Phenotypes of Enamel Hypomineralization and Molar Incisor Hypomineralization in Permanent Dentition: Identification, Quantification and Proposal for Classification.

OBJECTIVES: To report the extent, pattern, clinical presentation and phenotypes of enamel hypomineralization in permanent dentition Study Design: This cross sectional observational study recruited a random sample of 1726, 12-16 year olds. Enamel hypomineralization was scored on all teeth by a calibrated examiner using the EAPD 2003 criteria. Proportions of affected subjects (prevalence) with a minimum of one hypomineralization and Molar Incisor Hypomineralization (MIH) were calculated. Proportions of following phenotypes were quantified i.e. MH (only FPM hypomineralization), M+IH (concomitantly affected FPMs and permanent incisors without affecting any other tooth in the arch), MIHO (hypomineralization affecting at least one of the canines, premolars or 2(nd) molars and simultaneously including at least one FPM), IH (only permanent incisor's hypomineralization) and NoFPM (hypomineralization affecting at least one of the canines, premolars and 2(nd) molars but not FPM; incisors can be affected concomitantly). A comparative evaluation of extent and severity of enamel hypomineralization was performed amongst various phenotypes. Statistical measures employed t-test, chi square tests and ANOVA. RESULTS: Overall prevalence of affected subjects was 13.21% (228/1726) and 9.79% (169/1726) for enamel hypomineralization and MIH respectively. A total of 4.36+/-3.45 teeth/subject and 6.01+/-5.20 surfaces/subject were found to be affected with enamel hypomineralization. Most prevalent phenotype was M+IH while the least prevalent was IH. Maximum severity i.e. number of affected surfaces and surfaces with PEB were reported for MIHO (p<0.001). CONCLUSION: Enamel hypomineralization can manifest in any tooth in five phenotypic variations in permanent dentition with varying extent and severity.