The main objective of this study is to evaluate the effect of treatment periodontal endothelium-dependent artery of the arm in patients with acute myocardial infarction with ST-segment elevation undergoing primary coronary intervention.

The present work sample will be composed by individuals who suffered from ST segment elevation myocardial infarction admitted to the Cardiologic Institute from Porto Alegre. Participants period of selection and evaluation extended from August 20th, 2012 to January 2015. The whole selection was performed by the responsible researcher, assessing periodontal condition of the individuals in the hospital bed. The participants will be accompanied during the hospital stay and outpatient basis, an expected average of six months.

Clinical Exam

Patients selected for the test group will receive periodontal examination in private offices. For the clinical exam, odontoscopy (Duflex®, Brasil) and Flórida 10mm periodontal catheters measured in millimeters (Newmar®, Brasil) will be employed. The clinical exam will be performed by an experienced periodontist (the same one who will perform the patients' treatment) and will include the evaluation of parameters related to the periodontal disease, which were noted by an assistant, in a standard form (Attachment A). All permanent teeth will be examined, except for the third molars. Periodontal variables will be evaluated in four sites per tooth (vestibular, distal, lingual and mesial), according to the following:

• Visible plaque index (VPI) - dental surfaces will be assessed by the naked eye after compressed air drying. Codes: 0 = absence of visible plaque, and 1 = presence of visible plaque (AINAMO and BAY, 1975).
• Catheterization Depth (CD) - distance from the gingival edge to the most apical portion able to be catheterized, in millimeters.
• Bleeding during Catheterization (BC): It will be registered the presence (score 1) or absence (score 0) of bleeding 30 seconds after measuring the catheterization depth
• Loss of Insertion (LI): It will be calculated through the distance between the amelocemental junction to the most apical portion of the periodontal pocket. This measurement will be performed in millimeters and always rounded down to the lowest mark.

Endothelial Function Exam Endothelial function assessment will be performed through endothelial dependent dilation of the brachial artery, observed through ultrasound with a linear 3-12 MHz transducer (EnVisor CHD, Philips, Bothell, WA, USA). Automated measurements of the vase diameter will be performed with a software from the equipment used in the procedure. The evaluations will be performed in the morning period, after an 8-hour fast, in controlled temperature (22°C). After ten minutes of rest, the images of the brachial artery will be recorded with a linear transducer continuously placed over the antecubital fossa for one minute (basal). The sphygmomanometer will be placed in the arm and insufflated to the edge of 50mmHG above systolic arterial pressure for five minutes, and the alteration in the diameter of the brachial artery 60 seconds after the cuff deflation will be compared to the basal diameter. The images of the vase in the end of the diastole (identified by the R wave in the ECG) will be digitalized and recorded in 3 second gaps during the whole procedure, being subsequently analyzed offline, using the software of the equipment used in the procedure.

After 10 minutes of rest, new measurements will be performed, measuring the endothelial dependent dilation through the administration of 25mg sublingual nytroglycerin. The flow measuring will be performed with a Doppler wave pulse at an angle of 70o. The increase in the blood flow after the arterial pressure liberation from the cuff will be expressed as reflex hyperemia (value for reflex hyperemia, divided by the baseline value for blood flow in the forearm). After one hundred and eighty days (6 months) a new Endothelial function assessment will be performed.

Periodontal Treatment Periodontal treatment will be performed by an expert in periodontics, in a private office, in the following treatment order. First, the case will be presented to the patients, providing information about periodontal diseases etiopathogeny, focusing on the importance of bacterial supragingival biofilm control for the treatment success. Afterwards, all the plaque retentive factors (dental calculus) will be removed in a single session. Decay lesions will be restored with provisional material; radicular debris will be extracted, and badly adapted restoration will be adjusted. Supragingival calculus will be removed with periodontal Gracey curettes (Newmar®, São Paulo, Brasil), followed by supragingival smoothing and polishing with rubber cup, prophylactic paste, dental floss and/or interdental brush. In the same session, participants will receive instructions on personalized oral hygiene, with multibristle brushes, toothpaste, dental floss and interdental brushes.

Fourteen days after the first appointment, under gingival radicular scraping and smoothing will be initiated (UGSS) with periodontal files and curettes (Newmar®, São Paulo, Brasil), under local anaesthesia, for a maximum period of four weeks. By the end of each UGSS appointment, patients will receive professional plaque removal and oral hygiene reinforcement, according to individual needs, for motivation and effective behavior change regarding to oral health care.

After periodontal treatment, patients from the test group will receive clinical reassessment after ninety days for hygiene reinforcement and professional teeth plaque removal. After one hundred and eighty days (6 months) a new complete periodontal exam will be performed.

Sample Calculation Minimum sample size will be calculated in 88 patients to detect a flow mediated dilation difference of 1% between the two study groups, with an average standard deviation of 1,67%, for a p<0,05 and statistical power of 90%.

Randomization Patients will be selected and invited to participate during hospital admission. Randomization will be performed two weeks after hospital discharge. Patients will be randomly distributed through the use of a computer generated table (randomization.com), to receive periodontal treatment (test group) or to participate in the control group, which will not receive any clinical intervention during the experiment period, but will be referred to periodontal treatment after the experimental period.

Blinding Endothelial disfunction evaluation will be performed by a professional that won't be aware of group allocation of each patient (test or control), either in the begging or end of the study.

Statistical Analysis Data will be presented as means and standard deviation, with confidence intervals of 95%, and relative and absolute frequencies. All the analysis will be based on the intention to treat principle. t Student test for impaired samples will be used to compare periodontal exam values before and after treatment. General estimative equations method, followed by multiple comparisons with bonferroni correction will be used to compare the DMF percentage intra and intergroup (intervention x control), and the covariance analysis will be used to compare the DMF variation (before and after treatment delta) between the control and intervention group, adjusted to the initial values. All data will be analyzed by SPSS software, version 22, and the significance value considered in the analysis of 0,05.

Inclusion Criteria:

• patients admitted to our institution with a diagnosis of AMI (ST segment elevation> 0.1mV)
• older than 30 years
• with more than 8 teeth in the mouth
• with advanced periodontal disease

Exclusion Criteria:

• acute or chronical infection
• impossibility of attending the following interviews and/or the periodontal treatment
• refusing to signing the consent form
• individuals with substance abuse
• anticonvulsants and immunosuppressant drugs users
• pregnant and \ or lactating women.