Improved wear resistance in a restorative material is MOST closely associated with:

Correct answer: B. A smooth, well-polished surface finish

• A. A higher resin fraction REDUCES wear resistance — the polymer matrix is the soft, wear-prone phase. Higher FILLER loading improves wear resistance.
• B. CORRECT. Wear resistance rises with SURFACE SMOOTHNESS. A rough surface presents projecting asperities that concentrate stress and are sheared away under occlusal and abrasive loading, and roughness also accelerates wear of the OPPOSING tooth or restoration. A well-polished surface distributes load evenly, retains less plaque and stain, and resists degradation. Smaller, more densely packed filler particles permit a smoother finish, which is why microfilled and nanofilled composites polish better than macrofilled materials.
• C. Water sorption causes hygroscopic expansion and plasticizes the matrix, DEGRADING mechanical properties including wear resistance.
• D. Larger filler particles produce a rougher surface: as the matrix wears, large particles pluck out and leave voids, accelerating wear and abrading the opposing dentition.

Note: Polishing is not merely cosmetic. A smooth surface reduces wear, plaque retention, staining and secondary caries risk — it is a clinical outcome, not a finishing courtesy.