Characterization of internal structural integrity of all-ceramic crowns using micro-computed tomography
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Abstract
Different material and fabrication technique might affect the flaw distribution in a dental restoration. The objectives of this study were to quantify the percentage volume of the existing flaws in an all-ceramic posterior restoration fabricated by heat-pressing and computer-aided design and computer-aided manufacturing (CAD-CAM) techniques.
Materials and methods: Three lithia-disilicate-based dental ceramics were used in this study (VINTAGE LD Press, IPS e.max Press and IPS e.max CAD). Ten upper first molar crowns were made for VINTAGE LD Press and IPS e.max Press as monolithic crowns using a heat-pressing technique. Ten posterior crowns were made for IPS e.max CAD using a CAD-CAM technique. Ten upper first molar substructures were also made using IPS e.max CAD and veneered with IPS e.max Ceram using a conventional condensation and sintering technique, as a control group. Micro-computed tomography (micro-CT) was used to analyze internal defects within each ceramic crown using image pixel size of 9.16 micron and a power voltage of 80 kV. The statistically significant differences between the mean percentages of closed pore for all experimental groups were analyzed using Kruskal-Wallis nonparametric test at a significance level of .05.
Results: The quantity of existing pores in an all-ceramic posterior crown was ranged between 0.0018 to 0.0482 % and Vintage LD Press and IPS e.max® CAD veneered with IPS e.max® Ceram had the highest numbers of pore compared with other monolithic restorations. All the internal pores were randomly distributed with the sizes of 36.6-256 µm.
Conclusion: The results from this study indicated that processing technique and manufacturer had an effect on the quantity and size of internal pores observed in all-ceramic restorations.
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References
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