Objective: To evaluate if genetic polymorphisms in the oestrogen receptor 1 ( ESR1) and oestrogen receptor 2 ( ESR2) genes encoded for oestrogen receptors alpha (ERα) and beta (ERβ) are involved in permanent tooth size. Design: Cross-sectional study. Setting: Orthodontic Clinic at School of Dentistry of Ribeirão Preto, University of São Paulo. Participants: A total of 108 orthodontic patients. Materials and Methods: Pre-treatment orthodontic records were evaluated. Dental casts were used to determine the maximum crown measurements of fully erupted permanent teeth in the mesiodistal dimensions. Second and third molars were not included in the analysis. Genomic DNA samples were used for the genotyping of four genetic polymorphisms: ESR1 (rs9340799 and rs2234693) and ESR2 (rs1256049 and rs4986938). The associations between tooth size and sex were evaluated using t test. The associations between tooth size and genotype were analysed with linear regression and adjusted by sex at an alpha of P⩽0.05. Results: Female patients presented smaller tooth size than male patients. A statistically significant difference was observed in almost all teeth ( P<0.05). The genetic polymorphisms in rs9340799, rs2234693, rs1256049 and rs4986938 were associated with some tooth sizes in both the maxilla and mandible ( P<0.05). Conclusion: This study provides evidence that genetic polymorphisms in ESR1 and ESR2 could be associated with tooth size in permanent teeth.

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Objectives To explore whether variations in odontogenesis-related genes are associated with tooth-size discrepancies. Materials and Methods Measurements of the width of permanent teeth were obtained from dental casts of 62 orthodontic patients (age 15.65 ± 6.82 years; 29 males and 33 females). Participants were classified according to the anterior and overall Bolton ratios as without tooth-size discrepancy or with maxillary or mandibular tooth-size excess. Genomic DNA extracted from buccal cells was used, and 13 single nucleotide polymorphisms (SNPs) across nine genes were genotyped by polymerase chain reaction using TaqMan chemistry. χ2 or Fisher exact tests were applied to determine the overrepresentation of genotypes/alleles depending on the type of tooth-size discrepancy (α = .05; corrected P value: P &lt; 5.556 × 10−3). Odds ratios (ORs) and their correspondent 95% confidence intervals (CIs) were also calculated to investigate the risk of this phenotype for the SNPs having significant association. Results Individuals carrying the FGF10 rs900379 T allele were more likely to have larger mandibular teeth (OR = 3.74; 95% CI: 1.65–8.47; P = .002). This effect appeared to be stronger when two copies of the risk allele (TT) were found (recessive model, OR = 6.16; 95% CI: 1.71–22.16; P = .006). On the other hand, FGF13 rs5931572 rare homozygotes (AA, or male A hemizygotes) had increased risk of displaying tooth-size discrepancies when compared with the common homozygotes (GG, or male G hemizygotes; OR = 10.32; 95% CI: 2.20–48.26; P = .003). Conclusions The results suggest that FGF10 and FGF13 may contribute to the presence of tooth-size discrepancies.