Managing caries in primary molars: Using crowns

OK. So what about if we have a much bigger hole or we have a small hole but an uncooperative child? What can we do in these situations? Well we know that a conventional restoration is less likely to work, because the bigger the hole the more we’re asking from the filler material the more likely it is to fracture. We’re also particularly composites have more risk of leakage when we have large restorations as well. So what do we use in these scenarios? Well, probably what we use is some sort of crown. And what we do have is a Cochrane review that looks at preformed crowns of all types the decayed primary molar teeth.

And what they said was that they are likely to reduce the risk of major failure in the long term compared to fillings. So we know that some sort of crown is the way to go. So what kind of crown? And we’ve got three options here. We’ve got a preformed metal crown with preparation, a preformed metal crown with no preparation, then we have a zirconia or a white crown, yeah. Which has significant preparation. OK. And so again if you look at the Cochrane review, can that tell us which is best? Unfortunately, it can’t. What they found was with regards to crown type they couldn’t really give any recommendations as to which we should use. OK.

So if Cochrane can’t help us, we need to start making our own decisions. And so what we need to do is start looking at individual RCTs ourselves to work out which of these we might like the look of. All right. So there are three types like I say, preformed metal crown with preparation, preformed metal crown with no preparation, and white EG zirconia type crown with significant preparation. OK. So the first we can get rid of is the white crown. The evidence for white crowns is on the whole poor. And when you look at the papers in detail it’s quite easy to pick out. On top of that, white crowns are technically more challenging to do.

They’re certainly more challenging to the patient and often necessitate the pulpotomy or pulpectomy or some other kind of pulp treatment as well. So white crowns, we certainly, this institution, myself, we cannot recommend them because the evidence base is not great and they’re more trying for the patient. OK. The next to go is preformed meta; crown with preparation. Again, if we’ve going to purely look at RCTs, the evidence really isn’t there. Yeah. And what we’re left with is preformed metal crowns with no preparation or whole crowns. And whole crowns now there are two or three really quite good RCTs supporting them. So in the context of this talk what we recommend we think whole crowns are the way to go.

So developed in Dundee and essentially you just push the crown on to the tooth. No caries removal, no preparation, though you might use separators to make some space mesial distally. No local. No rubber dam. So really, really simple for the dentist to do, also really simple for the patient to experience as well. OK so what are the implications for the whole crown? As I’ve already said, no irreversible pulpitis, you have to have a healthy pulp. And for that you probably need pre-op X-ray, all right, to be sure nothing’s going on. It’s great for caries, it’s particularly good for children who might have anomalies affecting Es or Ds. And it’s great for children who can’t cooperate.

So for example, we regularly avoid GA in three-year-olds, four-year-olds, because we use whole crowns to manage the disease in their primary molars. So we’re going to run through the technique now. Each slide’s going to have a speech bubble like you can see on this slide. And the speech bubble I put some tips that our students have given us. So maybe you can use these in your own practise to help you put all whole crowns on in the most effective way possible. OK, the starting point is really to make sure everyone knows what’s going to happen. It’s really important you describe the crown.

Make sure the family knows how it’s going to look, and the child knows how to go how it’s going to look. Explain the steps really carefully how are you going to get from start to the crown being placed so that the child knows what to expect. You might even put some topical on the child’s tongue so they can feel the taste, because you might use topical as crown placement. Warn about the fact that the bite will be off, they will be occlusal derangements for about a day afterwards. And warn the crown will feel tight right away.

So a lot of students and a lot of people who come to talks we give are worried that families will accept metal crown, I think part of it is how you sell it. And what we use, you can see in the speech bubble, we use phrases like, it’s a pirate crown, or it’s an iron-man tooth and often children really buy into that. OK. So you tell them how you’re going to do, the next to decide what you’re going to do. We’ll touch this more in the treatment planning talk. But remember in terms of teeth to save, these are really important teeth because they hold the sixes in place. These are a little bit less important.

So if you’ve only got a set amount of co-operation, use that for the Es. Don’t waste it on the Ds. OK. Think about which teeth you’re placing and on which visit. So if you have to say, put crowns on all four E’s, if you put a crown up here and down here in the same visit, that’s twice the amount of bite propping open you’re going to get, and you want to avoid that. So if you can, perhaps do two upper ones or two lower ones or you can diagonal. OK, in that way you minimise the occlusal derangement. Make space for the crown. OK, there may be space already, in which case just let it on.

If there isn’t space, we often recommend using separators. And our students sometimes use rubber dam forceps to make the separator wider. Or sometimes use floss and let the child pull the floss out to involve them in a separator placement. We tend to leave separators in for a week, because that’s how our appointments work. But some of our students, again, leaving them for as short as 15 minutes, maybe an hour, maybe two hours maybe at the beginning of the morning you place them end of the morning put the crown on. Either way there are lots of ways of getting space that don’t involve cutting the teeth. Sometimes you can’t avoid it. You have to cut the teeth.

But even then, you might find some topical. And if you’re very quick with your bur, you can get away with it without having to put local in. Just a reminder, if you are doing a slice, you want to have the cuts that you have at the bottom left of this diagram, you want to have no shoulder, almost like a sharp finish. If you’ve got a shoulder then the tooth can bounce– sorry, the crown can bounce on it. And it obviously won’t fit properly. OK size of the crown. Sizing is a little bit of a learned skill. Something you pick up the more crowns you do. On the whole, is tend to be size fives.

On the whole, if you’ve done a size five on this side, you’re probably going to a size five in all the quadrants. You’ll probably find if you’re used to cutting crowns, and you go to a whole crown you need to use a slightly larger one. That’s to be expected. When you’re sizing it, try not to put it on all the way. Because you put it on all the way, it can be a bit difficult to get off. So just try and kind of put it halfway to work out the size should be. At don’t drop it down the airway. OK.

So sit the patient up, and put some gauze behind the crown, maybe hold it with some tape in the loop as we’re showing here. Don’t drop it. OK. And in fairness, I have to say I’ve not seen anyone drop one down the airway, but maybe it’s just because we’re careful. That’s something you really want to avoid. OK. Finally, we are fitting the crown. Yeah. And you need cement, anything will do. We tend to use a glass ionomer based cement, doesn’t really matter. I would put it on and then get the child to bite on it or even just put it on half way and get them to bite it all the way on.

And when you’re betting them to bite together, I would put some cotton roll in between the top teeth, in between the opposing tooth and the crown and get them to really scrunch down there. All of the cement will squirt out, so use a cotton roll to get rid of all that right away. And then hopefully, if the child would permit you, some floss into proximally to get rid of cement into proximally. And again, if we look at our hints and tips, some of our students have some strawberry toothpaste ready on the back of their hand. And when the child has had the crown on, they just smear that all over to try and take away the taste.

So in conclusion, smaller holes, cooperative children, filling’s are fine. Big holes, uncooperative children, think about whole crowns. Thank you.