Association between molar incisor hypomineralisation and tooth agenesis: a cross-sectional study in Brazilian children and adolescents

The aim of the present was to assess the association between MIH and tooth agenesis (TA) in orthodontic patients from the Federal University of Rio Grande do Norte, Natal, Brazil.

A cross-sectional study was performed to evaluate the presence of MIH and TA in a sample of 371 pretreatment orthodontic records from patients aged 9–18 years. Statistical analyses were performed using the Chi-square and Fisher’s exact tests, and logistic regressions.

There was a statistically significant association between the prevalence of tooth agenesis and MIH. A higher percentage of third molar agenesis, maxillary premolar agenesis, and mandibular second premolar agenesis was observed among children with MIH-affected teeth. Patients with MIH had a 2.43 times greater chance of third molar agenesis, and a 5.88 times higher likelihood of mandibular premolar agenesis.

There is a weak association between MIH and TA. Furthermore, the presence of hypomineralised molars increases the risk of tooth agenesis.