Bond Strength Between Veneer Porcelains and CAD/CAM Ceramic to Titanium

Objectives:   The aim of this study was to evaluate the bond strength of three different veneering porcelains fired on CP Titanium and a CAD/CAM ceramic cemented to CP Titanium. 

Methods:  sixty-four bars of CP Titanium grade II (8x 3x 0.5 mm) were divided randomly into four groups: Group 1 Titankeramic (Vita Zahnfabrik), 2 Triceram (Dentaurum), 3 Initial Ti (GC), and Group 4 MKII blocks (Vita). Each veneer porcelain (groups 1-3) was applied with dimensions limited to 8x3x1mm and fired on CP Ti bars following the manufacture’s instructions and ISO 9693 recommendations. Group 4, Vita Mark II blocks were sectioned into sixteen bars (8x3x1mm) and cemented with Multilink Implant cement (Ivoclar) on CP Ti bars. Fifteen Specimens from each group were tested for bond strength by Schwickerath crack initiation test (ISO/DIS 9693) using an Instron machine; the mode of failure and bond interface was evaluated by SEM/EDS, N =15. 

Results: Bond Strength of Veneer Porcelain and MKII to CP Ti.

Group	Bond Strength ( MPa)	Significant Difference
Group 1: Titankeramik/CP Ti	22.3 ± 8.5	A
Group 2: Triceram/CP Ti	16.6 ± 9.9	AB
Group 3: Initial Ti/CP Ti	10.0 ± 6.9	B
Group 4: Mark II CP Ti	59.0 ± 17.7	C

The data was analyzed statistically using ANOVA and Tukey at p< 0.5. Groups with the same letter are not significantly different. Group 4 is significantly higher than the other groups. Group 1 is significantly higher than group 3, but similar to group 2. SEM/EDS analysis reveals that the mode of failure for groups 1 - 3 are a mixture of adhesive, mixed, and cohesive failures. 

Conclusions:  Cementing a milled ceramic to CP Ti produces bond strength significantly greater than conventional veneering porcelains.