For radiation dose reduction of patients in dentistry, it is a significant method to use new high-speed dental X-ray film, EKTASPEED.

The purpose of the present study is to compare the characteristic curves by EKTASPEED and ULTRASPEED used to this time and to compare diagnostic performances were examined on image quality and granulation of these radiographs created on molar portion in mandibular bone with bone phantom.

The characteristic curve of EKTASPEED was approximately parallel to that of ULTRASPEED and gamma was nearly equal each other.

The speed of EKTASPEED was twice as fast as of ULTRASPEED. Radiographs by EKTASPEED were somewhat rough in granulation, whereas there were no significant differences between EKTASPEED and ULTRASPEED on image quality.

Diagnostic performances of EKTASPEED were almost same as those of ULTRASPEED.

The results suggest that the choice of new high-speed dental X-ray film, EKTASPEED, is useful for radiation dose reduction of patients.