Abstract
These 13 cases of paranasal sinusitis clinically diagnosed as of dental origin constituted 7.8% of all the patients of paranasal sinusitis who made visits to the authors' hospital during the same period of time. The majority of teeth causing sinusitis was the first molar of the upper jaw on the affected side. In all these cases the responsible teeth had also some chronic change without exception. Especially, it is remarkable that the periodontoclasia as excitnig causes not of rare occurrence. It was proven roentgenologically and on the occasion of operation that the inflammation of maxillary sinus of dental origin could spread often into the neighboring paranasal sinuses. Prognosis was generally better than with the sinusitis of nasal origin.
