What opposes the retentive arm?

What opposes the retentive arm?

• A. Occlusal rest
• B. Reciprocal arm
• C. Guiding plate
• D. Clasp terminus

Answer: (B)

The main idea is that a clasp’s action is counterbalanced by a reciprocal component to protect the adjacent tooth and stabilize the denture. The retentive arm grips the undercut of the tooth to hold the denture in place. The part that opposes this action is the reciprocal arm, which sits on the tooth surface opposite the retentive arm and provides a counterforce. This reciprocal contact distributes the lateral forces generated when the retentive arm engages undercut, helping to prevent tipping or torque on the tooth. The other options don’t serve this opposing, stabilizing role. An occlusal rest provides vertical support to resist occlusal dislodgement, not lateral opposition to the retentive arm. A guiding plate helps direct movement or indirect retention, not oppose the retentive force. The clasp terminus is simply the end of the retentive arm that engages the undercut, not the opposing stabilizing surface.

The main idea is that a clasp’s action is counterbalanced by a reciprocal component to protect the adjacent tooth and stabilize the denture. The retentive arm grips the undercut of the tooth to hold the denture in place. The part that opposes this action is the reciprocal arm, which sits on the tooth surface opposite the retentive arm and provides a counterforce. This reciprocal contact distributes the lateral forces generated when the retentive arm engages undercut, helping to prevent tipping or torque on the tooth.

The other options don’t serve this opposing, stabilizing role. An occlusal rest provides vertical support to resist occlusal dislodgement, not lateral opposition to the retentive arm. A guiding plate helps direct movement or indirect retention, not oppose the retentive force. The clasp terminus is simply the end of the retentive arm that engages the undercut, not the opposing stabilizing surface.