Full Contour Monolithic Zirconia Crowns
The development of full-contour monolithic zirconia crowns promises an end to the heartbreak of fractured esthetic porcelain on posterior crowns and bridges.
Monolithic zirconia crowns can be prepared just like conventional PFM crowns using a butt shoulder, a chamfer, or a knife-edge finish line. Monolithic zirconia crowns may be fabricated with as little as 0.5-mm of occlusal reduction, and most importantly, monolithic zirconia crowns can be cemented using the clinician’s choice of favorite conventional cement. The only difference between a monolithic zirconia crowns and a conventional PFM crown can be summed up in one word—unbreakable.
The monolithic zirconia crowns and bridges are early restorations were often rather boxy-looking and although the color was close to the desired shade, the final restoration was usually too high in value. However, the shapes and contours of the new monolithic zirconia crowns are easily altered using a low-speed green stone. The monolithic zirconia crowns is very easy to shape and it is equally easy to polish using conventional low-speed porcelain-polishing materials.6 It only takes a few minutes to correct the occlusion and any contour issues and achieve a very smooth finish for the final restoration. Because monolithic zirconia crowns are the same color all the way through, they will not exhibit the opaque show-through so often seen when adjusting the occlusal portion of a PFM crown.
Although the wear factor against opposing natural-tooth enamel, the smoothness of the surface of the monolithic zirconia restoration—along with point-fossa contact with the opposing arch—has not caused any noticeable wear on the opposing natural dentition.
Controlled studies of monolithic zirconia crowns have shown wear against opposing natural-tooth structure to be only slightly less abrasive than natural tooth enamel. When comparing highly polished and glazed monolithic zirconia crowns and IPS® e.max crowns (Ivoclar Vivadent, www.ivoclarvivadent.com), studies have documented that monolithic zirconia crowns are just slightly less abrasive against natural tooth enamel. When compared to other less robust full-coverage options, the monolithic zirconia crown is unbreakable and less abrasive to natural enamel than any other full-coverage ceramic system.