Evidence-based research that has yielded positive results with Photobiomodulation has been conducted utilizing Class 3b laser or LED equipment vs Class 4 systems. Class 4 systems over-irradiate tissues, creating excessive heating and thereby inhibiting cellular healing.
The mechanisms of Photobiomodulation work due to photochemical reactions in our cells, not by heating the cells. The definition of a Class 3b laser is power densities at 500 mW or less. Class 3b systems are non-thermal and do not produce heat, just photochemical reactions. Class 4 laser therapy systems range from 501 mW all the way up to 50,000 mW which produces heat in the cells. Therefore, Class 4 laser treatments do NOT result in Photobiomodulation, even though they claim to do so. They even post research on their websites in an attempt to convince people that laser therapy with their equipment works, but any research that yields positive results is more than likely using 1,000 mW or less.
Here is a research article that was actually posted on a leading brand of Class 4 laser therapy’s website last year: https://onpointneuro.com/wp-content/uploads/2018/07/2-In-vitro-and-in-vivo-optimization-of-infrared-laser-treatment-for-injured-peripheral-nerves.pdf
It basically states that treatments to a peripheral nerve with 1-Watt (1,000 mW) of power yielded a regenerative effect in the nerve. But treatments with a 4-Watt (4,000 mW) laser INHIBITED peripheral nerve regeneration.
Unfortunately, many of the lasers found in the United States at chiropractic and physical therapy clinics or even physicians’ offices seem to be the high-powered Class 4 Lasers. Why is this?
It may be because it is much easier to sell a Class 4 system because higher power densities result in an immediate analgesic effect. They decrease pain right away. Most providers such as physical therapists or chiropractors have some type of pain themselves. So, a 5–8-minute treatment seems miraculous. And these companies actually lie to providers as well as to patients, telling them that “Higher Power is Better” with “Shorter Treatment Times and Fewer Treatments Required.” But the exact opposite is true. Photobiomodulation works, but only with LOW POWER and LONGER DURATIONS.
Examples of Class 3B lasers or light therapy systems are The Bioflex (which is what we primarily utilize at Peak LiLT), Microlight, and Thor (which is what NASA uses on the Space Station) and the Vie Light (which we are about to start implementing in new case study research we are embarking on in treating dementia and Parkinson’s Disease with LiLT).
This article provides a good in-depth summary of Class 3B versus Class IV Lasers.