Bonding acrylic with teeth problem

[Edy]

I just started to use Perform pouring acrylic to do dentures , i got very beautiful result out of it but after 2 weeks the patient came to my lab with teeth falling from the denture pretty easily , it looked to me at first that it had no bond at all , i did use the perform carbide which does undercuts into the teeth for mechanical bond but that didnot help as well , should i go back to my standard hot vertex acrylic , used it 5 years so far with no problems at all , the only reason i wanted to try perform pouring acrylic is because time , 1 hour instead of 2-3 hours with vertex and boiling water , here i just pour acrylic into my formed mold and put in the pressure cooker for about 15 minutes , and i must say the result looks amazing but what to do , no Michale bond at all , maybe if i cover the cervical area of the teeth will help or the teeth will still be poorly held in ?

 

[AJEL]

I am very familiar with perform, The time is Pour into cool mold bench set 3-5min then 35 min at 60*c, at 3 atmospheres pressure. I use the pressure unit still but use Denplus acrylic. you should be using a tooth bonder, although without the bond I did have good results for over 5 years. What teeth are you using? If you are not boiling clean the teeth how are you cleaning them?

 

[Edy]

I am very familiar with perform, The time is Pour into cool mold bench set 3-5min then 35 min at 60*c, at 3 atmospheres pressure. I use the pressure unit still but use Denplus acrylic. you should be using a tooth bonder, although without the bond I did have good results for over 5 years. What teeth are you using? If you are not boiling clean the teeth how are you cleaning them?

i use the kettle while i hold teeth into a specially made hand holder then after i pour boiling water over all of them very good , i use the steam too , i used this time Mayerson special , very beautiful teeth , usually i use acryrock teeth and arcyLux.


Denplus acrylic is the same like perform ? its pouring acrylic?

 

[AJEL]

Denplus PMMA DenPlus - is very much like and CE with FDA. The color is stable and had same time, temp & pressure needs. The myerson teeth should bond fine I would use a tooth bonder anyway, I have the habit to use the Vitacoll from Vita, I use 85% vita teeth. DenPlus - onne bottle tooth bonder should be kept in refrigerator and will last for years. I keep MMA powder & Liquid in refrigerator.
I use the same tooth sieve & steam. The tooth cutter & bonder.

 

[JohnWilson]

The higher quality of teeth you use the harder it is for the material to soften/etch the bonding surface of the tooth. I have never used a bonder for pour type cases, however I am extremely careful about the preparation prior to processing.

When setting up the case I break the surface of every tooth with a course cross cut carbide whether I have a gob of room to the model or not. On tight bite cases or an immediate I make sure I have at least 1.5 to 2mm worth of acrylic between the model and the denture tooth.

After boiling out the teeth and steam cleaning them I run the same CLEAN wax free carbide bur and roughen the surface. I then take and submerge the teeth in monomer for 30 sec to a minute, before I but them in the mold. Last step is I take a paint brush and paint the exposed surface of the tooth in the mold and let it set on the bench till the liquid evaporates from the tooth. I then put the model in the flask and mix my acrylic and pour. Now here is the most important part, read your instructions on curing time and water temperature, if the water temp is too high it will cure too fast and not allow for an etch of the tooth surface for a good bond.. Also like AJ stated I keep my powder and liquid in the fridge, it allows for a longer pouring time and an longer initial set of the material as it starts to go through its exothermic reaction.

If you are being very clean and time things right and follow instructions the teeth WILL NOT POP out.

Good luck

 

[Edy]

Denplus PMMA DenPlus - is very much like and CE with FDA. The color is stable and had same time, temp & pressure needs. The myerson teeth should bond fine I would use a tooth bonder anyway, I have the habit to use the Vitacoll from Vita, I use 85% vita teeth. DenPlus - onne bottle tooth bonder should be kept in refrigerator and will last for years. I keep MMA powder & Liquid in refrigerator.
I use the same tooth sieve & steam. The tooth cutter & bonder.

I had no idea there is tooth bonders for dentures ,that might help me with this problem, will give it a try to vitacoll thanks for tips Ajel

 

[Edy]

The higher quality of teeth you use the harder it is for the material to soften/etch the bonding surface of the tooth. I have never used a bonder for pour type cases, however I am extremely careful about the preparation prior to processing.

When setting up the case I break the surface of every tooth with a course cross cut carbide whether I have a gob of room to the model or not. On tight bite cases or an immediate I make sure I have at least 1.5 to 2mm worth of acrylic between the model and the denture tooth.

After boiling out the teeth and steam cleaning them I run the same CLEAN wax free carbide bur and roughen the surface. I then take and submerge the teeth in monomer for 30 sec to a minute, before I but them in the mold. Last step is I take a paint brush and paint the exposed surface of the tooth in the mold and let it set on the bench till the liquid evaporates from the tooth. I then put the model in the flask and mix my acrylic and pour. Now here is the most important part, read your instructions on curing time and water temperature, if the water temp is too high it will cure too fast and not allow for an etch of the tooth surface for a good bond.. Also like AJ stated I keep my powder and liquid in the fridge, it allows for a longer pouring time and an longer initial set of the material as it starts to go through its exothermic reaction.

If you are being very clean and time things right and follow instructions the teeth WILL NOT POP out.

Good luck

Very informative John , i think i really understand now what i did the biggest mistake , after i poured the acrylic i put it in the pressure cooker with very hot water , because my brilliant supplier was teaching me about the perform acrylic that u must put it in scuh a hot water until ur hand while in water can stand the heat until the limit you cant suppot the high temp , so from here i am pretty sure because of that no chemical reaction at all has be made there , siiigh ,and secondly i am thankful for ur advice about the fridge , here in israel is very hot , and if so , thats why i had problems with pouring the acrylic into the mold to , it was losing the liquidity factor very fast and becoming a bit harder to pour , thats why i was forced to put more liquid then specified by company , that may cause a bond issue too . Anyway i had problems only with one case so far , will try al this info on next case , perform really gave very beautil result in a very short time , i wish i solve the bond issues to keep build dentures with it.
Thanks john.

 

[lcmlabforum]

There is a good reason and kind of a trade secret why the good old press pack acrylics like L-199 should
have a good 10 min bench set before placing it in the water tank, esp. with 'premium' type teeth with
double/triple cross linked material.
LCM

 

[JohnWilson]

There is a good reason and kind of a trade secret why the good old press pack acrylics like L-199 should
have a good 10 min bench set before placing it in the water tank, esp. with 'premium' type teeth with
double/triple cross linked material.
LCM

I agree, I even take it one step further when I am doing hybrids with very high end teeth I will inject and leave it for 30min before I put it in the water bath.

 

[Edy]

i think i found a bigger problem which gave me poor bonding .
i admit Jhon that since i started to put my stuff in the fridge and follow the steps you talked about i had much better result , but i forgot to do the wax clean carbide you mentioned above , that resulted in small amounts of wax remaining on the teeth which ruined 2 dentures bonds for me . i read again your steps and i made for myself a test , took one tooth cleaned and + carbide cleaning its bond surface ( only on its bottom with no retention at all , and when i talk about bottom i mean only one surface side bottom of tooth connecting with poured acrylic and no bucal / lingual or mis/ dis acrylic on the tooth ) + didnot use any bonding material ... guess what , it came out from pressure cooker one peace , tried with my biggest player to break out the tooth from the acrylic with no success ... main reasons were very hot water in pressure cooker and now i find another reason which is wax remaining on my teeth after i pour boiling water on them and steam them , oh btw i hold them in this plastic thing when i wash them and clean them HEDENT , this thing might leave wax on itself and the teeth , anybody must use this holder too , how you use it correctly for best result ? because i pour boiling water on it and use steam on it and i do it for long time until i think the teeth are wax free , but still after i finish i open it , i take a tooth and i still feel a waxy slipping surface on it , here it comes the wax clean carbide in role and do the job , but still , i want to boil by teeth and get no wax after finish , should i stop using the plastic holder ?

 

[HDL Owner]

No Pour type denture here! I have used it and not truely a time savings. A popoff cost time and travel to pick-up, repair and deliver!!!!!!! How much did you save or are you lucky and get to charge 55$ for a repair? Hight end teeth I roughen with an arbor band before setting and after boil-out coat each tooth with monomer twice before packing and bench set for 30 minutes. YES I do occasionally get pop-offs but do special 2hr turn around when possible to repair. I press pack or inject every denture, even one tooth flippers. 30 years at this and going strong!

 

[DentureDude]

i think one of the best ways to avoid popoffs it to take the time and give every tooth possible a nice big diatoric.

not just a quick jab with the small round burr. yeah its quick and easy and mostly a wast of time.
the hole needs to look like an upside down mushroom with a nice fat neck. the deep part will serve as the undercut to lock it in but the neck is the part that will break so it needs to be fat.

all the popoffs i see coming back (from other labs) thats almost always the problem. a skinny little hole. so please just stop it with the skinny little holes! lol

 

[kcdt]

I cut a trough with an inverted cone. Nice channel with an undercut. If space is limited, I go with a diatoric mushroomed as you describe.

 

[Edy]

No Pour type denture here! I have used it and uely a time savings. A popoff cost time and travel to pick-up, repair and deliver!!!!!!! How much did you save or are you lucky and get to charge 55$ for a repair? Hight end teeth I roughen with an arbor band before setting and after boil-out coat each tooth with monomer twice before packing and bench set for 30 minutes. YES I do occasionally get pop-offs but do special 2hr turn around when possible to repair. I press pack or inject every denture, even one tooth flippers. 30 years at this and going strong!

I think with the press method i couled do 4 dentures at the same time while with pouring i do one by one only , that is indeed slow and main reason which makes me think go back to press