fa تحقيقي Original Paper <div><strong>ABSTRACT</strong><br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Background and Objective: </strong>Anaerobic bacteria are the main cause of periodontitis. It has been shown that green tea and black tea have antibacterial effect. The aim of this study was to determine he antibacterial effect of Iranian green tea and black tea against <em>Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis </em>and<em> Prevotella intermedia.</em><br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Methods</strong>: Aqueous and methanolic extracts of Iranian green tea and black tea at concentrations ranging from 10 to 500 mg/ml were tested against standard strains of<em> A. actinomycetemcomitans&nbsp; </em>(ATCC 33384),<em> P. gingivalis </em>(ATCC 33227) and <em>P. intermedia</em> (ATCC 25671) using agar disk diffusion, broth microdilution and determination of minimum inhibitory concentration.<br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Results:</strong> <em>P. gingivalis, A. actinomycetemcomitans </em>and<em> P. intermedia </em>were sensitive to the methanolic extract of Iranian green tea at concentrations of 100-500 mg/ml, 10-500 mg/ml and 50-500mg/ml, respectively. <em>P. gingivalis, A. actinomycetemcomitans </em>and<em> P. intermedia </em>were sensitive to the methanolic extract of Iranian black tea at concentrations of 200-500 mg/ml, 20-500 mg/ml and 200-500 mg/ml, respectively.<a name="OLE_LINK69"></a><a name="OLE_LINK68"> In addition, </a><em>P. gingivalis</em><em>,</em> <em>A. actinomycetemcomitans </em>and <em>P. intermedia</em> were sensitive to the aquatic extract of Iranian green tea at concentrations of 200-500mg/ml, 100-500 mg/ml and 200-500 mg/ml<a name="OLE_LINK24"></a><a name="OLE_LINK23">, </a><a name="OLE_LINK11"></a><a name="OLE_LINK8">respectively</a>.<br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Conclusion: </strong><a name="OLE_LINK39"></a><a name="OLE_LINK38">The </a>aquatic and alcoholic extracts of Iranian green tea and black tea have antibacterial activity against <em>A. actinomycetemcomitans</em>, <em>P. intermedia</em> and <em>P. gingivalis</em>. Therefore, incorporation of Iranian black tea as an effective native herb could be beneficial for prevention of oral cavity diseases.<br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Keywords:<a name="OLE_LINK6"></a><a name="OLE_LINK5"></a><a name="OLE_LINK22"></a><a name="OLE_LINK21"></a> </strong>Tea, Green Tea, Antibacterial Agents, Anaerobic Bacteria.&nbsp;</div> Tea, Green Tea, Antibacterial Agents, Anaerobic Bacteria. 13 18 http://mlj.goums.ac.ir/browse.php?a_code=A-10-1-471&slc_lang=fa&sid=1 Mohammad Niakan 100319475328460013939 100319475328460013939 No Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran Noushin Jalayer Naderi jalayer@shahed.ac.ir 100319475328460013940 100319475328460013940 Yes Department of Oral and Maxillofacial Pathology, Faculty of Dentistry, Shahed University, Tehran, Iran Hadise Jamshidian 100319475328460013941 100319475328460013941 No Graduated student from Faculty of Dentistry, Shahed University, Tehran, Iran Fateme Jafariazad 100319475328460013942 100319475328460013942 No Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran