Association between the severity of Molar-Incisor Hypomineralization (MIH) and the Involvement of permanent incisors in schoolchildren

Abstract

Introduction: Molar-Incisor Hypomineralization (MIH) is a qualitative enamel developmental defect affecting one or more permanent first molars and, occasionally, the incisors. Clinically, it is characterized by well-defined opacities of varying color, from white to yellowish-brown, and increased enamel fragility, which can lead to post-eruptive fractures. This condition is relevant in Pediatric Dentistry because it is associated with a higher risk of caries, dentin hypersensitivity, and difficulties in clinical management, as well as aesthetic impact when the incisors are involved. MIH can be classified as mild or moderate/severe, according to the extent of the defect and structural involvement, this classification being important for prognosis and clinical decision-making. Mild MIH is characterized by well-defined opacities with intact enamel and absence of fractures; the moderate/severe form involves extensive opacities, may present post-eruptive fractures, structural involvement, sensitivity, and the need for restorative interventions or even extraction. The involvement of permanent incisors is variable and can generate aesthetic and psychosocial repercussions. However, the association between the severity of molar-incisor hypomineralization (MIH) and the pattern of incisor involvement is not yet well established in the literature. Therefore, this study aimed to evaluate whether there is an association between the severity of MIH and the involvement of permanent incisors in schoolchildren. Objective: To evaluate whether there is an association between the severity of molar-incisor hypomineralization (MIH) and the pattern of involvement of permanent incisors (PI) in schoolchildren with MIH. Methodology: A random and representative sample of schoolchildren from Diamantina-MG was collected; 105 children aged 8 to 12 years with MIH were selected. The inclusion criterion was the presence of MIH and 8 erupted permanent incisors; children with fixed orthodontic appliances were excluded. Two calibrated examiners (kappa>0.80) performed the examinations, using Ghanim's criteria. After tabulating the data, descriptive analyses and the Mann-Whitney test were performed (p<0.05). Results and Discussion: The mean age of the participants was 9.54 (1.47), with 57% being girls and 43% boys. Regarding the severity of MIH, 40 (38.1%) presented mild MIH (white opacities) and 65 (61.9%) presented moderate/severe MIH (yellow/brown opacity and/or post-eruptive fracture/atypical caries/atypical restoration). The number of affected permanent incisors ranged from 0 to 7 with a mean of 1.30 (SD=1.37). No statistically significant association was found between the severity of MIH and the number of affected incisors (p=0.137). The upper central incisors were the most affected (26.7%), followed by the lower central incisors (19%), upper lateral incisors (15.2%), and lower lateral incisors (12.4%). Conclusion: There was no difference between the severity of molar-incisor hypomineralization and the number of permanent incisors affected.