Retention in a clasp assembly comes from which portion of the tooth?

Retention in a clasp assembly comes from which portion of the tooth?

• A. Cervical third area
• B. Gingival third area
• C. Middle third area
• D. Incisal third area

Answer: (B)

Retention from a clasp comes from engaging an undercut on the tooth. The most reliable undercut for retention is in the gingival third of the crown, near the gingival margin. This region provides a definite undercut depth that a clasp can engage firmly, while staying away from the occlusal/incisal surface and away from causing undue leverage on the tooth during function. It also keeps the clasp away from the edge of the tooth where hygiene or periodontal health could be compromised. The other regions don’t offer as consistent or controllable an undercut for retention: the incisal/occlusal area is not suited for gripping, and the middle third typically has a less favorable contour for stable engagement.

Retention from a clasp comes from engaging an undercut on the tooth. The most reliable undercut for retention is in the gingival third of the crown, near the gingival margin. This region provides a definite undercut depth that a clasp can engage firmly, while staying away from the occlusal/incisal surface and away from causing undue leverage on the tooth during function. It also keeps the clasp away from the edge of the tooth where hygiene or periodontal health could be compromised. The other regions don’t offer as consistent or controllable an undercut for retention: the incisal/occlusal area is not suited for gripping, and the middle third typically has a less favorable contour for stable engagement.