Evaluation of Digital Subtraction Radiography in Single Tooth Implant Follow-up

Evaluation of Digital Subtraction Radiography in Single Tooth Implant Follow-up
G.R. GILLESPIE, J.E. RUBENSTEIN, and L.G. HOLLENDER, University of Washington, Seattle, USA
March 2004
Clinical Implant Studies
Objectives: Digital Subtraction Radiography (DSR) detects tissue mass changes by digitally subtracting two superimposed radiographs. While the accuracy of this method shows in vitro to be greater than conventional radiographic methods, its efficacy in a clinical setting has not been established. This study compared conventional methods to DSR by evaluating single tooth implants during the first year of loading.
Methods: An ongoing clinical trial served as the database which included 45 single tooth implants, each followed up radiographically at baseline, one-month, and one-year following the placement of the completed restoration. Two examiners independently assessed the radiographs on a viewbox (conventional method) resulting in two databases: changes in bone height, and changes in bone density. The radiographs were then scanned into the computer using the EMS-DSR-1000 scanning device. The subtracted radiographs were assessed by the examiners. McNemar's test for difference of proportions was used to assess agreement between the two methods of assessment.
Results: Bone height changes showed 84% agreement between DSR and conventional method, (p = 0.45) indicating no significant difference. Bone density changes were analyzed by the Sign test and showed 77% agreement between DSR and conventional method, demonstrating a significant difference (p = 0.02). Looking solely at the number of times that bone formation was demonstrated, the proportion found by DSR was 22.7% versus only 2.3% by conventional method. McNemar's test for difference of proportions indicated a significant difference between the two (p = 0.004).
Conclusions: DSR identified statistically significant differences in changes in bone density when compared to conventional method, but no significant differences were demonstrated with regard to bone height changes. DSR seems to be a more sensitive methodology for assessing bone formation around single tooth implants. Further development of this database is currently underway for more detailed analysis.