Abstract
A rare case is presented in which a congenitally missing primary canine, an abnormally formed primary first molar and an impacted supernumerary premolar were found in the same lower left quadrant. The patient was a Japanese girl aged 2 years and 10 months. After 4 years of observation, when the girl was 6 years 2 months old, the abnormal first primary molar and the impacted supernumerary tooth were extracted to avoid disturbance of the developing lower first premolar. The extracted teeth were examined microscopically. The first primary molar seemed to be a fusion of a normal first primary molar with a small coronal tooth. Thus the supernumerary premolar seemed to be a successor of the coronal tooth. When the patient was 8 years 1 month old, the lower left permanent canine began to erupt; its shape was normal.
