Premolar and molar protocol: Fluency vs. Average Power

[drnewitt]

Hey Zen

I have found that starting with the 400 at 10hz 200+ is great for getting through the enamel but it can still get a little sensitive on some, as you know. I found switching down to 10Hz 170mj seems to eliminate the sensitivity, once I’m through the enamel.

Defiantly need to remove ablation product with etch or mechanical though as the 10hz 170-200 leaves a loose rough surface.

Thanks for the info on Fluency vs. Average Power. How did you do your math?

[zendentist]

Dr. Newitt:

My guess is that the lower average power of the 400um tip to achieve the same fluency might be a key to further lowering sensitivity rates.

As far as the math goes, apparently I don’t have a clue. Like Lynyrd Skynyrd sang (paraphrased) “I know a little ’bout (math), and baby I can guess the rest.” Halfway through my second Corona, I realized that in my intensity of converting millijoules to joules, micrometers to centimeters, and beer in liquid matter, I forgot about that pesky Pi constant. While the relative fluencies still double between when decreasing tip size form 600 to 400 um, the actual fluency values are (I think) 71.4 J/cm2 for the 600 um tip, and 153 J/cm2 for the 400 tip. That answer will probably change tomorrow. ( I thought 500 J/cm2 was rather high).

I think you were politely telling me to check my math; if not, please check mine:

200mj pulse energy = 0.2 Joules

600um = .06 cm; radius = .03cm; Pi x radius2=.0028cm2

0.2J/.0028cm2 = 71.4 Joules/cm2

similarly for the 400um tip, radius = .02cm

Pi x radius2= .0013 cm2

.02J/.0013 cm2= 153 J/cm2

Gotta run over to DT and correct my post there before one of those sharp eyed cutthroats makes further mincemeat of me.

Wes

[N8RV]

You know, Wes, I was following most of your math logic (which should really scare me), but hit a wall with the Pi thing … and the fluency.

So, taking a cue from you, I opened a Corona and mulled it over. About three Coronas later, I suddenly found that it all made sense — I became fluent in several languages and I ate the pie.

You are indeed brilliant!

[JanetCentury]

Thank you all for the 10 Hz advice. Been doing much better on the posterior teeth. Also helps that I have been insisting on setting them up in the room with the microscope. I find I can better anticipate when they will start to feel it and turn the power down ahead of time.

Thanks again!

[Glenn van As]

The microscope helps so much in lower the power settings. I would love to take a survey and get peoples average power settings for different procedures and different tissues and correlate them to loupes.

The SLOP factor which stands for (Super Loss Of Perception) occurs when you dont have enough mag (or any at all) to account for the interplay between tip of the erbium lasers and the tissue. I was pleased to see in the ALD notes that attendees were encouraged to bring their loupes.

We are getting there…………

GRIN

glenn

[zendentist]

QUOTE

Quote: from JanetCentury on 7:30 pm on Mar. 8, 2006
Thank you all for the 10 Hz advice.  Been doing much better on the posterior teeth.  Also helps that I have been insisting on setting them up in the room with the microscope.  I find I can better anticipate when they will start to feel it and turn the power down ahead of time.

Thanks again!

Glad to hear it, Janet. It has really been working well for me, too; sort of standing up to the test of time, as it were.

Wes

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