By Lee Ann Brady, DMD 

When a crown comes off and we are going to put it back in the mouth, we need to remove the old resin cement that is inside the crown. What is the best way to go about this? 

First, we need to know if the crown is made of zirconia or lithium disilicate. 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 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 crowns presumed to be lithium disilicate, this approach should be avoided to prevent crack propagation. 

In the case of lithium disilicate crowns, two alternative methods can be employed: 

1. 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. 

1. An alternative method involves using a brown silicone point in a high-speed handpiece, adjusted to lowest speed. A brown silicone point at slow speed effectively removes resin without damaging ceramic. 

How will you know when all the resin has been removed? When etching lithium disilicate, 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.  

By Lee Ann Brady, DMD 

For addressing the access hole of a screw-retained implant crown, my preferred method involves applying Teflon tape over the hole followed by temporary filling material, such as Telio Inlay from Ivoclar Vivadent. 

I emphasize to patients the importance of maintaining accessibility to the screw for potential adjustments without jeopardizing the integrity of the ceramic crown. Hence, immediately after seating the crown, I ensure no adjustments are needed before doing the filling. 

Patients are scheduled for a final post-op appointment with the surgeon after the restoration is in place. If there are no issues requiring crown removal, the Teflon tape and Telio Inlay may remain indefinitely, monitored during hygiene recall appointments. As long as the temporary filling remains intact, replacement is unnecessary. 

In cases where the Telio Inlay dislodges but the Teflon tape remains intact, I inform the patient of our plan to reapply the temporary filling. However, if repeated dislodgment occurs, leading to inconvenience, we consider transitioning to a permanent filling. In such instances, fresh Teflon tape is applied, and the access hole is filled with composite that precisely matches the crown’s color. 

Even if years pass and the Telio Inlay needs replacement, I opt for a temporary filling for ease of identification if removal is necessary. Only if frequent filling replacements prove bothersome do I consider switching to a permanent filling because I prioritize easy retrievability of the screw. 

Most of us are placing implant crowns, using screw retained crowns. If the crown needs to be recovered, or the screw needs to be changed or tightened, the restoration can be removed by accessing the screw through the screw channel.

One of the main advantages of screw-retained crowns is the ease of retrieval. I have discovered two ways to make retrieval easier for myself, which involve the colors of the Teflon tape and composite I use.

1. Now I have colored Teflon tape on hand, and when I place the screw, I put colored tape on top of the screw instead white tape. If I need to remove the composite, I more readily see my gray or yellow tape than I would white tape.
2. I also like to use a composite color that is not be an exact match with the implant crown. This way I can easily see the material to be removed to access the screw channel… if I need to remove the crown.

If you plan ahead to have colored Teflon tape on hand, you can do what I do. Teflon tape is available in multiple colors at Home Depot and other hardware stores.