Interfacial shear strengths of dental resin-glass fibers by the microbond test.
OBJECTIVE
The aim of this study was to investigate the feasibility of using the microbond test (MBT) to probe the durability of the bond between a polymerized dental resin with differently silanized E-glass fibers.


METHODS
The E-glass fibers were silanized with equivalent amounts of two types of acrylic-silane coupling agents: 3-methacryloxypropyltrimethoxysilane (MPTMS) and 10-methacryloxydecyltrimethoxysilane (MDTMS), a more hydrophobic silane coupling agent than MPTMS. Unsilanized E-glass fibers were used as the control. Microdroplets of a photo-activated dental resin were applied on the fiber and photocured with visible light irradiation (470 nm). Subsequently, the specimens were tested in shear after 24h storage in air at 23 degrees C or water at 60 degrees C.


RESULTS
The mean interfacial shear strength (tau) and the standard deviation in MPa for the three systems in 23 degrees C in air (n>7) were: 33.8(10.1), 33.7(8.9) and 15.3(4.2) for the MPTMS silanized, MDTMS silanized, and unsilanized fibers, respectively. When the three types of fibers were first exposed to 60 degrees C water for 24h prior to having the microdroplets of the resin bonded to them, the strength values of the MDTMS silanized fibers and the control fibers remained essentially unchanged at (n> or =7) 31.8(7.7) and 17.5(4.9)MPa respectively; the MPTMS specimens showed a significant decrease to 15.8(4.8)MPa. Similar trends were observed when the fibers had microdroplets of the resin bonded to them prior to aqueous exposure.


CONCLUSIONS
These results indicate that the microbond test has the sensitivity to measure changes at the interface between polymerized dental resins and variously silanized E-glass fibers. It appears that surface modification of the fibers with the more hydrophobic silane coupling agent MDTMS promotes enhanced resistance to degradation from exposure to water. The microbond test has the potential for studying dental adhesion involving small bonded areas under a variety of conditions with different adhesive systems and substrates.
McDonough
W G
WG
National Institute of Standards and Technology, Polymers Division, 100 Bureau Drive, Stop 8543, Gaithersburg, MD 20899, USA. walter.mcdonough@nist.gov
Antonucci
J M
JM
Dunkers
J P
JP
D003188:Composite Resins; D001840:Dental Bonding; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005240:Feasibility Studies; D005898:Glass; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing / Q000379:methods*; D008689:Methacrylates / Q000737:chemistry*; D015203:Reproducibility of Results; D012821:Silanes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013718:Tensile Strength
C443707:10-methacryloxydecyltrimethoxysilane; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D012821:Silanes; C009753:fiberglass; C017492:methacryloxypropyltrimethoxysilane