Document Type : Original Article

Authors

1 Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.

2 Postgraduate Student, Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.

Abstract

Statement of the Problem: Increasing the sintering temperature is suggested by some manufacturers as a way to enhance the translucency of monolithic zirconia crowns. Meanwhile, its effect on the marginal fit and compressive strength of the restoration is not fully understood.
Purpose: This study aimed to evaluate the effect of sintering temperature on the marginal fit and compressive strength of monolithic zirconia crowns.
Materials and Method: In this in vitro study, thirty crowns of pre-sintered monolithic zirconia were milled and sintered in a special furnace at either 1450°C or 1550°C (n=15 per group). The marginal gaps were measured at 18 spots on the dies with a digital microscope. To evaluate the compressive strength, the specimens were cemented on brass dies by using conventional glass ionomer cement. Vertical load was applied by a universal testing machine until fracture. One-way ANOVA test was used to analyze the results (α=0.05).
Results: The marginal gap was not significantly different between the two groups (p= 0.062). A significantly higher mean value of compressive strength was observed in crowns sintered at 1550°c (1988.27±635.09 N) than those sintered at 1450 °c (1514.27±455.11 N) (p= 0.026).
Conclusion: Although increasing the sintering temperature would not affect the marginal gap of monolithic zirconia crowns, it could significantly improve the compressive strength of zirconia restorations.

Keywords

  • Vagkopoulou T, Koutayas SO, Koidis P, Strub JR. Zirconia in dentistry: Part 1. Discovering the nature of an upcoming bioceramic. Eur J Esthet Dent. 2009;4:130-51.
  • Zhang H, Kim BN, Morita K, Hiraga HYK, Sakka Y. Effect of sintering temperature on optical properties and microstructure of translucent zirconia prepared by high-pressure spark plasma sintering. Sci Technol Adv Mater. 2011; 12: 055003.
  • Tinschert J, Zwez D, Marx R, Anusavice K. Structural reliability of alumina-, feldspar-, leucite-, mica-and zirconia-based ceramics. J Dent. 2000; 28: 529-535.
  • Chevalier J. What future for zirconia as a biomaterial? Biomaterials. 2006;27:535-543.
  • Denry I, Kelly JR. State of the art of zirconia for dental applications. Dental materials: official publication of the Dent Mat. 2008; 24: 299-307.
  • Raigrodski AJ, Hillstead MB, Meng GK, Chung KH. Survival and complications of zirconia-based fixed dental prostheses: A systematic review. J Prosthet Dent. 2012; 107: 170-177.
  • Lameira DP, De Souza GM. Fracture strength of aged monolithic and bilayer zirconia-based crowns. BioMed Res Int. 2015; 2015: 418641.
  • Zhao K, Wei YR, Pan Y, Zhang XP, Swain MV, Guess PC. Influence of veneer and cyclic loading on failure behavior of lithium disilicate glass-ceramic molar crowns. Dent Mater. 2014;30:164-171.
  • Nordahl N, von Steyern PV, Larsson C. Fracture strength of ceramic monolithic crown systems of different thickness. J Oral Sci. 2015;57:255-61.
  • Heffernan MJ, Aquilino SA, Diaz-Arnold AM, Haselton DR, Stanford CM, Vargas MA. Relative translucency of six all-ceramic systems. Part i: Core materials. J Prosthet Dent. 2002; 88: 4-9.
  • Jiang L, Liao Y, Wan Q, Li W. Effects of sintering temperature and particle size on the translucency of zirconium dioxide dental ceramic. J Mater Sci Med. 2011; 22: 2429-2435.
  • Stawarczyk B, Özcan M, Hallmann L, Ender A, Mehl A, Hämmerlet CHF. The effect of zirconia sintering temperature on flexural strength, grain size, and contrast ratio. Clin Oral Investig. 2013; 17: 269-274.
  • Becher PF, Swain MV. Grain-size-dependent transformation behavior in polycrystalline tetragonal zirconia. J Am Ceram Soc. 1992; 75: 493-502.
  • Lange F. Transformation toughening. Part 1. Size effects associated with the thermodynamics of constrained transformations. J Mater Sci. 1982; 17: 225-234.
  • Lange F. Transformation toughening. Part 3. Experimental observations in the zro sub (2)-y sub (2) o sub (3) system. J Mater Sci. 1982; 17: 240-246.
  • Ruiz L, Readey MJ. Effect of heat treatment on grain size, phase assemblage, and mechanical properties of 3 mol% ytzp. J Am Ceram Soc. 1996; 79: 2331-240.
  • Derafshi R, Khorshidi H, Kalantari M, Ghaffarlou I. Effect of mouthrinses on color stability of monolithic zirconia and feldspathic ceramic: An in vitro BMC Oral Health. 2017; 17: 129.
  • Ersoy NM, Aydoğdu HM, Değirmenci BÜ, Çökük N, Sevimay M. The effects of sintering temperature and duration on the flexural strength and grain size of zirconia. Acta Biomater Odontol Scand. 2015; 1: 43-50.
  • Hjerppe J, Vallittu PK, Fröberg K, Lassila LVJ. Effect of sintering time on biaxial strength of zirconium dioxide. Dent Mater. 2009; 25: 166-171.
  • Hu L, Wang C-A. Effect of sintering temperature on compressive strength of porous yttria-stabilized zirconia ceramics. Ceram Int. 2010; 36: 1697-1701.
  • Kim MJ, Ahn JS, Kim JH, Kim HY, Kim WC. Effects of the sintering conditions of dental zirconia ceramics on the grain size and translucency. J Adv Prosthodont. 2013; 5: 161-166.
  • Khaledi AAR, Vojdani M, Farzin M, Pirouzi S. The effect of sintering program on the compressive strength of zirconia copings. J Dent (Shiraz). 2018; 19: 206-211.
  • Christensen GJ. Marginal fit of gold inlay castings. J Prosthet Dent. 1966; 16: 297-305.
  • McLean JW, von Fraunhofer JA. The estimation of cement film thickness by an in vivo Br Dent J. 1971; 131: 107-111.
  • Euán R, Figueras-Álvarez O, Cabratosa-Termes J, Oliver-Parra R. Marginal adaptation of zirconium dioxide copings: Influence of the cad/cam system and the finish line design. J Prosthet Dent. 2014; 112: 155-162.
  • Bhowmik H, Parkhedkar R. A comparison of marginal fit of glass infiltrated alumina copings fabricated using two different techniques and the effect of firing cycles over them. J Adv Prosthodont. 2011;3:196-203.
  • Ural Ç, Burgaz Y, Saraç D. In vitro evaluation of marginal adaptation in five ceramic restoration fabricating techniques. Quintessence Int. 2010;41:585-590.
  • Pak HS, Han JS, Lee JB, Kim SH, Yang JH. Influence of porcelain veneering on the marginal fit of digident and lava cad/cam zirconia ceramic crowns. J Adv Prosthodont. 2010; 2: 33-38.
  • Kohorst P, Brinkmann H, Dittmer MP, Borchers L, Stiesch M. Influence of the veneering process on the marginal fit of zirconia fixed dental prostheses. J Oral Rehabil. 2010; 37: 283-291.
  • Balkaya MC, Cinar A, Pamuk S. Influence of firing cycles on the margin distortion of 3 all-ceramic crown systems. J Prosthet Dent. 2005; 93: 346-355.
  • Rastogi A, Kamble V. Comparative analysis of the clinical techniques used in evaluation of marginal accuracy of cast restoration using stereomicroscopy as gold standard. J Adv Prosthodont. 2011; 3: 69-75.
  • Tekeli S, Erdogan M. A quantitative assessment of cavities in 3 mol% yttria-stabilized tetragonal zirconia specimens containing various grain size. Ceram Int. 2002; 28: 785-789.
  • Chevalier J, Deville S, Münch E, Jullian R, Lair F. Critical effect of cubic phase on aging in 3mol% yttria-stabilized zirconia ceramics for hip replacement prosthesis. Biomaterials. 2004; 25: 5539-5545.
  • Scott HG. Phase relationships in the zirconia-yttria system. J Mater Sci. 1975; 10: 1527-1535.
  • Chevalier J, Olagnon C, Fantozzi G. Subcritical crack propagation in 3y-tzp ceramics: Static and cyclic fatigue. J Am Ceram Soc. 1999; 82: 3129-3138.
  • Leevailoj C, Platt JA, Cochran MA, Moore BK. In vitro study of fracture incidence and compressive fracture load of all-ceramic crowns cemented with resin-modified glass ionomer and other luting agents. J Prosthet Dent. 1998; 80: 699-707.
  • Bernal G, Jones RM, Brown DT, Munoz CA, Goodacre CJ. The effect of finish line form and luting agent on the breaking strength of dicor crowns. Int J Prosthodont. 1993; 6: 286-290.
  • Al-Makramani BMA, Razak AAA, Abu-Hassan MI. Evaluation of load at fracture of procera allceram copings using different luting cements. J Prosthodont. 2008; 17: 120-124.
  • Akesson J, Sundh A, Sjogren G. Fracture resistance of all-ceramic crowns placed on a preparation with a slice-formed finishing line. J Oral Rehabil. 2009; 36: 516-623.
  • Wood KC, Berzins DW, Luo Q, Thompson GA, Toth JM, Nagy WW. Resistance to fracture of two all-ceramic crown materials following endodontic access. J Prosthet Dent. 2006; 95: 33-34.