Zirconia crowns have quickly become one of the most popular materials for dental restorations. Both patients and providers appreciate zirconia crowns for their durability, strength, translucency and natural esthetics. The key to a strong, comfortable, and esthetic crown is the proper preparation with the right product. By following careful preparation guidelines for zirconia crowns and accurately adjusting the crown prep tooth, you ensure long-term durability and comfort for your patient.
Why Tooth Prep for Crowns Matters
A careful crown prep procedure is vital for improving the patient experience and plays a vital role in providing patients with a comfortable, long-lasting restoration. There are several advantages to proper tooth prep for crowns, like:
- Creating smooth edges during tooth preparation helps reduce stress on crowns and minimizes the risk of fractures.
- Careful reduction ensures better esthetics.
- Uniform reduction during preparation helps improve the strength of the restoration.
- Digital scanners are able to read smooth and consistent preparations more accurately.
- A better preparation leads to better oral health and comfort for the patient
As a result, providers should take special care to ensure accurate measurements and careful shaping of the crown prep tooth
How To Prepare the Tooth Structure for a Zirconia Crown
For any crown, two guiding considerations are clearance and circumferential chamfer. However, the most significant factor in determining each is the type of zirconia crown used and where it will be placed. Whether you are prepping for an anterior or posterior crown will lead to a slightly different zirconia crown prep dimensions.
Crown Prep Procedure for an Anterior Zirconia Crown
Anterior crowns need an extra level of care and attention to ensure that they not only fit well but also provide the best esthetics. After all, anterior crowns are far more visible when talking or smiling.
For the most comfortable and esthetic anterior crown tooth prep, you should do the following:
- Create space for the restoration by ensuring a wall thickness with a minimum of 0.3 mm, ideally between 1.0 and 1.5 mm
- Prepare a 1.8 to 2.0 mm incisal reduction
- Create a visible and continuous circumferential chamfer
- Ensure at least a 0.5 mm reduction at the gingival margin
- Ensure the horizontal and vertical preparation have an angle of about 5 degrees
- Avoid creating a bevel on the preparation
- Ensure all incisal edges are rounded with no sharp edges
- Reduce the lingual aspect of anterior teeth to create a concave lingual
Crown Prep Procedure for a Posterior Zirconia Crown
As with preparing for an anterior crown, posterior crowns require you to focus on both clearance and circumferential chamfer. However, posterior crowns do differ slightly because the priority is strength and durability for chewing, and posterior crowns provide a different amount of space.
For durable and proper-fitting posterior crowns, you should do the following:
- Create enough space with a wall thickness at a minimum of 0.5 mm
- Prepare an occlusal reduction between 1.5 to 2 mm
- Maintain a visible and continuous circumferential chamfer
- Taper the crown prep between 4 and 8 degrees
- Create a reduction of at least 0.5 mm at the gingival margin
- Avoid creating a bevel
- Ensure that all occlusal edges are rounded with no sharp points
- Use either shoulder or Chamfer preparations for the ideal zirconia crown prep
How To Decide on the Correct Zirconia Restorations
One of the biggest benefits of zirconia is its versatility. However, this does provide you with an extra step in the decision-making process, as you will need to decide between either monolithic or layered zirconia crowns for your patient. The better choice for your patient depends on their specific needs.
Monolithic zirconia crowns are known mostly for their strength. Therefore, monolithic zirconia is the better option for:
- Restorations of posterior teeth that are important for chewing
- Patients with a high level of bruxism or grinding during their sleep
- Patients with limited occlusal clearance
Meanwhile, layered zirconia crowns are chosen more often for their more natural-looking and translucent appearance. As a result, layered zirconia is better for:
- Anterior restorations where esthetics are prioritized over chewing function
- Restorations where more clearance is available
Although layered zirconia is known as the more esthetic option, monolithic zirconia is becoming increasingly more realistic. Options like ALL-Z Plus Translucent Solid Zirconia crowns provide both the natural translucency of natural teeth and the strength of monolithic zirconia without any porcelain overlay.
Factors That Can Make Zirconia Crown Prep Unacceptable
Although there are many benefits to using zirconia crowns, certain factors can disqualify a preparation from supporting a zirconia crown at all. In order to support a zirconia crown, the crown prep tooth must not have:
- Any undercuts or a gutter preparation
- A 90-degree shoulder
- Parallel wall preparation
- Either sharp incisal or occlusal edges
In addition to the above, bevels are not recommended for zirconia crown tooth prep. Similarly, only consider Feather Edge preparations in unique cases. Although they are not recommended, they can be acceptable for full-zirconia crowns. Be sure to consult with your dental lab before using a Feather Edge preparation to ensure that the restoration can properly fit.
Considerations for Finishing Zirconia Crowns
Once you fit zirconia crowns, there may be a slight amount of finishing required to ensure maximum comfort and esthetics. After placing the crown, you should remove excess cement to prevent excess plaque formation and use non-cutting finishing burs to finish gingival margins. Using these methods may cause the surface to be slightly rougher, but you can polish the zirconia to ensure a completely smooth surface.
If adjustments are necessary, be sure to use a fine diamond bur that is appropriate for a zirconia restoration and minimize the amount of pressure to prevent heat production. Using water during the adjustments may also help reduce the temperature.
Provide Patients with the Highest-Quality Zirconia Crowns
A careful crown prep procedure is a vital part of installing zirconia crowns, but just as important is the quality of the crown itself. When searching for the perfect zirconia crown for your patients, look no further than PRO-Craft Dental Laboratory. We offer multiple types of zirconia crowns to provide patients with full confidence in their smile, including ALL-Z Solid Zirconia crowns, ALL-Z Plus Translucent Solid Zirconia crowns, and PRO-Z Full Layered Zirconia crowns.
When you source your restorations from PRO-Craft Dental Laboratory, you receive realistic, custom-fit, comfortable crowns. Each crown is created using our proprietary polishing process and our custom library for natural tooth morphology, providing maximum function and esthetics. Contact us today to learn more about your options for Zirconia crowns—we don’t just make restorations, but we are experts in our craft, and we are here to support you in every step of the process.
