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British Journal of Medicine and Medical Research, ISSN: 2231-0614,Vol.: 14, Issue.: 4


The Effect of Lithium Disilicate Glass-Ceramic Core Thickness on Fracture Thickness of All-ceramic Restorations


Ezzato 'llah Jalalian1, Amirali Shirian2, Esmat Jafarpour3, Mona Hajighadimi3 and Farin Shamshirgar2*

1Department of Fixed Prosthodontics, Dental Material Research Center, Azad Dental University of Tehran, Iran.

2Department of Prosthodontics, Azad Dental University of Tehran, Iran.

3DDS, Private Practice, Iran.

Article Information
(1) Karl Kingsley, Biomedical Sciences and Director of Student Research University of Nevada, Las Vegas - School of Dental Medicine, USA.
(1) Navroop Kaur Bajwa, Punjab Civil Medical Services, Punjab, India.
(2) Anonymous, Ege Univerity, Turkey.
(3) Vaclav Pouchly, Central European Institute of Technology (CEITEC), Brno University of Technology, Czech Republic.
(4) Anonymous, Federal University of Santa Maria, Brazil.
Complete Peer review History: http://sciencedomain.org/review-history/13645


Statement of the Problem: Fracture strength is fundamental for the long-term success and clinical service of all-ceramic restorations. Core thickness is an important factor affecting fracture strength.

Purpose: The main objective of this study was to assess and compare the fracture strength of 0.4 mm and 0.7 mm core thicknesses.

Materials and Methods: In this in vitro, experimental study, one brass die was prepared with classic chamfer finish line design (0.8 mm depth). An impression was made from the metal die and poured with epoxy resin. The epoxy resin die was scanned and lithium disilicate glass ceramic core was fabricated by the computer-aided design/computer-aided manufacturing (CAD/CAM) technique. IPS e.max cores with 0.4 and 0.7 mm thicknesses were fabricated using CAD/CAM technique. Ten samples were fabricated of each thickness and veneered with IPS e.max. After adhesive bonding onto the die, they were vertically loaded using a universal testing machine until fracture. The data were statistically analyzed using the Kolmogorov-Smirnov test and t-test.

Results: The mean and standard deviation (SD) of fracture strength were 1754±313.47 and 1073±202.81 N, for 0.7 mm and 0.4 mm cores, respectively. The Kolmogorov-Smirnov test showed normal distribution of data; thus, t-test was applied for comparison of the two groups (p<0.001). The fracture strength of 0.7 mm core was significantly greater than that of 0.4 mm core.

Conclusions: Within the limitations of this study, it was concluded that increasing the core thickness improves the fracture strength. However, the mean fracture strength values obtained for 0.4 and 0.7 mm core thicknesses were far greater than the load threshold applied in the oral cavity; thus, both thicknesses can be successfully used in the clinical setting.

Keywords :

IPS e.max; CAD / CAM; core thickness; fracture strength.

Full Article - PDF    Page 1-8

DOI : 10.9734/BJMMR/2016/23493

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