The effect of the position and orientation of unerupted premaxillary supernumerary teeth on eruption and displacement of permanent incisors.

The hospital records of 101 consecutive patients admitted for removal of premaxillary supernumerary teeth were examined. From the clinical notes and preoperative anterior occlusal radiographs the following information was noted: the position and orientation of the supernumerary teeth, and whether they caused delayed eruption, rotation or displacement of the associated permanent incisors. There were 140 supernumerary teeth (mean per child = 1.39). Delayed eruption of permanent incisors occurred in 56% of cases. Supernumerary teeth situated between central incisors caused eruption delay infrequently, but were associated with rotation and displacement of permanent incisors more frequently than those that overlapped the incisors on the radiographs. Supernumerary teeth that were orientated vertically caused eruption delay more frequently than those that were inverted, but the orientation of supernumerary teeth did not influence rotation or horizontal displacement of the permanent incisors.