Fracture Resistance of Zirconia Restorations with a Modified Framework Design
Objectives: Chipping is one of the concerns related to zirconia crowns. The reasons of chipping have not been completely understood. This in-vitro study aimed to assess the effect of coping design on the fracture resistance of all-ceramic single crowns with zirconia frameworks.
Materials and Methods: Two types of zirconia copings were designed (n=12): (1) a standard coping (SC) with a 0.5mm uniform thickness and (2) a modified coping (MC) consisted of a lingual margin of 1mm thickness and 2mm height connected to a proximal strut of 4mm height and a 0.3mm-wide facial collar. After veneer porcelain firing, the crowns were cemented to metal dies. Afterwards, a static vertical load was applied until failure. The modes of failure were determined. Data were calculated and statistically analyzed by independent samples T-test. P<0.05 was considered statistically significant.
Results: The mean and standard deviation (SD) of the final fracture resistance equaled to 3519.42±1154.96 N and 3570.01±1224.33 N in SC and MC groups, respectively; the difference was not statistically significant (P=0.9). Also, the mean and SD of the initial fracture resistance equaled to 3345.34±1190.93 N and 3471.52±1228.93 N in SC and MC groups, respectively (P=0.8). Most of the specimens in both groups showed the mixed failure mode.
Conclusions: Based on the results, the modified core design may not significantly improve the fracture resistance.
- Larsson C, El Madhoun S, Wennerberg A, Vult von Steyern P. Fracture strength of yttria-stabilized tetragonal zirconia polycrystals crowns with different design: an in vitro study. Clin Oral Implants Res. 2012 Jul;23(7):820-6.
- Della Bona A, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc. 2008 Sep;139 Suppl:8S-13S.
- Kokubo Y, Tsumita M, Kano T, Fukushima S. The influence of zirconia coping designs on the fracture load of all-ceramic molar crowns. Dent Mater J. 2011 May;30(3):281-5.
- Rekow ED, Silva NR, Coelho PG, Zhang Y, Guess P, Thompson VP. Performance of dental ceramics: challenges for improvements. J Dent Res. 2011 Aug; 90(8):937-952.
- Reich S, Petschelt A, Lohbauer U. The effect of finish line preparation and layer thickness on the failure load and fractography of ZrO2 copings. J Prosthet Dent. 2008 May;99(5):369-376.
- Pogoncheff CM, Duff RE. Use of zirconia collar to prevent interproximal porcelain fracture: A clinical report. J Prosthet Dent. 2010 Aug;104(2):77-79.
- Monaco C, Tucci A, Esposito L, Scotti R. Microstructural changes produced by abrading Y-TZP in presintered and sintered conditions. J Dent. 2013 Feb;41(2):121-6.
- Kou W, Sjogren G. Fracture behaviour of zirconia FPDs substructures. J Oral Rehabil. 2010 Apr;37(4):292-9.
- Benetti P, Della Bona A, Kelly JR. Evaluation of thermal compatibility between core and veneer dental ceramics using shear bond strength test and contact angle measurement. Dent Mater. 2010 Aug;26(8):743-50.
- Tholey MJ, Swain MV, Thiel N. Thermal gradients and residual stresses in veneered Y-TZP frameworks. Dent Mater. 2011 Nov;27(11):1102-10.
- Nakamura K, Adolfsson E, Milleding P, Kanno T, Ortengren U. Influence of grain size and veneer firing process on the flexural strength of zirconia ceramics. Eur J Oral Sci. 2012 Jun;120(3):249-54.
- Fischer J, Grohmann P, Stawarczyk B. Effect of zirconia surface treatments on the shear strength of zirconia/veneering ceramic composites. Dent Mater J. 2008 May;27(3):448-54.
- Cattani Lorente M, Scherrer SS, Richard J, Demellayer R, Amez-Droz M, Wiskott HW. Surface roughness and EDS characterization of a Y-TZP dental ceramic treated with the CoJetTM Sand. Dent Mater. 2010 Nov;26(11):1035-42.
- Salimi H, Mosharraf R, Savabi O. Effect of framework design on fracture resistance of zirconium oxide posterior fixed partial dentures. Dent Res J (Isfahan). 2012 Nov;9(6):764-9.
- Son YH, Han CH, Kim S. Influence of internal-gap width and cement type on the retentive force of zirconia copings in pullout testing. J Dent. 2012 Oct;40(10):866-72.
- Inokoshi M, Kameyama A, De Munck J, Minakuchi S, Van Meerbeek B. Durable bonding to mechanically and/or chemically pre-treated dental zirconia. J Dent. 2013 Feb;41(2):170-9.
- Tang X, Tan Z, Nakamura T, Yatani H. Effects of aging on surface textures of veneering ceramics for zirconia frameworks. J Dent. 2012 Nov;40(11):913-20.
- Miller LL. Framework design in ceramo-metal restorations. Dent Clin North Am. 1977 Oct;21(4):699-716.
- Bonfante EA, da Silva NR, Coelho PG, Bayardo-Gonzalez DE, Thompson VP, Bonfante G. Effect of framework design on crown failure. Eur J Oral Sci. 2009 Apr;117(2):194-9.
- Beuer F, Aggstaller H, Edelhoff D, Gernet W. Effect of preparation design on the fracture resistance of zirconia crown copings. Dent Mater J. 2008 May;27(3):362-7.
- Rosentritt M, Steiger D, Behr M, Handel G, Kolbeck C. Influence of substructure design and spacer settings on the in vitro performance of molar zirconia crowns. J Dent. 2009 Dec;37(12):978-83.
- Sundh A, Sjogren G. A comparison of fracture strength of yttrium-oxide- partially-stabilized zirconia ceramic crowns with varying core thickness, shapes and veneer ceramics. J Oral Rehabil. 2004 Jul;31(7):682-8.
- Dejak B, Mlotkowski A, Romanowicz M. Finite element analysis of stresses in molars during clenching and mastication. J Prosthet Dent. 2003 Dec;90(6):591-7.
- Rafferty BT, Janal MN, Zavanelli RA, Silva NR, Rekow ED, Thompson VP, et al. Design features of a three-dimensional molar crown and related maximum principal stress. A finite element model study. Dent Mater. 2010 Feb;26(2):156-63.
- Ha SR, Kim SH, Han JS, Yoo SH, Jeong SC, Lee JB, et al. The influence of various core designs on stress distribution in the veneered zirconia crown: a finite element analysis study. J Adv Prosthodont. 2013 May;5(2):187-97.
- Marchack BW, Futatsuki Y, Marchack CB, White SN. Customization of milled zirconia copings for all-ceramic crowns: a clinical report. J Prosthet Dent. 2008 Mar;99(3):169-73.
- Lorenzoni FC, Martins LM, Silva NR, Coelho PG, Guess PC, Bonfante EA, et al. Fatigue life and failure modes of crowns systems with a modified framework design. J Dent. 2010 Aug;38(8):626-34.
- Silva NR, Bonfante EA, Rafferty BT, Zavanelli RA, Rekow ED, Thompson VP, et al. Modified Y-TZP core design improves all-ceramic crown reliability. J Dent Res. 2011 Jan;90(1):104-8.
- Bonfante EA, Rafferty B, Zavanelli RA, Silva NR, Rekow ED, Thompson VP, et al. Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core-veneer all-ceramic layered crown design. Eur J Oral Sci. 2010 Apr;118(2):202-9.
- Scherrer SS, de Rijk WG. The fracture resistance of all-ceramic crowns on supporting structures with different elastic moduli. Int J Prosthodont. 1993 Sep-Oct;6(5):462-7.
- Mori K. Influence of the design of zirconia framework on the fracture strength of veneering porcelain. Kokubyo Gakkai Zasshi. 2010 Mar;77(1):67-70.
- Kelly JR. Perspectives on strength. Dent Mater. 1995 Mar;11(2):103-10.
- Burke FJ. The effect of variations in bonding procedure on fracture resistance of dentin-bonded all-ceramic crowns. Quintessence Int. 1995 Apr;26(4):293-300.