Effect of Pulse-delay Curing on in Vitro Wall-to-wall Contraction of Composite in Dentin Cavity Preparations

Purpose: To determine the effect of pulse-delay curing of resin composite on marginal gap formation in dentin cavity preparations.

Materials And Methods: Cylindrical cavities were prepared in extracted human molar dentin and were distributed into 8 groups (A-H). The cavity preparations were treated with a dentin-bonding agent (Prime & Bond NT) and filled with a light-cured resin composite (Z100). The restorations were irradiated initially for 1, 2 or 3 seconds at a power density of 425 mW/cm2. Following water storage for varying time intervals, the restorations were re-exposed for 10 seconds at 750 mW/cm2. Marginal gap formation was measured by light microscopy after 20 minutes of water-storage, and the wall-to-wall contraction was calculated as the widest gap in percent of cavity diameter.

Results: Pulse-delay curing in combination with a waiting time of at least 1 minute between exposures reduced wall-to-wall contraction in dentin cavities compared to continuous-cure control.