Biomechanical Strains in Human Bone after Loading Two Implants Designs

Biomechanical Strains in Human Bone after Loading Two Implants Designs
C. ARAG"N, C. MACHADO, J. LEMONS, J.C. BROOME, and D. GIVAN, University of Alabama, Birmingham, USA
March 2004
Clinical Implant Studies
Objectives: In this pilot study, changes in mechanical strains in cadaveric human buccal cortical bone were evaluated for vertical and oblique loading of two implant designs. Methods: Four embalmed partially edentulous mandibles were cleaned and radiographed. A threaded cylindrical 3.8mmx10mm implant with abutment (Nobel Biocare, Yorba Linda, CA) was placed in the posterior region of each mandible and a buccal strain gage was secured 1-2mm from the implant on cortical bone with cyanoacrylate. A constant load of 78.5N was applied in replicates of at least 15 with a stainless steel tip (d=8mm) to the abutment along axial (0¨?) and buccolingual (15¨?) directions. The initial implant was subsequently retrieved and a 4.3mmx10mm tapered implant (Nobel Biocare, Yorba Linda, CA) was placed at the same site and the experiment repeated. Data were recorded and converted to microstrain. Results:Anatomic differences resulted in variability of strain magnitudes between mandibles. However, analysis showed that off-axis loading resulted in higher microstrain for tapered implants. The cylindrical implants showed increased microstrain when loads were changed from 0 to 15¨?, while the tapered implants demonstrated variable changes in buccal strain. Conclusions: Although variability in microstrain was noted amongst different mandibles, as anticipated, the buccal microstrain showed greater magnitude for tapered implants when loaded off-axis and when loads were changed from 0 to 15¨? for the cylindrical implants. (Supported in part by the Academy of Prosthodontics Foundation)