The Art of Retention:Understanding Clasps in Removable Orthodontic Appliances

Clasps are an essential part of removable orthodontic appliance design, providing the retention needed to keep an appliance securely in place. Different clasp designs can be selected depending on the teeth available, the amount of undercut, and the level of retention required. Understanding the design and function of each clasp helps ensure that the appliance remains both effective and comfortable for the patient.

Adam’s Clasp

The Adam’s clasp is composed of two arrowheads connected together with a bridge. The bridge is positioned at a 45-degree angle to the long axis, while the two arms engage the mesial and distal proximal undercuts (Inman, 2008).

Adam’s clasps provide good retention and are relatively easy to fabricate (Mansuri & Singh, 2014). Partially or fully erupted primary and permanent molars can be engaged using Adam’s clasps (Inman, 2008).

Several modifications of the Adam’s clasp have also been reported in the literature, including an Adam’s clasp with a J-hook, an incorporated helix, a distal extension for engaging elastics, or an Adam’s clasp with a soldered buccal tube for extraoral anchorage (Mansuri & Singh, 2014).

Southend Clasp

The Southend clasp is mainly used on anterior teeth because it requires only a minimal undercut (Stephens, 1979). The wire should follow the curvature of the gingival margin of the teeth (Mansuri & Singh, 2014).

It can be used when the upper incisors are not proclined (Stephens, 1979).

Triangular Clasp

The triangular clasp is a small triangular clasp that engages the proximal surface undercut between two teeth (Broussard, 1981).

Triangular clasps are generally used in addition to existing clasps when additional retention is required (Mansuri & Singh, 2014). It has also been reported that their use does not lead to gingival trauma (Mansuri & Singh, 2014).

Ball-End Clasps

Ball-end clasps consist of stainless-steel wires with a ball structure at one end. This ball end engages the proximal undercut between adjacent posterior teeth, providing additional retention for the appliance (Mansuri & Singh, 2014).

C Clasp

The C clasp engages the buccocervical undercut. The wire extends from the proximal undercut, follows along the cervical margin, and is carried over into a lingual arm.

It has a simple design and is easy to fabricate (Mansuri & Singh, 2014). However, the tooth needs to be fully erupted for the clasp to be used effectively (Mansuri & Singh, 2014).

Patient Instructions

For removable appliances to function effectively, patients should follow the recommended instructions for wearing and maintaining them:

• The patient must wear the appliance at all times except during oral hygiene practices (NHS, 2019).

• The appliance can be worn during eating and sleeping but should be removed during sports or swimming (NHS, 2019).

• The appliance should be stored in a protective box to prevent accidental loss or damage (NHS, 2019).

• The appliance should be cleaned daily with toothpaste and a small, soft-bristle toothbrush to prevent attrition of the acrylic plate (NHS, 2019).

References

• Broussard, G.J. and Broussard Garfford, J., 1981. *Orthodontic appliance and clasp therefor*. U.S. Patent 4,273,530.

• Inman, D.P. and Inman Donal, P., 2008. *Clasp for removable dental appliances*. U.S. Patent Application 11/845,920.

• Mansuri, M. and Singh, V.P., 2014. Clasps in removable orthodontics. *Journal of Nobel Medical College*, 3(1), pp.1–9.

• Stephens, C.D., 1979. The Southend clasp. *British Journal of Orthodontics*, 6(4), pp.183–185.