title: Retainer design for unilateral extension base partial removable dental prosthesis by three-dimensional finite element analysis.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of differences in the retainer design on load on abutment teeth and displacement of the denture base in mandibular unilateral extension base partial removable dental prosthesis to determine the optimum design for a mechanically appropriate retainer.
  
  
  METHODS
  Three models were used. Each incorporating a removable denture with different designs of retainer positioned. In design A, Akers clasps were positioned over the first and second premolars. In design B, embrasure clasp was positioned over the first and second premolars. In design C, rest and back-action clasps were positioned over the first and second premolars, respectively. Loading on the occlusal surface of the dentures was performed in the vertical, oblique lingual and buccal directions. Load on the abutment teeth and displacement of the denture base were determined by the three-dimensional finite element method analysis.
  
  
  RESULTS
  Vertical and buccolingual load on the abutment teeth by lingual and buccal direction loading on the denture were smaller in designs B and C than in design A. However, the superioinferior and buccolingual displacement of the denture base by buccal direction loading on the denture were largest in design A. Superioinferior and buccolingual displacement of the denture base by the lingual direction loading on the denture were largest in design C.
  
  
  CONCLUSIONS
  Under the conditions set in this study, the stability of design A was greater than that of design B or C, but load on the abutment teeth was larger.
authors.affiliation: Department of Removable Prosthodontics and Gerodontology, Tokyo Dental College, Chiba City, Chiba, Japan. info@smile-dental-clinic.com
authors.forename: Koichi
authors.initials: K
authors.lastname: Aoda
authors.forename: Ichiro
authors.initials: I
authors.lastname: Shimamura
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tahara
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sakurai
mesh_terms: D001696:Biomechanical Phenomena; D000044:Dental Abutments; D003779:Denture Design; D003781:Denture Retention / Q000295:instrumentation*; D003832:Denture, Partial, Removable; D006801:Humans