title: Effect of direct retainer and major connector designs on RPD and abutment tooth movement dynamics.
abstract: Designs of removable partial dentures are suggested to affect the mobility of abutment teeth and removable partial denture (RPD) during oral functions. This study aimed to examine the effect of direct retainer and major connector designs on RPD dynamics under simulated loading. Six different Kennedy class II maxillary RPDs were fabricated on a maxillary model. These dentures involved 3 different direct retainers (wrought-wire clasp, RPA clasp, and conical crown telescopic retainer) and 2 different major connectors (Co-Cr major connector and heat-cured acrylic resin with a metal strengthener). Using an experimental model with simulated periodontal ligaments and mucosa that were fabricated using silicone impression material, three-dimensional displacements of the RPDs were measured under a simulated 30-N loading with a displacement transducer type M-3. Significant effects of "direct retainer design" on bucco-palatal displacements and "major connector" on mesio-distal displacements were revealed by 2 x 3 two-way analysis of variance of abutment teeth movements (P < 0.001 and P = 0.002, respectively). Additionally, analysis of variance of RPD displacements revealed significant effects of "direct retainer design" on corono-apical displacements and "major connector" on mesio-distal displacements (P = 0.001 and P = 0.028, respectively). Rigid direct retainers and rigid major connectors decrease the movements of both abutment tooth and RPD.
authors.affiliation: Removable Partial Denture Prosthodontics, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. haruka.rpro@tmd.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Itoh
authors.forename: K
authors.initials: K
authors.lastname: Baba
authors.forename: K
authors.initials: K
authors.lastname: Aridome
authors.forename: D
authors.initials: D
authors.lastname: Okada
authors.forename: A
authors.initials: A
authors.lastname: Tokuda
authors.forename: A
authors.initials: A
authors.lastname: Nishiyama
authors.forename: H
authors.initials: H
authors.lastname: Miura
authors.forename: Y
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D000044:Dental Abutments; D016734:Dental Clasps; D003799:Dental Stress Analysis; D003779:Denture Design; D003781:Denture Retention / Q000295:instrumentation*; D003832:Denture, Partial, Removable; D006801:Humans; D008437:Maxilla; D008953:Models, Anatomic; D013314:Stress, Mechanical