Technical advisor Tony Megale shows you how to make occlusal adjustments on a full-contoured zirconia crown. Tony takes you through the steps and tools used to achieve the required high luster.
If it looks like only minor adjustments need to be made you could consider adjusting the opposing dentition before altering the zirconia. You will also want to ensure that the patient does not close down heavily on the crown while you are checking the occlusion and contacts. You only want very light contact with the occlusion until the crown has been cemented. It is very important to restore the zirconia to a very highly polished luster.
If you do need to make adjustments to the zirconia crown, it's important to know that once the surface of zirconia has been roughened, it will not become smooth again over time. Rough zirconia will cause excessive wear on the opposing teeth so it must be avoided.
Highly polished zirconia, however, has minimal wear on the opposing tooth structure. This is why it's important that once you have altered any of the polished surface of the zirconia crown that you make sure that all of the rough areas are mechanically smoothed utilizing rubber wheels and points. You must then finish with a polishing paste to achieve high luster. The occlusal surface of any zirconia restoration should never be glazed.
There are several great polishing systems available such as Dialight ZR, Ceramo-Dots, and Zircon Bright. All of these polishing systems can be used chairside for polishing roughened zirconia as well as E-max, PFM's and composite restorations.
-When reducing high points on the zirconia crown use a Dialight ZR rubber wheel or a football shaped finishing diamond to make these adjustments.
-Once the occlusion has been adjusted use a medium polishing wheel or a medium polishing point to shine and remove all roughness from the surface of the zirconia.
-Next utilize a fine polishing wheel or a fine polishing point to high shine the entire occlusal surface making sure there is no rough areas remaining.
-The last step is to use a Cermo-Dotz brush or Zircon Brite paste to bring the zirconia surface to a high luster. Then clean and cement
-Something to be cautious of is that excessive pressure with a handpiece or heat generation can cause a phase shift or introduction of flaws which can lead to propagation of cracks and even failure of the crown during this process.