IntroductionThe aim of this prospective randomized clinical trial was to evaluate the effect of a time lapse between endodontic treatment and nonsurgical periodontal treatment on periodontal healing of concurrent endodontic-periodontal lesions without communication. MethodsThirty-one patients were randomly divided into 2 groups: group 1: endodontic treatment and scaling and root planning (SRP) were performed simultaneously and group 2: SRP was performed 3 months after endodontic treatment. Both groups were followed for 3 and 6 months after SRP. Primary outcome variables were the probing depth, clinical attachment level, and periapical index score. ResultsBoth the groups showed a significant improvement in all the clinical parameters evaluated after the completion of endodontic and periodontal treatment (P < .05). No statistically significant difference in improvement was observed between the 2 groups at 3 and 6 months after SRP (P > .05). Periodontal healing responses were comparable in the 2 groups, with no apparent detriment resulting from simultaneous treatment. Improvements in periodontal parameters that were achieved in 6 months in group 2 were achieved only in 3 months in group 1 (P > .05). ConclusionsNonsurgical periodontal treatment may be performed simultaneously with endodontic treatment in the management of concurrent endodontic-periodontal lesions without communication, and an observation period after endodontic treatment may not be required.