Influence of Rubber Dam Isolation During Permanent Coronal Restoration on the Survivability and Success of Endodontically Treated Teeth

Objectives: Root canal re-infections lead to endodontic treatment failure. Rubber dam isolation (RDI) is the standard of care during endodontic therapy, but is not consistently used during permanent coronal restoration placement on endodontically treated teeth. We hypothesize that RDI during placement of permanent coronal restorations on endodontically treated teeth will enhance tooth survivability. We also hypothesize that these teeth are less likely to require endodontic retreatment, when judged by the lack of periapical bone lesion formation and absence of symptoms.
Methods: Three thousand two hundred electronic charts and accompanying radiographs of patients that underwent endodontic therapy were obtained from the University of Pittsburgh School of Dental Medicine after IRB approval. Endodontically treated teeth were sorted into two groups: those with permanent restoration placed under RDI, or those without. Time to placement of permanent coronal restoration was recorded as well. Teeth with follow-up radiographs and clinical testing of at least 12 months after endodontic therapy were included to determine endodontic treatment success.
Results: Of 223 teeth, 40.8% had permanent restoration placed under RDI. 91.2% (n=91) of teeth with permanent restoration placed under RDI and 65.9% (n=132) of teeth with placement without RDI were present in the mouth a year after treatment (p=0.000013). There was no significant difference between tooth survivability and time interval to permanent restoration. For cases with follow up radiographs and clinical testing of at least one-year after endodontic therapy and use of a RDI during coronal restoration within 60 days, 100% of cases did not require retreatment as compared to 64.3% (n=22) when restored after 60 days. For teeth restored without RDI, success rate was lower when restored within 60 days (61.5%, n=18, p=0.05).
Conclusions: Rubber dam isolation is important not just during endodontic treatment, but also during placement of a permanent restoration. Moreover, timely placement of the permanent coronal restoration significantly enhances the prognosis of endodontically treated teeth.