Antibacterial Effects of the iVac Endodontic Irrigation System Within Dentinal Tubules: An In Vitro Confocal Microscopy Study

Background: This study compared the antibacterial efficacy of iVac and conventional syringe-and-needle irrigation, used with an identical standardized antimicrobial irrigant regimen, by evaluating bacterial viability and the depth of membrane-compromised bacterial cells within dentinal tubules. Methods: Forty-two extracted human teeth were instrumented, sterilized, and inoculated with Enterococcus faecalis ATCC 29212. Specimens were randomly assigned to iVac irrigation (n = 20) or conventional 30G syringe-and-needle irrigation (n = 20). Both protocols employed the same irrigation sequence consisting of 5% NaOCl, 10% EDTA, 5% NaOCl, and saline. After treatment, the teeth were sectioned, stained with the BacLight viability kit, and analyzed by confocal laser scanning microscopy (CLSM) to determine the mean proportion of red staining (MPRS) and mean penetration depth (MPD) defined as the depth within dentinal tubules at which PI-associated red fluorescence corresponding to membrane-compromised bacterial cells was detected in the coronal, middle, and apical thirds. Statistical significance was set at p < 0.05. Results: No significant difference in mean proportion of red staining (MPRS) was found between the two groups (p = 0.24). In contrast, mean penetration depth (MPD) was significantly greater with iVac overall (p = 0.021), particularly in the coronal and middle thirds (p = 0.015 and p = 0.032, respectively). No significant difference was observed in the apical third (p = 0.12). Conclusions: Under the present experimental conditions, the iVac and conventional syringe-and-needle irrigation protocols resulted in comparable overall bacterial viability outcomes. However, the iVac protocol was associated with a significantly greater depth of membrane-compromised bacterial cells within dentinal tubules, particularly in the coronal and middle thirds.