Background: Bone grafting is a common technique in Oral and Maxillofacial surgery to replace missing bone. Grafting materials include autografts, allografts, xenografts and synthetic bone substitutes. Two synthetic bone materials are currently available; porous titanium granules and nanocrystalline hydroxyapatite. Objectives: This study compared the use of Porous titanium granules (PTG) versus Nanobone® in healing of mandibular defects in dogs and this was estimated by histological and histomorphometric analysis. Materials and Methods: The study was conducted on 10 healthy experimental dogs. An osseous defect of 10mm depth and 10mm width was created in the premolar area of both right and left sides of the mandible. The right side defects were grafted with PTG while the left side defects were grafted with Nanobone®. Histological and histomorphometrical evaluation was carried out to monitor bone healing and quantify the bone volume with both PTG and Nanobone® at 3, 6 and 12 weeks intervals post-operatively. Results: The mean bone volume value with PTG was 773.4 ± 499.4 on the 3rd week, then increased on the 6th week to be 10125.3 ± 19287.3 and 2676.0 ± 1388.2 on the 12th week. The mean bone volume value with Nanobone® was 525.5 ± 332.1 on the 3rd week, then on the 6th week it became 287.4 ± 322.5. There was a statistically significant increase on the 12th to be 1976.8 ± 1568.1. . There was a statistically significant difference regarding the mean bone volume value between the two groups. Conclusion: Both PTG and Nanobone® have osteoconductive properties and are effective in healing bone defects, but the histomorphometric analysis quantified the bone volume with both PTG and Nanobone® and revealed that the maximum amount of the total regenerated bone was seen in the PTG group; bone was formed within its porosities