Lee Hyo-Seol, Kim Soo-Hyun, Kim Seong-Oh, Choi Byung-Jai, Cho Sung-Won, Park Wonse, Song Je Seon
Department of Pediatric Dentistry, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
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.
Oral Surg Oral Med Oral Pathol Oral Radiol. 2015 May;119(5):544-52. doi: 10.1016/j.oooo.2014.10.013. Epub 2014 Nov 7.
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.
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.
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.
The results of the present study imply that MIM-affected molars probably result from inappropriate differentiation of the apical pulp and dental follicle.
磨牙-切牙畸形（MIM）是一种新发现的牙齿异常类型，涉及恒牙第一磨牙的特征性牙根畸形。本研究的目的是揭示MIM牙齿的微观结构，以确定其起源。
从一名9岁女孩口中拔除了4颗因严重松动的MIM牙齿。通过微计算机断层扫描（micro-CT）、苏木精和伊红（H&E）染色、免疫组织化学染色以及扫描电子显微镜检查来确定牙齿的详细微观结构，以揭示其详细的微观结构。
Micro-CT和H&E染色显示牙髓底部由三层组成：上层、中层和下层。在牙髓底部的中层观察到无定形硬组织和活跃细胞，这些细胞对牙本质涎蛋白和骨钙素呈阳性染色，但对Ⅻ型胶原呈阴性染色。
本研究结果表明，受MIM影响的磨牙可能是由于根尖牙髓和牙囊的分化不当所致。
