In vitro longevity of bonding properties of universal adhesives to dentin.

PURPOSE: To evaluate the immediate and 6-month resin-dentin bond strength (muTBS) and nanoleakage (NL) of universal adhesives that contain or do not contain methacryloyloxydecyl dihydrogen phosphate (MDP) and are used in the etch-and-rinse and self-etch strategies. METHODS AND MATERIALS: Forty caries-free extracted third molars were divided into eight groups for muTBS (n=5). The groups were bonded with the Clearfil SE Bond (CSE) and Adper Single Bond 2 (SB) as controls; Peak Universal, self-etch (PkSe) and etch-and rinse (PkEr); Scotchbond Universal Adhesive, self-etch (ScSe) and etch-and-rinse (ScEr); and All Bond Universal, self-etch (AlSe) and etch-and-rinse (AlEr). After composite restorations, specimens were longitudinally sectioned to obtain resin-dentin bonded sticks (0.8 mm(2)). The muTBS of the specimens was tested immediately (IM) or after 6 months of water storage (6M) at 0.5 mm/min. Some sticks at each storage period were immersed in silver nitrate and photo developed, and the NL was evaluated with scanning electron microscopy. Data were analyzed with two-way repeated-measures analysis of variance and Tukey test (alpha=0.05). RESULTS: At the IM period, PkSe and PkEr showed muTBS similar to the control adhesives (p>0.05) but increased NL pattern and lower muTBS after 6M (p<0.05). ScSe and ScEr showed intermediary muTBS values at the IM period but remained stable after 6 months (p>0.05). AlSe showed the lowest muTBS (p<0.05), but muTBS and NL remained stable after 6M (p>0.05). AlEr showed higher IM muTBS but showed higher degradation after 6M (p<0.05). CONCLUSIONS: Universal adhesives that contain MDP showed higher and more stable muTBS with reduced NL at the interfaces after 6 months of water storage.