Retreatment Pathogenicity and Microbiology​ ​

By Bergenholtz G, Lekholm U, Milthon R, Engstrom B ​

Date: 08/2018
Journal: Journal of Endodontics


To study the effects of over-instrumentation and overfilling on the results of the re-treatments performed in a previous study.​


  • 344 patients (556 roots) underwent endodontic retreatment during 2 years.​
  • the reason for retreatment was either technically incomplete root filling without PA lesion (technical group), or PA lesion present radiographically (osteitis group).​
  • retreatment procedures were done by students under supervision, the procedures were described in details,​
  • New root filling was made by using gutta-percha and resin in chloroform as an adhesive in the canal, according to the multi-cone technique. ​
  • treatment factors including:  overinstrumentation through the apex or if complete mechanical cleansing of the root canal was impossible to perform were recorded.​
  • Within 2 years, the cases were followed up, clinical and radiographical examinations done.​
  • Overfills were registered through radiographs taken before, during, and after re-treatment. Also recorded, was the status of periapical area (whether the original PA lesion had healed completely, was reduced in size, was unchanged, or had increased in size).​


  • In cases  with original PA lesions and no overfilling, 62% of the lesions healed, and 22% reduced in size.​
  •  the rate of healing of PA significantly reduced in cases of overfilling (36%) and in cases where the canals were cleaned  through the apex (over instrumentation): 41%.​

Clinical Significance:

        To create favorable healing conditions when re-treating endodontic cases, a combination of​

         over-instrumentation and overfilling should be avoided.​