FGF10 and FGF13 genetic variation and tooth-size discrepancies

Impact of FokI (rs2228570) and BglI (rs739837) polymorphisms in VDR gene on permanent tooth eruption: A cross-sectional study

Introduction

Genetic polymorphisms who disturb the mineral homeostasis during tooth development and eruption are candidate to clarify the molecular mechanisms involved in changes in the tooth eruption chronology. In this study, we evaluate whether the FokI (rs2228570) and BglI (rs739837) polymorphisms in the Vitamin D receptor (VDR) gene are associated with changes in the chronology of eruption of permanent teeth.

Material & method

This cross-sectional study randomly included 353 biologically unrelated children, both sexes, without systemic impairment or syndromes and history of trauma during the primary dentition. One operator perform the oral clinical examination. The tooth was considered erupted if there was a visible minimum of any tooth surface emerging from the mucosa. Genomic DNA was extracted from buccal epithelial cells from saliva samples. Genotyping was performed by Real-Time Polymerase Chain Reactions using TaqMan® technology. The average of the total number of erupted permanent teeth between the genotypes was compared by the Mann-Whitney test and multivariate Generalized Linear Models (GLM) (α = 5 %). β values with Confidence Interval (CI) 95 % were calculated.

Results

The heterozygous adenine-guanine genotype of the FokI significantly decreases the number of erupted permanent teeth (β = -1.15; CI 95 % = -2.22 to -0.07; p = 0.036). In the stratified analysis for maxillary and mandibular teeth, this genotype was associated with a decrease in the number of erupted maxillary permanent teeth (β = -0.65; CI 95 % = -1.22 to -0.09; p = 0.023). BglI was not associated with permanent teeth eruption.

Conclusion

The FokI, but not BglI, in the VDR may delay the eruption of permanent teeth.

Craniofacial anomalies in a murine model of heterozygous fibroblast growth factor 10 gene mutation

OBJECTIVE

Dysregulation of Fibroblast Growth Factor 10 (FGF10), a member of the family of Fibroblast Growth Factor (FGF) proteins, has been implicated in craniofacial and dental anomalies, including craniosynostosis, cleft palate, and Lacrimo-Auriculo-Dento-Digital Syndrome. The aim of this murine study was to assess the craniofacial and dental phenotypes associated with a heterozygous FGF10 gene (FGF10+/- ) mutation at skeletal maturity.

METHODS

Skulls of 40 skeletally mature mice, comprising two genotypes (heterozygous FGF10+/- mutation, n = 22; wildtype, n = 18) and two sexes (male, n = 23; female, n = 17), were subjected to micro-computed tomography. Landmark-based linear dimensions were measured for the cranial vault, maxilla, mandible, and first molar teeth. Multivariate analysis of variance was performed to assess whether there were significant differences in the craniofacial and dental structures between genotypes and sexes.

RESULTS

The craniomaxillary skeleton and the first molar teeth were smaller in the FGF10+/- mice (P < .05), but the mandible was unaffected. Sex did not have a significant effect on these structures (P > .05). Cranial sutural defects were noted in 5/22 (22.7%) mutant versus 2/18 (11.1%) wildtype mice, and cleft palate in only one (4.5%) mutant mouse. None of the mice displayed craniosynostosis, expansive bony lesions, bifid condyles, or impacted teeth.

CONCLUSION

The FGF10+/- mutation was associated with craniomaxillary skeletal hypoplasia that probably arose from deficient (delayed) intramembranous ossification of the sutured bones. Overall, the skeletal and dental data suggest that the FGF10 gene plays an important role in the aetiology of craniofacial dysmorphology and malocclusion.

Single nucleotide polymorphisms in odontogenesis-related genes associated with tooth-size discrepancy

Introduction: The present study aimed to determine the association between single nucleotide polymorphisms (SNPs) in RUNX2, SMAD6, BMP2, and BMP4 genes in relation to tooth-size discrepancy (TSD).

Methods: A cross-sectional study of patients undergoing orthodontic treatment measured the mesiodistal width of permanent teeth from pretreatment dental casts. Sixty-two patients were included in the study and TSD was assessed according to the Bolton analysis. The patients were allocated into a control group (without a TSD), an anterior excess group and an overall excess group. Genomic DNA was extracted from saliva samples, and SNPs previously associated with tooth size were evaluated using a real-time polymerase chain reaction (PCR) system. The Fisher exact test was performed to compare genotype and allele frequencies at an α = 0.05. An Odds Ratio (OR) and 95% Confidence Interval (95% CI) were calculated.

Results: The rs59983488 SNP in the RUNX2 gene was significantly related to the presence of anterior mandibular tooth-size excess in allele (T allele: p<0.001; OR = 11.74; 95% CI =2.61–55.80), and genotype models (GT genotype: p = 0.002; OR = 12.69; 95% CI = 2.47–64.83). The rs3934908 SNP in the SMAD6 gene was significantly associated with the presence of an overall maxillary tooth-size excess in allele (T allele: p < 0.001) and genotype models (TT genotype: p = 0.010).

Conclusion: The present results suggest that SNPs in RUNX2 (rs59983488) and SMAD6 (rs3934908) genes may be associated with the presence of tooth-size excess.

Influence of genotype and perioral musculature on maxillary and mandibular development

OBJECTIVES

To determine whether there is an association between skeletal jaw position and perioral musculature, and if genotypes can predict skeletal growth.

MATERIALS AND METHODS

A prospective study on 42 patients over 1 year was performed. The study included 22 females and 20 males with and average age of 28.5 years. Lip strength was compared to radiographic cephalometric measurements. Allelic and genotypic frequencies from polymorphisms rs678397 and rs1815739 in ACTN3 and rs10850110 in MYO1H were compared to each variable. Chi-square and Fisher exact tests were used to determine if differences were statistically significant (alpha = 0.05).

RESULTS

The data showed significant differences between rs678397 genotype and allele frequencies and SNA angle (P = .01; P = .003, respectively); between rs1815739 allele frequency and SNA angle (P = .01); between rs678397 allele frequency and ANB angle (P = .049); between rs678397 genotype and allele frequencies and lip strength in females (P = .045; P = .02); and between rs678397 allele frequency and overall lip strength (P = .049), after mean strength values used as cut off being customized by sex.

CONCLUSIONS

Polymorphisms in ACTN3 are associated with weak lips and larger SNA and ANB angles.