Development and validation of a method for creating incomplete vertical root fracture in extracted teeth.

The present study reported a method for inducing incomplete root fracture in human extracted teeth for the purpose of evaluating the merits of different diagnostic imaging techniques. Thirty-five single-rooted teeth were inspected under magnification and transillumination to exclude previously fractured teeth. Tooth crowns were removed, and the root canals were prepared up to the ProTaper Next X4 (40.06) file. Each root was lined with wax and embedded in a polystyrene resin block. The setup was attached to a universal testing machine for pressing a customized conical wedge (diameter at tip: 0.6 mm; taper: 0.2 mm/mm) into the instrumented canal with a 2 kN load at 5 mm/min. The machine was programmed to stop after a sudden 10% drop in loading force. Each specimen was removed from the resin block and inspected under × 20 magnification and transillumination to identify the fracture characteristics (pattern, surfaces and root-third affected). The gap width of each specimen was measured at different locations along the fracture line. The protocol induced incomplete vertical root fractures in all specimens. Fracture widths were < 100 µm in all specimens (mean gap width: 34.9 µm). The proposed methodology was successful in inducing incomplete vertical root fractures with characteristics that resemble the clinical presentation of these conditions. The method is easy to execute, highly reproducible and helps to minimize bias in laboratory studies that aims to mimic vertical root fractures.

Supplementary methods for filling material removal: A systematic review and meta-analysis of Micro-CT imaging studies.

OBJECTIVE: To evaluate the efficacy of supplementary methods, including Passive Ultrasonic Irrigation (PUI), ultrasonic inserts, XP-Endo Finisher, XP-Endo Finisher R, Easy Clean, sonic activation, and the Er:YAG laser (SWEEPS), in removing residual filling material (RFM) during endodontic retreatment. METHOD: Five electronic databases and gray literature were searched on May 5, 2024. Two independent reviewers selected laboratory studies that assessed the efficacy of supplementary methods for RFM removal using micro-CT imaging. The methodological quality of the studies was evaluated using the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. A meta-analysis was conducted to compare the pooled mean values of initial and final RFM volumes after the use of different supplementary methods. RESULTS: Thirty-two studies were included in the qualitative analysis, and seventeen were included in the meta-analyses. Only seven studies (21.9%) fulfilled all criteria of the methodological quality checklist. No supplementary method has been able to eradicate RFM from root canals. However, the quantitative analysis demonstrated that using PUI, ultrasonic inserts, XP-Endo Finisher, and XP-Endo Finisher R instruments effectively reduced RFM (p<0.05). In contrast, Easy Clean, sonic activation, and Er:YAG laser (SWEEPS) did not demonstrate a significant reduction (p>0.05). CONCLUSION: Supplementary methods were unable to completely remove RFM from the canal walls during endodontic retreatment. However, the use of PUI, ultrasonic inserts, XP-Endo Finisher, and XP-Endo Finisher R instruments has been shown to significantly reduce the amount of RFM. CLINICAL SIGNIFICANCE: Clinicians are encouraged to incorporate supplementary methods for filling material removal during endodontic retreatment to enhance the cleaning of root canal walls.