Can an expert be found to have waived privileged material?

I am of the view that in putting an expert on the stand, a party does not necessarily waive all privileged materials within their possession. I agree with the court in Piché v. Lecours Lumber Co., supra that privilege is waived in respect of those facts or premises in the expert’s file which have been used to base the expert’s opinion and which came to the expert’s knowledge from documents supplied to that expert. The fundamental question is whether facts, premises, or assumptions were used as the basis or underpinning for the testifying expert’s opinion. If they were, privilege impliedly has been waived.