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Comparative Evaluation of Advanced Irrigant Activation Protocols on Hydrogel Removal From Standardized Artificial
Alfonso Acerra1, Dina Abdellatif2,3,4, Francesco Giordano1
1Department of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy.
Objective:
To compare irrigant activation protocols for hydrogel removal from standardized artificial lateral canals.
Materials And Methods:
One hundred and seventy-six 3D-printed resin blocks reproducing a standardized root canal with two lateral canals were used. The lateral canals were filled with gelatin-hyaluronan hydrogel as an organic-debris surrogate. Blocks were randomized to 16 groups (A1-A8, B1-B8; n = 11/group). Group A protocols used 3% sodium hypochlorite (NaOCl), whereas Group B protocols used 3% NaOCl with Dual Rinse HEDP. The primary outcome was net specimen mass loss (W2-W3), determined gravimetrically. Optical microscopy provided descriptive support. Non-parametric analyses were applied to the gravimetric outcome (α = 0.05).
Results:
Saline controls and conventional syringe-irrigation groups showed no detectable net mass loss at the balance readability of 0.1 mg. Net mass loss increased from sonic and ultrasonic activation to protocols combining internal heating with activation. Groups A7 and B7 produced the greatest median net mass loss (0.60 mg). Descriptive microscopy indicated greater hydrogel removal from the smaller apical lateral canal in Groups A6-A8 and B6-B8 than in Groups A3-A5 and B3-B5, with the greatest removal in A7 and B7. No significant gravimetric differences were detected between corresponding Group A and Group B protocols (p > 0.05).
Conclusions:
Within the limitations of this thermosensitive hydrogel model, protocols combining internal heating with manual dynamic, ultrasonic or sonic activation were associated with greater net mass loss and microscopy-based hydrogel removal than conventional irrigation or single-mode activation. Although consistent with the temperature-dependent increase in NaOCl tissue-dissolving activity, chemical dissolution could not be distinguished from thermally induced hydrogel softening and mechanical displacement. No protocol completely removed hydrogel from the smaller apical lateral canal, and the findings should not be extrapolated directly to clinical root canal systems.