Association between molar-incisor hypomineralisation and occlusal alterations in children

To investigate the association between MIH and occlusal alterations in children with mixed dentition.

Orthodontic records of children aged 8 to 12 years were evaluated in this cross-sectional study. Patients with craniofacial syndromes or anomalies and records with insufficient image quality were excluded. MIH was diagnosed according to the European Academy of Paediatric Dentistry (EAPD) criteria. Occlusal alterations were assessed using criteria adapted from the Dental Aesthetic Index (DAI). Intra-examiner reliability was assessed. Associations were analysed using Chi-square or Fisher's exact tests, and crude prevalence ratios (PR) with 95% confidence intervals were calculated.

A total of 391 children aged 8 to 12 years were included, with an MIH prevalence of 12.3%. Posterior crossbite (24.6%) and lower arch crowding (65.5%) were among the most frequent occlusal alterations. No statistically significant associations were observed between MIH and the evaluated occlusal variables. However, severe MIH was associated with posterior crossbite (PR = 1.43; 95% CI 1.04-1.96). Among the individual clinical features of MIH, only atypical caries lesions were associated with posterior crossbite (PR = 2.17; 95% CI 1.01-4.68).

MIH was not associated with occlusal alterations in children with mixed dentition. However, severe MIH and atypical caries lesions were associated with posterior crossbite, suggesting that the clinical expression of MIH may be more relevant than its presence alone in relation to specific occlusal manifestations.