Apical periodontitis (AP) is caused by an inflammation of the periradicular tissues after bacterial contamination of the root canal system by pulp exposure by caries, trauma or tooth wear. Smoking has been associated with an increase in the prevalence of apical periodontitis and failures in endodontic treatments. Omega-3 fatty acids (É-3 PUFAs) are recommended as an adjuvant therapy to conventional endodontic treatment, due to their anti-inflammatory properties. The aim of the present study is to investigate the influence of systemic Omega-3 supplementation on the association between smoking and induced apical periodontitis in rats on the bone resorption process. Sixty-four animals will be divided into 8 groups (n=8): C (control, rats without PA and without cigarette exposure; PA (rats with induced apical periodontitis); F (rats exposed to cigarette smoke); FPA (rats with induced apical periodontitis and exposed to cigarette smoke); PA+O (rats with induced apical periodontitis supplemented with Omega-3); F+O (rats exposed to cigarette smoke supplemented with Omega-3); FPA+O (rats with induced apical periodontitis exposed to cigarette smoke supplemented with Omega-3), C+O (rats without PA without cigarette exposure supplemented with Omega-3) For inhalation of cigarette smoke, animals (F, FPA, F+ O, FPA+O) will be placed in a smoking chamber for eight minutes, three times a day for 20 days before BP induction. The same procedure will be performed in non-smoking animals (C, PA, C+O, PA+O ), but without the presence of cigarette smoke. On the 5th day of inhalation, the animals in the groups (C+O, PA+O, F+O, FPA+O) will start prophylactic supplementation. a with Omega-3 for 15 days and the control animals (C, PA, F, FPA) will receive distilled water for the same period. On the 20th day, the animals will have the pulp of the first lower right molars exposed to the oral environment for the induction of the periapical lesion (PA), and will remain open for a period of 30 days. During this period, the animals will continue inhaling cigarette smoke associated with therapeutic supplementation for another 30 days, totaling 50 days of smoke inhalation protocol and 45 days of Omega-3 supplementation. At the time of euthanasia, the mandibles will be removed, fixed in 4% formaldehyde for 48 hours, washed in running water for 12 hours and placed in 70º Alcohol for scanning in Micro-CT, after which the pieces will be processed for histopathological and histometry by staining in Hematoxylin and Eosin (HE). The data obtained will be tabulated and submitted to statistical analysis with a significance level of 5%.
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