The effect of a ceramic coating on the cpTi-porcelain bond strength

Objectives. To investigate the bond strength between cpTi and low fusing porcelains after different treatments. Methods. 72 patterns were covered with a ceramic coating and invested with phosphate-bonded material (group A), another 72 were invested with magnesia material (group B) and all cast with cpTi. 31 solid castings were selected from each group. The castings of group B were ground and sandblasted, while the castings of group A were only sandblasted. Aluminum content of the metal surface was determined by EDS and castings were submitted to a 3-point bending test to determine the modulus of elasticity (E). The porcelains Duceratin Plus, Noritake Ti22 and Triceram were applied respectively and specimens were submitted to a 3-point bending test. The fracture mode and the remaining porcelain were determined by optical microscopy and SEWEDS. Bond strength and fracture mode were calculated by two-way ANOVA. Results. The E of groups A and B was 98.3 GPa and 98.6 GPa respectively. The bond strength was 26 +/- 3 MPa (Duceratin Plus), 28 +/- 13 MPa (Noritake Ti22), 27 +/- 2 MPa (Triceram) for group A and 24 +/- 1 MPa, 29 +/- 12 MPa, 27 +/- 1 MPa for group B respectively. No significant differences were found for the same porcelain between the two groups (p < 0.05). A significant difference was found between Duceratin Plus and Noritake Ti22, for group B (p<0.05). The mode of failure was mainly adhesive for all specimens. A significant reduction in aluminum was recorded in all subgroups. Significance. The special coating of patterns makes the Ti casting procedure inexpensive, without reducing the metal-ceramic bond strength. (c) 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.