title: Laboratory study on abutment movement of the combined clasp, the extension clasp and the telescopic crown.
abstract: OBJECTIVE
  To study the influence of three kinds of retainers on the abutment movement of removable partial dentures (RPDs) for restoring the dentition with unilateral distal-extended tooth missing.
  
  
  METHODS
  The combined clasp, the extension clasp and the telescopic crown were designed to retain RPDs. When food chip was masticated between dentitions, the displacement of abutments was measured by a high-sensitive-laser-transferring-detector, and then the data was statistically analyzed.
  
  
  RESULTS
  All of abutments showed the inclination, torsion and vertical translocation. Of them, abutments with telescopic crowns had the lowest horizontal torsion (P < 0.01) and the highest vertical translocation (P < 0.01).
  
  
  CONCLUSIONS
  Compared with the combined clasp and the extension clasp, the telescopic crowns enable abutments to bear the load more axial and the stress to be distributed more even, so the design of the telescopic crown may be considered more favourable for the health of abutments.
authors.affiliation: Department of Prosthodontics, Oral College of Tongji University, Shanghai 200072, China.
authors.forename: Dongwei
authors.initials: D
authors.lastname: Han
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Qiaoming
authors.initials: Q
authors.lastname: Li
authors.forename: Binghong
authors.initials: B
authors.lastname: Li
mesh_terms: D003442:Crowns; D000044:Dental Abutments; D016734:Dental Clasps; D003799:Dental Stress Analysis / Q000379:methods; D003781:Denture Retention / Q000295:instrumentation / Q000379:methods; D003832:Denture, Partial, Removable; D006801:Humans; D014087:Tooth Movement Techniques