In recent years, the status of zirconia blocks in the field of dentistry has been irreplaceable and indispensable. For the lab side, zirconia blocks replace titanium, which is a great improvement in both aesthetics and practicality; for the patient, it saves them time and money and is more aesthetically pleasing and safer. Therefore, we need to pay attention to some small problems in the production of zirconia crowns.
Instructions For Preparing Anterior Zirconia Crown
When preparing teeth for anterior zirconia crowns, you need to ensure that there is enough room for a wall thickness of at least 0.3 mm, ideally 1.0 to 1.5 mm, or 1.8 to 2.0 mm for an incisal reduction. The gingival margin should have a clearly visible and continuous circumferential chamfer, reduced by at least 0.5 mm. The horizontal and vertical preparations of the teeth should have an angle of approximately 5°, bevels are not recommended. All incisal edges should be rounded and you want to reduce the tongue of the front teeth with football diamonds to create a concave tongue.
Instructions For Preparing Posterior Zirconia Crown
When preparing teeth for posterior zirconia crowns, you need to ensure that there is enough room for a wall thickness of at least 0.5mm, ideally a 1mm to 1.5mm or 1.5 to 2mm occlusal reduction. The preparation should taper between 4° and 8°. It also needs to have a clearly visible and continuous circumferential chamfer and needs to be reduced by at least 0.5mm at the gingival margin. Just like preparing anterior crowns, bevels are not recommended. Make sure all bite edges should be rounded. While shoulder and chamfer preparations are ideal, feathered edge preparations are generally not recommended but acceptable for full zirconia crowns. Check with your dental laboratory to see if their manufacturing process allows this form of preparation, as different types of zirconia require different guidelines.
Factors That May Make Crown Preparation Unacceptable For Zirconia Restorations
For a zirconia crown restoration to be acceptable, the preparation should not have any undercuts and should not have groove preparations. Neither 90° shoulder nor parallel wall preparations are acceptable. Sharp incisal or occlusal edges are not suitable for zirconia restorations.
Cementing and Finishing a Zirconia Restoration
Often, edge trimming is required when installing and bonding zirconia restorations. Excess cement, if any, must be removed to avoid the formation of plaque that can lead to tooth sensitivity and periodontal disease. Although some adjustments may make the surface of the zirconia restoration slightly rough, it should still be easy to polish to create an exceptionally smooth surface.
