Skip to main content
OpenTrials
Completed

NCT Number: NCT07683520

Adjunctive Oral Probiotics in Endodontic Retreatment: Effects on Postoperative Pain and RANKL/OPG Levels

This study aimed to evaluate the effect of oral administration of probiotics as an adjunctive treatment to local intracanal medicaments, namely propolis and calcium hydroxide or empty canal, on the levels of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG), as well as on postoperative pain following root canal retreatment of teeth with chronic apical periodontitis

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Chronic Apical Periodontitis Neurologic Manifestations Pain Pain, Postoperative Pathologic Processes Pathological Conditions, Signs and Symptoms Postoperative Complications Signs and Symptoms

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Faculty of Dentistry, Ain Shams University

Cairo, Cairo Governorate, 11566, Egypt

About this study

Post-treatment chronic apical periodontitis is an inflammatory condition caused by persistent microbial infection within the root canal system, characterized by progressive periapical bone destruction mediated by host immune-inflammatory mechanisms. Root canal retreatment remains the treatment of choice for failed endodontic cases; however, postoperative pain and incomplete resolution of inflammatory mediators remain common concerns. Clinical evidence demonstrates that postoperative pain following endodontic retreatment is influenced by microbial persistence, host inflammatory response, and intracanal medication protocols.

The RANK/RANKL/OPG axis is a key regulator of osteoclastic activity and periapical bone resorption. Elevated RANKL levels and altered RANKL/OPG ratio are associated with active periapical bone destruction. Modulation of this pathway may improve healing outcomes. Recent studies suggest that probiotics can regulate immune response, reduce inflammatory cytokines, and decrease RANKL expression.

This randomized clinical trial includes patients diagnosed with previously root-filled teeth presenting with chronic apical periodontitis indicated for non-surgical retreatment.

Standardized retreatment procedures are performed under aseptic conditions. Periapical exudate samples collected for biochemical analysis of RANKL and OPG levels at predetermined time points. Postoperative pain is assessed to investigate whether systemic probiotic administration can act as a host-modulating adjunct in endodontic retreatment and improve both symptomatic and biological healing outcomes.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Previously treated failed single rooted teeth with chronic apical periodontitis.
  • No use of antibiotic three months before treatment.
  • Patients are free of any systemic disease.
  • Positive patient acceptance for participation

Exclusion criteria

  • Teeth that are badly broken down with difficult isolation.
  • Signs of acute infection, root fracture, root surface caries, swellings or ankylosis
  • Periodontally affected teeth with pockets deeper than 4mm.
  • Pregnant or lactating woman.
  • Patients who needs any prophylactic antibiotic.
  • Patients with allergy to pollen.

Treatment and study plan

Linex Adult®

Dietary Supplement

Linex Adult® is an oral probiotic formulation containing Lactobacillus acidophilus, Bifidobacterium animalis, It is administered as one capsule once daily for 21 days.

Other names: Lactobacillus acidophilus, Bifidobacterium animalis

Ca(OH)2 as intracanal medicament

Drug

Intracanal medication kept for 21 days

Other names: Metapaste

Placebo

Other

Placebo capsule for 21 days

Other names: Matching placebo

propolis intracanal medication

Drug

Intracanal medication kept for 21 days

Other names: Intracanal propolis medicament

Empty canal

Other

Empty canal for 21 days

Other names: No intracanal medicament

Primary outcomes

  1. The effect on RANKL and OPG levels in teeth with chronic apical periodontitis.

    Time frame: (S1) measured in the first visit Immediately post-instrumentation and before ICM placement or oral supplement administration. (S2) After 21 days, immediately after removal of ICM and before obturation.

    Level of RANKL and OPG measured with periapical samples (S1) and (S2) and analysed using ELISA test

Secondary outcomes

  1. The effect on postoperative pain.

    Time frame: Inter-appointment pain: baseline (start of the first visit), 4, 12, 24, 48, and 72 hours, and Week 1 and Week 2 after the first visit. Post-obturation pain: baseline (start of the second visit), 4, 12, 24, 48, and 72 hours after obturation.

    Pain level measured using the Numeric Rating Scale (NRS), ranging from 0 (no pain) to 10 (worst possible pain), to evaluate inter-appointment pain between the first and second retreatment visits and post-obturation pain after the second retreatment visit and root canal obturation.

Sponsors and collaborators

Lead sponsor

Ain Shams University

Other

Registry information

Official study title

The Effect of Systemic Administration of Probiotics and Intra-Canal Medications on Level of Nuclear Factor Kappa B Ligand, Osteoprotegerin and Postoperative Pain in Patients With Chronic Apical Periodontitis: (Randomized Controlled Clinical Trial)

Acronym: RANKL/OPG

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jul 6, 2026
Registry last updated
Jul 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.