Avaliação do potencial de remineralização e da resistência de união de materiais restauradores bioativos em dentina afetada por cárie

Abstract

Minimally Invasive Dentistry encompasses a conservative approach to caries lesions and guides procedures for selective removal and handling of adhesive materials to restore the cavity. The present thesis consists of two chapters in which the first assesses the potential of experimental adhesives incorporated with calcium and phosphate associated with a bioactive resin to induce the formation of minerals in demineralized dentin. Three experimental adhesives were used: Exp. 1 (self-etch 1 step), Exp. 2 (self-etch 2 steps), Exp. 3 (etch and rinse 2 steps) and a control, Den-TASTIC (etch and rinse 2 steps) (Dentastic ™ UNO ™). Fourier transform infrared spectroscopy (ATR-FTIR) was used to assess dentin that was completely demineralized and infiltrated with ad-hesives (n=5) or with adhesives/restorative materials (n= 5) (Activa BioATIVE-RESTORATIVE or Clearfil Majesty Flow) after 0, 15, 30 and 45 days. Adhesive discs (n=5) were used to detect peaks of apatite formation at 0, 15, 30 and 60 days. The caries affected dentin (CAD) reminerali-zation process was evaluated using Microhardness (MH) and Confocal Microscopy (CM) after 0 and 3 months. Chapter 2 investigated the action of bioactive materials after chemical-mechanical removal of caries (Papacarie Duo GelR), through analysis of bonding strength (BS) and analysis in Scanning Electron Microscope (SEM). Human sound molars (n = 40) and with occlusal caries le-sions (n=40) were selected. A control adhesive (DenTASTIC) and three experimental ones were used: Exp. A (etch and rinse 3 steps), Exp. B (self-etch 2 steps), Exp. C (self-etch 1 step) and also two restorative materials (Activa or Clearfil). The restored teeth (n=5) were submitted to the BS test and analysis of the adhesive interfaces in SEM. The data were submitted to statistical analysis (p<0.05). The results of experiment 1 showed that partial dentin remineralization occurred after 7 days with Exp. 2/Activa, while Exp. 1 and Exp. 3 achieved this result after 2 weeks. All experi-mental adhesives showed a sign of bioactivity, but only Exp. 2 obtained peaks in apatite formation. The groups Exp. 3 and DenTASTIC obtained the highest MH value in depth of 50μm and 100μm for both restorative materials at baseline. After 3 months, for 50μm of depth, Activa/Exp. 1 sho-wed a higher MH value (p <0.01). There was no difference between groups in this analysis consi-dering 100μm of depth after 3 months (p> 0.05). CM showed remineralization in several stages for all groups, except for DenTASTIC. In sound dentin, Experiment 2 revealed only Exp.C was able to maintain and even improve BS when combined with Activa and Clearfil composites, res-pectively after 1 year. When applied in CAD, Exp. A, Exp. B and Exp. C obtained the best BS re-sults, regardless of the restorative materials (p<0.01). In conclusion, the experimental adhesives associated or not with a bioactive resin proved to be promising for the remineralization of demi-neralized dentin and were able to maintain or even improve BS to CAD, regardless of the adhesive strategy.