IMP FGC TYPE III

[dmonwaxa]

Well here’s another. There seems to be a lot of questions on casting. Here is an example of oversized crowns. Note: The doctor was called before the wax up was started and advised about surcharges he would incur; and was given options. He elected to go with FG.

My reasoning on technique: Because of the sheer size of the crowns the diameter of the sprues had to be substantially large. Since a single large sprue was impractical I used three on each crown combined with chill sets. This ensures the combined diameter of the three sprues equal that of a single large sprue. The chill sets 18g, set low on the crowns and small in diameter allows for the solidification to take place very rapidly from that point up the crown to the feeder sprues and to the reservoir where they allow is still molten. As this happens the casting solidifies and shrinks; allowing for the reservoir to supply molten metal to the casting until complete solidification occurs. When done properly the porosity if any will in the sprues in the area of the reservoir on the side opposite the crown as in the picture...perfect. As you can tell by not taking shortcuts and doing it right the first time is the only way to do it. Any questions....

 

[CatamountRob]

Nicely done, I especially like the pigtail vents. Rob

 

[TheLabGuy]

Wow, I like them......hell of a sprue technique you got ahold of there Troy....lol I guess this was to make sure you the gold flowed all the way around that implant. Nice job stud!!!!!! Those implants will last a lifetime for the patient.

 

[dmonwaxa]

Thanks for the kind comments so far CRob and Rob. I got some more of these, I call them my "Dali's" as in Salvadore Dali the artist. The look weird as heck but they work for me. Casting can be a delicate balance, between having too much metal and not enough.

 

[Al.]

Looks like the porosity is right where it belongs in the bottom of the reservoir not on the crowns.

Are those prefab or did you make them your self?

 

[JohnWilson]

Very cool. This is the stuff I love to see. I would never ever of sprued it this way. I love to see a visual of how it can be done differently with such a great result!!!

 

[dmonwaxa]

Thanks John, but if i may ask; how would you have done it? Always nice to get another perspective.

 

[dmonwaxa]

Looks like the porosity is right where it belongs in the bottom of the reservoir not on the crowns.

Are those prefab or did you make them your self?

Al, by prefab. I assume you're refering to the sprues. I could never make geometrically perfect spheres for the reservoir like that.I believe these are modified prefab judging from the curvature of the leads. I just used the spherical portion of the prefabs.

 

[JohnWilson]

Thanks John, but if i may ask; how would you have done it? Always nice to get another perspective.

We use a single sprue with a res. that weighs at least as much as the wax pattern we are casting. We spru on a 45* angel to the thickest part of the pattern. We calculate our wax weight and plug in the numbers to know precisely how much alloy we need to throw. On very large units such as these I may use a vent lateral to the spru.

 

[dmonwaxa]

Conventionally a single sprue at 45* angle yes, but I'm a bit unconventional.jk. Seriously though, did you see the weight of those monkeys, dont think they make sprues that big. All my castings are methodical, all patterns are weighed and the amount of alloy is calculated according with its sg/density. For argument sake what size of sprue were you thinking about?

 

[JohnWilson]

I am generally a cheap SOB when it comes to materials. If I can make it out of utility wax I will . I did not catch that the units were on the scale. I sure hope you made at 35% mark up on the alloy Those were some heavy suckers.

Seriously though we have used prefabed sprues/res from Bredent Renfert and old school Neys over the years. We have had the best luck making out own after weighing our pattern then duplicating the weight.

 

[paulg100]

dmon,

what was the docs reason for opting for fgc on this?

When i see slugs like this now and with the cost of gold, this is just screaming mono emax or zirconia.

 

[dmonwaxa]

dmon,

what was the docs reason for opting for fgc on this?

When i see slugs like this now and with the cost of gold, this is just screaming mono emax or zirconia.

My guess; his reasoning was the resistance to the effect of the occlusal load over implants. He could have achieved the same with a PFM with metal occlusals.

 

[paulg100]

that was untill he got the gold bill

 

[dmonwaxa]

This was done a couple of years ago before the current gold prices. My guess is today would be a completely different story. But honestly he is a classy guy. I've be very fortunate to work with people of this caliber, people who want to do the right thing and whats best for the patient.

However, couple of years ago my FGCs fluctuated and one doc didn't quite like that. He wanted a flat rate for FGCs and I told him I couldn't, he stated he really liked my work and wanted to continue our relationship to which I replied the crns would still be billed out accordingly, and that it was fair, and in accordance with common industry practice. Well I'll just send it out to California, he stated; Go right ahead doc, I replied. So he did; got his bill back on the FGC and it was 15 -20 bucks more. They billed the exact same way I did except their alloy cost billed was 5 bucks higher than I billed per gm. He now wanted me to do his FGCs again. Well doc I told you that you were getting a fair price btw thanks for the information, seem like I need to raise my prices cause everyone knows small labs lack the purchasing power and we just dont get the volume discounts as mega labs. That combined with the individual service you've been getting definitely warrants a price increase. We did a couple after that and I told him I would no longer be able to give him that support because of reorganization. Did not want to ruin a relationship, and now I still get his esthetic work.