Does dental crown made from zirconiun has materials that cause cancer?

[nefeli_ck]

My mum had breast cancer and she was under chemo and radiation therapy.Therapy was finished on April 2010, and now started dental therapy. She will remove 2 crowns and she is thinking which crowns is best for her.
I was searching for crowns and read for crowns made from zirconia and i wanted to know if zirconium crowns has materials in it (eg titanium) that can cause cancer and if they are high risk for cancer.

Which crowns are best for use, especially for persons that have pass chemo in the past, and how long time must be passed from chemo and radiation to start dental therapy(eg, change of fillings, corwns, etc).

Thank you and waiting for your early reply because she has to start immediately her therapy.

[Dr Pav Khaira]

There is no evidence to suggest that any crown or bridge material has the ability to cause cancer. Without a full history, diagnosis and medical prognosis and examination it's difficult to give any advise

I hope this helps