Effect of thermocycling on bond strength of luting cements to zirconia ceramic.
OBJECTIVE
The aim of this study was to evaluate the shear bond strength of different cements to densely sintered zirconia ceramic after aging by thermocycling.


METHODS
The following luting cements for bonding ZrO2-TZP (tetragonal zirconia polycrystals) were used in this study: Ketac-Cem, Nexus, Rely X Unicem, Superbond C&B, Panavia F, and Panavia 21. Groups of 30 test specimens were prepared by bonding stainless steel cylinders tribochemically silica-coated with the Rocatec-system to sandblasted ZrO2-TZP ceramic disks (cercon smart ceramics). Prior to testing all bonded specimens were stored in distilled water (37 degrees C) for 48 h and half of them (n=15) were additionally aged by thermocycling (10,000 times).


RESULTS
None of the fractures occurred at the interface of the metallic rods. The assemblies failed either at the interface between the ceramic surface and the cements or within the cements. Thermocycling affected the bond strength of all luting cements studied except for both Panavia materials and Rely X Unicem.


CONCLUSIONS
Within the limits of this in vitro study the results showed that-after thermocycling-bond strengths for Ketac-Cem and Nexus were quite low. Nexus in combination with tribochemical silica-coating of ceramic surface produced a higher bond strength. The four adhesive resin cements (Rely X Unicem, Superbond C&B, Panavia F, and Panavia 21) gave superior results. The strongest bond to zirconia was obtained with Panavia 21.
Lüthy
Heinz
H
Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Center for Dental and Oral Medicine, University of Zurich, Plattenstrasse 11, CH-8032 Zurich, Switzerland. heinz.luethy@unibas.ch
Loeffel
Olivier
O
Hammerle
Christoph H F
CH
D001896:Boron Compounds / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003461:Crystallography; D003722:Dental Alloys / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008277:Magnesium Oxide / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics; D013997:Time Factors; D015034:Zinc Oxide / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
D001896:Boron Compounds; D003722:Dental Alloys; D003738:Dental Cements; D005899:Glass Ionomer Cements; D008689:Methacrylates; D008768:Methylmethacrylates; C433206:Nexus; C093719:Panavia TPN-S; C438843:Panavia-Fluoro; D010710:Phosphates; D011076:Polycarboxylate Cement; C483701:Rely X Unicem; D019279:Resin Cements; C076811:Rocatec; D013193:Stainless Steel; D008277:Magnesium Oxide; D012822:Silicon Dioxide; C040235:Ketac-cem; C049495:Super-bond; D015040:Zirconium; C028541:zirconium oxide; D015034:Zinc Oxide