Resolutions over Dedekind Domains

Question

I want to prove that if $R$ is a Dedekind Domain, then $\operatorname{Ext}_R^n(M,N)=0$, for $n \geq 2$.

Then, I have a question: There are any properties about projective or injective resolutions over Dedekind domains?

For exemple, if exists a projective resolution of lenght one for $M$ it is easy.

Any idea or reference?