Banner Portal
Fracture toughness of three heat pressed ceramic systems


Dental porcelain. Hardness tests. Elastic modulus.

How to Cite

Fiorin L, Theodoro GT, Moris ICM, Rodrigues RCS, Ribeiro RF, Faria ACL. Fracture toughness of three heat pressed ceramic systems. Braz. J. Oral Sci. [Internet]. 2018 Apr. 3 [cited 2024 Feb. 29];17:e18017. Available from:


Aim: The aim of this study was to evaluate fracture toughness by indentation method of three dental ceramics processed by heat pressing. The ceramics evaluated were fluorapatite glass ceramic (ZIR), glass ceramic containing leucite (POM) and leucite-reinforced glass ceramic (EMP). Materials and methods: Ninety disks (13mm of diameter x 4mm of thickness) and nine rectangular specimens (25x4x2mm) were made to evaluate, respectively, microhardness/fracture toughness (n=30) and elastic modulus (n=3). Samples were obtained by pressing ceramic into refractory molds. After polishing, Vickers microhardness was evaluated under 4,904N load for 20s. Elastic modulus was measured by impulse excitation technique. Data from microhardness and elastic modulus were used to calculate fracture toughness, after measuring crack length under 19,6N load applied for 20s. Results were evaluated by ANOVA and Tukey´s test. Results: Microhardness (VHN) of POM (637.9±53.6) was statistically greater (p<0.05) than ZIR (593.0±14.3), followed by EMP (519.1±21.5); no significant difference (p=0.206) was noted for elastic modulus (GPa) (ZIR: 71.5±9.0; POM: 67.3±4.4; EMP: 61.7±2.3). Fracture toughness (MPa/m) of POM (0.873±0.066) was statistically lower (p<0.05) than ZIR (0.977±0.021) and EMP (0.965±0.035). Conclusion: The results suggest that fluorapatite glass ceramic (ZIR) and leucite-reinforced glass ceramic (EMP) processed by heat pressing presented greater fracture toughness, improving clinical prognosis of metal free restorations.


Gomes EA, Assunção WG, Rocha EP, Santos PH. [Ceramic in dentistry: current state] Cerâmica. 2008;54:319-25. Portuguese.

Kelly JR, Benetti P. Ceramic materials in dentistry: historical evolution and current practice. Aust Dent J. 2011 Jun;56 Suppl 1:84-96. doi: 10.1111/j.1834-7819.2010.01299.x.

Bona AD, Mecholsky JJJ, Anusavice KJ. Fracture behavior of lithia-disilicate and leucite-based ceramics. Dent Mater. 2004 Dec;20(10):956-62.

Denry IL, Holloway JA. Elastic constants, Vickers hardness, and fracture toughness of fluorrichterite-based glass-ceramics. Dent Mater. 2004 Mar;20(3):213-9.

Gurram R, Krishna CHV, Reddy KM, Reddy GVKM, Shastry YM. Evaluating the fracture toughness and flexural strength of pressable dental ceramics: an in vitro study. J Indian Prosthodont Soc. 2014 Dec;14(4):358-62. doi: 10.1007/s13191-013-0331-1.

Cesar PF, Yoshimura HN, Miranda Jr WG, Miyazaki CL, Muta LM, Rodrigues Filho LE. Relationship between fracture toughness and flexural strength in dental porcelains. J Biomed Mater Res B Appl Biomater. 2006 Aug;78(2):265-73.

Alkadi L, Ruse D. Fracture toughness of two lithium disilicate dental glass ceramics. J Prosthet Dent. 2016 Oct;116(4):591-596. doi: 10.1016/j.prosdent.2016.02.009.

Ansong R, Flinn B, Chung KH, Mancl L, Ishibe M, Raigrodski AJ. Fracture toughness of heat-pressed and layered ceramics. J Prosthet Dent. 2013 Apr;109(4):234-40. doi: 10.1016/S0022-3913(13)60051-7.

Albakry M, Guazzato M, Swain MV. Influence of hot pressing on the microstructure and fracture toughness of two pressable dental glass–ceramics. J Biomed Mater Res B Appl Biomater. 2004 Oct 15;71(1):99-107.

Longhini D, Rocha COM, Medeiros IS, Fonseca RG, Adabo GL. Effect of glaze cooling rate on mechanical properties of conventional and pressed porcelain on zirconia. Braz Dent J. 2016 Sep-Oct;27(5):524-531. doi: 10.1590/0103-6440201600709.

Gorman CM, Horgan K, Dollard RP, Stanton KT. Effects of repeated processing on the strength and microstructure of a heat-pressed dental ceramic. J Prosthet Dent. 2014 Dec;112(6):1370-6. doi: 10.1016/j.prosdent.2014.06.015.

Tang X, Tang C, Su H, Luo H, Nakamura T, Yatani H. The effects of repeated heat-pressing on the mechanical properties and microstructure of IPS e.max Press. J Mech Behav Biomed Mater. 2014 Dec;40:390-396. doi: 10.1016/j.jmbbm.2014.09.016.

Amer R, Kurklu D, Johnston W. Effect of simulated mastication on the surface roughness of three ceramic systems. J Prosthet Dent. 2015 Aug;114(2):260-5. doi: 10.1016/j.prosdent.2015.02.018.

Taira M, Nomura Y, Wakasa K, Yamaki M, Matsui A. Studies on fracture toughness of dental ceramics. J Oral Rehabil. 1990 Nov;17(6):551-63.

Cesar PF, Bona AB, Scherrer SS, Tholey M, Noort RV, Vichi A, et al. ADM guidance - Ceramics: Fracture toughness testing and method selection. Dent Mater. 2017 Jun;33(6):575-584. doi: 10.1016/

Pagani C, Miranda CB, Bottino MC. [Relative fracture toughness of differents dental ceramics]. J Appl Oral Sci. 2003 Mar;11(1):69-75. Portuguese.

Rosemblum MA, Schulman A. A review of all-ceramic restorations. J Am Dent Assoc. 1997 Mar;128(3):297-307.

Scherrer SS, Kelly JR, Quinn GD, Xu K. Fracture toughness of a dental porcelain determined by fractographic analysis. Dent Mater. 1999 Sep;15(5):342-8.

Cesar PF, Yoshimura HN, Júnior WGM, Okada CY. Correlation between fracture toughness and leucite content in dental porcelains. J Dent. 2005 Oct;33(9):721-9.

Fahmy NZ, El Guindy J, Zamzam M. Effect of artificial saliva storage on microhardness and fracture toughness of a hydrothermal glass-ceramic. J Prosthodont. 2009 Jun;18(4):324-31. doi: 10.1111/j.1532-849X.2009.00448.x.

Suansuwan N, Swain MV. Determination of elastic properties of metal alloys and dental porcelains. J Oral Rehabil. 2001 Feb;28(2):133-9.

Anstis GR, Chantikul P, Lawn BR, Marshall DB. A critical evaluation of indentation techniques for measuring fracture toughness: I, Direct crack measurements. J Am Ceram Soc. 1981;64(9):533-8. doi: 10.1111/j.1151-2916.1981.tb10320.x.

Campbell SD. A comparative strength study of metal ceramic and all-ceramic esthetic materials: Modulus of rupture. J Prosthet Dent. 1989 Oct;62(4):476-9.

Domingues NB, Galvão BR, Ribeiro S, Almeida AAJ, Longhini D, Adabo GL. Comparison of the indentation strength and single-edge-v-notched-beam methods for dental ceramic fracture toughness testing. Dent Mater. 1998 Jul;14(4):246-55.

Elias CN, Lopes HP. [Dental materials: mechanical testing]. São Paulo: Santos; 2007. Portuguese.

Choi JR, Waddell JN, Swain MV. Pressed ceramics onto zirconia. Part 2: Indentation fracture and influence of cooling rate on residual stresses. Dent Mater. 2011 Nov;27(11):1111-8. doi: 10.1016/

Xiang Q, Liu Y, Sheng X, Dan X. Preparation of mica-based glass-ceramics with needle-like fluorapatite. Dent Mater. 2007 Feb;23(2):251-8.

Sebastiani M, Massimi F, Merlati G, Bemporad E. Residual micro-stress distributions in heat-pressed ceramic on zirconia and porcelain-fused to metal systems: Analysis by FIB-DIC ring core method and correlation with fracture toughness. Dent Mater. 2015 Nov;31(11):1396-405. doi: 10.1016/

The Brazilian Journal of Oral Sciences uses the Creative Commons license (CC), thus preserving the integrity of the articles in an open access environment.


Download data is not yet available.


Metrics Loading ...