J Adv Prosthodont.  2017 Aug;9(4):252-256. 10.4047/jap.2017.9.4.252.

Ceramic molar crown reproducibility by digital workflow manufacturing: An in vitro study

• Jeong ID
• Kim WC
• Park J
• Kim CM
• Kim JH

• KMID: 2398071
• DOI: http://doi.org/10.4047/jap.2017.9.4.252

Abstract

PURPOSE
This in vitro study aimed to analyze and compare the reproducibility of zirconia and lithium disilicate crowns manufactured by digital workflow.
MATERIALS AND METHODS
A typodont model with a prepped upper first molar was set in a phantom head, and a digital impression was obtained with a video intraoral scanner (CEREC Omnicam; Sirona GmbH), from which a single crown was designed and manufactured with CAD/CAM into a zirconia crown and lithium disilicate crown (n=12). Reproducibility of each crown was quantitatively retrieved by superimposing the digitized data of the crown in 3D inspection software, and differences were graphically mapped in color. Areas with large differences were analyzed with digital microscopy. Mean quadratic deviations (RMS) quantitatively obtained from each ceramic group were statistically analyzed with Student's t-test (α=.05).
RESULTS
The RMS value of lithium disilicate crown was 29.2 (4.1) µm and 17.6 (5.5) µm on the outer and inner surfaces, respectively, whereas these values were 18.6 (2.0) µm and 20.6 (5.1) µm for the zirconia crown. Reproducibility of zirconia and lithium disilicate crowns had a statistically significant difference only on the outer surface (P<.001). The outer surface of lithium disilicate crown showed over-contouring on the buccal surface and under-contouring on the inner occlusal surface. The outer surface of zirconia crown showed both over- and under-contouring on the buccal surface, and the inner surface showed under-contouring in the marginal areas.
CONCLUSION
Restoration manufacturing by digital workflow will enhance the reproducibility of zirconia single crowns more than that of lithium disilicate single crowns.

Keyword

Digital workflow manufacturing; Ceramic crown reproducibility; Lithium disilicate; Zirconia

MeSH Terms

Ceramics*
Crowns*
Head
In Vitro Techniques*
Lithium
Microscopy
Molar*
Lithium

Figure

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  Fig. 1 Color-coded difference images for qualitative reproducibility deviation analysis of inner and outer surfaces.

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  Fig. 2 Digital microscope images of outer and inner surfaces of zirconia and lithium disilicate crowns (blue arrows indicate most significantly different areas in color-coded difference images of Fig. 1).

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