Removing Cemented Crown: What is the Best Protocol?

Dr. Q asks:
I placed an immediate dental implant after extracting a broken down maxillary first premolar, along with an osteotome sinus lift. The implant system I used was Osstem, which is a Korean system. The implant body was 4.1mm and the neck was 4.8 mm. The implant had a polished collar. The grafted bone I used was DFDBA marketed by the name of SureOss, by HansBiomed, another Korean brand. The implant at the time of placement had excellent primary stability. I did primary closure of the soft tissue over the implant and graft.

I went in for the second stage about four months later, took a fixture level impression and restored the implant with a PFM, cemented crown on an angled abutment. Unfortunately the porcelain fractured off the buccal face of the crown after a few days. I tapped off the crown and had to use a fair amount of force because the crown fit so snugly, even with the temporary cement. I replaced the crown and cemented it shortly after.

Three months later the patient complained the crown was moving. I examined the crown and implant and found out the implant had failed. Could I have caused this by tapping too hard to remove the original crown? Is there a better way to remove cemented crowns? Could I have disrupted the osseointegration? How long should I wait to attempt another implant placement?

9 Comments on Removing Cemented Crown: What is the Best Protocol?

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Dr. C

9/6/2010

Buy a pnuematic crown remover. This is an essential tool if you are going to restore implants. It will usually "pop" most crowns off on the first try, assuming you have used temp-bond. I have taken off a few implants crown with no post-removal problems. If your patient is fracturing porcelain, occlusion may have been a problem from the start.

Carlos Boudet, DDS

9/6/2010

Dr. Q When I have to remove a crown and do not want to risk damaging anything, whether it is a post, a core buildup, an abutment or the implant, I always cut a slot in the crown to distort the metal and break the cement bond atraumatically. The cases where I broke something and got in trouble were those that I tried to tap the crown off. In my opinion, it is better to pay for a new crown and be safe. Good luck.

Dr. Samir Nayyar

9/8/2010

Well you should have cut the crown in 2 pieces with a bur & then make another crown as it is safe although its a bit tedious but it saves lot of your work as you have to do now. You Should wait for atleast 8 months.

Peter Wat

9/8/2010

Dr.Q I always take clinical photos of my implant cases, that way I knew where the position and angulation of the access hole in the abutment of the cemented crown. If I needed to remove the crown I simply drill a hole thro. the occlusal surface of the crown and I can undo the abutment screw. Its just like removing a screw retained crown. You can use whatever means to detach the crown from the abutment out of the mouth. Honestly speaking I think the implant may not have been fully integrated because simply tapping the temporary cemented crown off should not have been the cause for the implant failure. Dr. Peter Wat

Dr. Andrew H.F.Tsang

9/11/2010

Hi Dr. Q, I agree with Dr. Wat. An easy way for a stuck crown is to use a round bur to drill where the screw hole is. Then loosen the screwed in abutment. It's easier to separate the abutment for reuse out of the mouth. It could be likely that the implant failed later due to uncovered or uncovering threads of the implant. This could be resorption of the buccal plate of bone if it was originally very thin, or traumatized. Another reason could be due to pre existing pathology of the premolar extracted- Wait 3 months and you likely can do the entire procedure just by osteotomes. Take a CT to ensure your original angle was in the triangle of bone. Good luck!

smaragda tsigani

9/12/2010

hi there. i think that the implant faild maybe because of occlusal trauma or because you grafted an extraction socket in immediate placement of the implant.only if i have an extra root to cover i place graft, or else i leave space in the socket to be filled allone

Simple Doc

9/12/2010

What about using an ultrasonic scaler to vibrate the crown and break up the cement layer. I have heard of this being done but do not know exactly how this is done or if this poses a danger to the implant. Simple Doc

Dr shalash

9/21/2010

Just a few thoughts on your case: did u torque the implant before u attempted the second stage procedures. 4 months of loading or even tapping the crown should not cause a failure of your implant if it has been properly osseointegrated. i believe u may have rushed into restoring this implant considering that this was an immediate case with a closed sinus lift. I believe that the minimum u should have waited is six months. crowns that are used to restore implants should have a passive fit. having a tight crown (snug fit) like u have mentioned means that your implant is under a constant torque which would lead to eventual bone loss and failure of the implant. u can remove the crown by drilling an access hole through the top, and then unscrew the abutment with the crown on top. u should remove the failed implant, apply a new graft in the socket, wait for six months and then place a new implant. good luck

Monir taheri

12/24/2010

It has been very difficult for me to remove cemented crowns without damaging them . I wanna recement them later and these answers couldn`t persuade me. please show me a way to do this procedure successfully. Best regards and thanks a lot

Removing Cemented Crown: What is the Best Protocol?

9 Comments on Removing Cemented Crown: What is the Best Protocol?

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