Evaluation of the physical-chemical, mechanical and biocompatibility properties of different types of Portland cement, and their association to micro and nanoparticle radiopacifiers

Abstract

The mineral trioxide aggregate (MTA) has Portland cement (CP) in the basic composition. Some additives and vehicles may be added to the CP to improve consistency and clinical applicability. The aim of this study is to evaluate the physical-chemical, mechanical and biological properties of the white CP and modifications of white CP, besides the influence of the radiopacifier agents in the properties. Firstly, the white CP and modifications will be evaluated using different tests: setting time, flow ability, compressive strength, heavy metal levels and cellular viability using MTT assay. After that, two modifications of white CP will be selected to add different rardiopacifier agents - nano or micro particulate zirconium oxide, niobium oxide, zinc oxide and micro particulate bismuth oxide. MTA will be used as control. Heavy metals levels will be quantified by atomic absorption spectrophotometry. For compressive strength test (n=6), a mechanical machine will be used. The setting time (n=6) will be evaluated using standard Gilmore needles. In the radiopacity test (n=6),the specimens will be radiographed and compared with an aluminum scale. The surface of the samples (n=6) will be evaluated by scanning electron microscope. The flow ability (n=6) test will be performed according to ISO 6876 patterns varying the mensuration mode of the samples. To measure pH and calcium ion release (n=10), a digital pH meter will be used and the samples will be submitted to atomic absorption spectrophotometry, respectively. In the solubility test (n=6), the mass lost percentage by the material will be measured after immersion in water. The MTT and the apoptosis/necrosis assay will be performed to evaluate cell viability after expose them to the cements. The results will be submitted to ANOVA test and Tukey post-hoc test with 95% of significance. (AU)