Degree of conversion and Knoop microhardness of a silorane composite

Abstract

Purpose: To evaluate the relationship between degree of conversion and microhardness of a composite based on silorane monomers (Filtek P90-3M ESPE). Methods andmaterials: The specimens (n=10/gp, cylindrical 5mm× 2mm, light-cured 1100mW/cm2) were divided into 5 groups according to the energy amount obtained by the variation in the irradiation time (8, 12, 16, 20 and 24 J/cm2). The DC was performed using a FTIR (Excalibur 3100) and ATR (Miracle) in real time. Sixteen scans of spectra were performed (4cm−1/20min). The Knoop Hardness Number (KHN) was performed (Durimet) in a total of 10 indentations/specimen bottom (30 s/25 g). The data were tested for normality and homogeneity and then subjected to ANOVA (5%). Results: The data were presented on table. DC: p=0.324; KHN: p<0.001. The groups of 24 and 30 J/cm2 had higher hardness than the groups of 3 and 12 J/cm2. The 18 J/cm2 group had similar values to 12 and 24 J/cm2 groups. The Pearson regression test showed a strong correlation DC/KHN (p=0.002, R2=0.976). The greater DC, higher KHN. Conclusion: DC was not influenced by the energy, despite the trend of increasing conversion function of the energy amount has been observed. The progressive variation of the energy amount influences the increase of KHN. There is positive correlation between KHN and DC.