Prevalence of hypodontia and other developmental dental anomalies in children with or without molar incisor hypomineralisation

Objectives: To investigate whether hypodontia and other developmental dental anomalies were more common in children with MIH than their unaffected peers, and to determine if sex or geographical location had any effect on hypodontia prevalence. Methods: This analytical cross-sectional study was conducted in specialist paediatric dentistry clinics across 14 countries, categorised into six geographical regions. A total of 1279 children (aged 6- 17 years) underwent a clinical examination and were allocated to the MIH (n = 649) or comparison group (n = 630). A validated MIH index was used to record the presence/extent of any hypomineralisation and a standardised approach was used to establish the clinical and/or radiographic presence of ten developmental dental anomalies. Results: Four anomalies were significantly more prevalent in participants with MIH than those without this condition: hypodontia (p = 0.047), dens invaginatus (p = 0.004), dens evaginatus (p < 0.001) and microdont maxillary lateral incisors (p = 0.01). Additionally, the adjusted odds of hypodontia were 1.49 times higher in children with MIH compared to those without MIH. There was considerable disparity between geographic locations with the highest prevalence of hypodontia in participants from the Western Pacific region (11.21 %) and the lowest (2.92 %) in the Americas. No statistically significant association was found between sex (male vs. female) and hypodontia (p = 0.839). Conclusions: Accepting that the study group may not be representative of the wider population, the findings still have important clinical relevance. Furthermore, they lend support to the concept of shared genetic and epigenetic influence in the aetiology of MIH and other developmental dental disorders.