The Material
Our Enamelux specialty ceramics team exclusively utilizes IPS e.max Press, a high strength ceramic composed of 70% lithium disilicate and 30% glass, to produce thier monolithic restorations. Although lithium disilicate is not new, it has only recently been developed with the optical properties and strength to become an attractive material for restorative dentistry. The monolithic structure simplifies everything. It eliminates the problem of relying on a bond between a core and porcelain. Most importantly it gives you a much stronger (fracture resistant) material than conventional porcelain on load bearing occlusal surfaces.
High Flexural Strength
The overall strength of our restorations begins with the thickness of the material. Where other conventional restorations have a core layer plus a veneering porcelain layer, our team produces a full-contour restoration of single, high-strength ceramic. The flexural strength of lithium disilicate vs. veneering porcelain is approximately 4:1. In other words, in the mouth at the all-important point of impact, the material absorbing the force is at least four times stronger with lithium disilicate than veneering porcelain.
Unsurpassed Fracture Resistance
As a welcome solution to chip-prone veneering porcelains, lithium disilicate has proven itself to be highly resistant to crack formation and propagation. In a clinical fatigue wear study of ceramic materials, lithium disilicate out performed them all. It was reported that while other ceramics failed, lithium disilicate “showed no cracks with increasing wear cycles,” and led to the conclusion that “the crystalline phases in the ceramic materials may act as crack stoppers to prevent crack propagation.”1
An independent study of mouth motion fatigue and durability found more positive results for lithium disilicate. In chewing simulations lithium disilicate was found to be “the most robust ceramic system tested to date,”2 greatly outperforming a zirconia-supported restoration by having no failures for the duration of the test.
Biocompatible
As a biocompatible material lithium disilicate also shines. In a cytotoxicity study it was proven to be comparable to, or better than, other commonly used restorative materials.3 Wear of the opposing enamel by lithium disilicate was tested by Oregon Health and Science University simulating five years worth of wear. Procera®, leucite-reinforced glass-ceramic, and even enamel
had a higher wear than lithium disilicate.4
Metal-Free Esthetics
Lithium disilicate rivals the beauty of the best metal-free materials available. Its optical properties are comparable to Empress® and layered zirconia.
References
- Brackett, MG., Lockwood, PE., Messer, RL., Lewis, JB., Bouillaguet, S. & Wataha, JC., et. al., (2007). In vitro cytotoxic response to lithium disilicate dental ceramics. Dental Materials, 24(4), 450-456.
- Etman, M.K., DDS, MSc, MMedSc, PhD., et. al.,(2009). Confocal examination of subsurface cracking in ceramic materials. Journal of Prosthodontics, 18(7), 550-559.
- Guess, PC., Silva, N., Thompson, VP., & Zavanelli, R., et. al., (2009). Mouth motion fatigue and durability study. New York University.
- Sorensen, JA., et. al., (1999). Wear of enamel against dental ceramics. Journal of Dental Research, 78(909).
- Ivoclar Vivadent (2009). Figure 1, Figure 2, & Figure 3.