Abstract: Aim: The aim of present study was to evaluate and compare radiographically the amount of crestal bone resorption during healing and loading period in single implant versus two implant retained mandibular overdentures in totally edentulous patients. Materials & Methods: A total of 20 edentulous patients (12 male and 8 female) with age range of 58.6 years were included in this clinical trial which was completed in 4 phases (clinical and radiographic diagnosis, surgical phase, implant loading phase and bone level measurement phase). The eligible patients were randomly allocated in 2 equivalent groups of 10 participants each per group. The allocation was in 1:1 ratio via randomized chit method. Group I included the case group i.e. single implant and Group II included the control group i.e. two-implants located in mandible. A total of 30 implants were placed in Group I and 20 implants in Group II. Digital intraoral peri-apical radiographs (RVG 5100) were used for measuring the bone level immediately after implant surgery, 1 month, 3 months, 4months and 6 months. Result: The present study showed that there was a mean crestal bone loss of 0.7mm between the tip of the implant and alveolar crest at the end of 6 months after implant placement in single implant group I while 0.67mm in case of Group II two-implant retained mandibular................