Hi all,

Just like to complicate things even more.

I’ve been looking into another Er laser ( Fidelis ) made by Fotona. ( Info can be found in Manni’s Dental Applications of Advanced Lasers.)
Laser delivery: 7 mirror articulated arm
Pulse rate: 2-50 Hz
Pulse duration: 100,300,600,1000 usec

The following is what the rep said about their VSP: variable square pulse.

Our laser is the only hard tissue laser on the market with an adjustable pulse width. The pulse width of the Waterlase is set at 170us. With the Opusduo and the Kavo Key 3 the pulse width changes but you have no control over the changes, the laser does it automatically depending on which setting you select. And importantly the shortest pulse width of either of these units is 200us. I suspect the DELight is much the same as the Opus Duo and the Key3. Our laser has four different pulse width settings which you can choose manually. The shortest available is 80us which is more than half as long as its closest rival. This allows the user to get a very short pulse of high peak power which gives very efficient cutting of enamel without requiring a large amount of energy per pulse to gain effective cutting. So you not only get fast enamel cutting (the fastest) but you also get the selective removal of caries that is only possible with an Erbium:YAG. (as opposed to the Er Cr YSGG of the Waterlase). This is the key point that makes our hard tissue laser very well suited to laser cavity preparation.

Sounds good but the articulated arm doesn’t look too user friendly!
Any comments?

Ken

(Edited by Kenneth Luk at 8:50 pm on Sep. 22, 2003)

Kenneth:

Very excellent post.

First, Niemz clearly brings out, that with Erbium energy, until you get below 1 microsecond in pulse-width, you are dealing with thermal-mechanical ablation of dental tissues. So as far as the ablation mechanism is concerned, 80 microseconds is thermal, as is 200 as is 400.

The area to look out for (in my opinion) is the Hz. At smaller pulse widths, and higher Hz (up tp 50Hz as you said in your post) you need to worry about pulse-stacking and heat build up.

My opinion would be, that as long as you keep enough water on the ablation site during irradiation (heat sink) you may be OK.

I would like to see a reliable study that would say something like:

“80 microsecond pulse-widths at 40Hz cuts faster with no apparent thermal consequence than 200 microsecond pulse-widths at 20Hz”

If Fotona could produce such data, in the face of the available literature stating that excess heat will inhibit ablation, I would like to see it.

With such data, I would take a serious look at thier claims. Without it, I would be very careful with these energies, at these pulse widths, pumping up the Hz to 40 or 50Hz, especially in Bone.

I am interested in other opinions please.

Eric Bornstein DMD

Ken:

Thank you for the kind words.

You are correct in your assumptions, as long as you understand the energies (and I believe yo do).

If however a dentist buys this FOTONA Er:YAG, and say does the following, by only listening to a salesman:

1) Turns up the watts to high
2) Turns the pulse-width down to 80 microseconds
3) Turns up the Hz to 50 (in effect double the energy from 25Hz)

Then you have maximal power output (probably faster cut), with a phenomenon known as pulse-stacking, that may make the extra 60 or 70 micrseconds of thermal relaxation time in the pulse-width irrelevent if the heat goes up significantly at the ablation site, for a variety of reasons already discussed on the DT board.

I would love to see some hard data describing the lower pulse width with higher Hz and power output, to see exactly how and if the heat is a problem.

Nice post

Eric Bornstein DMD

Ken,
Was there any research to support those statements about the lasers or was that opinion? I would love to see the literature that supports those statements.
Al B

Hi Eric,

I’ve just received the document on VSP. Not had a chance to read it but want to post it for your comments first.

The protocals for using VSP is as follows:

VSP 100us ; short pulse 300us ; long pulse 600us ; very long pulse 1000us

Enamel – Very Short Pulse 400mj and 10hz
Dentine – Short Pulse 300mj and 10hz
Caries – Short Pulse 120 – 220mj and 10 -15hz
Bone – Very Short Pulse 200 – 400mj and 10hz
Soft Tissue – Long Pulse 100-200mj and 15 – 20hz

The enamel cutting setting is Very Short Pulse at 4 watts. This in only 40% of the lasers potential power output (which is 10 watts) but we don’t use more than four watts because it as fast as you would want or need to use the laser for cavity preparation instead of a drill.
_____________________________________________
VSP Doc.

In vitro study of intrapulpar temperature change with
short and very short pulse Er:YAG laser preparation of class V cavities

Brugnera Junior, A.1; Zanin, F.1; Marchesan, M.A.2; Silva, R.S.2; Pécora, J.D.2.
1Laser Center – Camilo Castelo Branco Uníversity; APCD and Federal University of Rio de
Janeiro -UFRJ – Brasil.
2Dental School of Ribeirão Preto, University of São Paulo – Brasil.

High-density lasers such as CO2 and Nd:YAG generate heat in tissues. This is a concern for researchers because this heat which is generated during cavity preparation can cause irreversible changes in the dental pulp as well as periodontal necrosis (Zack and Cohen, 1965).
Er:YAG laser, because of its interaction with water, causes dental tissue ablation without causing injuries such as fusion, cracks and carbonization (Keller and Hibst, 1995; Watanabe, 1998). Thus, the Er:YAG laser has been indicated for the removal of caries, cavity preparation and preparation and disinfection of root canals.
Various studies have recommended parameters for the use of Er:YAG laser for the treatment of caries of the enamel and dentin without studying the different increases in temperature caused by the laser in the individual teeth, which because they have different anatomic characteristics, present different thermal diffusion responses.
The authors studied the intrapulpar temperature change in 10 incisors, 10 canines, 10 pre-molars and 10 molars during Class V cavity preparation with short pulse (250 ms/pulse) and very short pulse (80-120 ms/pulse) Er:YAG laser, using the following parameters: 10 Hz frequency, 500 mJ potency, 6 s, 10 mm distance, 25 m1/min water flow, at 230C and 65% humidity.

The greatest increase in temperature was found in the incisors and the least increase in the molars at both pulse modes. The very short pulse mode caused less of an increase in temperature in the pulp chamber in all teeth than the short pulse mode.

_____________________________________________

In Vitro Study of Cutting Efficacy of Very Short Pulse (VSP)
and Short Pulse (SP) Er:YAG laser cavity preparation
Brugnera Junior, A.1; Marchesan, M.A.2; Silva, R.S.2; Zanin, F.1; Guerisoli, D.M.Z.2,
Pécora, J.D .2.
1 Federal University of Rio de Janeiro —UFRJ – Brasil, and
Laser Center – Camilo Castelo Branco University.
2 Dental School of Ribeirão Preto, University of São Paulo – Brasil.
A new pulse for Er:YAG laser (very short pulse, VSP: 80-120 ms/pulse) has been developed for faster cutting with less thermal damage. This study evaluated, in vitro, the cutting efficacy of VSP and SP (250 ms/pulse) Er:YAG laser cavity preparation. A total of 20 hemisections of molar crowns were placed in an incubator at 37ºC and weighed on a precision scale (MLW, Germany). After the 3rd measurement the weight stabilized and this weight was used as the initial sample value. A cavity was made in each sample using Er:YAG laser (Fidelis model 32OA, Fotona Medical Lasers, Slovenia) at both VSP and SP. The parameters used were: 10 Hz frequency, 500 mJ potency, 6 s, 10 mm distance, 25 ml/min water flow, at 23ºC and 65% humidity. The teeth were then dried with absorbent paper and placed in the incubator at 37ºC. The teeth were weighed and after stabilization of weight the difference in mass was calculated. The results showed that VSP Er:YAG laser was more efficient for cavity preparation than SPEr:YAG laser.

_____________________________________________

Er:YAG Laser Cavity Preparation with Variable Pulsewidth:
A Microleakage Study.
R.S. Navarrol; S.C.Gouw-Soares1; P. Haypek1; D.M. Zezell2; M.N. Youssef1, C.P. Eduardo1.
1Faculdade de Odontologia-FOUSP; 2Centro de Lasers e Aplicações-IPEN/CNEN-SP,
São Paulo- Brazil
The Er:YAG laser (2.94,mm) is highly absorbed in both water and hydroxyapatite has great applicability on cavity preparation. The purpose of this study was to evaluated in vitro the microleakage in composite restorations performed by Er:YAG laser. Identical size class V cavities were prepared at the buccal surfaces in twenty-five bovine teeth by Er:YAG laser (Fidelis 320A, Fotona, Slovenija) with irradiation parameters 350mJ/ 4Hz or 400mJ/ 2Hz and pulse width: group 1: VSP- Very Short Pulse; group 2: SP- Short Pulse; group 3: LP- Long Pulse; group 4: VLP- Very Long Pulse and group 5: by high-speed drill (control group). All cavities were etched with 35% phosphoric acid for 15sec, washed with water, treated with adhesive system (Single Bond-3M), filled with composite resin (Z-250-3M). The specimens were stored at 37ºC in distillated water and polished 24 hours later with Sof-Lex discs (3M) and thermally stressed (700 cycles/ 5(-55ºC). The teeth were impermeabilized, immersed in 50% silver nitrate solution for 8 hours, embedded in acrylic resin and sectioned longitudinally with Isomet saw and exposed to Photoflood light (G.E.) for 10 min to reveal the stain. The specimens leakage were observed under stereomicroscope, SEM, and were double blind evaluated with scores (0-3), by 3 different examiners. The results were analyzed with Kruskal-Wallis test (p(0.05), showing no significant differences between tested groups. The morphology of cavities performed by laser showed irregular cavosurface enamel and internal walls, with more conservative pattern than conventional cavities. The laser irradiation parameters and pulse width used in this study for cavity preparation with Er:YAG have no influence on microleakage.
Financial Support: CNPq; CAPES

_____________________________________________

Regards,

Ken

(Edited by Kenneth Luk at 7:35 am on Sep. 24, 2003)

If anyone is interested here is their web address
http://www.fotona.si/lasers/dentin.html

Ken:

I e-mailed Fotona to see where they are in the FDA process for my own info. I have yet to hear from them.

When they get back to me I will let you know.

Eric Bornstein DMD

Hi Ken

No, I am pretty much sold on the DeLight at this point. Mainly based on the research I have done on here and talking to some laser owners. I have the DeLight rep coming by for lunch in about 15 minutes and the Biolase rep coming by tomorrow for lunch. No one from Font has offerd to buy me lunch yet

Don’t know enough about the history of Fotona with North American customers, support, training etc so it is not high on my list at this point.

Looks like leasing is ready to go so its just a matter of signing on the dotted line. Nervous but excited.