7 Clinical and Histological Evaluation of Barberry Gel on Periodontal Inflammation Abbas Makarem, Amir Moeintaghavi, Hossein Orafaei, Mahboube Shabzendedar and Iman Parissay Mashhad University of Medical Sciences, Mashhad, Iran 1. Introduction Gingivitis and periodontitis are the most common inflammatory oral diseases (Newman et.al./2006). Gingivitis is the most common periodontal disease in children and adolescents (Mc Donald et.al./2011). Periodontitis is an inflammation of the tissues and ligaments that support teeth (that could lead to loosening and subsequent tooth loss) due to infections with microorganisms participate in dental plaque (Newman et.al./2006). Gingivitis involves primarily inflammation of gingival tissues (Newman et.al./2006). Clinically, it appears as an inflammation of the gingival tissues next to the tooth. Microscopically, it is characterized by the presence of an inflammatory exudates and edema, destruction of collagenous gingival fibers, and ulceration and proliferation of the epithelium facing the tooth and attaching the gingival to it (Mc Donald et.al./2011). Various studies have shown increased, world-wide gingivitis prevalence rates, especially in developing countries. For example, only 11.3% of 15-19 year-old Iranians had healthy periodontal tissues, 12% had bleeding during probing, 46% presented with gingival calculus, 30.4% had shallow dental pockets and 0.3% had deep pockets in their jaw sextants (Kazemnejad et. al./ 2008, Khordimood & Makarem /2002). Despite of the changing concepts on the etiology that considered plaque as an etiologic factor for periodontal diseases, an oral self care (for plaque control) is still an essential step in the prevention and treatment of gingivitis (Marsh &Bradshaw1993.Makarem et.al.2006). Bacterial plaque is composed of soft bacterial deposits that adhere firmly to the teeth and form a complex, metabolically interconnected, highly organized bacterial system consisting of dense masses of microorganisms embedded in an inter microbial matrix. In sufficient concentration, this microbial matrix can disturb the host-parasite relationship and cause dental caries and periodontal diseases (Mc Donald et.al./2011). Since most individuals, especially children and adolescents seem to have difficulty in achieving perfect plaque control by mechanical means, investigations have been directed towards the dentifrices (Pooreslami & Makarem /2002). 2. Plaque control Chemical plaque control and prevention has been focused on various periodontal preventive strategies since 1980 and include the use of antibiotics (e.g., metronidazole),