Hypomineralized second primary molars: prevalence, defect characteristics and relationship with dental caries in Melbourne preschool children

Background Dental caries and enamel defects (DDE) are prevalent amongst children. The presence of DDE, especially enamel hypomineralization, may increase caries experience. The reported prevalence of hypomineralized second primary molars (HSPM) is 2.7–21.8%, although the occurrence in Australian children remains unknown. These HSPM represent a potential predictive factor for molar‐incisor hypomineralization (MIH). Methods In total, 623 children aged 3–5 years from 30 randomly selected kindergartens participated. The HSPM were recorded using an index combining the European Academy of Paediatric Dentistry MIH Judgment Criteria and modified DDE Index. Caries was recorded using International Caries Detection and Assessment System criteria. Results In total, 144 HSPM were observed in 88 of the 623 (14.1%) children, a tooth‐level prevalence of 5.8%. The prevalence of dentinal carious lesions was 13.2%, and caries prevalence (d2–6mft > 0) was 36.4%. Cavitated carious lesions affected 30.7% of HSPM. Conclusions The relationship between an increase in HSPM lesion extent and increasing number of HSPM per child was statistically significant. A positive association between HSPM severity and extent at tooth level existed (P