Effects of Different Activation Techniques on Antimicrobial Photodynamic Therapy in Apical Periodontitis

November 4, 2026 updated by: Nihan Çelik Uzun, Karadeniz Technical University

Molecular and Clinical Evaluation of the Effects of Antimicrobial Photodynamic Therapy Applied Using Different Activation Techniques on the Microbiota and Host Response in Previously Root Canal-Treated Teeth With Apical Periodontitis

This randomized clinical trial aims to investigate the effects of different intracanal methylene blue agitation techniques used during antimicrobial photodynamic therapy (aPDT) on root canal microbiota, host inflammatory responses, postoperative pain, and periapical healing in previously root canal-treated teeth with asymptomatic apical periodontitis.

A total of 60 participants will be randomly allocated to four groups (15 participants per group): aPDT without additional methylene blue agitation (control), aPDT with standard needle irrigation(SNI), aPDT with passive ultrasonic irrigation (PUI), and aPDT with Er,Cr:YSSG laser-assisted irrigation (LAI).

All participants will undergo nonsurgical root canal retreatment. Methylene blue will be used as the photosensitizing agent, and photodynamic light irradiation will be performed using the LED FotoSan device in all groups.

Root canal samples will be collected at three treatment stages to investigate changes in microbial communities and inflammatory markers. Shotgun metagenomic sequencing will be performed in a subset of participants, while selected inflammatory cytokines will be measured using enzyme-linked immunosorbent assay (ELISA).

Postoperative pain and radiographic periapical healing will also be evaluated during follow-up.

The study aims to determine whether different methylene blue agitation techniques influence the microbiological, inflammatory, and clinical outcomes of antimicrobial photodynamic therapy during root canal retreatment.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This randomized clinical trial will investigate the molecular, microbiological, inflammatory, and clinical effects of different intracanal methylene blue agitation techniques used during antimicrobial photodynamic therapy (aPDT) in previously root canal-treated permanent teeth with asymptomatic apical periodontitis.

A total of 60 participants will be randomly allocated to four groups (n=15 per group):

Control group: aPDT without additional intracanal methylene blue agitation.

Standard needle irrigation (SNI) group: aPDT with conventional syringe agitation of methylene blue.

Passive ultrasonic irrigation (PUI) group: aPDT with passive ultrasonic agitation of methylene blue.

Laser-activated irrigation (LAI) group: aPDT with Er,Cr:YSSG laser-assisted agitation of methylene blue.

All participants will undergo nonsurgical root canal retreatment, including removal of the previous root canal filling material and chemomechanical preparation. Methylene blue will be introduced into the root canal system as the photosensitizing agent. The assigned intracanal agitation protocol will then be performed, followed by photodynamic light irradiation using the FotoSan device in all groups.

Root canal samples will be collected at three stages: S1, after removal of the previous root canal filling material; S2, after chemomechanical preparation; and S3, following antimicrobial photodynamic therapy.

Shotgun metagenomic sequencing will be performed in a subset of 24 participants, including eight participants from each of the SNI, PUI, and LAI groups. The analysis will investigate microbial taxonomic composition, microbial diversity, functional pathways, antimicrobial resistance genes, and virulence-associated factors.

Host inflammatory responses will be evaluated in all four study groups by measuring interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α) using enzyme-linked immunosorbent assay (ELISA).

Postoperative pain will be assessed using a visual analog scale (VAS) at predefined intervals following treatment. Periapical healing will be evaluated radiographically during the follow-up period.

Within-group changes across sampling points and between-group differences will be evaluated to determine the influence of intracanal methylene blue agitation techniques on microbial communities, host inflammatory responses, postoperative pain, and periapical healing

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Nihan Çelik Uzun, Assistant Professor
  • Phone Number: +90 4623774813 +90 5557256407
  • Email: nihancelik@ktu.edu.tr

Study Locations

  • Turkey (Türkiye)
    • Ortahisar
      • Trabzon, Ortahisar, Turkey (Türkiye)
        • Recruiting
        • Karadeniz Technical University Faculty of Dentistry
        • Contact:
        • Principal Investigator:
          • Nihan ÇELİK UZUN, Assistant Professor

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Adults aged 18-65 years.
  • No history of systemic disease.
  • Non-smokers.
  • Not pregnant or breastfeeding.
  • Provision of written informed consent.
  • Willingness to attend follow-up appointments for 12 months

Exclusion Criteria:

  • Teeth with internal or external root resorption.
  • Teeth with moderate or severe root canal curvature.
  • Teeth with open apices.
  • Teeth with periodontal probing depths ≥4 mm.
  • Teeth in which adequate rubber dam isolation cannot be achieved.
  • Teeth considered non-restorable.
  • Teeth requiring post retention.
  • Teeth with radiographically determined periapical lesions larger than 5.
  • Systemic antibiotic or anti-inflammatory medication use within the preceding month.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Control - aPDT Without Additional Activation

Participants will receive antimicrobial photodynamic therapy using methylene blue without additional intracanal agitation, followed by FotoSan light irradiation
Procedure: Control - aPDT Without Additional Activation

All participants will receive antimicrobial photodynamic therapy (aPDT) using methylene blue as the photosensitizer, followed by photodynamic light irradiation with the FotoSan device. The groups will differ according to the intracanal activation technique applied to methylene blue.
Experimental: Standard Needle Irrigation (SNI)

Participants will receive antimicrobial photodynamic therapy (aPDT) with intracanal agitation of methylene blue using a standard irrigation needle with back-and-forth movements, followed by photodynamic light irradiation using the FotoSan device.
Procedure: Standard Needle Irrigation (SNI)

Methylene blue will be agitated within the root canal using a standard irrigation needle with back-and-forth movements before photodynamic light irradiation with the FotoSan device.
Experimental: Passive Ultrasonic Irrigation (PUI)

Participants will receive antimicrobial photodynamic therapy (aPDT) with intracanal activation of methylene blue using passive ultrasonic irrigation, followed by photodynamic light irradiation using the FotoSan device.
Procedure: Passive Ultrasonic Irrigation (PUI)

Methylene blue will be activated within the root canal using passive ultrasonic irrigation before photodynamic light irradiation with the FotoSan device.
Experimental: Laser-Activated Irrigation (LAI)

Participants will receive antimicrobial photodynamic therapy (aPDT) with intracanal activation of methylene blue using an Er, Cr:YSGG laser-assisted irrigation technique, followed by photodynamic light irradiation using the FotoSan device
Procedure: Laser-Activated Irrigation (LAI)

ethylene blue will be activated within the root canal using an Er,Cr:YSGG laser-assisted irrigation technique before photodynamic light irradiation with the FotoSan device

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Pain Intensity Assessed Using a Visual Analog Scale (VAS)
Time Frame: Up to 7 days after treatment (24 hours, 72 hours, and day 7)

Postoperative pain intensity will be assessed using a 100-mm Visual Analog Scale (VAS), ranging from 0 (no pain) to 100 (unbearable pain). Participants will record their pain intensity at 24 hours, 72 hours, and 1 week after treatment. Mean VAS scores at each time point will be compared among the four treatment groups.
Up to 7 days after treatment (24 hours, 72 hours, and day 7)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Periapical Radiographic Healing Assessed Using the Periapical Index (PAI)
Time Frame: From baseline through 12 months after treatment (baseline, immediately post-treatment, month 6, and month 12)

Periapical radiographic healing will be assessed using digital periapical radiographs obtained with the paralleling technique. Periapical status will be evaluated using the Periapical Index (PAI), scored from 1 (normal periapical structures) to 5 (severe periodontitis with exacerbating features). Teeth with PAI scores of 1 or 2 will be classified as healed, whereas teeth with PAI scores of 3, 4, or 5 will be classified as not healed. Changes in PAI scores will be evaluated over time and compared among treatment groups. Periapical healing will be assessed using the Periapical Index (PAI) before treatment, immediately after treatment, and at 6 and 12 months after treatment.
From baseline through 12 months after treatment (baseline, immediately post-treatment, month 6, and month 12)

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in Root Canal Microbial Composition
Time Frame: Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)

hanges in root canal microbial composition will be assessed using shotgun metagenomic sequencing of samples collected at three treatment stages. Taxonomic profiles will be evaluated before and after antimicrobial photodynamic therapy (aPDT) and compared among the standard needle irrigation (SNI), passive ultrasonic irrigation (PUI), and laser-activated irrigation (LAI) grou
Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)
Changes in Microbial Functional Gene Profiles
Time Frame: Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)

Changes in microbial functional gene profiles will be evaluated using shotgun metagenomic sequencing of root canal samples collected at S1, S2, and S3. Functional gene profiles will be compared across sampling stages and among the SNI, PUI, and LAI groups
Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)
Changes in Antimicrobial Resistance Gene Profiles
Time Frame: Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)

Antimicrobial resistance genes (ARGs) in root canal microbial samples will be characterized using shotgun metagenomic sequencing. Changes in ARG profiles will be evaluated across S1, S2, and S3 and compared among the SNI, PUI, and LAI groups.
Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)
Changes in Intracanal Inflammatory Cytokine Levels
Time Frame: Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)

Intracanal levels of IL-1β, IL-6, IL-8, IL-10, TNF-α, and IFN-γ will be measured using enzyme-linked immunosorbent assay (ELISA) in samples collected at S1, S2, and S3. Changes in cytokine levels will be evaluated across sampling stages and compared among the four study groups.
Day 1 (before treatment, after irrigation activation, and after antimicrobial photodynamic therapy)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Karadeniz Technical University

Investigators

  • Principal Investigator: Nihan Çelik Uzun, Assistant Professor, Karadeniz Technical University Faculty of Dentistry

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 1, 2026

Primary Completion (Estimated)

December 30, 2026

Study Completion (Estimated)

May 1, 2027

Study Registration Dates

First Submitted

October 13, 2026

First Submitted That Met QC Criteria

November 4, 2026

First Posted (Actual)

November 6, 2026

Study Record Updates

Last Update Posted (Actual)

November 6, 2026

Last Update Submitted That Met QC Criteria

November 4, 2026

Last Verified

October 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 25-AKD-307

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data (IPD) will not be shared with other researchers to protect participant privacy and confidentiality. Study findings will be reported in aggregate form in scientific publications

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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