in vitro study: the effect of coca-butter application on the surface property of some glass ionomer cements

The purpose of the present work was to study the effect of coca butter application over the cement against the surface property for three brands of glass ionomer cement. The effect of water storage on the surface property of the cement was also studied. Scratch resistance test for cement surface was performed using a vicker Hardness apparatus under a load of 200 gm. And a speed of 0.5 m/min. Width of the scratch was measured using a stereo-microscope. The results showed that application of coca butter on cement surface had no effect for increasing scratch resistance. There was no significant difference among all the brands of cement tested for the scratch width. For all the brands investigated, the width of the scratch was not varied after four month of water storage

Interface bond strength and leakage of repaired composite resin

The bond strength of repaired composite resin [Lumicon] was examined under different conditions. Exposure to saliva for short period, 2 minutes, did not affect the bond strength, but 24 hours exposure to saliva or tea before repair caused a significant drop in the repair bond. The type of surface finish, smooth or rough, did not alter the results. It also seems that maturation of the composite rather than contamination which influence the repair strength. There was no dye leakage at the repair interface under any of the experimental conditions