Effects of a ferric chloride primer on collagen-depleted dentin bonding between tri-n-butylborane initiated self-curing resin and dentin

This study was designed to evaluate the micro-tensile bond strength between a carboxylic resin and dentin, when the dentin surface was modified with an experimental dentin primer. The three primers tested were ED primer II (ED), 0.3% ferric chloride aqueous solution (FE), and ED containing 0.3% ferric chloride (ED/FE). Three commercial dentin conditioners [40% phosphoric acid, 10% NaOCl, and 10% citric acid with 3% ferric chloride (10-3)] were also used. The coronal surfaces of extracted human molars were ground flat to dentin. The dentin surfaces were treated with phosphoric acid, NaOCl, or with one of the primers. The 10-3 was used without phosphoric acid or NaOCl as a control. A composite material rod was bonded to the dentin surface with 4-META/MMA-TBB resin. After 24-h immersion in 37°C distilled water, 0.9 mm x 0.9 mm composite-dentin beams cut from the bonded specimens were stressed to failure in tension at 0.6 mm/min. The bond strengths were also evaluated after 5000 thermocycles. The bond strength of the group ED/FE was significantly higher than those of the 10-3, ED, and FE. After 5000 thermocycling, 10-3, ED and FE showed significant decrease in bond strength, although no significant decrease was seen for ED/FE. It was concluded that dentin surface treatment with phosphoric acid, NaOCl, and the ED/FE primer improved the bonding (p < 0.05) between 4-META/MMA-TBB resin and dentin, with or without thermocycling, while the bond strengths in the control group fell 34% following 5000 thermocycles.