Proportion and extent of manifestation of molar-incisor-hypomineralizations according to different phenotypes.

OBJECTIVE: This epidemiological study aimed to assess the proportion and extent of manifestation of enamel hypomineralization, including molar-incisor-hypomineralization (MIH), in the permanent and primary dentition. METHODS: A total of 693 children enrolled in an ongoing birth cohort study (GINIplus-10) were examined at their 10-year follow-up. Enamel hypomineralization was scored in the primary and permanent dentition on a tooth- and surface-related level based on the criteria of the European Academy of Paediatric Dentistry (EAPD). Children were grouped according to their distribution pattern of enamel hypomineralization: children with a minimum of one hypomineralized tooth in the primary dentition (ht ≥ 1) and permanent dentition (HT ≥ 1); with a minimum of one hypomineralization on at least one first permanent molar (MIH); and with hypomineralization on at least one first permanent molar and permanent incisor (M + IH). For each group, the mean values of hypomineralized primary teeth (ht), permanent teeth (HT), and permanent surfaces (HS) were calculated. RESULTS: The proportion of affected children was 36.5 percent (HT ≥ 1), 14.7 percent (MIH), and 9.4 percent (M + IH); 6.9 percent of the subjects had a minimum of one affected primary tooth (ht ≥ 1). The mean number of hypomineralized permanent teeth and surfaces were 2.3HT/2.9HS (HT ≥ 1), 3.4HT/4.8HS (MIH), and 4.2HT/5.9HS (M + IH). The mean number of hypomineralized primary teeth amounted to 0.1ht in the entire study population. CONCLUSIONS: Enamel hypomineralization can be detected frequently in this study sample. Children with M + IH showed the highest number of affected teeth and surfaces followed by those with MIH.

Genome-wide association study (GWAS) for molar-incisor hypomineralization (MIH).

OBJECTIVES: This genome-wide association study (GWAS) investigated the relationship between molar-incisor hypomineralization (MIH) and possible genetic loci. Clinical and genetic data from the 10-year follow-up of 668 children from the Munich GINI-plus and LISA-plus birth cohort studies were analyzed. MATERIAL AND METHODS: The dental examinations included the diagnosis of MIH according to the criteria of the European Academy of Paediatric Dentistry (EAPD). Children with MIH were categorized as those with a minimum of one hypomineralized first permanent molar. A GWAS was implemented following a quality-control step and an additive genetic effect was assumed. RESULTS: A total of 2,013,491 single-nucleotide polymorphisms (SNPs) were available for analysis. Rs13058467, which is located near the SCUBE1 gene on chromosome 22 (p < 3.72E-7), was identified as a possible locus linked to MIH when using a threshold of p value <1E-6. CONCLUSIONS: After considering the limitations of the present study (e.g., limited sample size and lack of an independent replication sample), it can be concluded that (1) replication analyses in an independent cohort study are strongly recommended and (2) large-scale and well-powered studies are needed to investigate a possible genetic link to MIH.

Is there a positive relationship between molar incisor hypomineralisations and the presence of dental caries?

OBJECTIVE: This epidemiological study aimed to compare the caries experience in 10-year-olds with and without molar incisor hypomineralisation (MIH). METHODS: About 693 children from an ongoing birth cohort study (GINIplus10) were examined for caries lesions to determine the DMF index. Furthermore, enamel hypomineralisation (EH) was scored on all permanent teeth/surfaces, according to the criteria of the European Academy of Paediatric Dentistry. Children with EH were categorised into those with a minimum of one EH in the permanent dentition (MIH/1), with EH on at least one-first permanent molar (MIH/1A), on at least one-first permanent molar and permanent incisor (MIH/1B), and on other permanent teeth (MIH/1C). RESULTS: The mean caries experience was 0.4 (SD 0.9) DMFT. Existence of MIH/1, MIH/1A, MIH/1B, and MIH/1C was determined in 36.5%, 14.7%, 9.4%, and 21.8% of all children. The corresponding DMFT values were the following: no MIH: 0.3 (SD 0.8); MIH/1: 0.5 (SD 0.9); MIH/1A: 0.5 (SD 0.9); MIH/1B: 0.4 (SD 0.9); and MIH/1C: 0.4 (SD 0.9) DMFT. No significant differences were found between all groups. CONCLUSIONS: There was no relationship between the presence of EH/MIH and caries in 10-year-olds. A ratio of one EH-associated defect to two caries lesions indicates that both conditions are prevalent and influence the oral health status of 10-year-old children from Munich, Germany.