Jie Liu, DDS, PhD,(a) Mitsuru Atsuta, DDS, PhD,(a) and Ikuya Watanabe, DDS, PhD(b)
(a)Division of Fixed Prosthodontics and Oral Rehabilitation, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan, and (b)Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX, USA
Purpose: This study examined the effect of degassing and sandblasting on the three-point flexure bond strength of low-fusing porcelain to cast titanium and compared the results with the strength of porcelain to a gold alloy.
Materials and Methods: Cast titanium plates (0.5 x 5.0 x 25.0 mm) were prepared and the surfaces were sandblasted with three different-sized alumina particles (50, 125, and 250 μm). After sandblasting, the cast plates were divided into two groups: one group to be degassed and the other that was not degassed. A low-fusing porcelain (1.0 x 5.0 x 8.0 mm) was then baked on the center of the cast titanium plate. Conventional gold alloy/porcelain specimens were also prepared as references. Degassing was performed according to heating schedules recommended by the manufacturer. Three-point bending tests were conducted using a universal testing machine at a crosshead speed of 1.5 mm/minute and a distance of 20 mm between the supporting rods. The mean value of the fracture force (N) and the deflections (mm) at fracture were measured.
Results: The degassed specimens withstood significantly (p<0.05) greater force to fracture and deflection compared to the non-degassed specimens for each corresponding alumina particle size. However, there were no statistical differences in force to fracture and in deflection among the specimens sandblasted with the 50, 125, and 250 μm alumina particles. There was no statistical difference in calculated bond strength between the degassed titanium and the gold alloy.
Conclusion: When a low-fusing porcelain system was used, the three-point flexure bond strength to degassed titanium was comparable to the strength of the porcelain to gold alloy.
(Int Chin J Dent 2002; 2: 67-74.)
Clinical Significance: When a low-fusing porcelain system was used, the reliable titanium-ceramic restorations could be obtained by degassing of titanium under vacuum condition.
Key Words: bond strength, cast titanium, degassing, low fusion porcelain.