title: Retention forces of 14-unit zirconia telescopic prostheses with six double crowns made from zirconia--an in vitro study.
abstract: OBJECTIVE
  The aim of this study was to evaluate the retention forces (RFs) of zirconia double-crown systems, with primary and secondary crowns made from zirconia in vitro.
  
  
  METHODS
  Ten maxillary models with six abutment teeth were prepared. Sixty inner crowns were fabricated from pre-sintered zirconia with a taper of 0°. Ten 14-unit telescopic prostheses (removable partial dentures, RDPs) were fabricated, using the same computer-aided design/computer-aided manufacturing system as that used for the inner crowns. The removal test was performed in a standardized setup using a universal testing device at a crosshead speed of 10 mm/min. Ten separation cycles were carried out for each single primary crown as well as for each 14-unit RDP in the presence of artificial saliva. The results were imported into a statistic program and analysed by a one-way ANOVA and post hoc tests. The level of significance was set at 5 %.
  
  
  RESULTS
  The mean RFs of the single double-crown systems were in the range of 0.611-2.895 N, whereas the RFs for the whole RDP varied between 8.1 and 13.6 N. RF was dependent on the abutment tooth (p < 0.001) and on the model (p < 0.001).
  
  
  CONCLUSIONS
  The results of this study indicate that the manufacturing of full-zirconia double-crown systems is possible as well as reproducible. The RFs are comparable to those reported from casted and electroformed double-crown systems.
  
  
  CONCLUSIONS
  It has been shown that the RFs of the presented telescopic system are comparable to existing double-crown systems.
authors: Department of Prosthodontics, Ludwig-Maximilians University, Goethestraße 70, 80336, Munich, Germany.
authors: Julian
authors: J
authors: Groesser
authors: Department of Prosthodontics, Ludwig-Maximilians University, Goethestraße 70, 80336, Munich, Germany.
authors: Caroline
authors: C
authors: Sachs
authors: Department of Prosthodontics, Ludwig-Maximilians University, Goethestraße 70, 80336, Munich, Germany.
authors: Philipp
authors: P
authors: Heiß
authors: Stadelmann Dental, Fraunhoferstraße 30, 80469, Munich, Germany.
authors: Markus
authors: M
authors: Stadelmann
authors: Department of Prosthodontics, Ludwig-Maximilians University, Goethestraße 70, 80336, Munich, Germany.
authors: Kurt
authors: K
authors: Erdelt
authors: Department of Prosthodontics, Ludwig-Maximilians University, Goethestraße 70, 80336, Munich, Germany. florian.beuer@med.uni-muenchen.de.
authors: Florian
authors: F
authors: Beuer
mesh_terms: D003442:Crowns; D017266:Dental Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D015040:Zirconium
chemical_list: D015040:Zirconium
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