Reducing the surface roughness of dental acrylic resins by using an eggshell abrasive material.

STATEMENT OF PROBLEM: Excessive surface roughness of denture base resins adversely impacts oral health. PURPOSE: The purpose of this in vitro study was to examine the abrasive potential of eggshell powder in reducing the surface roughness of denture base resins. MATERIAL AND METHODS: Thirty poly(methyl methacrylate) specimens were fabricated and polished with eggshell powders of different particle sizes and with pumice. The average surface roughness (Ra) after polishing was measured with a profilometer. Scanning electron microscope and optical electron microscope techniques were used to assess the surface roughness morphology of the specimens. ANOVA was used to analyze the Ra values. The Tukey honest significant differences and Bonferroni tests were used to identify differences between the 2 abrasive materials (α=.05). RESULTS: Significant differences in the Ra values were observed between the fine and medium eggshell powder abrasives (P<.05). Similarly, significant differences were found between pumice and the fine eggshell powder abrasives (P<.001). No significant differences were found between pumice and the medium eggshell powder abrasive (P>.05). Specimens polished with pumice had the highest Ra values, whereas specimens polished with the fine eggshell powder abrasive had the lowest Ra values. CONCLUSIONS: By connecting the Ra values to the threshold limit value of 0.2 µm, eggshell powder abrasive finished denture acrylic resin surfaces better than pumice.

Physicochemical characterization of a dental eggshell powder abrasive material.

BACKGROUND: This study aimed to determine the physicochemical characteristics of an eggshell-based dental abrasive material. METHODS: The eggshell powder abrasive material (EPAM) was synthesized by ball milling eggshell powder and surfactants. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and a laser diffraction particle size analyzer (PSA) were used to characterize EPAM. In addition, the abrasive characteristics of EPAM were evaluated by comparison using poly(methyl methacrylate) (PMMA) resins. Surface roughness (Ra) was measured using a profilometer. RESULTS: The FTIR spectroscopy and XRD analysis confirmed that the carbonate product was primarily calcite (97.3%) with traces of graphite 2H (1.3%) and thenardite (1.4%). The TEM imagery revealed irregular particles in EPAM. The PSA analysis of the particle size distribution showed EPAM to be a superfine powder (0.3 µm to 50 nm). In addition, the 50-nm EPAM (Ra = 0.04 µm) measured the lowest Ra value when compared with pumice (Ra = 0.08 µm). CONCLUSIONS: The salient features of this study indicate that EPAM can naturally replace calcite, which is generally mined and used as a dental abrasive material. In addition, and regarding the abrasive characteristics of EPAM in reducing the surface roughness of PMMA resin specimens, this study conclusively showed that EPAM effectively reduces the surface roughness below the threshold limit value of 0.2 µm. Potentially, EPAM could reduce waste disposal problems while enabling an economic benefit from using eggshell waste material.