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Microstructural Observations of Laser-Sintered Specimens for Prosthodontic Applications

Fathalah , Ahmed A.A
http://rave.ohiolink.edu/etdc/view?acc_num=osu1366286613

Abstract Details

2013, Master of Science, Ohio State University, Dentistry.
ABSTRACT Objectives: Laser sintering is a recently introduced technology that has been used to prepare dental restorations from a biocompatible Co-Cr base metal alloy. The objectives of this study were to obtain detailed information about dimensional accuracy available with laser sintering, along with the microstructure and Vickers hardness of the alloy. Methods: Representative maxillary coping and implant framework specimens were prepared from STL files by a commercial laser sintering apparatus (Phenix Systems), using the dedicated Co-Cr alloy. Compatible dental porcelain was bonded to the coping specimen (North Shore Dental Labs, Lynn, MA). Specimens were sectioned with a slow-speed diamond saw, prepared for metallographic examination by resin-mounting and polishing with a series of abrasives, and observed with a scanning electron microscope and optical microscope at a range of magnifications. Alloy compositions were obtained by x-ray energy-dispersive spectrometric analyses. A Co-Cr alloy implant framework prepared by conventional milling/polishing and a cast Ni-Cr alloy coping for a conventional metal-ceramic restoration with the dental porcelain served as controls. Microstructures of the laser-sintered and cast alloys were revealed by electrolytic etching. Values of Vickers hardness for the Co-Cr alloy in the laser-sintered implant framework and the coping for the metal-ceramic restoration were compared, along with the cast coping. Dimensions of the milled/polished and laser-sintered implant frameworks were measured microscopically and compared. Results: The laser-sintered Co-Cr alloy had a fine-grained microstructure, and there was some difficulty in revealing full details by electrolytic etching, whereas the cast Ni-Cr alloy had a well-defined dendritic microstructure. The laser-sintered Co-Co alloy coping had intimate interfacial attachment to dental porcelain. The Vickers hardness was slightly (< 10%, but statistically significant), higher for the laser-sintered Co-Cr implant framework, compared to the laser-sintered Co-Cr coping. The laser-sintered Co-Cr alloy was twice as hard as the cast Ni-Cr alloy. Fits on the original cast/die of the implant frameworks and metal-ceramic specimens were judged to be clinically acceptable by two prosthodontists. Dimensions of the laser-sintered and milled/polished implant frameworks were in excellent agreement for well-defined measurement locations. Conclusions: The fine-grained laser-sintered Co-Cr alloy should have high values of strength, indicated by the high measured Vickers hardness. More research is needed for the electrolytic etching process to reveal the laser-sintered microstructure in greater detail. Use of a nanoindenter is recommended to provide further information about any local hardness variations in the microstructure. The laser-sintering process produces representative prostheses with clinically acceptable accuracy, in agreement with previous publications from other research groups.
William A. Brantley, PhD (Advisor)
45 p.
Dentistry
Laser sintering; Alloys; Prosthodontics; Hardness; Composition; Metals; Structure

Recommended Citations

Citations

  • Fathalah , A. A.A. (2013). Microstructural Observations of Laser-Sintered Specimens for Prosthodontic Applications [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366286613

    APA Style (7th edition)

  • Fathalah , Ahmed. Microstructural Observations of Laser-Sintered Specimens for Prosthodontic Applications. 2013. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1366286613.

    MLA Style (8th edition)

  • Fathalah , Ahmed. "Microstructural Observations of Laser-Sintered Specimens for Prosthodontic Applications." Master's thesis, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366286613

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.