Detecting bone changes along dental implants, after immediate or delayed loading, using digital subtraction on cropped panoramic radiographs. A prospective clinical trial with minimum 3-year follow up

Aim The aim of this study was to assess bone changes along implants after immediate or delayed loading, using subtractions of digital images originated from cropped panoramic radiographs and visual evaluation.

Materials and methods Eleven patients received 4 Ankylos implants interforaminal in the mandible. In 7 patients the implants were loaded immediately and 4 followed delayed loading. All patients were restored with a telescopic overdenture with Syncone abutments. From each patient 3 panoramic radiographs (PRs) were obtained: upon delivery of the restoration (T1), 6 months later (T2) and after 3 years (T3). 33 implants were finally selected. The radiographs were analyzed using the Emago® Software. The grey scale values were measured either manually (Stage A) or automatically (Stage B) in six areas (neck, middle and apex; both mesially and distally) along the implants€™ sides to evaluate the bone density during clinical function. Images were also visually evaluated by five observers to detect bone changes at the cervical implant area.

Results Strong positive correlation between the two stages (A and B) was found in all 3 examinations (Pearson€™s r 0.84-0.98). The t-test showed no statistically significant differences in grey level values between immediate and delayed loading (p<0.05) and no statistically significant changes in the visual evaluation among implants undergoing  either immediately or delayed loading (p<0.05).

Conclusions Emago® is a valuable method for bone level assessment around implants€™ neck. The grey value measurements of the bone adjacent to the implants that have been loaded either immediately or delayed do not significantly differ after 3 years of fuction. The visual assessment of the PRs images supports these findings.