Effect of silver nanoparticles addition on the surface roughness of feldspathic porcelain

OBJECTIVES: Among different types of ceramics, dental feldspathic porcelains are biocompatible dental ceramics that are used extensively for the preparation of fixed prostheses.
However, due to the lack of malleability or ductility, the surface fractures and surface roughness are usually seen in feldspathic porcelains. Adding nanoparticles with excellent mechanical strength to feldspathic porcelains is a suggested plan to compensate for the surface roughness issues. According to the literature, silver nanoparticles are biocompatible materials with anti-bacterial properties, causing an increase in fracture toughness and a change in the roughness properties of dental ceramics. In this study, the effect of silver nanoparticles on the surface roughness of feldspathic porcelains was investigated.

MATERIALS AND METHODS: The current study consisted of five groups of feldspathic porcelain: one control group and four intervention groups with different concentrations of silver nanoparticles (i.e. 100, 200, 350, 500 μg/mL of AgNp particles). The morphology of synthesized nanoparticle samples was evaluated using transmission electron microscopy.
The surface roughness was measured using profilometer in a 3D manner. For each sample, the total surface roughness was calculated by measuring the roughness for three different points with cutoff = 0.8 mm and by averaging them. Data were analyzed using analysis of variance and Tukey post-hoc test. Furthermore, the 2D surface roughness was investigated using electron microscope images from ceramic disks.

RESULTS: The results from field emission scanning electron microscopy showed a decrease in surface roughness after adding AgNPs. Surface data from the 3D profilometer showed that adding silver nanoparticles reduced the morphological parameters such as roughness average, root mean square value of roughness, and the height of roughness value. Statistical analyses showed that the positive effect of silver nanoparticles on decreasing surface roughness of feldspathic porcelain was significant.

CONCLUSIONS: According to the results of this study, the addition of AgNPs to the feldspathic porcelain up to 500 μg/mL reduced the surface roughness of the ceramic disks. The results of this study suggest an exponential relationship between nanoparticle concentration and surface roughness in which by increasing nanoparticle concentration the roughness is decreased more. However, a saturation point in the roughness-concentration profile is expected. More samples are needed for obtaining such a saturation point and its causal relationship with confounding factors.

CLINICAL SIGNIFICANCE: The results of this study indicated that adding AgNPs to feldspathic porcelain enhanced the surface roughness and in this way increased the mechanical strength of the sample. By adding a higher concentration of Ag- NP, the surface roughness will be decreased more, however, the percentage of enhancement is not changed significantly for values higher than 350 μg/mL. The results of this study indicated the importance of adding nanoparticles to feldspathic porcelain samples to enhance their durability and mechanical strength.

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