title: In vitro comparison of implant- versus gingiva-supported removable dentures in anterior and posterior applications.
abstract: OBJECTIVE
  Removable dentures with different denture teeth may provide different performance and resistance in implant and gingival situations, or anterior and posterior applications.
  
  
  METHODS
  Two situations of removable dentures were investigated: gingiva (flexible) and implant (rigid) bearing. For simulating the gingiva/jaw situation, the dentures were supported with flexible lining material. For the implant situation, implants (d = 4.1 mm) were screwed into polymethylenmethacrylate (PMMA) resin. Two commercial (Vita-Physiodens MRP, SR Vivodent/Orthotyp DCL) and two experimental materials (EXP1, EXP2) were investigated in anterior (A) and posterior (P) tooth locations. Chewing simulation was performed, and failures were analyzed (microscopy, SEM). Fracture strength of surviving dentures was determined.
  
  
  RESULTS
  Only EXP1 revealed failures during chewing simulation. Failures varied between anterior and posterior locations, and between implant (P:4x; A:7x) or gingiva (P:1x; A:2x) situations. Kaplan-Meier log-rank test revealed significant differences for implant situations (p < 0.002), but not for gingiva bearing (p > 0.093). Fracture testing in the implant situation provided significantly highest values for EXP2 (1476.4 ± 532.2 N) in posterior location, and for DCL (1575.4 ± 264.4 N) and EXP2 (1797.0 ± 604.2 N) in anterior location. For gingival bearing, significantly highest values were found for DCL/P (2148.3 ± 836.3 N), and significantly lowest results for EXP1/A (308.2 ± 115.6 N). For EXP1 + EXP2 + Vita/P and for EXP1/A no significant differences were found between implant- or gingiva-supported situations.
  
  
  CONCLUSIONS
  Anterior and posterior teeth showed different material-dependent in vitro performance, further influenced by implant/gingiva bearing. While an implant in anterior application increased fracture strength of two materials, it decreased fracture values of 3/4 of the materials in posterior application.
  
  
  CONCLUSIONS
  Survival of denture teeth may be influenced by material, oral position, and bearing situation.
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rosentritt
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Heidtkamp
authors.affiliation: Department of Orthodontics, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Hösl
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hahnel
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany. verena.preis@ukr.de.
authors.forename: Verena
authors.initials: V
authors.lastname: Preis
mesh_terms: D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003779:Denture Design; D003822:Denture Liners; D003829:Denture, Partial; D005881:Gingiva; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019904:Polymethyl Methacrylate; D013499:Surface Properties
chemical_list: D019904:Polymethyl Methacrylate
keywords: Anterior/posterior teeth; Chewing simulation; Denture teeth; Fracture resistance; Implant/gingiva bearing