Curing Light Distance Effect — NDEB AFK MCQ
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Correct answer: B — Increasing the distance between the light tip and the composite reduces the light intensity reaching the material, potentially causing incomplete polymerisation at depth
Light intensity reaching the composite surface follows the inverse square law — doubling the distance reduces the intensity to approximately one-quarter. The curing light tip should be positioned as close as possible to the composite surface (ideally 0-1 mm) to maximise energy delivery. Maintaining adequate intensity (minimum 400 mW/cm²) and exposure time is essential for complete polymerisation. Inadequate curing results in reduced mechanical properties, increased monomer release, poor colour stability, and increased marginal leakage.
Reference: Anusavice – Phillips' Science of Dental Materials, 13th ed., 2022