Association between molar-incisor hypomineralisation and dental anomalies.

Background: Common etiological factors have been reported in the development of molar-incisor hypomineralisation (MIH) and dental anomalies (DA).

Aim: To assess the association between MIH and DAs.

Design: A cross-sectional study was performed to evaluate the presence of MIH and other six DAs in a sample of 415 pretreatment records from patients aged 9-18 years. Statistical analyses were performed using the chi-squared and Fisher's exact tests, and logistic regressions.

Results: There was statistically significant association between the prevalence of DAs and MIH (CI: 1.43-2.43, φ-coefficient: 0.204, PR: 1.87). Higher percentage of tooth agenesis (CI: 1.37-1.68, φ-coefficient: 0.271, PR: 1.50), maxillary premolar agenesis (CI: 1.70-3.65, φ-coefficient: 0.125, PR: 2.49), mandibular second premolar agenesis (CI: 1.68-3.16, φ-coefficient: 0.172, PR: 2.30) and distoangulation of the mandibular second premolars (CI: 1.31-3.47, φ-coefficient: 0.103, PR: 2.13) was observed among children who had MIH-affected teeth. Individuals with MIH had a 2.95 times greater chance of having DAs (R = .153). The number of patients with DAs was higher when the first molar showed severe defects (OR = 4.47; R = .149).

Conclusion: There is a weak association between MIH and DAs. Patients with severe MIH lesions have a slightly higher risk of presenting DAs.