Effects of water flow on dental hard tissue ablation using E

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October 15, 2003 at 11:47 pm #3227 Reply

Anonymous
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J Clin Laser Med Surg. 2003 Jun;21(3):139-44. Related Articles, Links

Effects of water flow on dental hard tissue ablation using Er:YAG laser.

Kim ME, Jeoung DJ, Kim KS.

University Dental School, Chunan, Choongnam, Korea. meunkim@dku.edu

OBJECTIVE: The aim of this study was to investigate the effect of water on dental hard tissue ablation using Er:YAG laser as it relates to energy and pulse repetition rate, and determine the water flow rate that produces the most effective ablation at a given irradiation condition. BACKGROUND DATA: Er:YAG laser application leads to volumetric expansion and micro-explosions that result in hard tissue ablation. Ablation efficiency is improved when combined with fine water spray. MATERIALS AND METHODS: Extracted, healthy human molars were sectioned into two pieces and categorized into small groups related to water flow rate (1.69, 6.75, and 13.5 mL/min), pulse energy (250 and 400 mJ), and pulse repetition rate (5, 10, and 20 Hz). Within the combination of irradiation parameters, a laser beam was applied over enamel and dentin surfaces of the specimens, and the ablation amount was determined by differences in weight before and after irradiation. RESULTS: At a pulse energy of 250 mJ, the most effective ablation resulted from a water flow rate of 1.69 mL/min in both enamel and dentin. With 400 mJ/pulse, dentin removal was most effective at the water flow rate of 1.69 mL/min, whereas the efficiency of enamel ablation was the highest at 6.75 mL/min. Dental hard tissue ablated better as energy and pulse repetition rate increased. CONCLUSION: Effective ablation of dental hard tissue using Er:YAG laser requires that the appropriate water flow rate correspond properly to irradiation conditions. The results of this study suggest the following parameters; a water flow rate of 1.69 mL/min for enamel and dentin ablation at a pulse energy of 250 mJ and for dentin ablation at 400 mJ/pulse, and a water flow rate of 6.75 mL/min for enamel ablation at a pulse energy of 400 mJ, regardles] s of pulse repetition rate of 5, 10, and 20 Hz.

Can you er:YAG guys set water flow on your machines or is it air and water percentages like the er,cr:YSGG?

October 16, 2003 at 2:43 am #9425 Reply

dkimmel
Spectator

Ron , That is one feature that Delight needs to work on. The water adjustment is just like with a high speed handpiece. Biolase did a nice job with that feature. Now if we could get them to make a handpiece like Delights !!!
David

October 16, 2003 at 5:42 am #9431 Reply

Glenn van As
Spectator

I agree with David that the water is not controllable much other than a nice spray. I will measure how much water spray I get tomorrow and I NEVER use more than 250 mj so I should always use 1.69 ml /min.

I guess what they are saying is that with higher energies more water is needed. I just get a fine spray and will check tomorrow to see how many Ml / min but I bet mine is closer to 6 ml or higher.

Glenn

October 16, 2003 at 8:08 pm #9438 Reply

Swpmn
Spectator

Can you er:YAG guys set water flow on your machines or is it air and water percentages like the er,cr:YSGG?

Interesting study but man 400 mJoules??? Good thing these teeth were extracted!!!! What’s the H20 content of enamel and dentin on extracted teeth soaked in a sodium hypochlorite/water solution vs. a vital, in the mouth tooth? Water content of enamel is low anyway but it’s full of hydroxyl groups which should respond to the erbium wavelengths.

The DELight Er:YAG has a pop open door on the front where you can separately adjust the air and water flow with a dial similar to what Dave Kimmel described with our high speed turbines/electrics:

[img]https://www.laserdentistryforum.com/attachments/upload/williamsa101603-1.JPG[/img]

DELight users cannot quantify the air or water flow rate with a “milliliter/min” or “percentage” as with the Waterlase. This is an area where the Waterlase beats the DELight by providing quantifiable settings for feedback to colleagues but I think this could be improved by a milliliter per minute reading vs. a percentage which really doesn’t mean anything other than a reference point. Milliliters of water per minute readout will be a prominent feature in the free-running, digital, variable pulse duration Erbium:YAG that Robert Gregg and myself are currently developing.
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(Just kidding!!!)

When ablating in vivo teeth with either the Waterlase or the DELight, I am achieving success using the lowest water setting which will irrigate/cool the target site and allow me the best(magnified 4.5X Glenn) visibility. With the Waterlase Er,Cr:YSGG I am now experiencing my greatest no anesthesia rates using a keyboard setting of 2.75Watts(20 Hz, roughly 135 mJoules) and 11% water. This is without any pre-treatment/attenuation of the tooth in a defocused mode. For my preliminary osseous recontouring cases I’m using the Er:YAG with high water irrigation rates to provide heat sink insurance.

Al

October 17, 2003 at 1:43 am #9427 Reply

dkimmel
Spectator

Al. 11% water! I am down to 2.5W , 60%A and 20%water. If I drop below 20% water I start to get char in a focused mode on enamel. I am not sure how standardized these % are between lasers.
If Delight had the air and water controls of the Waterlase, the waterlase had the handpiece , the tips and the calbration abliity of the delight and both of them had a print out of the settings used on each patient, that would be a pretty cool laser.
David

October 17, 2003 at 3:21 am #9439 Reply

Swpmn
Spectator

Dave:

With the Waterlase, at 2.75 W and my low 11% water setting, I’m not seeing char but I’m using a much more defocused ablation technique at 1.5mm like Colonna showed us in Atlantic City. Still have lots of irrigation on ablation site even at 11% setting. There are many individual differences with erbium units as Boholst and I have already discovered.

Al

October 17, 2003 at 5:03 am #9432 Reply

Glenn van As
Spectator

Cool stuff…….why dont you run the laser for 1 minute at 11% and collect the water. Then suction it out with a syringe and figure out the ML per min of water spray.

I will not adjust my laser and see what my water ml is…….

Tomorrow I have a hands on so let me see how it is……

glenn

October 17, 2003 at 4:33 pm #9437 Reply

Robert Gregg DDS
Spectator

“Milliliters of water per minute readout will be a prominent feature in the free-running, digital, variable pulse duration Erbium:YAG that Robert Gregg and myself are currently developing.”

Ha! Al,

Very funny……………but, who’s kidding?

How VERY right you are, Al. You guys are designing the next erbium device with all of your experiences and insights. You just don’t know it, yet.

I’ll help you put it together………..:cool:

Bob
Digital Dude

October 17, 2003 at 5:51 pm #9436 Reply

Kenneth Luk
Spectator

Hi Bob,
Make sure you put in the laser meter to ensure correct power output as well on the new millennium Er:Yag :biggrin:
Any discount on getting it and the Periolase? 😉

Ken
P.S. Variable Hz as well please!:smile:

(Edited by Kenneth Luk at 1:54 pm on Oct. 17, 2003)

October 18, 2003 at 12:31 am #9433 Reply

Glenn van As
Spectator

I saw Andrew today and we talked about our findings for the Delight.

My findings were that I was using 9 (NINE ) ml / minute.

Now if I turn it down I might get better ablation but will I get more sensitivity.

What are other people getting from their lasers.

Glenn

October 22, 2003 at 1:22 am #9426 Reply

dkimmel
Spectator

Looks like at 20% water I am at 20ml/min and at 11% water I am at 12ml/min. This was at 60% air. Interesting part is the % air does make a difference. That is 60% air at 20% water was 20ml/min.
40% air at 20% water was 26ml/min.
20% air at 20% water was 32ml/min. (20% air was the min air pressure to obtain a spray)

Clinically I did not change my % air. I stayed at 60% air. At the 20% water I had a good albation rate and no sensitivity. When I dropped the water down to 11% the rate of albation decreased. I also noticed a consistant sparking on the enamel. At at close to 20% water the sparking disappeared unless I approached a pigmented area.
Glenn at 9ml/min do you even need to suction?
David

October 22, 2003 at 11:43 pm #9424 Reply

Anonymous
Guest

QUOTE

Quote: from Swpmn on 11:21 pm on Oct. 16, 2003
Dave:

With the Waterlase, at 2.75 W and my low 11% water setting, I’m not seeing char but I’m using a much more defocused ablation technique at 1.5mm like Colonna showed us in Atlantic City. Still have lots of irrigation on ablation site even at 11% setting.

Al

Al,

Thanks for this post! Today we adjusted down to 50/20 2.5 W and it seemed like on pedo teeth we could go right at it w/ no numbing time – and since we had about 6 kids this afternoon I’m doubting it was just a streak of exceptionally relaxed,nonfeeling kids . Also, today an occlusal on a lower second molar- redhead teenage girl , at 5.25W 50/20 defocused and not even a blink. It was awesome!
I think tomorrow we’ll drop the air about 10 and the water another 4-5 and try that out.

Thanks again,

October 23, 2003 at 1:57 am #9440 Reply

Swpmn
Spectator

Ron:

That’s great!!! Seems to be working for me.

Al

December 31, 2003 at 4:30 am #9429 Reply

lagunabb
Spectator

Glenn,

From your post on dental town:

“A recent study said that the optimal ml/min was in fact around 2 ml /min for ablation but I find that the sensitivity increase at these lower levels. “

Interesting — Can you please provide the reference? Thanks.

By the way: A long long time ago, I had to testify in an arbitration where the volume of chemical additive to samples was critical to an issue. I had to do bench top measurements to see how to relate droplets sizes to milliters. For a typical dropper (about the size of an eye dropper), one milliliter is about 20 drops so 2 mil/min would be not much more than a wetting film.

December 31, 2003 at 1:43 pm #9430 Reply

Glenn van As
Spectator

Ray as I do this chapter in Dental Clinics of North America I can only rely on the currently available published literature on the subject.

It will not contain HK in the chapter.

PERIOD

Glenn
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