Properties of one modified composite resin by TiO2 nanoparticles

Abstract

Purpose: The purpose of this study was to evaluate the compressive strength and color changes of one composite resin modified by TiO2 nanoparticles and their distribution by SEM. Methods and materials: TiO2 dispersed in SiO2 nanoparticles were synthesized by a polymeric precursor method using sol–gel technique and were incorporated at 1, 2, 5 and 10% w/w using FiltekTM Z350 composite resin (Z, color A2). One control and four experimental Groups were evaluated (Z-C, Z1, Z2, Z5 and Z10). For compressive strength (8mm× 4mm) (n=60) and color stability (n=50) (10mm× 2mm) the samples were light-cured for 40 s and for 240 s, respectively using LED LCU (Celalux, Voco). The distribution of the nanoparticles in the composite resin was observed by scanning electron microscopy (SEM). After storage in distilled water at 37 (±1 ◦C) for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5mmmin−1. Color parameters were analyzed in a Spectrophotometer Color-guide 45/0, PCB 6807 (BykGardnerGmbH, Gerestsried, Germany) to evaluate the color changes using CIE L*a*b* system after 24h and 90 days in artificial saliva. E* values greater than or equal to 3.3 were considered as a clinically unacceptable color change. Data for compressive strength and color changes were submitted to one-way analysis of variance (ANOVA) and Tukey’s test at 0.05 significance level. For SEM images, qualitative analysis was used. Results: The compressive strength mean values obtained were: Z: 228 (±11.31), Z1: 251,9 (±11.31); Z2: 199,5 (±10.47), Z5: 176 (±11.31) and Z10: 153,9 (±11.31). The 5 and 10% TiO2 nanoparticles showed a significant influence on compressive strength (p 3.3). The use of 1 or 2% TiO2 nanoparticles showed to be the best option to modify a composite resin.