Submit Date : 2022-01-19 • Accept Date : 2022-03-03 • Available online: 2022-03-30 • DOI : 10.21608/edj.2022.117191.1953 Print ISSN 0070-9484 • Online ISSN 2090-2360 Fixed Prosthodontics and Dental Materials EGYPTIAN DENTAL JOURNAL Vol. 68, 1647: 1654, April, 2022 www. eda-egypt.org Article is licensed under a Creative Commons Attribution 4.0 International License * Researcher at Restorative and Dental Materials Department, Oral and Dental Research Institute, Cairo. ** Lecturer of Dental Biomaterials, Prosthetic Dentistry Department, Biomaterials Division, Faculty of Dentistry, King Salman International University, El Tur, South Sinai,Egypt. INTRODUCTION The increasing demand to have white teeth and thus a more pleasant smile has become the primary need of patients today and having discolored teeth is considered unacceptable to patients (1) . Treatment protocols of discoloration varies from the most conservative procedure as bleaching to extensive partial coverage veneer. In general, overcoming EFFECT OF ADDITION OF CALCIUM PHOSPHATE NANOPARTICLES TO BLEACHING AGENTS ON SURFACE HARDNESS AND COLOR CHANGE OF ENAMEL. AN IN VITRO STUDY Amal M. El Shahawi * and Reem Ashraf ** ABSTRACT Purpose: The objective of this study was to evaluate the effect of incorporation of nanocalcium phosphate into the bleaching agent on microhardness and color change of enamel. Materials and Methods:30 maxillary anterior teeth were divided into three groups: group (1): no bleaching agent, group (2): bleached with 40% carbmide peroxide, and group (3): bleached with 10 wt% of prepared nanocalcium phosphate modifed carbamide peroxide. All samples were tested for color change using spectrophotometer, and hardness was evaluated using Vickers hardness test before and after bleaching. Results: No signifcant change in color was observed for both groups although group (2) showed yellowish color change. Hardness was increased for group (3) that was confrmed by SEM and EDEX results. Conclusion: Bleaching using nanocalcium phosphate particles had the highest hardness results and at the same time improved the remineralization effect on the tooth surface. KEYWORDS: calcium phosphate nanoparticles, carbamide peroxide, hardness, color change, bleaching agents