Maryland bridges in NP metal

[zena]

Hi everyone just wanted some insight how you do things. I had a 6 unit maryland bridge which was casted in NP metal as requested by the Doctor. It was to replace tooth 41 and the Doctor wanted the wings to extend on the
43 42 41 31 32 33. It was waxed in duralay and casted like normal crown/bridge stuff, once casted it looked great until I went to fit it. It warped completely on one side. So it was re-waxed and this time we decided since the wing span was so long, we were going to do a refractory model and wax it on it and cast it on the model just like you would a casting for a partial denture. It worked wonders the fit was perfect like a glove, no warping and it took no time to fit at all, Do you ever have long span maryland bridges warp if so what do you do to prevent it?

 

[Clear Precision Dental]

I've placed a solid plastic sprue connecting the distal ends of right and left sides BEFORE teasing the wax-up off the cast. I do this when doing any long casting, ie. roundhouse fixed frame, many overdenture bars, etc. It means a little more metal finish, however, I cut through these areas with some very fine carburendum discs (like NM slims) and these "cut like buttah."

 

[TheLabGuy]

When doing Maryland bridges in NP, the only accurate way i've found is doing a refractory. Everybody know why Maryland bridges are done in NP?......NP can be etched....However, if you can do NP, you can do Lava, should of done it in All-Ceramic. Will someone clue me in on these tooth numbers chicken is discussing. Chicken we only have 1-32......I know military does it different, as so does the European countries, but I've never heard of numbers in the 40's.

 

[sixonice]

Also, if non-precious alloy is being used, in order for it to ETCH properly & stay cemented down, the alloy should contain 1.0-1.5% Be (Beryllium). Otherwise it must be Tin-Plated which is a pain. Beryllium, as we all know, has been determined to be harzardous unless proper proecessing & suction are used. There are not many Be NP alloys left out there. I know you can still get Rexillium 3 which has Be in it.

 

[TheLabGuy]

Also, if non-precious alloy is being used, in order for it to ETCH properly & stay cemented down, the alloy should contain 1.0-1.5% Be (Beryllium). Otherwise it must be Tin-Plated which is a pain. Beryllium, as we all know, has been determined to be harzardous unless proper proecessing & suction are used. There are not many Be NP alloys left out there. I know you can still get Rexillium 3 which has Be in it.

Interesting, didn't know the Beryllium connection.....thanks

 

[zena]

When doing Maryland bridges in NP, the only accurate way i've found is doing a refractory. Everybody know why Maryland bridges are done in NP?......NP can be etched....However, if you can do NP, you can do Lava, should of done it in All-Ceramic. Will someone clue me in on these tooth numbers chicken is discussing. Chicken we only have 1-32......I know military does it different, as so does the European countries, but I've never heard of numbers in the 40's.

We use Fédération Dentaire Internationale (FDI),in english is "World Dental Federation" a 2 digit numbering system. The chart is from the Doctor's view looking at the patient in front, meaning that the right side on the chart is actually the patients left side in the mouth.

FDI Two-Digit Notation Permanent teeth
upper right _____________ upper left
18 17 16 15 14 13 12 11 _________ 21 22 23 24 25 26 27 28

48 47 46 45 44 43 42 41 _________ 31 32 33 34 35 36 37 38
lower right __________________ lower left

______________________________________________________

Deciduous teeth (baby teeth)
upper right _________ upper left
55 54 53 52 51 _________ 61 62 63 64 65

85 84 83 82 81 _________ 71 72 73 74 75
lower right _________ lower left

The first number indicates what quadrant in the mouth and the second number is the tooth number check the links for a picture of the adult and baby teeth numbered.

http://http://users.forthnet.gr/ath/abyss/FDI%20two%20digit%20tooth%20numbering%20children.gif

http://http://users.forthnet.gr/ath/abyss/FDI%20two%20digit%20tooth%20numbering.gif

 

[zena]

Also, if non-precious alloy is being used, in order for it to ETCH properly & stay cemented down, the alloy should contain 1.0-1.5% Be (Beryllium).

Otherwise it must be Tin-Plated which is a pain.

Beryllium, as we all know, has been determined to be harzardous unless proper proecessing & suction are used. There are not many Be NP alloys left out there. I know you can still get Rexillium 3 which has Be in it.

Just wondering do you have problems with Tin Plating? I find it so quick and easy to do. It's faster than doing and acid etch on NP metals.popcorn

 

[TheLabGuy]

Thanks chicken!!!!!

 

[sixonice]

Just wondering do you have problems with Tin Plating? I find it so quick and easy to do. It's faster than doing and acid etch on NP metals.popcorn

No problems doing it, just another step in the lab. Reminds me of having to "pickle" alloys in acid way back. I just would rather do the Maryland bridge in a etchable NP alloy or zirconia.

 

[DDDental]

Never had problems doing MBs on refractory models using just partial denture's alloy. Sand blasted it with 60 microns Al2O3 and that's it. Very rarely would come back for etching.

 

[DMC]

I pick up salt-crystals with Zap-It. I use plastic as the connector for the span. no wax just yet......I control the flow of the Zap-It with a pre-treatment of Acelorator to the model. You could also put the Zap-It and/or Model in the refridge to slow the flow.

I drop the plastic pattern in Ultra-Sonic with wax-remover from DVA, then hot water to remove the red grease that was holding my salt crystals and melt away the actual salt. Then clean your model and apply regular wax separator, and seal the margins, and wax your pontic(s).

Never warped for me using CyanoAcrylate and plastic as the base structure?

But we now can scan the actual salt! I've tried it and it prints some of the little undercuts.

This technique is used for Nobel Alloy (VA/MD Bridge) because you can't etch Noble as mentioned before, but I do this even with non-Precious and I etch.