Influences of TiO2 and SiO2 nanofillers on the hardness and surface roughness of maxillofacial silicone elastomers after two years of outdoor tropical weathering: An in vitro study

The properties of maxillofacial silicone elastomers (MFSE) are far from ideal and still require reinforcement. The incorporation of nanofillers (NFs) at high levels still requires further investigation. This study evaluated the influence of different percentages (3 and 10% w/w) of titanium dioxide (TiO2) and silica (SiO2) NFs on the roughness and hardness of A-2000 silicone elastomer after two years of natural weathering. A total of 80 accepted specimens were divided into two groups: weathered and non-weathered. Each group was equally subdivided into 5 subgroups: non-filled, filled with 3% SiO2, 10% SiO2, 3% TiO2, and 10% TiO2. Surface roughness was quantitatively measured using a profilometer and qualitatively using a Scanning Electron Microscope (SEM). The hardness was measured using a digital Shore-A durometer. The chemical interaction between NFs and elastomers was examined using Fourier Transform Infrared (FTIR) spectroscopy. The data were exported to SPSS, and the analysis was done using 1-way ANOVA and an independent t-test. Adding 10% SiO2 and TiO2 NFs significantly decreased the surface roughness of A-2000 MFSE, with no significance among all concentrations after 2-year natural weathering (P = 1). 10% SiO2 was associated with the highest hardness of A-2000 MFSE (32.7 ± .34; P < .001). The hot, humid natural weather conditions demonstrate a significant decrease in surface roughness and an increase in the hardness of A-2000 MFSE (P < .001). FTIR analysis confirmed that there were no changes in the chemical interactions between the silicone matrix with and without NFs.