An interventional study of Photon-Induced Photoacoustic Streaming and Shock Wave Enhanced Emission Photoacoustic Streaming in Apical Periodontitis, sponsored by Inonu University. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Inonu University · Not applicable, Interventional, and Treatment
This study will compare three methods of activating the final irrigation solution in reducing living bacteria inside the root canals of teeth that require root canal retreatment because of apical periodontitis, an inflammatory condition of the tissues around the root tip. The three methods are photon-induced photoacoustic streaming (PIPS), shock wave-enhanced emission photoacoustic streaming (SWEEPS), and passive ultrasonic irrigation (PUI). Ninety adults requiring retreatment of a single-rooted, single-canal tooth will be randomly assigned to three groups; all treatment steps other than the activation method will be identical. Root canal samples will be collected at several stages of the single-visit treatment, and living bacteria will be counted using laboratory cultures. In addition, real-time PCR will be used to measure the relative amount of Enterococcus faecalis DNA compared with total bacterial DNA. Because PCR cannot distinguish living from dead bacteria, these molecular results will be interpreted as complementary to the culture findings.
Background: The main cause of persistent or secondary apical periodontitis in root canal-treated teeth is the persistence of bacteria in difficult-to-access areas of the root canal system. Irrigation activation aims to improve the delivery of irrigating solutions to these areas. PIPS and SWEEPS techniques using an Er:YAG laser generate pressure waves within the irrigating solution without placing the laser tip inside the root canal. A clinical study in teeth with primary apical periodontitis found no difference in bacterial reduction between SWEEPS and passive ultrasonic irrigation (PUI); however, that study used a molecular method that can also detect DNA from dead bacteria. The effects of these three methods on viable bacterial load in root canal retreatment cases have not been compared using culture.
Objective: To compare the efficacy of final irrigant activation with PIPS or SWEEPS versus PUI in reducing viable total intracanal bacteria and viable Enterococcus faecalis during single-visit nonsurgical root canal retreatment of single-rooted, single-canal teeth with apical periodontitis. A secondary objective is to evaluate changes in the relative quantity of E. faecalis DNA, normalized to total bacterial 16S rRNA, across sampling stages using real-time PCR.
Materials and Methods: Ninety patients will be allocated to the PIPS, SWEEPS, and PUI groups (n = 30 per group) using block randomization. Root canal filling material will be removed without solvents, and chemomechanical preparation will be performed using Reciproc Blue R40 and 5% NaOCl. A sterility control sample (S0) will be collected, and intracanal samples will be obtained after removal of the root canal filling (S1), after chemomechanical preparation (S2), and after final irrigant activation (S3). Group allocation will be revealed only after S2 sampling. In all groups, the type, concentration, volume, sequence, and total activation time of the irrigants will be identical (3 x 2 mL of 5% NaOCl, 20 seconds of activation each; total 60 seconds).
Samples will be transported to the microbiology laboratory in reduced transport fluid and processed within 2 hours. S1, S2, and S3 samples will be divided into culture and molecular aliquots; S0 will be analyzed by culture only. Viable total bacterial load and viable E. faecalis levels will be determined by culture and reported as CFU/mL. In the molecular aliquots, an E. faecalis-specific gene region and the universal bacterial 16S rRNA gene region will be targeted by real-time PCR; relative quantity will be calculated using the 2\^(-delta Ct) and 2\^(-delta delta Ct) methods. Laboratory personnel and the statistician will be blinded to group allocation.
Outcomes and Analysis: The primary outcome is the reduction in viable total bacterial load during final irrigant activation, calculated as log10 CFU/mL (S2) minus log10 CFU/mL (S3). This reduction will be compared among groups using the Kruskal-Wallis test, followed by Dunn's test with Holm correction. Secondary outcomes include the proportion of negative cultures at S3, reductions from S1 to S2 and from S1 to S3, changes in viable E. faecalis, and changes in the relative quantity of E. faecalis DNA determined by real-time PCR. Molecular findings will be interpreted as complementary to culture results, as real-time PCR cannot distinguish between viable and dead bacteria.
262 studies on the registry are indexed under Periapical Periodontitis; 66 are open to participants now.
This study's planned enrollment of 90 is above the median of 60 across 228 interventional studies indexed under Periapical Periodontitis.
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Exclusion Criteria:
Thirty participants will undergo standardized single-visit nonsurgical root canal retreatment. Following chemomechanical preparation, the final 5% NaOCl irrigant will be activated using photon-induced photoacoustic streaming (PIPS) with an Er:YAG laser (2940 nm; LightWalker ST-E Pro, Fotona d.o.o., Ljubljana, Slovenia).
Device: Photon-Induced Photoacoustic Streaming
Thirty participants will undergo standardized single-visit nonsurgical root canal retreatment. Following chemomechanical preparation, the final 5% NaOCl irrigant will be activated using shock wave-enhanced emission photoacoustic streaming (SWEEPS) with an Er:YAG laser (2940 nm; LightWalker ST-E Pro, Fotona d.o.o., Ljubljana, Slovenia).
Device: Shock Wave Enhanced Emission Photoacoustic Streaming
Thirty participants will undergo standardized single-visit nonsurgical root canal retreatment. Following chemomechanical preparation, the final 5% NaOCl irrigant will be activated using passive ultrasonic irrigation (PUI) with an ultrasonic device (Woodpecker DTE S6, Guilin Woodpecker Medical Instrument Co., Ltd., Guilin, China).
Device: Passive Ultrasonic Irrigation
After S2 sampling, 3 mL of 17% EDTA will be delivered with the needle 2 mm short of the working length and left for 3 minutes without activation, then aspirated, and the canal will be rinsed with 5 mL of sterile saline. The canal and pulp chamber will be filled with 2 mL of 5% NaOCl and activated for 20 seconds with an Er:YAG laser (2940 nm; LightWalker ST-E Pro, Fotona d.o.o., Ljubljana, Slovenia) in PIPS mode at 20 mJ, 15 Hz, 0.3 W and 50-microsecond pulse duration, with water and air spray off. A tapered PIPS 600/9 tip (600 micrometers, 9 mm) will be held stationary in the access cavity above the canal orifice without insertion into the canal. This will be repeated three times with fresh 2 mL of NaOCl (total 6 mL, 60 seconds of activation), keeping the pulp chamber filled throughout.
Also known as: PIPS
After S2 sampling, 3 mL of 17% EDTA will be delivered with the needle 2 mm short of the working length and left for 3 minutes without activation, then aspirated, and the canal will be rinsed with 5 mL of sterile saline. The canal and pulp chamber will be filled with 2 mL of 5% NaOCl and activated for 20 seconds with an Er:YAG laser (2940 nm; LightWalker ST-E Pro, Fotona d.o.o., Ljubljana, Slovenia) in AutoSWEEPS mode at 20 mJ, 15 Hz and 0.3 W, with water and air spray off. A Radial SWEEPS 600/9 tip (600 micrometers, 9 mm) will be held stationary in the access cavity above the canal orifice without insertion into the canal. This will be repeated three times with fresh 2 mL of NaOCl (total 6 mL, 60 seconds of activation), keeping the pulp chamber filled throughout.
Also known as: SWEEPS
After S2 sampling, 3 mL of 17% EDTA will be delivered with the needle 2 mm short of the working length and left for 3 minutes without activation, then aspirated, and the canal will be rinsed with 5 mL of sterile saline. The canal and pulp chamber will be filled with 2 mL of 5% NaOCl and activated for 20 seconds with a Woodpecker DTE S6 ultrasonic device (Guilin Woodpecker Medical Instrument Co., Ltd., Guilin, China) and an ED60 tip in Endo mode at power level 2. The tip will be positioned 2 mm short of the working length and activated without contacting the root canal walls. This will be repeated three times with fresh 2 mL of NaOCl (total 6 mL, 60 seconds of activation), keeping the pulp chamber filled throughout.
Also known as: PUI
Reduction in Viable Total Cultivable Intracanal Bacterial Load From S2 to S3
Viable total cultivable intracanal bacteria will be quantified by culture as colony-forming units per milliliter (CFU/mL). For each participant, the reduction will be calculated as log10 CFU/mL at S2 minus log10 CFU/mL at S3 and reported in log10 CFU/mL. The reduction will be compared among the PIPS, SWEEPS and passive ultrasonic irrigation groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (During the single treatment visit, from completion of chemomechanical preparation (S2) to immediately after final irrigant activation (S3).)
Reduction in Viable Total Cultivable Intracanal Bacterial Load From S1 to S2
Viable total cultivable intracanal bacteria will be quantified by culture as CFU/mL. For each participant, the reduction will be calculated as log10 CFU/mL at S1 minus log10 CFU/mL at S2 and reported in log10 CFU/mL. This outcome reflects bacterial reduction during the common chemomechanical preparation phase and will be compared among the three groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (During the single treatment visit, from root canal filling removal (S1) to completion of chemomechanical preparation (S2).)
Overall Reduction in Viable Total Cultivable Intracanal Bacterial Load From S1 to S3
Viable total cultivable intracanal bacteria will be quantified by culture as CFU/mL. For each participant, the overall reduction will be calculated as log10 CFU/mL at S1 minus log10 CFU/mL at S3 and reported in log10 CFU/mL. The overall reduction will be compared among the three groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (During the single treatment visit, from root canal filling removal (S1) to immediately after final irrigant activation (S3).)
Reduction in Viable Intracanal Enterococcus faecalis Load From S1 to S2
Viable Enterococcus faecalis will be quantified by culture on selective medium (Enterococcosel agar), with suspected colonies confirmed by biochemical tests, and expressed as CFU/mL. For each participant, the reduction will be calculated as log10 CFU/mL at S1 minus log10 CFU/mL at S2 and reported in log10 CFU/mL. The reduction will be compared among the three groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (During the single treatment visit, from root canal filling removal (S1) to completion of chemomechanical preparation (S2).)
Reduction in Viable Intracanal Enterococcus faecalis Load From S2 to S3
Viable Enterococcus faecalis will be quantified by culture on selective medium (Enterococcosel agar), with suspected colonies confirmed by biochemical tests, and expressed as CFU/mL. For each participant, the reduction will be calculated as log10 CFU/mL at S2 minus log10 CFU/mL at S3 and reported in log10 CFU/mL. The reduction will be compared among the three groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (During the single treatment visit, from completion of chemomechanical preparation (S2) to immediately after final irrigant activation (S3).)
Overall Reduction in Viable Intracanal Enterococcus faecalis Load From S1 to S3
Viable Enterococcus faecalis will be quantified by culture on selective medium (Enterococcosel agar), with suspected colonies confirmed by biochemical tests, and expressed as CFU/mL. For each participant, the overall reduction will be calculated as log10 CFU/mL at S1 minus log10 CFU/mL at S3 and reported in log10 CFU/mL. The overall reduction will be compared among the three groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (During the single treatment visit, from root canal filling removal (S1) to immediately after final irrigant activation (S3).)
Percentage of Participants With Culture-Positive Enterococcus faecalis After Final Irrigant Activation (S3)
A sample will be considered positive if at least one colony is detected on Enterococcosel agar and confirmed as Enterococcus faecalis by biochemical tests. The outcome is reported as the percentage of participants with an E. faecalis-positive S3 sample and will be compared among the three groups. S1 denotes sampling after removal of the root canal filling material and before chemomechanical preparation; S2, after chemomechanical preparation and before final irrigant activation; S3, immediately after final irrigant activation.
Time frame: Day 1 (Immediately after final irrigant activation (S3), during the single treatment visit.)
Plan to share: No — Individual participant data will not be made publicly available because participants' informed consent and the ethics committee approval do not cover data sharing with third parties. Aggregated results will be reported in the publication. De-identified data may be made available by the corresponding author upon reasonable request, subject to approval by the institutional ethics committee.
Start is estimated for Nov 2026; primary completion for May 2027, 6 months later.
Of 157 non-industry interventional studies with no phase under Periapical Periodontitis, half reached primary completion within 12 months of starting (the median), counting those still running; a quarter within 6 and three quarters within 19. This study's planned 6 months is below that.
Counting every sponsor, half of 158 studies reached it within 12 months; a quarter within 6 and three quarters within 19.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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