IMPLANTS TOO CLOSE TOGETHER
IMPLANTS TOO CLOSE TOGETHER
Restoring implants with CEREC technology is now quite common and just about everyone in the cerecdoctors.com community is quite adept at handling the parameters. I've been placing implants for 5 years and restoring them for much longer. Other than the occasional odd case with aesthetic difficulties, I've never been stumped with anything bizarre--until recently.
I recently placed two implants on my assistant, Nadine, for sites #2 and #31 (see pictures #1 and #2). The upper was placed first, while the lower site was healing after I asked my oral surgeon to build up the ridge. I then placed the lower implant just like the upper, scanning first in CEREC, designing a final crown into proper alignment and occlusion, integrating into the SIDEXIS 4 software, and making CEREC Guides 2's. The implants were placed with ease.
Pictures #1 & 2
After appropriate healing, I placed scan posts/scan bodies on both implants to restore them. I designed the respective crowns and got bizarre proposals, because the implants were too close together in centric occlusion. Just to verify, I placed tibases on each implant, and sure enough my patient was unable to close her mouth all the way. Realizing that I needed to study this on models, I took PVS impressions and poured models. I placed the tibases onto the analogs, and sure enough, I was screwed (see picture #3). What to do?
After much head scratching, I realized I could figure this out. The restorations were going to be screw-retained anyway, so what's wrong with having the tibases occlude with each other (protruding right out the occlusal access holes) after I reduce them? Well, before doing this, I realized that I would have to reduce them too much. There would be very little left to lute to the crowns.
So then I thought, how about using stock abutments? Although I would still have to reduce them a lot occlusally, I would have wider abutments to gain some ferrule with the crowns. Brilliant! I had a Guinness to celebrate (see picture #4). However, they were still too short. But then I noticed that the two stock abutments had 2 mm tall aprons apical to their margins. Aha! A quick call to Implant Direct to order two more abutments with only 1 mm tall aprons solved the problem (picture #5).
Pictures #4 & 5
Now I had decent looking abutments to scan directly in CEREC. I knew the crowns would be short and would require lots of manipulation to get them to look decent, but it worked. I milled the crowns and had to carve out some residual ceramic in the centers for screw access to get things to fit together. I made sure to preserve the flat planes in the crowns that fit against the corresponding flat planes on the abutments. I adjusted occlusion in the blue phase on the models. Picture #6 shows the crowns at this stage. Pictures #7 and 8 show the restorations in the mouth after I luted with Ivoclar Multilink Hybrid Abutment Material. All that remained was sealing the access holes just like we do for all other restorations. In this case some metal is exposed.
Picture #9 shows a bitewing of the final restorations. They've been in the mouth for just two weeks. I was still able to get some teflon tape into the small spaces above the screws. The final two pictures shows the final restorations in the mouth.
Could I have avoided this problem? Yes. Before placing the second implant (#31), careful analysis of my inter-occlusal distance would have alerted me to trouble. My oral surgeon did too good of a job building up the lower ridge. You can see that my lower implant is rather small and short. I could have reduced the bone, placing a longer and deeper implant. Just 2 more mm would have avoided the problem.
I almost went for help to c-docs for this, but I knew I could figure it out on my own. Another problem solved with our great technology with CEREC.
Chris, it was just dumb luck that it was my assistant. There's no reason why it couldn't have been any other patient and I could have been left shrugging my shoulders. You know, I could have always said what the oral surgeons say: "Well, they're integrated, aren't they?"
the problem came from depth on placement of the first implant, you can see in the bitewing, unless that is distortion that it could have been 2 to 3 mm deeper giving you the running room for a better custom abutment that could also support the ceramic better, the custom abutment would give you more axial wall as well as you could drop the margin deeper and cement outside the mouth. i dont much care for second molar implants with the clearance you had to start with, but sometimes you dont get to deal the cards the way you like em ... tough case
Marc, you're absolutely right. First implant should have been deeper. Plenty of bone there. However, I was able to cement outside of the mouth, as I turned these into screw-retained restorations.
Eric, that is a tough case. When you did your digital work up did you put a digital abutment on it. I had cases similar to this and was able to catch the inter-occlusal space issue by placing more or less a custom abutment on the digital work up. You can create collar heights and emergence to see what is may look like. It has forced me to place implants deeper then originally planned. Here is a quick screen shot(not one I had space issues with). I have a 1mm collar, 4mm abutment with 3mm of room for restorative. These become incredibly valuable if you are have a specialist place the implant. Then they know that they may need to drop bone to give you room if needed. Nice work around on the case. Those are not fun.
Great post above by michael. The preop planning stages should have shown the need for the implants to be placed deeper. Have you gone back and looked at your plan to identify how this could have been recognized prior to surgery? I think that is the most valuable take home message from this case. The other way to restore a case like this is to use a ucla and make the restorations one piece all metal screw retained crowns.
Michael and David, thank you for your responses to this. I did not know anything about a digital abutment, but what a great thing. I should have measured inter-occlusal distance prior to placing implants, knowing tissue heights as well. This also shows how important this can can for any single implant, where the opposing tooth has drifted.
As someone else pointed out, the implants are placed too shallow. I am not sure what is on the mesial of the implant on 2. If I have to restore a case like this, I would probably do cast gold or titanium screw retained restoration. I don't think this will last too long. I can understand not wanting a big lab bill when working on the staff though.
You might also want to replace her crowns on 3 to 5.
Not every case goes perfectly despite our best efforts and planning. What separates the men from the boys is how we handle these less than perfect situations. Kudos for making lemonade from lemons. Nice work around.