Influence of aging treatments on microtensile bond strength of adhesive systems to primary dentin.
OBJECTIVE
The purpose of this study was to evaluate the in vitro influence of aging treatments on the microtensile bond strength of 2-step total-etch and self-etch adhesive systems to primary dentin.


METHODS
Class I cavities (4 mm x 4 mm x 2 mm) were prepared in 80 extracted human primary molars divided into 8 groups (N=5) per adhesive system: (1) Single Bond (SI); and (2) Clearfil SE Bond (SE). Restored teeth were exposed to individual and combined aging treatments: (1) thermal (2,000 x at 5-55 degrees C; T); (2) mechanical load (100,000 x 80 N; M); (3) pH (mineralizing/demineralizing solutions; pH); and (4) control (24-hour water storage; C). Beam-shaped microtensile specimens were prepared (0.8 mm2 cross-sectional area) and loaded at a crosshead speed of 1.0 mm/minute in a universal testing machine. Fracture modes were examined by scanning electron microscope.


RESULTS
Means (MPa) and standard deviations (+/-) were: (1) SI-T=24.17 (+/-1.99); (2) SI-M=25.64 (+/-9.75); (3) Si-pH=23.43 (+/-4.19); (4) SI-C=33.81 (+/-2.45); (5) SI-TM=18.60 (+/-3.57); (6) SI-TpH=23.90 (+/-4.28); (7) SI-MpH=20.96 (+/-4.06); (8) SI-TMpH=20.94 (+/-3.15); (9) SE-T=24.08 (+/-4.52); (10) SE-M=18.30 (+/-14.12); (11) SE-pH=19.22 (+/-8.93); (12) SE-C=37.80 (+/-7.28); (13) SE-TM=22.89 (+/-11.74); (14) SE-TpH=27.87 (+/-12.77); (15) SE-MpH=18.87 (+/-10.95); and (16) SE-TMpH=22.55 (+/-3.05). Both adhesive systems presented similar dentin bond strength (P>.05) which were significantly reduced when combined aging treatments were applied or when pH cycling (pH) was done.


CONCLUSIONS
Combined aging treatments and also pH cycling alone influenced negatively adhesive bond strengths.
Rocha
Rachel
R
Department of Stomatology, University of Santa Maria, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil. rarocha@usp.br
Soares
Fabio Z M
FZ
Rodrigues
Celia R M D
CR
Rodrigues Filho
Leonardo Eloy
LE
D000134:Acid Etching, Dental / Q000379:methods*; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008963:Molar; D019279:Resin Cements; D012822:Silicon Dioxide; D013314:Stress, Mechanical; D013718:Tensile Strength; D014094:Tooth, Deciduous; D015040:Zirconium
C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C083568:Z100 composite resin; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium