Supervisor : Omaima Elmahallawi, Lomaya Ghanem.Sayed, Ahmed Sohail,2022-01-172022-03-272022-01-172022-03-272020.EG-CaMIUThs359https://iorep.miuegypt.edu.eg/handle/20.500.13071/74DISSERTATION NOTE-Degree type M.Sc.DISSERTATION NOTE-Name of granting institution Misr International University, Faculty of Oral and Dental MedicineIncludes Arabic Summary.Includes bibliographic references (pages 84-98)Esthetic dentistry are increasing this days where patient needs getting higher demanding better natural appearance. Recent technologies and materials make it easier for patient and dentist reaching perfect results. Ceramic laminate veneers are the best to be used regarding biological, mechanical and esthetics to reproduce the natural tooth shape with great color stability and periodontal biocompatibility. Laminate veneers are an ultraconservative restoration that only needs a minimal amount of reduction, prepared just in the enamel, to achieve the best bond strength and avoid or decrease postoperative sensitivity, also used correctly to achieve functional and aesthetic rehabilitation. New generations of adhesive resin cements increase the success and longterm survival of laminate veneers. They give better bonding between tooth and restoration. They proved to be a suitable treatment modality in anterior teeth restoring esthetics and function. Sometimes laminates need to be replaced, due to faulty cementation, caries, leakage, fracture, or due to patient dis-satisfaction with the results. Till recently the only way to remove a laminate veneer was by using rotary instruments to cut it away, this is a procedure that is both time consuming and destructive rendering it hard to prevent damage as the laminate veneer, the cement and the tooth structure are almost of the same color. So it is difficult to distinguish between them even under magnification. Nowadays, laser was introduced in the medical and dental fields. More recently, Laser is considered the highest tech instrument in dentistry like for computer aided design and computer aided manufacturing (CAD/CAM) and radiovisiography (RVGs). Laser have many types with different uses. The introduction of laser for debonding of laminate veneers has proved to be useful to preserve the tooth structure and maintain the integrity of the laminate veneers, offering better results. However, the effect of the laser on the tooth structure or the laminate veneer is still controversy and lack of evidence about the laser parameters and time to use for debonding. Consequently, this study aimed to study the effect of Er,Cr:YSGG laser on tooth structure chemistry and topography after debonding of laminate veneer.98 pages : illustrations, photo ; 29 cmtextapplication/pdfengFixed Prosthodonticstext