en Oral medicine Oral medicine Original article Original article <pre data-placeholder="Translation" dir="rtl" id="tw-target-text"> </pre> <strong>Introduction:&nbsp;</strong>The antibacterial effects of coconut products have been extensively studied in the recent years. Due to the high prevalence of periodontal disease and the role of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in periodontitis, antimicrobial agents can be effective in controlling this condition. This study aimed to evaluate and compare the antimicrobial effects of coconut water and coconut oil on A. actinomycetemcomitans.<br> <strong>Materials and Methods:</strong>&nbsp;Coconut water was extracted by cracking a coconut and coconut oil was extracted by an oil-pressing machine by the cold pressing method at -50 ̊C. The disc diffusion test was carried out on 4 plates containing coconut oil, coconut water, positive control, and negative control to measure the diameter of growth inhibition zone. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. All tests were repeated 3 times.<br> <strong>Result:</strong>&nbsp;Coconut oil in 100% concentration showed no antibacterial effect on A. actinomycetemcomitans in the disc diffusion test. Thus, the MBC and MIC were not determined for coconut oil. Coconut water demonstrated a bactericidal effect with 11, 9, and 0 mm growth inhibition zone diameter on 3 consecutive repetitions. According to independent t-test, a significant difference existed between the diameter of growth inhibition zone caused by coconut oil and positive control (P= 0.001).<br> <strong>Conclusion:</strong>&nbsp;Coconut oil showed no antibacterial effect on A. actinomycetemcomitans, and the antibacterial effect of coconut water on A. actinomycetemcomitans was very weak. Aggregatibacter actinomycetemcomitans, Coconut Oil, Anti-Bacterial Agents 40 46 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-839-1&slc_lang=en&sid=1 Maryam Baharvand m.baharvand@gmail.com 10031947532846008780 10031947532846008780 No Oral Medicine Dept. School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mehdi Shokri mehdyshokri@gmail.com 10031947532846008781 10031947532846008781 No Department of Dental Biomaterials, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Sarah Hassani sara71.hassani@gmail.com 10031947532846008782 10031947532846008782 No General Dental Practitioner, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Homa Mirzaei homamirzaei87@gmail.com 10031947532846008783 10031947532846008783 Yes Postgraduate student, Department of Oral Medicine, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mina Mahdian mahdianmina@gmail.com 10031947532846008784 10031947532846008784 No Department of prosthodontics and Digital Technology, Stony Brook University, School of Dental Medicine, Stony Brook, NY, USA.