Shear bond strength of resin cements to human dentin.
OBJECTIVE
The objectives of this in vitro study were (1) to assess the bond strength of the universal cement RelyX Unicem to dentin and to compare it with three conventional resin cements, (2) to test the influence of aging on their bonding capacity and (3) to test the influence of the operator on bonding quality by performing the same test in two different centers.


METHODS
160 third molars, divided into 80 for tests at the University of Zurich (Z) and 80 for tests at the University of Berne (B), were assigned to 2 x 8 subgroups of 10 teeth each. The specimens were prepared with the corresponding bonding agents and acrylic rods were luted either with RelyX Unicem (U), RelyX ARC (A), Multilink (M) or Panavia 21 (P). All specimens were stored in water for 24h (W) and half of the specimens were subjected to 1500 cycles of thermocycling (5 degrees C and 55 degrees C) (T). Bond strength was measured by means of a shear test.


RESULTS
After water storage RelyX Unicem exhibited lowest bond strength (UWZ: 9.2+/-1.6 MPa, UWB: 9.9+/-1.2 MPa, AWZ: 15.3+/-6.0 MPa, AWB: 12.2+/-4.3 MPa, MWZ: 15.6+/-3.3 MPa, MWB: 12.4 MPa+/-2.4, PWZ: 13.4+/-2.9 MPa, PWB: 14.9+/-2.6 MPa). Thermocycling affected the bonding performance of all four cements. However, bond strength of RelyX Unicem was least influenced by thermocycling (UTZ: 9.4+/-2.9 MPa, UTB: 8.6+/-1.3 MPa, ATZ: 11.4+/-6.3 MPa, ATB: 13.3+/-3.7 MPa, MTZ: 15.4+/-3.1 MPa, MTB: 10.3+/-2.4 MPa, PTZ: 11.1+/-2.8 MPa, PTB: 11.3+/-2.8 MPa).


CONCLUSIONS
Although the bond strength of RelyX Unicem to dentin was lower in comparison to RelyX ARC, Multilink and Panavia 21, its bond strength was less sensitive to variations in handling and aging.
Holderegger
Claudia
C
Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland.
Sailer
Irena
I
Schuhmacher
Caroline
C
Schläpfer
Ragna
R
Hämmerle
Christoph
C
Fischer
Jens
J
D000180:Acrylic Resins / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D008422:Materials Testing; D010710:Phosphates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; C093719:Panavia TPN-S; D010710:Phosphates; D011109:Polymethacrylic Acids; C483701:Rely X Unicem; C462240:RelyX ARC; D019279:Resin Cements; C502351:multilink adhesive system; D014867:Water; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate