Journal Article Biomechanical effects of offset placement of dental implants in the edentulous posterior mandible

SHIMURA Yuta  ,  SATO Yuji  ,  KITAGAWA Noboru  ,  OMORI Miyuki

2 ( 1 )  , p.17 , 2016-12 , Springer
Background: Proper implant placement is very important for long-term implant stability. Recently, numerousbiomechanical studies have been conducted to clarify the relationship between implant placement and peri-implantstress. The placement of multiple implants in the edentulous posterior mandible has been studied by geometricanalysis, three-dimensional finite element analysis (FEA), model experimentation, etc. Offset placement is a techniquethat reduces peri-implant load. However, few studies have used multiple analyses to clarify the value of the offsetplacement under identical conditions.The present study aimed to clarify the biomechanical effects of offset placement on the peri-implant bone in edentulousposterior mandibles by comparative investigation using FEA and model experimentation with strain gauges.Methods: Three implants were embedded in an artificial mandible in the parts corresponding to the first premolar, thesecond premolar, and the first molar. A titanium superstructure was mounted to prepare models (experimental models).Three load points (buccal, central, and lingual) were established on the part of the superstructure corresponding to thefirst molar. Three types of experimental models, each with a different implant placement, were prepared. In one model,the implants were placed in a straight line; in the other two, the implants in the parts corresponding to the secondpremolar and the first molar were offset each by a 1-mm increment to the buccal or lingual side. Four strain gauges wereapplied to the peri-implant bone corresponding to the first molar.The experimental models were imaged by micro-computed tomography (CT), and FEA models were constructed fromthe CT data. A vertical load of 100 N was applied on the three load points in the experimental models and in the FEAmodels. The extent of compressed displacement and the strain in the peri-implant bone were compared between theexperimental models and the FEA models.Results: Both experimental and FEA models suffered the least compressed displacement during central loading in allplacements. The greatest stress and compressive strain was on the load side in all types of placements.Conclusions: Offset placement may not necessarily be more biomechanically effective than straight placement inedentulous posterior mandibles.

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