Crack Initiation Modes in Bilayered Alumina/Porcelain Disks as a Function of Core/Veneer Thickness Ratio and Supporting Substrate Stiffness

Abstract

We hypothesize that the fracture resistance of alumina core/porcelain veneer disks increases and that crack initiation shifts from veneer to core as the core/veneer thickness ratio (t_c/t_v) increases from 0.5/1.0 to 1.3/0.2, or as the elastic modulus of the supporting substrate (E_s) to which it is resin-bonded increases from 5.1 to 226 GPa. When supported by a low-modulus substrate, disks with low tc/tv ratios exhibited cracks in the veneer and within the core, while those with high t_c/t_v ratios demonstrated core cracks, but not veneer cracks. None of the disks supported by Ni-Cr alloy (E = 226 GPa) exhibited core cracks. These results support the hypothesis that the crack initiation site shifts as the t_c/t_v ratio increases, but the increase in Es did not affect the crack initiation site. This study suggests that the t_c/t_v ratio is the dominant factor that controls the failure initiation site in bilayered ceramic disks.

Keywords

alumina core elastic modulus failure mode failure load finite element stress analysis.

Get full access to this article

View all access options for this article.

References

Abacus Concepts (1992). Statview 4.1 user's guide. Berkeley, CA: Abacus Concepts, Inc.

Anusavice KJ , Tsai YL ( 1997). Stress distribution in ceramic crown forms as a function of thickness, elastic modulus, and supporting substrate. Proceedings of the Sixteenth Southern Biomedical Engineering Conference, Bumgardner JD , Puckett AD , editors. Biloxi, MS: IEEE, pp. 264-267.

Campbell SD (1989). A comparative strength study of metal ceramic and all ceramic esthetic materials: modulus of rupture. J Prosthet Dent 62:476-479.

Kelly JR , Tesk JA , Sorensen JA (1995). Failure of all-ceramic fixed partial dentures in vitro and in vivo: analysis and modeling. J Dent Res 74:1253-1258.

Scherrer SS , de Rijk WG (1993). The fracture resistance of all-ceramic crowns on supporting structures with different elastic moduli. Int J Prosthodont 6:462-467.

Tsai YL , Petsche PE , Anusavice KJ , Yang MC ( 1998). Influence of glass-ceramic thickness on Hertzian and bulk fracture mechanisms. Int J Prosthodont 11 :27-32.

White SN , Caputo AA , Vidjak Fma , Seghi RR (1994). Moduli of rupture of layered dental ceramics. Dent Mater 10:52-58.

Wuttiphan S. , Lawn BR , Padture NP (1996). Crack suppression in strongly bonded homogeneous/heterogeneous laminates: a study on glass/glass-ceramic bilayers. J Am Ceram Soc 79:634-640.

Zeng K. , Oden A. , Rowcliffe D. (1998). Evaluation of mechanical properties of dental ceramic core materials in combination with porcelains. Int J Prosthodont 11:183-189.