Interesting thread. Here is my take.

“There was no evidence of any enhanced dental laser ablation, which was proposed by thr hydrokinetic effect proponents when the erbium beam propagated through the aerated mixture of water droplets. Moreover, additional energy out of the laser handpiece is required when using the erbium laser in conjunction with the aerated spray.”

Freidberg et al., Pulsed erbium laser ablation of hard dental tissue: The effects of atomized water spray vs water surface film,Lasers in Dentistry VIII, SPIE Vol. 4610 (2002)

It has very little to do with being able to see the tooth.

If you substantially increase the water spray in front of the beam, You are attenuating the Erbium photons from doing thier job, which is thermal-mechanical ablation with the interstitial water in the enamel.

Eric Bornstein DMD

Quote: from ericbornstein on Sep. 17, 2003
If you substantially increase the water spray in front of the beam, You are attenuating the Erbium photons from doing thier job, which is thermal-mechanical ablation with the interstitial water in the enamel.

Robert ,
I  think that is exactly the point Eric was making. More water in front of the beam, more energy needed to do the same procedure because the water spray absorbs some of the energy.

Its a quick read if you skip the math or greek or whatever that stuff is!

I am fascinated by all of this talk about HK. Before you should even place the title of “theory” on it, the idea must have some feasibility of occurring. Like “the world is flat!” You look out and it looks flat. OK, that’s feasible. Then you get greater understanding and perspective and you “see” as well as understand that the world is round. Hate to break it to you but the world is round!

Now – lets look around us. Were do you see any laser light – or photons that may be generated by lasers (and I will contain this discussion to photons produced by lasers – that is wavelengths greater than or equal to 180 nm but less than or equal to 1 millimeter) causing atoms (or any matter for that matter) to move physically from one point to another? They don’t – it doesn’t happen. Photons are “absorbed” into matter. The matter receiving quanta of energy (photons) greater than it is giving off begins to “vibrate” faster than it was. Matter does not move because the photons moved it. It increases vibration as increased amounts of energy are absorbed. Now if a great deal of energy is absorbed and there is a great deal of matter absorbing that energy (like two or more atoms next to each other) then that rate of vibration causes the atoms to bump into one another and THAT causes them to move – NOT the energy being absorbed – but the effect on the atom and what the atom does AFTER the energy is absorbed – hitting one another – bumping into one another – because of the increased vibration. This is what happens when you boil water on a stove. You put photons – in the form of heat – infrared – into the water and the water turns to steam – observable! Correct? (If you microwave the water the same thing happens – but then that isn’t laser light – and that is beyond our discussion here.)

Now that we have looked at water (liquid) on the stove turning to steam (gas) when we put infrared energy (heat) into it – lets now look at the SAME principle – putting the photons from the Erbium laser (infrared heat) into the water (liquid). When we do that the energy is absorbed into the water faster (greater energy – smaller area) than when we were putting the heat from the stove into the water. We should get the same results – just faster! And that – my friends – is the whole of it. It just isn’t any more difficult than that.

If you increase the water spray, as you are using your Erbium laser, that water is absorbing energy and you will need greater amounts of energy to get through that water to the tooth and cause absorption there. The water that is absorbing the energy between the tooth and the laser tip is simply doing one of two things – it either turns to steam which expands as gas in ALL directions equally from that point of absorption or it turns into HOT WATER – but it does not increase its velocity only vibration. (I realize I have not discussed plasma – which also can occur – but do you really think that is necessary?)

The only mechanism that causes the enamel, or the dentin, or schmutz to be removed from the surface of the tooth is when the Erbium laser energy (photons) is absorbed into the substrate of the tooth – the hydroxyapatite or the water in the tooth – causing these materials to change physical states – from solid to gas or liquid to gas. In so doing they explode (rapid change in the state of matter) off the surface of the tooth because of the quanta of energy being absorbed.

What ever you wish to call the increased vibration of matter, in this case, is your prerogative. But this claim of HK mechanism of action (photons hitting matter) does not cause the increase of velocity of matter from one point to another. No matter how much energy you put into the matter it only increases in vibration.

Food for thought: there is a novelty toy at the gift store – a glass bulb containing four diamond shape pieces of metal – painted black on one side and silver (unpainted) on the other – suspended in a frame from a needle so they may turn inside the glass bulb with a minimum of friction – usually in a rarefied atmosphere. When you place this toy in the sunshine the metal frame inside the bulb begins to turn. By what mechanism does it do so?

Delwin

Mark:

I know from your posts on DT that you would rather take your ball and go home than debate me on the science. But, if you have the time, read from these three studies to see EXACTLY what the water sprayed ON on the ablation site means, and why it is of great importance.

In a review of the use of this laser for middle ear ablation procedures, Frenz et al (1) stated that otological surgeons have identified the advantages of this laser for osseous surgery. These are the water absorption characteristics of the wavelength, and the precise bone ablation with minimal residual thermal energy. The histological data for Er:YAG lasers, when used by otological surgeons to perforate stapes footplate (osseous ear tissue) in surgical procedures, demonstrates that the lateral thermal damage associated with the bony cut was restricted to only 5-10µm beyond the cuts.

When attempting to cut nasal bone with a laser, Truong et al (2) described two specific criteria that should be met before a laser wavelength is chosen. These are rapid tissue ablation and an absence of visible char in the ablation site. They concluded that this laser produced an excellent result, and further stated that the addition of a water spray on the area being irradiated during ablation resulted in the lowest level of char and presumably the lowest thermal damage to the tissue. It was also noted that as long as the surface of the ablated tissue remained moist with a water spray throughout the ablation process, and the laser was used at appropriate settings, char was not seen regardless of the size/volume of the treated tissue. (2)

These results agree with an earlier study by Romano et al (3) using Er:YAG lasers to cut cortical bone. These investigators observed a linear increase of ablation depth with the number of pulses. A greater number of pulses, translates into more ablative energy in the area being irradiated per unit time. It was found that as long as adequate water spray was provided to the area, more bone was ablated with additional pulses (per unit time) without the char formation that would normally be an expected consequence of extra heat from the added pulses. It was also calculated that repetition rates beyond 20Hz would not significantly increase the peripheral thermal damage to the bone. These studies are germane since all commercially available FDA approved Er:YAG dental lasers function from 7 to 30Hz with a continuous water spray option.

1)Frenz, M. et al, Laser Applications in Middle Ear Surgery: Advantages and Possible Side-Effects. Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems XII, SPIE Vol. 4609, 2002

2) Truong, M. et al, Erbium:YAG Laser Contouring of the Nasal Dorsum: A Preliminary Investigation. Lasers in Surgery: Advanced Characterization. Therapeutics, and Systems XI, SPIE Vol. 4244, 2001

3) Romano, V. et al, Bone Microsurgery with IR-Lasers: a comparative study of the thermal action at different wavelengths. SPIE Vol. 2077, 1994

I am interested on your take now about the water, especially since the machine is FDA approved for bone.

Eric Bornstein DMD

I second that Eric, the Hz settings for the Delight are
3, 10, 20, 25, and 30 Hz

Glenn