Effect of UVA-activated riboflavin on dentin bonding

Recent studies have reported collagen cross-linking after exposure to riboflavin followed by ultraviolet-a (uva) exposure. this study is the first to investigate the effect of a riboflavin-containing primer on adhesive interface stability and dentinal matrix metalloproteinase activity. human dentin was etched with 35% phosphoric acid,treated with 0.1% riboflavin,exposed to uva for 2 min,and bonded with a two-step etch-and-rinse adhesive. adhesive was applied to control specimens without riboflavin/uva. specimens were subjected to microtensile bond strength tests and pulled to failure after storage for 24 hrs,6 mos,or 1 yr. interfacial nanoleakage was evaluated by light and transmission electron microscopy. to investigate dentinal matrix metalloproteinase activity,we performed correlative zymographic assays on protein extracts obtained from phosphoric-acid-etched dentin powder with or without riboflavin/uva treatment and xp bond. ultraviolet-activated riboflavin treatment increased the immediate bond strength to dentin at all aging intervals (p < 0.05 vs. control) and decreased interfacial nanoleakage in aged specimens (1 yr; p < 0.05). zymograms revealed that riboflavin/uva pre-treatment inhibited dentinal matrix metalloproteinase activity (especially mmp-9). in conclusion,dentinal collagen cross-linking induced by riboflavin/uva increased immediate bond strength,stabilized the adhesive interface,and inhibited dentin matrix metalloproteinases,thereby increasing the durability of resin-dentin bonds. © 2011 international & american associations for dental research.