Effect of the photoactivation method and hydrolitic degradation on the Knoop Hardness, surface roughness and flexural properties of a nanohybrid dental composite

• Grant number: 11/22460-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2012
• End date: December 31, 2012
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Regina Maria Puppin Rontani
• Grantee: Janine Belloti
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

The aim of this study was to evaluate the influence of the photoactivation method and hydrolytic degradation on the Knoop Hardness, surface roughness, and flexural properties of a nanohybrid composite. Specimens will be made from a nanohybrid composite (Empress Direct, Ivoclar Vivadent) and photocured in accordance with the following photoactivation methods: continuous light (CL), soft-start (SS), and pulse-delay (PD) (the energy dose standardized at 40J/cm2). Then, mechanical properties will be evaluated at 24 hs, 3, and 6 months of water storage. For the Knoop hardness and surface roughness test, composite specimens will be made (5 mm in diameter x 2 mm in thickness) and photocured by LED (1000 mW/cm2) for the 20s. Hardness will be measured in a microdurometer tester (HMV-2000, Shimadzu) and the hardness values will be the mean of 5 indentations on the top and bottom surfaces. Superficial roughness will be measured with a rugosimeter and the roughness value will be the mean of 3 roughness readings. For the flexural strength and modulus, bar-shaped specimens (7 mm length x 1 mm thick x 2 mm width) will be submitted to a three-point bending test in a universal testing machine. Then, data will be submitted to one-way repeated measures ANOVA and Tukey test (±=0.05).(AU)