Purpose: A bone defect model simulating an extraction socket with buccal dehiscence was designed to investigate the usefulness of a composite of beta-tricalcium phosphate (ß-TCP) and a collagen sponge, ß-TCP/ collagen (TCP/Col) for socket preservation. Materials and Methods: Following the extraction of the maxillary second and third premolars of 13 beagle dogs, a bone defect with buccal dehiscence (5 × 3 × 7 mm) was prepared. The defects were filled with either TCP/Col, ß-TCP, collagen, or left intact (control) and evaluated at 4 and 8 weeks after surgery. A total of three micro-computed tomography (micro-CT) images were selected, and the area size occupied by the newly formed bone and residual TCP was measured. Newly formed bone and residual TCP in the bone defect site of the specimens was also measured and evaluated. Results: No evidence of postoperative infection was found in all cases. At 4 weeks after surgery, the TCP granule was retained in the bone defects and active bone formation was observed in the TCP/Col group and the ß-TCP group, whereas in the collagen and the control groups, connective tissue grew into the defect. In the TCP/Col and ß-TCP groups, morphologically well-preserved alveolar ridges were observed; most TCP granules grafted in the defects were resorbed and only a few residuals were evident at 8 weeks after surgery. Conclusions: These results exhibited that the TCP/Col composites could sufficiently maintain bone width and height for the preservation of the extraction socket with buccal dehiscence while preventing epithelial in-growth. In addition, TCP/Col in an easily handled spongeous form could provide a better intraoral manipulation capability than TCP granules alone and was considered to be suitable as a bone grafting material used for alveolar ridge preservation.