Dynamic behavior of implants as a measure of osteointegration

Aim of the study

To compare, in the dog, the evaluation of osseointegration by measuring dynamic or impedance mobility (the response to a mechanical stimulus using an instrument) with three other measures (clinical mobility, histology and radiographic assessment).

Materials and methods

Three months after bilateral extraction of P1, P2, P3 and P4, six submerged Nobel implants (one was covered in tin in order to prevent osseointegration) were placed and stage two surgery undertaken after 3 months. Two months later, three groups of implant (all osseointegrated by stage 2, except the « tin » group) had been created (6 were left osseointegrated, 17 had ligatures applied and the « tin » group), in order to simulate the various clinical conditions conducive to success or failure. Clinical measurements (« manual » mobility, standardised radiography and dynamic mobility) were undertaken after stage 2 surgery and at 6 months. Histology was undertaken at 6 months.

Conclusion

In contrast with the osseointegrated implants, the non-integrated implants showed non-linear firmness during the impedance tests.

There was agreement between the mechanical impedance measurements and the clinical and histological methods of assessing osseointegration. However, the radiographs did not always demonstrate the real state of osseointegration.

The parameters for the osseointegrated implants did not vary with time.

Commentary

This study adds to the pathway of research begun by Meredith (1996) on the response of implants to mechanical resonance tests, in order to have a truly reliable clinical means of evaluating osseointegration.

In the present case, the agreement between the various parameters is reassuring but, within the framework of this study, the impedance test does not seem to bring a more discriminating evaluation of osseointegration compared with basic clinical measurements.

It would have been interesting to recall the values obtained with this type of instrument in other studies, in order to have a reference point and to appreciate the results of this study. Perhaps this explains the total absence of a « discussion » part of the article.