We report a case of osseous dysplasia (OD) showing extremely rare clinical features. A 37-year-old Japanese woman was referred to our clinic complaining of a left alveolar bony swelling at an impacted canine. Radiographic examinations revealed a mixed radiopaque lesion involving the impacted left canine and also revealed an impacted left wisdom tooth with a cystic change and a clear radiopaque lesion suspected to be odontoma. All the extracted upper teeth and odontoma showed hypercementosis and the canine was fully involved in it. Histopathologically, they showed the same features and were diagnosed as OD. The findings of multiple OD from incompletely erupted teeth and odontoma in our case may well show that OD can arise from any tooth with periodontal ligaments and that focal OD can show expansive growth like the ossifying fibroma.