title: Biomechanical evaluation of one-piece and two-piece small-diameter dental implants: In-vitro experimental and three-dimensional finite element analyses.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  Due to the higher peri-implant bone stresses and strains, one-piece implants (NobelDirect) might be not suitable for use as small-diameter implants.
authors.affiliation: Department of Dentistry, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Niao-Sung, Kaohsiung, Taiwan.
authors.forename: Aaron Yu-Jen
authors.initials: AY
authors.lastname: Wu
authors.affiliation: School of Dentistry, China Medical University, Taichung, Taiwan; Department of Bioinformatics and Medical Engineering, Asia University, Wufeng, Taichung, Taiwan.
authors.forename: Jui-Ting
authors.initials: JT
authors.lastname: Hsu
authors.affiliation: Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
authors.forename: Winston
authors.initials: W
authors.lastname: Chee
authors.affiliation: School of Dentistry, China Medical University, Taichung, Taiwan.
authors.forename: Yun-Te
authors.initials: YT
authors.lastname: Lin
authors.affiliation: School of Dentistry, China Medical University, Taichung, Taiwan.
authors.forename: Lih-Jyh
authors.initials: LJ
authors.lastname: Fuh
authors.affiliation: School of Dentistry, China Medical University, Taichung, Taiwan; Department of Bioinformatics and Medical Engineering, Asia University, Wufeng, Taichung, Taiwan. Electronic address: henleyh@gmail.com.
authors.forename: Heng-Li
authors.initials: HL
authors.lastname: Huang
mesh_terms: D001696:Biomechanical Phenomena; D000044:Dental Abutments; D015921:Dental Implants / Q000145:classification*; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008437:Maxilla / Q000000981:diagnostic imaging*; D013314:Stress, Mechanical
chemical_list: D015921:Dental Implants
keywords: dental implant abutment design; dental stress analysis; finite element analysis; strain gauge