Long Span Implant Retained Bridges - Problem With Breaking

[zero_zero]

Why not start using a high performace polymer (pekkton) or titanium instead of zirconium? Are you guys trending this way for large frameworks?

I do quite a few...

 

[ZionDental]

Strongly feel the issue is from verification jig and the torque tension. Need VERY VERY reliable verification jig from doctor first of all if this is not achieved then the torque tension will play huge role in this kind of problem. All that stress is just waiting to explode haha

 

[grantoz]

i think you are using to many different products together and no real education .1st your sirona speed sintering furnace scares me its not designed to do a 13 hour sinter cycle which is what i do for all my full arch cases some of which i did by hand milling 12 years ago no failures by the way. 2nd you are heating and cooling your frame to quickly when firing porcelain to them, again its about an hour each firing.i use zirkonzahn everything for these cases all of it is more expensive to use but no remakes of cases in the mouth make things a lot cheaper when you way up loosing clients. I know i sound like im a ZZ salesman but i have followed there teachings very closely i have done a number of their courses over the years and i have sent my staff there as well there systems work and considering they invented the whole full arch techniques i would think you could do a lot worse than start looking at their systems and investing time and money to make your bridges correctly .A few posts on a site like this isnt going to solve you problems i see so many people try and do this kind of work half assed then it fails then it gives Zirconia a bad name. Im sure John Wilson feels the same hes not having probs either for the same reasons, we have both done hundreds and hundreds of these cases with very few problems .

 

[Gru]

I don't have a lot of these guys' experience with full arch zr cases, but I am really good at trouble shooting and one thing stands out to me:
Are you documenting each step on these? I mean everything down to which ovens and firing times, who handles the product, etc. Even your stone jigs may not be the same from one to the next if they aren't mixed and set the same and some stone even changes slightly over time as it hardens.
There should be a common denominator or maybe more pointing your way to a solution.

 

[BobCDT]

I think John has it right. In research done for connector size of zirconia by 3M some years ago, they developed minimum square MM of connector size and these two cases look like they may not have met the minimum. I would suggest exceeding the minimum. At any rate here is what 3M came up with. Keep in mind, these studies were conducted with 3 unit bridges, not full arches.
Anterior connectors:
Abutment to abutment 7mm sq,
Anterior cantilever 8mm sq
Posterior connectors 12mm

Also when screw retaining a large bridge it's highly likely that the system is under constant load due to our inability to obtain an absolute passive fit with an angulose support structure. Add the fit issue load to the load under function (400-600MPa) and overengineering should be mandatory. I go by the rule of 12mm of interocclusal space or I change the material for these full arch cases. Generally, this gets me 15mm sq minimum. Very often the design will have 30-40 mm sq.

The last point, again to reiterate what John has said, if you cut the interproximal's with a disc after sintering you set the case up for failures exactly like you have photographed. Keep in mind Zirconia is a ceramic and think about how you cut a sheet of glass. It just takes a scratch of the surface.

 

[Beatrice]

If you want to use a different strategy you could use our solution the Diamart that it made exactly to solve this possible problem
A Zirconia framework with a titanium frame inside it.

https://www.pantheradental.com/diamart/

This was develop by Domenico Casione a high-end technician in Cali, right now it been used in some scientific future publication with UCLA.
Let me know if you want to know more.

Otherwise good luck with your problem.

 

[grantoz]

its true the metal bar would solve a lot of your problems but not all. after all the Davis bridge has been around for at least 7 years in Australia using a ti bar with a full contour sleeve on top ,the Montreal bridge came a bit after that check out the ZirkonZahn web site its a proven technique. but unless you know what you are doing the bar doesnt solve everything the Zirconia can still break during manufacturing and in the mouth i have had to remake a quite a few poor copies from other labs not knowing what they are doing. just a warning to the guys out there thinking they can use super trans Zi in the 600-700 mpa range get ready to remake them in prettau as the super trans breaks on full arch cases bar or no bar i have already seen it. its a shame as it looks great .So the secret is learn your material science from the right people not the rep who is trying to sell you something like cheap Zi discs from the factories in china that are supposed to make every ones zi discs .I had one guy tell me the other day that his supply guy in china gets the factory in china that makes ZirkonZahn discs to make his. I replied thats funny ive been to italy and have been in the factory that makes the discs its at the ZZ facility and saw the blocks coming out of the presses etc. Quick as a flash oh they must send the blocks to china for packaging and said oh ive got to take another call. SO BE CAREFUL !!!.

 

[rkm rdt]

I think denture teeth look better than most of those zirconia bridges I've seen.

 

[grantoz]

not after 2 years they dont. i have clients that are upgrading to Davis Bridges[ ZI TI bar hybrid] all the time because of disgruntled patients that have plastic all on 4s and a lot of those patients are making im going to lawyer up kind of noises. you cant sell the patient a temp solution which is what plastic is and insinuate that its a final or a long term solution and think you are going to not have any head aches. If we paid for a new car and the doors fell off we would scream blue murder yet dentists and techs are pushing resin all on 4 solutions and resin full arches where the teeth break they hold all kinds of crap on them and look just plain 5hitty after a while for the same price of a new car. ive heard all the Zi is too hard resin teeth look better it zi overloads the bone its going explode because of low temp thermal degradation crap for years yet after 12 years and hundreds of full arch zi bridges not one patient has said oh gee i wish i had my plastic teeth again not one has broken and the loss of any implants under theses bridges is far lower than with plastic bridges ever with ti bars reinforcing them. sorry for the rant guys but im passionate about this kind of work.

 

[Sda36]

not after 2 years they dont. i have clients that are upgrading to Davis Bridges[ ZI TI bar hybrid] all the time because of disgruntled patients that have plastic all on 4s and a lot of those patients are making im going to lawyer up kind of noises. you cant sell the patient a temp solution which is what plastic is and insinuate that its a final or a long term solution and think you are going to not have any head aches. If we paid for a new car and the doors fell off we would scream blue murder yet dentists and techs are pushing resin all on 4 solutions and resin full arches where the teeth break they hold all kinds of crap on them and look just plain 5hitty after a while for the same price of a new car. ive heard all the Zi is too hard resin teeth look better it zi overloads the bone its going explode because of low temp thermal degradation crap for years yet after 12 years and hundreds of full arch zi bridges not one patient has said oh gee i wish i had my plastic teeth again not one has broken and the loss of any implants under theses bridges is far lower than with plastic bridges ever with ti bars reinforcing them. sorry for the rant guys but im passionate about this kind of work.

Very well said! Thanks[emoji4]

 

[BobCDT]

I think denture teeth look better than most of those zirconia bridges I've seen.

The denture teeth break out of the acrylic or the acrylic breaks off the metal frame. Patients pay big buck for these cases. They don't need or want the teeth to break off. Denture technology and materials were never invented to be anglose. The materials are 80-100MPa flexure strength. Biting forces reach 600MPa. Denture tooth hybrids are engineered for failure. I know I'm about to get bombed with so many saying "I've done hundreds and never had a failure." That's part of the reason I love DLN.
Then there is the group that says "It's better for the restoration to fail than to lose the implants." This is a BS excuse for selecting the wrong materials for the indication. We are NOT losing implants that are connected to full arch zirconia case.
That said, I do agree that some of the denture teeth are probably more esthetic than FZ. However, these patients are either going from old worn out dentures or a mess of a mouth to a new ceramic hybrid. Pleasing the vast majority of these patients esthetically is not problematic. In fact, some cry with joy when the cases are delivered. If we have a very esthetic conscious patient we can always do some buccal layering.

 

[BobCDT]

If you want to use a different strategy you could use our solution the Diamart that it made exactly to solve this possible problem
A Zirconia framework with a titanium frame inside it.

https://www.pantheradental.com/diamart/

This was develop by Domenico Casione a high-end technician in Cali, right now it been used in some scientific future publication with UCLA.
Let me know if you want to know more.

Otherwise good luck with your problem.

Hi Bernard,
Can we go through this a little so I better understand? I see the primary advantages of a milled bar for improved hygiene on maxillary cases. The mandible can be designed to accommodate good hygiene as a one piece restoration. If maxillary cases are designed to be patient retrievable hygiene is much improved and a bar will support this design beautifully. If we have a bar and screw retained prosthesis we lose the added hygiene factor and I'm not sure of the advantage. What are the benefits of the bar in this design? In addition, the large hollowed out part of the superstructure will result in a much thinner ceramic case. That said, I'm not sure if this is a problem as the bar supports the ceramic so flexural strength is likely critical. I think it becomes more about tensile strength. That said, we are adding significant cost to the Rx plan and I'm not sure what we gain.
Thanks in advance for sharing.

 

[rkm rdt]

The denture teeth break out of the acrylic or the acrylic breaks off the metal frame. Patients pay big buck for these cases. They don't need or want the teeth to break off. Denture technology and materials were never invented to be anglose. The materials are 80-100MPa flexure strength. Biting forces reach 600MPa. Denture tooth hybrids are engineered for failure. I know I'm about to get bombed with so many saying "I've done hundreds and never had a failure." That's part of the reason I love DLN.
Then there is the group that says "It's better for the restoration to fail than to lose the implants." This is a BS excuse for selecting the wrong materials for the indication. We are NOT losing implants that are connected to full arch zirconia case.
That said, I do agree that some of the denture teeth are probably more esthetic than FZ. However, these patients are either going from old worn out dentures or a mess of a mouth to a new ceramic hybrid. Pleasing the vast majority of these patients esthetically is not problematic. In fact, some cry with joy when the cases are delivered. If we have a very esthetic conscious patient we can always do some buccal layering.

I said they look better.. My comment was based on esthetics.period!

 

[Beatrice]

Hi Bob,
This product solve 2 major problem at first
1-Screw channel angulation; in a case where you do not want to use (or cannot, lack of availability) a angulated multi-unit or a angulated screw channel milling technique, with this concept implant position is not anymore a matter
2-Long span bridge; obviously by adding a titanium bar we solidify the whole structure and this can allow a better resistance to zirconia fracture.

The concept required to put a "silicone" between to parts to be able to "seal" it and increase hygiene. This concept is interesting for dentist since they can easily remove the zirconia framework with easy screw access (since it positioned by us and not implant position) and they can easily clean, repair and maintain the framework.

I invite you to contact the inventor for more details Domenico Casione, he will love to answer more of your questions if I was not able to answer all of the,

Best

 

[JohnWilson]

The milled bar is a sweet way to solve some of the negatives that FCZ has.

1) The weight is substantially reduced
2) Fitting the zirconia to the cad bases is eliminated TIME saved
3) Full control to block substructure with a liner and a MUCH larger cement area.
4) No single cad base will ever be under tension. Even the best verification can lead to minor inaccuracies especially when using Non eng bases and conical connections.

Negatives

1) Needs more room
2) Much more risk to do a repair post cementation
3) COST
4) Risk of not sealing off the prosthetic as tissue/bone models over time. What do you do when the ti to tissue developed a gap.
5) Did I mention SPACE?

Its just another tool for us that do a bunch of full arches with advanced materials. I am not sure if Bernard's guy "developed" the idea but non the less he is a good, talented and innovative tech for sure.

 

[Beatrice]

Hi John
I agree with you he probably not developed the idea, what he did was to refine a concept and put a patent on specification of this product.
I still think the final result is an optimized version of the concept

 

[JohnWilson]

Hi John
I agree with you he probably not developed the idea, what he did was to refine a concept and put a patent on specification of this product.
I still think the final result is an optimized version of the concept

TRUE TRUE,

I'd like to read what the patent is just for fun but thats not what this tread is about. Anyhow you know I love you Bernard and always love to see you bring more innovative processes to the industry because OPTIONS allow us all to prosper.

 

[BobCDT]

Bernard thanks.
HI John,
I agree with many of your pros and cons, would love to discuss a little more.
1. Weight, we stopped providing conventional hybrid restoration in 1990 due to breakage of teeth and or acrylic. At that time we moved all these cases to porcelain to gold. Some patient with severe bone loss would require 22-23 mm of restorative material. I remember cases that had close to 3 ounces of gold in the casting. That said, we never ever had a patient comment on weight.
4. You're right about the best verification jigs having a possible discrepancy. That said, Isn't it more about tension on the implant-bone interface than the tension on the CAD base?

 

[grantoz]

Bars and Zi tops work really well i have been doing them [davis bridge] for 7 years that i can remember i glue mine together . by the way angulated screw channel has been not much of a problem for a while for 2 reasons 1st you can get the bars milled by companies with asc by astra and neoss just to name a few and 2nd you can get biax screws in multi unit pros screw and direct to fixture at 25 deg so you can correct the angle by about 50 deg.i tried the silicone option at the beginning the dentists didnt like doing it in the mouth and by glueing the zi ti together with the correct primers outside the mouth you did get a bond this made the whole structure stronger and a much better hygenic seal we all remember how cross pinned cases smelt even with silicone inside to seal them off.

 

[grantoz]

By the way John Wilson doing these cases with Ti bar and Zi top [davis bridge] you can reduce the the bulk greatly .I have done cases with only 6-7 mm in height in places the case is going strong for over 5 years now ,you can also save a lot of headaches on the really thick ones doing it this way.I actually charge less for zi ti because its more straight forward and a lot less manufacturing probs.