Thermal Compatibility of Ceramic Veneers to a High Strength Core Material

Main Article Content

Pannapa Sinthuprasirt Sarah Pollington Richard van Noort

Abstract

The purpose of this study is to determine the extent to which the coefficient of thermal expansion mismatch between a veneering and core ceramic affects the thermal shock resistance. This study is also to establish what is the ideal coefficient of thermal expansion for a veneering ceramic in relation to its core ceramic. Veneering ceramics matching the CTE of three ceramic core materials were manufactured by measuring the CTE of ceramics with a range feldspar/high leucite ratios and using a linear regression equation. Discs of the core ceramics were veneered with varying wt% ratios of leucite/feldspar with CTE values ± 3 ppm/°C. The thermal shock resistance was determined by preheating the specimens to 90°C, quenching them in cold water, then reheating to 90°C followd by cooling to room temperature and inspecting for crazing. If no failure occurred, the specimens were tested at increasing increments of 10°C until failure. Statistical analysis was undertaken using two-way ANOVA and Tukey post-hoc tests for the CTE of the varying feldspar/high leucite compositions; and one-way ANOVA with Tukey’s multiple comparison tests for the thermal shock resistance. The CTE of the mixtures of feldspathic and leucite veneering ceramics presented as a linear equation, obeying the rule of mixtures, thus enabling matched CTE ceramic systems to be created. For IPS emax CAD and VITA In Ceram YZ, when veneered with their recommended ceramic, the mean ΔT values were significantly lower (192 ± 12°C and 179 ± 18°C) than when veneered with a ceramic with a matched CTE (225 ±15°C and 218 ± 9°C) (p<0.05). However, for the fluorcanasite, the matched CTE ceramic produced a mean ΔT value of 232 ± 25°C, which was significantly higher than the two commercial systems (p<0.05). Significance: For high strength ceramic cores, the best thermal shock resistance is achieved with a veneering ceramic that has a CTE the same as the core ceramic.

Keywords

Article Details

Section
Applied Science Research Articles

References

[1] M. Guazzato, M. Albakry , SP. Ringer, and MV. Swain MV, “Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part II. Zirconia-based dental ceramics,” Dent Mater, vol. 20, no. 5, pp. 449–456, 2004.

[2] MN. Aboushelib, M. Kler, JM. van Zel, and AJ. Feilzer, “Effect of veneering method on the fracture and bond strength of bilayered zirconia restorations,” International Journal of Prosthodontics, vol. 21, no. 3, pp. 237–240, 2008.

[3] G. Isgro, H. Wang, CJ. Kleverlaan, and AJ. Feilzer, “The effects of thermal mismatch and fabrication procedures on the deflection of layered all-ceramic disc,” Dent Mater, vol. 21, no. 7, pp. 649–655, 2005.

[4] G. Isgro, CJ. Kleverlaan, H. Wang, and AJ. Feilzer, “The influence of multiple firing on thermal contraction of ceramic materials used for the fabrication of layered all-ceramic dental restorations,” Dent Mater, vol. 21, no. 6, pp. 557–564, 2005.

[5] DW. Jones and PA. Jones, “Modulus of elasticity of dental ceramics,” Dent Pract Dent Rec, vol. 22, no. 5, pp. 170–173, 1972.

[6] WD. Kingery, HK. Bowen, and DR. Uhlmann, Introduction to Ceramics, 2nd ed. New York : Wiley, 1976, pp. 50–56.

[7] GP. Mora and WJ. O'Brien, “Thermal shock resistance of core reinforced all-ceramic crown systems,” Journal of Biomedical Materials Research Banner, vol. 28, no. 2, pp. 189–194, 1994.

[8] AA. Barrett, NJ. Grimaudo, KJ. Anusavice, and MC. Yang, “Influence of tab and disk design on shade matching of dental porcelain,” Journal of Prosthetic Dentistry, vol. 88, no. 6, pp. 591–597, 2002.

[9] KJ. Anusavice, RD. Ringle, PK. Morse, CW. Fairhurst, and GE. King, “A thermal shock test for porcelain-metal systems,” Journal of Dental Research, vol. 60, no. 9, pp. 1686–1691, 1981.

[10] KJ. Anusavice, “Dental ceramics,” in Philip's Science of Dental Materials, 11th ed. Missouri, Elsevier Saunders, 2003, pp. 441–447.

[11] K. Asaoka and JA. Tesk, “Transient and residual stress in a porcelain-metal strip,” Journal of Dental Research, vol. 69, no. 2, pp. 463–469, 1990.

[12] KJ. Anusavice, PH. DeHoff, SW. Twiggs, and PC. Lockwood, “Thermal shock resistance of porcelain discs,” Journal of Dental Research, vol. 62, no. 10, pp. 1082–1085, 1983.

[13] JP. Coffey, KJ. Anusavice, PH. DeHoff, RB. Lee, and B. Hojjatie, “Influence of contraction mismatch and cooling rate on flexural failure of PFM systems,” Journal of Dental Research, vol. 67, no. 1, pp. 61–65, 1988.

[14] JP. Nielsen and JJ.Tuccillo, “Calculation of interfacial stress in dental porcelain bonded to gold alloy substrate,” Journal of Dental Research, vol. 51, no. 4, pp. 1043–1047, 1972.

[15] G. Isgro, CJ. Kleverlaan, H. Wang, and AJ. Feilzer, “Thermal dimensional behavior of dental ceramics,” Biomaterials, vol. 25, no. 12, pp. 2447–2453, 2004.

[16] R. van Noort, “Dental ceramic,” in Introduction to Dental Materials, 2nd ed. Mosby Ltd., 2002, pp. 231–256.

[17] PJ. Steiner, JR. Kelly, and AA. Giuseppetti, “Compatibility of ceramic-ceramic systems for fixed prosthodontics,” International Journal of Prosthodontics, vol. 10, no. 4, pp. 375–380, 1997.