Can a Crown Be Replaced Without Your Aligner or Denture Stopping Fitting?
Usually, yes. An aligner is made to the exact shape of your teeth as they were scanned, and a partial denture seats on particular contours. Replace a crown with a different shape and neither fits properly any more. Scanning the tooth before it is prepared and milling the new crown to that same external shape avoids the problem, and because it is milled here it happens in one visit, so there is no weeks-long temporary of the wrong shape either.
Why the fit goes
A clear aligner is not a generic tray. It is made from a scan of your teeth and is designed to grip particular surfaces in order to move them. The fit is tight by design, because a loose aligner does not move anything.
A partial denture is the same idea from the other direction: it rests and clasps on specific contours of specific teeth, and those contours are what hold it in place.
In both cases the appliance was made for the mouth you had. Change the shape of one tooth and the appliance is now built to a tooth that no longer exists — which shows up as an aligner that will not seat, or a denture that rocks.
Copying the shape
The way round it is to record the shape before destroying it. The tooth or the existing crown is scanned first, while it is still intact. That scan becomes the template for the new crown, so what is milled has the same external shape as what came out.
The inside is designed for the prepared tooth underneath, and the outside is a copy. From the aligner's point of view, or the denture's, nothing has changed.
Why doing it in one visit matters here
A crown made at a laboratory means a temporary crown for a week or two. A temporary is made by hand, and it is not the same shape as either the old crown or the new one.
For most people that is a minor inconvenience. For someone mid-aligner it is two weeks of treatment that cannot progress properly, and for a denture wearer it can mean a denture that will not seat for that whole period. Milling the crown in the same appointment removes the temporary phase entirely.
When it is not possible
If the crown has already broken up, or the tooth underneath has fractured, there may not be enough of the original shape left to copy. The same is true if decay has undermined the contours the denture was clasping.
In those cases we will say so, and the honest answer is that the appliance may need adjusting or remaking. Which is worth knowing at the start rather than discovering when the aligner will not go in.
If you wear an aligner or a denture, say so
It is the single most useful thing you can mention when booking. Knowing before the appointment means the scan is taken in the right order and the crown is designed with the appliance in mind, rather than the appliance being discovered afterwards.
Bring the aligner or the denture with you, so the fit can be checked before you leave.
Questions
Will my aligners still fit afterwards?
That is the point of copying the shape, and usually they do. We check the aligner seats before you leave rather than sending you away to find out.
Can this be done if the crown is already broken?
It depends how much of it is left. If enough of the original shape survives, it can be scanned and copied. If the crown has shattered or the tooth under it has fractured, there may be nothing to copy from, and we will tell you that honestly.
Does it cost more than an ordinary crown?
No. It is the same crown at the same fee — the difference is the order things are done in and what the design is based on, not extra work or extra materials.
Should I pause my Invisalign for this?
Usually not, and that is rather the point. Tell us you are mid-treatment and the crown is designed around it. If your orthodontic plan does need adjusting, it is better to know before the crown is made than after.
What if my denture still does not seat properly?
Then it is adjusted. Copying the shape makes that much less likely, but a denture that was already a loose fit beforehand will not be improved by a new crown, and that is worth separating out.