Sinoguchi K, Saga Y, Ogichi H
Department of Pediatric Dentistry, School of Dentistry, Hokkaido University.
Shoni Shikagaku Zasshi. 1991;29(1):167-73.
A 7-year old boy visited the dental hospital complaining that the upper left second deciduous molar had not erupted. Radiographs showed that the crown of this tooth existed near the apex of the upper left first molar. Inversion of the second deciduous molar and second premolar was definite. There were no differences in location, size and shape between the left and right second premolars. A tooth-like object was observed near by the germ of the left second premolar. The impacted molar was examined histopathologically after extraction and consequently it was found that it was a supernumerary tooth. New radiographs were made which suggested that the succedaneous premolar developed normally. The tooth germ of the primolar develops on the lingual side of the deciduous molar and moves in the level of the occlusal plane of the primary molar. Later they are found between the divergent roots and, at the end of the pre-eruptive phase, below the roots of the primary molars. We concluded that the supernumerary tooth disturbed this adjustment.
一名7岁男孩前往牙科医院就诊，主诉左上第二乳磨牙未萌出。X光片显示该牙冠位于左上第一磨牙根尖附近。第二乳磨牙和第二前磨牙倒置情况明确。左右第二前磨牙在位置、大小和形状上无差异。在左第二前磨牙牙胚附近观察到一个类牙物体。拔除阻生磨牙后进行组织病理学检查，结果发现它是一颗多生牙。新拍的X光片显示继承前磨牙发育正常。乳磨牙的牙胚在乳磨牙舌侧发育，并在乳牙咬合平面水平移动。之后它们出现在分叉牙根之间，在萌出前期结束时，位于乳牙牙根下方。我们得出结论，多生牙干扰了这种调整。
