A posteriori registration and subtraction of panoramic compared with intraoral radiography

Objectives. To demonstrate the feasibility of panoramic image subtraction for implant assessment. Study design. Three titanium implants were inserted into a fresh pig mandible. One intraoral and 2 panoramic images were obtained at baseline and after each of 6 incremental (0.3, 0.6, 1.0, 1.5, 2.0, 2.5 mm) removals of bone. For each incremental removal of bone, the mandible was removed from and replaced in the holding device. Images representing incremental bone removals were registered by computer with the baseline images and subtracted. Assessment of the subtraction images was based on visual inspection and analysis of structured noise. Results. Incremental bone removals were more visible in intraoral than in panoramic subtraction images; however, computer-based registration of panoramic images reduced the structured noise and enhanced the visibility of incremental removals. Conclusion. The feasibility of panoramic image subtraction for implant assessment was demonstrated. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108:e39-e45)