Exploring the association between genetic and environmental factors and molar incisor hypomineralization: evidence from a twin study

• Published in: International journal of paediatric dentistry Vol. 28; no. 2; pp. 198 - 206
• Main Authors: Teixeira, Rafael José Pio Barbosa, Andrade, Natália Silva, Queiroz, Lisanca Carvalho Cavalcante, Mendes, Fausto Medeiros, Moura, Marcoeli Silva, Moura, Lúcia de Fátima Almeida de Deus, Lima, Marina Deus Moura
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-03-2018
• Subjects: Adolescent; Brazil - epidemiology; Child; Cross-Sectional Studies; Dental enamel; Dental Enamel Hypoplasia - epidemiology; Dental Enamel Hypoplasia - etiology; Dental Enamel Hypoplasia - genetics; Dentistry; Diagnosis; Diseases in Twins - epidemiology; Diseases in Twins - etiology; Diseases in Twins - genetics; Environmental factors; Etiology; Female; Hemorrhage; Heredity; Humans; Incisors; Male; Mineralization; Molars; Pregnancy; Prevalence; Risk Factors; Socioeconomic Factors; Surveys and Questionnaires; Teeth; Twin studies; Twins; Twins, Dizygotic - statistics & numerical data; Twins, Monozygotic - statistics & numerical data
• ISSN: 0960-7439; 1365-263X
• DOI: 10.1111/ipd.12327

Background
The etiology of molar‐incisor hypomineralization (MIH) remains unknown. Studies indicate that it is multifactorial, and that genetic and environmental factors are involved. Research with twins provides important subsidy to investigate the Influence of genetics and environmental factors that act during pregnancy on the etiology of alterations.
Aim
This cross‐sectional study evaluated the agreement of molar incisor hypomineralization (MIH) between monozygotic and dizygotic twin pairs and the association with environmental factors.
Design
The sample consisted of 167 pairs of twins (8–15 years old), 94 monozygotic and 73 dizygotic. The parents answered a questionnaire on sociodemographic data and pre‐, peri‐, and postnatal health. A dental examination was performed by two calibrated examiners (Kappa ≥0.88) for MIH diagnosis, following the criteria proposed by the European Academy of Pediatric Dentistry in 2003.
Results
The prevalence of MIH was 29.3%. There was greater concordance of MIH between monozygotic twins for affected first molars and permanent incisors (P = 0.0012) and pairs of twins assessed (P = 0.0211). The presence of MIH was associated with family income between one and two wages (P = 0.009, prevalence ratio [PR] = 3.82, confidence interval [CI 95%] 1.40–10.44), above two wages (P = 0.007, PR = 4.60, 95% CI: 1.51–14.05), and gestational hemorrhage (P = 0.032, PR = 5.70, 95% CI: 1.16–28.14).
Conclusions
The greater concordance in the diagnosis of MIH among monozygotic twins indicates a genetic influence, although environmental factors, such as family income and hemorrhage during pregnancy, are also associated with the occurrence of MIH.