Method: Forty-nine children (6-9 years) were clinically examined by visual inspection and data were compiled at baseline, 6 and 12 months using MIH severity (European Academy of Paediatric Dentistry criteria) and caries experience (DMFT index - WHO criteria). Parents completed questionnaire about socioeconomic factors. All patients received preventive therapy and restorative treatment.
Result: At baseline, MIH was considered mild in 32.7% (n=16) and severe in 67.3% (n= 33) of children. There was no significant difference of the severe MIH in relation to gender (p=0.181), age (p=0.190) and family income (p=0.263) by Chi-Square test. Among patients with mild diagnosis, only 12.5% had caries lesion. However, 100% of patients with severe MIH presented DMFT > 0 (p<0.00). At 6 months, of 14 patients remained with mild MIH, only 4 change to severe (p=0.125, McNemar test). Most of the changing pattern of MIH severity was associated to brown demarcated opacity that had enamel breakdown in molars and caries lesion was present. At 12 months there was no change related to severity (p=1.00).
Conclusion: Increase in MIH severity showed a close correlation with dental caries experience during the study period.