Aim:Investigate effect of repressing of Lithium disilicate ceramic with different weight percentages on color,translucency & bond strength with veneering material.
Materials & Methods:Thirty discs were constructed & divided according to weight percentage of newly pressed & repressed ceramic.Group1 samples were 100%new ceramics. Group2 discs were 75%new,25% repressed ceramic. Group3 samples were 50% new,50%repressed ceramic. Group4 samples were 25%new,75%repressed ceramic. Group5 discs were 100%repressed ones.One sample from each group was randomly selected for SEM test.The remaining discs in each group(5 samples)were used to test color & translucency, then these samples were veneered with porcelain & subjected to shear bond strength test.
Results:Results showed ΔE of the tested groups were in the clinical accepted range except the 100%repressed group.There was no significant difference between all tested groups as related to translucency.As regard bond strength, there was no significant difference between 100%new group & the 75%new+25%repressed group. No significant difference was recorded between the 75%new+25%re-pressed group and the 50%new+50%re-pressed group.There was a significant difference between 100%new group & 50%new + 50%repressed group which was also different than 25%new+75%re-pressed group.There was a significant difference between the 100%re-pressed group & the 25%new+75%re-pressed group.
Conclusions:The mix of new ingot with repressed ceramic are in the clinical acceptance range as regard ΔE.The 100 % re-pressing ceramic can affect the final colour.Ceramic repressing has no significant effect on translucency.Weight percent of repressed ceramic has a direct effect on bond strength to veneering material as increasing the percentage of repressed ceramic led to a decrease of bond strength values.