The question I’ve always had about “laser analgesia” is the one everyone wants to know: how does it work? It shouldn’t be so hard to figure it out based on what we know about erbium laser tissue interactions, and because of that, I can’t figure out how the laser directly influences nerve fibers. This is an infrared laser that is highly absorbed in water and hydroxylapatite; I don’t think that enough energy is transmitted directly to the pulp chamber to directly affect the pulpal tissues – it has to be absorbed in the dentinal tissue. That leaves photoacoustic and photothermal effects on the odontoblastic tubules – is it drying out the tubules, affecting the fluid column and then normal sensitivity process? Is it gate control at the spinal level? The effect is limited in terms of duration in my experience from 2 to 10 minutes.

To me, what we are actually doing when we expose the tooth to diffuse infrared radiation (the fluency at the tooth surface is below the ablative thresholds of the tissues contacted, so how do we expect it to affect the pulp directly?) is heating and drying the tooth. Based on that, my guess is that it causes a gate control phenomenon. Beyond that, it’s all surmise, but logic dictates that it is not as complex an effect as we are making it out to be.