Demonstration of "vertical barrelling" using profilometry.

The aim of this study was to demonstrate the extent of tooth flexure under axial loading using profilometry. Fifteen extracted human permanent upper premolar teeth were embedded in hard die stone and divided into 3 groups. One group was left unprepared, the second group had artificial cervical saucer shaped lesions prepared and the final group had artificial cervical notch lesions prepared. The labial profile was taken using a diamond stylus mounted in a Profilometer. The teeth were then loaded in an axial direction to circa 670 N and the labial surface re-profiled 20 s after loading. The results indicate that changes occur in the labial profile of premolar teeth that are subjected to axial loading which could be considered to represent vertical barrelling. Changes in the profile of the artificial saucer and notch lesions prepared at the cervical region suggest that stresses would be generated on restorations of these lesions.