Vol. 3 No. 1 (2020): Current Issue
Research Article

Compensation of Polyetherketoneketone Secondary Crowns´' Wear in Combination of Primary Crowns Made of Different Materials: An In-Vitro Study: PEKK Double Crowns Wear

Dörsam I
University of Bonn

Published 2020-11-09


  • Double crowns,
  • Wear,
  • PEKK,
  • Wear compensation


Background: The aim of this study was to investigate the effectiveness of the available methods to compensate the wearing of secondary crowns made from polyetherketoneketone (PEKK).

Methods: Five groups of secondary crowns were investigated. Each group consisted of 10 double crowns. The primary crowns consisted of different dental materials: Gold alloy (group 1), non-precious metal alloy (NPA, group 2), zirconium (group 3), and PEKK (group 4). Group 5 included 10 galvano copings as a reference group. All secondary crowns were made from PEKK. Accordingly, five groups were created: Group 1: Gold/PEKK, Group 2: NPA/PEKK, Group 3: Zirconium/PEKK, Group 4: PEKK/PEKK, and Group 5: PEKK/Galvano/PEKK. Each pair ran through a wear simulator before and after compensation of wearing. The wearing of the samples of the reference group was repaired by galvanisation, for the remaining samples by using Friction-Fit-System (FGP).

Results: After 2,000 cycles, all samples showed constant values before and after wearing compensation. Before wearing compensation, the mean retention forces were: 13.9 N, 19.1 N,  13.3 N, 28.9 N and 4.1 N for gold, NPA, PEKK, zirconium and galvano, respectively. After wearing compensation, the mean retention forces decreased to: 5.1 N, 3.9 N, 3.3 N, and 4.6 N for gold, NPA, PEKK, zirconium, respectively, and increased to 5.5 N for Galvano group.

Conclusions: It can be concluded that post galvanisation still seems to be the proper possible method to ompensate the loss of friction of the double crowns.