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Impact of electrode distance, axial position, and energization time on cauterization of root canal isthmuses using
Ahmed Saud Alkuwaykibi1, Tsutomu Sugaya2, Mohammed Katib Alruwaili3
1Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-Ku, Sapporo, Hokkaido, 060-8586, Japan. Ahmed.Saud.Alrawily@jodent.org.
Objectives:
This in vitro proof-of-concept study evaluated how the isthmus gap width, distance between electrodes, and duration of high-frequency electrical current application affect surface morphological changes of simulated isthmus inner surfaces.
Materials And Methods:
Simulated isthmus models were prepared using bovine dentin blocks immersed in Plank-Rychlo solution to create organic layers. Isthmus gap widths of 0.1, 0.2, and 0.3 mm were created. Two root canals were prepared at distances of 2 mm or 5 mm, creating six groups (n = 10 each). Root canals were filled with NaOCl, and #35 K-files served as electrodes. A high-frequency current (225 V, 520 kHz) was applied for 5 or 10 s. The demineralized surface morphology (decalcified surface) prior to HFC application served as the baseline reference for evaluating cauterization outcomes. Isthmus surfaces were analyzed using scanning electron microscopy and energy dispersive X-ray spectroscopy.
Results:
High-frequency current application produced surface morphological changes consistent with cauterization, including exposure of dentinal tubules. Fisher's exact test showed significant differences in cauterization rates, since Group 1 showed less organic residue than Groups 4 and 5 (p < 0.05). In Groups 3 and 4, 10-s application significantly decreased organic material compared to 5-s application (p < 0.001). Ordinal logistic regression analysis confirmed that electrode distance (OR = 0.854, p < 0.0001), axial position (OR = 0.444, p < 0.0001), and energization time (OR = 3.276, p < 0.0001) were significant predictors, whereas gap width was not (p = 0.542). Coronal regions showed significantly higher cauterization rates than apical regions (91.6% [466/509] vs 68.2% [347/509]).
Conclusions:
Within the limitations of this in vitro proof-of-concept study, electrode distance, axial position, and energization time significantly influenced surface morphological outcomes. Extending energization time from 5 to 10 s increased the odds of achieving higher-grade surface morphological changes by 3.3-fold. Gap width did not significantly affect the outcome.
Clinical Relevance:
Electrode distance, axial position, and energization time are critical parameters for high-frequency cauterization of simulated root canal isthmuses. These proof-of-concept findings may inform future investigations into the clinical application of this technique for areas inaccessible to conventional instrumentation.
