Methods: 6mm thick plates of porcine illiac cancellosus bone are submittet to computer tomographic examination. At defined sites on these plates implants (Branemark® Mk4 (a) and ITI® 4mm (b)) are placed using torque measurements (Nobel Biocare Osseocare® 600 drilling device) during placement, subsequently Periotest® measurements (pt) and Ostell® resonance frequency testing (rendering: ISQ) are performed. Finally the implants are submitted to push-out-testing(Zwick® UPM). Statistical analysis using SPSS® includes descriptive basic statistics, Wicoxon-test and Spearman-correlations.
Results: Both types of implants show a slightly different behaviour. The best correlations are found between push-out-force and CT-bone-density at implant site (a: 0.92 and b: 0.87, p<0.001) as well as between push-out-force and insertion torque (Spearman-corr. a: 0.87 and b:0.84, p<0.001), a much weaker correlation between push-out-force and periotest value (a: 0.74 and b:0.53) as well as push-out-force and ISQ (a: 0.66 and b: 0.57).
Conclusions: If we agree on the fact, that the push-out-force, the ultimate axial holding power of an implant serves as a measure for its primary axial stability, we must conceed, that so far there is no simple measurement available for the clinical situation, which can be employed to determine the initial load bearing capacity of an implant with high precision.