The field of dental restorations has recently witnessed an evolution in the materials and techniques used and one of the most prominent innovations was the EFZ crowns (Emax Fused to Zirconia) dental crowns. With the increasing global demand for solutions that combine high strength and natural aesthetics, these EFZ crowns have become the preferred choice in advanced dental centers, especially in Europe and Asia.
In Germany and Switzerland, the adoption of EFZ crowns is reported to be over 35% of fixed cosmetic crowns, while East Asian countries such as South Korea and Japan have seen significant growth in their use of EFZ crowns in comprehensive oral rehabilitation plans. This expansion in global acceptance reflects the growing confidence in the technology, which combines the best properties of EFZ crowns, Zirconium, and Emax to meet patients’ needs for durability and natural-looking aesthetics.
What is the EFZ (Emax Fused to Zirconia) technique?
EFZ crowns or Emax Fused to Zirconia crowns are one of the most important qualitative shifts in the world of cosmetic dentistry. This technology is one of the latest dental crown technologies, which combines two main elements from the name of this technology:
Zirconia material, which is known for its high strength, durability, and resistance to tooth fractures in addition to its natural color that resembles natural teeth, and Emax material, which is known for its beauty and transparency that mimics natural tooth enamel, providing an excellent and natural aesthetic appearance.
In EFZ crowns, zirconia is used as a solid base that gives the crown a strong support as it is able to withstand strong or intense chewing and high pressure because some materials may be subject to breakage, and a layer of Emax material is coated on the outer surface to give an aesthetic appearance very close to natural teeth in terms of color, shade and gloss, this combination in EFZ crowns allows you to get the best of both materials: strength and hardness from zirconia material and beauty from Emax material.
The difference between EFZ crowns and traditional crowns
Traditional crowns such as those that use porcelain-coated metal were in the past a popular choice due to their high durability and acceptable cost, but their appearance is often not satisfactory, especially in cases where the health of the gums and mouth deteriorates over time, where a dark line may appear at the edge, causing embarrassment and disrupting the aesthetics of the smile.
There is also Pure Zirconia, where this material, as we talked about, has strength and hardness, but of course using it alone is not an ideal option due to the lack of color contrast or transparency defect, this makes it less ideal in the front teeth in particular, while high aesthetics and transparency characterize Imax but does not withstand pressure and is prone to fractures, especially in the back teeth.
This was a precursor to combining the ideal characteristics of the previous dental crown technologies and creating the EFZ crowns, which are transparent, natural-looking, strong, and pressure-resistant in the posterior teeth, making it an excellent choice over the others because it combines the best of both worlds.
Features of EFZ crowns: The combination of power and beauty
EFZ crowns, as we talked about, combine the best features of traditional crown technologies:
- High aesthetics: Emax gives the crown the ability to appear as transparent and shiny as natural teeth, which, of course, gives excellent cosmetic results, especially on the front teeth, as these subtle visual details have a clear impact on the smile.
- Hardness and durability: Zirconia is highly resistant to impact, vigorous chewing and high pressure, making it suitable for back teeth, unlike full EMAX, which can be more fragile, thus combining aesthetics and strength in EFZ crowns.
- Color fastness: Most traditional crowns change color over time, such as when pigments are absorbed from food, while EFZ crowns maintain their natural color for long periods of time and are relatively durable.
- Excellent for oral health: Both zirconia and EMAX are non-metallic ceramic materials, meaning they are non-irritating to surrounding tissues and free of metals that may cause allergic reactions in some patients.
- Resists bacteria: The zirconia surface reduces the ability of bacteria to adhere thereby reducing the likelihood of gum infections or tooth decay in the vicinity of the crown.
The ratio of Zirconium and Emax: Why 90% hardness and 10% transparency?
A high percentage of zirconia is used to achieve a perfect balance between strength and aesthetics, because the zirconia base will form the internal structure and provide the necessary support to withstand shocks and pressure, while the outer EMAX layer is the aesthetic part that resembles a normal tooth.
How does an Emacs layer help improve lighting and natural appearance?
The EMAX layer is characterized by its high transparency as it resembles the enamel of natural teeth and this allows light to pass and reflect in a realistic way that gives the crown a real, natural and non-faded appearance, this effect increases visual harmony with neighboring teeth and reduces the contrast between the crown and the gums and thus gives a natural, homogeneous smile, and the color gradation within the material accurately resembles the color of the real tooth, which makes the crown look natural under natural or even artificial lighting.
Comparison of pure zirconium and full Emax crowns
Pure zirconium crowns are known for their high strength and excellent durability, making them an ideal choice for back teeth that are subjected to strong chewing pressure as we talked about, but they lack sufficient transparency and aesthetics which can lead to a less natural appearance, especially in the anterior areas.
Full EMAX crowns are characterized by their beauty and high transparency, which makes them ideal for the front teeth in terms of appearance, but of course they are less rigid and may not withstand great chewing forces, so composite crowns that combine Zirconium and EMAX EFZ crowns allow them to be used safely in all areas of the mouth while maintaining a natural and strong appearance at the same time.
The role of sintering and fusion technology in manufacturing
Sintering and fusion technology plays the most important role in the manufacture of EFZ crowns, where Zirconium is first sintered at a high temperature to increase its hardness and then the Emax layer is precisely added to its surface using advanced thermal fusion techniques, this process requires precise control of temperatures and layer thickness to ensure a durable adhesion without cracks, the perfect combination of the two materials produces a crown that combines high durability and natural appearance and ensures color fastness and long-term hardness.
In which cases do EFZ crowns benefit? Front or back?
EFZ crowns are an excellent choice for both anterior and posterior teeth because their design, which combines rigidity, strength, and natural aesthetics, gives them flexibility of use depending on the location of the tooth and its functional and cosmetic needs.
In the front teeth, the value of EFZ crowns is highlighted by the transparent EMAX layer that reflects light in a way similar to natural teeth, making them very suitable for cases requiring aesthetic enhancement such as stained, chipped or surface-worn teeth, and they are efficiently used in cosmetic smile restorations thanks to their ability to appear with adjacent teeth without any color or visual difference.
In posterior teeth, the zirconium core ensures high strength and durability against chewing forces and high pressure, making EFZ crowns suitable for restoring molars and teeth with fractures or severe wear, providing long life in functionally intensive areas while maintaining an acceptable level of aesthetics compared to metal or full zirconium crowns.
Do EFZ crowns withstand pressure and chewing like pure zirconium?
The EFZ technology offers excellent strength and durability thanks to the solid zirconium core as we talked about, which makes it able to withstand the pressure and chewing of the back teeth, as well as high aesthetics thanks to the transparent EMAX layer, however, it is not as strong as full pure zirconium, which is the strongest option in terms of durability and resistance to breakage in cases that require maximum rigidity such as bruxism or high pressure.
The EFZ crowns are the strongest option in terms of durability and resistance to breakage in cases that require maximum hardness such as bruxism or high pressure, so EFZ crowns are an option that combines good performance, strength and aesthetic appearance without reaching the level of strength offered by full zirconium.
When are EFZ crowns recommended?
The situations in which EFZ crowns are recommended are many and include:
- When you need high rigidity with excellent aesthetics
- In the front teeth that appear when you smile, and need a natural look
- In the back teeth that are subjected to high chewing force
- After a root canal treatment, to protect the tooth from breaking
- In cases of dental implants, EFZ crowns may be needed to cover the implant aesthetically and durably
- When there is wear and tear on the teeth due to stress or aging
- For people who suffer from nocturnal bruxism
- In cases where the patient refuses or is allergic to metal crowns, EFZ crowns are needed
- When regular Emax crowns are not enough in terms of strength, zirconia is supported by EFZ crowns
- To achieve transparency and an appearance close to natural teeth with supportive strength on the inside
- When a balance between function and cosmetic appearance is needed, we use EFZ crowns
- When you want a crown that will last for years without changing color or shape
- For people who demand high-quality cosmetic dental solutions
- After the completion of clear braces, EFZ crowns may be used to improve the appearance of weak or decayed teeth and achieve a complete cosmetic result
EFZ Crowns manufacturing and installation stages
EFZ crowns go through several precise stages, starting with tooth preparation and taking measurements, and ending with the crown design and placement in the mouth to ensure strength and a natural appearance. The stages of EPZ crowns, in order:
Diagnosing the condition and determining the need for a crown
The dentist begins by examining a tooth that has been fractured, eroded or root canalized to determine whether or not it needs full coverage through EPZ crowns. Dental x-rays are taken and the condition of the gums and supporting bone are assessed before the final decision is made. The choice of the appropriate crown depends on the location of the tooth, occlusion and cosmetic factors. This evaluation is essential to ensure the success of the crown and the long-term protection of the tooth.
Preparing the tooth to receive the crown
A small portion of the tooth’s surface is filed from all sides to provide the space needed to place the crown without putting pressure on the gums or neighboring teeth, as the preparation takes into account preserving as much of the natural tooth size as possible to ensure a strong support for the crown. A temporary crown is often placed to protect the tooth until the final crown is completed.
Taking accurate tooth measurements
A traditional impression is taken using special materials or through digital devices where the entire mouth is scanned to obtain an accurate model, this step ensures that the crown is made with accurate and correct measurements with no gaps or deviations.
Designing a crown core in the lab
The inner part of the crown is designed from solid zirconia, where its dimensions and shape are determined with high precision to suit the natural tooth, as this part gives the crown the necessary strength and durability to resist pressure during chewing, and this design is comprehensive and takes into account the shape of the neighboring teeth. A 3D design program is used to accurately plan the crown.
Sculpting a Zirconian heart from a solid block
The inner part of the crown is molded from zirconia, as we said, using precise devices and carving according to the design created in the program to ensure conformity, as any error in this step causes instability or issues later, so it is performed with advanced devices under supervision and scrutiny.
Putting the heart in a special oven to strengthen it
The zircon core is placed in a kiln at a very high temperature, which gives it the high hardness that makes it withstand chewing and pressure on a daily basis, and the duration of burning and heat control are two factors that directly affect the quality and transparency of the material. After burning, the core comes out with a white, opaque color that is ready to receive the cosmetic layer. This stage ensures a strong inner core that does not break easily.
Preparing the outer cosmetic layer
After the inner part is cooled, a transparent porcelain layer is prepared and placed over it to give the crown its natural color and shape similar to the adjacent natural teeth, as this layer is responsible for the beauty of the crown and its integration with the natural teeth in terms of color and luster, and the thickness of this layer can be adjusted according to the location of the tooth and the extent of the need for aesthetics.
Gluing the cosmetic layer to the solid core
In this step, the outer layer and the zirconia core are precisely fused by burning at certain temperatures or using special adhesives specialized for this type of crowns, the adhesive is distributed evenly to avoid bubbles or poor adhesion, and the good fusion between the two layers gives the crown the final strength and aesthetic and natural appearance. A mistake at this stage affects the stability of the crown or leads to peeling of the outer layer after the EFZ crowns are finished.
Color and polish the finished crown
EFZ crowns are colored to match the patient’s natural teeth, then the surface of the crown is smoothed and polished to look exactly like the natural tooth, where special brushes and colors are used to become like the natural shade of the teeth, after coloring, the crown is returned to the oven to fix the color and then polished by hand.
Send the crown to the doctor to try on the patient
The dentist will try the crown on in the patient’s mouth to ensure it fits properly in terms of size, occlusion, color, and comfort. Minor adjustments may be made before the final placement. The dentist will also ensure that the crown does not put pressure on the gums or opposing teeth.
Permanently stabilize the crown inside the mouth
After ensuring the success of all EFZ crowns, the tooth is thoroughly cleaned and the crown is fixed with a very strong adhesive and dried with a special light source to ensure its stability, and the patient is given instructions to take care of the crown after installation.
Are there any drawbacks or feedback on using EFZ?
- The cosmetic layer may peel off: The outer layer may crack or separate from the hard core, especially in cases of extreme pressure on the teeth.
- Requires greater tooth preparation: The thickening of the crown due to the presence of inner and outer layers requires the removal of a greater amount of tooth structure.
- Requires high precision in fitting: Any flaw in design or fit can lead to issues with fit or comfort.
- Difficult to repair: If the crown is broken or chipped, it is often difficult to repair and replace the entire crown.
- High cost: Compared to some of the other types, this type requires an advanced and experienced lab, which increases the cost.
Overall, EFZ crowns represent a paradigm shift in the field of dentistry thanks to their ability to combine high durability with an attractive natural appearance. They provide a solution for patients looking for long-lasting results without compromising on aesthetics, and with the development of manufacturing techniques and high precision in their design, these crowns have become a reliable option in many clinical situations. Offering a modern alternative that meets the needs of patients in terms of performance, comfort, and appearance, EFZ crowns are a step forward in the world of modern dentistry.
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