As the laser precisely cuts or "vaporizes" soft tissue, which is called ablation, it coagulates the tissue. This controlled coagulation increases hemostasis and is almost bloodless in many cases. This hemostatic control combines with the bactericidal effect of the laser energy at the surgical site, reduces the discomfort during treatment, and minimizes the risk of infections and the need for antibiotics and sutures.
It also minimizes the inflammatory response, allowing faster and improved healing with less postoperative discomfort. The benefit of laser use for soft tissue treatment and management is that the treatments are often less invasive, more precise, and very conservative, preserving the healthy tissue while treating the diseased site. These benefits greatly reduce discomfort during treatment and minimize the need for local anesthesia for many procedures.
The ability of laser light energy to ablate (vaporize or cut) tissue is dependent on how well the energy is absorbed by that tissue, the amount of energy or power (watts), and the amount of time the energy is being emitted into the tissue. The key to achieving the maximum efficiency for this tissue interaction is to match these variables with the chromophores (absorbers of light) present in the tissue with a laser that emits the proper wavelength.
The chromophores found in oral soft tissue are water, hemoglobin, oxyhemoglobin, and melanin. With oral soft tissue being comprised of approximately 70% water, it is the primary chromophore that the laser should be targeting. A study by Cecchetti et al., demonstrated that when comparing light energies in the near infrared range, the 980 nm (nanometer) wavelength used by a few diode lasers is absorbed more than 10 times greater than the 810 nm wavelength that is used by most diode lasers.
To compensate for the lack of light energy absorption of the 810 nm class of lasers, the fiber tip is initiated by blocking the light energy with the ink of an articulating paper or the carbon of a cork. This fiber tip essentially becomes a hot glass rod that vaporizes the tissue by conduction heat transferred by direct contact of the fiber with tissue.
The 980 nm class lasers take advantage of the tissue's 70% water content, which allows the high absorption of its radiant light energy into the tissue to significantly enhance the laser's ablating (vaporizing/cutting) efficiency. Additionally, the 980 nm wavelength allows for water irrigation to be used while ablating, enabling convection cooling to the surrounding tissue to control collateral thermal damage.
Also, the fact that the fiber does not need to be initiated enables the absorption of its radiant light energy in the tissue's other chromophores of hemoglobin, oxyhemoglobin, and melanin even though the percentage of these is greatly less than water.
the real benefit of the 980 nm radiant energy absorption and cooling of the surrounding tissue with water irrigation. By having the ability to use either radiant or conductive energy transfer and convection cooling possibly makes the 980 nm class of lasers the ideal wavelength for soft tissue ablation.
Controlling the amount of energy in each pulse of the laser light and the amount of time that it interacts with the tissue also has a significant impact on the laser's efficiency. There is a linear relationship between the energy in a pulse of light energy and its ablation efficiency. Often this is accomplished by managing the length of time the tissue is energized with laser energy relative to the amount of time it is allowed to relax, enabling the surrounding tissue to cool before the next pulse. The more a laser can control its pulse width and emission/duty cycle, the more effective the laser will be in successfully managing the outcome of the remaining surrounding tissue.
Using the high peak power with microsecond pulse features on the simple–to–use but more sophisticated lasers allows specific microscopic tissue to be precisely removed with each pulse. It also allows thermal recovery (thermal relaxation) between each pulse, therefore minimizing any collateral tissue damage and postoperative discomfort.
With a high powered 980 nm diode laser (greater than 6 watts), this precision can be further enhanced by using water irrigation for convention cooling, allowing the clinician to precisely control his or her clinical options and modes of treatment. This is especially important for procedures such as biopsies and sulcular debridement (sometimes referred to as sulcular decontamination).