Effect of ultrasonic excitation on the porosity of glass ionomer cement: a scanning electron microscope evaluation.

BACKGROUND: Ultrasonic excitation (US) was applied to glass ionomer cement (GIC) during early set time to increase the advantageous properties of this material. PURPOSE: The aim of this in vitro study was to assess the inner porosity of GIC after US. STUDY DESIGN: A total of 16 specimens, for each material, were prepared from high-viscosity GIC Fuji IX GP, Ketac Molar, and Ketac Molar Easymix. Half of these specimens (n = 8) received 30 s of US during the initial cement setting. After completion of the material setting, specimens were fractured and observed by scanning electronic microscopy to quantitatively assay porosity inside the material using Image J software. RESULTS: Statistical data analysis revealed that US reduced the porosity for all tested materials (P ≤ 0.05). The following reductions (expressed in percentages) were achieved: Fuji IX--from 3.9% to 2.8%; Ketac Molar Easy Mix--from 4.4% to 2.6%, and Ketac Molar--from 2.4% to 1.6%. CONCLUSION: Under the tested conditions, US was an effective method for porosity reduction inside the material.