Zirconia crowns have become a widely used option in modern dentistry, valued for their exceptional strength and natural appearance. A crown functions as a cap placed over a damaged tooth, restoring its shape, size, and function. The material, a form of zirconium dioxide ceramic, is known for its durability, which allows for thinner crown walls compared to other materials. While the goal of the manufacturing process is a perfect fit, minor adjustments are often required after placement. The answer is yes, zirconia crowns can be reshaped and adjusted, but this process requires specific tools and a careful finishing protocol to maintain the restoration’s integrity.
Reasons Zirconia Crowns Need Adjustment
Even with advanced digital scanning and milling technology, minor adjustments to a zirconia crown are sometimes necessary after placement. The most common reason for modification is an issue with the patient’s bite, known as occlusal interference. This occurs when the crown feels “high” or makes contact with the opposing teeth prematurely during chewing.
These small imperfections can cause discomfort, and if left uncorrected, they may lead to jaw pain or excessive wear on other teeth. Dentists also adjust the crown’s margins to ensure a seamless seal with the underlying tooth structure. Aesthetic contouring is another element, ensuring the crown blends well with surrounding natural teeth.
The Process of Adjusting Zirconia Material
Reshaping zirconia is a demanding process because of the material’s extreme hardness, which is greater than many metals used in dentistry. Specialized tools are required to remove the material effectively and safely. The procedure typically involves a high-speed dental handpiece equipped with fine-grit diamond burs specifically designed for ceramics. Using a fine-grit bur allows the clinician to remove material with precision while minimizing the creation of deep scratches or micro-fractures on the surface.
A constant stream of water coolant is necessary throughout the grinding process to prevent heat buildup. This water spray prevents heat from damaging the crown or the underlying tooth, which could potentially cause a structural change in the zirconia itself. The dentist must employ a light, intermittent touch, as excessive force or heat compromises the crown’s surface integrity and leads to structural weakening. Only the necessary amount of material is removed to correct the fit or contour, preserving the crown’s overall strength and longevity.
Protecting the Crown Surface After Reshaping
The step following material removal is crucial for the crown’s long-term success and the health of the patient’s mouth. Any grinding, even with specialized fine burs, creates microscopic roughness on the zirconia surface. This roughened texture significantly increases the rate of wear on opposing natural teeth and promotes the accumulation of dental plaque. A smooth surface is biologically necessary because bacteria adhere much less readily to a polished material.
Therefore, after any adjustment, the surface must be restored to a high-luster, mirror-like finish. This is achieved through a meticulous process of mechanical polishing, which is often preferred over re-glazing for occlusal surfaces. The polishing procedure involves a sequence of specialized polishing instruments, such as rubber wheels, cups, and points, impregnated with diamond particles.
Polishing Steps
The process requires sequential steps:
- Begin with a medium-grit polisher to smooth the scratches left by the initial grinding bur.
- Follow with progressively finer grits to eliminate microscopic imperfections and achieve a satin finish.
- Use a very fine diamond polishing paste applied with a soft felt or goat’s hair wheel to generate the required high shine.
This careful restoration ensures the crown is gentle on the opposing teeth and maintains resistance to plaque and staining. A properly polished surface is essential for patient comfort and oral hygiene.