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Since bone apatite is a carbonate apatite containing carbonate in an apatitic structure, carbonate content may be one of the factors governing the osteoconductivity of apatitic bone substitutes. The aim of this study was to evaluate the effects of carbonate content on the osteoconductivity of apatitic bone substitutes using three commercially available bone substitutes for the reconstruction of alveolar bone defects of a beagle mandible with simultaneous dental implant installation. NEOBONE®, Bio-Oss®, and Cytrans® that contain 0.1 mass%, 5.5 mass%, and 12.0 mass% of carbonate, respectively, were used in this study. The amount of newly formed bone in the upper portion of the alveolar bone defect of the beagle’s mandible was 0.7%, 6.6%, and 39.4% at 4 weeks after surgery and 4.7%, 39.5% and 75.2% at 12 weeks after surgery for NEOBONE®, Bio-Oss®, and Cytrans®, respectively. The results indicate that bone-to-implant contact ratio was the largest for Cytrans®. Additionally, the continuity of the alveolar ridge was restored in the case of Cytrans®, whereas the continuity of the alveolar ridge was not sufficient when using NEOBONE® and Bio-Oss®. Both Cytrans® and Bio-Oss® that has a relatively larger carbonate content in their apatitic structure was resorbed with time. We concluded that carbonate content is one of important factors governing the osteoconductivity of apatitic bone substitutes.

Objectives: Nasopharyngeal tonsilloliths (NT) and eustachian tube tonsilloliths (ET) are not as well-known to radiologists as palatine and lingual tonsilloliths. The aim of this investigation was to determine the prevalence and imaging characteristics of NT and ET using CT and panoramic radiographs. Methods: We retrospectively assessed the scans of 2244 patients who underwent consecutive CT and panoramic radiographs of the maxillofacial region. The prevalence, size, number, and position of NT and ET were analysed. Results: NT and ET were detected in 14 (0.6%) and 6 (0.3%) of 2244 patients on CT, respectively, but they were undetectable on panoramic radiographs. No significant difference was found in the prevalence with respect to sex. Although there was also no significant difference in the prevalence among age groups, tonsilloliths were most commonly noted in patients over 40 years old; they appeared as small and round calcified bodies, ranging from 1 to 3 mm in diameter. All NT were found 0 to 3 mm beneath the nasopharyngeal mucosal surface. Conclusions: The prevalence of NT and ET on CT was lower than that of palatine and lingual tonsilloliths. However, since they are encountered more frequently than clinically significant calcifying diseases such as retropharyngeal calcific tendinitis, clinicians should be able to correctly diagnose NT and ET based on their anatomical features.