Assessment of healing after primer endodontic treatment and retreatment using fractal analysis and PAI score over a 24-month follow-up

The aim of this study was to compare the healing after 24 months between initial endodontic treatment and retreatment using fractal analysis and the periapical index (PAI) scores. Eighty-three mandibular teeth with 5 mm lesions from 76 patients were selected, and then the teeth were divided into two groups: the primary endodontic treatment group and the retreatment group. Panoramic X-rays evaluated before and after 2 years of treatment were determined in both treatment groups. Differences between groups were evaluated by fractal analysis. Post-treatment fractal dimensions were not statistically significant in either group compared to pre-treatment values ( p > 0.05). In the primary endodontic treatment group, the mean pre-treatment fractal dimension value was 1.48 ± 0.11 (mean ± SD), while it was determined as 1.52 ± 0.12(mean ± SD) at 24 months of follow-up. In the retreatment group, the mean pre-treatment fractal dimension value was 1.45 ± 0.16 (mean ± SD), while it was determined as 1.50 ± 0.15(mean ± SD) at 24 months of follow-up. There was no statistically significant difference between the groups in terms of fractal dimension differences. Statistically significant decreases were observed in PAI values within the group ( p < 0.001), and no significant difference was observed between the groups in terms of time-dependent decreases ( p > 0.05). In the primary endodontic treatment group, the PAI score was 4.83 ± 0.38 (mean ± SD) before treatment, while it was determined as 1.71 ± 1.33(mean ± SD) at 24 months of follow-up. In the retreatment group, the pre-treatment significance level was 4.76 ± 0.43(mean ± SD), while at 24 months of follow-up it was determined to be 1.80 ± 1.21(mean ± SD). Fractal analysis may provide complementary quantitative information regarding periapical bone changes; however, FD measurements obtained from panoramic radiographs should be interpreted cautiously because of the inherent limitations of this imaging modality. Integrating fractal analysis with traditional scoring systems allows for a comprehensive assessment of long-term bone formation in both primary endodontic treatment and retreatment. Consequently, both primary endodontic treatment and retreatment showed similar patterns in periapical bone healing over 24 months, and no significant difference was found between the two groups in fractal dimension values or PAI scores. The absence of statistically significant FD changes should not be interpreted as definitive evidence of absent trabecular remodeling.