Forums › Erbium Lasers › General Erbium Discussion › Er:YSGG , ErCr:YSGG and Er:YAG
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Kenneth LukSpectatorHi all,
I’d be grateful if you can clear my confusion over these three lasers.
Some of the studies by Stock et al and also Fried talk about Er:YAG being the better had tissue laser ( larger loss of mass of hard tissue, less thermal build up, less energy required )than Er:YSGG when the same parameters are used on enamel and dentine ablation.
In Manni’s book, he talked about the ErCr:YSGG being a more efficient hard tissue laser than Er:YAG wihtout much references.
Is Er:YSGG same asErCr:YSGG ? What does Cr do ?
When papers compare Er:YAG with Er:YSGG, should we treat it the same as Er:YAG comparing against ErCr:YSGG ?
Er:YSGG = ErCr:YSGG ?
Thanks!
Ken
spider24SpectatorDear Ken,
As far as i know Er:YSGG and ErCr:YSGG are the same. But the correct name is ErCr:YSGG.
If you compare them to Er:YAG there are many different aspects that influence the cutting performance like beam guiding system, spot size, beam profile, application tips, contact / non-contact handpiece and so on.
To make a real comparison it would be necessary to use the same beam guiding + application system behind the laser head.
Olaf
AlbodmdSpectatorI believe the Cr in Er,Cr:YSGG is a dopant that is supposed to increase the absorbance of the wavelength. I haven’t read any studies that actually compare Er,Cr:YSGG to Er:YSGG, so I’m not sure what the actual effect is.
spider24SpectatorQUOTEQuote: from Albodmd on 9:04 pm on Nov. 12, 2005
I believe the Cr in Er,Cr:YSGG is a dopant that is supposed to increase the absorbance of the wavelength. I haven’t read any studies that actually compare Er,Cr:YSGG to Er:YSGG, so I’m not sure what the actual effect is.Yes, i also think thats the reason for the Cr. But i think all YSGG have it.
I know one publication from Keller (University Ulm,Germany). They published that the Er:YAG is faster than the ErCr:YSGG. But they were involved in the development of the Kavo Er:YAG 😉
Olaf
Robert Gregg DDSSpectatorHey Ken,
Just thinking and typing off the top of my head w/o doing any reading up or research into your question, here’s my understanding:
Along with the erbium rare-earth metal ion, the chromium metal ion is added (“doped”) into the molten mix of Yittrium, Scandium, Gallium, Garnet and allowed to cool into form a crystal rod.
The Chromium ion is add to increase the lasing efficiency of the erbium ion alone when the two are combined.
I don’t remember the efficiency increase or the reason why YSGG is preferred over a YAG crystal. I’m sure it is a selection based on measurements made of the two in comparison or the distribution of the ions in the YSGG vs YAG.
I’m pretty sure there was indeed an erbium:YSGG that was used early on before it was discovered that Cr improved the efficiency of the erbium device.
Olaf is correct.
Er, Cr:YSGG at 2.78microns and Er:YAG at 2.94 microns are close enough to each other that other parameters such as pulse duration, repetition rate, peak power are the parameters that modify the dominant tissue interaction of the wavelengths’ primary absorbance effects to make the additional and substantial differences in performance of the different devices.
For example, an Er,Cr:YSGG and an Er:YAG that both operate at 100 microseconds, 4.00 watts and 20 Hz are more likely to be indistinguishable in effects than the same two wavelengths where one is operating at 150 microseconds and the other at 250 microseconds assuming all other parameters are equal.
I don’t have specific data to support that, but I would be surprised if it were otherwise. But that would be the way to do a head-to-head comparison of wavelengths.
Bob
Don ColuzziSpectatorHi Ken: Your confusion is shared by a lot of us. In my attempt to write accurate manuscripts, I do keep coming across Er:YSGG and Er:Cr:YSGG references. For Er:YSGG, Christian Apel in Aachen, Germany uses a 200 microsecond pulsed one all the time, and Dan Fried at UCSF has a q switched one. Strictly speaking, that crystal generates a wavelength of 2.792-2.823 microns. The Er,Cr:YSGG crystal technically generates a wavelength of 2.791; Biolase advertises theirs to emit 2.78, although I don’t know how they do that, given the crystal’s inherent 2.79. When you read the studies, you’ll see everything from typographical errors (J Oral Implantology had a title of “….using the Cr:YSGG laser…” !) to using Er:YSGG and Er,Cr:YSGG interchangeably. Just be aware that there are no commercially available Er:YSGG dental lasers, but there are medical devices with it, as in opthalmic surgery instruments. The Cr is used to add sensitivity to the crystal with resulting increased efficiency, since the lower the wavelength goes from 2940, the slightly less absobance in water. Er:YSGG and Er,Cr:YSGG are not the same, and only Biolase currently has a commercial “Erbium family” YSGG product. Most 2005 studies are using the Biolase unit, at 2.78 microns.
Hope this helps……..DON
Kenneth LukSpectatorThank you all for your input.
I’m not really concerned about which is more efficient as Olaf and Bob described about the effects of all other parameters, also difference in delivery systems; it is confusing to relate the papers with YSGG, CrYSGG.
Karl Stock did a paper comparing the two with same mj/Hz/pulse nos. Not sure about same pd though. Looking forward to your comments on this paper.
Ken
Don ColuzziSpectatorHi Ken: Karl Stock’s paper at SPIE was in presented in January 1997, before Er,Cr:YSGG made an appearance in the marketplace.
His conclusions of the superiority of Er:YAG on wet tissue of course make sense, because of the difference in water absorption.
As I said previously, you should concentrate more on “current” papers. The present thinking on dental hard tissue absorption is that the water component of course has a peak near 2.94, then there’s a smaller OH- “shoulder” at around 2.79, and a higher (than water) peak for phosphate (Calcium phosphate is the basic apatite) around 10 microns plus or minus. (9.6 TEA CO2 is the best for ablating apatite.)
So, for our current technology, “wet” hard tissue has the greatest cutting potential with Er:YAG, but Er,Cr:YSGG is quite good. Most studies with THOSE two wavelengths have shown a higher ablation temperature with Er, Cr:YSGG than with Er:YAG, but those same studies indicate no apparent adverse pulpal effects.
Again, don’t get hung up on the missing “Cr” in the papers; clinically we use Er, Cr:YSGG and Er:YAG; the investigators use other things…….DON
Anyway,
spider24SpectatorHere is the paper from Keller et al. i noticed before. Ken was so kind to email it to me.
http://www.elexxion.com/images/Comparison.pdf
One thing is very important: The comparison was done at one fixed setting for both lasers (300 mJ/400 µs/4Hz). With other settings it might be completly different.
Olaf
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