Microtensile bond strength of two-step etch-and-rinse adhesive systems on sound and artificial caries-affected dentin.
OBJECTIVE
To evaluate the microtensile bond strength of two-step etch-and-rinse adhesive systems on sound and artificial caries-affected dentin (CAD) produced by in vitro monoculture of Streptococcus mutans.


METHODS
10 recently extracted non-carious human third molars were ground to expose a flat dentin surface. Each tooth was sectioned through the long axis with a diamond saw to create two similar halves. One half was used as control (sound dentin - SD) while the other was submitted to caries lesion induction in vitro, using 40 mL of Brain Heart Infusion broth containing 1% sucrose and 40 microL of Streptococcus mutans UA159 inoculum (final bacterial concentration: 1-2 x 105 CFU/mL). The specimens were incubated at 37 degrees C for 4 weeks, and the culture medium was changed every 3 days for 4 weeks. Sound or CAD were alternatively restored as follow (n = 5): Single Bond 2/sound dentin (SB-SD); Single Bond 2/artificial caries-affected dentin (SB-CAD); Prime&Bond NT/sound dentin (PB-SD); and Prime&Bond NT/CAD (PB-CAD).The adhesives were applied to dentin according to manufacturers' instructions, and build-ups of resin composite (Filtek Z250) were prepared and polymerized with a LED light-curing unit (Radii). The restored teeth were stored in distilled water at 37 degrees C for 24 hours and thereafter sectioned perpendicular to the bonded interface with a refrigerated low-speed diamond saw, obtaining three slices per half-tooth (n = 15). The microtensile bond strength (microTBS) test was performed in a universal test machine with a crosshead speed of 1 mm/minute. Bond strengths were calculated in MPa and analyzed by Kruskal-Wallis and Student-Newman-Keuls at a 0.05 level of significance. Failure patterns were examined with an optical microscope.


RESULTS
SD produced significantly higher microTBS values than CAD for both adhesive systems. Furthermore, independently of the dentin condition, Single Bond 2 had higher values than Prime Bond NT (P < 0.05). Single Bond 2 showed higher microTBS than Prime Bond NT, in both substrates, and application to CAD reduced the adhesion.
Zanchi
César Henrique
CH
Department of Operative Dentistry, Federal University of Pelotas, School of Dentistry, Rio Grande do Sul, Brazil.
Lund
Rafael Guerra
RG
Perrone
Luciana Rodrigues
LR
Ribeiro
Gládis Aver
GA
del Pino
Francisco Augusto Burkert
FA
Pinto
Márcia Bueno
MB
Demarco
Flávio Fernando
FF
D000096:Acetone; D000134:Acid Etching, Dental; D017438:Bisphenol A-Glycidyl Methacrylate; D001840:Dental Bonding; D003731:Dental Caries; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D000431:Ethanol; D006801:Humans; D008422:Materials Testing; D011109:Polymethacrylic Acids; D019279:Resin Cements / Q000737:chemistry; D013718:Tensile Strength
D017220:Dentin-Bonding Agents; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C115612:single bond; D000096:Acetone; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate