Molar incisor hypomineralization in the permanent dentition of patients with unilateral or bilateral cleft lip and palate versus controls

Purpose: Molar Incisor Hypomineralization (MIH) is a congenital defect of unknown etiology that has been recently identified and is currently considered an increasing concern to dental clinicians. The defect involves enamel mineralization of one to four permanent first molars usually associated with similarly affected permanent incisors. The purpose of this retrospective study was to investigate the prevalence, severity, and location of MIH in the permanent molars and incisors of patients with unilateral and bilateral cleft lip and palate (CLP) as compared with controls. Methods: The sample consisted of intra-oral photographs of 71 CLP patients which were divided into two groups (unilateral versus bilateral cleft) and a modified Weerheijm ranking of enamel defects was compared to a control sample of 60 children without CLP who were age matched. Pearson chi-square tests were used to compare the groups for differences in the presence of hypomineralization, and Mantel-Haenszel chi-square tests were used to compare the groups for differences in MIH scores. Cochran-Mantel-Haenszel chi-square tests for stratified categorical data were used to compare the cleft and non-cleft sides for differences in the prevalence of hypomineralization and MIH scores within the CLP unilateral subjects. Significance was defined as p<0.05. Results: MIH scores were significantly lower for controls than for CLP bilateral and CLP unilateral groups (p<.0001). CLP bilateral had significantly higher MIH scores than CLP unilateral (p ≤ 0.01). The MIH scores were not significantly different between the cleft and non-cleft sides in the CLP unilateral subjects. However, two of the individual teeth – the maxillary-lateral (p=0.03) and maxillary central incisors (p ≤ 0.01) did show significantly higher scores for the cleft side as compared with the non-cleft side. Conclusions: Cleft patients are at higher risk of MIH than controls and children with bilateral clefts present with the most severe hypomineralization. Correspondence to: Katherine Kula, Department of Orthodontics and Oral Facial Genetics, Indiana University School of Dentistry, 1121 W. Michigan St., Indianapolis, IN 46202, Tel: 317-278-9915; E-mail: [email protected]