Cargando…
Fractographic analysis of lithium silicate crown failures during sintering
The two-step production process of glass-ceramic dental restorations involves a computer-aided design/computer-aided machining step followed by a crystallization firing for the final material properties to be achieved. Certain firing parameters are believed to trigger spontaneous fracture of crowns...
Autores principales: | , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
SAGE Publications
2019
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6429650/ https://www.ncbi.nlm.nih.gov/pubmed/30915223 http://dx.doi.org/10.1177/2050313X19838962 |
_version_ | 1783405636502945792 |
---|---|
author | Lohbauer, Ulrich Wendler, Michael Rapp, Doreen Belli, Renan |
author_facet | Lohbauer, Ulrich Wendler, Michael Rapp, Doreen Belli, Renan |
author_sort | Lohbauer, Ulrich |
collection | PubMed |
description | The two-step production process of glass-ceramic dental restorations involves a computer-aided design/computer-aided machining step followed by a crystallization firing for the final material properties to be achieved. Certain firing parameters are believed to trigger spontaneous fracture of crowns during the cooling process. In this study, cooling fractures have been reproducibly observed and investigated using fractography combined with material (glass transition temperature) and process (cooling rate) characterization. Stress distribution was visualized using birefringence measurements. Fractographic observations revealed fracture starting at the intaglio side of the crowns specifically at contact points with the support firing pins. Further analysis showed that a fast cooling rate was applied during the glass transition region. Thermal stresses were concentrated around the firing pin supports and released the fracture. To prevent such fractures, a slow cooling protocol below the glass transition temperature is our recommendation to dental technicians. Furthermore, the use of planar firing pad or paste supports is advised over the use of point contact supports. |
format | Online Article Text |
id | pubmed-6429650 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | SAGE Publications |
record_format | MEDLINE/PubMed |
spelling | pubmed-64296502019-03-26 Fractographic analysis of lithium silicate crown failures during sintering Lohbauer, Ulrich Wendler, Michael Rapp, Doreen Belli, Renan SAGE Open Med Case Rep Case Report The two-step production process of glass-ceramic dental restorations involves a computer-aided design/computer-aided machining step followed by a crystallization firing for the final material properties to be achieved. Certain firing parameters are believed to trigger spontaneous fracture of crowns during the cooling process. In this study, cooling fractures have been reproducibly observed and investigated using fractography combined with material (glass transition temperature) and process (cooling rate) characterization. Stress distribution was visualized using birefringence measurements. Fractographic observations revealed fracture starting at the intaglio side of the crowns specifically at contact points with the support firing pins. Further analysis showed that a fast cooling rate was applied during the glass transition region. Thermal stresses were concentrated around the firing pin supports and released the fracture. To prevent such fractures, a slow cooling protocol below the glass transition temperature is our recommendation to dental technicians. Furthermore, the use of planar firing pad or paste supports is advised over the use of point contact supports. SAGE Publications 2019-03-21 /pmc/articles/PMC6429650/ /pubmed/30915223 http://dx.doi.org/10.1177/2050313X19838962 Text en © The Author(s) 2019 http://www.creativecommons.org/licenses/by-nc/4.0/ This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). |
spellingShingle | Case Report Lohbauer, Ulrich Wendler, Michael Rapp, Doreen Belli, Renan Fractographic analysis of lithium silicate crown failures during sintering |
title | Fractographic analysis of lithium silicate crown failures during sintering |
title_full | Fractographic analysis of lithium silicate crown failures during sintering |
title_fullStr | Fractographic analysis of lithium silicate crown failures during sintering |
title_full_unstemmed | Fractographic analysis of lithium silicate crown failures during sintering |
title_short | Fractographic analysis of lithium silicate crown failures during sintering |
title_sort | fractographic analysis of lithium silicate crown failures during sintering |
topic | Case Report |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6429650/ https://www.ncbi.nlm.nih.gov/pubmed/30915223 http://dx.doi.org/10.1177/2050313X19838962 |
work_keys_str_mv | AT lohbauerulrich fractographicanalysisoflithiumsilicatecrownfailuresduringsintering AT wendlermichael fractographicanalysisoflithiumsilicatecrownfailuresduringsintering AT rappdoreen fractographicanalysisoflithiumsilicatecrownfailuresduringsintering AT bellirenan fractographicanalysisoflithiumsilicatecrownfailuresduringsintering |