PROBLEM IN IMPLANT CASTING

[anil patel]

dear friends
we milled implant case from wex blocks but problem is there after casting abutment cavity not open its close ,we try to solve this problem many ways but i cant get result ,
so please suggest me what i should about this problem



thanks

 

[aqdental]

dear friends
we milled implant case from wex blocks but problem is there after casting abutment cavity not open its close ,we try to solve this problem many ways but i cant get result ,
so please suggest me what i should about this problem



thanks

Do you mean the screw acces hole is "closed"?

 

[Gru]

Are you casting to a gold interface UCLA style, or is the entire abutment and interface being cast from milled wax?

 

[anil patel]

dear no we milled cement retain bridge not any screw retain and ucls , i am finding some problem and now tired but cant get it ,


thanks

 

[anil patel]

dear
i attach full arch bridge ,

thanks

 

[bigbrush]

Go withslow heating rate up to 270° C hold 1 hour, go up to 580° C and hold for 1 hourthan to your castingtemp, your problem should be solved.
The wax is mostly mixed with pmma parts that expands. Do not quick heat up ( cast in a hour or something like this) I know time is Money, but doing twice is no profit .

good luck

 

[lcmlabforum]

At least this was milled! Imagine if you had to wax and do all that special connecting procedure all over.
Thank goodness for CAD/CAM.
LCM

 

[Adi]

Yeah I used to have this problem when using pattern resin, and yes it was solved by slow heating, thanks to dln.
I'm still struggling with the fitting problem though, just in implant cases, others are 100% fit , wonder why ?!!

 

[Car 54]

Fitting problems in what way, to tight individually or in bridge cases, to lose, margins not being 100%?
Maybe it's because there is no "wiggle" room with the smaller diameter size of implant abutments, compared to larger prep abutments...I'm only guessing here.

 

[Adi]

Margin fitting and too tight

 

[Car 54]

I've found that with my implants, too. What I had to do was to back off my liquid to water ratio for a bit of a looser fit. In my case, using Microstar, my water to liquid ratio for H.N. metal for crown and bridge is 50/50, 12.5ml of water and 12.5ml of liquid. On my H.N. crowns fitting on implant abutments, I go with less -4 less of water, 8.5ml of water and 16.5 of liquid. So what ever you have worked out for your metals, expansion rate wise, decrease the water, and increase the liquid.

I also paint about 3 coats of die spacer on my lab cast implant abutments above the margins, just so the frameworks aren't so tight in general, and to give place for some cement.

 

[anil patel]

dear
we dont have fitting problem just problem of cavity closing problem ,
i try to many angel but still problem is running ,

thanks
ANIL

 

[aqdental]

dear
we dont have fitting problem just problem of cavity closing problem ,
i try to many angel but still problem is running ,

thanks
ANIL

Make sure investment fills the "cavity" (air maybe trapped) . Do you have a photo?

 

[anil patel]

yes dear i am sure fills hole perfect ,and i have this issue in narrow cavity ,



thanks
Anil

 

[Baobabtree]

yes dear i am sure fills hole perfect ,and i have this issue in narrow cavity ,



thanks
Anil

I agree with bigbrush, heat the ring up slowly to final temp. If there is pmma in the wax block the expansion that occurs when putting the ring in the furnace at final temp will fracture the investment at the shoulder, more so with narrow preps. If you were to take a bur to that area after casting you will find your prep, but you won't be able to salvage the case at that point. Been there and done that.

 

[anil patel]

dear
just really i am in problem my every narrow cavity fills with metal what i should about this problem ,
just need help


thanks

 

[Baobabtree]

What temp are you putting your ring in the burnout furnace?

 

[anil patel]

final tem is 850 and 25 minits hold on 500 tem,

 

[Baobabtree]

do you put the ring in at 0 or 500?

 

[aqdental]

final tem is 850 and 25 minits hold on 500 tem,

Hi Anil, you need a 3 stage burnout (actually 4). You are casting a full arch so I assume you are using either a size 6 or 9 ring = 300/450 gr of investment.
Stage one: cold oven up to 280/290 max and hold between 30/45 min even 1 hour if using 9x with investment with high liquid content (15 cc x60 gr). This stage you are eliminating moisture so the more liquid longer holding. Until there is moister in the ring burnout cannot start. Make sure heat rise is SLOW ( Max 5 deg x min). I'm taking Celsius.
Stage 2 go up to 580/590, 5/7 deg x min and hold 30 min.
Stage 3 go up to 900, 8 deg x min and hold 40 max 60 min than cast ( if your castin temp is 900) otherwise hold 900 x min 20 min than drop by 8 x min (not faster) to your casting temp (850?) than hold for min 30 min/ max 60 than cast.
I know it's a long cycle but a full arch, especially with resin, require time.
BTW what investment are you using?