Aim:The purpose of this study was to compare the antibacterial effects of Allium sativum (garlic extract), calcium hydroxide (Ca [OH] 2 ) and their combination as intracanal medicaments in infected mature anterior teeth using real-time PCR.Methodology: This prospective double-blind, controlled, parallel, superiority, randomized clinical trial was carried out on 66 permanent, necrotic incisors associated with asymptomatic apical periodontitis in 66 male patients. Patients were randomly divided into three groups (n = 22) according to the intracanal medications used.After access preparation, four microbiological samples (S) were taken using sterile absorbent paper points as follows: S1: before canal instrumentation and S2: after cleaning and shaping. The third sample (S3) and fourth sample (S4) were taken after the placement of the tested intracanal medications into their corresponding canals for 7 and 14 days, respectively. Total DNA was extracted from microbiological samples and relative quantitative real-time PCRs were done to quantify the relative gene expression fold change (FC) for Enterococcus faecalis and Streptococcus species. At significance level p ≤ .05, the data were statistically analysed in SPSS software using Kruskal-Wallis and Freidman's tests, followed by Dunn-Bonferroni post hoc test for pairwise comparisons.Results: Both bacterial mean FC decreased significantly after mechanical instrumentation (S1 to S2) in all groups. However, no statistically significant differences were found after intracanal medicament placement (from S2 to S3 and from S3 to S4) except in the garlic group. Garlic significantly reduced Enterococcus faecalis FC in S3 and S4 when compared to Ca (OH) 2 and Ca (OH) 2 + garlic combination. However, garlic and Ca (OH) 2 reduced Streptococcus bacteria in S3 similarly. Whilst in S4, garlic showed significantly more reduction than Ca (OH) 2 . The combination of Ca (OH) 2 with garlic extract showed the least significant bacterial reduction.
Conclusion:Within the study limitations, garlic intracanal medicament has a comparable anti-Streptococcus efficiency to Ca (OH) 2 , whilst it is more effective against Enterococcus faecalis species. When Ca (OH) 2 and garlic are combined, their
