Abstract
As the root of the deciduous incisor is very close to its successor, trauma of the deciduous incisor easily affects the tooth formation of the permanent successor. This is a case report of arrested root formation in an upper right permanent central incisor subsequent to trauma to a deciduous predecessor.
A boy aged 5 years 9 months fell down from a bight of 2 meters and his upper deciduous central incisors were struck. The left one fell of and the right one was intruded. The intruded incisor reerupted after 2 months and spontaneously fell off 7 months after reeruption.
At the age of 7 years, the left permanent incisor erupted, but the right one did not. On the X-ray film the root of the right incisor was slightly developed on the distal side only. The right incisor erupted after surgical exposure of its crown. At the age of 8 years 9 months, he clashed against his friend and the right incisor was hit. The right one was fractured at the tooth neck and was extracted. According to the histopathological findings, there was much displastic dentin and cellular cementum inside the crown dentin and predentin, and the pulp cavity was very narrow. In the displastic dentin of the palatal side, the normal root dentin was noted. It suggested that the developping root was broken to the crown and this was caused by trauma, while the root formation of this tooth was arrested.
