Comparison of the Antibacterial Effect and Smear Layer Removal Using Photon-Initiated Photoacoustic Streaming Aided Irrigation Versus a Conventional Irrigation in Single-Rooted Canals: AnIn VitroStudy

Abstract

Objective: The Er:YAG laser with photon-induced photoacoustic streaming (PIPS) technique was reported to be effective in root canal disinfection. This study attempted to further investigate the antibacterial efficacy and smear layer removal ability of PIPS in comparison with conventional syringe irrigation in vitro. Methods: For antibacterial analysis, 48 single-rooted human teeth were prepared and inoculated with Enterococcus faecalis, and then divided into six groups of eight roots each. The colony-forming units (CFUs) per milliliter were determined after infection as the baseline. Then, the teeth were subjected to either PIPS plus 3% sodium hypochlorite (PIPS + NaOCl) or conventional syringe irrigation with 0.9% saline, 3% NaOCl, 17% ethylenediaminetetraacetic acid (EDTA), 0.2% chlorhexidine gluconate (CHX), or 3% NaOCl alternating with 17% EDTA. The reduction of CFUs in the individual group was determined. Additionally, scanning electron microscopy (SEM) examination of the canal walls for E. faecalis colonization was performed. For comparing the smear removal efficacy, another 48 single-rooted teeth, assigned to different groups as mentioned, were irrigated after mechanical instrumentation. The presence of a smear layer at different levels of the root canal was scored by SEM examination. Results: No significant differences were found in CFU reduction. No bacteria could be observed by SEM in the NaOCl, NaOCl + EDTA, and PIPS + NaOCl groups. The scores of smear layer of the NaOCl + EDTA and PIPS + NaOCl groups were significantly lower than those of the other groups in the coronal and middle third of the root canal. None of the methods can effectively remove smear layer in the apical third. Conclusions: PIPS system supplied with NaOCl and conventional syringe irrigation with NaOCl + EDTA are comparable in their ability to remove E. faecalis and smear layer in single-rooted canals.

Efficacy of Needle, Ultrasonic, and Endoactivator Irrigation and Photon-Induced Photoacoustic Streaming in Removing Calcium Hydroxide from the Main Canal and Isthmus: AnIn VitroMicro-Computed Tomography and Scanning Electron Microscopy Study

“…Alternatively, the energy of PIPS may not have been sufficient to activate irrigant flow in the apical third. 39 Similarly, acoustic microstreaming and/or cavitation significantly decreases or disappears when the activated tip leaves the irrigant and enters the apical vapor lock. 40 Therefore, more effective methods of completely cleaning the apical portion need to be developed.…”

Laser-based Disinfection of the Root Canal System: An Update

“…Al Shahrani et al 40 also concluded that PIPS/6% NaOCl combination may be more effective than combination of PIPS and water. In another in vitro study, Zhu et al 38 showed no significant difference in reduction of bacteria in NaOCl+et hylenediaminetetraacetic acid, NaOCl, and PIPS+NaOCl samples. Olivi et al 45 also concluded that PIPS can enhance the effect of irrigants commonly used during endodontic treatment.…”

“…The mechanism is considered as inducing a strong photoacoustic shock wave that can stream irrigation solutions three-dimensionally throughout the canal. 37,38 Unlike some other conventional applications of the laser, placing the unique-tapered tip inside the canal itself is not mandatory but rather in chamber only. This has been indicated to effectively remove tissues and disinfect the tubules.…”

Effect of different irrigant activation protocols on push-out bond strength

“…A recent study [13] showed that the use of an Er:YAG laser with minimally ablative laser settings through a photoacoustic technique called the photon-induced photoacoustic streaming (PIPS) technique achieved effective debris and smear layer removal. It was suggested that this method had a three-dimensional positive effect on smear layer removal, limiting the undesirable thermal and ablative effects of the laser device [22,23].…”

“…To date, the smear layer removal efficacy of PUI [10,11], ANP [1,10], diode [24], Nd:YAG [15], and Er:YAG lasers [12], as well as the PIPS technique [23], has been investigated. Thus, these techniques can be considered as possible treatment approaches to optimize the smear layer removal efficacy, but little is known about the bond strength of fiber posts to dentine after the smear layer is removed by these techniques.…”