sidesh0wb0b
Well-Known Member
Donator
Full Member
- Messages
- 5,649
- Reaction score
- 649
sounds like 6mo is faster. hop a plane!2020
sounds like 6mo is faster. hop a plane!2020
Thank you! I'll be ordering some of those.
Thank you! I'll be ordering some of those.
thats why i left that lab. i got feedback things were wrong but i was tightly controlled to NOT modify the CAM or machines for fear of voided warranties and broken machines. so fine you get crowns with wrong bites and thats the and of the story.
what i can now prove beyond reasonable doubt is that the CAM is the biggest source of problems for people doing CADCAM. its a little field of data science called Metrology. download free Metrology software for most purposes on a free restricted Trial basis if you like.
here is a Metrology scan of a bridge, the dark blue is the edges of the designed bridge, while red and yellow and Green areas indicate how off the mill made it. we are comparing a scan of the milled bridge, to the CAD, 3 different tries at the same file.
View attachment 31085 View attachment 31086 View attachment 31087
now, after modifying only the CAM parameters i was able to make that same bridge to this tolderance:
View attachment 31088
this bridge is now perfectly milled to my design.
thats how i know how off it is even before the ceramists judge design and grind the heck out of it for funsies anyway.
I apologize if this is a silly question....how do you scan the milled bridge and create an stl?its GOM inspect, https://www.gom.com/ runs with any scan format. i used stl files. i would have better precision with better file type, but thats a whole other headache.
Does anyone leave zirconia crowns slightly out of occlusal contact and just allow opposing to (slightly; were talking microns not a millimeters here) super-erupt into contact? I know several techs that go this route. I brought it up one time to another tech and he got pretty upset and said "that shouldn't even be an option, you'll never read anyone publishing THAT as a correct technique."
As it turns out, nobody likes grinding zirconia, lab or dentist.. If you've ever happened to drop by the dental office during a crown seat you can almost hear them thinking, "I hope they don't notice the sparks flying off this zirconia." Then you make eye contact... make it awkward for them. You have the option to take it a step further while they're trapped in your gaze... look past their loupes, into their withering soul, and whisper "micro fractures."
any adjustments should be made with full irrigation.Does anyone leave zirconia crowns slightly out of occlusal contact and just allow opposing to (slightly; were talking microns not a millimeters here) super-erupt into contact? I know several techs that go this route. I brought it up one time to another tech and he got pretty upset and said "that shouldn't even be an option, you'll never read anyone publishing THAT as a correct technique."
As it turns out, nobody likes grinding zirconia, lab or dentist.. If you've ever happened to drop by the dental office during a crown seat you can almost hear them thinking, "I hope they don't notice the sparks flying off this zirconia." Then you make eye contact... make it awkward for them. You have the option to take it a step further while they're trapped in your gaze... look past their loupes, into their withering soul, and whisper "micro fractures."
The bridge was already done. I had nothing to do with the design, mill, stain or glaze. The patient was completely unhappy with it so I did what I could to save them from starting all over. Not sure how the work flow is in your area but in mine, no is not an option or kiss that doctor goodbye. You have to make it happen.I understand your reasons Lindsay, but i'm only going to say i really am disappointed in the people here who accept faulty work coming from their machines, accepting it as Normal, and suggesting this is what happens for everyone. this is by far NOT the case for anyone who operates their milling or printing with Quality assurance and standard Quality Control checks in-and-out of the machines.
yes, I understand in this instance its not your bridge, not your mill, that does not mean these checks and balances don't apply. clearly whoever made this bridge for you needs their process examined.
the best way to mill a bridge is *right the first time* not "anything will do, even if i have to grind it"
you should not be accepting product from a machine that does not produce what you asked it to produce.
Measure your product qualitatively and modify the milling parameters to suit. the only part of this process that should be unacceptable is thinking that the machine and the CAM doesn't need modification straight out of the box. the people that do this need to have their products thoroughly examined.
all that being said, the ceramists i used to work with used to swear only by irrigated handpieces for grinding zirconia. as for the tools they used i can't say because i don't really know.
Thanks, CoolHandLuke! I will give it a try!i have an imetric L1 scanner - the workflow is similar to all other box scanners.
i simply scanned it as a waxup, used the top-bottom holder, which held the bridge by its sprue (you can see the sprue sticking out on the bridge) and scanned sequentially first the top, then flipped over for the bottom and the software lined it all up.
to do this in 3shape you'd just need to add extra scans at the end of the scan stage to capture the bottom, but its the same thing.
from there GOM has an interface to walk you through the importing, marking which set of data is to be the control, and which set of data is to be inspected for inaccuracy.
I am not sure why you have to do that if all. The anatomy is done by your computer. All I use is some heartless green stone for contacts if any, diamond inpregnated wheels and glaze.What burs are recommended for grinding on Zirconia? Specifically, cutting in anatomy, bulk grinding, and polishing.