Effects of LED curing light on silver diamine fluoride penetration into dentin

This ex-vivo study investigated the effect of a light-emitting diode (LED) curing light on the depth of penetration of Silver Diamine Fluoride (SDF) into carious lesions. Twenty-four primary teeth with untreated caries lesions were allocated into groups and treated within 5 min after extraction: (1) n = 6 treated for 1 min with one drop of SDF followed by 10 sec rinse with tap water, (2) n = 6 treated for 10 sec with one drop of SDF and exposed to LED light for 20 sec (30 sec total SDF exposure) followed by 10 sec rinse with tap water, (3) n = 6 treated for 10 sec with one drop of SDF followed by a 10 sec rinse with tap water, (4) n = 3 untreated, and (5) n = 3 untreated but exposed to LED light for 20 sec. Samples were prepared, embedded, sectioned and silver penetration was measured using backscattered electron imaging in the scanning electron microscope and energy-dispersive X-ray spectroscopy analysis. Results were expressed as the average relative depth of penetration (%) = Ag depth/lesion depth x 100 from 5 sites in each lesion. Group means were compared using mixed model analysis. Mean +/- standard deviation (SD) penetration was: 86.4 +/- 20.7% in Group 1, 94.3 +/- 13.7% in Group 2, and 26.7 +/- 13.9% in Group 3. Groups 1 and 2 were statistically similar and different from Group 3 (p < 0.001). Groups 4 and 5 had no silver present. Use of LED light for 20 sec after 10 sec SDF application appears to facilitate silver penetration, similar to a 1 min SDF application. Clinical studies are needed to define the role of silver penetration in sustained caries arrest.