Rocking, Rocking, ROCKING!

[TheLabGuy]

I do tons of bridges (at least working on one almost everyday) and I can't think of the last time I've had a bridge rock. Are you using dipping wax then inlay wax? Waxing the margins under a scope or at least double checking under a scope? To answer your question, a 3-unit takes me about 25 minutes to have waxed up and in the ringless sprue-former ready for investment. I never wait like you are doing.....don't have the time, get'em in, make them beautiful and get'em out.

 

[desertfox384]

I do tons of bridges (at least working on one almost everyday) and I can't think of the last time I've had a bridge rock. Are you using dipping wax then inlay wax? Waxing the margins under a scope or at least double checking under a scope? To answer your question, a 3-unit takes me about 25 minutes to have waxed up and in the ringless sprue-former ready for investment. I never wait like you are doing.....don't have the time, get'em in, make them beautiful and get'em out.

I dont dip, I apply a thin layer of ivoclar margin wax on the prep and slightly below the margins, do my waxing up then trim margins under 10x scope, put back on model and wax in pontics. I wax all day, leave everything finished but on the dies until the end of the day then i sprue and pop them off the dies. Maybe thats a mistake? It's just always seemed to make more sense to do it in a batch like that.

 

[TheLabGuy]

I dont dip, I apply a thin layer of ivoclar margin wax on the prep and slightly below the margins, do my waxing up then trim margins under 10x scope, put back on model and wax in pontics. I wax all day, leave everything finished but on the dies until the end of the day then i sprue and pop them off the dies. Maybe thats a mistake? It's just always seemed to make more sense to do it in a batch like that.

Wow, you're doing way too much work. Get yourself some dipping wax and a dip pot. Yeah, that's your problem, you're letting your wax patterns sit too long, and the cut back, add, cut back margins is taking way to long. My waxing technique goes exactly like this.
-I dip the abutment dies
-add inlay wax to margins and where needed to support the porcelain
-fine tune the margins on both dies
Then, time for the pontic
-add a preformed pontic (I have some preformed 10 guage runner bars, I use this as my preformed pontic, much cheaper than the preformed)
-double check path of insertion and double check margins under the scope

Then sprue it up per the beginning of this thread. The only time I ever use the red margin wax is when I'm doing veneers and have to really focus on the margins and it may take me a little time (therefore they don't shrink or warp from sitting so long). Now this doesn't mean you have to invest everything you wax up immediately. I wax up about 10-20 crowns and then invest, but I wouldn't let them set on my bench for more than 2-3 hours and certainly not all day. Hope that helps......get yourself a dip pot/wax, use strictly inlay wax and invest twice or three times a day instead of once a day.

 

[dmonwaxa]

I dont dip, I apply a thin layer of ivoclar margin wax on the prep and slightly below the margins, do my waxing up then trim margins under 10x scope, put back on model and wax in pontics. I wax all day, leave everything finished but on the dies until the end of the day then i sprue and pop them off the dies. Maybe thats a mistake? It's just always seemed to make more sense to do it in a batch like that.

I don't think there is a problem with batching but if you have previously removed from dies after marginating and replaced till the end of the day then that could influence the integrity of the bridge. Fluctuations in ambient temp combined with the memory of spool wax guess what? If you must leave till the end of the day then you may have to use a techinque to keep them seated as stated in a previous post, by using floss and sticky wax. Also when doing your connectors use the tip of a very small instrument like a pkt #1. at the minimum amount amount of heat to allow the wax to "flow" in very small increments.

 

[Al.]

I agree with all the above.

Do yourself a favor and order a dip pot and some dipping wax.
Set your pot temp so you put an even coat of around .4 or 5 and just add on all the thin areas on the corners, and voids, add support cut back to your mark reseal and sprue. 5 to 10 minutes per coping.

Doing it in batches (for me) is the only way to be productive.

Dip them all in a batch.
Add on all the thin spots.

Match the dies to the pans and add support.

Cut them all back in a batch etc etc.

 

[AL1]

Wax weight to gold amount

Does anyone know the formula for figuring out amount of dwt for casting. The one I have is density times wax weight in grams divided by 1.5 gives amount of gold in dwt.

 

[SandRLab]

I'm rocking too!!!

I feel like I am doing the things you recommend and I still can't get a bridge to fit, even a small 3 unit bridge. I do sprue directly to the coping rather than the connector, sometimes one on each cusp if its a big molar. Could that be a factor? I use an oval ring. I seal the pontic(s) to the abutment as the very last with white wax, after the rest of the waxup has cooled, usually several hours. What can I change? Does the amount of gold used to cast affect the fit of the bridge?

 

[TheLabGuy]

I feel like I am doing the things you recommend and I still can't get a bridge to fit, even a small 3 unit bridge. I do sprue directly to the coping rather than the connector, sometimes one on each cusp if its a big molar. Could that be a factor? I use an oval ring. I seal the pontic(s) to the abutment as the very last with white wax, after the rest of the waxup has cooled, usually several hours. What can I change? Does the amount of gold used to cast affect the fit of the bridge?

I don't think where you put the initial sprues is very important (never mattered for me),but make sure you're using a bar to disperse the heating/cooling evenly. I don't know about your white wax, but mine is very soft (it's for carving) and for presentation purposes only. I hardly ever have to go lute my pontic connectors after I have it all waxed up. If you use a preformed pontic/preformed sprue leads as pontics, nothing should be flexing in the wax up. Sometimes I'll have to go touch up a margin after checking the path of insertion but that's it. Hope that helps.

 

[clearH2O]

I don't think where you put the initial sprues is very important (never mattered for me),but make sure you're using a bar to disperse the heating/cooling evenly. I don't know about your white wax, but mine is very soft (it's for carving) and for presentation purposes only. I hardly ever have to go lute my pontic connectors after I have it all waxed up. If you use a preformed pontic/preformed sprue leads as pontics, nothing should be flexing in the wax up. Sometimes I'll have to go touch up a margin after checking the path of insertion but that's it. Hope that helps.

Hi everyone,
To sandRlab,
Did you mean off-white wax?
Your rocking may happen due to removal of your waxing pattern.
If you make one step removal before, try to take two to three little removal steps (smoothing) coping before it completely out of its die. Gently set it back.
Repeat this same little removal technique on the rest of your wax copping on the bridge.
Release stress from dies, keep both hand steady during removal waxing pattern would do the trick to stop warping dedicated wax.
Hope this helps.


Hi TheLabguy, I like your technique of making pontics. I am going to recycle those cut and through away pre-form bars for pontics from now.
thanks

 

[araucaria]

Method of de-vesting could count, size of muffle and position of pattern could count too. Room temperature and cooling speed of wax pattern another point to look at. Size of sprues and connections.
Warm water bath could be used for de-stressing the pattern, lightcure wax could be used for spruing. Length of sprues from funnel to bar should be even. Sprue bar could be made of straight sections instead of horseshoe/curve.
So many variables, just gotta eliminate them one by one over a long period.
Has anyone cast a full arch or large printed pattern ? If there are subsequent distortions then the wax-up process stages should be eliminated from the list of possibilities, and more attention given to spruing. Is it possible to get a printed pattern that has the sprues and cone all done together? That oughta eliminate some aspects.

 

[2oothguy]

I just do a norm wax up and use a piece of thread to make my connection cut. I sprue everything and let it sit and get some singles done or wax a fcc. Then in about 10 min or so i loot together my connections. Wait another 5 to 10 min and pull. Invest with g2 the best investment in the world. (My opinion ) and place in a hot oven cast in 45 min. Tip sandblast it out do not do not knock it out like you may for singles. And prob solved. Connections should be 2mm x 2mm min in wax. I have been doing it this way for 20yrs.

 

[2oothguy]

Does anyone know the formula for figuring out amount of dwt for casting. The one I have is density times wax weight in grams divided by 1.5 gives amount of gold in dwt.

I think it is density times weight of wax up on any metal. Not 100% pos on this but when i wasdoing it i think thats what we did. Oh and i think we added 2 penny weights to the total. Its been a long time since i have done it that way

 

[2oothguy]

That has got to be the ugliest wax up i have ever seen. Sorry but that thing would take forever to finish down to were it needs to be. Why are the connections so thick it looks like one big piece of wax.

 

[TheLabGuy]

That has got to be the ugliest wax up i have ever seen. Sorry but that thing would take forever to finish down to were it needs to be. Why are the connections so thick it looks like one big piece of wax.

Whew!!!!!! For a minute there I thought you were talking about how thick my waist has gotten, but you were talking about my wax up. Which happens when you put the sprue leads at the connectors.

 

[doug]

It sounds alot better than tapping on the underside with a lab knife and a jewlers hammer.

Al, You and John Peters with your Jewelers hammers. He's fixed more bridges than I can remember with that dam hammer.

 

[2oothguy]

Whew!!!!!! For a minute there I thought you were talking about how thick my waist has gotten, but you were talking about my wax up. Which happens when you put the sprue leads at the connectors.

lol

 

[doug]

Does anyone know the formula for figuring out amount of dwt for casting. The one I have is density times wax weight in grams divided by 1.5 gives amount of gold in dwt.

http://www.jensendental.com/alloy/pdfs/charts/Jensen-Wax-Conversion-Chart-6-22-10.pdf

This should help you a little.

 

[dmonwaxa]

http://www.jensendental.com/alloy/pdfs/charts/Jensen-Wax-Conversion-Chart-6-22-10.pdf

This should help you a little.

31 g in 1 Troy oz
20 dwt in 1 Troy oz
#g in 1dwt = 31/20
1dwt = 1.55g
wax weight in g x spg or density (of alloy being used) gives you the amount needed for casting.
ex: wax weight = 1.63 g
sp/density = 14.2
metal needed = 1.63 x 14.2
metal needed = 23.14 gm

from ex above
dwt = 1.63g/1.55g= 1.05dwt

metal needed
1.05dwt = ?g
metal = dwt x sg x g/dwt
= 1.05 x 14.2 x 1.55
= 23.14g

measuring in dwt is antiquated you'll be working backwards converting g to dwt and back again, just use g (gm/grams) that way you dont have to worry about grains etc. Much simpler and more accurate. Its science use scientific units of measurements.

 

[charles007]

Does anyone know the formula for figuring out amount of dwt for casting. The one I have is density times wax weight in grams divided by 1.5 gives amount of gold in dwt.

My formula is so much simpler, its called the Eye Ball Memory Scale.

Eyes look at wax patterns, then quickly look to see how much alloy I have left in my plastic box...... Should I have a lot of ingots, I use more. If I'm low, I cross my fingers.
Worst case scenario, a good casting with short sprues and no button...... Works every time.

Side note, I wax extremely thin since I hate metal finishing, miscast comes about every 3 to 4 months when my coping are around .2 or less.......I'm past due a miscast come to think of it....

No warpage in over 2 years.......

Charles

 

[dmonwaxa]

My formula is so much simpler, its called the Eye Ball Memory Scale.

Eyes look at wax patterns, then quickly look to see how much alloy I have left in my plastic box...... Should I have a lot of ingots, I use more. If I'm low, I cross my fingers.
Worst case scenario, a good casting with short sprues and no button...... Works every time.

Side note, I wax extremely thin since I hate metal finishing, miscast comes about every 3 to 4 months when my coping are around .2 or less.......I'm past due a miscast come to think of it....

No warpage in over 2 years.......

Charles

Dont jinx yourself....cross your fingers; knock on wood,,,,well errr..... forget that

I can pretty much eyeball it myself. If I'm really concerned especially on my large cases then I weigh, but never in dwts always in g/gm.