Spontaneous changes in the rotation of premolar teeth from eruption until the established dentition.

The aim of this study was to investigate whether the rotation of teeth changed from the point of eruption until the established dentition. The first 50 cases with adequate records enrolled in the Belfast Growth Study were selected, and the premolar rotation was measured at the point of eruption and again at age 15 in the established dentition. All premolars in a quadrant with early loss of the deciduous predecessors, early loss of the first permanent molars or absence of premolars, were disregarded. The results showed that the second premolars in both the upper and lower arches which erupted rotated had a tendency to improve over the observed period. Upper and lower first premolars which erupt rotated show the same tendency to improve, but to a lesser extent and less frequently than the second premolars. There seemed to be cases where a premolar deteriorated over the period, especially the first premolars.