Photon-initiated photoacoustic streaming (PIPS) with an Er: YAG laser has been introduced in root canal treatment to improve irrigation and facilitate the removal of bacteria in the root canal system. This study aimed to compare the antibacterial effectiveness of two different root canal irrigation techniques, conventional needle irrigation (CNI) and PIPS, using 1% sodium hypochlorite (NaOCl), in the treatment of teeth with apical periodontitis. Sixty patients with a total of sixty teeth affected by apical periodontitis were included in this study. The teeth underwent root canal therapy, and after mechanical instrumentation, they were randomly assigned to two groups (n = 30) based on the final irrigation protocol: CNI or PIPS with 1% NaOCl. Bacterial suspensions in the root canals were evaluated using Adenosine 5\'-triphosphate (ATP) assay kit after mechanical instrumentation and after final irrigation. Then, a follow-up was conducted after 7 days. The results revealed that final irrigation significantly reduced ATP values in both the CNI and PIPS groups (P < 0.001). The ATP values after final irrigation was greater in the CNI group compared to the PIPS group (P < 0.001). After a 7-day follow-up, percussion tenderness and fistula were significantly resolved in both groups (P < 0.05). A multivariate linear regression model was used to identify the factors that influence post irrigation ATP values. The analysis demonstrated that pre-operative percussion tenderness (P = 0.006), the presence of a fistula (P < 0.001) and the method used in the final irrigation (P < 0.001) had a significant impact on the ATP value after final irrigation. These results indicate that employing PIPS with 1% NaOCl as the final irrigation protocol exhibited superior antibacterial effectiveness and has the potential to enhance clinical outcomes in the treatment of teeth afflicted with apical periodontitis.

UNASSIGNED: Photon-induced photoacoustic streaming (PIPS) with pineapple peel extract (PPE) and ethylenediaminetetraacetic acid (EDTA) as a final endodontic irrigant on the push-out bond strength (PBS) of root filling material to conventional irrigation NaOCl with EDTA.
UNASSIGNED: An in vitro study at Dar Al Uloom University was conducted over three months. Root canal preparation was performed. Based on final irrigation, all the specimens were divided randomly into four groups (n=10) Group 1: 2.25% NaOCl+ 17% EDTA (control), Group-2: 2.25% NaOCl+PIPS + 6.25% PPE, Group-3: 2.25% NaOCl+PIPS + 17% EDTA, Group-4: 2.25% NaOCl + 6.25% PPE. Canals were obturated and sealed with AH Plus sealer. Root sectioning was performed at 1mm thickness and PBS testing was performed using the universal testing machine. The debonded samples were analyzed for failure mode. ANOVA compared the means and standard deviations (SD) of all investigated group. Assessment of multiple comparisons was performed using Tukey\'s post hoc test.
UNASSIGNED: The maximum PBS was demonstrated by the coronal section of Group-2 (2.25%NaOCl +PIPS+6.25%PPE) specimens (8.21±0.81MPa). The apical section of Group-1 (2.25% NaOCl+17% EDTA) specimens demonstrated minimum bond strength (2.80±0.18 MPa). The intergroup comparison revealed that Group-3 (2.25% NaOCl +PIPS +17% EDTA) and Group-2 demonstrated comparable outcomes (p>0.05). Group-4 (2.25% NaOCl +6.25% PPE) specimens established significantly lower values than Group-3 and Group-4 (p<0.05).
UNASSIGNED: Photon-induced photoacoustic streaming with pineapple peel extract and EDTA demonstrated better bond strength of root canal sealer and have the potential to be used as the final irrigant.

OBJECTIVE: The aim of the present study was to visualize and compare the cavitation effect and fluid dynamics induced by photon-induced photoacoustic streaming (PIPS) using sodium hypochlorite (NaOCl) with different concentrations as irrigant.
METHODS: Forty artificial root canals were prepared using MTWO Niti file up to size #25/.06. The canals were randomly divided into four groups (n = 10/group). High-speed camera was used to visualize and compare the cavitation effect induced by PIPS in the artificial root canals containing saline or NaOCl. Fluid velocity and Reynolds number of saline, 1%-, 2.5%- and 5.25% NaOCl irrigants induced by PIPS in the apical region were calculated using TEMA 2D software while the fluid motions were recorded.
RESULTS: Visualization profile revealed that NaOCl presented a stronger cavitation effect and fluid dynamics than saline during PIPS activation. In the apical region, 1% NaOCl group presented the highest average velocity of 3.868 m/s, followed by 2.5% NaOCl group (3.685 m/s), 5.25% NaOCl group (2.353 m/s) and saline group (1.268 m/s), corresponding to Reynolds number of 1653.173, 1572.196, 995.503 and 477.692. Statistically higher fluid velocity was calculated in 1% and 2.5% NaOCl groups compared to saline group, respectively (p < 0.05).
CONCLUSIONS: The application of NaOCl and its concentration significantly influence the cavitation effect and fluid dynamics during PIPS activation. 1% and 2.5% NaOCl groups presented a more violent fluid motion in the apical region when activated by PIPS.

In recent years, the concept of minimally invasive endodontics has been proposed, which could be described as preventing or treating diseases by preserving more dental tissue and creating minimal damage. In the process of root canal preparation, it was recommended to use instruments with a smaller taper to preserve more tooth tissue and improve the preservation rate of the affected teeth. Photon-induced photoacoustic streaming (PIPS) was a new type of laser-activated irrigation technology, which was now widely used in endodontic treatment. The purpose of this article was to evaluate the bactericidal effect of PIPS with NaOCl in root canals with different widths or tapers.
Twenty-three maxillary first molars with three independent root canals were included in this study. The mesiobuccal (MB), distobuccal (DB), and palatal (P) root canals were prepared at sizes of #10/.02, #25/.02, and #25/.06, respectively. After being incubated with a bacterial suspension for 4 weeks, the specimen were irrigated with 2% NaOCl activated by conventional needle irrigation (CNI) (n = 10) or PIPS (n = 10). Three specimen were not treated (control group). Before and after irrigation, the presence of bacteria was assessed with an adenosine 5\'-triphosphate (ATP) assay kit and biofilms were assessed using confocal laser scanning microscopy and scanning electron microscopy.
In specimen prepared using PIPS irrigation, the ATP was reduced by more than 98%. When the root canal taper was 0.02, the size #25 root canals had a higher percentage of dead bacteria than the size #10 root canals in all regions (P < 0.05) in the PIPS group. When the root canal width was #25, the 0.02 taper group had a higher percentage of dead bacteria than the 0.06 taper group in the apical region (P < 0.05), except coronal and middle regions (P > 0.05). PIPS irrigation results in a greater percentage of dead bacteria and reduction of ATP in size #10/.02 root canals than CNI in size #25/.06 root canals in three regions (P < 0.05).
Increasing the width from #10 to #25 improves the bactericidal effect of PIPS in the root canal. Increasing the taper of the root canal from 0.02 to 0.06 at size #25 did not affect the bactericidal effects of PIPS. PIPS resulted in more dead bacteria in specimen with smaller tapers and root canal widths than CNI. PIPS can be used to clean the smear layer in the coronal region and open the dentin tubules.
Activation of irrigants with PIPS brought about significant bacterial reduction smaller tapers and width root canals compared to CNI, which was beneficial to prevent excessive loss of tooth tissue and conserve the structural integrity of teeth.

OBJECTIVE: This study aimed to compare the efficacy of silver nanoparticles (AgNPs) irrigating solution alone and following activation with photon-induced photoacoustic streaming (PIPS), photodynamic therapy (PDT) with indocyanine green (ICG), passive ultrasonic irrigation (PUI), and manual dynamic activation (MDA) method for elimination of Enterococcus faecalis (E. faecalis) from the root canal system.
METHODS: A total of 59 extracted human single-rooted teeth were collected and prepared. E. faecalis was inoculated into the root canals and incubated for 4 weeks. The teeth were then randomly divided into five experimental groups (n = 10): the AN group, irrigation with AgNPs alone; the AN/ICG/DL group, irrigation with AgNPs and ICG, then activation with diode laser; the AN/PIPS group, irrigation with AgNPs and activation with 0.3 W Er: YAG laser; the AN/MDA group, irrigation with AgNPs and activation with tapered gutta-percha; and the AN/PUI group, irrigation with AgNPs and activation with ultrasonic. Also, two control groups of irrigation with 2.5% sodium hypochlorite (n = 5) and no intervention (n = 4) were also used. Samples were collected from the dentinal chips before and after the intervention, and the percentage of reduction in colony count was calculated.
RESULTS: A significant reduction in E. faecalis colony count was noted in all groups (P < 0.05). Maximum reduction in colony count was noted in AN/PIPS and AN/PUI groups by 91.03 and 91.29%, respectively. Minimum reduction was noted in the AN group alone.
CONCLUSIONS: Activation with PUI and PIPS enhanced the efficacy of AgNPs irrigating solution for elimination of E. faecalis from the root canal system.
CONCLUSIONS: AgNPs activated by ultrasound or PIPS can be used as an adjunct for disinfection of the root canal system in endodontic treatment.

This study aimed to evaluate the effect of optimized irrigation with photon-induced photoacoustic streaming (PIPS) activation of different irrigants (distilled water or ethylenediaminetetraacetic acid [EDTA]) on smear layer removal, dentin microhardness, attachment morphology, and survival of stem cells of the apical papilla (SCAP) in an organotypic root canal model.
A total of 144 standardized root segments were randomly allocated into 6 groups for irrigation: (i) NaOCl group, (ii) NaOCl + EDTA group, (iii) NaOCl + PIPS (distilled water) group, (iv) NaOCl + PIPS (EDTA) group, (v) NaOCl + EDTA + PIPS (distilled water) group, and (vi) NaOCl + EDTA + PIPS (EDTA) group. Each group was divided into four subgroups for assessment: (i) dentin cleanliness; (ii) dentin microhardness; (iii) cell attachment morphology; and (iv) viable SCAP quantification.
Compared with the control groups, the NaOCl + EDTA + PIPS (EDTA) group showed higher efficiency in smear layer removal and in increasing SCAP viability with more stretched cellular morphology. There were no statistically significant differences in either smear layer removal effect, dentin microhardness, attachment morphology, or survival of SCAP among the other groups when optimized with PIPS (distilled water or EDTA) (P > 0.05).
Our findings indicated that irrigation optimized with PIPS activation of EDTA for 40 seconds was conducive to smear layer removal without additional dentin microhardness decrease. Additionally, this irrigation created more cell-friendly dentin conditioning than other approaches, which was beneficial for the attachment and survival of SCAP. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Antibacterial activity and tissue dilution of sodium hypochlorite (NaOCl) are improved by moderately heating the irrigant. Temperature can be risen by preheating or intracanal activation. To assess intracanal temperature development of NaOCl during irrigation activation and syringe activation (SI) in a closed system at 37°C, Type-K thermocouples were inserted close to the root canal of one human single-rooted maxillary canine at the apex and 5 and 10 mm from the apical foramen via drilled holes. The root was positioned in a plastic vial filled with alginate simulating surrounding biological structures. Experiments were performed in a closed environment at 37°C (n = 14): EA: EndoActivator (Dentsply Sirona), EDDY: EDDY (VDW), PUI: passive ultrasonic irrigation, PIPS: Photon-induced photoacoustic streaming (Fotona), S60: SI of 60°C-NaOCl, S45: SI of 45°C-NaOCl, and S20: SI of 20°C-NaOCl. S45, PUI and EDDY lead to minor intracanal temperature increases. EA and PIPS did not influence the intracanal temperature. SI with 60°C-NaOCl resulted in higher intracanal temperatures than activation systems. Temperature dissipation into simulated tissues buffered intracanal temperature changes.

In the field of endodontics, lasers have been used for a long time for the optimization of Endodontic irrigation in particular. The laser-activated irrigation (LAI) technique is based on the photomechanical effects of the lasers at low settings. They create specific cavitation phenomena and acoustic streaming in intracanal fluids. More recently, a new technique with a Er:YAG laser has been used with sub-ablative energy (20 mJ, 15 Hz) and ultra-short pulses (50 µs). This leads to intracanal cavitation and shockwaves as a result of photoacoustic and photomechanical effects. This phenomenon is called photon-induced photoacoustic streaming (PIPS). PIPS and Laser activated irrigation are described in the literature as a revolutionary and powerful method to activate the irrigant; however, systematic literature on this topic is missing. This review compares the literature on Er:YAG LAI and PIPS on endodontic irrigation with other irrigation methods. An article search was performed on the PubMed database using a series of keywords related to endodontic irrigation, including Er:YAG LAI and PIPS; 59 articles were selected for the review according to the inclusion and exclusion criteria. No in vivo study was found. The Er:YAG LAI and PIPS outperformed other methods in 33 of the 59 articles. There was a great variety in the study designs including bacterial incubation time, laser parameters, irrigation protocols, and irrigating solution used. The evidence suggests that the Er:YAG LAI and PIPS are promising in canal disinfection as well as debris and smear layer removal. However, the large variety in the study methods makes the results less significant. Further studies are needed to better evaluate the efficiency of these techniques, especially in vivo studies.

Objective: The aim of this in vitro study was to investigate the possible interactions between photon-induced photoacoustic streaming (PIPS™)-activated oxidizing agents and 2% chlorhexidine digluconate. Background data: There is no information about the safety of laser-activated oxidizing agents in combination usage with chlorhexidine gluconate. Materials and methods: Groups were designed as follows G1: 98% para-chloroaniline (PCA); G2: 2% chlorhexidine (CHX); G3: 5.25% sodium hypochlorite (NaOCl) +2% CHX; G4: 5.25% NaOCl (30 sec PIPS activated) +2% CHX; G5: 5.25% NaOCl (60 sec PIPS activated) +2% CHX; G6: 3.5% chlorine dioxide (ClO2) + 2% CHX; G7: 3.5% (ClO2) (30 sec PIPS activated) +2% CHX; G8: 3.5% (ClO2) (60 sec PIPS activated) +2% CHX. The laser-irrigation protocol was performed with an erbium:yttrium-aluminum-garnet laser with a wavelength of 2940 nm equipped with a 140 mm long endodontic fiber tip (PIPS) using 10 mJ at 15 Hz (0.15 W), per pulse operating outputs. Groups were analyzed with proton nuclear magnetic resonance spectroscopy, using PCA as an internal standard. Results: No free PCA was formed in any groups of mixtures or after PIPS activation. Conclusions: Mixing of 3.5% ClO2 and 2% CHX does not form bulky precipitates, unlike the mixture NaOCl + CHX. PIPS activation does not cause changes in reactions of oxidizing agents.

Objective: The aim of this study was to compare the efficacy of HyFlex EDM (Coltene/Whaledent, Altstätten, Switzerland) and ProTaper Universal Retreatment Nickel-Titanium (NiTi) Systems [The ProTaper Universal Retreatment (PTR), Dentsply Maillefer, Ballaigues, Switzerland] in the removal of the root canal filling materials with or without laser activated irrigation. Materials and methods: The root canals of 60 human mandibular premolars were instrumented with K files up to size 35 at a working length; the step-back procedure was performed in 1 mm increments up to size 50. Next, the teeth were obturated using the lateral compaction technique with gutta-percha and resin-based sealer, and they were randomly divided into two groups (n = 30) according to the retreatment systems: PTR and HyFlex EDM NiTi rotary files. Then, each group was divided into two subgroups (n = 15), laser [photon-induced photo-acoustic streaming (PIPS); Fotona, Ljubljana, Slovenia] activated irrigation and conventional needle irrigation group. Following these procedures, the specimens were evaluated using micro-computed tomography. Results: There was no significant difference between the instrumentation systems regarding the cleaning efficacy (χ2 = 0.754; p = 0.86). Additionally, PIPS method did not have a significant effect on the removal of the filling material compared to conventional needle irrigation. Conclusions: Both instrumentation systems were effective in removing the filling material, but neither was able to remove the filling material completely. PIPS method did not show a significant additional effect regarding the removal of filling material.