Affiliations: Dental Material Division, Department of Restorative Dentistry, Indiana University School of Dentistry, 1121 West Michigan Street, Indianapolis, IN 46202‐5186, USA | University of the East, College of Dentistry, Department of Prosthodontics, Claro M. Recto, Manila Metro‐Manila, Philippines
Note: [] Corresponding author: Yoshiki Oshida, PhD, Professor, Dental Materials, Department of Restorative Dentistry, Indiana University School of Dentistry, 1121 Wets Michigan Street, Indianapolis, IN 46202‐5186, USA. Tel.: +1 317 274 3725; Fax: +1 317 274 2415; E‐mail: yoshida@iupui.edu.
Abstract: The titanium–porcelain system can be considered as a double‐layered structure, comprising of at least titanium substrate and porcelain body including bonding agent. Stress distribution pattern of such a double‐layered structure is not necessarily same as that of a single beam under the 3‐point bending testing mode. Previously tested porcelain‐fired commercially pure titanium samples (n=285) were re‐evaluated. All obtained data on bond strengths and bond toughness (energy‐to‐break) were re‐grouped in terms of c/t ratio, where c is the distance from the maximum compressive side of the beam to the calculated neutral axis and t is the thickness of titanium substrate plate thickness. It was found that (1) when the double‐layered structure falls in the c<t situation, both bond strength and bond toughness are in a lower zone, which is slightly lower than the cohesive tensile strength of the porcelain, (2) when the c>t situation (with relatively thick porcelain application) is established, both bond strength and toughness are in higher zone than the porcelain itself, and (3) there is a transition zone between the above.
