Home › Forums › Labs & technology › The Science Behind Lithium Disilicate: A Metal-Free Alternative › The Science Behind Lithium Disilicate: A Metal-Free Alternative
PHYSICAL AND CLINICAL PROPERTIES OF LITHIUM DISILICATE
In vitro testing has included mechanical testing of strength using static load with a universal testing machine, subcritical eccentric loading using a chewing simulator (Willytec), and a long-time cyclic loading with a chewing simulator (eGo). The results of these tests demonstrate that:
Regardless of the in vitro test performed, in comparison to various restorative dental material for crowns (eg, leucite glass ceramic, metal ceramic, zirconia), the lithium disilicate material demonstrates superior results.
To ensure maximum success using the lithium disilicate material, it is important to consider the minimum thickness of the lithium disilicate.
The strength of the ceramic material is about 80 to 100 MPa for metal ceramics, approximately 100 MPa for veneered zirconia, and 150 to 160 MPa for leucite glass ceramic. However, for the pressed lithium disilicate (IPS e.max Press LT and HT), the strength is in the range of 360 MPa to 400 MPa (Table 1).
The pressable lithium disilicate material is indicated for inlays, onlays, thin veneers, veneers, partial crowns, anterior and posterior crowns, 3-unit anterior bridges, 3-unit premolar bridges, telescope primary crowns, and implant restorations.3-5 In some cases, minimal tooth preparation is desired (eg, thin veneers), and lithium disilicate (IPS e.max [Ivoclar Vivadent]) enables laboratories to press restorations as thin as 0.3 mm while still ensuring a strength of 400 MPa. If sufficient space is available (eg, retrusion of a tooth), no preparation is required.
Lithium disilicate is emerging as a restorative material of choice for single unit indirect restorations. Lithium disilicate increasingly is being integrated into the North American and Western European dental practices. Not only is lithium disilicate strong, but it is very versatile and lifelike. It comes in many translucencies and can be layered to maximize aesthetics in select cases. The disilicate materials (IPS e.max Press and IPS e.max CAD) maximize these benefits for laboratories and dentists.
We have witnessed the many benefits of lithium disilicate and believe that it is now one of the best restorative materials available today for single unit indirect restorations. Lithium disilicate material (IPS e.max Press and IPS e.max CAD [Ivoclar Vivadent]) has been in clinical trials for the last 4 years with adhesive and self-adhesive/conventional cementation, and the results have been very positive. We continue to complete both in vivo and in vitro testing to enhance the material’s performance and maximize its use
clinically.
References
Fabianelli A, Goracci C, Bertelli E, et al. A clinical trial of Empress II porcelain inlays luted to vital teeth with a dual-curing adhesive system and a self-curing resin cement. J Adhes Dent. 2006;8:427-431.
Deany IL. Recent advances in ceramics for dentistry. Crit Rev Oral Biol Med. 1996;7:134-143.
Sorensen JA, Cruz M, Mito WT, et al. A clinical investigation on three-unit fixed partial dentures fabricated with a lithium disilicate glass-ceramic. Pract Periodontics Aesthet Dent. 1999;11:95-106.
Höland W, Schweiger M, Frank M, et al. A comparison of the microstructure and properties of the IPS Empress 2 and the IPS Empress glass-ceramics. J Biomed Mater Res. 2000;53:297-303.
Kheradmandan S, Koutayas SO, Bernhard M, et al. Fracture strength of four different types of anterior 3-unit bridges after thermo-mechanical fatigue in the dual-axis chewing simulator. J Oral Rehabil. 2001;28:361-369.
Dr. Tysowsky is assistant clinical professor at the State University of New York at Buffalo, School of Dental Medicine, and is a Fellow of the American College of Dentistry. Dr. Tysowsky earned a DDS degree from the University of Minnesota, School of Dentistry, and a Masters of Public Health from Minnesota’s School of Public Health. He also completed a General Practice Residency at St. Francis Medical Center/University of Connecticut. He has published and lectured extensively throughout North America and Europe on the application of contemporary materials. He can be reached at george.tysowsky@ivoclarvivadent.us .