REVIEW

 

Overview of Lithium Disilicate as a restorative material in dentistry

 

 

G Streit^I; LM Sykes^II

^IBChD (Pret), MSc(Dent) (UWC), PG Dip Aesthetics (Pret) ,PDD Interceptive Orthodontics (UWC), PG Dip Practice Management (Pret), PG Dip Paedodontics (Pret), PG Dip Prosthodontics (Pret) Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, University of Pretoria. ORCID: 0000-0003-2251-7169
^IIBSc, BDS, MDent, Dip Research Ethcs (IRENSA); Dip ESMEA (Univ Dundee), DipOdont (Forensic Odontology), Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa, ORCID Number: 0000-0002-2002-6238; 3

Correspondence

 

 

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ABSTRACT

Lithium disilicate was first introduced to the dental field as an indirect restorative material in 1998. It was marketed under the name IPS Empress 2, and was intended for use with press technology. It was later replaced by modified versions including IPs e.max® Press and IPS e.max® CAD. Newer versions have since emerged, namely Amber Mill GC Initial and CEREC Tesseratwo. The latter has part crystal composition of lithium disilicate, embedded in a glassy zirconia matrix. The CAD version is provided in a meta-silicate state, characterised by 40% platelet-shaped lithium meta-silicate crystals and a glassy matrix that is bluish in colour. To obtain the desired lithium disilicate structure and tooth shades, a process of crystallization is required. This involves firing at 840 °C, for 25 minutes. The resulting glass-ceramic material has the benefit of providing maximum aesthetic translucency along with good fracture resistance of about 2MPa, and mechanical strength of 360MPa.
Developments in the all-ceramic dental materials have led to improvements in their physical properties and aesthetic appeal, leading to a substantial increase in their clinical use. This paper present a review of lithium disilicate with particular reference to its chemical composition, aesthetic versatility, and durability for use in crowns, veneers, and implant retained restorations. It also covers the recommended techniques prescribed to ensure predictable bonding and cementation. An electronic literature search on the use of lithium disilicate in dentistry was carried out using EBSCOhost search engine. This included all papers relating to its use for conventional veneers, crowns and bridge work, for CAD/CAM restorations, dentine bonding procedures and luting agents. It covered all papers published in peer reviewed journals from 1988 to 2021. The review indicates that lithium disilicate can be a useful and versatile material in dentistry providing it is handled correctly and the recommended tooth and restoration surface preparations and bonding procedures are carried out. The latter involves tooth etching and silane treatment of the fitting surfaces of restorations prior to cementation to improve adhesion and fracture resistance.

Keywords: Lithium distillate, Li₂O₅Si₂, dentine bonding, Ceramic; e.max®; Microstructure Glass ceramic

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LITERATURE REVIEW

The use of ceramics in dentistry dates back to the 19th century, with continued developments and improvements being made in terms of material properties and bonding techniques and materials. The dental ceramics that are currently used include metal-based and metal-free ceramics, layering and press ceramics, and analogue and digitally processed ceramics.¹

The all-ceramic IPS e.max® system which is a lithium disilicate composition was launched in 2005. This material set new standards in terms of its optical and mechanical performance. It was the first modular, fully integrated all-ceramic system of its kind on the market offering excellent aesthetics, different levels of translucency, and increased strength when used in both press systems and with CAD/CAM technology. This has allowed it to be used for a broad spectrum of dental restoration.^1,2

Lithium disilicate (Li₂O₅Si₂) is a glassy ceramic with an average flexural strength of 400Mpa and a favourable translucency, making it suitable for both anterior and posterior use.^3,4 Press ceramics have been on the market for almost 25 years and are now also available in the form of pressable multi-coloured ingots for highly aesthetic monolithic restorations.^1,2

Li₂O₅Si₂ has many advantages over the traditional metal materials, macromolecule materials, and older ceramics. These include high mechanical and flexural strength, good wear resistance and excellent aesthetics.^5-11 However, despite the advances in adhesive dentistry, long-lasting bonds between indirect restorations and dentin has remained a challenge.¹² Retrospective studies on success rates of Li₂O₅Si₂ ceramic restorations from between three to ten years of follow up, showed survival rates (i.e. restorations that had remained in place without complications) of over 95%, with the monolithic crowns having less reported structural problems than layered crowns.^13-16

Many studies revealed that a significant part of the restoration success depended on the dental luting technique¹⁷ and treatment of the Atting surface.^18-21 Adhesive cements were shown to help improve retention and fracture resistance²², While the marginal discrepancy was also affected by the luting agent, the fabrication technique, and the ceramic system used.^16,23

Satisfactory bond union relies on the restoration being close-fitting, but is further aided by surface modification (surface area enlargement), achieved via etching with hydrofluoric acid (HF). This etching creates a surface roughness that aids mechanical interlocking of the luting substance to the treated surface. A further development in the bonding process between the resin cement and the ceramic restoration surface is the chemical bond created by surface silinisation.²⁴'²⁵

The microstructure of Li₂O₅Si₂ features a wide bimodal grain size distribution with large rod-like crystals epitaxially grown along with the seed and small crystals nucleated from the glass powder. This unique structure has helped improve the fracture toughness and increase its flexural strength.²⁶ The coexistence of large rod-like crystals and smaller ones formed by the solid-state reaction of crystal and SiO₂ glass has improved its mechanical properties.^27-32 By controlling the in-situ growth phase via the sintering process of lithium disilicate crowns, some grains grow elongated with a high aspect ratio, thus obtaining the bimodal microstructure similar to that of fibre reinforced composites.³³ This distribution plays a role in deflection and bridging cracks to improve the flexure, strength, and adhesive properties.^22,34 However, due to its intrinsic brittleness and low defect tolerance, the fracture toughness of lithium disilicate is still far less than that of zirconia.^10-15

Etching

Various different etching regimes have been recommended by different manufacturers. These include etching the Atting surfaces of the restorations with micro brush application of either IPS Ceramic Etching Gel acid HF (4%) or VITA Ceramics etch (5%) for 20 seconds. These agents must then be thoroughly rinsed off with water and air dried. The diluted solution is treated with a neutralising powder composed of sodium and calcium carbonate (IPS Neutralizing Powder, Ivoclar Vivadent) for 5 minutes and placed in an ultrasonic bath. Ultradent recommend etching for 30 s with 35% phosphoric acid, followed by rinsing with water and drying for 5 seconds,^35,36. Ivoclar advise that IPS e.max® CAD and IPS e.max® Press restorations be etched for 20 seconds with 5% HF.³⁷ However, Shahverdi et al. found that a combination of sandblasting, HF acid treatment and silane application was the most successful regime.³⁸

On the other hand, Guilherme stated that treatments with alumina airborne-particle abrasion alone or etching with 95% HF for 30 seconds improved shear bond strength.³⁹ However, combining alumina airborne-particle abrasion with different HF etching procedures did not improve shear bond strength and HF alone was sufficient.³⁹

Dental restorations in which enamel and dentin were prepared using the total-etch method attained bonds of up to 28Mpa in enamel⁴⁰ and 13-20Mpa in dentin.⁴¹

The bonds achieved with etch and rinse systems are stronger and more predictable on enamel surfaces, while those on exposed dentin show reduced fracture resistance.^42-43 Self-etching primers offer a more simplified bonding protocol and are reported to improve bonding to the dentin, as they etch the surface and penetrate it simultaneously.^44,45 Initial studies suggest that the self-etching primers show promise in terms of improving bonding to dentin,⁴⁶ However others have noted that the bond strength mediated by the self-etch primer Monobond Etch and Prime (MEP) was lower than that of the functional silane hydrolyzed3-methacryloxypropyl trimethoxy silane (MPTMS) or Mono Bond Plus with HF technique.^47,48

Silanes

Silanes are a class of organic molecules that contain one or more silicon atoms (3-methacryloxypropyl trimethoxy silane), which act as a wetting agent and help to form covalent chemical bonds at the involved interfaces. Single-bottle silanes that are pre-hydrolysed typically consist of 1% to 5% silane in a water/ethanol solution with added acetic acid to achieve the desired pH of 4 to 5. They perform optimally if left for 5 minutes. Silane hydrolysis creates terminal hydroxyl groups on each silane molecule. These hydroxyl groups react directly with corresponding hydroxyl groups on the surface of feldspathic porcelain through the oxidation of SiO₂. A condensation polymerization reaction creates bonds between the silane and porcelain when the opposing hydroxyl groups interact with one another via hydrogen and covalent bonding.⁴⁹ Clinically, the surface of the porcelain should appear matt after silane application and drying. Once the inorganic end of the silane molecule has bonded to the porcelain, the methacrylate group can bond via free radical addition polymerization with methacrylate groups in the resin. Silica coating is not effective, or required, with Li₂O₅Si₂ because significant amounts of SiO₂ and free hydroxyl groups are already present.^4,37

Cementation

Cementation with zinc phosphate provides mechanical retention and relies heavily on the contour of the prepared tooth and close adaptation of the restoration to provide retention. Clinically this mechanical retention is considered less effective than that obtained with bonding systems.⁵⁰ Composite resin cement Rely-X Ultimate in combination with Scotch bond Universal adhesive provided equal mean removal stress as for Multilink Automix used with Multilink Primer, with both generating high crown removal of,2.9 to 3.9 MPa. These all exceeded zinc phosphate cement adherence.¹⁶

Adhesively cemented dental ceramic crowns have a superior breakage resistance compared to traditionally cemented restorations. However this may also be dependent on the thickness of all-ceramic restorations especially in veneers.^51,53 Occlusal veneers with a thickness of 0.6-1.0 mm and 1.2-1.8 mm can resist forces of up to 800 N and 1000 N respectively.^54-56 In a study by Sasse et al.,⁵² the fracture resistance of occlusal veneers made of Li₂O₅Si₂ was examined and showed that the thickness of the occlusal veneers should not fall below 0.7-1.0 mm.

Self-adhesive resin cements are used to simplify the technique due to their high viscosity and low etching capacity. The bond strength of self-adhesive resin cements is lower than that of resin cements and adhesive systems. To optimise the bond strength between cements and teeth, surface treatment with different conditioning agents have been suggested. Chlorhexidine is widely used as an antibacterial agent and has a broad antimicrobial spectrum. This solution has an inhibitory effect on the activity of MMP on dentin, which can prevent collagen collapse and the corresponding degradation and disintegration of the bond interface.

Lührs et al. and Shaflei and Memarpour verified a decrease in bond strength values of self-adhesive cements over time. When compared to conventional hydrophobic resin cements, water sorption was higher due to the acidic and hydrophilic character of the self-adhesive cements. Rely X U200 has a lower initial pH (<2) which increases its potential for demineralisation and contributes to higher bond strength if compared to Smart Cem 2. Both agents showed lower bond strength compared to conventional resin cements due to four factors: (1) acidic monomers have low etching capacity, minimising the surface demineralisation; (2) the buffering effect of the minerals present in the dentin can neutralise the pH of the cement; (3) the high viscosity of the cement hinders their penetration into the interflbrillar spaces; (4) non-removal or incomplete removal of the smear layer promotes a weakly bonded reinforced resin intermediate layer. The loss of integrity of the resin-dentin interface during function is affected by thermal, mechanical, and chemical actions. These actions are detrimental to the longevity of indirect restorations luted with resin cement.¹²

For luting Li₂O₅Si₂ crowns there are three suggested cement-adhesive combinations that may be used (RelyX Ultimate with Scotch Bond Universal, Monobond S, Multilink Automix with Multilink Primer A and B and NX3 Nexus with OptiBond XTR). All showed good retention (2.9-3.9 MPa; 387-522N) after six months. Cements using their matched dentin bonding agent as the ceramic primer were as successful as cements with a separate silane coupling agent, but self-adhesive resin cements such as U100 showed lower bond strength to dentin than RelyX ARC conventional resin cement.^16,64

 

REFERENCES

1. Ivoclar Vivadent. A brief history of a great invention. Advanced Esthetics & High Quality. 2015, August 24. https://blog.ivoclarvivadent.com/lab/en/dental-ceramics-a-brief-history-of-a-great-invention        [ Links ]

2. Barizon KT, Bergeron C, Vargas MA, Qian F, Cobb DS, Gratton DG, et al. Ceramic materials for porcelain veneers: part II. Effect of material, shade, and thickness on translucency. J Prosthet Dent. 2014;112:864-70.         [ Links ]

3. Batson ER, Cooper LF, Mendonca G. Clinical outcomes of three different crown systems with CAD/ CAM technology. J Prosthet Dent. 2014;112:770-7.         [ Links ]

4. González, ACP, Mejía, E-D. Alternatives of surface treatments for adhesion of lithium disilicate ceramics. RevistaCubana de Estomatología. 2018;55(1):59-72. http://scielo.sld.cu/pdf/est/v55n1/a07_1525.pdf        [ Links ]

5. Thieme K, Avramov I, Rüssel C. The mechanism of deceleration of nucleation and crystal growth by the small addition of transition metals to lithium disilicate glasses. Sci Rep. 2016;6:25451. doi:10.1038/ srep25451        [ Links ]

6. Gaddam A, Fernandes HR, Tulyaganov DU, Pascual MJ, Ferreira JMF. Role of manganese on the structure, crystallization and sintering of non-stoichiometric lithium disilicate glasses. RscAdv. 2014;4:13581-13592.         [ Links ]

7. Zhao T, Qin Y, Wang B, Yang J. Improved densiflcation and properties of pressureless-sintered lithium disilicate glass-ceramics. Mat SciEng A. 2015;620:399-406.         [ Links ]

8. Wang F, Gao J, Wang H, Chen J-H. Flexural strength and translucent characteristics of lithium disilicate glass-ceramics with different P2O5 content. Mater Des. 2010;31:3270-3274.         [ Links ]

9. Huang SF, Li Y, Wei SH, Huang Z, Gao W, Cao P. A novel high-strength lithium disilicate glass-ceramic featuring a highly intertwined microstructure. J Eur Ceram Soc. 2017;37:1083-1094.         [ Links ]

10. Lien W, Roberts HW, Platt JA, Vandewalle KS, Hill TJ, Chu T-MG. Microstructural evolution and physical behaviour of a lithium disilicate glass-ceramic. Dent Mater. 2015;31(8):928-940.         [ Links ]

11. Amer R, Kürklü D, Johnston W. Effect of simulated mastication on the surface roughness of three ceramic systems. J Prosthet Dent. 2015;114:260-5.         [ Links ]

12. Mobilio N, Fasiol A, Mollica F, Catapano S. Effect of different luting agents on the retention of lithium disilicate ceramic crowns. Materials. 2015;8(4):1604-1611. doi:10.3390/ma8041604        [ Links ]

13. Zhang F, Reveron H, Spies BC, Van Meerbeek B, Chevalier J. Trade-off between fracture resistance and translucency of zirconia and lithium-disilicate glass ceramics for monolithic restorations. ActaBiomater. 2019;91:24-34.         [ Links ]

14. Tinschert J, Natt G, Mautsch W, Augthun M, Spiekermann H. Fracture resistance of lithium disilicate-, alumina-, and zirconia-based three-unit fixed partial dentures: A laboratory study. Int J Prosthodont. 2001;14:231-238.         [ Links ]

15. Harada K, Raigrodski AJ, Chung K-H, Flinn BD, Dogan S, Mancl LA. A comparative evaluation of the translucency of zirconias and lithium disilicate for monolithic restorations. J Prosthet Dent. 2016;116:257-263.         [ Links ]

16. Johnson GH, Lepe X, Patterson A, Schäfer O. Simplified cementation of lithium disilicate crowns: Retention with various adhesive resin cement combinations. The Journal of Prosthetic Dentistry. 2018;119(5):826-832.         [ Links ]

17. Good ML, Orr JF, Mitchell CA. In vitro study of mean loads and modes of failure of all-ceramic crowns cemented with light-cured or dual-cured luting cement, after 1 and 30 d of storage. Eur J Oral Sci. 2008;116:83-8.         [ Links ]

18. Kern M, Sasse M, Wolfart S. Ten-year outcome of three-unit fixed dental prostheses made from monolithic lithium disilicate ceramic. J Am Dent Assoc. 2012;143:234-40.         [ Links ]

19. Amaral R, Rippe M, Oliveira BG, Cesar PF, Bottino MA, Valandro LF. Evaluation of tensile retention of Y-TZP crowns after long term ageing: Effect of the core substrate and crown surface conditioning. Oper Dent. 2014;39:619-26.         [ Links ]

20. Shahin R, Kern M. Effect of air-abrasion on the retention of zirconia ceramic crowns luted with different cements before and after artificial ageing. Dent Mater. 2010;26:922-8.         [ Links ]

21. Nagai T, Kawamoto Y, Kakehashi Y, Matsumura H. Adhesive bonding of a lithium disilicate ceramic material with resin-based luting agents. J Oral Rehabil. 2005;32:598-605.         [ Links ]

22. Wang B, Yang J, Guo R, Gao J, Yang J. Microstructure and property enhancement of silicon nitride-barium aluminium silicate composites with ß-Si3N4 seed addition. J Mater Sci. 2009;44:1351-1356.         [ Links ]

23. Baldissara P, Llukacej A, Ciocca L, Valandro FL, Scotti R. Translucency of zirconia copings made with different CAD/CAM systems. J Prothet Dent. 2010;104:6-12.         [ Links ]

24. Blatz MB, Sadan A, Kern M. Bonding to silica-based ceramics: Clinical and laboratory guidelines. Quintessence Int. 2002;25:54-62.         [ Links ]

25. Blatz MB. The long-term clinical success of all-ceramic posterior restorations. Quintessence Int. 2002;33:415-26.         [ Links ]

26. Zhao T, Lian M-M, Qin Y, Zhu J-F, Kong X-G, Yang J-F. Improved performances of lithium disilicate glass-ceramics by seed induced crystallization, Journal of Advanced Ceramics. 2021;10(3):614-626.         [ Links ]

27. Zhao T, Li AJ, Qin Y, Zhu J-F, Kong X-G, Yang J-F. Influence of SiO2 contents on the microstructure and mechanical properties of lithium disilicate glass-ceramics by reaction sintering. J Non-Cryst Solids. 2019;512:148-154.         [ Links ]

28. Zhao T, Qin Y, Zhang P, Wang B, Yang J. Highperformance, reaction sintered lithium disilicate glass-ceramics. Ceram Int. 2014;40:12449-12457.         [ Links ]

29. Hirao K, Nagaoka T, Brito ME, Kanzaki S. Microstructure control of silicon nitride by seeding with rodlike β-silicon nitride particles. J Am Ceram Soc. 1994;77:1857-1862.         [ Links ]

30. Pyzik AJ, Beaman DR. Microstructure and properties of self-reinforced silicon nitride. J Am Ceram Soc. 1993;76:2737-2744.         [ Links ]

31. Yoshizawa YI, Toriyama M, Kanzaki S. Preparation of high fracture toughness alumina sintered bodies from layer aluminium hydroxide. J Ceram SocJpn. 1998;106:1172-1177.         [ Links ]

32. Chen IW, Rosenflanz A. A tough SiAlON ceramic-based ona-Si3N4 with a whisker-like microstructure. Nature. 1997;389:701-704.         [ Links ]

33. Peillon FC, Thevenot F. Microstructural designing of silicon nitride related to toughness. J Eur Ceram Soc. 2002;22:271-278.         [ Links ]

34. Becher PF, Hsueh CH, Angelini P, Tiegs TN. Toughening behaviour in whisker-reinforced ceramic matrix composites. J Am Ceram Soc. 1988;71:1050-1061.         [ Links ]

35. Bajraktarova-Valjakova E, Grozdanov A, Guguvcevski L, Korunoska-Stevkovska V, Kapusevska B, Gigovski N, et al. Acid etching as surface treatment method for luting of glass-ceramic restorations, part 1: Acids, application protocol and etching effectiveness. Open Access Maced J Med Sci. 2018;6(3):568-573. doi:10.3889/oamjms.2018.147        [ Links ]

36. Carla VP, Mario UT, Joana SA. Surface treatment of lithium disilicate with different concentrations of hydrofluoric acid and orthophosphoric acid. 2019.         [ Links ]

37. Alex G. Preparing porcelain surfaces for optimal bonding. CompendContinEduc Dent. 2008;29(6):324-35.         [ Links ]

38. Shahverdi S, Canay S, Sahin E, Bilge A. Effects of different surface treatment methods on the bond strength of composite resin to porcelain, J Oral Rehabil. 1998;25:699-705.         [ Links ]

39. Guilherme N, Wadhwani C, Zheng C, Chung K-H. Effect of surface treatments on titanium alloy bonding to lithium disilicate glass-ceramics. The Journal of Prosthetic Dentistry. 2016;116(5):797-802.         [ Links ]

40. Kern M, Thompson VP. A simple method for universal testing of tensile bond strength. DtschZahnärztl Z. 1993;48:769-72.         [ Links ]

41. Fortin D, Swift Jr EJ, Denehy GE, Reinhardt JW. Bond strength and microleakage of current dentin adhesives. Dent Mater. 1994;10:253-8.         [ Links ]

42. Peumans M, Kanumilli P, De Munck J, Van Landuyt K, Lambrechts P, Van Meerbeek B. Clinical effectiveness of contemporary adhesives: a systematic review of current clinical trials. Dent Mater. 2005;21:864-81.         [ Links ]

43. Burke FJ. Survival rates for porcelain laminate veneers with special reference to the effect of preparation in dentin: A literature review. J EsthetRestor Dent. 2012;24(4):257-65.         [ Links ]

44. De Munck J, Van Landuyt K, Peumans M, Poitevin A, Lambrechts P, Braem M, et al. A critical review of the durability of adhesion to tooth tissue: methods and results. JDent Res. 2005;84:118-32.         [ Links ]

45. Itou K, Torii Y, Takimura T, Chikami K, Ishikawa K, Suzuki K. Effect of priming time on tensile bond strength to bovine teeth and morphologic structure of interfaces created myself-etching primers. Int J Prosthodont. 2001;14:225-30.         [ Links ]

46. Frankenberger R, Lohbauer U, Roggendorf MJ, NaumannM,Taschner M. Selective enamel etching reconsidered: better than etch-and-rinse and self-etch? J Adhes Dent. 2008;10:339-44.         [ Links ]

47. Dimitriadi M, Zinelis S, Zaflropoulou M, Silikas N, Eliades G. Self-etch silane primer: reactivity and bonding with a lithium disilicate ceramic. MDPI. 2020;13(3):641. doi:10.3390/ma13030641        [ Links ]

48. Grégoire G, Poulet P-P, Sharrock P, Destruhaut F, Tavernier B. Hydrofluoric acid etching versus self-etching glass ceramic primer: Consequences on the interface with resin cements. Oral Health and Care. 2019;4. doi:10.15761/OHC.1000169.         [ Links ]

49. Stewart GP, Jain P, Hodges J. Shear bond strength of resin cements to both ceramic and dentin. J Prosthet Dent. 2002;88:277-284.         [ Links ]

50. EvaggeliaPapia 1, Per Vult von Steyern. The bond strength between different bonding systems and densely sintered alumina with sandblasted surfaces or as produced. Swed Dent J. 2008;32(1):35-45.         [ Links ]

51. Sachdeva B, Dua P, Mangla R, Kaur H, Rana S, Butail A. Bonding efficacy of 5th,6th,7th & 8th generation bonding agents on primary teeth. IOSR-JDMS. 2018;17(3):61-66.         [ Links ]

52. Sasse M, Krummel A, Klosa K, Kern M. Influence of restoration thickness and dental bonding surface on the fracture resistance of full-coverage occlusal veneers made from lithium disilicate ceramic. Dent Mater. 2015;31:907-15.         [ Links ]

53. Lima JM, Souza AC, Anami LC, Bottino MA, Melo RM, Souza RO. Effects of thickness, processing technique, and cooling rate protocol on the flexural strength of a bilayer ceramic system. Dent Mater. 2013;29:1063-72.         [ Links ]

54. Magne P, Schlichting LH, Maia HP, Baratieri LN. In vitro fatigue resistance of CAD/CAM composite resin and ceramic posterior occlusal veneers. J Prosthet Dent. 2010;104:149-57.         [ Links ]

55. Schlichting LH, Maia HP, Baratieri LN, Magne P. Novel-design ultra-thin CAD/CAM composite resin and ceramic occlusal veneers for the treatment of severe dental erosion. JProsthet Dent. 2011;105:217-26.         [ Links ]

56. Diaz-Arnold AM, Vargas MA, Haselton DR. Current status of luting agents for fixed prosthodontics. J Prosthet Dent. 1999;81:135-41.         [ Links ]

57. Kao EC, Johnston WM. Fracture incidence on debonding of orthodontic brackets from porcelain veneer laminates. JProsthet Dent. 1991;66:631-7.         [ Links ]

58. Klosa K, Wolfart S, Lehmann F, Wenz HJ, Kern M. The effect of storage conditions, contamination modes and cleaning procedures on the resin bond strength to lithium disilicate ceramic. J Adhes Dent. 2009;11:127-35.         [ Links ]

59. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 16 years. Part III: Effect of luting agent and tooth or tooth-substitute core structure. J Prosthet Dent. 2001;86:511-9.         [ Links ]

60. McCormick JT, Rowland W, Shillingburg Jr HT, Duncanson Jr MG. Effect of luting media on the compressive strengths of two types of all-ceramic crown. Quintessence Int. 1993;24:405-8.         [ Links ]

61. Piwowarczyk A, Bender R, Ottl P, Lauer HC. The long-term bond between dual-polymerizing cementing agents and human hard dental tissue. Dent Mater. 2007;23:211-7.         [ Links ]

62. Scherrer SS, De Rijk WG, Belser UC. Fracture resistance of human enamel and three all-ceramic crown systems extracted teeth. Int J Prosthodont. 1996;9:580-5.         [ Links ]

63. Yoshinari M, Derand T. Fracture strength of all-ceramic crowns. Int J Prosthodont. 1994;7:329-38.         [ Links ]

64. Hiraishi N, Yiu C, King N, Tay F. Effect of 2% chlorhexidine on dentin micro tensile bond strengths and nanoleakage of luting cements. Journal of dentistry. 2009;37:440-8. doi:10.1016/j. jdent.2009.02.002.         [ Links ]

65. Krummel A, Garling A, Sasse M, Kern M. Influence of bonding surface and bonding methods on the fracture resistance and survival rate of full-coverage occlusal veneers made from lithium disilicate ceramic after cyclic loading. Dental Materials. 2019;35:1351-1359.         [ Links ]

66. Cardoso MV, De Almeida Neves A, Mine A, Coutinho E, Van Landuyt K, De Munck J, Van Meerbeek B. Current aspects on bonding effectiveness and stability in adhesive dentistry. Australian Dental Journal. 2011;56(1):31-44. doi:10.1111/j.1834- 7819.2011.01294.x        [ Links ]

67. McLaren EA, Hamilton J. Tips and tricks for the adhesive cementation of ceramic inlays, onlays, and veneers. Inside Dentistry. 2007;3(1), January.         [ Links ]

 

 

Correspondence:
Prof LM Sykes
Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences
University of Pretoria, Pretoria, South Africa
Email: leanne.sykes@up.ac.za

 

 

Author contributions:
1 . Günther Streit 70%;
2 . Leanne M Sykes 30%