation-stage ameloblasts. In wild-type mice, K levels in enamel were negatively correlated with Ca and Cl but less negatively or even positively in fluorotic enamel. Na did not correlate with P or Ca in enamel of wild-type mice but showed strong positive correlation in fluorotic and nonfluorotic Ae2a,b- and Cftr-null enamel. In hypomineralizing enamel of all models tested, 1) Cl- was strongly reduced; 2) K+ and Na+ accumulated (Na+ not in Ame/x-null enamel); and 3) modulation was delayed or blocked. These results suggest that a Na+K+-dependent calcium transporter (likely NCKX4) and a Na+-dependent Pi transporter (potentially NaPi-2b) located in ruffle-ended ameloblasts operate in a coordinated way with the pH-regulating machinery to transport Ca2+, Pi, and bicarbonate into maturation-stage enamel. Acidification and/or associated physicochemical/electrochemical changes in ion levels in enamel fluid near the apical ameloblast membrane may reduce the transport activity of mineral transporters, which results in hypomineralization.