title: Telescopic magnetic attachment for implant-supported denture: evaluation of splint effect.
abstract: OBJECTIVE
  Retrievability, connecting strength, and ease of laboratory work are important but conflicting prerequisites for the success of an implant superstructure, particularly with regard to immediate function. To resolve this issue, a telescopic magnetic attachment system has been developed for implant-supported removable dentures. The splinting effect of the attachment was evaluated for stress distribution and elevation with an in vitro model of three implants in an edentulous mandible.
  
  
  METHODS
  Two types of telescopic magnetic attachments were prepared; the inclination angles of the axial wall of the abutment were 2.5 and 6.0 degrees. Three types of three-unit superstructures--a screw-retained superstructure and two telescopic magnet-retained superstructures--were fabricated. Static loads of 24.5, 49, and 98 N were applied vertically at three loading points on one side of each occlusal table. The elevation was measured as the height at which the magnet-retained superstructure detached from the abutment (on the other side of the prosthesis). In addition, by means of strain gauges, the stress distribution around the implants was evaluated and compared among the superstructures with the same three loads applied at six different points.
  
  
  RESULTS
  The magnet-retained superstructure with the axial wall inclined at 2.5 degrees did not detach from the abutment. The differences in stress distribution between the screw-retained and magnet-retained superstructures with a 2.5-degree inclination were found to be statistically insignificant. The magnet-retained superstructure with a 6-degree inclination detached from the abutment, and the stress was concentrated during loading to a cantilever site.
  
  
  CONCLUSIONS
  Because of its stress distribution and elevation, the new telescopic magnetic attachment, which has properties such as splinting the implants, ease of fabrication, and retrievability, is expected to be a viable alternative for the retention of implant-supported removable dentures.
authors.affiliation: Department of Prosthodontics, Tonji University, Shanghai, China.
authors.forename: JianRong
authors.initials: J
authors.lastname: Chen
authors.forename: Yoritoki
authors.initials: Y
authors.lastname: Tomotake
authors.forename: Megumi
authors.initials: M
authors.lastname: Watanabe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ishida
authors.forename: Kan
authors.initials: K
authors.lastname: Nagao
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ichikawa
mesh_terms: D000044:Dental Abutments; D016734:Dental Clasps; D003758:Dental Implantation, Endosseous / Q000295:instrumentation* / Q000379:methods; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D003781:Denture Retention / Q000295:instrumentation*; D006801:Humans; D008280:Magnetics; D008334:Mandible; D008422:Materials Testing; D003765:Models, Dental; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D015921:Dental Implants