Photoacoustic Streaming Research Articles

Real-time intracanal temperature measurement comparing mechanically and laser-activated irrigation to syringe irrigation.

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 10mm 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.

The Antibacterial Effects of New N-Alkylpyridinium Salts on Planktonic and Biofilm Bacteria.

An increasing microbial resistance to known antibiotics raises a demand for new antimicrobials. In this study the antimicrobial properties of a series of new N-Alkylpyridinium quaternary ammonium compounds (QACs) with varying alkyl chain lengths were evaluated for several nosocomial pathogens. The chemical identities of the new QACs were determined by NMR, LC-MS, and HRMS. All the planktonic bacteria tested were susceptible to the new QACs as evaluated by MIC and MBC assays. The antimicrobial effect was most pronounced against Staphylococcus aureus clinical isolates. Live/dead staining CLSM was used to test the effectiveness of the QACs in biofilms. The effectiveness was up to 10-fold lower than in the plankton. When QACs were used as irrigants in Er:YAG – SSP photoacoustic steaming, their effectiveness significantly increased. The combined use of irrigants and photoacoustic streaming increased biofilm removal from the surface and increased the killing rate of the cells remaining on the surface. This may allow for a shorter chemical exposure time and lower dosage of QACs used in applications. The results demonstrate that the new QACs have potential to be applied as antibacterial compounds effective against planktonic and biofilm bacteria as well as irrigants in removal of difficult-to-reach biofilms.

Characteristics of the Irrigant Flow in a Simulated Lateral Canal Under Two Typical Laser-Activated Irrigation Regimens.

Photon-induced photoacoustic streaming (PIPS) and shockwave-enhanced emission photoacoustic streaming (SWEEPS) are two promising laser-activated irrigation (LAI) methods for root canal irrigation. Their performance in driving irrigant flush in a complex root canal system will be evaluated by microscale particle image velocimetry (μPIV) measurement and will be compared with that of ultrasonic-activated irrigation (UAI). A μPIV system with 7 μm fluorescent tracer particles was adopted to measure two-dimensional (2D) velocity fields around the junction region, with a size of 1.8 mm × 1.5 mm, between one main canal and one lateral canal in an endodontic training block, which was driven by SWEEPS (Er:YAG laser) operating at 15 Hz and 20 mJ. The flow field driven by PIPS (Er:YAG laser) at the same frequency and energy, as well as by UAI (with non-cutting insert) operating at 40% unit power, was also measured for a direct comparison. It was found that both SWEEPS and PIPS can activate a so-called "breath mode" during the irrigation. Namely, the induced irrigant flush presented a back-and-forth oscillation along both the main canal and the lateral one. The maximum flow speed in the lateral canal was observed to be up to 10 m/s in the SWEEPS modality, while reduced to around 7 m/s in the PIPS modality. The penetration length in the lateral canal in both modalities was estimated to be larger than 1 mm. In comparison, the flow field induced by UAI was characterized as irregular vortical structures, the maximum flow speed in the lateral canal was 0.15 m/s and significantly lower than LAI (P < 0.01), and the penetration length was less than 300 μm and lower than LAI (P < 0.05). Compared to UAI, PIPS, and SWEEPS are more capable of delivering the irrigant deeper into the lateral canal. Furthermore, the back-and-forth flush in the breath mode is ideal for removing debris during irrigation. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Comparison of apical debris extrusion using EDDY, passive ultrasonic activation and photon-initiated photoacoustic streaming irrigation activation devices.

The study aimed to determine the effect of different irrigation activation systems on the amount of apical debris extrusion in mandibular molar teeth with curved root canals. Sixty extracted mandibular molar teeth were instrumented with HyFlex EDM system and divided into four groups according to irrigation techniques: passive ultrasonic irrigation (PUI), EDDY, photon-initiated photoacoustic streaming (PIPS) and manual irrigation (MI). After the final irrigation, the extruded irrigants were collected into Eppendorf tubes of known weights. The amount of extruded debris was obtained by subtracting the weight from the initial weight of the tube. The Kruskal-Wallis test was used for statistical analysis. EDDY caused significantly more debris extrusion than the other irrigation activation systems (P<0.001). PUI caused less apical debris extrusion but there was no statistical difference between PUI, PIPS and MI (P>0.05). The EDDY activation system was associated with the highest amount of debris extrusion in curved root canals.

ANTIMICROBIAL EFFECTIVENESS OF PHOTON-İNDUCED PHOTOACOUSTIC STREAMING, PHOTOACTIVATED DISINFECTION AND SODIUM HYPOCHLORITE IRRIGATION IN INFECTED ROOT CANALS

Aim: This study aimed to evaluate the antibacterial and antifungal effects of different disinfection methods for infected root canals with Enterococcus faecalis or Candida albicans in vitro. Material and Methods: Hundred extracted, single-rooted human teeth with straight root canals were selected. After chemo-mechanical preparation of the root canals, except of those in the negative control group, contamination was performed using Enterococcus faecalis or Candida albicans for 7 days. The infected teeth were divided into three subgroups (n = 15) according to the disinfection method applied: photo‑activated disinfection, photon-induced photoacoustic streaming and 2.5% sodium hypochlorite irrigation. Microbial samples were collected from the root canals before and after disinfection. Hundred Colony forming units were counted, and data were statistically analysed. Results: All experimental groups showed significant reduction of Enterococcus faecalis and Candida albicans. Photon-induced photoacoustic streaming and sodium hypochlorite irrigation had similar antimicrobial effect, which was higher than photo‑activated disinfection for both microorganisms (p < 0.05). Conclusion: None of the testing methods for root canal disinfection was able to achieve complete elimination of microorganisms. However, the results of this study state that photon-induced photoacoustic streaming, photo‑activated disinfection and 2.5% NaOCl has significant antimicrobial effect against Enterococcus faecalis and Candida albicans biofilms in root canals. Key words: Candida albicans, Enterococcus faecalis, Photodynamic Therapy, Root Canal, Sodium Hypochlorite Foton ile İndüklenen Fotoakustik Dalgalanma Tekniği, Işıkla Aktive Edilen Dezenfeksiyon ve Sodyum Hipokloritin Enfekte Kök Kanallarındaki Antimikrobiyal Etkileri Öz Amaç: Bu çalışmada, Enterococcus faecalis veya Candida albicans ile enfekte edilmiş kök kanallarında farklı dezenfeksiyon yöntemlerinin antibakteriyel ve antifungal etkilerinin in vitro olarak incelenmesi amaçlanmıştır. Gereç ve yöntem: Çalışmada yüz adet çekilmiş, tek köklü, düz kanallı diş kullanıldı. Kök kanallarının kemo-mekanik preparasyonunun ardından, negatif kontrol grubu haricindeki dişler 7 gün boyunca Enterococcus faecalis veya Candida albicans ile enfekte edildi. Enfekte edilen dişler uygulanan dezenfeksiyon yöntemine göre ışıkla aktive edilen dezenfeksiyon, fotonla indüklenen fotoakustik dalgalanma tekniği veya %2.5 sodyum hipoklorit irigasyonu uygulanmak üzere üç alt gruba (n = 15) ayrıldı. Dezenfeksiyon öncesi ve sonrasında kök kanallarından mikrobiyal örnekler alındı. Koloni oluşturan birimler sayıldı ve veriler istatistiksel olarak analiz edildi. Bulgular: Tüm deney gruplarında, Enterococcus faecalis ve Candida albicans mikroorganizmalarında önemli ölçüde azalma gözlendi. Fotonla indüklenen fotoakustik dalgalanma tekniği ve sodyum hipoklorit irigasyonu benzer antimikrobiyal etkiye sahip bulunurken (p>0.05), her iki grubun gösterdiği antimikrobiyal etki ışıkla aktive edilen dezenfeksiyondan iki mikrooganizma türü için de daha yüksek bulundu (p<0.05). Sonuç: Uygulanan dezenfeksiyon yöntemlerinin hiçbiri ile mikroorganizmaların tümünün elimine edilmesi mümkün olmadı. Bununla birlikte, bu çalışmanın sonuçları; foton ile indüklenen fotoakustik dalgalanma tekniği, ışıkla aktive edilen dezenfeksiyon ve %2.5 sodyum hipokloritin kök kanallarındaki Enterococcus faecalis ve Candida albicans biofilmlerinde önemli ölçüde antimikrobiyal etkinliğe sahip olduğunu göstermektedir. Anahtar Kelimeler: Candida albicans, Enterococcus faecalis, Fotodinamik Terapi, Kök Kanalı, Sodyum Hipoklorit

Retreatability of Bioceramic Endodontic Sealers: a Review.

In 2009 a new type of endodontic sealers was introduced to the market. The so called "bioceramic" sealers are a promising alternative to the present golden standard of root canal fillings. Now a decade later, still very little is known about the ability to remove these sealers in cases of non-surgical endodontic retreatment (NSER). There are only a limited number of articles that provide such information. The commonly used hand files are not efficient in removing thoroughly the sealer from the main canal walls. Machine driven files are much easier and faster alternative to the hand ones, but are still not able to ensure complete removal. Although ultrasonics can be applied only in the straight portion of the main canal, they raise the efficacy of sealer removal. Photon-initiated photoacoustic streaming (PIPS) is another way to enhance the removal of bioceramics. Solvents like chloroform and orange oil are effective in softening gutta-percha, but not the bioceramics. This article reviews the available scientific data concerning removal of bioceramic materials in the context of a NSER.

The Efficiency of the Er: YAG Laser and PhotonInduced Photoacoustic Streaming (PIPS) as an Activation Method in Endodontic Irrigation: A Literature Review.

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.

Proton Nuclear Magnetic Resonance Spectroscopy Analysis of Mixtures of Chlorhexidine with Different Oxidizing Agents Activated by Photon-Induced Photoacoustic Streaming for Root Canal Irrigation.

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.

Efficacy of the photon-initiated photoacoustic streaming combined with different solutions on Enterococcus faecalis in the root canals.

This study aimed to evaluate the efficacy of different irrigation solutions used in photon-initiated photoacoustic streaming (PIPS) or conventional needle irrigation (CNI) for eradication of Enterococcus faecalis from artificial root canals. Altogether, 240 artificial root canal samples were included. The models were split and incubated for 2 days to allow formation of E. faecalis biofilm. The models were randomly divided into two groups (n = 120): CNI and laser-activated irrigation (LAI). Each group was divided into six subgroups according to different irrigation solutions: distilled water, 1% sodium hypochlorite (NaOCl), 2% NaOCl, 5.25% NaOCl, MTAD, and chlorhexidine, respectively. After irrigation, half of the samples (n = 10) were assessed immediately, and the other half of the samples (n = 10) were incubated for 6 hr. Bacterial suspensions were obtained from all samples before and after irrigation, and after incubation, and were quantified adenosine 5'-triphosphate (ATP) assay kit. The biofilms were examined using fluorescent microscopy and analyzed by Image Pro Plus software. Significant reduction of ATP, average fluorescence density after irrigation, and growth after incubation was obtained in LAI group than in CNI group (p < .05). LAI can improve bacteriostasis effect of 2% NaOCl (p < .05). PIPS improved the antibacterial effect of the 2% NaOCl used in root canal therapy.

Effect of different laser-assisted irrigation activation techniques on apical debris extrusion

Objective: The aim of this study was to compare apical debris extrusion when neodymium-doped yttrium aluminium garnet (Nd:YAG) lasers, erbium-doped yttrium aluminium garnet (Er:YAG) or photon-induced photoacoustic streaming (PIPS) are used for irrigation activation.Materials and methods: A total of 60 extracted human mandibular premolar teeth have similar dimensions were included and the samples were split into four groups according to the irrigation technique (n = 15): conventional needle irrigation, PIPS, Er:YAG and Nd:YAG. ProTaper Universal system up to F4 was used for root canal instrumentation. Bidistilled water was used as an irrigation solution during instrumentation and irrigation activation. Apically extruded debris was collected into preweighed Eppendorf tubes during instrumentation and irrigation activation procedures. The tubes were then kept in an incubator at 70 °C for 5 days. The initial weight of the tube was subtracted from the final weight and the result was recorded as the weight of dry extruded debris. The data were evaluated statistically using a one-way ANOVA test followed by least significant difference post hoc test (p < .05).Results: Conventional needle irrigation caused significantly less debris extrusion than laser-assisted irrigation activation groups (p < .05). Laser-assisted irrigation activation groups caused statistically similar debris extrusion (p > .05).Conclusion: Laser-assisted irrigation activation techniques caused more debris extrusion when compared to conventional needle irrigation.

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.

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). 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 15μm. Mesial canals were prepared up to aProTaper F3 rotary file, and distal canals were prepared up to aProTaper 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 15.5mL of 1% NaOCl for each tooth with an activation time of 3×30s. 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%. 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. 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.

The efficacy of ultrasonic and PIPS (photon-induced acoustic streaming) irrigation to remove artificially placed dentine debris plugs out of an artificial and natural root model.

The aim was to validate an artificial resin 'root canal wall groove model' (RCWGM) mimicking the situation of natural roots with a groove of identical dimensions on debris removal out of these grooves, and to evaluate Erbium 'laser-activated irrigation' (LAI) with two conical tips at PIPS (photon-induced photoacoustic streaming) settings, with different activation times and different root canal positions on debris removal out of the grooves. A split RCWGM was used (resin blocks and roots of maxillary canines) with a canal size 40/0.06. The grooves in the apical third were filled with stained dentinal debris. Seventeen irrigation protocols (n = 20) were used: syringe-needle irrigation (3× 20 s), manual dynamic activation (1× 60 s), ultrasonically activated irrigation (UAI) with 25/25 Irrisafe (3× 20 s) and LAI (2940 nm Er:YAG) with X-Pulse or PIPS tips at PIPS settings (20 mJ, 50 μs, 20 Hz) and with the fibre (IN) or (OUT) the canal: IN during 1× 20 s, and OUT during 1× 20 s, 2× 20 s, 3× 20 s, 30 s, 2× 30 s and 1× 60 s. The quantity of remaining dentine debris in the groove was evaluated on a numerical scale. Statistical analysis was performed by means of proportional odds logistic regression, equivalence testing and Wald tests. The level of significance was set at 0.05. Resin models and the RCWGM with natural teeth can be called equivalent (log odds ratio 0.185). There were mostly no statistically significant differences for debris removal between UAI and LAI (p > 0.05) and between LAI with PIPS and X-Pulse (p > 0.05). Although not statistically different, the numbers of completely cleaned grooves were higher with LAI than with UAI for a 1-min activation, confirming findings from other studies. There is no difference in cleaning efficacy between X-Pulse and PIPS tips at PIPS settings.

Impact of Different Irrigant Agitation Methods on Bacterial Elimination from Infected Root Canals

Activation techniques are essential for root canal disinfection but may result in incomplete removal of bacteria. The aim of our study was to assess the antibacterial action of sonically, ultrasonically and laser-activated irrigation and 5.25% sodium hypochlorite (NaOCl) on Enterococcus faecalis in an infected tooth. Forty-four extracted mandibular premolars were mechanically prepared, sterilized, and inoculated with E. faecalis for 1 week. Bacterial counts after inoculation were evaluated in 4 randomly chosen teeth, remaining root canals were divided into 4 groups. Group A: laser-activated irrigation by photon-induced photoacoustic streaming, Group B: the sonic irrigation by EDDY, Group C: ultrasonic irrigation by EndoUltra, and Group D: 5.25% NaOCl. Colony forming unit (CFU) counts were measured and Kolmogorov–Smirnov, Wilcoxon, Kruskal–Wallis and Mann–Whitney tests were used to determine differences. The mean of CFU was found to significantly decrease in group D, 2110 ± 1015.93 (p < 0.001). Changes in measurement levels followed the same trend over time in groups A 27.40 ± 30.15, B 81.3 ± 85.68 and C 44.40 ± 67.12 (p = 0.141). The average CFU after irrigation in all groups was significantly greater than 0. Within the limitations of this study, all activation techniques were superior to NaOCl 5.25% in reducing E. faecalis from the infected tooth model.

Efficacy of Two Different Nickel-Titanium Rotary Systems in Retreatment Procedure With or Without Laser-Activated Irrigation: An In Vitro Study.

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.

Postoperative Quality of Life Following Conventional Endodontic Intracanal Irrigation Compared with Laser-Activated Irrigation: A Randomized Clinical Study.

Objective: The aim of this randomized clinical study was to evaluate the effect of laser-activated irrigation using a photon-induced photoacoustic streaming (PIPS) technique on postoperative pain following completion of root canal obturation. Methods: Fifty-six patients were enrolled in this randomized clinical trial. Fifty-six healthy premolars or molars with asymptomatic irreversible pulpitis, symptomatic irreversible pulpitis, or symptomatic pulpal necrosis, with or without apical periodontitis, were mechanically prepared for endodontic treatment and divided into two groups. Patients were randomly allocated to treatment groups. In the positive control group G1, the final irrigation with 2 cc of 5.25% sodium hypochlorite (NaOCl) was achieved using a 27G needle, introduced into the canal to a distance of 5 mm from the predetermined working length. In the experimental group G2, the root canals were irrigated with 17% ethyldiamine tetric acid (EDTA) and 5.25% NaOCl following the PIPS protocol, using an Er:YAG 2940 nm laser (LightWalker ATS®; Fotona, Slovenia) with a 600 μm diameter tip and operating parameters of 20 mJ per pulse, 15 Hz frequency, 0.3 W average power, and a 50-μs pulse duration. Postoperatively, the patients were advised to take a minor analgesic (ibuprofen 400 mg) in the event of pain perception. Postoperative pain levels were assessed after 24, 48, and 72 h and 7 days through the use of a Visual Analogue Scale questionnaire, completed by each patient. Data were analyzed using Kolmogorov-Smirnov, Fisher Exact, Chi square, Mann-Whitney test, and Friedman's test. The level of significance was set at α = 0.05. Results: There was no significant difference between the laser-irradiated group and the control group (p < 0.5). Laser activation of irrigating solutions did not increase postoperative pain. Conclusions: The outcome of this investigation indicated that PIPS was as effective as conventional irrigation in relation to postoperative pain, making this activation technique interesting to use for supplementary root canal disinfection.

Penetration depth of irrigants into root dentine after sonic, ultrasonic and photoacoustic activation.

To compare penetration depths of endodontic irrigants into the dentinal tubules of extracted teeth when using several activation methods. The root canals of 90 extracted human teeth were prepared to size 40, .06 taper. The straight and round-shaped root canals were distributed randomly into six groups, and final irrigation was performed with EDTA and sodium hypochlorite as follows: (I) manual dynamic activation, (II) Ultrasonic, (III) Sonic, (IV) PIPS (photon-induced photoacoustic streaming, (V) SWEEPS (shock-wave enhanced emission photoacoustic streaming) and (0) control without final irrigation or activation. Subsequently, methylene blue was inserted into the canals and activated according to the groups (I-V). Teeth were sectioned horizontally, imaged under a light microscope, and dye penetration depths were measured in six sections per tooth and 24 points on a virtual clock-face per section. Data were analysed statistically by nonparametric tests for whole teeth and separately for coronal, middle and apical thirds. Penetration of dye into the dentinal tubules was lowest for the controls. Median penetration depths amounted to 700-900μm for groups I-V with differences in the apical thirds between group I and the other test groups. Minimum penetration depths were significantly greater for PIPS in the apical thirds (P≤0.046). Greater penetration depths occurred in the apical thirds for ultrasonic, sonic and laser-induced activation compared to manual dynamic activation. PIPS was associated with deeper penetration of irrigants. The novel SWEEPS mode did not increase irrigant penetration.

Gold-implanted plasmonic quartz plate as a launch pad for laser-driven photoacoustic microfluidic pumps

Enabled initially by the development of microelectromechanical systems, current microfluidic pumps still require advanced microfabrication techniques to create a variety of fluid-driving mechanisms. Here we report a generation of micropumps that involve no moving parts and microstructures. This micropump is based on a principle of photoacoustic laser streaming and is simply made of an Au-implanted plasmonic quartz plate. Under a pulsed laser excitation, any point on the plate can generate a directional long-lasting ultrasound wave which drives the fluid via acoustic streaming. Manipulating and programming laser beams can easily create a single pump, a moving pump, and multiple pumps. The underlying pumping mechanism of photoacoustic streaming is verified by high-speed imaging of the fluid motion after a single laser pulse. As many light-absorbing materials have been identified for efficient photoacoustic generation, photoacoustic micropumps can have diversity in their implementation. These laser-driven fabrication-free micropumps open up a generation of pumping technology and opportunities for easy integration and versatile microfluidic applications.

Deep disinfection and tubular smear layer removal with Er:YAG using photon-induced photoacoustic streaming (PIPS) contra laser-activated irrigation (LAI) technics

PurposeThis in vitro laboratory study assessed the efficacy of the laser in deep disinfection and smear layer removal with 2940-nm erbium:yttrium aluminum garnet (Er:YAG) laser. The purpose was to evaluate the efficacy of a conical and stripped Er:YAG tip using PIPS (photon-induced photo acoustic streaming) in root canals compared with end firing Preciso tip using LAI (laser-activated irrigation).MethodsThirty extracted single-rooted upper teeth were divided in three groups for smear layer removal: using PIPS and Preciso with the third as the control group. After irradiation methods with different erbium tips, the roots were longitudinally split for SEM observation. The root canals were then scanned separately in each specimen in all three thirds—coronal, middle, and apical. The remaining smear layer was evaluated with the Hülsmann score (Hülsmann et al., J Endod 23:301–306, 1997).ResultsIn the coronal third of the canal, both the PIPS and the Preciso group scored significantly better when equaled with the control group. In the middle third, the PIPS group got the smallest score, which was meaningfully different from that of the Preciso and the control groups. Preciso scored higher in the apical third, in comparison to the control group and PIPS group. Statistically significant alterations were found.ConclusionsThis SEM study showed that Er:YAG used with PIPS and Preciso tips, which generate cavitation in the irrigant, did not enhance the removal of the smear layer from dentin tubules from the apical part of a straight root canal when used only with saline solution as irrigant.

Does the Photon-Induced Photoacoustic Streaming Activation of Irrigation Solutions Alter the Dentin Microhardness?

Objective: The aim of this in vitro study was to evaluate the efficacy of photon-induced photoacoustic streaming (PIPS) activation of sodium hypochlorite (NaOCl), chlorhexidine (CHX) or ethylenediaminetetraacetic acid (EDTA) on the dentin microhardness and to assess the compositional changes of root dentin. Background data: It is still unclear whether PIPS activation of irrigants alters the dentin microhardness and mineral content of dentin. Materials and methods: Root canals of 72 extracted single-rooted teeth were prepared and teeth were fixed in microcentrifuge tubes with silicone impression material. After setting of the silicone, teeth were removed and split longitudinally in buccolingual direction. One half was used as control (pretreatment) while the other was placed into the tube (posttreatment). Then specimens were divided into six test groups (three with and three without PIPS activation). The irrigants tested were 2.5% NaOCl, 17% EDTA, and 2% CHX. Experimental tooth specimens were irrigated with 6 mL of test solution, with additional PIPS activation applied to the PIPS groups. Then specimens were subjected to Vickers microhardness testing. Percentage change of microhardness was calculated. Energy dispersive X-ray spectroscopy (SEM-EDX) was performed to measure element content. Results: Among the irrigant-alone groups, NaOCl and CHX did not alter the dentin microhardness, whereas statistically lower microhardness values were obtained in EDTA group. Chemical composition of dentin was affected from all irrigants used. PIPS activation led to no additional alteration in dentin microhardness. PIPS significantly increased the phosphorus level in NaOCl group. Conclusions: Dentin microhardness was significantly affected by the irrigation solution, not by the PIPS activation.

Estratégias para otimizar a remoção da camada de smear do sistema de canais radiculares

Objetivo: avaliar os diferentes métodos de agitação da solução de irrigação com base nos dados da literatura existente, comparando o uso de EndoActivator, EndoVac, sistema Easy Clean, Xp-Endo Finisher, Fluxo Fotoacústico Induzido por Fótons (PIPS) e Irrigação Ultrassônica Passiva (PUI). ) associado a agentes químicos na remoção da smear layer do RCS. Material e Métodos: Foram selecionados 28 artigos de periódicos, 2 livros, 2 monografias e 6 dissertações sobre as diferentes alternativas para a remoção de smear layer do RCS nas bases de dados PUBMED - National Institutes of Health dos Estados Unidos da National Library of Medicine; SCIELO - Scientific Eletronic Library Online e MEDLINE - MedLars Online. Resultados: como uma alternativa de remoção da smear layer para melhorar a sanitização do RCS e aumentar a taxa de sucesso do tratamento endodôntico, diferentes técnicas de irrigação têm sido propostas, incluindo a agitação da solução de irrigação de maneira mecânica, sonora ou ultra-sônica, Instrumentos Ni-Ti, plásticos e energia laser. Conclusão: muitos estudos comprovam a eficácia dos diferentes métodos de agitação da solução irrigadora na remoção da smear layer, contribuindo para o processo de sanitização do sistema de canais radiculares.