Monolithic CAD/CAM lithium disilicate versus veneered Y-TZP crowns: comparison of failure modes and reliability after fatigue.

PURPOSE The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate and hand-layer-veneered zirconia all-ceramic crowns. MATERIALS AND METHODS A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic lithium disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different step-stress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated. RESULTS Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic lithium disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM lithium disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the lithium disilicate ceramic in the range of 1,100 to 1,200 N. CONCLUSION Based on present fatigue findings, the application of CAD/CAM lithium disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures.

[1]  R. Giordano,et al.  Fracture surface analysis of dental ceramics: clinically failed restorations. , 1990, The International journal of prosthodontics.

[2]  M Heller,et al.  Mechanical properties and short-term in-vivo evaluation of yttrium-oxide-partially-stabilized zirconia. , 1989, Journal of biomedical materials research.

[3]  Irena Sailer,et al.  Five-year clinical results of zirconia frameworks for posterior fixed partial dentures. , 2007, The International journal of prosthodontics.

[4]  E. D. Rekow,et al.  Modeling of water absorption induced cracks in resin-based composite supported ceramic layer structures. , 2008, Journal of biomedical materials research. Part B, Applied biomaterials.

[5]  E. Elsayed,et al.  A general accelerated life model for step-stress testing , 2005 .

[6]  K. Wiedhahn From blue to white: new high-strength material for Cerec--IPS e.max CAD LT. , 2007, International journal of computerized dentistry.

[7]  J. J. Mecholsky,et al.  Fracture Surface Analysis of Dental Ceramics , 2011 .

[8]  K. Anusavice,et al.  Fracture Surface Characterization of Clinically Failed All-ceramic Crowns , 1994, Journal of dental research.

[9]  Andreas Bindl,et al.  Strength and fracture pattern of monolithic CAD/CAM-generated posterior crowns. , 2006, Dental materials : official publication of the Academy of Dental Materials.

[10]  L. Gauckler,et al.  Prospective clinical study of zirconia posterior fixed partial dentures: 3-year follow-up. , 2006, Quintessence international.

[11]  Andreas Bindl,et al.  Survival of ceramic computer-aided design/manufacturing crowns bonded to preparations with reduced macroretention geometry. , 2005, The International journal of prosthodontics.

[12]  K. Akca,et al.  CAD/CAM ZIRCONIA VS. SLIP-CAST GLASS-INFILTRATED ALUMINA/ZIRCONIA ALL-CERAMIC CROWNS: 2-YEAR RESULTS OF A RANDOMIZED CONTROLLED CLINICAL TRIAL , 2009, Journal of applied oral science : revista FOB.

[13]  Moen Bd,et al.  Nineteen fifty survey of the dental profession. VI. Dental services rendered. , 1951 .

[14]  M. Molin,et al.  Five-year clinical prospective evaluation of zirconia-based Denzir 3-unit FPDs. , 2008, The International journal of prosthodontics.

[15]  N. Heussen,et al.  Clinical behavior of zirconia-based fixed partial dentures made of DC-Zirkon: 3-year results. , 2008, The International journal of prosthodontics.

[16]  M V Swain,et al.  Unstable cracking (chipping) of veneering porcelain on all-ceramic dental crowns and fixed partial dentures. , 2009, Acta biomaterialia.

[17]  Ariel J Raigrodski,et al.  The efficacy of posterior three-unit zirconium-oxide-based ceramic fixed partial dental prostheses: a prospective clinical pilot study. , 2006, The Journal of prosthetic dentistry.

[18]  P. Petsche,et al.  Influence of glass-ceramic thickness on Hertzian and bulk fracture mechanisms. , 1998, The International journal of prosthodontics.

[19]  K J Anusavice,et al.  Structural reliability of alumina-, feldspar-, leucite-, mica- and zirconia-based ceramics. , 2000, Journal of dentistry.

[20]  P Schärer,et al.  [Clinical study of zirconium oxide bridges in the posterior segments fabricated with the DCM system]. , 2000, Schweizer Monatsschrift fur Zahnmedizin = Revue mensuelle suisse d'odonto-stomatologie = Rivista mensile svizzera di odontologia e stomatologia.

[21]  Krister Nilner,et al.  All-ceramic two- to five-unit implant-supported reconstructions. A randomized, prospective clinical trial. , 2006, Swedish dental journal.

[22]  R. Mericske-Stern,et al.  Zirconia for teeth and implants: a case series. , 2008, The International journal of periodontics & restorative dentistry.

[23]  T. Donovan Factors essential for successful all-ceramic restorations. , 2008, Journal of the American Dental Association.

[24]  Charles J Goodacre,et al.  Clinical complications in fixed prosthodontics. , 2003, The Journal of prosthetic dentistry.

[25]  B. Lawn,et al.  Use of contact testing in the characterization and design of all-ceramic crownlike layer structures: a review. , 2001, The Journal of prosthetic dentistry.

[26]  Irena Sailer,et al.  A systematic review of the survival and complication rates of all‐ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part II: fixed dental prostheses. , 2007 .

[27]  E. D. Rekow,et al.  Laboratory Simulation of Y-TZP All-ceramic Crown Clinical Failures , 2009, Journal of dental research.

[28]  M. Zwahlen,et al.  A systematic review of the survival and complication rates of all-ceramic and metal-ceramic reconstructions after an observation period of at least 3 years. Part I: Single crowns. , 2007, Clinical oral implants research.

[29]  R. Draughn Compressive Fatigue Limits of Composite Restorative Materials , 1979, Journal of dental research.

[30]  Atilla Sertgöz,et al.  Two-year clinical evaluation of lithia-disilicate-based all-ceramic crowns and fixed partial dentures. , 2006, Dental materials : official publication of the Academy of Dental Materials.

[31]  Massimiliano Guazzato,et al.  Strength, reliability and mode of fracture of bilayered porcelain/zirconia (Y-TZP) dental ceramics. , 2004, Biomaterials.

[32]  B. Lawn Indentation of Ceramics with Spheres: A Century after Hertz , 1998 .

[33]  B. Lawn,et al.  Lifetime-limiting Strength Degradation from Contact Fatigue in Dental Ceramics , 2000, Journal of dental research.

[34]  V. Thompson,et al.  Sliding Contact Fatigue Damage in Layered Ceramic Structures , 2007, Journal of dental research.

[35]  Anders Ortorp,et al.  A 3-year retrospective and clinical follow-up study of zirconia single crowns performed in a private practice. , 2009, Journal of dentistry.

[36]  J. E. Ritter Predicting lifetimes of materials and material structures. , 1995, Dental materials : official publication of the Academy of Dental Materials.

[37]  Jonathan C Knowles,et al.  Fatigue and fracture properties of yttria partially stabilized zirconia crown systems. , 2008, Dental materials : official publication of the Academy of Dental Materials.

[38]  C. Marchack,et al.  Customization of milled zirconia copings for all-ceramic crowns: a clinical report. , 2008, The Journal of prosthetic dentistry.

[39]  Yu Zhang,et al.  Effect of veneering techniques on damage and reliability of Y-TZP trilayers. , 2009, The European journal of esthetic dentistry : official journal of the European Academy of Esthetic Dentistry.

[40]  T. Eliades,et al.  Dental Materials In Vivo: Aging and Related Phenomena. , 2003 .

[41]  P Carlson,et al.  All-ceramic fixed partial dentures designed according to the DC-Zirkon technique. A 2-year clinical study. , 2005, Journal of oral rehabilitation.

[42]  E. D. Rekow,et al.  Effect of water storage time and composite cement thickness on fatigue of a glass-ceramic trilayer system. , 2008, Journal of biomedical materials research. Part B, Applied biomaterials.

[43]  J. Strub,et al.  Survival rates of IPS empress 2 all-ceramic crowns and fixed partial dentures: results of a 5-year prospective clinical study. , 2006, Quintessence international.

[44]  R. Stevens,et al.  Applications of Zirconia Ceramics , 1996 .

[45]  E. D. Rekow,et al.  Fatigue testing of two porcelain-zirconia all-ceramic crown systems. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[46]  B. Lawn,et al.  Role of microstructure on contact damage and strength degradation of micaceous glass-ceramics. , 1998, Dental materials : official publication of the Academy of Dental Materials.

[47]  W. Mörmann,et al.  Strength of CAD/CAM-generated esthetic ceramic molar implant crowns. , 2008, The International journal of oral & maxillofacial implants.