Abstract
The aim of this study is to 1) evaluate the ion release of an experimental composite containing dicalcium phosphate dihidrate (DCPD) particles, and of a commercial composite containing particles capable of releasing phosphate, fluoride, calcium, aluminum, boron, sodium, silicon, strontium and zinc ions (Beautiful Bulk Restorative Universal®, Shofu) compared to a control composite (Z250®, 3M ESPE) in vitro 2) evaluate, through a microcosm biofilm model, the ability of the experimental and commercial composite to inhibit enamel demineralization around restorations compared to the control composite. Material and methods: for study 1, 45 blocks of bovine teeth will be prepared with a cavity measuring 6 x 6 mm. The specimens will be randomly distributed in 3 groups according to surface hardness values at baseline (n = 15) and restored with one of the experimental compounds: experimental composite resin containing dicalcium phosphate dihidrate (DCPD), commercial composite containing particles capable of releasing phosphate, fluoride, calcium, aluminum, boron, sodium, silicon, strontium and zinc ions (Beautiful Bulk Restorative Universal®, Shofu) and control composite (Z250®, 3M ESPE). These blocks will be subjected to pH-cycles for 8 days, being kept for 20 hours in remineralizing solution and 4 hours demineralizing solution. The release of calcium and phosphate ions from DCPD materials and Giomer technology will be evaluated by inductively activated plasma optical emission spectrometry and the fluoride release, by the direct method. For study 2, 144 enamel samples restored with one of the compounds previously mentioned will be subjected to the formation of a microcosm biofilm. The microcosm biofilm will be induced for 5 days, using McBain's saliva with 0.2% sucrose, at 37 ° C and 5% CO2. The response variables related to the biofilm analysis will be: bacterial viability and extracellular polysaccharide biovolume by fluorescence, using kits for confocal microscopy; CFU count for total microorganisms, total Streptococci, Mutans Streptococcus and total Lactobacilli; and quantification of lactic acid production using the lactic dehydrogenase kit and microplate reader. Surface enamel microhardness around the restorations will be evaluated at baseline and after the induction of the microcosm biofilm. Subsequently, the transverse microhardness will also be evaluated and the mineral content will be assessed using transverse microradiography (TMR). Once the results are homoscedastic, an analysis of variance (ANOVA) will be applied, complemented by the Tukey test for contrast between the media, with a significance level of 5%. (AU)