Twelve sites were augmented in the posterior mandible of six patients. The ages of patients participating in this study ranged from 25- 47 years (four females and two males).Cortico-cancelus autogenous bone block collected from the chin was utilized as a grafting material for ridge augmentation. In each patient one side augmented using onlay bone graft, and the other side using inlay-interpositional bone graft. The inlay side prepared using Piezosurgery Device for bone cutting procedures during osteotomy preparations. Cone-beam cross-section computed tomography images was used for procedure planning and follow up at 1 and 4 months postoperatively. Histological assessment was performed at 4 month after taking core biopsy during implant placement. The onlay side showed higher bone gain value of 3.97mm immediately and 2.90mm at four months post-operatively compared to the inlay which showed 2.60mm immediately and 1.14mm at four months post-operatively. The onlay side showed 1.07 mm (23.18%) of bone loss while the inlay side had about 1.46 mm (90.03%) of bone loss. The differences between the two sides were not statistically significant. The success rate for inlay side was 83.33% with one graft lost while the onlay side had 100% success rate.