An implant-oriented method for dental digital subtraction radiography

The purpose of this study was to develop a method for navigation in digital dental radiographs. The proposed navigation method uses edge detection algorithms to locate the threads of the dental implant and construct an intra-image coordinate system. The coordinate system facilitates navigation in physical coordinates and calculations independent of differences in magnification. Our method can be combined with any contrast correction method for digital subtraction radiography. In this study, our method was combined with the Ruttimann et al. normalization method. The results show that simulated peri-implant bone density changes, invisible on clinically acceptable radiographs, could be detected. Furthermore, the method was sufficiently robust to allow for deviation in projection geometry of more than ten degrees. This study shows that the method can be used to analyze radiographic data from clinical studies on implants.