J Adv Prosthodont.  2016 Apr;8(2):137-143. 10.4047/jap.2016.8.2.137.

Effect of different grinding burs on the physical properties of zirconia

• Lee KR
• Choe HC
• Heo YR
• Lee JJ
• Son MK

• KMID: 2176655
• DOI: http://doi.org/10.4047/jap.2016.8.2.137

Abstract

PURPOSE
Grinding with less stress on 3Y-TZP through proper selection of methods and instruments can lead to a long-term success of prosthesis. The purpose of this study was to compare the phase transformation and physical properties after zirconia surface grinding with 3 different grinding burs.
MATERIALS AND METHODS
Forty disc-shaped zirconia specimens were fabricated. Each Ten specimens were ground with AllCeramic SuperMax (NTI, Kahla, Germany), Dura-Green DIA (Shofu Inc., Kyoto, Japan), and Dura-Green (Shofu Inc., Kyoto, Japan). Ten specimens were not ground and used as a control group. After the specimen grinding, XRD analysis, surface roughness test, FE-SEM imaging, and biaxial flexural strength test were performed.
RESULTS
After surface grinding, small amount of monoclinic phase in all experimental groups was observed. The phase change was higher in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs. The roughness of surfaces increased in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs than control groups and ground with Dura-Green. All experimental groups showed lower flexural strength than control group, but there was no statistically significant difference between control group and ground with Dura-Green DIA and AllCeramic SuperMax burs. The specimens, which were ground with Dura- Green showed the lowest strength.
CONCLUSION
The use of dedicated zirconia-specific grinding burs such as Dura-Green DIA and AllCeramic SuperMax burs decreases the grinding time and did not significantly affect the flexural strength of zirconia, and therefore, they may be recommended. However, a fine polishing process should be accompanied to reduce the surface roughness after grinding.

Keyword

3Y-TZP; Phase transformation; XRD; Roughness; Biaxial flexural strength

MeSH Terms

Prostheses and Implants

Figure

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  Fig. 1 Grinding burs used in this study. (A) NTI® AllCeramic SuperMax, (B) Shofu Dura-Green DIA, (C) Shofu Dura-Green.

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  Fig. 2 Biaxial flexural strength testing apparatus: ISO Standard 6872 for dental ceramic.

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  Fig. 3 FE-SEM images of bur surface (×1000) after specimen grinding. (A) NTI® AllCeramic SuperMax, (B) Shofu Dura-Green DIA, (C) Shofu Dura-Green. The arrow points indicate diamond grit.

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  Fig. 4 FE-SEM images of the specimen surface (×1000). (A) Group A, (B) Group B, (C) Group C, (D) Control Group. Group C showed smaller scratch grooves and a smoother surface, compared to Groups A and B.

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  Fig. 5 FE-SEM images of the fracture surface in experimental group specimen after flexural strength test. The arrow points indicate crack line.

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