Does Calcium Hydroxide Reduce Endotoxins in Infected Root Canals? Systematic Review and Meta-analysis

The purpose of this study was to evaluate the potential of endotoxin reduction by comparing the number of lipopolysaccharides (LPSs) before and after the use of calcium hydroxide (Ca[OH]2) as intracanal medication (ICM). Searches were performed up to June 2020. Clinical and experimental studies comparing the amount of LPSs before and after the use of Ca(OH)2 as ICM in infected root canals were included. Risks of bias assessment and data extraction were performed. Meta-analysis was conducted by subgrouping according to Ca(OH)2, the presence of an antimicrobial substance (AS), irrigant solution during chemomechanical preparation (CMP), and the incidence of LPS reduction. The certainty of evidence was determined by the Grading of Recommendations Assessment, Development and Evaluation approach. Nine studies were included in the qualitative synthesis and 7 in the meta-analysis. Three articles had low risk of bias (RB), 1 had moderate RB, 2 had high RB, and 3 “some concerns.” Overall, Ca(OH)2, with or without AS, reduced mean LPSs before CMP (standardized mean difference [SMD] = −1.087 [confidence interval {CI}, −1.453 to −0.721], P < .001, I2 = 58.7%) and after CMP (SMD = −0.919 [CI, −1.156 to −0.682], P < .001, I2 = 24.7%). Considering the irrigant solutions, the overall results showed a reduction before (SMD = −1.053 [CI, −1.311 to −0.795], P < .001, I2 = 58.7%) and after CMP (SMD = −0.938 [CI, −1.147 to −0.729], P < .001, I2 = 24,6%). Analyses presented very low certainty of evidence. The incidence of LPS reduction was 98.9% and 61.7% for Ca(OH)2 with and without AS, respectively. Ca(OH)2 reduces endotoxin levels when used as ICM but is unable to eliminate LPSs completely independent of the irrigating solution used with very low certainty of evidence.