Today’s patients are requesting zirconia and porcelain crowns over metal-based crowns because both zirconia and porcelain restorations provide strength and lifelike esthetics. Since the introduction of milled zirconia restorations, patients have been increasingly requesting zirconia as an alternative to porcelain-fused-to-metal (PFM) restorations. Many myths exist surrounding the use of zirconia in dental restorations. This article debunks the myths concerning zirconia to ensure that dentists and technicians understand the differences between the materials available for restorations.
The number of Zirconia crowns fabricated annually now exceeds PFM crowns. With this trend likely to continue, it is crucial to know how best to place zirconia crowns. Often, the fit and appearance of a crown can be enhanced by making a few simple changes.
Initially, porcelain fused to metal (PFMs) restorations were the clinician’s standard choice of material, because they offered reliable treatment outcomes for the patient.
However, the opaque porcelain used to mask the metal substructure, particularly in the cervical third, frequently causes a light gray appearance at the cervical margin. The effect can worsen after a few years if gingival recession occurs. Now, the demand for increased aesthetics and more cosmetically pleasing restorations has risen exponentially, corresponding with a significant fall in demand for PFMs. PFMs have been replaced with more clinically and aesthetically acceptable all-ceramic restorations, the most popular of which is zirconia.
Increasingly, patients are demanding dental restorations that provide excellent aesthetics and functionality. Most ceramic restorations can meet these needs, and there are many different types on the market. Achieving a successful restoration depends on the clinician’s ability to select the appropriate material and follow the right preparation and cementation protocols. Selection should be based on the ceramic’s physical properties, which include fracture resistance, strength, wear resistance, and long-term durability. One of the most popular materials is zirconia. Modern zirconia is very different from its original bone-white incarnation.
The name zirconium is derived from the Arabic word “Zargun,” or golden in color, which is further derived from the Persian words “zar” for gold and “gun” for color. Zirconium is a naturally occurring element with an atomic number of 40 and is a transitional metal found in nature as the mineral Zircon. It is purified to Zirconium, a silver-colored metal that is corrosion-resistant and has properties like titanium. When combined with oxygen, it forms zirconia, a strong and highly biocompatible ceramic. Zirconium was initially discovered in the 18th century.
The introduction of stronger and more durable ceramics over the past few years has greatly increased the clinician’s choice of materials when fabricating an all-ceramic three unit bridge. The latest generation of zirconia is suitable for three unit bridges and can restore teeth anywhere in the mouth, and IPS e.max is suitable for anterior teeth.
Patient demand for dental restorations with a natural esthetic has increased considerably over the past few decades. This is partially due to greater interest in and awareness of cosmetic dentistry. For many years, clinicians used PFM crowns and bridges to provide patients with durable, long-lasting restorations that offered reasonable esthetics. However, although still a popular option, the opacity of the PFM materials cannot always satisfy esthetic demands.
A zirconia screw-retained bridge is a popular choice for clinicians who wish to provide patients with the most ideal esthetics. This type of restoration offers several advantages. One of the most appealing qualities of this bridge is its easy retrievability. An easily retrievable restoration is a good solution if the patient is likely to require regular maintenance or removal of the bridge for professional cleaning. Additionally, zirconia attracts less plaque, making it easier for the patient to maintain good oral hygiene and healthy implants. Zirconia screw-retained bridges are CADCAM designed and milled, which eliminates casting distortion and offers a predictable, precision-fitting appliance.
Porcelain-fused-to-metal crowns (PFMs) have been successfully used for many years, providing clinicians with reliable, esthetically pleasing, and long-lasting restorations. However, over the past few years, an increasing number of clinicians are choosing zirconia restorations. The number of PFM crowns requested by clinicians is lower compared with all-ceramic and zirconia restorations. Some dentists use zirconia or all-ceramic restorations almost exclusively, particularly when restoring only a single unit. The switch from one material to another has been relatively quick, so there is little long-term research into the reliability of zirconia restorations. By comparison, PFMs have been used successfully for over 60 years, and their durability has been extensively evaluated.
Titanium dental implants have been used for decades; it’s widely regarded as the ideal choice for many reasons. Although titanium dental implants have proven to give good long-term clinical outcomes in terms of functional success and rigid fixation, complications due to soft tissue recession are widespread. Using zirconia abutments can potentially minimise soft tissue recession and will hide the metal colour of the titanium, but over the past few years, several new zirconia dental implant systems have been introduced onto the market. Initial clinical studies into zirconia implants look promising, but more research is needed, particularly in the long term effects of these systems. Clinicians may also require a better understanding of the potential technical challenges of using this material to reduce the possibility of mechanical failure of zirconia implants.