Alternative cingulum rest seat.

M axillary canines and incisors often lack an adequate cingulum to allow for a conventional cingulum rest preparation (Fig. 1). Cingulum rests on mandibular canines have often not been used because of the perception that there is not adequate thickness of enamel in the rest region. This has recently been refuted in research by Rossi,’ who found that if the rest seats are prepared on mandibular canines “in the middle third of the crown length, then the average depth of preparation would be well within the confines of the enamel thickness.” This article describes an alternative cingulum rest seat design (Fig. 2) to that of the conventional “inverted V” described for use with teeth having a prominent cingulum.* It is also recommended for use on surveyed crowns.