The only way I know how to determine if a tooth has enough remaining structural integrity is to mesure the width and height clinically and/or on x-ray with imaging software tools. But of course, that evaluation has to be done prior to endodontic treatment, as the proposed treatment plan and consent depend on that information, ie knowing if the tooth is restorable post-endo beforehand and if so, what type of restoration is needed.

I understand that post-endo evaluation is necessary to confirm treatment plan, but pre-endo evaluation is a must and not doing so would be malpractice.

For an ex vivo study, the teeth can be scanned pre- and post- endo treatment using 3D Xray imaging like CBCT or micro-CT. In case of an in vivo study, CBCT imaging is the best pption although there would be concerns regarding Xray exposure.