The implant supported overdentures offered better chewing and masticatory functions. Locator attachment has more advantages than other attachment types. Aim: The aim of the study was to compare radio-graphically the effect of implant locator's height on peri-implant bone height and density in mandibular over-denture. Patients and method: Twelve completely edentulous male patients had received conventional complete maxillary dentures and mandibular overdenture that retained by two implants that

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... ere inserted in the canine region by the help of CAD/CAM based surgical guides. The patients were divided randomly into two groups. Group I: the patients were received locator abutment with 1mm in height. Group II: the patients were received locator abutment with 3mm in height, a series of cone beam radiographs were taken at 0, 6, 12 and 18 months starting from the first day of lower over denture installation, peri-implant bone changes regarding height and density were estimated. Results: It was found that the mean marginal bone loss measurements were relatively higher for group I than group II with non-statistical significant difference. The average difference in bone density measurements around the implants for both groups showing initial increase followed by marked decrease through the follow up periods. Conclusion: locator height has an effect on peri-implant bone height, bone density.