Influence of specimens’ geometry and materials on the thermal stresses in dental restorative materials during thermal cycling

D. Fabris, J.C.M. Souza, F.S. Silva, M. Fredel, Michael Gasik, Bruno Henriques

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)

Abstract

Objectives

Thermal cycling is widely used to simulate the aging of restorative materials corresponding to the changes of temperature in the oral cavity. However, test parameters present in literature vary considerably, which prevents comparison between different reports. The aim of this work is to assess the influence of the specimens’ geometry and materials on the thermal stresses developed during thermal cycling tests.

Materials and methods

Finite elements method was used to simulate the conditions of thermal cycling tests for three different sample geometries: a three-points bending test sample, a cylinder rod and more complex shape of a restoration crown. Two different restorative systems were considered: all-ceramic (zirconia coupled with porcelain) and metal-ceramic (CoCrMo alloy coupled with porcelain). The stress state of each sample was evaluated throughout the test cycle.

Results

The results show that the sample geometry has great influence on the stress state, with difference of up to 230% in the maximum stress between samples of the same composition. The location of maximum stress also changed from the interface between materials to the external wall.

Conclusions

Maximum absolute stress values were found to vary between 2 and 4 MPa, which might not be critical even for ceramics. During multi-cycle testing these stresses would cause different fatigue in various locations. The zirconia-based specimens and zirconia-based restoration (crown) exhibited the most similar stress states. Thus it might be recommended to use these geometries for fast screening of the materials for this type of restorations.

Clinical significance

The selection of specimens’ geometry and materials should be carefully considered when aging conditions close to clinical ones want to be simulated.
Original languageEnglish
Pages (from-to)41-48
Number of pages8
JournalJOURNAL OF DENTISTRY
Volume69
Early online date2017
DOIs
Publication statusPublished - Feb 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • Thermalcycling
  • Thermal stresses
  • Metal-ceramic restorations
  • All-ceramic restorations

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