INFLUENCE OF LIGHT-INTENSITY ON 2 RESTORATIVE SYSTEMS

Objectives: High intensity curing lights are recommended almost univer sally on the basis of immediate curing depth measurements. Although th is single factor is well documented, the influence of light intensity on other parameters has not been investigated extensively. Methods: Tw o restorative systems were examined with two light intensities in rega rd to four properties; polymerization shrinkage (density method), flex ural modulus and strength (ISO 4049), hardness profiles after post-cur e (Vickers), and marginal adaptation in dentine cavities (quantitative margin analysis). Results: The variation in light intensity did not s ignificantly affect curing contraction or post-cure hardness profiles to a depth of 4.5 mm for either resin composite. Significant differenc es were found in flexural modulus with both restoratives; only one mat erial demonstrated a light intensity-related influence on flexural str ength. Marginal gap formation increased in each bonding agent/resin co mposite pair with increased light intensity. Conclusion. In clinically relevant layer thicknesses, curing a resin composite with a higher in tensity light may demonstrate significant disadvantages due to increas ed shrinkage stress.