Statement of problem: The use of short dental implants is usually confined to areas of
the mouth with limited vertical bone height. As a result, longer implant crowns are
required to restore the occlusion with the opposing arch, leading to a disproportionate
crown-to-implant ratio (C/I ratio).
Purpose: The purpose of this study was to evaluate the stress distribution patterns on
crestal bone of short implants plateau-designed connected with different crown heights,
and to compare these findings with those of regular implants.
Material and Methods: Two implant designs (∅5 mm×6 mm and ∅5 mm×11 mm) and
abutments (∅5 mm×9 mm and ∅5 mm×5 mm) were scanned using a micro-CT scanner.
STL surface models were subsequently extracted to generate surfaces. All models were
imported to Abaqus CAE for three-dimensional non-linear finite element analysis. For
each implant model, loadings of 100, 200, and 700 N were simulated in 2 directions: pure
vertical and at an oblique angle of 15 degrees.
Results: At 100 and 200 N oblique loads, peak compressive and tensile stresses ranged
from 18.30 to 53.57 MPa and 7.39 to 43.95 MPa, respectively. At 700 N oblique loads,
the ∅5 mm×6 mm implant with long abutment model exceeded the compressive and
tensile strength of cortical bone, at 193.4 and 158.6 MPa correspondingly. For 700 N
oblique loads, increasing crown height increased peak compressive stress by 28.6 % and
peak tensile stress by 28.4 %. Stress distribution patterns showed the highest amounts of
stress located at the implant crest module in cortical bone.
Conclusion: Stress distribution patterns for the oblique loads of 100 and 200 N were
similar in all models, regardless of the C/I ratios. All peak stresses were within
physiological tolerance. At 700 N loads, increasing crown height resulted in bone failure.
University of Minnesota M.S. thesis. December 2010. Major: Dentistry. Advisor: Alex S. L. Fok, PhD. 1 computer file (PDF); vii, 47 pages.
Evaluation of stress distribution patterns on short implants with differing crown heights: a three dimensional finite element analysis.
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