Base metals are known to have higher free-surface energy and are more reactive than noble and high noble alloys
forming a thicker oxide layer.
 Barghi et al measured the fracture strength of repeatedly fired porcelain veneered to high noble and base metal alloy crowns and reported that multiple firings decreased the fracture strength in high noble alloys
but did not significantly affect base metal alloys.
The strength and rigidity of titanium are comparable to those of other noble or high noble alloys
commonly used in dentistry [27, 28].