Mechanical insertion properties of calcium-phosphate implant coatings.
OBJECTIVE
To investigate the influence of protein incorporation on the resistance of biomimetic calcium-phosphate coatings to the shear forces that are generated during implant insertion.


METHODS
Thirty-eight standard (5 × 13 mm) Osseotite® implants were coated biomimetically with a layer of calcium phosphate, which either lacked or bore a co-precipitated (incorporated) depot of the model protein bovine serum albumin (BSA). The coated implants were inserted into either artificial bone (n=18) or the explanted mandibles of adult pigs (n=12). The former set-up was established for the measurement of torque and of coating losses during the insertion process. The latter set-up was established for the histological and histomorphometric analysis of the fate of the coatings after implantation.


RESULTS
BSA-bearing coatings had higher mean torque values than did those that bore no protein depot. During the insertion process, less material was lost from the former than from the latter type of coating. The histological and histomorphometric analysis revealed fragments of material to be sheared off from both types of coating at vulnerable points, namely, at the tips of the threads. The sheared-off fragments were retained within the peri-implant space.


CONCLUSIONS
The incorporation of a protein into a biomimetically prepared calcium-phosphate coating increases its resistance to the shear forces that are generated during implant insertion. In a clinical setting, the incorporated protein would be an osteogenic agent, whose osteoinductive potential would not be compromised by the shearing off of coating material, and the osteoconductivity of an exposed implant surface would not be less than that of a coated one.
Hägi
Tobias T
TT
Center of Regenerative Medicine for Skeletal Tissues, Department of Clinical Research, University of Bern, Bern, Switzerland.
Enggist
Lukas
L
Michel
Daniel
D
Ferguson
Stephen J
SJ
Liu
Yuelian
Y
Hunziker
Ernst B
EB
D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D002130:Calcium Phosphates / Q000737:chemistry*; D002417:Cattle; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003757:Dental Implantation / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D008855:Microscopy, Electron, Scanning; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013552:Swine; D019415:Torque
D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D015921:Dental Implants