| dc.description.abstract | Abstract
Introduction: Plaster used to make casts and dies in indirect casting techniques of restorations must have special characteristics for success, and proper setting time is one of them. Many mineral particles have been added to gypsum to improve the properties of the material. Industrially, some chemicals are added to dental plasters to speed up or delay the setting time. Today, nanotechnology is used with the main purpose of improving the mechanical properties of materials used in dentistry, including plaster. Due to the fact that the effect of adding silica nanoparticles on the setting time of dental stone has not been studied so far, in this study, we examined the setting time by adding different percentages of silica nanoparticles (0.5, 1, 2, 5) to dental stone type 4, which is to complete and to continue the previous studies. If the desired results are achieved, these particles can be used to improve the properties of dental stone.
Materials and methods: In this study, silica nanoparticles (silicon dioxide) were used with percentages of 0.5, 1, 2, and 5% by weight. 40 samples were classified into 5 groups (0.5%, 1%, 2%, 5% and control group). Then the prepared samples were checked in terms of setting time. The samples were prepared according to the manufacturer's instructions and tested according to the ISO6873 standard using the Vicat device. The elapsed time from the start of mixing until the needle can no longer fully penetrate the mass was measured with a cornometer and the setting time was obtained. Mean and standard deviation were used to describe quantitative data. One-way ANOVA test with the help of SPSS.26 was used to compare the results. The normality of the data was checked using the Kolmogorov Smironov test. A significance level of P<0.05 was considered.
Results: Adding silica nanoparticles to dental stone increases the setting time, and this increases with increasing nanoparticle concentration. The difference in setting time between the control group and the group of dental stone containing 0.5% nanoparticles with the group of dental stone containing 5% nanoparticles was significant (P value < 0.05).
Conclusion: The addition of silica nanoparticles to dental stone type 4 increases the setting time, and this increase is significant in the 5% concentration compared to the control group and the 0.5% concentration, but it is within the ISO range and due to the advantages of adding nanoparticles, it can be used. | en_US |
