Abstract : A considerable alveolar bone loss occurs follows tooth extraction, this bone resorption can compromise dental implant procedure, for this reason, the concept of socket preservation techniques was introduced, in which different materials placed into the extraction socket immediately after extraction to minimize alveolar bone loss. To evaluate the effects of autologous platelets poor plasma (PPP) and autologous platelets rich plasma (PRP) on the preservation of alveolar width in extraction socket with buccal dehiscence, and to evaluate the effect of PPP and PRP on the number of osteoblasts in the newly formed bone. Six adult pointer dogs were selected for this study, after flap reflection 3mm buccal dehiscence was created with trephine bur. Then the mandibular third premolar was extracted bilaterally. The extraction sites were randomly assigned to three groups: platelets poor plasma, platelets rich plasma and control. The experiment was designed to permit the examination of the extraction site after one and two months. the alveolar width measured histomorphometrically at three level that located at 1mm, 2mm and 3mm respectively from the top of the alveolar crest. The number of osteoblasts was calculated under the microscope in six fields representing the center of the extraction socket. There was no statistically significant difference in the alveolar width between all groups, regarding the osteoblast number it was significantly higher in the PRP group after one month but not after two months. While the number of osteoblasts in the PPP group was not significantly higher after one and two months. PRP and PPP may not adequately preserve the alveolar width after implantation of these materials in the extraction socket with buccal dehiscence. At the cellular level, PRP increased the number of osteoblasts in extraction site at 1 month. At later times there was no significant difference in the number of osteoblasts in the PRP and non-PRP graft