Purpose: This research was aimed to study compare the effect of presence of strategically placed posterior implants and cantilevered bars on peri-implant bone loss and posterior bone area index for implant retained mandibular complete overdenture. Materials and Methods:In total, 10 completely edentulous patients restored with maxillary complete denture and mandibular complete overdenture, 5 patients received 2 implants in canine region of the mandible splinted with cantilevered bar (group I), 5 patients received 4 implants (2 in canine region and 2 in first molar region). The implants in the canine region were splinted with a resilient bar and healing abutments were connected to the posterior implants (group II), participated in this study. Marginal bone height changes were evaluated by standardized periapical radiographs and posterior alveolar bone resorption was evaluated by panoramic radiographs. Results: 1) Vertical bone loss (VBL) increased significantly with advance of time in both groups. Group I recorded significant higher VBL than group II at different observation times. In group II, Posterior implant recorded significant higher VBL than anterior implants at different observation times. 2) There were no significant differences in horizontal bone loss (HBL) observed between groups, implant positions and observation times. There was no significant correlation between group, age, and initial height of the mandibular ridges and HBL. 3) Posterior area index (PAI) decreased significantly with advance of time in group I and no significant difference in PAI was observed between observation times in group II. Group I recorded significant higher PAI difference than group II after 24 months of overdenture insertion. Conclusion: 1) Strategically placed posterior dental implants for implant retained mandibular overdenture is recommended to solve the rotation of straight single bar overdentures than cantilevered bar design as it was associated with significant reduction of peri-implant and posterior mandibular bone loss. However, this design increased the marginal bone loss of the posterior implants. 2) Both age of the patient and initial height of the mandibular ridge have an important a significant correlation with the residual alveolar ridge and implant marginal bone loss after two years of overdenture insertion. 3) This study recommends periodic monitoring the ridge–base relations by relining of the base to compensate for the posterior ridge resorption or attrition of the artificial teeth to achieve long term serviceability. # Cited from thesis submitted by Mohammed Mahmoud Alokda for requirement of Doctorate degree of prosthodontics