Dentist lacking in removable knowledge

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Macaroni1116

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Hi, I'm a young(er) dentist who is lacking in removable knowledge. What are the most important details that you as a denture technician need to know from the dentist?

1) And what are your thoughts on metal RPD vs flexible?

2) The local lab I use--patients complain that their flexible partials start becoming smelly pretty quickly just after a few years.. Is there a reason why?
 
JMN

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If you know what I'm telling you, forgive me. I'd rather double up on things than overlook somethign that could help you.

For item 2

The simple fact is these things are near never cleaned as they are supposed to be cleaned as frequently as they are to be cleaned.

Also, with flexibles there will always be an unsealed gap between the tooth and the base as the tooth will not chemically bond to Nylon (Valplast/TCS) or to Acetyl Resin (Snow Rock/Flexite). This lack of chemical bond means that anything which decides to move in at the thin gap between the base and the tooth can get there and stay there. This is the cause of the black line effect around denture teeth on flexibles and poorly maintained dentures. The black line is bacterial colonies, their dead, and the food they were shipped on board the SS Saliva.

With any flexible or poured prosthetic there are tiny little channels drilled through the teeth called 'diatorics' and the base material flows through that hole causing mechanical retention of the tooth.

This is also why the teeth will, after being worn down to or past the diatoric, just pop off of the base. In flexibles it is the only way to retain. In poured denture base material the technician can break the glaze of the denture tooth to get a mild chemical bond and assist retention.

Poured acrylic is generally a (MMA Methyl MethAcrylate) vs most non-poured being a PMMA (PolyMethylMthacrylate). MMAs have less bond and weaker bond to other materials where PMMA is what you generally think of which bonds to the teeth strongly enough they should never release without fracturing off.

There is a special cleaner that is a powder and wipes set available for these, but it's a specialty thing made by the flexible makers. If someone doesn't come up with the name of it off the top of their head, I'll go digging later.
 
JMN

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Item 1.

I have no data, this is my thoughts.

I do not like flexibles as long term prosthesis.

Teeth are designed and intended to take all masticatory functional loading. Cast RPD frames are intended to channel the force through the PDL and to bone instead of treating the gingiva as a shock absorber.

I know and respect many technicians with alternate views.
 
bigj1972

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The simple fact is these things are near never cleaned as they are supposed to be cleaned as frequently as they are to be cleaned.

Also, with flexibles there will always be an unsealed gap between the tooth and the base as the tooth will not chemically bond to Nylon (Valplast/TCS) or to Acetyl Resin (Snow Rock/Flexite). This lack of chemical bond means that anything which decides to move in at the thin gap between the base and the tooth can get there and stay there. This is the cause of the black line effect around denture teeth on flexibles and poorly maintained dentures. The black line is bacterial colonies, their dead, and the food they were shipped on board the SS Saliva.

With any flexible or poured prosthetic there are tiny little channels drilled through the teeth called 'diatorics' and the base material flows through that hole causing mechanical retention of the tooth.

This is also why the teeth will, after being worn down to or past the diatoric, just pop off of the base. In flexibles it is the only way to retain. In poured denture base material the technician can break the glaze of the denture tooth to get a mild chemical bond and assist retention.
Resized_20210315_171210_20210315_171504.jpeg
 
JMN

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I do have a truck to put the tooth back on when that exact thing happens.

Cut back the nylon with a scalpel till you reach metal frame.
Use GC Metal Primer II per IFU (grind, AlO2, etc)
Grind to new material on the base/palatal of the tooth.
Fill the gap with cold cure using brush technique.

Do not do this on the first tooth after a clasp without great attention to the preservation of strength of the attachment of the clasp side of the tooth socket. Leave about 1/2 the socket un-touched or you can end up with a zipper effect.
 
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bigj1972

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8 do have a truck 6o put the tooth back on when that exadt thing happens.

Cut back the nylon with a scslpel till you reach metal frame.
Use GC Metal Primer II per IFU (grind, AlO2, etc)
gr8nd t9 new material on the base/palatal of the tooth.
Fill the gap with c9ld cure using brush technique.

Do not do this on the first tooth after a clasp withiut great attention to the preserfation of strength of the attachment of tue clasp side of tye t0oth socket. Leave about 1/2 tue socket un touched or you fan end up with a zipper effect.
Or tell the dentist they got "As Seen on TV-ed ", strip it all off, weld clasp, new teeth in acrylic.

I make flexibles from time to time in house. Time to stop the bleeding with that case. I was just trying to help illustrate your explanation.
 
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JMN

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Or tell the dentist they got "As Seen on TV-ed ", strip it all off, weld clasp, new teeth in acrylic.

I make flexibles from time to time in house. Time to stop the bleeding with that case. I was just trying to help illustrate your explanation.
I don't have the set of gear here to inject, so I have to be inventive with what's on hand.
 
bigj1972

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Hi, I'm a young(er) dentist who is lacking in removable knowledge. What are the most important details that you as a denture technician need to know from the dentist?

1) And what are your thoughts on metal RPD vs flexible?

2) The local lab I use--patients complain that their flexible partials start becoming smelly pretty quickly just after a few years.. Is there a reason why?
JMN has given excellent advise. Flexibles are not a replacement for acrylic or metal. Just another option on the flowchart. They are overly prescribed and made by labs who outsource to another lab. If you really want to do flexibles, you should hook up with a lab that does them in-house, so you have someone to turn to when things go wrong. While they create an esthetic option, they have their own set of problems. Each acrylic, metal, flexible partials have their own advantages and disadvantages. There is no one choice.
 
JMN

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Or tell the dentist they got "As Seen on TV-ed ", strip it all off, weld clasp, new teeth in acrylic.

I make flexibles from time to time in house. Time to stop the bleeding with that case. I was just trying to help illustrate your explanation.
And you illustrated perfectly
 
Flipperlady

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I think Travis should place a legal disclaimer on this site, that while we are a friendly bunch of lab techs, the "advice" we give can not be considered "binding". I would contact the manufacturer of the material for more info and maybe ask if the patient scrubs the flexible partial with toothbrush or anything abrasive, I think there are special cleaners that the manufacturer may be able to recommend.
 
JMN

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I think Travis should place a legal disclaimer on this site, that while we are a friendly bunch of lab techs, the "advice" we give can not be considered "binding". I would contact the manufacturer of the material for more info and maybe ask if the patient scrubs the flexible partial with toothbrush or anything abrasive, I think there are special cleaners that the manufacturer may be able to recommend.
Hi, I'm a young(er) dentist who is lacking in removable knowledge. What are the most important details that you as a denture technician need to know from the dentist?

1) And what are your thoughts on metal RPD vs flexible?

2) The local lab I use--patients complain that their flexible partials start becoming smelly pretty quickly just after a few years.. Is there a reason why?
 
model guy

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It is my understanding that flexibles were never intended to be a permanent solution. Every lab has their own techniques for designing and processing these partials. If the clasping is lower and on the gingival of the tooth, it tends to really beat up on the gums through insertion and removal. I tend to design my clasps to be a little beefier but only to remain of the tooth structure to avoid perio damage. Ditto the lack of chemical bond between the flexible base and the denture tooth used. The teeth rely solely on a mechanical bond. Tight bites should be observed as a contra indication.
 
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Sda36

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Hi, I'm a young(er) dentist who is lacking in removable knowledge. What are the most important details that you as a denture technician need to know from the dentist?

1) And what are your thoughts on metal RPD vs flexible?

2) The local lab I use--patients complain that their flexible partials start becoming smelly pretty quickly just after a few years.. Is there a reason why?
The biggest thing in a
a proper RPD is the rests, properly prepared "After" the guide planes have been developed! Proper path of insertion is imperative to retention also. Proper rests are what maintains vertical position and takes soft tissue damage. out of the equation. Without well seated rests, vertical translation equals all the stuff you don't want to see in a prosthetic.
 
Sda36

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The biggest thing in a
a proper RPD is the rests, properly prepared "After" the guide planes have been developed! Proper path of insertion is imperative to retention also. Proper rests are what maintains vertical position and takes soft tissue damage. out of the equation. Without well seated rests, vertical translation equals all the stuff you don't want to see in a prosthetic.
That being said, flexible's are all some patients will agree to or ware, have to concede at times.
 
Denturepropgh

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My name is Charles Meister and I'm a certified dental technician specializing in complete dentures, working on certification in partial dentures. I have about 15 years clinical experience working with numerous dentists and their patients. The following is a combination of my education, clinical observations, and opinion. So don't sue me.

1. Every time you are treatment planning and prescribing a partial for a patient, you must refer to the Kennedy method of classification of edentulous spaces and figure out which of the classifications relate to your patient. Class 1 and 2, I would never prescribe a flexible partial for, as they are not supported distally. Class 5, I would be sure to have the flexible partial clasp at least 2 teeth in the anterior, IF they are not both periodontically compromised with a hopeless prognosis. If they are, I would have a talk about extraction with a temporary acrylic partial fabricated and used until bone resorption settles down a bit all the while having the patient come in frequently for medicated temporary liners during the healing process. Now that you have those two crappy teeth out of the way, hopefully there will be now a Kennedy Class 3 or 6 classification and you can have some strong vital abutments at both sides of the partial which you can anchor to. Hopeless teeth are just going to cost both you and your patient more time and money in the long run after you need to add teeth and material to an existing partial.

2. A flexible partial, in my opinion, should only be prescribed for a totally tooth-borne replacement, meaning that it needs to be a bridge supported by teeth on both sides (Kennedy Class 3,4, sometimes 5, 6.) Biomechanics shows us time and time again that when a flexible partial is prescribed for unsupported distal extensions, this actually accelerates the rate of bone resorption due to the constant forces of mastication. That's why if I were a dentist, I would much rather prescribe a rpd metal framework with acrylic saddles. You gain the rigidity of the major connector which reduces the forces of mastication on the underlying tissue and bone, and the serviceability of an acrylic partial which can be relined by any dental lab. If esthetics are an issue, (patient doesn't want metal clasps showing) you can have flexible clasps added to the framework before the framework try-in. If the metal rpd has already been inserted and the patient doesn't like the metal clasps, they can be sectioned from the framework and flexible clasps can be added by providing mechanical retention in the existing acrylic, then injecting a thermoplastic in a matrix to form the flexible clasp. The whole shebang is going to be a bit more expensive to both you and the patient, but the benefits are unmatched by the other options. It's seriously the Cadillac of RPD's. Intra/extra coronal attachments are like your Tesla's and Jaguars, and implants are the supercars. Anything less than metal rpd as a final prosthesis is a junk car with a smelly exhaust that's going to destroy the environment if it's not properly maintained.

3. Prepping rest seats and clasp assembly space prior to taking the final impression would be the responsible thing to do for metal and flexible partial prescription. Don't worry about the drilling into a virgin tooth thing, because partials that have rests just lying on top of the enamel create a lot of problems because they get in the way of the opposing buccal/lingual cusp that used to glide around and do its job just fine until you failed to prep rest seats before the final impression and ordered a framework to be made that a technician following the prescription, has to either call you to discuss other options of rest placement or do as the prescription asks and lay the rest on top of the enamel. Then the patient can no longer close all the way, or they change their parafunctional habits to accomodate the rest leading to tmj, muscle fatigue, headaches, malnourishment, and ultimately sadness, confusion, and distrust. Then they come back to you (maybe) and then they have all these new problems, and you have to decide to remove the rest or accomodate it by reducing the opposing cusp(s). Prepping rest seats before the final impression reduces rotational forces on abutment teeth and act as indirect retainers (clasps, I and T bars are called direct retainers) and you should have rests incorporated in the design to offset the damage that an appliance does overtime to the supportive tissues due to bone resorption. It's important to educate the patient of the importance of coming back in 4-6 months for an exam, and if warranted, a reline. You usually can have a lab reline a flexible partial, it's just a pretty tall order and some labs will put up a fight and recommend a new appliance. (Or perhaps they outsource your cases and don't have the equipment to do it) Hmmmm2 Due to the complexity of the lab procedure, you'll probably encounter around the same lab fee for the service, so it comes down to what the patient can afford and if your lab can do it.
 

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