Effect of antimicrobial polymer incorporation on Knoop hardness, crosslinking density and depth of cure of experimental resin composites

• Grant number: 20/00336-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2020
• End date: June 30, 2021
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Roberta Caroline Bruschi Alonso
• Grantee: Victor Martins Stabile
• Host Institution: Pró-Reitoria Acadêmica. Universidade de Mogi das Cruzes (UMC). Campus da Sede Mogi das Cruzes. Mogi das Cruzes , SP, Brazil

Abstract

The aim of this study is to evaluate the effect of incorporation of a polymer with antimicrobial properties on Knoop hardness, crosslinking density and depth of cure of experimental resin composites, in order to establish formulations with more favorable characteristics to dental restoration. Therefore, 4 experimental composites based on UDMA / TEGDMA will be prepared with different concentrations of PMTA 1 antimicrobial polymer (0%, 1%, 3% and 10%). For the analysis of Knoop Hardness and Cross-Link Density, circular specimens (5 mm diameter x 2 mm thickness) will be made from prefabricated silicone mold (n = 10), stored at 37°C for 24 hours and submitted to finishing and polishing procedures. For hardness evaluation, a microhardness tester (model HMV 2000, Shimadzu, Tokyo, Japan) with 50 g load applied for 15 seconds will be used. The crosslink density will be indirectly evaluated by the evaluation of harness before and after immersion of the specimens in etanol for 24 hours, once polymers with lower crosslinking density shows higher hardness decreasing after exposure to organic solvents. For depth of cure analysis, 5 specimens (3 mm diameter x 5 mm deep) will be made, stored at 37°C for 24 hours, and submitted to finishing and polishing. Depth of cure will also be evaluated using the HMV 2000 microhardness tester (Shimadzu, Tokyo, Japan) with 50g load, for 15s. Hardness will be evaluated at subsurface and at 1 mm, 2 mm, 3 mm and 4 mm depth. Three indentation will be evaluated at each depth, making a total of 15 measurements in each specimen. The data will be submitted to appropriate statistical analysis. Initially, data will be evaluated for normality by the Kolmogorov-Smirnov test, and presenting normal distribution, will be submitted to ANOVA and the means compared by Tukey's test, with a significance level of 5%. (AU)