One-year stability of resin-dentin bonds created with a hydrophobic ethanol-wet bonding technique.
Dentin bonding performed with hydrophobic resins using ethanol-wet bonding should be less susceptible to degradation but this hypothesis has never been validated.


OBJECTIVE
This in vitro study evaluated stability of resin-dentin bonds created with an experimental three-step BisGMA/TEGDMA hydrophobic adhesive or a three-step hydrophilic adhesive after one year of accelerated aging in artificial saliva.


METHODS
Flat surfaces in mid-coronal dentin were obtained from 45 sound human molars and randomly divided into three groups (n=15): an experimental three-step BisGMA/TEGDMA hydrophobic adhesive applied to ethanol (ethanol-wet bonding-GI) or water-saturated dentin (water-wet bonding-GII) and Adper Scotchbond Multi-Purpose [MP-GIII] applied, according to manufacturer instructions, to water-saturated dentin. Resin composite crowns were incrementally formed and light-cured to approximately 5mm in height. Bonded specimens were stored in artificial saliva at 37 degrees C for 24h and sectioned into sticks. They were subjected to microtensile bond test and TEM analysis immediately and after one year. Data were analyzed with two-way ANOVA and Tukey tests.


RESULTS
MP exhibited significant reduction in microtensile bond strength after aging (24h: 40.6+/-2.5(a); one year: 27.5+/-3.3(b); in MPa). Hybrid layer degradation was evident in all specimens examined by TEM. The hydrophobic adhesive with ethanol-wet bonding preserved bond strength (24h: 43.7+/-7.4(a); one year: 39.8+/-2.7(a)) and hybrid layer integrity, with the latter demonstrating intact collagen fibrils and wide interfibrillar spaces.


CONCLUSIONS
Coaxing hydrophobic resins into acid-etched dentin using ethanol-wet bonding preserves resin-dentin bond integrity without the adjunctive use of MMPs inhibitors and warrants further biocompatibility and patient safety's studies and clinical testing.
Sadek
Fernanda T
FT
Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil.
Castellan
Carina S
CS
Braga
Roberto R
RR
Mai
Sui
S
Tjäderhane
Leo
L
Pashley
David H
DH
Tay
Franklin R
FR
D003188:Composite Resins; D003442:Crowns; D001840:Dental Bonding / Q000379:methods*; D003763:Dental Leakage; D003799:Dental Stress Analysis; D003804:Dentin; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000737:chemistry; D000431:Ethanol; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D046529:Microscopy, Electron, Transmission; D019279:Resin Cements / Q000737:chemistry; D013718:Tensile Strength; D013997:Time Factors; D014867:Water
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements; D014867:Water; D000431:Ethanol