Chemical and mechanical degradation of nano-ionomer after two different surface protections: An in vitro study

To evaluate the effect of food-simulating liquids prior to brushing on surface roughness of a nano-ionomer restorative protected with two surface protection agents.

90 specimens were divided into three groups according to surface protection; the first group: no surface protection; the second group: copal varnish; the third group: light cure Ketac Glaze. Each group was subdivided into three subgroups relative to the immersion solution: artificial saliva; citric acid 0.02 M; or 50% ethanol. Specimens were stored for 7 days in one of the solutions in an incubator. One surface of each specimen was subjected to brushing with a sonic electric toothbrush while the other surface was not brushed. Surface roughness was measured with a stereo-microscope. Data were analyzed using one way ANOVA followed by paired t-test (P < 0.05).

The surface roughness of the nano-ionomer specimens immersed in ethanol was significantly higher than those immersed in citric acid. No significant differences were found between surface protection agents or between brushed and un-brushed specimens. The highest surface roughness mean value was recorded with brushed unprotected specimens immersed in ethanol. While the lowest surface roughness mean value was recorded with un-brushed copal varnish protected specimens immersed in ethanol.