Dilaceration in the root formation of the upper second premolar.

The upper second premolars are often known to be interfered with the normal development of their roots by the periapical disturbance of the precursor and its adjacent teeth and, in some cases, by the position of floor of the maxillary sinus. This phenomenon called dilaceration is usually characterized by a crease or bend at the junction of the crown and root [1]. In our 10-year consecutive survey of about 300 school children relative to their teeth, we encountered two cases among the accumulated data which revealed abnormal eruptive processes. These two cases, having gone through similar eruptive interferences, succeeded in final eruption more or less normally. However, while the dilaceration of the root was observed in the one, normal root formed itself in the other. Difference between the two could be accounted for by the respective positions of root formations and presence or absence of an oppresive force exerted by the approximal tooth which interfered with normal root formation.