Heat cure versus cold cure partials

finnster68

finnster68

Yep im an Aussie
Full Member
Messages
137
Reaction score
3
Hi all

I have been in C&B for a long time and am starting to slowly get back into some removable work again.

Just wondering what everyones thoughts are on processing acrylic partials.

I believe heat cured resins are a little stronger but do they provide a closer/better fit as well.

The few that i have done in the past, i have always cold cured because it was "quick" and "easy".

If heat cured is the better way to go then that is the way i will do them from now on.
 
JohnWilson

JohnWilson

Well-Known Member
Full Member
Messages
5,487
Reaction score
1,575
We flask all of our partials, I just choose not to use any cold cure resin for new restorations.

As for fit, most partials that are free end would benefit from the use of a resin that will be the most accurate.

On tooth borne restorations where the intimate fit is more in the metal than the resin it probably has little value.

The reason I choose to use a heat cured resin is the amount of residual monomer that is often present in cold cure restorations.

When I first got started I used a fluid resin system for all my partials. We used a kulzer resin called palapress vario. It was a very fine resin that auto polymerized, but it still was not as good/dense as the cheapest heat cure resin. Just tons faster.

If your asking the question you probably already know the answer.

Heat Cure > Cold Cure

Good luck getting back to removable, its a great segment of this industry that is sadly dieing off, and very few are learning the trade.
 
kcdt

kcdt

Well-Known Member
Full Member
Messages
2,845
Reaction score
632
I employ both methods, it depends on factors such as turn around time, how long the TRP is going to be worn, i.e., say only 6-8 weeks during implant integration, occlusion, number of teeth.
First preference is HC, but I think CC has its place in the tool box.

P.S. In terms of intimacy of fit, the research literature has found CC to be more accurate, its just that the longevity and strength can't match HC. The studies postulate that the heat creates more internal stresses. FWIW.
 
finnster68

finnster68

Yep im an Aussie
Full Member
Messages
137
Reaction score
3
Thanks for the replies guys :)

Tony
 
Brian

Brian

Member
Messages
361
Reaction score
2
I have waffled about this for a few months now.. As refinement continues in acrylics auto cure is not quite what it once was.... Take Pro Base Cold from Ivoclar, that is some tough dense stuff especially when you flask it and cold pack (leaving under the press). Also it's very color stable... Look at Candulor?
Their autoplast is extremely nice and is a standard on the other side of the big pond...

Depending on the saddle area, sometimes I will use the ProBase... Free ends I will Ivocap.. I wouldn't use the pour technique..

I really don't know if there is a right or wrong answer?

If I were to use auto cure as a standard I would definitely look into Candulor's Poly Master. Go to the site and watch the video.. Or maybe Ted could post the video here if that would be okay with Travis?
 
kcdt

kcdt

Well-Known Member
Full Member
Messages
2,845
Reaction score
632
I have waffled about this for a few months now.. As refinement continues in acrylics auto cure is not quite what it once was.... Take Pro Base Cold from Ivoclar, that is some tough dense stuff especially when you flask it and cold pack (leaving under the press). Also it's very color stable... Look at Candulor?
Their autoplast is extremely nice and is a standard on the other side of the big pond...

Depending on the saddle area, sometimes I will use the ProBase... Free ends I will Ivocap.. I wouldn't use the pour technique..

I really don't know if there is a right or wrong answer?

If I were to use auto cure as a standard I would definitely look into Candulor's Poly Master. Go to the site and watch the video.. Or maybe Ted could post the video here if that would be okay with Travis?

I don't think there's any magic bullets out there. Every technique has pros and cons and the choice should be made based on the situation. Any quality material has its place in the toolbox.
I do agree that autocure has come a long way.
 
TomZ

TomZ

Well-Known Member
Full Member
Messages
804
Reaction score
294
Take Pro Base Cold from Ivoclar, that is some tough dense stuff especially when you flask it and cold pack (leaving under the press). Also it's very color stable... Look at Candulor?
Their autoplast is extremely nice and is a standard on the other side of the big pond...


Can you cite any research to support strength or color stability?
Independant testing is a good place to start-
Independant meaning, someone not associated with the manufacturer in regards to grants or product affiliation.

I see alot of pretty packaging and glossy advertisments which project an image, but, having used the products, I do not see a quality difference.

As refinement continues in acrylics auto cure is not quite what it once was....

Auto cure relies on chemical reactions to use up the activator, it also is very fast, so how do long polymer chains develope? Long polymer chains rely on heat and time to form. Its the length of time and continual heat propagation that makes the chains by molecular linkage.
Less strength, less color stability when there are more breaks in the chains.

So how are auto cure resins today different?
 
Last edited:
Clear Precision Dental

Clear Precision Dental

Active Member
Full Member
Messages
507
Reaction score
6
Could it be, they are part of the Obama "auto" bailout plan?

[Sorry, Tom... I had to go for the cheap humor.]

I've always thought of the auto cure resins as the "shrink and stink" group of acrylic. We use it for baseplates, and some repairs but that is about it. It always seemed to be the inferior acrylic because of the residual momomer.

Cytotoxicity Of Denture Base Resins.

Kim SK, Chang IT, Heo SJ, Keak JY.

Department of Prosthodontics, Graduate School, Seoul National University.

The purpose of this study was to investigate the cytotoxicity and mutagenicity of denture base resins. According to manufacturer's instructions, resin specimens were made.

Group 1: heat-polymerizing acrylic resin (Luciton 199(R)).
Group 2: heat-polymerizing acrylic resin containing polyhedraloligosilsesquioxane (POSS esin).
Group 3: auto-polymerizing acrylic resin (Repair Acrylic(R)).
Group 4: direct relining auto-polymerizing acrylic resin (Tokuso Rebase(R)).

Fresh specimens, 24 hrs. and 72 hrs. soaked specimens in distilled water were made. Responses with metabolic assay and mutagenesis assay to eluates from resin specimens were measured. Cultures with medium alone provided controls. Cytotoxicity was assessed with agar overlay test. The results were as follows:

1. Group 4 showed higher cytotoxicity than Group 1, Group 2 and Group 3 in fresh, 24-and 72-hour immersion cases (p<.05). Group 3 showed higher cytotoxicity than Group 2 in fresh cases and showed higher cytotoxicity than Group 1 and Group 2 in 24-and 72-hour immersion cases (p<.05). Group 1 and Group 2 showed no significant difference.

2. All acrylic denture base resins showed significant increase of cell activity as immersion time increased (p<.05).

3. Auto-polymerizing acrylic denture base resins showed higher cytotoxicity than heat-polymerizing acrylic denture base resins (p<.05).

4. All acrylic denture base resins showed lower mutagenicity than controls (p<.05).
 
C

Candulor

Swiss Art of Prosthetics
Messages
23
Reaction score
1
Hey Brian, Thanks for the lob.

Here is an excerpt from a paper written by Candulor Products Manager, Antonio Ferilli. I've attached the complete paper. It's not a sales pitch, just some technical info. I hope you find it interesting.

And if you want to check out the PolyMaster goto Candulor Dental -PolyMaster

Ted Smudde
Candulor

Heat Curing versus Cold Curing Materials
There are continual discussions on the pros and cons of heat and cold curing materials. As a general comment, it can be said that different studies prove that heat curing materials show a lower residual monomer content, better colour stability and better bonding with the acrylic tooth. On the other hand, the arguments in favour of the cold curing material are simpler and faster handling, and the absence of thermal contraction during polymerisation. Figure 4 provides a performance comparison for the two types of material.
From our point of view, it is important to know how to handle PMMA-based acrylics so that we can achieve the optimum in our dental work. (Fig. 4)
 

Attachments

  • Denture Base Artikel Engl.pdf
    116.3 KB · Views: 70
TomZ

TomZ

Well-Known Member
Full Member
Messages
804
Reaction score
294
it can be said that different studies prove that heat curing materials show a lower residual monomer content, better colour stability and better bonding with the acrylic tooth. On the other hand, the arguments in favour of the cold curing material are simpler and faster handling, and the absence of thermal contraction during polymerisation.



Ted appreciate your input, even if the paper was generated by Candulor.
Thanks for confirming what we already know.

Autocure is less strong, has more residual monomer, bonds poorly to teeth, and is less color stable than heat cure resins.
But autocure is faster, and fits better.

Does that mean that it fits better than Ivocap claims?

For your research you may want to have them add that bench setting a packed case of heat cure resin about 20 minutes and a slow heat induction to cure temp will eliminate any chance or porosity. This is because it removes the chance of accelerating the temperature climb rate, due to internal exothermic heat in the mold.



See Skinners "Science of Dental Materials" by Phillips
ISBN 0-7216-7235-3
 
Last edited:
hydent

hydent

Active Member
Full Member
Messages
498
Reaction score
18
For your research you may want to have them add that bench setting a packed case of heat cure resin about 20 minutes and a slow heat induction to cure temp will eliminate any chance or porosity. This is because it removes the chance of accelerating the temperature climb rate, due to internal exothermic heat in the mold.


this will also allow a better chemical bond to the teeth. I have to admit I do not do this but I've never had a problem with porosity either.
 
C

Candulor

Swiss Art of Prosthetics
Messages
23
Reaction score
1
Autocure is less strong, has more residual monomer, bonds poorly to teeth, and is less color stable than heat cure resins.
But autocure is faster, and fits better.

Hey Tom, good to hear from you.

There are different grades of AutoCure depending on the initiator systems used; amine / peroxide or barbituric acid peroxide, as Antonio states in his paper. A premium AutoCure such as ProBase from Ivoclar or Candulor Aesthetic AutoPolymerisat not only cost more but it is a better quality product.

Does that mean that it fits better than Ivocap claims?

Everyone I talk to says Ivocap is the best in regards to dimensional stability and fit. But I have not seen any studies comparing Ivocap vs. premium AutoCure.

Maybe Ivoclar has something comparing their ProBase Cold and Ivocap?

Ted
 
kcdt

kcdt

Well-Known Member
Full Member
Messages
2,845
Reaction score
632
Does that mean that it fits better than Ivocap claims?
ACP in JOP published a reline study that says so...
not that I'm stirring the pot.
 
Brian

Brian

Member
Messages
361
Reaction score
2
ACP in JOP published a reline study that says so...
not that I'm stirring the pot.

Adaptation of acrylic resin dentures polymerized using various activation modes
Authors: T Takamata, Y Inoue, K Hashimoto, S Sugitou, H Arakawa, I Kurasawa
The purpose of this in vitro study was to compare the dimensional accuracy of maxillary dentures made using a conventional heat-activated PMMA resin, a pour resin, a visible light-activated resin, and a microwave-activated acrylic resin. Two simple methods for measuring dimensional accuracy were used: (1) weight of impression material entrapped between the base and master die and (2) measurement of the posterior border gap at five locations. The volume of space between the denture base and the master die was determined by (1) computation and (2) estimation. Statistical analysis (Bartlett, ANOVA and Tukey's Tests) supported the following conclusions: (1) all groups showed a processing contraction, most apparent from buccal flange to buccal flange, (2) the poorest fitting group was processed in a brass flask and a water bath at a temperature which rose from 70 to 100 degrees C, using a heat activated resin (Acron),(3) the visible light activated resin (Triad) produced dentures of intermediate accuracy, as did Acupac 20 wthhen either heat or microwave activated, (4) the two best fitting groups were prepared from a chemically activated resin system using pressure at low heat (PER form),and the resin developed for microwave activation (Acron MC).
Nihon Hotetsu Shika Gakkai zasshi. 01/01/1990; 33(6):1501-11.
ISSN: 0389-5386
 
Brian

Brian

Member
Messages
361
Reaction score
2
Take Pro Base Cold from Ivoclar, that is some tough dense stuff especially when you flask it and cold pack (leaving under the press). Also it's very color stable... Look at Candulor?
Their autoplast is extremely nice and is a standard on the other side of the big pond...


Can you cite any research to support strength or color stability?
Independant testing is a good place to start-
Independant meaning, someone not associated with the manufacturer in regards to grants or product affiliation.

I must admit that my post was anecdotal.. Totally based on my experience.. I have searched for studies on auto cure acrylic before and what I have been able to turn up was scant at best.. No argument here on the chains that accrue during process.... Fact is fact..

My experience; ProBase blew other self cured materials that I have used here in the lab completely out of the water.. Which drew me to the question of employing self cured materials with RPD with in smaller saddle areas, is this appropriate? Example areas with 1 to 2 teeth..

Only study found with ProBase Cold was this on shear bond..

Evaluation of shear bond strength of microwaveable acrylic resins in denture repair: a comparative study
Authors: George Mariatos, Maria Frangou, Gregory Polyzois, Triantafillos Papadopoulos
OBJECTIVE: Acrylic denture base fracture is a common mode of failure. Heat-cured, auto-polymerized, visible light-cured, and microwaveable acrylic resins have been used as repair materials. The aim of this study was to evaluate the shear bond strength of two microwaveable resins (Acron MC and Justi) and one auto-polymerizing acrylic resin (ProBase Cold) as denture repair materials as opposed to a heat-cured one using the non-flasking procedure after thermocycling and photoaging. MATERIAL AND METHODS: Ninety cylindrical specimens were made using the Vertex Rapid Simplified heat-cured acrylic resin. Each repair acrylic resin was poured on the specimen's surface using a cylindrical rubber mold with an internal diameter of 8.5 mm. Thirty specimens for each repair material were made. The control group consisted of 10 specimens from each group which were stored in water for 24 h at 37 degrees C; another 10 specimens from each group were subjected to a thermocycling procedure (5-55 degrees C for 1,000 cycles),while the remaining 10 specimens were subjected to a photoaging procedure. Shear bond strength was measured on a universal testing machine and mode of bond failure was examined under a stereomicroscope. Two-way ANOVA and the Bonferroni post hoc test were performed to identify statistical differences at alpha = 0.05. RESULTS: Justi's shear bond values were significantly inferior to those of ProBase Cold (p 0.05). CONCLUSIONS: ProBase Cold and Acron MC exhibited similar shear bond values. Justi repair material exhibited inferior bond strength compared with that of ProBase Cold and Acron MC. Aging procedures did not affect the bonding properties of any of the repair materials.
Acta odontologica Scandinavica. 01/09/2006; 64(4):244-8.
ISSN: 0001-6357
DOI: 10.1080/00016350600633318
 
Last edited:
JMN

JMN

Christian Member
Full Member
Messages
12,205
Reaction score
1,884
Anyone want to weigh in now with opinions or newer datasets?

Trying to find a good and fast way to explain to a licensee why heat cure and cold cure have different purposes and it's less than ideal to use a pourable cold cure for a definitive prosthesis.

Or have things changed enough in materials science that I'm now wrong?
 
kcdt

kcdt

Well-Known Member
Full Member
Messages
2,845
Reaction score
632
Anyone want to weigh in now with opinions or newer datasets?

Trying to find a good and fast way to explain to a licensee why heat cure and cold cure have different purposes and it's less than ideal to use a pourable cold cure for a definitive prosthesis.

Or have things changed enough in materials science that I'm now wrong?
I would say it depends on the method and quality of the material.
The issue I have is that the typical motivator is cost. So what could make it an acceptable method usually gets cast aside.
Typically, that type of resin works best in that application when it's injected.
Which rules out hydrocolloid
 
JMN

JMN

Christian Member
Full Member
Messages
12,205
Reaction score
1,884
I would say it depends on the method and quality of the material.
The issue I have is that the typical motivator is cost. So what could make it an acceptable method usually gets cast aside.
Typically, that type of resin works best in that application when it's injected.
Which rules out hydrocolloid
This one wanted a cold cure material I used on am iRPD in the dentures because "it was prettier". I had two heads it seemed when I told her it's cold cure poured mateial, it's not intended for definitive prosthesis.
Response:Cold cure? What's that mean?
BangheadBangheadBangheadBangheadBangheadBangheadBangheadBangheadBangheadBangheadBangheadBanghead
 
I

Inna-Hurry

Active Member
Full Member
Messages
395
Reaction score
53
I find it almost annoying that not one of the big A players has anything to add here.
Bottom line here.... FOLLOW MFGRS. INSTRUCTIONS.
 
denturist-student

denturist-student

Well-Known Member
Full Member
Messages
597
Reaction score
103
Hi all

I have been in C&B for a long time and am starting to slowly get back into some removable work again.

Just wondering what everyones thoughts are on processing acrylic partials.

I believe heat cured resins are a little stronger but do they provide a closer/better fit as well.

The few that i have done in the past, i have always cold cured because it was "quick" and "easy".

If heat cured is the better way to go then that is the way i will do them from now on.[/QUOTE
I always heat process the partials with crco, duracetal, or visiclear frameworks.
 
Top Bottom