Technique to remove and repair a crown: thoughts?

Only cement in when angulation issues , otherwise always screw retained in my office

Usually cement with temp bond for all cement retained for this reason. Holds fine in 95% of cases. If you want to get creative, I imagine you could ask the lab to make a ledge in the crown near the cervical that could be large enough to fit the tip of a crown tapper. Could then fill in with composite like an access hole. If necessary drill out the composite and try the crown tapper.

I some cases, we have been able to drill a screw access hole to unscrew the abutment with crown still cemented. Then place composite when finished.

I too mostly use cement retained implant crowns. Back in the 1990's, the popular thing was screw retained, now it has come back in style due to, in my opinion only, poor post cementation protocols (aggressive cleaning with clinical and xray visualization). Air abraid the abutment making a protectant for the tissue flange and seal the screw hole with teflon tape about 80% full. Then use Premier Implant cement as the first round obviously with both thoroughly clean and dry. If a crown comes off, I will use standard bonded ceramic crown protocol, Monobond/Veneer Cement in my office. I make my own CEREC crowns so I am typically using GC CeraSmart or eMax if in the ethetic zone. I can easily convert my cementation to a screw retained system by prepping an access hole after cementation, but haven't had the reason to do it/retreave or I could buy the corresponding eMax screw retained implant blocks etc but adds cost and complication. I am sure I will eventually get back to 50/50 or so but only due to clinical needs, my first choice is always cementation. I recall my implant patients every 3 months as there is little scientific basis for every 6 months (more basis for q4 in healthy adults).

I've had a problem lately with more abutment fixing screws coming loose under cemented crowns--so much so that I'm tempted to change my torque wrench (how do you know if those things are accurate anyway?). I've used only a few screwed -in restorations, but because of this problem I'm thinking of switching.

Screw retained all zirkonium or emax are fantastic restorations !! Try em you'll love it

two questions posed previously. How to remove cemented crowns and why do screws come loose. Answers from my perspective: I screw retain the posteriors since screw angulation is usually through the occlusal surface. I cement most of my anteriors since I want the implant in maximum bone (maxilla flares facial) and not try to orient the implant so the screw comes out the cingulum. The apex of the implant will often times exit the labial concavity. Then I use tempbond to cement. If I need to get the crown off I either cut a small slot in the cingulum and use a dentcorp pneumatic crown remover to tap it off (best investment ever!). If that doesn't work I dry the crown real well, warm up a Richwil crown and bridge remover by Almore (basically a gummy bear) and embed the crown in the gummy bear. Chill it very well then use a hemostat to grab into the chilled mass and wiggle the crown off. I can usually get them off this way. Second, if you're having screws coming loose check the occlusal function on the restoration. However, most likely your lab is using aftermarket parts that do not have the precise fit as those of the original manufacturer. Many labs are making their own abutments in violation of the FDA. Abutment manufacturers need to have a 510(k) clearance to manufacture abutments. Most labs don't. Also, some after market abutments are not designed the same way as the original so, if you're using a conical connection type implant, the conical part of the abutment may not fit as precisely so more force goes to the screw and it loosens. I'm sure I'll get flak about this from some of the aftermarket companies but, as a prosthodontist, one of my jobs is removing screw fragments then I need to find out what abutment system was used so I can get the correct replacement screw (original manufacturers screws often don't fit aftermarket products). It is actually quite rare for a lab to use OEM (original equipment manufacturers) parts because they're more expensive than knock offs. So.... buyer beware when asking for abutments. If you're using the more precise conical connection implants then the abutment/implant interface is an integral part of the overall design of the implant and should be revered as an important part of the overall restoration. Don't short cut this critically important mating surface. Make sure you specifically ask for an original abutment or one of the after market companies that has true FDA approval. Hope this helps.

what cement are you using?

Hello I cement almost all crowns, with temp-bond if metal base, ketac-cem if zirconia If I have problem, rarely, I transform the cemented crown to screw retained crown by drilling a screw access : it's easy and can be done in 2 mn and then refill the hole with fluid composite in 30s

My go to cement is simply tempbond. It's soft, radioopaque, chalky white (easily visible) and easy to clean. A weaker cement for tall abutments is Temrex. A little stronger cement than tempbond is tempocem, and then I move to Flecks (zinc phosphate) for the strongest retention.

Consider taking a photo of the abutment access tube before cementing so that there's little doubt abut where to drill if the need arises ? Has proved useful in my case.

I developed a technique to solve this problem and published it in 2015 January issue of Implant News and Views...pages 5-8. If the publisher of this forum will contact me, I ill send him the article, and he can put it up on this site. It is entitled Bail-out procedure for Cement Retained Crowns on Implants. It is really a simple solution, will save the crown and avoid a lot of aggravation.

To see Dr. Rudick's technique, please download Implant News and Views (PDF file). It's on page 5-8, in the PDF. Thank.s

Thank you for sharing that technique Dr. Rudick. Good, on-the-fly, re-purposing of the Tofflemire band as well.