The accuracy and reliability of radiographic methods for the assessment of marginal bone level around oral implants

Objectives: To determine the accuracy and reliability of radiographic methods for assessment of the marginal bone level around oral implants in human cadavers. Methods: In three human cadavers two implants were placed according to the Instruction Manual for the Branemark System(R). One implant was installed in the canine and one in the premolar region of the left mandible. For each implant, conventional and digital intra-oral paralleling radiography were performed. Digital images were printed with a Kodak 1200 Distributed Medical Imaging printer(R) on blue transparent film, glossy and plain paper. Furthermore, digital scanographic, panoramic and tomographic images were taken with the Cranex Tome(R), multimodal X-ray unit and printed on Agfa Drystar TM 1 B(R) transparent films. All images were evaluated by five dental specialists. Data were statistically compared with real measurements of the marginal bone level on the human cadavers, performed by the same group of observers. Intra- and inter-observer variability were determined. Results: Digital intra-oral images on glossy paper showed the smallest absolute difference between real and measured bone level, followed by digital intra-oral images on film and on plain paper, conventional intra-oral images on analogue film, panoramic, scanographic and tomographic images on film. The difference between real and radiographic measurements was not statistically significant (P > 0.05) for all radiographic techniques. Intra- and inter-observer reproducibility was high for all techniques. Conclusions: The selected imaging techniques showed an acceptable accuracy for peri-implant bone level measurements with an overall error of less than 0.5 mm. Intra-oral images showed the smallest absolute differences.