Wire embedded in appliance

[CloudPeakDL]

Just got a request for a transitional partial three teeth; 1 bi, 2 first molars on the lower. Dr requests that I put a wire and mesh in acrylic to strengthen it, also wants rests on both 2nd molars 4 c clasps extending from molars.
I have seen where a fracture will occur where the wire is. I think this appliances is over kill but it's what the patient wants. (replacing old appliance).
What are thoughts and opinions on wires embedded in appliances? popcorn

 

[labdude]

I have done several. Both upper and lower. I overlap wires embedded in acrylic for strength. No ton top of each other, more like this (=),but closer together.
I hope that most of these are temporary, supposed to be, will waiting for a bridge etc.
However, I have done repair work on very few. They either hold up very well, or, are used as a temp as they should be IMHO.
The units I have repaired have been quite old, at least 1 year most a lot older. And breakage has mostly been from a pet chewing, car driving over, etc.
Which opens thoughts....if it was in the patients mouth...how do those things happen??
As far as general failure due to design, not to small a number to calculate. I would say I repair about 1 in 3 or 4 hundred due to regular use breakage. And of those, it is usually a lower involving a lack of acrylic because of lingual tori clearence. Still, failure is very rare, but not so, if you don't overlap the wires internally in the applaince.
As for a mesh to strengthen the acrylic, I used to use a SS wire screen years ago. Found it to be just a pain and over time learned it didn't make a difference. If he wants a mesh, maybe try the "fabric type" on the market. I've never used it, but, it seems it would be easier to adapt to the case and not cause it to come out excessively thick.
Mike.

 

[JohnWilson]

I have done several. Both upper and lower. I overlap wires embedded in acrylic for strength. No ton top of each other, more like this (=),but closer together.
I hope that most of these are temporary, supposed to be, will waiting for a bridge etc.
However, I have done repair work on very few. They either hold up very well, or, are used as a temp as they should be IMHO.
The units I have repaired have been quite old, at least 1 year most a lot older. And breakage has mostly been from a pet chewing, car driving over, etc.
Which opens thoughts....if it was in the patients mouth...how do those things happen??
As far as general failure due to design, not to small a number to calculate. I would say I repair about 1 in 3 or 4 hundred due to regular use breakage. And of those, it is usually a lower involving a lack of acrylic because of lingual tori clearence. Still, failure is very rare, but not so, if you don't overlap the wires internally in the applaince.
As for a mesh to strengthen the acrylic, I used to use a SS wire screen years ago. Found it to be just a pain and over time learned it didn't make a difference. If he wants a mesh, maybe try the "fabric type" on the market. I've never used it, but, it seems it would be easier to adapt to the case and not cause it to come out excessively thick.
Mike.

Good advice here. Using wire as reinforcement generally makes an appliance weaker. Prefabbed wire screen mesh does more to hold the two pieces together when it breaks rather than make it stronger. Something rigid is the only thing that offers strength. It has to keep the acrylic from flexing to the fracture point. Something cast that is half the thickness is generally twice as strong as something prefabbed and bent.

When forced to use prefab wire make multiple Z bends to zig zag the wire. When the acrylic covers it it will be harder to flex in one given direction thus making it stronger.

 

[labdude]

To further clairify the success/failure rtae of my design, I do on average 50 or so a year of this type appliance.
Therefore failure rate is about 1 every 3 to 4 years, or more.
These type last a long time.

 

[Brian]

I say the use of wire is a waste of material and the extra 20 sec. to apply..

But if you have to do it? The easiest way is leave the section of wire used for the the clasp a little long and incorporate..

Like John mentioned the wire is good to keep the acrylic together after it breaks.. Same goes for mesh in my book..

 

[kcdt]

If he wants a mesh, maybe try the "fabric type" on the market. I've never used it, but, it seems it would be easier to adapt to the case and not cause it to come out excessively thick.
Mike.

Forget the mesh. All the studies on fiber reinforcement come to the conclusion that the unidirectional fibers are the way to go. Preat Perma Fiber.

 

[CYNOSURER]

I try to tell docs that well made appliances generally break when they no longer fit. If they no longer fit they need to break. Wire mesh, like John says, will hold an appliance together after it breaks, but it will extend the life of an ill fitting appliance because you have to have a layer of acrylic under the mesh, a layer in the mesh and a layer over the mesh so you have a thicker appliance than you need to begin with. So, you get the added benefit of years of use of an overly thick, cumbersome product just so you'll have something stronger that will extend it past its useful life and hold it together when its completely worthless...not that there's anything wrong with that.

 

[araucaria]

Just got a request for a transitional partial three teeth; 1 bi, 2 first molars on the lower. Dr requests that I put a wire and mesh in acrylic to strengthen it, also wants rests on both 2nd molars 4 c clasps extending from molars.
I have seen where a fracture will occur where the wire is. I think this appliances is over kill but it's what the patient wants. (replacing old appliance).
What are thoughts and opinions on wires embedded in appliances? popcorn

just wondering, anyone ever use wrought clasps with a flexible/nylon major connector ? The issue of strength is resolved, as is the tooth support and effective clasping. I know it seems strange but i guess somebody must do it.
BTW i don't have any intention of doing it this way and never have, it just seemed to be an interesting point to throw in for discussion - after all we are the doc's problem solvers.

 

[droberts]

If the doctor and patient demand the use of wire. Apply
a thin layer of GC metal primer on the wire before processing. I do this
routinely with all metal/acrylic cases.