The lingual cusp of tooth #29 has fractured. When restoring it, which occlusal relationship must be re-established?

Correct answer: D. Centric contact of the cusp tip in the opposing fossa

• A. BALANCING-side (non-working) contacts should be ABSENT in a natural dentition — they are destructive interferences, not a target to reproduce. Bilateral balanced occlusion is a goal only in complete dentures.
• B. The description of a distal fossa contacting an opposing cusp ridge does not correspond to the cusp–fossa relationship required for this cusp.
• C. PROTRUSIVE movement is guided by the ANTERIOR teeth. In a correctly organised occlusion, posterior teeth should DISCLUDE in protrusion, so this is not the relationship that governs a premolar cusp restoration.
• D. CORRECT. The lingual cusp of a mandibular second premolar is a NON-SUPPORTING (non-centric) cusp, but the restoration must still reproduce the correct CENTRIC RELATIONSHIP — the cusp tip seating into the corresponding FOSSA of the opposing tooth in maximum intercuspation, giving a stable, axially directed contact. Restoring the cusp too tall creates a deflective contact and pain on closure; restoring it short leaves an unstable occlusion, allows drifting and overloads the remaining supporting cusps.

Note: Check the restoration in all excursions, not just in maximum intercuspation: centric contacts stable and axially directed, then confirm no working or non-working interference in lateral excursion and posterior disclusion in protrusion.