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Preliminary study of addition of bioactive ceramic particles in the composition of experimental adhesives

Grant number: 15/17917-0
Support Opportunities:Scholarships abroad - Research
Effective date (Start): August 01, 2016
Effective date (End): July 31, 2017
Field of knowledge:Health Sciences - Dentistry - Dental Materials
Principal Investigator:Fernanda de Carvalho Panzeri Pires de Souza
Grantee:Fernanda de Carvalho Panzeri Pires de Souza
Host Investigator: Jean-Francois Roulet
Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
Research place: University of Florida, Gainesville (UF), United States  


Bioactive materials have been used because of their ability to actively interact with dental or other mineralized tissues, leading to deposition of calcium and phosphate in the presence of body fluids or saliva. Although the adhesive systems have evolved significantly, the total etch of the dentin still shows the best results in in vitro and in vivo tests. However, the presence of unprotected collagen is considered one of the major drawbacks of these systems. Recently, a bioactive ceramic glass has been developed (Biosilicate) with proved antimicrobial properties, ability to induce remineralization and dentin tubules occlusion. The objective of this study is to evaluate the influence of the addition of Biosilicate particles, in different concentrations in the composition of experimental adhesive systems, and to compare their performance to commercial adhesives, of the same category. The hypothesis to be tested will be that the bond strength and the characteristics of the hybrid layer will be improved with Biosilicate addition, regardless of concentration. Percentages of 0% (control), 2%, 5% and 10% (by weight) microparticles Biosilicate® (1 uM) will be incorporated on 2 types of experimental adhesives: Experimental 1 (total etch, 2 steps) and Experimental 2 (self-etching, 2 steps). Initially, conversion degree and wettability will be evaluated. From the analysis of these results, two concentrations of Biosilicate, which previously showed the best results of the studied properties, will be selected. Then, bond strength (BS) of composites will be evaluated in 40 extracted healthy human molars, which will be sectioned into quarters (mesiobuccal, mesiolingual, distobuccal, distolingual). After flattening the dentine with silicon carbide sandpaper, the dental quarters will receive the adhesive protocols with different concentrations of Biosilicate, including 0% (control), totalizing 10 quarters per group. The teeth will be restored with 5 mm resin composite, according to incremental technique. Then, teeth will be sectioned vertically in stick format (1mm2) then submitted to microtensile test in a testing machine (EMIC) at a speed of 0.5 mm/min. After fractures, sticks will be qualitatively analyzed in a digital microscope (Keyence) and scanning electron microscopy (SEM, JSM-5600LV, JEOL) The fracture pattern will be classified as adhesive, cohesive and mixed. The analysis of the adhesive interface will be evaluated in 8 healthy human teeth, treated and filled in the same way as described for BS test. Each quarter will be sectioned into 3 slices in the mesial-distal direction, then processed and analyzed by SEM. Morphological and chemical characteristics will be analyzed (SEM, EDX, TEM and Raman). Quantitative data will be statistically analyzed according to normal distribution of the data. (AU)

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