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Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co-Cr dental alloys.
Dent Mater. 2015 Dec; 31(12):e306-15.DM

Abstract

OBJECTIVE

The objective of this study was to identify the different microstructures produced by CC, PM and as-cast techniques for Co-Cr alloys and their phase stability following porcelain firings.

METHODS

Three bi-layer porcelain veneered Co-Cr specimens and one monolithic Co-Cr specimen of each alloy group [cast, powder metallurgy (PM), CAD/CAM (CC)] were manufactured and analyzed using electron backscatter diffraction (EBSD), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Specimens were treated to incremental numbers of porcelain firings (control 0, 5, 15) with crystallographic data, grain size and chemical composition subsequently obtained and analyzed.

RESULTS

EBSD datasets of the cast alloy indicated large grains >200 μm whereas PM and CC alloy consisted of mean arithmetic grain sizes of 29.6 μm and 19.2 μm respectively. XRD and EBSD results both indicated the highest increase in hcp content (>13vol%) for cast Co-Cr alloy after treatment with porcelain firing while PM and CC indicated <2vol% hcp content. A fine grain interfacial layer developed on all surfaces of the alloy after porcelain firing. The depth of this layer increased with porcelain firings for as-cast and PM but no significant increase (p>.05) was observed in CC. EDS line scans indicated an increase in Cr content at the alloy surface after porcelain firing treatment for all three alloys.

SIGNIFICANCE

PM and CC produced alloy had superior fcc phase stability after porcelain firings compared to a traditional cast alloy. It is recommended that PM and CC alloys be used for porcelain-fused-to-metal restorations.

Authors+Show Affiliations

Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand. Electronic address: lika6144@gmail.com.Department of Geology, University of Otago, Dunedin, New Zealand.Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand.Biomaterials Laboratory, Faculty of Dentistry, University of Sydney, Sydney, Australia.

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

26597769

Citation

Li, Kai Chun, et al. "Comparison of the Microstructure and Phase Stability of As-cast, CAD/CAM and Powder Metallurgy Manufactured Co-Cr Dental Alloys." Dental Materials : Official Publication of the Academy of Dental Materials, vol. 31, no. 12, 2015, pp. e306-15.
Li KC, Prior DJ, Waddell JN, et al. Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co-Cr dental alloys. Dent Mater. 2015;31(12):e306-15.
Li, K. C., Prior, D. J., Waddell, J. N., & Swain, M. V. (2015). Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co-Cr dental alloys. Dental Materials : Official Publication of the Academy of Dental Materials, 31(12), e306-15. https://doi.org/10.1016/j.dental.2015.10.010
Li KC, et al. Comparison of the Microstructure and Phase Stability of As-cast, CAD/CAM and Powder Metallurgy Manufactured Co-Cr Dental Alloys. Dent Mater. 2015;31(12):e306-15. PubMed PMID: 26597769.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co-Cr dental alloys. AU - Li,Kai Chun, AU - Prior,David J, AU - Waddell,J Neil, AU - Swain,Michael V, Y1 - 2015/11/17/ PY - 2014/11/25/received PY - 2014/12/24/revised PY - 2015/10/22/accepted PY - 2015/11/25/entrez PY - 2015/11/26/pubmed PY - 2017/5/16/medline KW - CAD/CAM KW - Co–Cr alloy KW - Crystal structure KW - EBSD KW - Electron backscatter diffraction KW - Metal–porcelain interface KW - Phase stability KW - Powder metallurgy SP - e306 EP - 15 JF - Dental materials : official publication of the Academy of Dental Materials JO - Dent Mater VL - 31 IS - 12 N2 - OBJECTIVE: The objective of this study was to identify the different microstructures produced by CC, PM and as-cast techniques for Co-Cr alloys and their phase stability following porcelain firings. METHODS: Three bi-layer porcelain veneered Co-Cr specimens and one monolithic Co-Cr specimen of each alloy group [cast, powder metallurgy (PM), CAD/CAM (CC)] were manufactured and analyzed using electron backscatter diffraction (EBSD), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Specimens were treated to incremental numbers of porcelain firings (control 0, 5, 15) with crystallographic data, grain size and chemical composition subsequently obtained and analyzed. RESULTS: EBSD datasets of the cast alloy indicated large grains >200 μm whereas PM and CC alloy consisted of mean arithmetic grain sizes of 29.6 μm and 19.2 μm respectively. XRD and EBSD results both indicated the highest increase in hcp content (>13vol%) for cast Co-Cr alloy after treatment with porcelain firing while PM and CC indicated <2vol% hcp content. A fine grain interfacial layer developed on all surfaces of the alloy after porcelain firing. The depth of this layer increased with porcelain firings for as-cast and PM but no significant increase (p>.05) was observed in CC. EDS line scans indicated an increase in Cr content at the alloy surface after porcelain firing treatment for all three alloys. SIGNIFICANCE: PM and CC produced alloy had superior fcc phase stability after porcelain firings compared to a traditional cast alloy. It is recommended that PM and CC alloys be used for porcelain-fused-to-metal restorations. SN - 1879-0097 UR - https://www.unboundmedicine.com/medline/citation/26597769/Comparison_of_the_microstructure_and_phase_stability_of_as_cast_CAD/CAM_and_powder_metallurgy_manufactured_Co_Cr_dental_alloys_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0109-5641(15)00440-6 DB - PRIME DP - Unbound Medicine ER -