Tight Fit Problem

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omsk

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Hey everyone,

We have this one case that is becoming a headache. We made a few crowns for a new doctor, same patient.

The first issue that comes is that none of the crowns fit in the mouth at all. Doctor says the go in just about 2/3rds of the way. A little puzzled on this we go ahead and make them again on a new impression, new model, etc. Doctor insists we didn't add die spacer because he doesn't actually see it on the model (We just tell him it's done digitally). We look on our side at all possible causes such as proper model work, etc, we even went ahead and calibrated our milling machine.

Second attempt fits a lot better but the crowns are way too tight. We made sure to add even more cement spacer on exocad than the previous time and we even added a little of axial spacing on the settings. Crowns fit well on model and pretty much fall off. Doctor keeps on saying we forgot the die spacer since they go in but they are too tight.

Any ideas what could it be? A little puzzled on this one. His preparations are good, and impression seem good. His impression is on rigid full arch tray where it seems he used putty as a rigid material and light body. I appears to have been done in two steps although we haven't confirmed it.
 
JMN

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Is the mesial and distal areas the problem with seating- too much contact
Or
The prep is seating/bottoming out on the margin way too soon - hole too small.

Big questions, is this the first case you've done with the Doc? Have you had one go through to seating yet? Do you have any idea if he's new from school and you're making his first 'flying solo' crown(s).

I'm not a big fan of double impression methods. Lightbody applied to the teeth and med or heavy in the tray and one insertion seems to work fine, but putting that tray back in a second time and hoping to get it juuuuuust right is asking for trouble in my opinion for most practitioners.

The problem comes from the two impression method possibly can widen the entire everything in the iimpression from the second material causing hydraulic pressure to move things.

Story time:
Had a dentist that would use (no joke) putty matrix material for the 1st imp and then some off the wall heavy body that looked like vinyl and wax had a love child for the second when doing Nobel Snappy pickup impressions. His crowns were always tight. And there was always a 3-8mm step between the layers height. Fun.
 
CatamountRob

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I'd find out if it was done in two steps before I explored any other possibilities.
 
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omsk

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Is the mesial and distal areas the problem with seating- too much contact
Or
The prep is seating/bottoming out on the margin way too soon - hole too small.

Big questions, is this the first case you've done with the Doc? Have you had one go through to seating yet? Do you have any idea if he's new from school and you're making his first 'flying solo' crown(s).

I'm not a big fan of double impression methods. Lightbody applied to the teeth and med or heavy in the tray and one insertion seems to work fine, but putting that tray back in a second time and hoping to get it juuuuuust right is asking for trouble in my opinion for most practitioners.

The problem comes from the two impression method possibly can widen the entire everything in the iimpression from the second material causing hydraulic pressure to move things.

Story time:
Had a dentist that would use (no joke) putty matrix material for the 1st imp and then some off the wall heavy body that looked like vinyl and wax had a love child for the second when doing Nobel Snappy pickup impressions. His crowns were always tight. And there was always a 3-8mm step between the layers height. Fun.

Mesial and distal contacts were not the problem, the crowns fitted as it they were too small. Like you said, hole too small.

Yes, first case I get from this doctor so I cannot say this hasn't happened before with him.

I THINK the doctor has been around for a while although he is fairly young. His practice does seem to be a new office.
 
Car 54

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Get the crowns to fit your dies with enough spacer, then after initial fitting, add die spacer to the prep, confirm them again, and send them out.
This will leave it in the Drs court (as you help them figure it out). It's a bit tongue and cheek, but may help the Dr with their die spacer fixation, excuse.
 
Car 54

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Does the doc use that gawd awful H & H impression technique?

? Letting the base material set, then scooping out the prep area and injecting the light body and re-positing in the mouth?
 
CatamountRob

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? Letting the base material set, then scooping out the prep area and injecting the light body and re-positing in the mouth?
Scooping it out??
It's not a container of Ben and Jerry's Cherry Garcia C54.
Sheesh....
Actually, I have no idea. H&H to me is the .300 H&H Magnum.
 
Car 54

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There is actually a technique where the Drs (probably very few) do that. It becomes like a custom tray, as to supposedly get greater accuracy for the prep.
 
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omsk

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I'd find out if it was done in two steps before I explored any other possibilities.

Does the doc use that gawd awful H & H impression technique?

I'll ask the doctor if this is what he is doing. I'm pretty sure he did take it in two steps but I'll confirm.

He did mention he was looking for a new lab that could give him more consistent results. I haven't really asked what type of problem he's had previously, maybe it's something along this issue.
 
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Get the crowns to fit your dies with enough spacer, then after initial fitting, add die spacer to the prep, confirm them again, and send them out.
This will leave it in the Drs court (as you help them figure it out). It's a bit tongue and cheek, but may help the Dr with their die spacer fixation, excuse.

Ha, that's a great idea. I haven't been able to get it of his head. He seems to think I'm just telling him this to get it out of my way. He keeps on bringing it up thinking it wasn't done or it's just not accurate.
 
PDC

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So he's a "new" account. Why did he decide to use another lab? Same tight fit problem with the last lab? I bet "yes".

If you are not having any issues with other accounts using the same die stone, then I would focus in on his impressions.

Pour up 2 models and fabricate your crown on the one with die spacer and leave the other unpainted. If the doc says it's still tight, tell him to try his temp on the unpainted die. If it's tight then it's coming from his impression technique.

I've seen this tight fit problem before and it usually is the result of the doctor using the putty as a custom tray. Then he injects the wash and reinserts the tray causing a rebound effect due to the material being compressed.

He probably switched labs because he didn't think he was at fault. That impression technique is deceiving...looks great to the user but the devil is in the details.
 
JMN

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Mesial and distal contacts were not the problem, the crowns fitted as it they were too small. Like you said, hole too small.

Yes, first case I get from this doctor so I cannot say this hasn't happened before with him.

I THINK the doctor has been around for a while although he is fairly young. His practice does seem to be a new office.
I'd go with PDC and Car54 's great ideas. Good luck.
 
Mike2

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I am familiar with the technique, but the one I've seen is the Morita tech., popularize by Parkell. It is on Dr's side I have one that uses a similar technique and had this problem last summer. The base putty is setup too much when he/she uses it to pick up the light body imp. material in the mouth. The bugger is it only creeps up in hot summer months sometime or when they change assistants. Time to to exercise your diplomacy and see how much you want to keep this account. Are you scanning the impression or pouring models and scanning. I would try to contact the rep for the material they are using, or buy some imp. material of you choice, heavy and light body and deliver with smile and ask doc to try it. There is a plenty of info online about impression taking your job is to convince them it;s them not you as you must do others work and nobody else is having the issue I would bet.....my 2 cents
 
Getoothachopper

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Look ,we all know the Doc is screwing up on his side . The work around is do what he asks rather than try to fix his problem . Put two thick coats of die spacer on ,a nice additional coat of scan spray . Then you look like the hero when it works and he knows it was the other lab that couldn't get it right. ( I used to do gold crowns for a guy and if you didn't make them 1+mm out of occlusion he would grind the crap out of them, never tried to figure out what he was doing wrong because they really don't ever want to change ) my two cents .
 
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Thanks a lot for the advice :) greatly appreciated

I'll definetly put this tips to use with this doctor and those hard headed ones that just don't take any advice :p:banghead:
Beer
 
Car 54

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? Letting the base material set, then scooping out the prep area and injecting the light body and re-positing in the mouth?

There is actually a technique where the Drs (probably very few) do that. It becomes like a custom tray, as to supposedly get greater accuracy for the prep.

.--------
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I've seen this tight fit problem before and it usually is the result of the doctor using the putty as a custom tray. Then he injects the wash and reinserts the tray causing a rebound effect due to the material being compressed.

Thank you PDC, for confirming this, and explaining it better than my poor attempt. It's probably why few Drs use that technique, and isn't being pushed as when it was first brought up years ago?
 
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