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Retrospective fractal analyses of one-year follow-up data obtained after single-visit nonsurgical endodontic retreatment on periapical radiographs



The aim of retrospective study was to evaluate the changes to the periapical bone sites after non-surgical endodontic retreatment by using fractal analysis on periapical radiographs.

Materials and methods

Thirty patients whose teeth had periapical lesions and underwent primary endodontic treatment were selected for nonsurgical single-visit endodontic retreatment. Two radiographs were taken, the first immediately after retreatment and the second at the 1-year follow-up. An identical region of interest close to the infected root apex was selected from each radiograph. FD was measured using the box-counting method. Periapical status was evaluated using the periapical index (PAI). Treatment outcomes were categorized into healed (PAI < 3), or not healed (PAI ≥ 3) based on radiographic criteria.


The mean FD value significantly increased at the 1-year follow-up compared to baseline. No significant sex biases were apparent. According to the PAI, retreatment after 1 year resulted in a 63.3% healed.


The extent of periapical trabecular bone evident radiographically increased, as revealed by FD data, 1 year after endodontic retreatment.

Clinical relevance

The use of fractal analysis as a quantitative method to evaluate changes in periapical trabecular bone (such as healing and inflammation) after endodontic retreatment can be an important marker in determining the prognosis of endodontic retreatment.

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The authors would like to thank Hande Şenol for her assistance as statistical analyzer.

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Corresponding author

Correspondence to Samet Tosun.

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Ethics approval

The study was approved by the Pamukkale University Ethics Committee (approval number E-60116787–020–4352).

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The need for informed patient consent was waived because we used only anonymized retrospective data.

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The authors declare no competing interests.

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Tosun, S., Karataslioglu, E., Tulgar, M.M. et al. Retrospective fractal analyses of one-year follow-up data obtained after single-visit nonsurgical endodontic retreatment on periapical radiographs. Clin Oral Invest 25, 6465–6472 (2021).

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  • Fractal
  • Diagnostic imaging
  • Dental radiograph
  • Retreatment
  • Retrospective studies