The chemical solutions used to assist the endodontic instruments in the cleanse of the root canal system cause changes in the physicochemical properties of dentin, which may affect the adhesion of sealers and microorganisms. The objective of this study is to evaluate the effects of different irrigation regimes in physico-chemical properties of dentin and the consequences of these changes in adherence of microorganisms and AH Plus sealer. Fragments of root dentine will be subjected to photoacoustic Fourier-transform infrared spectroscopy (PA-FTIRS) for determining the changes in the components of the dentin and the time required for sodium hypochlorite (NaOCl) to deproteinate the collagen matrix exposed by chelating agents. The same specimens will be submitted to the scanning electron microscopy (SEM) for surface characterization and to the energy-dispersive X-ray spectroscopy (EDS) for determination of dentin components. New specimens will be prepared to assess changes in roughness by profilometer. Following, the dentin wettability will be determined by sessile drop technique and finally, these specimens will be subjected to the adhesion test of Enterococcus faecalis and Candida albicans in confocal laser scanning microscopy (CLSM). Lastly, transverse disks of roots will be obtained to evaluate the adhesion of AH Plus sealer by a push-out test and the sealer penetration in dentinal tubules by SEM and CLSM. After the adhesion test, the discs will be sectioned to determine the type of sealer fracture in a stereomicroscope. After each analysis, statistical tests will be conducted and then multiple linear regression analysis will be applied to correlate changes and dentin surface characteristics with sealer and microorganisms adhesion.
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