Curing dental materials is not as simple as just turning on the light. Distance and light intensity do make a difference. MJ
Acta Odontol Scand. 2014 Feb;72(2):113-9. doi: 10.3109/00016357.2013.805431. Epub 2013 Jul 3.
Abstract Objectives. To assess the influence of light-curing unit tip distance on the microtensile bond strength (μTBS) and nanoleakage of self-etching adhesives to enamel and dentin. Materials and methods. Flat buccal surfaces were prepared on 198 bovine incisors. The teeth were randomly assigned into nine groups for μTBS (n = 8) and nanoleakage (n = 3) testing according to the adhesive system (Clearfil Protect Bond, Clearfil Tri-S Bond or One Up Bond F Plus) and distance from the light-curing tip (0, 3 or 6 mm). The bonded samples were tested in tension (0.5 mm/min) and nanoleakage was analyzed using SEM. Results. Clearfil Protect Bond exhibited the highest tensile strength on both enamel and dentin. Leakage was higher in samples exposed at a distance of 6 mm on enamel and 0 mm on dentin. One Up Bond F Plus experienced the greatest amount of nanoleakage on both substrates. Conclusions. Light-curing unit distance did not influence the μTBS of the adhesives, but nanoleakage increased on enamel samples when photoactivation occurred at a distance of 6 mm.