How to Cite: Negm, H. M., Abi-Elhassan, M. H., Ahmed, I. H., Abo Elezz, A. F., & Elhossary, W. (2022). Evaluation of microtensile bond strength of nanoclay modified adhesive systems using bulk fill resin composite. International Journal of Health Sciences, 6(S1), 7229–7242. https://doi.org/10.53730/ijhs.v6nS1.6832 International Journal of Health Sciences ISSN 2550-6978 E-ISSN 2550-696X © 2022. Manuscript submitted: 18 Feb 2022, Manuscript revised: 09 March 2022, Accepted for publication: 27 April 2022 7229 Evaluation of microtensile bond strength of nanoclay modified adhesive systems using bulk fill resin composite Hassan M. Negm Lecturer of Conservative Dentistry Dept., Conservative Dentistry Department, Faculty of Dentistry, 6 th October University, Egypt Corresponding author email: hassannegm341@gmail.com / hassannegm_34@yahoo.com; Mohsen H. Abi-Elhassan Professor of Conservative Dentistry, Faculty of Oral and Dental Medicine, Cairo University; Vice-dean of Environmental Affairs and Community development-6 th October University, Egypt Email: abielhassan@yahoo.com Ibrahim Hussein Ahmed Professor of Surgery, Anaesthesiology and Radiology, Department of Surgery, Anesthesiology and Radiology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522, Egypt Ahmed F. Abo Elezz Assistant professor of Operative Dentistry, Faculty of Dentistry, Suez Canal University, Ismailia, 41522, Egypt; Email: ahmed_elezz@yahoo.com Wafaa Elhossary Lecturer of Oral Pathology, Faculty of Dentistry, Suez Canal University Ismailia 41522, Egypt; Email: whossary6@yahoo.com Abstract---Background: Composite polymerization creates internal stresses that cause bond loss at the tooth composite interface, cuspal deflection, and enamel crack formation; that are potential restoration failure. Aims: The aim of the present study was to evaluate micro- tensile bond strength of bulk-fill resin composite to human dentine of extracted teeth using nanoclay modified adhesive system (with and without organic modifier). Materials and Methods: A total of 120 caries-free permanent human posterior teeth were used and classified three groups according to adhesive system (each with 40 teeth);