My biggest challange so far

[wwcanoer]

The Case from H!!!

From my perspective, nothing went right on this case. But, it fit perfect, occlusion was right on and looked great!

Restore 5 -- 11 anterior bridge supported by 4 implants. 8 and 10 are supra, 5 and 11 sub gingival, nothing parallel. Number five with an angled stock abutment, the other three were UCLA custom abutment's. Framework was designed with metal centric stops, cast in three pieces out of Aquarius Hard for D.Sign porcelain and laser welded together by different lab down the street. I do an initial wash bake on bridges, followed by dentin build up, and third firing is incisal. After the second bake a crack appeared across the bottom of number nine pontic. Figured I had jostled something, so just ground it off and rebuilt the dentin along with the incisal. But on a third firing, crack reappeared. Okay, maybe I had a sharp edge on my framework, so stripped it all down to start over. Nothing looked obvious, but retouched the pontic surfaced.

Second time around. Crack showed up again! Called up the patient, canceled his appointment and rescheduled.

Stripped the porcelain off again. Took the framework down the street to the other lab to see what they think. Their consensus was maybe I was trying to hang too much porcelain off the tip of the pontic, although I thought it was within normal limits. We decided that they would cast up and weld on a small extension. It would take them a couple of days, but if everything went smoothly I'd still be able to meet the new cement date. So I get the framework back, looks great, I get to work re-stacking the porcelain. So have you guessed where this is going yet? Yup, crack reappeared.

Another consultation. Everybody's scratching their heads. By now, my framework has been through the oven at least 18 times, so I'm thinking it's time to start over again from scratch. Discuss things with the Doctor, and he suggests making it out of the third generation of Bellglass -- Premise Indirect. Fine with me, except that I have to order the required shade materials, which means canceling another appointment.

Strip the bridge down again, and start over using the Premise Indirect. This goes smoothly except that they no longer carry a gingival pink material. . . . but Bisco carries a pink gingival in their Tescera line of indirect composites. So finally, after almost 2 months the case is finally finished. Cemented this last Friday , patient was very happy with the final result, and said it was worth the wait. Of course he didn't know the full story, I just told him that his case was uniquely challenging to design because of the number of implants involved.

In retrospect, I think the big problem was the large metal mass required for that span.

Unfortunately, I didn't get pictures of the framework, just of the finished case before delivery. And in case you're wondering, the fingers you see, are the patient's.

Carol

[sixonice]

I am sure this is a quite obvious question, but did you ever perform a slow cooling procedure on your dentin bakes? I think your right on the money with this case having such a large mass of alloy, that the coefficient of thermal expansion was playing havoc on the porcelain. Doing a slow cool might have helped control the CTE better for you. All in all the case looked really nice and kudos for you sticking with it and seeing it through.

[charles007]

The Aquarius Hard is on the high end of the Cte range for d.sign ,but it is on their compatibility chart ....... Especially on larger cases, I would change alloys and use their d.Sign series alloys...... .......Slow cooling may have saved this remake, if it was waxed correctly...

Pontics are the # 1 place to see checking when the metal is under waxed or wrong cte range..... Having seen checking twice in the same place tells the story for sure.....
Nice looking case !

Charles

[charles007]

Carol
Change alloys so that you want see any checking. I use an alloy thats in the middle to lower range so that I don't have to increase the cooling time on large pontic cases.....

Charles

[wwcanoer]

Hate to admit it, but never thought of long cooling..........Just learned something new!
That's why I love this forum!

Dr wants high gold content metal, thus AqH, my understanding is that the d.sign 98 has to be pickled before putting porcelain on it..not going there.....

Carol

[sixonice]

Originally Posted by wwcanoer

Hate to admit it, but never thought of long cooling..........Just learned something new!
That's why I love this forum!

Dr wants high gold content metal, thus AqH, my understanding is that the d.sign 98 has to be pickled before putting porcelain on it..not going there.....

Carol

I like the d.SIGN 96 alloy for HN yellow. The metal does sacrifice some rich yellow color, but what it gains is a better CTE for the huge cases and better polishability.
The 98 does have to be pickled. I agree with you....just do not wanna go there, smelly, dangerous, extra step etc., etc. Aquarius Hard is esentially the same alloy minus the zinc (the zinc oxide is what is being pickled off).

[CatamountRob]

I like d.sign 96 as well, however when its all done and polished it dosent really look yellow anymore.

[sixonice]

Originally Posted by CatamountRob

I like d.sign 96 as well, however when its all done and polished it dosent really look yellow anymore.

Your right. I liken it to a "tinge" of yellow. If your used to working with an 86% (or higher) gold alloy going to a 75% is going to be a large difference in color (Platinum and Palladium are powerful bleaching metals). It's all about trade-off's. Both kinds are high noble. The 75% gold is going to polish way better, much less expensive and go a bit further because of it's lower density. Really the 86% golds are only going to give you the "richer" gold color.