Effect of chromium interlayer on the shear bond strength between porcelain and pure titanium

This study evaluated the effect of a chromium interlayer deposited by electroplating on the shear bond strength between titanium and porcelain.

Seventy specimens of machined commercially pure titanium (CP Ti) plates grade II (10 mm x 10 mm x 1 mm) were prepared. The specimens were divided into three groups according to the concentration of electroplating solution, Gr I (control without electroplating, n=10), Gr II (5%, w/v, of chromium nitrate solution, n=30) and Gr III (10%, w/v, of chromium nitrate solution, n=30). Groups II and III were further divided into three subgroups (n=10) according to the electroplating time (0.5, 1 and 2 h). Two titanium-porcelains (Vita Titankeramik and Triceram) were applied to each subgroup (n=5). The titanium-porcelain interfaces were loaded under shear in a universal testing machine (crosshead speed: 0.5 mm/min) until failure occurred. Failure types were examined with stereomicroscope and the titanium-porcelain interface examined by SEM. Data were analyzed using ANOVA and Tukey's test.

Bond strength values were significantly affected by the type of electroplating treatment (P<0.05), but not by the type of porcelain (P>0.05). The CP Ti/Vita Titankeramik (0.5 h, 10%, w/v) and the CP Ti/Triceram (0.5h 5%, w/v) groups showed the highest bond strength (MPa) (26.72+/-5.78 and 25.48+/-4.14) respectively among the groups. Stereomicroscope and SEM images showed that chromium interlayer enhanced the bond strength between porcelain and titanium.

Bond strength between porcelain and CP Ti can be improved by the use of chromium interlayer prior to porcelain firing.