Preparation Guidelines for Full Zirconia Crowns
Zirconia restorations, since its debut in the dental industry, have become the better choice for dentists who aim to provide their patients with the most technologically-advanced metal-free dental restorations. It has proven to be a great improvement since there is a wider array of available milling pucks that allow for greater shade translucencies and variation that closely resemble natural teeth. In addition to improved esthetics, the physical properties of Zirconia also allow for strength, durability, and precision-fitting restorations.
If dental professionals want to maximise the success of Zirconia restorations as well as to have minimal chair time, it is of utmost importance that the proper preparation and guidelines are followed. Know more about the different preparations here:
PREPARATION GUIDELINES FOR ANTERIOR ZIRCONIA CROWNS
When the dentist is preparing a tooth for an interior Zirconia crown, there should be enough room for the wall thickness – there should be a required minimum of 0.3mm and at least 1.0mm and 1.5mm, or 1.8 to 2.0mm incisal reduction. There should also be a visible and continuous circumferential chamfer with at least 0.5mm reduction at the gingival margin. It is also important for the vertical and horizontal preparation of the tooth should have an angle of approximately 5 degrees and a bevel is certainly not advisable. All incisal edges should also be rounded.
PREPARATION GUIDELINES FOR POSTERIOR ZIRCONIA CROWNS
When preparing a tooth for posterior Zirconia crowns, on the other hand, you need to make sure that there is enough room for the wall thickness to have a minimum of 0.5mm and at least between 1mm and 1.5mm or 1.5 to 2mm occlusal reduction. The preparation should be tapered between an angle of 4 and 8 degrees. There is also a need for visible and continuous circumferential chamfer and reduction-wise, there should be at least 0.5mm at the gingival margin. Similar to that of anterior crown preparation, a bevel is should also not be used. All occlusal edges should be rounded.
Factors That Make Crown Preparations Unacceptable for Zirconia Restorations
In order for a crown prep to be acceptable for a Zirconia crown restoration, the prep should not have any undercuts nor a gutter preparation. A 90-degree shoulder is also unacceptable as well as parallel wall preparations. Occlusal edges or sharp incisal are also not suitable for Zirconia restorations.
Cementing and Finishing a Zirconia Restoration
Oftentimes, marginal finishing is required when fitting and cementing a Zirconia restoration. Excess cement, if there’s any, must be removed to avoid plaque formation that can lead to tooth sensitivity and periodontal disease. Although there are some adjustments that might slightly roughen the surface of Zirconia restorations, it should still be easy to polish to create an exceptionally smooth surface.
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