Dr. Michael Miyasaki - June 21 2021
Understanding Lasers Helps You Get the Most Benefits From Them
Lasers help us do better dentistry, and, in my experience makes my life easier and improves the experience of my patients during their treatment. If I need to place a medicament in a sulcus, gain hemostasis, remove tissue or disinfect a tooth I prefer to use my soft tissue diode laser. Let me share from my experience using dental lasers (soft tissue, all tissue and curing) for over 25 years focusing on the soft tissue diode lasers and how they function so you understand how they work and how they can work for you.
Light Is Different Than Steel Or Electrosurgery
Soft tissue diode lasers work by emitting photons or light at a particular wavelength typically falling between 810-980 nm. This light energy must be absorbed by what we call chromophores to have any affect. Because it is light it can also reflect off a surface, travel through a material or be scattered and have no effect. Therefore, a laser is not comparable to a scalpel or an electrosurgery unit which will cut or ablate everything in their way. Comparing laser energy to bees, the bees will pass by you standing by the flower because they want to interact with the flower.
What’s your Wavelength?
So what absorbs the laser’s energy? Well, that depends on the wavelength, but in general the energy from an 810 nm wavelength laser is absorbed by melanin or hemoglobin. A laser with a wavelength of 980 nm is absorbed more by water. Clinically I have used both 810 and 980 nm wavelength lasers and have found it difficult to differentiate the effects. It reminds me of drinking wine, sometimes it is hard to taste the difference because it is subtle. In an area with bleeding tissue, it may be better to use the laser emitting the energy at the 810 nm wavelength which will best react with the hemoglobin to cauterize the broken capillaries and stop the bleeding. For a periodontal procedure in a wet sulcus, it might be a benefit to use a laser whose energy is best absorbed by water which would be the 980 nm wavelength. But don’t get too caught up in wavelengths, I think the points being brought up next are even more important.
To Initiate Or Not To Initiate
The laser energy is created and passes along a fiber. If the fiber is initiated, meaning some sort of pigmentation is put on the end of the fiber, most of the light energy will be absorbed and converted to photothermal energy at the fiber’s tip. This photothermal energy can be used to ablate tissue or cauterize in a very controlled manner which will minimize tissue trauma. If we leave the fiber’s tip clean the light energy will pass through the fiber, and its end will just be used to aim the laser’s energy, much like we see when using a flashlight. The light from the flashlight goes beyond its end.
Like most general dentists, crowns are a big part of our monthly production and our quality must be constant and predictable. Lasers have become a big part of that. Most lasers use a tip that is between 300-400 microns. By utilizing a laser for troughing crown margins we have eliminated the use of retraction cord. When the preparation is completed the laser tip is introduced into the sulcus and traced around the margin. This creates a 300-400 micron “gap” that allows our iTero scanner to receive a clear view of the margin.
Continuous or Pulsed Delivery
We can deliver the laser energy in basically two different ways. One called continuous is when, again like a flashlight, we turn it on and get a constant beam of light emitted. The other way is called pulsed which would be like turning the flashlight on and off with millisecond gaps. You can also think of it like a light house light spinning and you see quick flashes of the light and then you must wait. This waiting period is when the laser energy is off and allows the tissue to cool and we call this thermal relaxation. When used in the pulsed mode there is typically less energy delivered to the tissue over time. If we have two lasers set to emit the same power, for example 2 Watts, the one set to the continuous mode is putting out 2 Watts of power continuously. A common pulsed setting has the laser on 50% of the time and off 50% of the time so if it is set at 2 Watts of power this laser is only putting out 1 Watt of total power over the same time because it is off 50% of the time. You may need to go back and look at the math, but the takeaway is we can control the power in many ways.
Don’t Get On A Power Trip
So taking all the above into account I have learned to begin at a lower power and titrate the power up until I achieve the desired effect. If I have not anesthetized the patient, I may do a gingivectomy at a lower power. If I am doing a frenectomy through less effused, fibrous tissue I may use a higher power. It quickly happens that soon after using a laser you will find a sweet spot setting for most of your procedures. My rule is to use the lowest power possible to increase the comfort for my patients and to achieve a more predictable outcome because we have minimized any trauma.
Walk To The Light
So taking all the above into account I have learned to begin at a lower power and titrate the power up until I achieve the desired effect. If I have not anesthetized the patient, I may do a gingivectomy at a lower power. If I am doing a frenectomy through less effused, fibrous tissue I may use a higher power. It quickly happens that soon after using a laser you will find a sweet spot setting for most of your procedures. My rule is to use the lowest power possible to increase the comfort for my patients and to achieve a more predictable outcome because we have minimized any trauma.