Ceramics without metal (zirconium)
Strength, low weight and high corrosion resistance are the advantages of titanium implants used on daily bases in dental surgeries. The zirconium-based materials are increasingly replacing conventional materials frequently used for crowns and bridges in metal ceramics. This solution responds to the demands of aesthetic results at higher levels, the preference for non-metallic materials.
The advantages of zirconium are:
- Excellent mechanical characteristics and resistance
- Excellent aesthetics: natural result of ceramic applied on zirconium
The best material for the manufacture of aesthetic restoration in the dental field is definitely ceramic.
We must first make a distinction between ceramic and porcelain: the term porcelain is commonly used for dental prostheses but incorrectly. For dental applications you should use the term ceramics, which differs substantially from ceramics to the almost complete absence of kaolin. To be precise we will call therefore ceramic the more aesthetic and biologically accepted material for prosthetic uses of the oral cavity.
For many decades the use of dental ceramics was matched only to precious and non-precious metals, which, with the evolution of technology and materials, have led the "fixed" prosthetic to optimal levels of aesthetics and robustness. In the last ten years some projects have appeared, developed for producing ceramic (non metal = metal free), that are limited to some prosthetic applications (single crowns and ceramic inlays) give more natural aesthetic results.
Those are ceramics created in special ovens (with the technique of "lost wax") that once coated with ceramics in low melting point (750-800 °C) give shine and natural look to crowns unattainable with any metal-ceramics and it is used especially in the anterior region where the aesthetic is essential.
The disadvantage of these ceramics is the relative fragility that does not allow their application in the case of bridges, especially in the posterior quadrants where the masticatory load far exceeds the breaking load of the ceramic material. Not being able to cover every prosthetics need, towards the end of the last century the industry (taking advantage of CAD-CAM technologies), developed and adapted a material with properties that seemed to meet the dental needs: the zirconium.
We use the word "adapt" because the pure zirconium was not the appropriate material to the denture and that is why the Y-TZP zirconia was created: tetragonal polycrystalline zirconia stabilized with yttrium oxide.