The era of monolithic translucent zirconia
Despoina Chatzistavrianou, Shakeel Shahdad, and Philip Taylor evaluate the long-term outcomes of monolithic translucent zirconia – an increasingly popular restorative material
Monolithic translucent zirconia restorations offer improved aesthetics, minimal tooth reduction and elimination of ceramic chipping compared to traditional zirconia cores with veneered ceramic, but the scientific evidence on the survival of this type of restoration is scarce.
This article presents two case reports demonstrating rehabilitation with monolithic translucent zirconia restorations and discusses the clinical challenges of this treatment modality.
A patient with history of trauma to her maxillary anterior teeth and a patient with amelogenesis imperfecta were rehabilitated with monolithic translucent zirconia restorations. After 16 and nine months respectively, the patients were satisfied with function and aesthetics and no complications were noticed in the restorations or the opposing teeth.
Yttria-stabilised zirconia polycrystalline (Y-TZP) ceramics were introduced as a biomaterial in restorative dentistry to eliminate the incidence of bulk fracture in all-ceramic restorations (Conrad et al, 2007). They attracted the interests of clinicians due to their high flexural strength and fracture toughness (Guazzato et al, 2004a; Guazzato et al, 2004b).
Their five-year survival rate ranges from 93.5% to 97.8% for tooth-supported prostheses and from 97.1% to 100% for implant-supported prostheses (Le, 2015; Larsson and Wennerberg, 2014; Sailer et al, 2007).
Chipping of the veneering ceramic with incidence of 15.7% has been reported as the most common complication both for tooth- and implant-supported prostheses (Sailer et al, 2007; Sailer et al, 2015; Pjetursson et al, 2015). Also, this type of prosthesis requires heavy tooth reduction and the reduced translucency of the core compromises the aesthetic outcome; factors that limit their use (Goodacre et al, 2001; Heffernan et al, 2002).
Recently, monolithic translucent zirconia restorations were introduced in an effort to eliminate chipping of the veneering material, allowing minimal occlusal and axial tooth reduction of 0.5mm – compared to conventional zirconia restorations, which require reduction of 1.5-2mm (Nakamura et al, 2015).
The fracture resistance of monolithic translucent zirconia restorations is considerably higher than that of veneered zirconia cores and glass ceramics (Johansson et al, 2014), but a minimal thickness of 0.5mm is essential for optimal mechanical properties (Nakamura et al, 2015).
Monolithic translucent zirconia restorations show less wear to the antagonist tooth compared to traditional zirconia cores and glass ceramics (Mundhe et al, 2015; Rosentritt et al, 2012; Cardelli et al, 2015), irrespective of whether they are polished or glazed (Jung et al, 2010). Careful polishing is recommended after adjusting the prosthesis to keep surface roughness and phase transformation low (Preis, 2015).
Furthermore, the increased translucency of monolithic translucent zirconia restorations results in improved aesthetic outcomes compared to traditional zirconia cores (Harianawala, 2014).
The introduction of a variety of shades, application of colouring liquids to the core and staining of the occlusal surface improves the aesthetic properties of monolithic zirconia restorations (Rinke and Fischer, 2013). Besides, they are claimed to be cost-effective restorations as ceramic veneering is not required.
Preliminary outcomes show high survival rates both for full-arch and single-unit tooth- and implant-supported prosthesis (Carames et al, 2015; Venezia et al, 2015; Moscovitch, 2015).
Carames et al (2015) followed 14 patients with full-arch implant-supported prostheses for 24 months and showed a 96% survival rate. Other studies (Venezia et al, 2015; Moscovitch, 2015) have shown 100% survival over a 36- and 68-month follow-up period.
The aim of this article is to present two case reports of patients who were rehabilitated with monolithic translucent zirconia restorations and discuss the clinical challenges of this treatment modality.
Clinical report one
A 25-year-old female patient with a history of trauma to her maxillary anterior teeth presented requiring restoration of the traumatised teeth.
The fractured maxillary central incisors were provisionally restored with composite restorations and the maxillary lateral incisors had fractured at the cervical margin.
Intraoral and radiographic examination confirmed the diagnoses of failing restorations in the maxillary central incisors, intruded maxillary right central incisor and chronic apical periodontitis in the two maxillary incisors. The maxillary lateral incisors were retained as roots (Figures 1 and 2).
The treatment plan included full-coverage crowns to restore the maxillary central incisors and single-tooth implant-supported crowns to replace the maxillary lateral incisors. A high lip line and the patient’s high aesthetic expectations indicated the use of all-ceramic restorations to restore the traumatised teeth.
The preoperative treatment planning was based on the SAC assessment tool (Dawson et al, 2009) and involved diagnostic wax-ups, cone-beam computed tomography (CBCT) and use of radiographic and surgical stents (Mericske-Stern et al, 2000). Root canal treatment was performed in the maxillary central incisors prior to implant placement to eliminate any active infection (Martin et al, 2009).
Type II (early-delayed) implant placement surgery with simultaneous guided bone regeneration was performed in the maxillary lateral incisor sites to augment ridge contour with deproteinised bovine bone and porcine collagen membrane (Geistlich Biooss and Biogide) (Buser et al, 2009; Hämmerle et al, 2004; Chen et al, 2009).
Crown lengthening surgery was performed in the upper left central incisor at the time of implant placement to correct the irregular gingival contour.
After an uneventful healing period of three months, provisional restorations were placed in the maxillary lateral incisors to create an optimal emergence profile.
Provisional crowns were also placed on the two central incisors based on the diagnostic wax-up aiming to assess function and aesthetics (Jemt, 1999; Moscovitch and Saba, 1996; Lewis et al, 1995).
Lithium disilicate cement-retained crowns (IPS E.max, Ivoclar Vivadent) on zirconia abutments (Straumann Cares abutment, zirconium dioxide) were planned as definitive restorations for the lateral incisors and the monolithic translucent zirconia crowns (Straumann Cares monolithic restorations) for the central incisors (Stawarczyk et al, 2011).
As a result of trauma, the remaining tooth structure in the central incisors was limited and mainly presented palatally. The use of monolithic translucent zirconia crowns allowed minimal tooth reduction of 0.5mm palatally and 1mm labially.
The zirconia abutments and cores were scanned with a CS2 scanner and the Cares visual software (Straumann Cares System 8.0) (Kapos and Evan, 2014). The monolithic translucent zirconia crowns for the central incisors were stained to optimise the aesthetic outcome (Rinke and Fischer, 2013).
The zirconia abutments were screwed and tightened to 35Ncm on each implant and the screw access holes were sealed with composite restorative material. Subsequently, the implant crowns were cemented using soft temporary cement (Tempbond, Kerr) (Mehl et al, 2008). The monolithic translucent zirconia crowns on the central incisors were cemented with a resinous cement with zirconia primer (Multilink Automix, Ivoclar Vivadent) (Thompson et al, 2011).
The patient was satisfied with the functional and aesthetic outcome at the end of the treatment and no complications were noticed at the 16-month review appointment.
Clinical report two
A 25-year-old female patient with amelogenesis imperfecta required restorations of her posterior teeth to improve function and eliminate tooth sensitivity. The maxillary and mandibular anterior teeth were previously restored with definitive restorations.
Intraoral and radiographic examination confirmed the diagnoses of hypocalcified type of amelogenesis imperfecta and acquired tooth loss of the mandibular right first molar (Figures 5 and 6) (Gadhia et al, 2012).
The treatment plan involved adhesive onlays to restore the maxillary and mandibular posterior teeth. Inadequate interocclusal space was present between the molar teeth and the patient was not willing to accept metal restorations for the definitive prostheses. Preparation for glass ceramic onlays could have detrimental effects on the tooth vitality.
Monolithic translucent zirconia onlays on the molar teeth were planned to facilitate the rehabilitation allowing minimal tooth reduction of 0.5mm.
The preoperative treatment planning involved articulated study models and diagnostic wax ups (Malik et al, 2012). After completion of the diagnostic stages of the treatment plan, the definitive restorations were constructed using monolithic translucent zirconia onlays (Straumann Cares monolithic restorations) for the molar teeth and lithium disilicate onlays (IPS E.max, Ivoclar Vivadent) for the premolar teeth (Malik et al, 2012).
The casts were scanned with CS2 scanner and the Cares Visual software (Straumann Cares System 8.0) (Kapos and Evans, 2014).
Subsequently, the restorations were stained to achieve an optimal colour match (Rinke and Fischer, 2013). All restorations were cemented with a resinous cement with zirconia primer (Multilink Automix, Ivoclar Vivadent) (Figures 7 and 8) (Thompson et al, 2011).
The patient was satisfied with the functional and aesthetic outcome at the end of the treatment, tooth sensitivity was controlled and no complications were noticed in the teeth or restorations at the nine-month review appointment.
The literature review revealed that the long-term survival of monolithic translucent zirconia restorations lacks evidence. Nevertheless, improved properties regarding aesthetics, tooth reduction and ceramic chipping in comparison to traditional zirconia cores are reported (Nakamura et al, 2015; Jung et al, 2010; Harianawala et al, 2014).
Preliminary outcomes show high survival rates for full-arch and single-unit tooth- and implant-supported prosthesis (Carames et al, 2015; Venezia et al, 2015; Moscovitch, 2015), but longer observation periods are necessary to draw definitive conclusions.
Traditionally, metal restorations have been used in patients with developmental conditions, especially in cases of reduced interocclusal space, which show good long-term outcomes but compromised aesthetics (Gadhia et al, 2012; Malik et al, 2012).
Monolithic translucent zirconia restorations could offer an alternative restorative material in cases of reduced interocclusal space where aesthetic requirements are critical allowing minimal tooth reduction of 0.5mm (Nakamura et al, 2015).
Careful polishing after adjusting the zirconia surfaces to prevent wear to the opposing teeth and cementation with a resinous cement with zirconia primer are prerequisite to a successful outcome (Preis et al, 2015; Rinke and Fischer, 2013).
There are limitations on the use of monolithic zirconia restorations. Their fabrication requires computer-aided design and computer-aided manufacturing (CAD/CAM) technology and a multi-step polishing protocol after occlusal adjustment, which requires a variety of special diamond burs, diamond-impregnated silicone instruments and diamond pastes. Besides, there is no evidence regarding the effect on the survival of the prostheses or the opposing teeth if the surface glaze wears off.
Regular review appointments and individualised maintenance are suggested to monitor the integrity of the prostheses, the condition of the abutment teeth and identify any complications at an early stage.
Monolithic translucent zirconia restorations may offer improved aesthetics, minimal tooth reduction and elimination of ceramic chipping compared to traditional zirconia cores and conventional metal restorations.
However, there is limited evidence on the survival of monolithic translucent zirconia restorations. Preliminary outcomes suggest promising results, but longer observation periods are necessary as the use of monolithic translucent zirconia increases.
The authors would like to thank Alaa Abou Hassan (dental technician, Ceramic Studios Ltd, London) for the ceramic work; and Kali Ranshi (specialty registrar in restorative dentistry, The Royal London Dental Hospital and Queen Mary University of London, Barts and the London School of Medicine and Dentistry, London, UK) for her contribution in the second clinical case towards the completion of the definitive restorations of the
Buser D, Halbritter S, Hart C, et al (2009) Early implant placement with simultaneous guided bone regeneration following single-tooth extraction in the esthetic zone: 12-month results of a prospective study with 20 consecutive patients. J Periodontol 80: 152-162
Carames J, Tovar Suinaga L, Yu YC, Pérez A, Kang M (2015) Clinical Advantages and Limitations of Monolithic Zirconia Restorations Full Arch Implant Supported Reconstruction: Case Series. Int J Dent 2015: 392496
Cardelli P, Manobianco FP, Serafini N, Murmura G, Beuer F (2015) Full-Arch, Implant-Supported Monolithic Zirconia Rehabilitations: Pilot Clinical Evaluation of Wear Against Natural or Composite Teeth. J Prosthodont 25(8): 629-633
Chen ST, Beagle J, Jensen SS, et al (2009) Consensus statements and recommended clinical procedures regarding surgical techniques. Int J Oral Maxillofac Implants 24: 272-278
Conrad HJ, Seong WJ, Pesun IJ (2007) Current ceramic materials and systems with clinical recommendations: a systematic review. J Prosthet Dent 98(5): 389-404
Dawson A, Chen S, Buser D, et al (2009) The SAC Classification in implant dentistry. Quintessence Publishing Go Ltd p4-6, 15-17, 21-25
Gadhia K, McDonald S, Arkutu N, Malik K (2012) Amelogenesis imperfecta: an introduction. Br Dent J 212(8): 377-9
Goodacre CJ, Campagni WV, Aquilino SA (2001) Tooth preparations for complete crowns: an art form based on scientific principles. J Prosthet Dent 85(4): 363-76
Guazzato M, Albakry M, Ringer SP, Swain MV (2004a) Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part I. Pressable and alumina glass-infiltrated ceramics. Dent Mater 20(5): 441-8
Guazzato M, Albakry M, Ringer SP, Swain MV (2004b) Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part II. Zirconia-based dental ceramics. Dent Mater 20(5): 449-56
Hämmerle CH, Chen ST, Wilson TG (2004) Consensus statements and recommended clinical procedures regarding the placement of implants in extraction sockets. Int J Oral Maxillofac Implants 19: 26-28
Harianawala HH, Kheur MG, Apte SK, Kale BB, Sethi TS, Kheur SM (2014) Comparative analysis of transmittance for different types of commercially available zirconia and lithium disilicate materials. J Adv Prosthodont 6(6): 456-61
Heffernan MJ, Aquilino SA, Diaz-Arnold AM, Haselton DR, Stanford CM, Vargas MA (2002) Relative translucency of six all-ceramic systems. Part II: core and veneer materials. J Prosthet Dent 88(1): 10-5
Jemt T (1999) Restoring the gingival contour by means of provisional resin crowns after single-implant treatment. Int J Periodontics Restorative Dent 19: 20-29
Johansson C, Kmet G, Rivera J, Larsson C, Vult Von Steyern P (2014) Fracture strength of monolithic all-ceramic crowns made of high translucent yttrium oxide-stabilized zirconium dioxide compared to porcelain-veneered crowns and lithium disilicate crowns. Acta Odontol Scand 72(2): 145-53
Jung YS, Lee JW, Choi YJ, Ahn JS, Shin SW, Huh JB (2010) A study on the in-vitro wear of the natural tooth structure by opposing zirconia or dental porcelain. J Adv Prosthodont 2(3): 111-5
Kapos T, Evans C (2014). CAD/CAM technology for implant abutments, crowns, and superstructures. Int J Oral Maxillofac Implants 29: 117-136
Larsson C, Wennerberg A (2014) The clinical success of zirconia-based crowns: a systematic review. Int J Prosthodont 27(1): 33-43
Le M, Papia E, Larsson C (2015) The clinical success of tooth and implant-supported zirconia-based fixed dental prostheses. A systematic review. J Oral Rehabil 42(6): 467-80
Lewis S, Parel S, Faulkner R (1995) Provisional implant-supported fixed restorations. Int J Oral Maxillofac Implants 10: 319-325
Malik K, Gadhia K, Arkutu N, McDonald S, Blair F (2012) The interdisciplinary management of patients with amelogenesis imperfecta – restorative dentistry. Br Dent J 212(11): 537-42
Martin W, Lewis E, Nicol A (2009). Local risk factors for implant therapy. Int J Oral Maxillofac Implants 24(Suppl): 28-38
Mehl C, Harder S, Wolfart M, et al (2008) Retrievability of implant-retained crowns following cementation. Clin Oral Implants Res 19: 1304-1311
Mericske-Stern RD, Taylor TD, Belser U (2000) Management of the edentulous patient. Clinical Oral Implants Research 11: 108-125
Moscovitch MS, Saba S (1996) The use of a provisional restoration in implant dentistry: a clinical report. Int J Oral Maxillofac Implants 11: 395-399
Moscovitch M (2015) Consecutive case series of monolithic and minimally veneered zirconia restorations on teeth and implants: up to 68 months. Int J Periodontics Restorative Dent 35(3): 315-23
Mundhe K, Jain V, Pruthi G, Shah N (2015) Clinical study to evaluate the wear of natural enamel antagonist to zirconia and metal ceramic crowns. J Prosthet Dent 114(3): 358-63
Nakamura K, Harada A, Inagaki R, Kanno T, Niwano Y, Milleding P, Örtengren U (2015) Fracture resistance of monolithic zirconia molar crowns with reduced thickness. Acta Odontol Scand 30: 1-7
Pjetursson BE, Sailer I, Makarov NA, Zwahlen M, Thoma DS (2015) All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part II: Multiple-unit FDPs. Dent Mater 31(6): 624-39
Preis V, Schmalzbauer M, Bougeard D, Schneider-Feyrer S, Rosentritt M (2015) Surface properties of monolithic zirconia after dental adjustment treatments and in vitro wear simulation. J Dent 43(1): 133-9
Rinke S, Fischer C (2013) Range of indications for translucent zirconia modifications: clinical and technical aspects. Quintessence Int 44(8): 557-66
Rosentritt M, Preis V, Behr M, Hahnel S, Handel G, Kolbeck C (2012) Two-body wear of dental porcelain and substructure oxide ceramics. Clin Oral Investig 16(3): 935-43
Sailer I, Fehér A, Filser F, Gauckler LJ, Lüthy H, Hämmerle CH (2007) Five-year clinical results of zirconia frameworks for posterior fixed partial dentures. Int J Prosthodont 20(4): 383-8
Sailer I, Makarov NA, Thoma DS, Zwahlen M, Pjetursson BE (2015) All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs). Dent Mater 31(6): 603-23
Stawarczyk B, Ozcan M, Roos M, Trottmann A, Hämmerle CH (2011) Fracture load and failure analysis of zirconia single crowns veneered with pressed and layered ceramics after chewing simulation. Dent Mater 30: 554-62
Thompson JY, Stoner BR, Piascik JR, Smith R (2011) Adhesion/cementation to zirconia and other non-silicate ceramics: where are we now? Dent Mater 27(1): 71-82
Venezia P, Torsello F, Cavalcanti R, D’Amato S (2015) Retrospective analysis of 26 complete-arch implant-supported monolithic zirconia prostheses with feldspathic porcelain veneering limited to the facial surface. J Prosthet Dent 114(4): 506-12
Despoina Chatzistavrianou DDS MClinDent (Pros) MPros RCSEdin MFDS RCS Ed is a specialist in prosthodontics, and specialty registrar in restorative dentistry at Birmingham Dental Hospital and University of Birmingham School of Dentistry.
Shakeel Shahdad BDS MMedSc FDS RCSEd FDS (Rest Dent) RCSEd DDS is a consultant and honorary senior clinical lecturer in restorative dentistry at The Royal London Dental Hospital and Queen Mary University of London, Barts and the London School of Medicine and Dentistry.
Philip Taylor BDS (Ncle) MGDS (RCS Eng) MSc (Lond) MRD RCS (RCS Eng) FDS (RCS Edin) is a senior lecturer and honorary consultant in restorative dentistry at The Royal London Dental Hospital and Queen Mary University of London, Barts and the London School of Medicine and Dentistry.
This article was originally published in the February 2018 issue of Aesthetic Dentistry Today. Read more articles like this in Aesthetic Dentistry Today and gain three hours’ verifiable CPD with every issue. Click here to subscribe or call 01923 851 777. Get in touch via Twitter @AesDenToday or facebook.com/AesDenToday.