Randa Abdel Rahman El Naggar, M.Adel Ezzat, M. Fouad Haridy And Shereen Hafez,

ABSTRACT
Objective: This Study Was Carried Out To Evaluate The Effect Of Bleaching On The Colour Change Of Two Types Of Composite Before And After Immersion In Coffee Staining Solutions.

Materials and Methods: A Total Of 144 Specimens Were Prepared In A Circular Teflon Mould (10 X 2mm), Then They Were Divided Into 2 Equal Groups According To Composites Used Amaris And Z350XT , Then They Were Divided To Three Subgroups According To The Bleaching Protocol ; No Bleaching, Bleaching After Staining And Bleaching Before And After Staining And Then Each Group Was Further Divided Into Three Classes According To The Staining Solutions Used ;artificial Saliva, Coffee And Coffee With Sugar And Creamer. Colour Measurements Took Place At Baseline, After Bleaching And After Staining Using X-rite Spectrophotometer According To The CIE L*a*b* Colour Space.

Results: The Results Revealed That Amaris Has The Highest Mean Colour Change, Bleaching Has A Non-significant Effect On The Colour Stability Of Composite Resin But It Can Lighten The Colour Of The Stained Composite And Finally Results Revealed That Coffee Has The Highest Mean Colour Change Among The Used Staining Solutions. Conclusion: Nanofilled Composites Are More Colour Stable Than Nanohybrid Composites, Also Bleaching Is A Viable Option To Remove Extrinsic Stains From Resin Composite.