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Updated: Mar 23, 2026
An Improved Mechanical Testing Method to Assess Bone-implant Anchorage
Published on: February 10, 2014
Biomechanical evaluation of one-piece and two-piece small-diameter dental implants: In-vitro experimental and
Aaron Yu-Jen Wu1, Jui-Ting Hsu2, Winston Chee3
1Department of Dentistry, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Niao-Sung, Kaohsiung, Taiwan.
Background/Purpose:
Small-diameter dental implants are associated with a higher risk of implant failure. This study used both three-dimensional finite-element (FE) simulations and in-vitro experimental tests to analyze the stresses and strains in both the implant and the surrounding bone when using one-piece (NobelDirect) and two-piece (NobelReplace) small-diameter implants, with the aim of understanding the underlying biomechanical mechanisms.
Methods:
Six experimental artificial jawbone models and two FE models were prepared for one-piece and two-piece 3.5-mm diameter implants. Rosette strain gauges were used for in-vitro tests, with peak values of the principal bone strain recorded with a data acquisition system. Implant stability as quantified by Periotest values (PTV) were also recorded for both types of implants. Experimental data were analyzed statistically using Wilcoxon's rank-sum test. In FE simulations, the peak value and distribution of von-Mises stresses in the implant and bone were selected for evaluation.
Results:
In in-vitro tests, the peak bone strain was 42% lower for two-piece implants than for one-piece implants. The PTV was slightly lower for one-piece implants (PTV = -6) than for two-piece implants (PTV = -5). In FE simulations, the stresses in the bone and implant were about 23% higher and 12% lower, respectively, for one-piece implants than those for two-piece implants.
Conclusion:
Due to the higher peri-implant bone stresses and strains, one-piece implants (NobelDirect) might be not suitable for use as small-diameter implants.
