Dental materials: The Adams family

Abstract

Clasps are retentive removable appliance components that work by engaging the areas beneath the most bulbous parts of a tooth, called undercuts. The first orthodontic clasp consisted of a loop of wire that fitted to the buccal gingival margin but the lack of buccal undercuts in teeth that are not sufficiently erupted led to attempts to design a clasp that would use the mesiobuccal and distobuccal undercuts, which are accessible when a tooth is less well erupted. The first such design was introduced by Victor Hugo Jackson in 1906. The Jackson clasp is a simple orthodontic clasp but with squared corners that engage the mesiobuccal and distobuccal undercuts. Next came the Crozat clasp in 1920. Designed by George B. Crozat, it consists of a plain orthodontic clasp with an additional soldered piece of wire that engages the undercuts. This was followed by the arrowhead clasp by Artur Martin Schwarz in 1938 that consists of a series of arrowheads and engages the mesiobuccal and distobuccal undercuts of two adjacent teeth. In 1949 these concepts were largely eclipsed by a design by Charles Philip Adams that dramatically improved the retention of removable appliances and remains the most popular retention component for removable orthodontic appliances. This article gives a review of the Adams clasp and its related components.