Re: zirconium or metal bridge?
Zirconium is a lot like porcelain. A bit weaker than titanium or other metals, and most dentists tend to talk you out of using zirconium.
However, metal is metal, and no metal should be in anyone's body. Especially in your mouth.
As to implants/artificial roots, usually the metal is not even titanium, but an alloy of titanium, chromium and aluminum, and the latter causes Alzheimer's Disease.
Metal bridges are more elaborate/complex/obvious and depend on the dental lab your dentist uses. Too many times the lab uses nickel. However, if you want to preserve your health, no metal/nickel should be used, even if it's embedded in some kind of plastic or other metal.
IMO, it's not a good enough reason to use something just because it's not 100% metal.
Is zirconium 3 times more expensive than metal? Look up the facts, but be reasonable. ANYTHING can be considered very expensive if you compare it to something INexpensive like (cheap and unhealthy) nickel. Would you rather save money and display a set of metal teeth?
Why do you want/need any bridges in the first place? The bridge is a lousy idea. Why would any person create an artificial 3rd tooth at the expense of two or more good ones?