Objective The present study aimed to evaluate the histological outcome of tunnel beta-TCP blocks grafting in extraction sockets missing the buccal bone wall, after 6 months of healing. Background Tunnel beta-tricalcium phosphate (beta-TCP) blocks made of randomly organized tunnel-shaped beta-TCP ceramics appeared promising for alveolar ridge preservation in tooth extraction sockets missing the buccal bone, in a previous study in dogs, with a 2-month healing time. Methods In six beagle dogs, the maxillary first premolars were extracted and the buccal bone was surgically removed to create bone defects of 4 mm (mesio-distal) x 5 mm (apico-coronal) x 4 mm (bucco-palatal). Thus, extraction sockets missing the buccal bone plate were grated with tunnel beta-TCP blocks (test) or left empty for spontaneous healing (control). Histology/histomorphometry was performed after 6 months of healing. Results The horizontal bucco-palatal width of the alveolar ridge was significantly greater at test sites than at control sites. The amount of mineralized tissue was greater at test sites (57.8% +/- 11.1%) than at control sites (28.9% +/- 8.5%), while the amount of connective tissue was significantly greater at control sites (41.7% +/- 6.4%) than at test sites (19.6% +/- 9.2%). No significant difference was found between sites in terms of basic multicellular units and bone marrow. Residual beta-TCP at test sites was 5.8% +/- 3.2%. Conclusion Grafting with tunnel beta-TCP block significantly limited the resorption of the alveolar ridge at extraction sockets missing the buccal bone compared with sites left to heal spontaneously, even after 6-month follow-up.