40-Years Outcome of Old-School Non-Surgical Endodontic Treatment: Practice-based Retrospective Evaluation

(1) Background: Non-surgical endodontic treatment has been repeatedly shown to be clinically successful, however, clinical data are scarce. This practice-based retrospective clinical study aimed to investigate endodontic outcome over 40 years and to identify relevant factors from clinical protocols. (2) Methods: Two experienced dental practitioners in two different private dental practices treated 174 patients with 243 teeth from 1969 to 1993. After obturation, either a new restoration (amalgam, resin composite, glass-ionomer cement), or re-cementation of pre-existing prosthetic restorations or its renewal followed. Metal posts (operator A) or screws (operator B) were inserted when indicated. The primary outcome (tooth survival) was achieved when the endodontically treated tooth was in situ, painless and in full function. Secondary outcome was to investigate the impact of potential prognostic factors on survival rates. (3) Results: Overall mean 40-years survival was 56.1% of all treated teeth after 40 years of clinical service resulting in an annual failure rate of 1.1%. Most investigated clinical factors (Jaw, tooth position, number of intracanal dressings, post/screw placement, sex) had no significant influence on survival. Among postendodontic restorations, resin composite was advantageous. (4) Conclusions: Even with materials and techniques from the 1970’s and 1980’s, successful root canal treatment was achievable. Except postendodontic restorations, most of the evaluated factors had no significant influence on clinical long-term survival of root-canal treated teeth.