Removing Dental Cement Inside A Zirconia And Lithium Disilicate Crown

By: Lee Ann Brady, DMD
This Topic Originally Appeared on PankeyGram.Org. Dr. Brady granted permission for igniteDDS to share with our readers

Sometimes a crown comes off and if it’s not damaged and the tooth structure is healthy still without any caries lesion, we can recement the same dental crown to the patient without needing to fabricate a new one.

To increase the bonding strength of this dental crown and prevent it from falling again, the inside of the crown needs to be cleaned thoroughly without leaving any small part of the old dental cement in it. Depending on the type of restorative material the crown is made of, there are different techniques to remove the dental cement.

So, what is the best way to go about this? 

Distinguishing The Dental Crown Material

First, we need to know if it is a zirconia or lithium disilicate crown.

If you have a radiograph of that restoration, you can tell immediately which one of those two things it is. If you don’t, you can always attempt to X-ray it. (That’s what I do.) Alternatively, you can assume the dental crown is made of lithium disilicate, which is the more technique-sensitive material when it comes to removing cement. 

For crowns confirmed to be zirconia, employing 30-micron aluminum oxide air abrasion effectively clears out the old resin cement. Subsequently, re-etching the inside of the zirconia prepares it for reseating. For lithium disilicate crowns, this approach should be avoided to prevent crack propagation. 

Two Alternative Methods For Lithium Disilicate Crowns

The lithium disilicate material is more technique sensitive, therefore if you employ these two different methods you are less likely to cause any crack or damage to the dental crown. 

1. Evaporating The Dental Cement In A Porcelain Oven

The crown can be placed in a porcelain oven to liquefy and evaporate the old resin. However, caution must be exercised to avoid rapid heating of the hydrated ceramic that has been in the oral environment.

Rapid dehydration will introduce cracks and lead to crown fracturing. 

2. Utilizing A High-Speed Handpiece with a Brown Silicone Point

A brown silicone point in a high-speed handpiece, adjusted gradually to the lowest speed is can effectively remove resin without damaging ceramic. 

How will you know when all the resin has been removed? When etching lithium disilicate crowns, whether using red 5% hydrofluoric acid or Monobond Etch & Prime from Ivoclar Vivadent, any remaining resin will be evident because the dye sticks to it after the etching solution is rinsed off.  

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