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Evaluation of some physico-chemical and biological properties of a new root canal sealer based on AH 26

Grant number: 11/11560-1
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): December 01, 2011
Effective date (End): January 31, 2013
Field of knowledge:Health Sciences - Dentistry - Endodontics
Principal researcher:Ivaldo Gomes de Moraes
Grantee:Fernando Accorsi Orosco
Home Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

This research aims to formulate a basic cement for root canal filling, the epoxy resin, as powder / liquid, based on cement AH26, calcium hydroxide in its composition, using in its composition, substances that not lead to deterioration in its color and hence the dental crown. For that, formulated three basic compositions containing calcium tungstate, calcium hydroxide and hexamethylenetetramine in different proportions and subjected to the following tests: setting time, solubility, radiopacity, flow, pH measurements, release of calcium ions and color change. Chosen the optimal formulation, it will be tested for antimicrobial activity, marginal seal, through the fluid transport system, and tissue reaction after implantation in subcutaneous tissue of rats. The method used to evaluate the antimicrobial action is the dissemination of the agent (cement) in a radial manner in agar culture. The sensitivity of the microorganisms will be evaluated by the presence or absence of inhibition halos, which will be measured using a millimeter ruler and very light. The bacteria used for the evaluation will be Sthaphylococus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Klebisiella sp. With respect to the culture medium will be used "Brain Heart Infusion - Agar - Merck. The reading and measurement of inhibition halos are performed after 24, 48 and 168 hours. The leakage will be assessed by the fluid transport system, using twenty-six teeth that have the root canals were prepared biomechanically and obturated. Measurements will be made with an automatic device (FLODEC System, Marco Engineering, Geneva, Switzerland). This unit is equipped with detectors capable of detecting electric displacement of the air bubble inside the glass capillary. This information is transmitted to a computer attached to the device, which through a specific program automatically converts the shift to data flow. To evaluate the tissue response will be used 24 Wistar rats (rattus norvegicus) were divided into three groups with eight animals each according to the experimental periods, which will be 15, 30 and 60 days. Each animal received four implants, two with experimental cement and two with Sealer 26; gutta-percha used for sealing one end of the polyethylene tubes serve as control. After the experimental periods, the animals will be killed and the specimens are removed and prepared for analysis by optical microscopy and morphometric so descriptive, considering the following morphological criteria: the volume density of the fibers, fibroblasts, inflammatory cells, vessels and other components present in the reaction produced by the cement. Data from all tests except the test that will examine the antimicrobial action, will be tested for normality and, once the presence or absence of same, will be determined by parametric tests (ANOVA and Tukey's test) or non- parametric (Kuskall-Wallis and Miller). Will be adopted the significance level of 5%. In the analysis of antimicrobial action, will be given only the means of inhibition halos formed in periods of 24, 48 and 168 hours. Key-words: Physical and chemical properties. Biological property. Root canal sealers. Microleakage.