Influence of the bonder on the adhesion of porcelain to machined titanium as determined by the strain energy release rate

Objective To determine the adhesion at the titanium–porcelain interface using a fracture mechanics approach, and to investigate the bonding mechanism using SEM. Methods Specimens of five different titanium–porcelain and one base metal–porcelain bonding systems were prepared for a four-point bending interfacial delaminating test on a universal testing machine. The pre-cracked specimen was subjected to load and the strain energy release rate (G, J/m2) was calculated from the critical load to induce stable crack extension in each system. The interface for the various materials was investigated in an SEM and compared. Results The titanium–porcelain with Gold Bonder showed the highest G-value (72.39 ± 13.21 J/m2) among the groups whilst titanium–porcelain with cross-cut-bur preparation showed the lowest (5.78 ± 1.39 J/m2). The former was significantly higher than that of Wiron®99 (base-metal, BEGO, Germany) porcelain (40.01 ± 6.67 J/m2), a clinically accepted bonding system for many years. The G-values of porcelain fused to titanium-Rocatec, titanium-sandblasted and/or titanium-GC-Bonder were 10.81 ± 1.49, 12.64 ± 3.01 and 35.74 ± 5.20 J/m2, respectively. SEM images of the interface fracture crack path for the different bonders enabled the mechanisms responsible for the differences in strain energy release rates to be appreciated. Conclusion The strain energy release rate (G) of titanium–porcelain with a Gold Bonder interface layer was highest among the five different systems.