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

Abstract

Background and Objectives: To compare temporal rates of debris removal from an artificial root canal for three laserassisted irrigation modalities single-pulse super short pulse (SSP), and two dual-pulse X-SWEEPS and AutoSWEEPS, and for two fiber-tip (FT) geometries flat and radial, and to evaluate the dependence of the debris flushing rate on the delay between the SWEEPS laser pulse pair. Study Design/Materials and Methods: Laser-assisted irrigation was performed with a pulsed Er:YAG laser operating in single-pulse SSP and dual-pulse SWEEPS laser modalities. The laser energy was delivered to the water-filled model access cavity through a FT with either a flat or radial ending. The X-SWEEPS modality delivered pairs of laser pulses separated by a fixed adjustable delay, while with the AutoSWEEPS modality the delay was automatically and repeatedly swept between 200 and 600 microseconds. The debris removal rate was determined with the use of a digital camera by measuring the rate at which a simulated debris was being flushed out of the artificial root canal. Results: The simulated debris removal rate of the Au-toSWEEPS modality is almost three times higher compared with that of the SSP modality. Further, the flat FT outperforms the radial FT by a factor of more than five in the case of SSP, and by more than 10 with AutoSWEEPS. The X-SWEEPS flushing rate exhibits strong dependence on the delay between the SWEEPS pulse pair, with the highest removal rate measured to be more than seven times higher in comparison with SSP. Conclusion: Dual-pulse laser irrigation modalities (AutoSWEEPS and X-SWEEPS) exhibit significantly higher simulated debris removal rates in comparison with the standard single-pulse SSP laser-assisted irrigation. As opposed to the previously reported dependence of pressure generation on FT geometry, the flat FT's simulated debris removal rate significantly outperforms the radial FT.

Effect of Optimized Irrigation With Photon‐Induced Photoacoustic Streaming on Smear Layer Removal, Dentin Microhardness, Attachment Morphology, and Survival of the Stem Cells of Apical Papilla

“…In addition, shock waves are also emitted from the collapsing secondary cavitation bubbles that are formed throughout the entire length of the canal during laser‐induced irrigation [36]. SWEEPS irrigation has been shown to result in significantly enhanced flushing action [37,38], and due to the increased pressure generation along with the depth of the root canal, also results in enhanced penetration of irrigants into dentinal tubules [39,40], without increasing the risk of apical extrusion [41]. Further studies are needed to assess the effect of SWEEPS on smear layer removal, dentin microhardness, attachment morphology, and survival of stem cells.…”

Determination of Optimal Separation Times for Dual‐Pulse SWEEPS Laser‐Assisted Irrigation in Different Endodontic Access Cavities

“…The possibility to significantly enhance the effective flushing action of SWEEPS [ 34 ], and to increase the pressure generation along the root canal [ 35 , 36 ], without increasing the risk of apical extrusion needs to be explored to assess the safety of “X‐SWEEPS” modality. Studies in artificial models with apical constriction of ISO40 [ 37 ] and ISO45 [ 35 ] and lateral canal opening of ISO35 [ 35 ] indicate that the new SWEEPS method does not increase the risk of apical extrusion as compared with the single pulse LAI or standard syringe irrigation.…”

“…Furthermore, shock waves are also emitted from the collapsing secondary cavitation bubbles that are formed throughout the entire length of the canal during laser‐induced irrigation [ 24 ]. This dual‐pulse LAI technique, named Shock Wave Enhanced Emission Photodynamic Streaming (SWEEPS), has been shown to result in significantly enhanced flushing action [ 34 ], and due to the increased pressure generation along the depth of the root canal, also results in enhanced penetration of irrigants into dentinal tubules [ 35 , 36 ], without increasing the risk of apical extrusion [ 37 ].…”

“…Under comparable conditions, the AutoSWEEPS modality has been reported to be about 50% more effective than the standard single‐pulse SSP (super short pulse, 50 µs pulse duration) modality in generating pressures within the root canal and significantly better penetration of irrigants into the dentinal tubules [ 35 ]. Also, as measured in laboratory conditions, the simulated debris removal rate of the AutoSWEEPS modality has been shown to be almost three times higher compared with that of the SSP modality [ 34 ]. Similarly, in a recent study, the efficacy of the removal of accumulated hard‐tissue debris from the root canal system for AutoSWEEPS irrigation was compared with the SSP laser‐assisted irrigation as well as with ultrasonically activated irrigation (UAI) using micro‐computed tomography [ 39 ].…”

“…The aim of this study was to investigate whether it is possible to pre‐determine and set the optimal SWEEPS pulse pair separation time T opt based on the dimensions of the mesiodistal (lateral) side of the endodontic access cavity, to improve the LAI irrigation efficacy even further. Namely, the simulated debris removal rate of the X‐SWEEPS modality has been observed to be higher by another factor of about three in comparison to that of the AutoSWEEPS modality in case of optimal pulse separation time selection [ 34 ]. In this order, bubble oscillation times were measured in differently sized access cavities, progressively widened in three different steps on extracted teeth for different fiber‐tip geometries, laser pulse energies and depth of fiber‐tip insertion.…”