November 2013, Volume 9, Issue 11
Published by AEGIS Communications
Replacing Restorations Using Pressed Lithium Disilicate
Esthetics, durability, and functionality anywhere in the mouth
All-ceramic restorations have long been considered the standard of care for restoring anterior dentition. Until the late 1990s, however, it was common practice to place cast gold restorations when patients presented at the dental practice with damaged or diseased posterior teeth. In the posterior regions of the mouth, where restorative work needed to have good fit, durability, clinical longevity, and a low incidence of allergy, cast gold was historically the material of choice.1-3 Today’s patients, however, being more educated about the available options, want metal-free solutions to fulfill their restorative requirements regardless of position within the mouth. In addition to simply wanting functional, painless restorative process, patients want the most esthetically pleasing solutions possible.
Advancements in ceramic material science have enabled the development of lithium disilicate glass ceramic (IPS e.max® Press, Ivoclar Vivadent, www.ivoclarvivident.us). This unique glass ceramic formulation is comparable to cast gold in fit, durability, and clinical longevity, but also exhibits optical properties similar to those of natural teeth. IPS e.max Press consists of approximately 70% needle-like lithium disilicate crystals in a glassy matrix. This material demonstrates a flexural strength of 400 MPa for exceptional wear resistance, a low refractive index for optimal translucency that mimics natural teeth,4 and can be adhesively bonded or traditionally cemented.5,6 These characteristics allow clinicians to confidently place lithium disilicate IPS e.max Press restorations anywhere in the oral cavity, as demonstrated the following case presentation.
A 48-year-old male patient presented with failing cast gold restorations that were placed 20 years earlier. At that time, gold restorations were the best option in terms of fit and durability. However, over time they became worn.
The patient exhibited a fracture on tooth No. 5, tooth No. 3 was broken, and he had an overall loss of vertical dimension due to bruxism (Figure 1 through Figure 3). At the same time, the patient opted to restore his worn anterior dentition to correct the wear and produce a more esthetic smile. A treatment plan was discussed with the patient that involved replacing the cast gold restorations with IPS e.max Press lithium disilicate crowns due to their strength, durability, and esthetics.
A diagnostic wax-up of the patient’s proposed restorations was made (Figure 4 through Figure 6). The patient’s teeth were prepared (Figure 7), and a clear, vacuum shell was molded on the diagnostic wax-up for creating the temporary crowns for the patient. The vacuum shell was placed in the patient’s mouth to verify fit (Figure 8), after which the provisional restorations were made. The patient wore the temporaries while the permanent crowns were being fabricated (Figure 9 and Figure 10).
The diagnostic wax-up models that were used to produce the temporary restorations were also used to create the matrices for the definitive crowns. The wax was sprued, invested, and burned out. It was then pressed with the appropriate IPS e.max ingots into full-contour form. This created the basis not only for the anterior restorations that would be subsequently cutback and layered, but also for the posterior restorations that would be simply characterized in their monolithic form.
The full-contour anterior veneers were then cut back slightly on the incisal portion to allow room for artistic modification (Figure 11 and Figure 12). Stains and glaze paste were then applied to the full-contour veneers to create natural-looking surface and internal effects. Shade 1 was applied to the cervical regions to enhance the chroma of the restorations and Essence 1 (white), Essence 4 (copper), Essence 16 (profundo), and Essence 2 (creme), were applied to the incisal third to create a more natural internal incisal effect (Figure 13).
Next, a series of IPS e.max® Ceram (Ivoclar Vivadent) powders were added to complete the incisal characterizations. No transparent incisal ceramic was used. To better control the value of the restorations, Enamel Opal shades EO1 and EO4 were blended and applied, in addition to Transpa Blue, Inter Incisal White-blue, Incisal Edge, and Dentine A1. The crowns were fired according to the manufacturer’s instructions, contoured, and glazed.
Stains and glaze were applied and fired to the posterior restorations to create subtle characterizations as well as to blend the final shade to that achieved in the layered anterior restorations. By homogenously bonding to the surface of the restorations, the glazing process not only provides a sealed, sanitary surface, but also imparts strength to the final restoration. Once stained and glazed, the finished anterior and posterior crowns were placed on the solid model (Figure 14 through Figure 16).
The temporary restorations were removed and the preparations were cleaned. The final restorations were tried in, then cleaned with Ivoclean (Ivoclar Vivadent). The crowns were loaded with Variolink® luting composite (Ivoclar Vivadent), seated onto the preparations, and light cured according to the manufacturer’s instructions. All excess cement was removed (Figure 17 through Figure 19). IPS e.max Press lithium disilicate veneers (Ivoclar Vivadent) were placed on teeth No. 22 through No. 27, and a NobelActive™ implant (Nobel Biocare, www.nobelbiocare.com) was inserted for tooth No. 3.
Twenty days after cementation, the patient was examined at a recall appointment. He had no discomfort or sensitivity, and the restorations displayed remarkably life-like esthetics, fit, and function (Figure 20 through Figure 22).
By using a high-strength yet highly esthetic material such as IPS e.max Press lithium disilicate, the ceramist for this case was able to realize the esthetic goals of the patient while providing restorations that, unlike the previously placed cast gold, will maintain their shape and functionality long term.6
The author would like to acknowledge the skills and expertise of Juan D. Cardenas, DDS. Dr. Cardenas holds a private practice specializing in prosthodontics in Miami, Florida.
1. Christensen GJ. The coming demise of the cast gold restoration? J Am Dent Assoc. 1996;127(8):1233-1236.
2. Donovan T, Simonsen RJ, Guertin G, Tucker RV. Retrospective clinical evaluation of 1,314 cast gold restorations in service from 1 to 52 years. J Esthet Restor Dent. 2004;16(3):194-204.
3. Ahlgren C, Ahnlide I, Björkner B, et al. Contact allergy to gold is correlated to dental gold. Acta Derm Venereol. 2002;82(1):41-44.
4. Michael A, Lewis H. Repairing worn dentition with lithium-disilicate glass-ceramic. Inside Dentistry. 2011;7(3):32-36.
5. McLaren EA, Phong TC. Ceramics in dentistry–part I: classes of materials. Inside Dentistry. 2009;5(9):94-103.
6. Tysowsky GW. The science behind lithium disilicate: a metal-free alternative. Dent Today. 2009;28(3):112-113.
About the Author
Rafael Santrich, CDT
President and Owner
VM Lab Technologies