Micro‐CT study on the removal of accumulated hard‐tissue debris from the root canal system of mandibular molars when using a novel laser‐activated irrigation approach

Abstract

Aim To compare the efficacy of ultrasonically activated irrigation (UAI), photon‐induced photoacoustic streaming (PIPS) and shock wave enhanced emission photoacoustic streaming (SWEEPS) activation for the removal of accumulated hard‐tissue debris (AHTD) from the root canal system of mandibular molars when assessed using microcomputed tomography (micro‐CT). Methodology A total of 30 mandibular first and second molars with joining mesial root canals containing an isthmus and a single distal canal were subjected to three micro‐CT scans (before and after canal instrumentation and after final irrigation) at a resolution of 15 μm. Mesial canals were prepared up to a ProTaper F3 rotary file, and distal canals were prepared up to a ProTaper F4 rotary file. Teeth were randomly assigned to three groups according to the irrigant activation method (n = 10): the UAI group, the PIPS group and the SWEEPS group. The final irrigation procedures were performed using a total of 15.5 mL of 1% NaOCl for each tooth with an activation time of 3 × 30 s. After three‐dimensional model reconstruction and volumetric measurement of root canals, the percentage reduction (%Rd) of AHTD was calculated. The %Rd of AHTD was analysed statistically using one‐way analysis of variance and nonparametric tests at a significance level of 5%. Results There were no significant differences between the three groups in terms of canal volume before or after instrumentation, or the volume of debris after canal preparation (P > 0.05). In the mesial canals, irrigation with SWEEPS reduced the overall debris by 84.31%, which was significantly more than the reduction associated with PIPS and UAI (58.79% and 50.27%, respectively). In the distal canals, the %Rd of AHTD was significantly different between PIPS and SWEEPS and between UAI and SWEEPS (P < 0.05), but was not significantly different between PIPS and UAI groups (P > 0.05). The SWEEPS was associated with a greater %Rd of AHTD than the PIPS and UAI groups. Conclusions SWEEPS was associated with significantly less debris compared than PIPS and UAI, especially in isthmus‐containing mesial roots. None of the activation techniques completely removed debris from root canal systems.

Electrochemical dissolution of nickel‐titanium instrument fragments in root canals of extracted human maxillary molars using a small reservoir of electrolyte

“…This result cannot be compared to the previous studies, where bi-dimensional methods of analysis, as radiographic analysis, and scanning electron microscopy analysis were used (Ormiga et al 2015, Kowalczuck et al 2019. Micro-CT analysis has been used extensively in endodontic studies because it is a non-invasive method that enables comparison between three-dimensional parameters before and after the endodontic procedures (Nielsen et al 1995, De-Deus et al 2014, Belladonna et al 2018, Keles et al 2020, Yang et al 2020. In the present study, the fragment volume was measured before and after the dissolution process, where the control group was composed of teeth containing the fragments before the dissolution.…”

“…2020, Yang et al . 2020). In the present study, the fragment volume was measured before and after the dissolution process, where the control group was composed of teeth containing the fragments before the dissolution.…”

Measurement of Simulated Debris Removal Rates in an Artificial Root Canal to Optimize Laser‐Activated Irrigation Parameters

“…This in vitro study compared the efficacy of three different laser activation techniques on the removal of simulated debris from an artificial root canal using camera imaging of the depth of the canal's cleaning. The removal of hard-tissue debris has been assessed using a number of different methods, including camera imaging [9,10,33], scanning electron microscopy [34], histology [35], and micro-computed tomography [32]. In this study, we used a relatively simple artificial root canal model and a different camera imaging method than typically used, in order to be able to evaluate not only the amount of the remaining simulated debris but also the rate of removal.…”

“…Under comparable conditions, the AutoSWEEPS modality has been reported to be about 50% more effective than standard SSP in generating pressures within the root canal, signifying about 50% better penetration of irrigants into dentinal tubules [. Also, in a recent study [32], the efficacy of the removal of accumulated hard‐tissue debris from the root canal system for the AutoSWEEPS irrigation was compared with the SSP laser‐assisted irrigation as well as with ultrasonically activated irrigation (UAI) using microcomputed tomography. The AutoSWEEPS modality resulted in significantly improved debris removal in each portion of the root canals compared with SSP and UAI.…”

Response to the letter to the editor‐ Is EDTA the protagonist for the enhancement of accumulated hard tissue debris removal from root canals?

“…Although most of the study designs do not exclude EDTA from their irrigation protocols, which can make it impossible to prove the action of sodium hypochlorite in the removal of accumulated hard tissue debris, a recent study (Yang et al . 2020) evaluated the efficacy of several irrigation protocols on the removal of accumulated hard tissue debris from the root canal system of mandibular molars using only sodium hypochlorite as an irrigating agent. The results of this study clearly pointed to a reduction in accumulated hard tissue debris, in different proportions in the tested groups, but using solely sodium hypochlorite without any chelating agent.…”