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
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
72
Linex Adult® is an oral probiotic formulation containing Lactobacillus acidophilus, Bifidobacterium animalis, It is administered as one capsule once daily for 21 days.
Intracanal medication kept for 21 days
Placebo capsule for 21 days
Faculty of Dentistry, Ain Shams University
Cairo, Cairo Governorate, Egypt
The effect on RANKL and OPG levels in teeth with chronic apical periodontitis.
Level of RANKL and OPG measured with periapical samples (S1) and (S2) and analysed using ELISA test
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.
The effect on postoperative pain.
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.
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.
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Intracanal medication kept for 21 days
Empty canal for 21 days