Best way to process Locator Bar Denture?

JonnyLathe

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First one of these. We did a wax try in with teeth and had the locator bar made. Does anyone have a good step by step guide on the best way to process teeth on one of these bars/models?

Thanks!
 
JonnyLathe

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Edit with a picture. I was thinking I wanted to block out the screw holes with putty, make a silicone duplicate, and reset teeth to the duplicate as I'm unsure about processing directly into the master/bar. Am I being overly cautious?
 

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John in Canada

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That's quite the milled bar! Depends if you are press packing or injecting. But, I inject and still do it as follows. Block out under bar and screw holes. Duplicate model with bar. If you can duplicate with hydrocolloid even better, however, I used alginate for years. Measure out proper water and stone vacuum spatulate pour up impression. Add locator caps onto stone model, block out with plaster the bottom lip of the locators. Invest and pack or inject as normal. I've probably done 100 of these in the last 20 years. Good luck!
 
JonnyLathe

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Wow man thank you! I will be injecting with the ivobase. We don't have a vacuum mixer unfortunately. I was thinking of buying some silicone duplicating material to make sure the duplicate cast was as accurate as possible, and I'd thought of investing in a vacuum mixer (I just took over this department and the docs are pretty open to me ordering equipment to match our needs).

As far as blocking out is concerned, I was planning on blocking out the screw holes and undercuts with lab putty. Hopefully that'll do. I'm definitely green when it comes to fixed dentures but eager to learn.

Do you think I can get away with mixing the stone without the vacuum mixer if I use die stone? The biggest thing I was worried about was fitting locator caps to stone for processing if we didn't vacuum mix.

I'm not 100% happy with this bar. It seems a bit bulky to me. Glidewell. I took over this lab (and this case for that matter) from a tech who quit out of the blue. Is it standard procedure to do a full wax-up/try in before the bar is fabricated?
 
John in Canada

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OK, lots going on here. Silicone is a good idea. I use Zhermack double elite. Use a debubblizer and lightly air dry just before carefully pouring. DO NOT use die stone! Die stone is for................................
DIES!
lol. Use type 3 stone for the duplicate model ( the stone that most labs call lab stone or yellow stone, model stone, etc) if no vacuum mixer, ok, just vibrate good to make as dense as possible, and you could put into a pressure pot for 20-30 minutes while it sets. I've never known a lab without a vacuum mixer-either an in house lab or regular dental lab. Basic equipment. BUT, these days, a lab without a vacuum mixer is a digital lab......and yours isn't! Just get a vacuum mixer, lol. The reason why you are to use type 3 stone is that it has give. Type 4 die stone is very hard, for a reason, and brittle. The bar is bulky in my opinion. My concern is the bar extensions past the distal locators. I don't like the angles, and what is the distance past the distal implants? If you're more than 15mm, I'd be concerned for sure, 12mm would be safer. I use ivocap which is similar to Ivobase. Yes, always do a wax up and try in BEFORE fabricating bar. This way the bar manufacturer can scan the denture, and design the bar within the confines of the denture. You should ask to see the design before milling as well, so that you can visualize what you are getting back. If you don't like the design, that is the time to ask kindly for changes. That gets done, you have a looksie again, if more changes need to be made, you ask for more changes until you are satisfied. And, I wouldn't say that the bar is bad, I just see areas that I would want differently, but just like I am giving you instructions and opinions here, another tech likely has a different technique and opinions to mine. The other thing that I like to do is send manufacturer files to the prescribing doctor and bring them in to the loop so that they see what is being fabricated. I only work with prosthodontists that do this kind of work, and they are pretty knowledgable and have a keen eye. Don't stuff the holes full of lab putty! PITA to clean out. If you have round wire casting wax, like 10 or 12 gauge, put a piece of that in the hole almost to the top then use a bit of putty that you can just flick out when you're ready. I just flash over the holes with wax and steam afterwards. Easy breezy. And other undercuts, I still prefer wax-its slower, yes, its what I work with, but I've been in the field probably longer than you have been alive, hahaha. You can certainly use lab putty, its not a way that I have done it.
 
JonnyLathe

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Solid advice. I took over this lab from someone who didn't believe vacuum mixers were necessary, but I'm certainly a fan! I'll definitely make sure to ask to see bar design in the future. And yes, the extension beyond the distal implants seems a bit much to me as well. Thank you for the tip on using wax instead of putty and the pressure pot.

Feeling much more confident about this now thanks to your advice, I truly appreciate it!
 
JonnyLathe

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OK, lots going on here. Silicone is a good idea. I use Zhermack double elite. Use a debubblizer and lightly air dry just before carefully pouring. DO NOT use die stone! Die stone is for................................
DIES!
lol. Use type 3 stone for the duplicate model ( the stone that most labs call lab stone or yellow stone, model stone, etc) if no vacuum mixer, ok, just vibrate good to make as dense as possible, and you could put into a pressure pot for 20-30 minutes while it sets. I've never known a lab without a vacuum mixer-either an in house lab or regular dental lab. Basic equipment. BUT, these days, a lab without a vacuum mixer is a digital lab......and yours isn't! Just get a vacuum mixer, lol. The reason why you are to use type 3 stone is that it has give. Type 4 die stone is very hard, for a reason, and brittle. The bar is bulky in my opinion. My concern is the bar extensions past the distal locators. I don't like the angles, and what is the distance past the distal implants? If you're more than 15mm, I'd be concerned for sure, 12mm would be safer. I use ivocap which is similar to Ivobase. Yes, always do a wax up and try in BEFORE fabricating bar. This way the bar manufacturer can scan the denture, and design the bar within the confines of the denture. You should ask to see the design before milling as well, so that you can visualize what you are getting back. If you don't like the design, that is the time to ask kindly for changes. That gets done, you have a looksie again, if more changes need to be made, you ask for more changes until you are satisfied. And, I wouldn't say that the bar is bad, I just see areas that I would want differently, but just like I am giving you instructions and opinions here, another tech likely has a different technique and opinions to mine. The other thing that I like to do is send manufacturer files to the prescribing doctor and bring them in to the loop so that they see what is being fabricated. I only work with prosthodontists that do this kind of work, and they are pretty knowledgable and have a keen eye. Don't stuff the holes full of lab putty! PITA to clean out. If you have round wire casting wax, like 10 or 12 gauge, put a piece of that in the hole almost to the top then use a bit of putty that you can just flick out when you're ready. I just flash over the holes with wax and steam afterwards. Easy breezy. And other undercuts, I still prefer wax-its slower, yes, its what I work with, but I've been in the field probably longer than you have been alive, hahaha. You can certainly use lab putty, its not a way that I have done it.
Sorry one more question. How are we supposed to accurately articulate the duplicate model? Old tech took a putty matrix with the original upper setup, but that doesn't help me too much as the baseplate/setup doesn't fit over this bar. I guess I could try getting grinding out the baseplate so it fits over the bar, or take a new bite when we try the bar in perhaps?
 
John in Canada

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I don't articulate the model. I take the denture off the master, transfer to duplicate model and lute it to the model. I've never had an issue of not being correct after processing. Of course there is a chance, but its never happened to me. Are your locators in the record base? There could be an issue there. You likely won't get the record base to fit on the duplicate. In my opinion, there isn't really a reason to try in with locators, so a wax record base is the way to go. Then you just take the wax up and transfer no issues. If you have a light cured or acrylic record base, then may be easier to process on the master model. Sad part is you will likely destroy model to recover case. Not the end of the world, but I try to avoid that whenever possible, thats one reason why I process on a duplicate.
 
JonnyLathe

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I guess the problem I'm seeing now is that the denture setup/baseplate doesn't fit over the bar, so I have to wax up straight to the bar to process. It's like the lab that made the bar didn't account for the wax try-in at all, and it was made without approval The locators are occluding with the lower, seems like a mess. Like I said I picked up this case in the middle from a different tech.
 
John in Canada

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I strongly suggest you wax up, and have the doctor do another try in. If the locators are contacting the lower this is obviously a huge problem. The bar manufacturer doesn't really have a way to compensate for the record base, its not their fault. It's possible that the vertical is over closed and that is the reason why the locators are touching the lower. The actual housing only is 1mm higher than the top of the locator, but still need 1-2mm acrylic to cover. Unfortunately, its a poop case from the git go. The placement of the implants is poop, unless there is poor bone in the posterior region, but I kinda doubt it. And theres other problems which is why the bar in the first place.....to correct the problems and be able to extend as far back as possible. On the other hand, off angle locators at 6 and 11 only would be plenty of retention, along with a post dam, patient would be good to go. Unless the idea was a horseshoe denture, then no post dam, and then use the locators in the 8/9 region.
The doctor had to have tried in the bar, and it would be senseless not to try in the set up with the bar. There's too much going on and too much at stake to foul up a case like this. Steady as she goes, mate! One step at a time. You inherited it, now make lemonade out of lemons.
 
Doris A

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I strongly suggest you wax up, and have the doctor do another try in. If the locators are contacting the lower this is obviously a huge problem. The bar manufacturer doesn't really have a way to compensate for the record base, its not their fault. It's possible that the vertical is over closed and that is the reason why the locators are touching the lower. The actual housing only is 1mm higher than the top of the locator, but still need 1-2mm acrylic to cover. Unfortunately, its a poop case from the git go. The placement of the implants is poop, unless there is poor bone in the posterior region, but I kinda doubt it. And theres other problems which is why the bar in the first place.....to correct the problems and be able to extend as far back as possible. On the other hand, off angle locators at 6 and 11 only would be plenty of retention, along with a post dam, patient would be good to go. Unless the idea was a horseshoe denture, then no post dam, and then use the locators in the 8/9 region.
The doctor had to have tried in the bar, and it would be senseless not to try in the set up with the bar. There's too much going on and too much at stake to foul up a case like this. Steady as she goes, mate! One step at a time. You inherited it, now make lemonade out of lemons.
Or chicken salad out of chicken ****.
 
JonnyLathe

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I strongly suggest you wax up, and have the doctor do another try in. If the locators are contacting the lower this is obviously a huge problem. The bar manufacturer doesn't really have a way to compensate for the record base, its not their fault. It's possible that the vertical is over closed and that is the reason why the locators are touching the lower. The actual housing only is 1mm higher than the top of the locator, but still need 1-2mm acrylic to cover. Unfortunately, its a poop case from the git go. The placement of the implants is poop, unless there is poor bone in the posterior region, but I kinda doubt it. And theres other problems which is why the bar in the first place.....to correct the problems and be able to extend as far back as possible. On the other hand, off angle locators at 6 and 11 only would be plenty of retention, along with a post dam, patient would be good to go. Unless the idea was a horseshoe denture, then no post dam, and then use the locators in the 8/9 region.
The doctor had to have tried in the bar, and it would be senseless not to try in the set up with the bar. There's too much going on and too much at stake to foul up a case like this. Steady as she goes, mate! One step at a time. You inherited it, now make lemonade out of lemons.
This was my thought exactly. I convinced the doc to do a try-in Thursday (patient is frustrated and wants the denture before Thanksgiving). I blocked out the bar and made a baseplate, going to open the bite 2mm (I believe it's over closed) and reset the upper (with bar) and lower lower denture try-in and have the patient try it in. Hopefully all goes well and I can get them processed afterwards.

I truly appreciate your help!
 
JonnyLathe

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I strongly suggest you wax up, and have the doctor do another try in. If the locators are contacting the lower this is obviously a huge problem. The bar manufacturer doesn't really have a way to compensate for the record base, its not their fault. It's possible that the vertical is over closed and that is the reason why the locators are touching the lower. The actual housing only is 1mm higher than the top of the locator, but still need 1-2mm acrylic to cover. Unfortunately, its a poop case from the git go. The placement of the implants is poop, unless there is poor bone in the posterior region, but I kinda doubt it. And theres other problems which is why the bar in the first place.....to correct the problems and be able to extend as far back as possible. On the other hand, off angle locators at 6 and 11 only would be plenty of retention, along with a post dam, patient would be good to go. Unless the idea was a horseshoe denture, then no post dam, and then use the locators in the 8/9 region.
The doctor had to have tried in the bar, and it would be senseless not to try in the set up with the bar. There's too much going on and too much at stake to foul up a case like this. Steady as she goes, mate! One step at a time. You inherited it, now make lemonade out of lemons.
 

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John in Canada

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Happy to hear. Bridge delivered yet? You’re nothing until that point, lol!
 

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