Pro and Con: Cold & Thermoplastic Polymerization

drm313mac

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The "old fashioned" dentures were cold cure systems, the new systems, according to the literature, are thermoplastic. Each has plus and minus. Therefore, please correct me on all points where I am wrong.

First and foremost I want the denture to be homogenous, a continuity of all the same material throughout, and in this regard thermoplastic processing rules. Or does it? Is it the mixing process that gives homogeneity or is it the temperature of cure?

Second, according to the literature the cold cure results in between 5% and 11% distortion (shrinkage) upon polymerization, whereas thermoplastics have < 0.01% distortion. Then again, the literature that cited this was biased, as it is selling Flexite --- research bought and paid for by one company will usually favor that company.
Therefore, does thermoplastic polymerization result in less distortion?

Using engineering principals (undergraduate fields were primarily mathematical physics and engineering physics),common sense tells us that when we heat an item it will expand and when we cool it, it will contract. If item A is heated more than item B, if the items are the same in structure, item A will expand and contract more, usually. Therefore, will not thermoplastic polymerization result in greater distortion?
OR, will thermoplastic processing result in better structure IF that processing remains at a specific temperature? That is, instead of heating the acrylic to 400 degrees F, we do far less, what will be the trade-offs?

I want the denture to have as little porosity as possible. Thermoplastic curing is best here. Correct?

I want no micro-cracks. Here, it seems that how fast the denture cooled determines this. Some labs toss the heated denture into ice water, and based on experience (my brother and I were in the polar bear club),everything gets a whole lot smaller, and cold-cured metal, while harder becomes more brittle as well.

The reasons for all these questions? The answers will determine the equipment lists, as well as the engineering of the lab space.

I thank you in advance.
 
droberts

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Check out Ivocap Injection. It answers all your questions.
 
drm313mac

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Okay, I have now read all three brochures from the Ivoclar website per this system, and it does not answer the questions posed. For example:

1. What temperature is the ideal, and why, assuming we are using this material?

2. If we vary this temperature up or down, what happens at each specific variation?

3. What pressure is the ideal, and why, assuming we are using this material?

4. If we vary this pressure up or down, what happens at each specific variation?

5. What time for polymerization is ideal, and why, for this material?

6. If we vary this timing up or down, what happens at each specific variation?

7. If we use a competitive material, say TCS or Flexite or Diamond D, under these exact specifications, what are the results positive and negative?

8. The complete system mixes, then injects, then polymerizes. By the literature I found no specifics as to the cooling cycle timing, which from an engineering perspective is rather critical that it be done VERY slowly.

9. The literature does not so state the timing by which the material is heated prior to injection, another engineering landmark of some import.

10. The literature does not compare their system with that of others, for or against, leaving the buyer to choose based only upon name recognition. You may recall Dentsply's Triad system, how it would change dentistry, how I for one bought it and later found it was utter crap and poorly manufactured.

I thank you.
 
CatamountRob

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With all due respect, if you want those type of questions answered, your going to need to call Ivoclars tech support people.
 
CatamountRob

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Most of the questions you want answers to, are of no importance to a lab tech. Our responsibility is to follow the manufacturers instructions, period.
Find a system that has a track record, and that's user friendly, from a reputable company and go with it.
 
drm313mac

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CatamountRob,

In that case, I switch gears and ask a different set of questions.

Many here seem to believe in the Ivoclar system, and that is fine. What other systems have you as techs worked with?
The TCS injection system?
Flexite's system?
Nevin's 5400 washout/curing system?
How about the Handler 2010 Denture Curing System?

In searching for the ideal system you MUST have come across some really awesome units as well as some real lemons. Might you then be able to elaborate on what you have found, and why each unit was good or bad, from the practical standpoint of the end-user?
 
CatamountRob

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I think you might consider finding the lab tech you want first, then setting up your lab together.

Would you want someone else setting up your opertories?
 
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araucaria

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Okay, I have now read all three brochures from the Ivoclar website per this system, and it does not answer the questions posed. For example:

1. What temperature is the ideal, and why, assuming we are using this material?

2. If we vary this temperature up or down, what happens at each specific variation?

3. What pressure is the ideal, and why, assuming we are using this material?

4. If we vary this pressure up or down, what happens at each specific variation?

5. What time for polymerization is ideal, and why, for this material?

6. If we vary this timing up or down, what happens at each specific variation?

7. If we use a competitive material, say TCS or Flexite or Diamond D, under these exact specifications, what are the results positive and negative?

8. The complete system mixes, then injects, then polymerizes. By the literature I found no specifics as to the cooling cycle timing, which from an engineering perspective is rather critical that it be done VERY slowly.

9. The literature does not so state the timing by which the material is heated prior to injection, another engineering landmark of some import.

10. The literature does not compare their system with that of others, for or against, leaving the buyer to choose based only upon name recognition. You may recall Dentsply's Triad system, how it would change dentistry, how I for one bought it and later found it was utter crap and poorly manufactured.

I thank you.

Shouldn't worry about all this. Concentrate on building your brand.
Get customers through the door, and give them good stuff. Great if possible, and excellent value for the money.
Get smooth running clinical skills honed, and an experienced tech back-up. 2c.
 
AJEL

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Each system has it's pros & cons. There are several materials, the most common is a PMMA for general denture construction, and there are many fine systems follow the mfg instr they invented the system. We are artists & not a factory that is producing the exact item ea time. If you are interested in Nylon then Flexite is one, CDM, & TCS are others, some here still use the 1950's Valplast, but it is temperamental (a little humidity & you discover how they came up with sponges.) Take into consideration that for the most part Nylons are not relinable, repairable, or easily adjusted. There is also acetal most currently well known for snap-on from Denmat, but can be use like a tooth colored metal partial framework as well. If you are setting up dentures & partial, & Ortho, & C&B find the people first. Go with the system they are successful with, don't expect 1000% as you have probably noticed your impressions may not reach there. If you feel they are remember there is nothing a DDS or Technician can do that a patient cannot mess up.

As for your other comments about the literature have you been to a dental lab show? The literature and instructions are all there & there are usually many classes you should attend before embarking in this industry. As in the case of removable appliances as every patient is individual each cast, ea set up each situation is a little different. We can regularity produce according to quality desired, but there arequality & then there are denture mills that close their good eye when quality checking. I believe many of your questions have been discussed in Removable Formum's for example: Lucitone 199 problem
 
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drm313mac

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CatamountRob,

Let me rephrase, again.

Say I seek out a lab tech to come and work here. Now, as different techs prefer different systems, different techs will choose cold cure versus thermoplastic polymerization, tcs over flexite over sledgehammer acrylic, diamond D over promolux. Now, does it not make sense then for me, the doctor as well as person spending the money, to first learn about the different systems? In this manner, I employ the tech that is right for this practice, from the beginning? Would you not see this as the logical progression?

Now, to ask the last few questions again:

What other systems have you as techs worked with?
The TCS injection system?
Flexite's system?
Nevin's 5400 washout/curing system?
How about the Handler 2010 Denture Curing System?

Let's take this Handler DCU 2010 as an example. It allows me to heat the acrylic to the exact temperature that I want, to set the exact pressure, to set the timing of each phase --- in other words, this system, if it works, allows everything I need a system to do except make the coffee. Do any of you know anything about this system?
Now, have any of you used or seen others use any of these other products? Do any of you know these other machines?
 
drm313mac

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AJEL,

I liked your answer, a lot. For the life of me I cannot find the "Like" button, though.

My impressions are dead on, and yes, I know about Valplast....the hard way. LOL
 
Flipperlady

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Changed my mind. I met a dentist several years ago that was wanting to do pretty much the same thing. He was semi retired and didn't want to work very hard, wanted to come in take impressions and let lab tech do the work while he was out golfing. Sounds great but doesn't work out that way.
How much removeable have you done in the past? If the answer is not much, you may want to reconsider.
 
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rkm rdt

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Maybe you 2 should bite your fingers too.What is the point of your comments?
 
Tom Moore

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To me this looks like if you ask the poochs the right questions they will preform and jump through the hoop. except for two so far anyway.
 
drm313mac

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Flippercentral,

My first practice I owned, and was cosmetic oriented, with surgical. Yes, we did dentures, but not a huge quantity, simply as my clientele were rather upscale.

I worked in Colorado (as an associate) for a dentures only practice, where the only other procedures were extractions. It was Monday - Thursday practice. The dentures quality was decent though low budget, the lab work (in-house) excellent. I did not care for his impressions technique, but the delivered quality and care were good.

I worked in PA for a few months only, and left when I saw the quality being delivered. This was what I would term a bottom-feeder practice, who advertise that their dentures are affordable.
I have spent time with Allcare and was pretty much disgusted with what I saw. Then again, not all practices are the same, and some dentists who work at these places are conscientious, as are the techs, whereas many dentists and techs simply did not really care.

Therefore, to answer your question, yes, I know my dentistry and dentures, yes, my advertising budget will be huge, and yes, I expect to work harder than any technician. I will be there before they arrive and leave after they have. I will be there, at least initially, all 6 days we are open.

I would like to do a few things not done before. For example, communication errors are the most common causes of mistakes, and so I would like to have technicians with me chair-side, with each and every patient. Dental assistants will be there only for the surgeries, and cleaning the ops, and the techs and I will be caring for the patients.
 
AJEL

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I would like to do a few things not done before. For example, communication errors are the most common causes of mistakes, and so I would like to have technicians with me chair-side, with each and every patient. Dental assistants will be there only for the surgeries, and cleaning the ops, and the techs and I will be caring for the patients.

Well Dr I start 0600 and have been working till 0200 for several months now. I took off 1/2 day this Sunday to catch a service. If you pull a technician off the bench to look at every little patient complaint, your production will show it. Communication is a challenge I tottaly agree, I just stopped doing work for 2 young DDS who know it all (I've only been working in labs since 67) I was sending 70% of what they thought were great models back, and now of course they say 5rew U about paying their bill, (I've just finished filling out the small claims forms, & will have a buddy at the Sheriffs office deliver the summons next week. They R over 60days, I'm not in a good mood with sleep deprivation lately, & a migraine.)
I've worked in the situation you describe back in the mid 70's it was nice & kind of fun but unproductive. (Hi Gordon if U see this it's Luckow). The processing units U mention will handle many of the PMMA, follow the proper temperature ramp & cure times I have the Nevin, I've used the Astron, and the Handler is similar in program-ability. If U R leaning toward heat cured PMMA U will find a lot of technicians liking the Diamond D, myself I use Denplus I prefer Dimetharylaate ethylene glycol as an activator rather than the Polymethacrylate-tert-Amyl commonly utilized in PMMA's. In the Clifford allergy reports more individuals are appearing with Amyl reactions.
For UR repairs (ie cold cured) I would suggest U invest in the TCS pressure unit with temperature guage & heat built in, I have 1 as a back up my main unit is a Heedent from Whaledent, but it has been out of production many moons. I hope UR not intending to do that Colorado Same day denture, even a great tech has trouble making those right (just to many short cuts, & flat plane shouldn't be the only choice).
While U were working with technicians with an in house lab, what system were they using?
 
TomZ

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Well Dr I start 0600 and have been working till 0200 for several months now. I took off 1/2 day this Sunday to catch a service. If you pull a technician off the bench to look at every little patient complaint, your production will show it. Communication is a challenge I tottaly agree, I just stopped doing work for 2 young DDS who know it all (I've only been working in labs since 67) I was sending 70% of what they thought were great models back, and now of course they say 5rew U about paying their bill, (I've just finished filling out the small claims forms, & will have a buddy at the Sheriffs office deliver the summons next week. They R over 60days, I'm not in a good mood with sleep deprivation lately, & a migraine.)

Wow..1967 and you still work on 4 hrs of sleep, work 6.5 days a week, and have to work with disrespectful clients who dont pay and dont give you time to maintain a quality level??
Sorry but
AJ-Your a poster child for everything businesses (labs) should avoid.
 
drm313mac

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AJEL,

Well Dr
First, my dame is David. When I taught college classes (fun stuff like calculus),I would begin each semester with "feel free to call me David. Doc and dr are okay, and anything else you want to call me, it must be outside of class," setting the stage for an informal setting.
Therefore, I am not your doctor, and so you need not address me as such. In the ancient Greek, "doctor" means teacher and healer, which is what I am in the clinical setting, but here, in the lab tech forums, am I not the student and you the teacher?
[No, I will not call you doctor]lol

Well Dr I start 0600 and have been working till 0200 for several months now. I took off 1/2 day this Sunday to catch a service.
We will open at 8, and close at 8, Mon - Sat. The extended hours are for those that are working, so they do not have to take off work. I will arrive by 0745 and depart about 2000 hours.
Sunday to catch a service I expect you mean Christian church service?

If you pull a technician off the bench to look at every little patient complaint, your production will show it.
My intent, the technician that works on that case should be with that patient each time that patient is in the office for that one case. For minor adjustments not so much, but I am speaking of the visits prior to the denture being delivered. Do you not know, at least as well as I, how to perform the wax try-in? If anything, it is you who do not need me when chair-side.

I have the Nevin
Model 5400? How do you (really) like it? What are its' quirks, if any, other than cost?

Per the Nevin as well as the Astron, are these units both cold cure as well as heat, by heating the water (I presume)? My real question is, can these be used for the thermoplastics? If the mechanism is by heating the water as compared to only the flask, is not the temperature limited to the maximum temperature of the water?
[You may assume by now I do not know a whole lot about how these machines work]

Denplus
Impact-20? Impact-Plus? DP97? Can the Dimetharylaate ethylene glycol activator work on other acrylics, such as Diamond D, or is it limited to Denplus?

Yes, I was planning on purchasing the TCS unit, and as you stated, not as the primary producer but for repairs. Another technician had made the same suggestion.

I hope UR not intending to do that Colorado Same day denture, even a great tech has trouble making those right
From the book I used in dental school (still in print though a few editions later),Fixed Prosthodontics, pertaining to dentures, "no amount of hard relines may fix an incorrect bite." Meaning, these dentures are prefabricated to one of 5 arch sizes, the dentist (or tech) does the impressions then performs relines, as many as necessary to fit the patient to the denture. This is ass-backwards from what it should be, which is to fit the denture to the patient.
From a medical perspective, this is malpractice as it is rarely possible to make such a denture actually fit correctly.
From a legal perspective, this is malpractice as we are required to so inform the patient if the denture was a pre-fab, which this is.
Affordable Dentures offers several denture choices, none of which are worth a damn (the PA office I was in was such). There lowest cost denture (at least in the office I was in),their "Economy," is a prefab, and no, they are not telling their patients this, and no, seldom do any of these actually fit. They define a failure as them refunding the monies paid, about 12% of all cases, whereas I define a failure as the denture simply does not fit, is truly uncomfortable as a result of the denture and not the patient, or causes trauma to the tissues, and a few other reasons. Under such rules, more than 90% of all dentures that office made were failures.
That is pathetic. Therefore, no, I do not plan on using this One-Step denture. In my opinion, it is a joke, but unfortunately it is a joke being played on unsuspecting customers.

In Colorado, I do not know what brand of PMMA they were using, except that it was semi cold-cured and they complained that Lucitone-199 was far too expensive to use. In other words, the dentist purchased the really cheap stuff, cheap but durable teeth from China, and very low cost acrylic (also from China),which was shipped in 300 pound drums. This dentist had received his training at Kansas, and his dentures training in Missouri, at one of those $150 denture mills. His tech was very competent, so for her to produce what she did using the materials she had to work with, in my uneducated opinion says a lot for her skills. The cure was in a pressure pot, and upon removal from the pot the flasks were dropped in ice-water. I argued that this will cause micro-fractures and distortion from too rapid cooling, they argued that this makes de-flasking much easier.
 
Tom Moore

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Well Dr I start 0600 and have been working till 0200 for several months now. I took off 1/2 day this Sunday to catch a service. If you pull a technician off the bench to look at every little patient complaint, your production will show it. Communication is a challenge I tottaly agree, I just stopped doing work for 2 young DDS who know it all (I've only been working in labs since 67) I was sending 70% of what they thought were great models back, and now of course they say 5rew U about paying their bill, (I've just finished filling out the small claims forms, & will have a buddy at the Sheriffs office deliver the summons next week. They R over 60days, I'm not in a good mood with sleep deprivation lately, & a migraine.)

Wow..1967 and you still work on 4 hrs of sleep, work 6.5 days a week, and have to work with disrespectful clients who dont pay and dont give you time to maintain a quality level??
Sorry but
AJ-Your a poster child for everything businesses (labs) should avoid.

I did that for 30 years and it added at least 15 years to my actual age. The work was never the big problem it was the stress I put on myself by not imposing limits and learning the word NO. The other person is ever happy to hear NO but that is the big part of learning to use that word.
 
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