Polishing a Posterior Zirconia Restoration

Using the right tools can avoid abrasion of the opposing natural tooth

Lee Culp, CDT

Figure 1 | All-ceramic full-contour monolithic restorations fabricated from zirconia have become a popular replacement to traditional metal ceramic restorations in the posterior region because of the growth of digital CAD/CAM design and manufacturing, the inherent strength of monolithic zirconia, and the esthetics that can now be achieved with more translucent zirconia offerings. With the success of the new application of this material, there are many misconceptions and misunderstandings concerning proper use, preparation, cementation, and, more importantly, how to properly facilitate intraoral adjustments and polishing after possible occlusal adjustments.

Advantages of the monolithic all-ceramic zirconia crown include minimal possibility of fracture or chipping and high strength. However, zirconia full-coverage crowns have the disadvantage of possible abrasion of the opposing natural tooth if proper polishing techniques and instruments are not used.

Conventionally, greater hardness has been believed to cause more wear. According to scientific studies, however, there is no significant correlation between the restoration hardness and the degree of wear of antagonistic teeth. The degree of wear is more affected by the surface structure and the roughness of the restorations after adjustments. Less wear of antagonistic teeth was shown with zirconia than with previous feldspathic dental porcelain. As for the treatment of the zirconia surface, the degree of wear of the antagonistic teeth has been found to be less in the polished zirconia groups than in the zirconia groups with glazing or surface adjustment. A properly polished zirconia full-coverage crown shows reduced antagonistic tooth wear.^1,2

For dentists and technicians to efficiently and predictably polish the lingual surface of an anterior tooth or the occlusal anatomy of a posterior restoration, Brasseler USA has introduced a new addition to the Dialite® family of porcelain polishers, the Feather Lite™. Feather Lite’s flexible spirals are designed to separate and feather out. This feathering helps to maintain surface differentiation when polishing porcelain restorations, allowing the instrument to quickly adapt to any surface.

References

1. Jung YS, Lee JW, Choi YJ, et al. A study on the in-vitro wear of the natural tooth structure by opposing zirconia or dental porcelain. J Adv Prosthodont. 2010;2(3): 111-115.

2. Janyavula S, Lawson N, Cakir D, et al. The wear of polished and glazed zirconia against enamel. J Prosthet Dent. 2013;109(1):22-29.

About the Author

Lee Culp, CDT, is the CEO of Sculpture Studios in Morrisville, North Carolina. He is also an adjunct professor at the University of North Carolina School of Dentistry.

For more information, contact:
Brasseler USA
800-841-4522
www.brasselerusa.com