Objectives: The aim of this study was to evaluate the antibacterial and cleaning abilities of different antibiotic solutions, in combination with detergent and citric acid, and compare them to that of MTAD. Materials and methods: Seventy recently extracted permanent human maxillary molars were used in thestudy which were Prepared using protaper system up to F5 and contaminated with E.faecalis then dividedinto three groups which were treated as follow:Group 1: Subgroup 1 (Unasyn): teeth were irrigated with 2 ml of the cleaning solutions {citric acid (4.25%)and tween 80 (0.5%)} followed by irrigation with 5 ml of Unasyn .Group 1: Subgroup 2 (Cefobid): teeth were irrigated with 2 ml of the cleaning solutions {citric acid (4.25%)and tween 80 (0.5%)} followed by irrigation with 5 ml of Cefobid .Group 1: Subgroup 3 (Zithromax): teeth were irrigated with 2 ml of the cleaning solutions {citric acid (4.25%)and tween 80 (0.5%)} followed by irrigation with 5 ml of Zithromax .Group 2: Subgroup 1 (Unasyn+): teeth were irrigated with Cefobid after mixing it with tween 80 (0.5%) andcitric acid (4.25%) before irrigation.Group 2: Subgroup 2 (Cefobid+): teeth were irrigated with Cefobid after mixing it with tween 80 (0.5%) andcitric acid (4.25%) before irrigation.Group 2: Subgroup 3 (Zithromax+): teeth were irrigated with Zithromax after mixing it with tween 80 (0.5%)and citric acid (4.25%) before irrigation.Group 3: 10 teeth were irrigated with BioPure MTAD, according to the manufacturer’s instructions.A classical bacterial counting technique was used for each group for the recovery of viable E. faecalis onMueller-Hinton agar plates. The purity of the positive cultures was confirmed by Gram staining, by colonymorphology on BHI agar + blood. The mean value of CFU for the plates of each group was then calculated.Part IIScanning electron microscope examination:Two specimens from each group were taken to examine the condition of dentinal walls and debris. Eachspecimen was cut vertically into two equal parts. Each specimen was mounted in aluminum stubs and sputtercoatedwith gold (EMITECH K550X sputter coater, England). Photographs were taken at the coronal, middleand apical levels of the roots and findings were then recorded.Results: The results obtained from this study indicated that there was a statistically significant reduction inthe mean values of the bacterial count after the application of the alocated treatment for each group with thebest results obtained with MTAD, Unasyn, Zithromax, Cefobid, Zithromax+, Unasyn+ and finally comesCefobid+ The average percent scores for debris and smear layer was the least for MTAD group followed byZithromax group, followed by Cefobid group, then Unasyn group, after treatment of the canals with detergentand citric acid. Followed by Zithromax, Cefobid and Unasyn respectively after mixing them with detergentand citric acid.Conclusion: All antibiotics showed a statistically significant bacterial count reduction.•Pretreatment of the canals with detergent and citric acid enhanced the antibacterial and cleaning effects ofdifferent antibiotics.•BioPure MTAD possesses a significant antibacterial effect against E. faecalis.•BioPure MTAD showed a great effect on smear layer removal.•Irrigation with Unasyn after cleaning canals with detergent and citric acid achieved significant bacterial countreduction close to that of MTAD.•Irrigation with Zithromax after cleaning canals with detergent and citric acid showed the best resultsconcerning smear layer removal and dentinal debris elimination close to that of MTAD.