Not every tooth that has been endodontically treated requires a crown to insure it has great longevity and doesn’t crack or fracture.
Very clearly the literature supports that molar teeth in the posterior absolutely must have four cusp coverage—a four-cusp onlay or a full coverage crown. We are trying to use the phenomenon of containment with strong ceramic or metal material around the entire circumference of the tooth. We are holding the buccal and lingual together and replacing the top of the root chamber, so the tooth doesn’t fracture.
Bicuspids that have been endodontically treated do not need two-cusp coverage if there have been no previous restorations and the endo access is very conservative. In the case of a premolar that has never had an MO, a DO, or an MOD, and has a tiny access hole, you can do a composite buildup or chamber retaining composite restoration. If the patient has high functional risk, a reasonable decision would be to restore the tooth with an onlay or crown
There is no scientific support for doing a crown on an anterior tooth just because it has had endodontic therapy. We do a crown on an anterior tooth that has had endo when it is already structurally compromised, for example with previous mesial lingual and distal lingual composite fillings, missing tooth structure, and significant structural compromise between the endo access and other restorations.