Conventional procedures for the preparation of abutment teeth often involve major removal of tooth structure. However, when the abutment teeth are sound, conventional full coverage procedures seem quite radical. The resin-bonded fixed partial dentures have gained immense popularity in recent years as they are more conservative, esthetic, economic and easily fabricated. However debonding is considered the most common cause of failure of resin bonded prosthesis. Improvement have been suggested for resin bonded prosthesis techniques that are related to both clinical and laboratory phases to reduce debonding. The objective of the study were to compare the effects of different groove lengths and thickness of retainers on retention of maxillary anterior base metal resin bonded retainers.