How Cold Lasers Work…

“Cold Lasers” seem to be the latest Buzz Word in Laser Dentistry. Cold Lasers are also known as “Soft Lasers” or, more scientifically, Biostimulatory Lasers.  As already mentioned in previous posts, these lasers do not cut or vaporise any tissue.  Although often very powerful, these lasers are defocused enough so that the tissue interaction is that of biostimulation and not thermal.

As we have seen earlier, cold lasers can be used for a variety of applications not only in dentistry, but also in medicine.  Their typical application field is that of tissue healing (Well, lately the application of hair re-growth has also been added and actually FDA approved, but there is little if any scientific substantiation to this at this point).

In order for laser light to be absorbed, there must be receptors.  Such receptors are well known in plants, but there are human light receptors other than those in the eyes and the skin.  In fact, to date more than three hundred photochemically reactive proteins, capable of harvesting low light energy, have been identified in both prokaryotic and eukaryotic organisms.  In humans, the most commonly known photochemically active receptor proteins are the rod and cone pigments in the eye.  However, other human photoreceptors have been discovered in recent times.  In fact today, we know that the majority of our cells have photoreactive molecules in them and we call those CHROMOPHORES.

It has been observed that if laser light is administered in the right dose, certain cell functions are being stimulated, and this is particularly evident if the cell in question has an impaired function.  It is known that laser light will cause certain chromophores in our cells to allow the build-up of radical oxygen species (singlet oxygen, instead of O2), which in turn influences the the formation of ATP (Adenosine Tri-Phosphate), which is the cells basic energy and fuel molecule.  Now, if the production of ATP reaches a certain level within cells, this will lead to a host of secondary effects, which have been studied and measured in several contexts:

  • increased cell metabolism and collagen synthesis in fibroblasts
  • increased DNA and RNA formation in the cell nucleus
  • increased cell division cycles
  • increased cell differentiation cycles of primitive cells (stem-type cells)

All of the above cellular effects will translate into faster healing by virtue of an increased population of cells which are involved in the inflammatory and healing cascades of the body.  Bone and soft tissue tend to heal faster and better after surgery, nerve cells can regenerate themselves at higher rates and pain is often reduced due to a laser-induced block of the pain receptor cells.

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A 100 Watt Laser – And My Doctor Says It Won’t Hurt?!?!

It is an unfortunate business practice, but the sale of medical lasers is largely being promoted by their hardware profile: “X” number of watts, “Y” number of pulses at “Z” nanometers etc.  What is unfortunate about this is that it does not really paint a good picture on what the clinical qualities of a laser really are, because this type of advertising does not really address what kind of “tissue interaction” it produces.  This however is ultimately the most important quality of any laser.  I’ll explain…

First and foremost, the power of the laser (usually displayed in Watts) is the true output power in terms of light energy emitted.  This is in direct contrast to a light bulb for instance.  A 60-Watt light bulb will draw 60 Watts of power out of the socket, but only deliver a fraction thereof as light energy, because most of the power drawn gets converted to heat energy.  In a laser the power rating is NOT what it draws out of the electric socket, but rather the light energy it produces.

Another concept that needs to be addressed is that this power claim describing a laser, can often be misleading.  More often than not, a “high-powered” healthcare laser in the 20 – 100 Watt range achieves this kind or output power mostly in a “pulsed” mode.  This means that the laser will be “on” and “off” several hundred or even several thousand times a second and every time it is “on” it emits 100 Watts.  Since this is a pulse train of laser light, it is important to note that the AVERAGE power may only be in the milliwatt range, so there is effectively only less than 1 Watt being absorbed by the tissues.

The last and most important concept which needs to be addressed is that of the power density at the output tip (aka “fluence”).  A 50-Watt laser with an output diameter of 1 cm will have an entirely different effect on tissues than a 6-Watt laser with an output diameter of only a few hundred microns.  The former will have a biostimulatory effect, whereas the latter will be able to cut tissue.

So, as we can see, the advertising profiles of lasers do not really always reflect the clinical relevance.  It is my opinion that this needs to change eventually, so that the tissue interaction is placed into the foreground and not the hardware profile.


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So what can surgical lasers be used for in dentistry?

Surgical lasers are currently undergoing a tremendous evolution in dentistry.  Much of it has to do with the ability of manufacturers to scale their size down dramatically, and to make them more user friendly.  Additionally, new wavelength are constantly being added to the repertoire, which in turn broadens the

A periodontal procedure performed by a laser

A periodontal procedure performed by a laser

application field.  Dental or surgical lasers are defined by their lasing medium (the substance inside the laser, which creates the laser light), which in turn defines the wavelength of the emitted laser beam.

The following are the most common lasers used in dentistry:

  • Nd:YAG laser
  • Diode laser
  • ER:YAG laser & Er,Cr:YSGG laser
  • Carbon Dioxide laser

Each laser has its own unique application, based on the type of tissue interaction it offers.  Some lasers have their greatest energy absorption in soft tissue, others in bone tissue and yet others in hemoglobin or melanin.  the applications for lasers is basically chosen by their absorption spectrum in human tissue.

One of the main applications today in dentistry is soft tissue surgery.  Lasers are often used in periodontal disease cases, to complement traditional scaling and rootplaning procedures.  Lasers do not cause the kind of discomfort that traditional periodontal procedures cause.  That being said, not all periodontal procedures can be replaced by lasers either.

Another application which is gaining ground is photosterilization of compromised teeth or dental implants.

Photosterilization of a compromized dental implant

Photosterilization of a compromised dental implant

Often times we try to save compromised teeth and dental implants with a grafting procedure, however, a pre-requisite is that the surface of such a tooth or implant is meticulously cleaned and sterilized, or new bone will not form against it.

Laser bone surgery is just in its infancy in dentistry, but new powerful lasers make this possible already.  The advantage of laser bone surgery (in contrast to rotary instruments or piezo-electric instruments) is the cleaner and more sterile surgical field as well as the reduced post-operative inflammation and discomfort.

Lastly there is the new field of biostimualtion, which has actually nothing to do with surgery, but can help dramatically in the healing process.  Biostimualtion was already discussed in a previous post underCold Lasers.

For more information on lasers in dentistry, please visit my website at: http://www.robertgougaloff.com.

So what’s up with these new Cold Lasers?

Cold Laser Application for TMJ Pain

Cold Laser Application for TMJ Pain

This is a post in response to a request I have received and some of the blog posts I have read on other sites.  I hope it is informative for you.  As always I welcome any kind of comments or questions.

First of all, “Cold Lasers” are not to be confused with “Cool Lasers”.  “Cool Lasers” are utilized in cosmetic medicine or dermatology to reduce acne scars or wrinkles.  “Cool Lasers” actually generate enough energy so that the water in your skin cells absorbs the laser light. The absorption in turn causes the instantaneous vaporization or destruction of the cell.  There is really nothing “cool” about this laser, in fact this is a thermal tissue reaction, however, the skin is kept “cool” via external cooling mechanisms.

“Cold Lasers” on the other hand are truly “cold” to the touch and their function is purely geared towards biostimulation and healing.  Nowadays, these lasers are often being referred to as “Biostimulatory Lasers”.  Cold Lasers do not create any heat, yet they are very powerful.  To give you an example, surgical lasers for dental surgery generally range between 2 Watts and 7 Watts in output power.  Cold Lasers on the other hand, can have actually 100 Watts or more output power at their tip, yet they will never cut tissue.  So what’s going on here you ask?!?

Well, the difference is the POWER DENSITY at their delivery end.  Surgical lasers have an emitter tip of a few hundred microns in diameter.  Therefore, a few watts of output power are concentrated into a very small diameter at the cutting tip, which yields a very high power density.  A high power density can have enough

Cold Laser Application for Rapid Orthodontics (Invis

Cold Laser Application for Rapid Orthodontics (Invisalign)

 energy to cut tissue.  Cold Lasers on the other hand have an emitter tip of several millimeters to centimeters in diameter.  So, despite their high output power, the power density at the delivery tip is very small and is therefore incapable of creating a thermal effect in tissues, let alone cut them.  In addition, Cold Lasers often “pulse” (they switch on and off) at very high frequencies.  Their power is usually given for the peak output at each of the pulses, so that the average power output is dramatically lower.

So what do Cold Lasers do for you?  Well, in the simplest sense they transfer photon energy into your cells.  Cells use this photon energy to produce their own energy source, which is a molecule called ATP.  Once cells load up on ATP, they have enough energy to regenerate themselves faster and better.  Research has also shown that Cold Laser therapy can reduce inflammation, by blocking the production of certain inflammatory molecules such as interleukins.

Cold Lasers present a growing treatment modality tool in Laser Dentistry.  Their advantage is that there is no danger of over-dosing, there are no adverse effects, and there is above all NO PAIN involved in the procedure.  New uses for Cold Lasers evolve constantly, but we use them currently in the dental field for improved healing after oral surgery procedures, periodontal surgery, faster implant integration for dental implants, TMJ pain, faster orthodontic movement of teeth and desensitization of teeth.