Mohammed TahaElmansoury, Dr. Ashraf Anwar Gebreel ⁽¹⁾, Prof. Salah Abdel Fattah Hegzay ⁽²⁾ (1) Lecturer of prosthosontics, faculty of dentistry, Mansoura University. (2) Professor of prosthosontics, faculty of dentistry, Mansoura University. Abstract: Purpose: evaluate and compare peri-implant soft tissue changes of three implant assisted mandibular overdenture with either ball or locator attachments.  Material and methods:Six completely edentulous male patients received three implants in the mandibular canine areas bilaterally and in midline region by flapless surgical protocol using stereolithographic surgical stent. After three months of healing period (delayed loading protocol), patients were randomly assigned into two groups as mandibular overdentures were connected to the implants with either ball (group I, GI) or locator (group II, GII) attachments. Peri-implant soft tissue health was evaluated clinically in terms of plaque index (PI), gingival index (GI), bleeding index (BI) and probing depth (PD) were measured at buccal, mesial, lingual and distal surfaces of each implant. Evaluation was performed at time of insertion (T0), 1 month (T1), 3 months (T3) and 6 months (T6) after overdenture insertion. Results: Mean Plaque index significantly increased with advance of time in both groups with a statistically significant difference in Plaque index between group I and group II after six months of function (T6). The lingual site recorded the highest plaque index at different observational times. The middle implant recorded the lowest plaque index and no difference between right and left implants. Regarding gingival and bleeding indices in this study, it was obvious that gingival index findings were nearly resembles plaque index. Probing depth scores significantly increased with advance of time in group I only except at T1. There was a significant difference in probing depth between group I and group II after three and six months of function (T3, T6). Despite of distal surface of right and left implants presented the only higher probing depth at T3 and T6, There was no significant difference in probing depth neither different sites of measurements (buccal, mesial, lingual and distal) nor different implant locations (right, left and middle) at different observational times. Conclusion:Placing implants in three linear position in the anterior area of mandibular arch to use mandibular assisted overdenture is a reliable treatment regarding soft tissue outcome. On choosing the attachment used comparing ball and locator in three implant assisted overdenture, the locator attachment is more preferred regarding perimplant soft tissue outcome.v