difference in accuracy (scanners)

DMC

DMC

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Here is a smooth, regular coping from 3M scanner. No collar, no extra anything. Just a basic wussy small scan.

Roughly 5x the data as a 3shape. Maybe even more!!
On the Left, I highlighted the file I have open on the Right side.


ai930.photobucket.com_albums_ad145_turbo2nr_3mscan.jpg
ai930.photobucket.com_albums_ad145_turbo2nr_3mscan.jpg
 
DMC

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Well, I guess you can't see my pic worth a poop.

It is 6,863 KB file for just a coping.

421,644 data points......140,548 total triangles

If you guys could only see what I can see, you'd have a little more insight on this topic. As is, most of you are just guessing at things.
 
TheLabGuy

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Scott, can you get your hands on a file from other scanners to show the differences. I'd really like to see Cerec and Origin myself.
 
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e...w...h

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I'd like to see a fit difference. 3Shape file size has changed over the years... they are smaller now than they were... worse files/scans? I think the answer is certainly no, based on fits. "Better" scans and files may be clear at 60x magnification, but next to nothing at regular size and therefore, the fit difference is next to nothing. There comes a point of diminishing returns and I think 3Shape realizes that and saves lots of time in scan/design by reducing the file size to something that makes more sense in the real world. More efficient workflow vs. "Better" scans that have little or no bearing on the final fits... I think we know what will win the battle.
 
NicelyMKV

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Is 3m white light technology? Im just curious if some of that lack of density in DW and 3shape is the type of technology it is. Red laser as opposed to white light. Is white light able to capture more surface detail? can they both capture the same but one is just sacrificing data density for scan speed. Is it due to the limitations of the milling systems abilities because of bur diameter? Seems like the more the better especially with wax printing.
 
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disturbed

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Prove it. Who cares how many points a scan has? If it works and fits, then that's all the matters. 3Shape has been proven to be one of the fastest there is and produces units that fit perfectly 99% of the time, so who cares about the points? It's all about the software!

It makes logical sense to me that if fit matters to your dentists, points matter, right? If my scan misses a chip at the margin or a sharp tip from an inlay/onlay prep because the scan was not accurate, I imagine our clients would complain.
 
k2 Ceramic Studio

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Not sure why people can't get there head around this, the greater the file size in KB the greater the scan full stop, the more information a scanner can capture and convert into data point/triangles the greater the overall fit. As a 5000+KB scan has maped the area of a prep more than a 1000KB scan. And it's OK to laugh at the science but just wait till that big bridge comes through the door and it takes you two hours to fit it down because the scan capture data was OK for single units and small bridges but when you have divergent preps with undercuts thats when the fun starts. Even with a high end mill unit, if the scan data is limited then the mill will only produce as good as it is given.
Great software is loads of fun to play with but if the scan data is poor then does that not make the software a wast of time.
 
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e...w...h

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Not sure why people can't get there head around this, the greater the file size in KB the greater the scan full stop, the more information a scanner can capture and convert into data point/triangles the greater the overall fit. As a 5000+KB scan has maped the area of a prep more than a 1000KB scan. And it's OK to laugh at the science but just wait till that big bridge comes through the door and it takes you two hours to fit it down because the scan capture data was OK for single units and small bridges but when you have divergent preps with undercuts thats when the fun starts. Even with a high end mill unit, if the scan data is limited then the mill will only produce as good as it is given.
Great software is loads of fun to play with but if the scan data is poor then does that not make the software a wast of time.

Interestingly, we do large span bridges all the time and they drop right into place. NO issues there either. I think a bigger fit factor for large span bridges is oven warpage (although, there are ways to combat this as well).

Sorry guys, it's not about laughing at the science, it's about visually seeing things fit perfectly with both scanners.

I'll say it again, there comes a point of diminishing returns and I think 3shape has found a good balance between file size and efficiency gain.
 
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When I was in physics, professors would always tell us to do a back of the napkin common sense estimate before undertaking any actual calculations. Eg, what would we expect the ballpark to be to achieve clinically acceptable fits. Here is my "back of the napkin" calculation to figure out what an acceptable theoretical "limit" for scanner accuracy and data density should be.

First of all accuracy...we can all agree that we would hope for infinite accuracy or zero uncertainty in our measurements. Granted, for us there is a practical limit at which point we have approximately perfect accuracy and in my opinion, that limit is 1 micron since that is on the order of the diameter of a dentine tubule.

As scott, disturbed and K2 have stated, more data density yields more detail. But EWH and some others have stated that there is a point of diminishing return. Eg, if we are more precise than our manufacuring process...what's the point? But lets say that the manufacturing process is perfect....how many points do we really need? My answer is, as many as needed to resolve the smallest detail we are interested in. Eg, sharp margins, little dips and chips etc. Here is how I would think of it. A new explorer tip diameter is around 100 microns, I would like to be able to scan something half that diameter (eg, the tip will not fall into a hole that size and thereby be undetectable). So, to resolve a 50 micron sphere (or a 50 micron circle in 2d to be simpler),how many points do we need? How about 8 (eg, a stop-sign represents a circle fairly well?). If we space 8 points around the circumfrence of a 50 micron circle, they will each be (50*pi/8) about 20 microns apart. So to me, 20 micron spacing is probably a good limit to aproach if a new explorer is your barometer....but you only need that density at your sharpest features. So, do not be worried if your stl's have wide point spacing on relatively flat surfaces as your software may have smartly thrown them away realizing they are like two state employees doing the same job.

Furthermore, this is how CEREC gets acceptable fits for some docs. If you look at the preparation guidelines, a summary is...."prep so that nothing is sharp and the margins are flat." If there are no sharp curvatures, you can represent an object with sparse point spacing. Scott said before, "what's going on in that 100-200 micron gap between points." And in some cases, the answer is "nothing because my preparation is very smooth and ideal." Other times it's "a whole lot, expect that restoration to bind or be open here."
 
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