Why are dentists saying that Zirconia dental implants are better than Titanium implants? Is this true?

There is no question that titanium implants have the best long term data to support their use.  The data on zirconia implants is much more limited.  Zirconia is a metal but the crystalline form of the metal so it doesn't act like a metal in the mouth.  I am actually more concerned does the material match the patients immune system.  The Clifford test can tell whether your immune system is sensitive to a specific brand of implants.Some of my referring doctors do not want their patients to have any metallic restorations or implants in their bodies and zirconia implants allow these patients an alternative to titanium.Many years ago single crystal sapphire implants were also used but I don't hear much about them today.

Zirconium is a transitional metal, so "pick your metal".  It corrodes as well, just differently. I am not aware of any reports of corrosion ever causing problems with titanium implants (implant problems are for other reasons).  Zirc also has a higher fracture rate (not "just as strong" as you state), does not integrate with the bone as well, titanium IS biocompatible (the reason it integrates with bone is BECAUSE of its biocompatiblity).  I have seen no zirconium data stating it fights infection.  Galvanic currents require a dissimilar metal to get in close contact, and an implant never has that happen (so there is no risk for EITHER material).  Thermal conductivity is a non issue since the implant never leaves the bone and there are no nerves in bone to report any changes.Titanium will not go away as a material of choice in implant dentistry in your or my lifetime.

Another great question.  Titanium has been used with great success as an implant to support a tooth replacement.  There are problems with titanium as you describe.  Zirconia does overcome these issue and provides strength and amazing gum health around them, which sometimes with titanium is not optimal.  Our practice uses over 80% CeraRoot Dental Implants in tooth replacement procedures and have had amazing success.  Titanium is still used in certain situations, but our ideal tooth replacement is CeraRoot.Hope this helps.