Hyo-Seol Lee1, Soo-Hyun Kim1, Seong-Oh Kim2, Byung-Jai Choi2, Sung-Won Cho3, Wonse Park4, Je Seon Song5. 1. Department of Pediatric Dentistry, College of Dentistry, Yonsei University, Seoul, Republic of Korea. 2. Department of Pediatric Dentistry, College of Dentistry, Yonsei University, Seoul, Republic of Korea; Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Republic of Korea. 3. Division in Anatomy & Developmental Biology, Department of Oral Biology, College of Dentistry, Yonsei University, Seoul, Republic of Korea. 4. Department of General Dentistry, College of Dentistry, Yonsei University, Seoul, Republic of Korea. 5. Department of Pediatric Dentistry, College of Dentistry, Yonsei University, Seoul, Republic of Korea; Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Electronic address: Songjs@yuhs.ac.
Abstract
OBJECTIVE: Molar-incisor malformation (MIM) is a newly discovered type of dental anomaly that involves a characteristic root malformation of the permanent first molars. The aim of this study was to reveal the microstructure of MIM teeth in order to determine their origin. STUDY DESIGN: Four MIM teeth were extracted from a 9-year-old girl due to severe mobility. The detailed microstructure of the teeth was determined by examinations with micro-computed tomography (micro-CT), hematoxylin and eosin (H&E) staining, immunohistochemical staining, and scanning electron microscopy to reveal the detailed microstructure. RESULTS: Micro-CT and H&E staining revealed the pulpal floor comprising three layers: upper, middle, and lower. Amorphous hard tissues and hyperactive cells were observed in the middle layer of the pulpal floor, and the cells stained positively for dentin sialoprotein and osteocalcin, but not for collagen XII. CONCLUSION: The results of the present study imply that MIM-affected molars probably result from inappropriate differentiation of the apical pulp and dental follicle.
OBJECTIVE: Molar-incisor malformation (MIM) is a newly discovered type of dental anomaly that involves a characteristic root malformation of the permanent first molars. The aim of this study was to reveal the microstructure of MIM teeth in order to determine their origin. STUDY DESIGN: Four MIM teeth were extracted from a 9-year-old girl due to severe mobility. The detailed microstructure of the teeth was determined by examinations with micro-computed tomography (micro-CT), hematoxylin and eosin (H&E) staining, immunohistochemical staining, and scanning electron microscopy to reveal the detailed microstructure. RESULTS: Micro-CT and H&E staining revealed the pulpal floor comprising three layers: upper, middle, and lower. Amorphous hard tissues and hyperactive cells were observed in the middle layer of the pulpal floor, and the cells stained positively for dentin sialoprotein and osteocalcin, but not for collagen XII. CONCLUSION: The results of the present study imply that MIM-affected molars probably result from inappropriate differentiation of the apical pulp and dental follicle.