Effect of laboratory procedures and thermocycling on the shear bond strength of resin-metal bonding systems.
BACKGROUND
During fabrication or repair of removable partial dentures, resin-to-metal or resin-to-denture tooth bonds may be stressed by laboratory procedures.


OBJECTIVE
The purpose of this in vitro study was to evaluate the effect of steam cleaning, boiling, ultrasonic cleaning (laboratory procedures), and thermocycling on shear bond strength of resin bonds to metal and denture teeth.


METHODS
Resin-metal bonding systems and their specific veneer resins (Rocatec, Sinfony; Rocatec, Visio-Gem, HLC-BOND, Zeta LC and Ducera experimental veneer resin) were tested on a Co-Cr alloy (Wirobond C). The veneer resins were bonded to resin denture teeth. The experimental groups (n=7) were subjected to the following conditions: 24-hour storage of the specimens in air (group I, control group), storage in air and treated with simulated laboratory procedures (2 minutes steam cleaning, 15 minutes ultrasonic cleaning at room temperature, 1 hour boiling in water, group II), storage in air with thermocycling (5000 cycles, 5 degrees to 55 degrees C, group III), storage in air with laboratory procedures followed by thermocycling (group IV), and storage in air with thermocycling followed by laboratory procedures (group V). Shear strength tests (MPa) were performed with a universal testing machine until fracture. After shear bond testing, the failure mode of the resin-metal and resin-denture tooth bonds was assessed. Statistical analysis of the results was carried out with one-way analysis of variance and Bonferroni-Dunn's multiple comparisons post hoc analysis for test groups (alpha=0.05).


RESULTS
Except for Ducera/denture tooth specimens (groups III to V: 8.7 +/- 3.4-9.1 +/- 1.7; 10.8 +/- 1.9 MPa control group), the Wirobond C and denture tooth specimens (groups III, IV and V: 1.4 +/- 0.9-11.9 +/- 2.3 MPa), showed significantly lower shear bond strengths than the corresponding control groups (7.5 +/- 2.9-21.0 +/- 3.4 MPa, P<.05). The shear bond strengths of group II of Sinfony/Wirobond C (11.6 +/- 3.3 MPa, P<.0001), Visio-Gem/Wirobond C (7.4 +/- 1.9 MPa, P<0.0001), Ducera/Wirobond C (11.8 +/- 2.9 MPa, P<.0001) and of Zeta/denture tooth (3.9 +/- 1.6 MPa, P=.0005) were significantly decreased by steam, boiling, and ultrasonic procedures compared with the corresponding control groups (21.0 +/- 3.4 MPa; 14.7 +/- 4.0 MPa; 19.1 +/- 2.3 MPa; 7.5 +/- 2.9 MPa, respectively). No significant differences were noted among groups III, IV, and V. Co-Cr specimens subjected to the Rocatec system and bonded with Sinfony and HLC BOND/Zeta specimens showed cohesive failure. Adhesive failure was observed for the experimental veneer resin on the Co-Cr specimens and for all veneer resins on the denture teeth.


CONCLUSIONS
Simulation of laboratory procedures and thermocycling caused a significant drop in shear bond strength of metal-resin and denture tooth-resin bonds for most of the tested veneer resins. Thermocycling before shear testing had the same effect on veneer resin bond strength as the simulated laboratory procedures.
Kim
Joon-Young
JY
School of Oral Medicine, University of Cologne, Germany.
Pfeiffer
Peter
P
Niedermeier
Wilhelm
W
D000180:Acrylic Resins / Q000737:chemistry*; D000388:Air; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003832:Denture, Partial, Removable; D006358:Hot Temperature; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D013227:Steam; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics; D014093:Tooth, Artificial; D014465:Ultrasonics
D000180:Acrylic Resins; D002858:Chromium Alloys; D003188:Composite Resins; D003722:Dental Alloys; D003738:Dental Cements; D008689:Methacrylates; D011140:Polyurethanes; C076811:Rocatec; C477352:Sinfony composite resin; D013227:Steam; C046981:ESPE Visio-Gem; C029824:urethane dimethacrylate luting resin; D017438:Bisphenol A-Glycidyl Methacrylate; D019904:Polymethyl Methacrylate