Adhesion of porcelain to titanium and a titanium alloy

Objectives. The objectives of the study were to determine the adhesion at the titanium–porcelain interface using a fracture mechanics approach, and to investigate the bonding mechanism using SEM and X-ray microanalysis. Methods. Specimens of four titanium–porcelain bonding systems were prepared in a rectangular shape for a four-point bending test on a universal testing machine. The pre-cracked specimen was subjected to a limited number of load and partial unload cycles, and the strain energy release rate or interfacial toughness (Gc value) was calculated for each system. The interface was investigated in an SEM, which also enabled quantitative X-ray microanalysis, and comparison with a simulation of an atomically sharp interface to ascertain whether diffusion bonding occurred. Results. The Titanium/Titankeramik® with GoldBonder® bonding system showed the highest Gc value (48.9±12.4 J/m2) among the groups whilst Titanium/Duceratin® showed the lowest (12.9±3.6 J/m2). The former was significantly higher than that of nickel–chromium/porcelain (40.3±4.8 J/m2) from the previous study [Int J Prosthod 12 (1999) 547], which is a clinically accepted bonding system. The Gc values of Titanium/Titankeramik® and Titanium alloy/Titankeramik® were 16.7±2.4 and 27.8±5.3 J/m2, respectively. The X-ray microanalysis suggested that diffusion of some elements has occurred at the interface. Conclusions. The strain energy release rate (Gc-value) of titanium/Titankeramik® with GoldBonder® was highest among the four systems. X-ray microanalysis gave some evidence of diffusion of some elements, particularly of the porcelain into the metal, which may assist the bonding during the firing.