Where is the last 1/3 of the retentive arm of the clasp located?

The last third of the retentive arm of the clasp is positioned apical to the height of contour. This placement is critical for ensuring that the clasp effectively engages the tooth and provides the necessary retention for the prosthesis. When the retentive arm extends apically beyond the height of contour, it allows for a proper undercut, which aids in holding the partial denture securely in place against the forces that might dislodge it during function.

This design is fundamental in removable partial denture frameworks, as a clasp that is correctly positioned will optimize support and retention while also preventing excessive stress on the natural tooth. Understanding the anatomy and positioning of the clasp arms in relation to the height of contour is essential for effective prosthetic design and function.