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Background: Molar incisor hypomineralization (MIH) is a qualitative, demarcated enamel defect of hypomineralization affecting one to four first permanent molars, often with incisor involvement. Its etiology is complex. However, evidence suggests the influence of genetic factors, potentially including the single nucleotide polymorphisms (SNPs) rs2889956, rs4811117 and rs13058467, which were previously linked to MIH in a genome-wide association study of German children. The aim was to replicate analyses of possible associations between the SNPs and molar incisor hypomineralization in Polish children., Methods: The final study group consisted of 778 children aged 126-168 months old. Saliva samples were taken, and genomic DNA was extracted and genotyped using beadchip microarrays., Results: Among the 778 subjects, there were 68 (8.7%) subjects with MIH and 710 (91.3%) subjects without MIH. There were no significant differences in distributions in age, sex, or the frequency of caries in permanent dentition between the MIH and non-MIH groups. The rs2889956, rs4811117, and rs13058467 genotype distributions in the studied group conformed to the expected Hardy-Weinberg equilibria, and there were no significant differences in the distributions of their alleles or genotypes between the MIH and non-MIH groups., Conclusion: Our replication study did not confirm highly significant associations between the single nucleotide polymorphisms rs2889956, rs4811117, and rs13058467 with molar incisor hypomineralization in Polish children.

(1) Background: The incidence of ankyloglossia is 0.02-10.7%. Its effect on selected dysfunctions has been described; however, no studies report its impact on several disorders in a group of subjects. The aim of this study was to assess the effect of ankyloglossia on swallowing, speech, occlusion and periodontium. (2) Methods: The study group consisted of 86 patients with ankyloglossia, and the control group (n = 86) had a normal tongue frenulum. Type of swallowing, tongue mobility, speech, occlusion and periodontium were assessed. (3) Results: Ankyloglossia pertained to 75.6% patients with infantile swallowing and 41.3% patients with mature swallowing. Limited tongue mobility was found in 29.4% subjects with moderate ankyloglossia and 70.6% subjects with severe ankyloglossia. All subjects with mild ankyloglossia and all the controls had normal tongue mobility. The relationship between dysglossia and ankyloglossia severity was statistically significant. Malocclusion or crowding was diagnosed in 62% subjects with ankyloglossia and 21.6% subjects in the control group. No periodontal abnormalities were found in any subject. (4) Conclusions: (1) A short tongue frenulum negatively influences swallowing and is associated with an "infantile swallowing pattern". (2) Moderate or severe ankyloglossia significantly limits tongue mobility. (3) A short tongue frenulum negatively influences speech. (4) Ankyloglossia is associated with higher prevalence of malocclusion.