Combination Crowns & Partials

This clinical case study is a Combination Crown & Partial case that spans teeth #6-11. When the patient came in, he had space between his front teeth and he had a tooth missing on tooth #10, which was visible when he smiled. We were able to replace a lot of lost function for him while satisfying our esthetic demands, too.

You'll notice that tooth #10 is broken off at the gumline. It will need to be removed.

The patient desired a bridge from tooth #9-11 and then crowns on tooth #6, #7 & #8 just to improve his smile.

As I examined his smile, however, I realized that all of his upper posterior teeth were gone. As I looked at his lower arch, his lower molars and one of his lower bicuspids were gone as well.

I suggested to the patient the idea of using partial dentures to replace his missing teeth. The patient decided, however, to move forward with the crown & bridge on those front teeth.

After we had prepared the patient's teeth, including impressions and temporizations, he returned to the office to tell us that he did in fact want to replace all those missing teeth.

We called the laboratory to inform them this was now going to be a combination case, and the casework was sent from the PFM department over to the Combination Crowns & Partials department. The Combination Crowns & Partials department has its own PFM team so they can ensure that all the PFMs have the same contours, guide planes and characteristics necessary to maintain a partial denture.

When the patient returned to the office, we removed the BioTemps provisionals. We had already let the laboratory know that this case was changing from a regular crown & bridge case to a fixed combo case using both fixed bridgework and partials.

For this case, the fixed bridgework and partials will rely on each other for support, strength and function. At this point, everything has been fabricated. We are going to try everything in: the bridge spanning teeth #9-11, the splited crowns om tooth #7-8, and the single-unit crown on tooth #6.

You can see that we have an ovate pontic receptor site on tooth #10. That tooth was extracted and a BioTemps was placed immediately into that socket to help preserve that spot.

As you can see, I have some tissue rebound; as I push up, the tissue blanches slightly. Thanks to the Two-Cord Impression Technique, I was able to prepare slightly subgingival margins without ever having to take a bur under the gum tissue.

When we place restorations and push them into place, I do so using an orangewood stick. The orangewood stick allows me to check the incisal plane.

The orangewood stick also allows me to check that tissue pushback to see how far these are going to actually seat. When I put these bridges in with cement, of course, that tissue is going to be negated and that blanching will go away in less than 20 to 30 minutes.

Here you can see, on tooth #6 & #11, the VKS attachments coming off the distal.

This is a very critical point in the case. We've tried the crowns in, and we're getting ready to do a pickup impression. We remove the crowns and temporarily cement them into the mouth. If you only learn five things in this case study, I hope this is one of them: You have to temporarily cement these crowns into place to ensure that you get a good pickup impression.

A big problem we see at the lab is poor pickup impressions. This happens all too often because dentists will set the restorations into place and then take an impression. When that happens, the restorations move on the teeth and then the laboratory ends up with an inaccurate pickup impression.

My assistant has taken polycarboxylate cement from Ultradent and mixed in some Vaseline to prevent it from becoming rock hard.

We are now temporarily cementing these units into the mouth.

It's a little bit of a hassle to clean up, but it's the only way. I've tried using Fit Checker. I've tried using extra light body impression material. Nothing else works.

Here my assistant paints adhesive on the perforated custom tray.

We are using impression material to go around the attachment. We use the intraoral tip to go around the VKS attachments.

We going around the gingival margins of the PFM as well, making sure we capture these details for the laboratory techniciaN. We will go along all the lingual margins as well.

We use the same monophase material in the tray as well. It is very thixotropic, so it won't push tissue out of the way when we are taking a full-arch impression for a removable.

You can see the temporary cement inside the crowns in the pickup impression. It's very important that you DO NOT cement these crowns into place. This is another thing I'd like for you to take away from this case study: Do not cement the crowns just because they are in your hands and it seems like the natural thing to do.

Regarding impressions: First, triple trays should never be used for a combo case or bridge. Second: Provide a full arch impression along with the quadrant if the case is 4 units or more. Finally, the lab won't fabricate crowns with attachments on a quadrant impression. We need to establish a path of insertion and parallel cross arch.

Looking at our design sheet, we see that we need to make some clinically prepared rests here, on the two lower bicuspids on the lower right. On the lower left, we need to make a clinically prepared rest in the mesial pit of the bicuspid and one on the distal lingual of the cuspid. Here I use a round bur, like I was taught in dental school.

The lab pointed out to me that when I used the round bur, they took a look at it, they had a hard time seeing the draw/the path of insertion.

There are undercuts here from the round bur. It kind of makes sense. If you insert a round bur to make an inlay-type preparation into the tooth, which is what we are doing here with a rest prep, and you go beyond the height of contour, you will end up with an undercut.

Undercuts are bad news. After the lab called and told me this, I switched to the correct bur: an 845 KR-018 bur. It's basically a small inlay bur that you would use for a bicuspid inlay. The taper of the bur will ensure that we don't undercut any of the walls. With a modified shoulder on the internal line angle, it is also going to make sure that is nice and smooth.

You can see the difference in the look of these rest preps. These preps should be deep enough that the rest is going to fit into there, and also thick enough so that the metal doesn't have any problems.

We don't want to adjust the opposing teeth just because we have an occlusal rest there.

Once the lab instructed me on how to make these cuts with the correct bur (using the inlay bur rather than the round bur), we did that. We once again take our final impression using the monophase material. It picks up a lot of small details, and when we put it into the tray it won't push the tissue around as opposed to a heavy body vinylpolysiloxane material.

As we look at the final impression, the residual ridges on both sides look nice. You can see what a good job it does, not only recording the teeth in the anterior and the rest preps, but recording the soft tissue anatomic landmark. Monophase material really does a nice job of that, making it my choice material for this type of impression.

NEXT APPOINTMENT: We have removed the BioTemps provisionals and we have the finished framework as well. The bridge is engaged onto the VKS attachments, which you are seeing me try in.

You can try the crowns on first. What I try to do now is find the relationship between all of this stuff to ensure it fits. I like to put the crowns in the attachments in first. For me, it's easier than trying to push the partial down and engage those VKS attachments into the female.

Let's take a closer look at the upper partial denture. It's a very esthetic partial denture. As you look at it, you'll notice it's claspless.

You can see our two VKS attachments to the distal of the two cuspids. You can also see how much vertical space we need for the VKS attachements, or the "trailer hitches," as my patient called it. You need at least 5 mm, preferably 6 mm, of room between opposing arches to have room for an attachment like a VKS attachment.

There was no need for crowns on the lower. As a result, we went with a more conventional partial and did not use attachments of any kind.

Of course, on the lower, because of the way patient's smile, the lips tend to cover these up. We have an akers clasp on one side and a roach clasp on the other. It's not as big of a deal on the lower. When the patient smiles, you tend to see the incisal half of their lower front teeth, but not much more of the partial beyond that.

We are now ready to cement the units. Before we cement the, we clean the teeth with Consepsis® (Ultradent). You have to assume that your temporaries leaked a little bit or that saliva has gotten on the teeth today after the temporaries came off.

Now that we have disinfected the preparations, it's just a matter of keeping them somewhat dry (unlike the old days where we had to air dry the preparations and get them bone dry). Today, we just try to avoid pools of moisture. I use a cotton roll to check that everything is nice and dry. Resin-based ionomer cements, however, don't require bone-dry preps.

You'll notice I've got the bridge on one side and the crowns on the other side, and both are already engaged in the VKS attachments. I've had difficulty with this in the past, so when I put them in here at the same time, I want to make sure that the attachment is engaged when it goes in.

You will always see me put the partial and the restorations in at the same time. I do this because it ensures that I have a proper relationship between the two.

The partials are still place, even as we clean up the excess cement. This is RelyX™ Luting Cement Plus from 3M ESPE. It provides you with a very easy cleanup. We clean up all the facial areas – anything we can get to with the partial still in place.

We will give the cement plenty of time to cure on the 3-unit bridge spanning teeth #9-11 and the single-unit crown on tooth #6. Once we have given that cement enough time to set, we pop out the upper partial, which disengages the attachments. Clean around the lingual and interproximal, then put the partial back in.

We then delivered the conventional lower partial that required only clinical rest preps (no restorations). As I take out the lower partial, I see one spot that appears to be high.

I ask the patient to bite without the lower partial in place, which confirms that there is a spot on the lower partial holding the bite open. I adjust that and put it back in.

The after portraits say it all. Look how nice he looks. Before, when he smiled, he had space between his front teeth and missing tooth on tooth #10.

We may have to teach this patient how to smile again! You can see he has a nice broad arch, and the shade he picked looks really nice in the mouth.

This patient will never regret the decision to replace his posterior teeth. We were able to restore lost function and still achieve esthetics that pleased both of us.