Hi There

My personal thought is that we probably overuse chemical anaesthesia in traditional dentistry. I suspect there are a lot of procedures we could probably do without anaesthetic, but our patients and ourselves are conditioned to use it. When we get the laser out, it is something they have never seen before and don’t necessarily associate in their minds with pain, and as a result may not feel pain. Sometimes they don’t feel anything, and that is good. Sometimes they feel something but don’t necessarily call it pain. I think this accounts for some of the analgesic effect. Some people will feel something regardless of what you do. These are the “failures” in laser analgesia and probably the same people who you end up giving 4 carpules of anaesthetic to do a simple occlusal on.

I have tried laser analgesia a few times, but to be honest I just don’t have the patience to do it routinely. I have had mixed results. My standard technique is to start about a centimeter away and just slowly close in on the tooth at a moderate energy level. This probably takes 10 seconds. I work away for awhile (read until I get bored) and increase the energy in small increments until I either finish the prep, get into dentin or the patient feels it.

I will be getting a scope in the near future, so it will be interesting to see if that makes a difference.

I think the major problem we have is that all patients experience pain differently. If they would just go through some standardization training it would make things much simpler……

Ron, I think a great deal of the success or failure is due to the patients anticipation and perception.  The success rate definitely can definitely be driven higher when the patient is preconditioned with the words -‘ we can always give you a shot, if we need to’ or ‘this is going to feel cold like eating ice cream’. I cringe when I hear the ‘shot’ technique being used, who wants a shot?
Now that being said, I do think that a patient often feels a difference in the procedure, especiallly when moving from a high energy analgesia technique to a prepping energy that is much lower. Again, this may be a way of preconditioning a patient by having them experience a certain level of percussion and energy, followed by a lesser level of percussion and energy, which in comparrison to the high levels, doesn’t seem too bad. Can’t say I ever had any success using the low energy/ slow analgesia technique.

I also agree with your statement about visualization. Since the scope I have pretty much abandoned either the high energy or the slow analgesia techniques and see no difference in my success rate. If you can visualize where the tissue and energy interact, you can control the amount of thermal change and keep many people comfortable during the procedure.    

As far as why some people react differently than others I wonder if the NTI guys aren’t on to something regarding the clenchers/ change of local pH ideas. Maybe the same thing is happening with the areas that respond somewhat hyperactively to the laser. Change in local pH affecting the speed of chemical Rx in the pain response.

Just my totally subjective , unscientific, anecdotal, two cents 😉

p.s. Bruce, if we’re going to standardize patients I’ve got a list of other attributes we should have them work on

I can’t explain “why” it works when it does…but I do know that more than half the time it does work. I also know that just because it fails on one tooth…it does not mean it won’t work on a different tooth in the same mouth. I’ve seen it happen many times. Why would it work with #19, but fail on #20? They’re side by side. A LOT of it has to do with how we remove the amalgams. The pulpal floor is the most sensitive…so I leave it till the very end. I especially want to remove all the amalgam around the edges early on. After I’ve got nothing but a VERY thin layer of amalgam left across the pulpal floor I’ll penetrate it (barely) to gauge their response. If they don’t flinch I’ll continue on. If they do flinch…I’ll try to flake it out with an explorer. You’d be surprised how many cases you thought were gonna fail that you can succeed with by doing this. You can usually flake out very thin amalgam with not much trouble.

All in all I’d say we get it done in a fairly comfortable fashion 75% of the time.

Dan

OK, hot off the press …

Just had a teenager on whom I restored #2-O and #9MF using the Er:YAG with no anesthetic. I started on #2 and, after about 20 seconds of defocused 15Hz/400mJ treatment, dialed it down and went to town. He did OK.

However, for #9, I dialed it down further to 15Hz/150mJ and had only begun when he raised his hand. So, cranked it back up to 400mJ, defocused, treated for 90 seconds and resumed at 15Hz/150mJ. He felt little or nothing. I gave him no suggestions about what to expect.

So, there’s another anecdote to throw into the stack of stuff, for what it’s worth.

— Don

Mark, help me out here …

I’ve heard conflicting reports about the frequency — 15Hz/30Hz advocated as being most effective with C-fibers and Dr. Chen who adamantly insisted that 20Hz is the magic frequency.

Why 10Hz? Just curious …

Ron K:

When we speak of “Laser Analgesia” let me suggest that we make sure to qualify that on this thread we are referring to erbium wavelengths in the 2780-2940nm range. There could be something to laser analgesia with other wavelengths and I’m thinking of the pulsed Nd:YAG. Just my opinion, but to me it never made much physics sense that a wavelength which will be immediately absorbed on the tooth surface could provide any sort of analgesia to the pulp.

Getting that out of the way, I personally had poor clinical success with erbium laser pre-treatment analgesia. Like you say it began to appear that my success rate was similar whether or not I used the pre-operative, defocused bathing with the erbium. My clinical findings seemed to support what I had been taught from laser physics.

So, I began to experiment with different energy/Hz setttings and found that with my 2940nm erbium, 10Hz rep rate with 175-225 mJoules energy seemed to give good success. Under magnification, the setting ablated efficiently and by learning to keep the focal point moving across the treatment site, patients appeared to feel little or nothing. Combining this with careful selection of patient, tooth and lesion has allowed me to finally achieve a 90% success rate on the patients and teeth which I CHOOSE to treat in this manner. Now I’m not saying I have a 90% success rate with all patients requiring composite restorations. Many times I combine chemical anesthesia with erbium laser preparation and my patients greatly appreciate reduction in use of the high speed/slow speed handpiece.

Al

Just an update…..for what it’s worth. Since my last post on this thread (Nov 14)…we’re batting a thousand with “laser analgesia” for removing old amalgams. Haven’t had to grab the syringe for several weeks now.

Dan