Prosthodontics & Occlusion · patient case question
What is the MAIN FUNCTION of a precision attachment?
Patient case: Denosumab, Kennedy Class I RPD with a precision attachment on #21
Scenario: Patient with OSTEOPOROSIS taking DENOSUMAB. Kennedy Class I with a PRECISION ATTACHMENT on tooth #21. The chief complaint involves MOBILITY TYPE 3; the COLD TEST WAS NEGATIVE but the tooth was SENSITIVE TO PERCUSSION. A periapical shows one crown carrying the attachment system, bone resorption to the MIDDLE THIRD of the root, and an inflamed (not infected) periodontal ligament.
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Correct answer: A. Retention
Precision attachments provide primarily RETENTION (resistance to dislodgement along the path of insertion) by engaging matrix and patrix components. They also improve esthetics (no visible clasps) but their main mechanical role is retention.
- A. Correct. A precision (intracoronal) attachment is a direct retainer — its primary function is RETENTION, resisting vertical dislodgement of the prosthesis away from the tissues.
- B. Support is resistance to VERTICAL displacement TOWARD the tissues, provided by rests on abutments and by the denture-bearing mucosa and bone.
- C. Resistance is a preparation-geometry term from fixed prosthodontics (resistance form), not a function of an attachment.
- D. Stability is resistance to HORIZONTAL/lateral displacement, provided mainly by rigid major connectors, guide planes and bracing arms.
Note: This same question appeared on Day 1 — it is clearly a favourite. Retention = away from tissue; Support = toward tissue; Stability = lateral.
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