Background: Autogenous bone grafts are the gold standard for being used as graft materials in maxillofacial surgery. However, a limited amount of these materials is available from the donor site, and there is also more need for a larger operating area and a second surgery, which frequently leads to unreliable graft incorporation, tooth ankylosis, and root resorption. Therefore, newer bone graft substitutes have been developed as alternatives, among which eggshell powder has been introduced as a bone substitute. This study aimed to evaluate the biocompatibility, resorption kinetics, and osteoproductivity of the unprocessed, CMC-coated, and gelatin-coated ostrich eggshell particles. Methods: Four half-thickness calvarial defects were created in each animal. At the end of the 1st and 3rd months, the defected sites were investigated by clinical, histological, radiological and histomorphometrical methods. Results: Coating the eggshell particles with CMC and gelatin facilitated their surgical application and contributed to new bone formation. However, their newly formed bone rate at the 3rd month was lower than those of the unprocessed eggshell particles. The CMC coating was more effective than gelatin coating in the bone modeling process. Conclusion: Ostrich eggshell particles either in native form or coated with CMC could be used as a bone filler for supporting new bone formation and healing in treatment of osseous defects.