Fractal analysis and periapical index evaluation of multivisit nonsurgical endodontic retreatment: A retrospective study

Abstract

This retrospective study compared changes in periapical trabecular patterns using fractal analysis and the periapical index (PAI) on the periapical radiographs of patients who underwent multivisit nonsurgical endodontic retreatment of persistent periapical disease. In total, 50 participants were included in the study. For each patient, baseline periapical radiographs were acquired just before retreatment and postoperative radiographs were acquired 1 year later. The region of interest, located in the abnormal tissue around the root apex, was selected from each of the paired radiographs and the fractal dimension (FD) was calculated. Periapical status was classified using the PAI as "healed" (PAI <3) or "unhealed" (PAI ≥3). According to the PAI scores, retreatment after 1 year had a healing rate of 70%. In healed cases, the FD values increased significantly (P < .001), whereas FD decreased significantly in unhealed cases (P = .021). Change in FD was significantly different between healed and unhealed cases (P < .001). However, change in FD did not have a significant correlation with PAI in either healed or unhealed cases (P > .05). There was no significant effect of sex on the change in FD values in either healed or unhealed cases (P ≥ .690). The significant differences in FD suggest that this parameter may be useful in detecting increased trabeculation and estimating retreatment prognosis.