Frequently Asked Questions
Answer: Regarding the therapy, we have chosen to use the term LLLT (Low Level Laser Therapy). This is the dominant term in use today, but there is still a lack of consensus. In the literature LPLT (Low Power Laser Therapy) is also frequently used. Regarding the laser instrument, we have chosen to use the term "therapeutic laser" rather than "low level laser" or "low power laser", since high-level lasers are also used for laser therapy. The term "soft laser" was originally used to differentiate therapeutic lasers from "hard lasers", i.e. surgical lasers. Several different designations then emerged, such as "MID laser" and "medical laser". "Biostimulating laser" is another term, with the disadvantage that one can also give inhibiting doses. The term "bioregulating laser" has thus been proposed. An unsuitable name is "low-energy laser". The energy transferred to tissue is the product of laser output power and treatment time, which is why a "low-energy laser", over a long period of time, can actually emit a large amount of energy. Other suggested names are "low-reactive-level laser", "low-intensity-level laser", "photobiostimulation laser" and "photobiomodulation laser". Thus, it is obvious that the question of nomenclature is far from solved. This is because there is a lack of full agreement internationally, and the names proposed thus far have been rather unwieldy. Feel free to forget them, but remember LLLT until agreement is reached on something else.
Answer: Basicly yes. There are some 100 double-blind positive studies confirming the clinical effect of LLLT. More than 2000 research reports are published. Looking at the limited LLLT dental literature alone (265 studies), more than 90% of these studies do verify the clinical value of laser therapy.
Answer: The book "Low Level Laser Therapy - clinical practice and scientific background" is the best reference guide for literature documentation.
Answer: That is true. But you cannot just take any laser and irradiate for any length of time and using any technique. A closer look at the majority of the negtive studies will reveal serious flaw. Look for link under Laser literature and read some examples. But LLLT will naturally not work on anything. Competent research certainly has failed to demonstrate effect in several indications. However, as with any treatment, it is a matter of dosage, diagnosis, treatment technique and individual reaction. Refer the link critic on critics.
Answer: Examples of lasers which can be used in medicine: Laser name Wavelength Pulsed Use in medicine or cont. Crystalline laser medium: Ruby 694 nm p holograms, tattoo coag. Nd:YAG 1 064 nm p coagulation Ho:YAG 2 130 nm p surgery, root canal Er:YAG 2 940 nm p surgery, dental drill KTP/532 532 nm p/c dermatology Alexandrite 720-800 nm p bone cutting Semiconductor lasers: GaAs 904 nm p biostimulation GaAlAs 780-820-870 nm c biostimulation, surgery InGaAlP 630-685 nm c biostimulation Liquid laser: Dye laser (tuneable) p kidney stones Rhodamine: 560-650 nm c/p PDT, dermatology, Gas lasers: HeNe 633, 3 390 nm c biostimulation Argon 350-514 nm c dermatology, eye CO2 10 600 nm c/p dermatology, surgery Excimer 193, 248, 308 nm p eye, vascular surgery Copper vapour 578 nm c/p dermatology There are many other types, but those mentioned above are the most common.
Answer: Yes and no! Read the following: The following factors are of importance regarding the eye risk of different lasers: The divergence of the light beam. A parallel light beam with a small diameter is by far the most dangerous type of beam. It can enter the pupil, in its entirety, and be focused by the eye's lens to a spot with a diameter of hundredths of a millimetre. The entire light output is concentrated on this small area. With a 10 mW beam, the power density can be up to 12,000 W/cm2 The output power (strength) of the laser. It is fairly obvious that a powerful laser (many watts) is more hazardous to stare into than a weak laser. The wavelength of the light. Within the visible wavelength range, we respond to strong light with a quick blinking reflex. This reduces the exposure time and thereby the light energy which enters the eye.
Light sources which emit invisible radiation, whether an infra-red laser or an infra-red diode, always entail a higher risk than the equivalent source of visible light. Radiation at wavelengths over 1400 nm is absorbed by the eye's lens and is thus rendered safe, provided the power of the beam is not too high. Radiation at wavelengths over 3,000 nm is absorbed by the cornea and is less dangerous. The distribution of the light source. If the light source is concentrated, which is often the case in the context of lasers, an image of the source is projected on the retina as a point, provided it lies within our accommodation range, i.e. the area in which we can see clearly. A widely spread light source is projected onto the retina in a correspondingly wide image, in which the light is spread over a larger area, i.e. with a lower power density as a consequence.
For example: a clear light bulb (which is apprehended as a more concentrated light source) penetrates the eye more than a so-called "pearl" light bulb. A laser system with several light sources placed separately, such as a multiprobe (the probe is the part of the laser you hold and apply to the area to be treated: a single probe means there is only one laser diode in the probe, as opposed to a multiprobe, which has several laser diodes) with several laser diodes, can, seen as a whole, be very powerful but at the same time constitute a smaller hazard to the eye than if the entire power output was from one laser diode, because the diodes' separate placement means that they are reproduced in different places on the retina. We have often heard this kind of remark: "If it's a class 3B laser then it's fine, otherwise it has no effect....". This is of course entirely incorrect and has lead to a situation where manufacturers have produced lasers to meet the 3B classification, so that they will sell in greater volumes.
Let us look at a couple of examples: * A GaAlAs laser with a wavelength of 830 nm, an output of 1 mW and a well collimated beam (1 mrad divergence) is classified as laser class 3B as it is judged to be hazardous to the eye. The reason for this is partly the collimated beam, and partly the wavelength, which is just outside the visible range and hence provokes no blink reflex in strong light. * A HeNe laser with a wavelength of 633 nm, an output of 10 mW and divergent beams (1 rad divergence, which coresponds to a cone of light with a top angle of about 57°) is classified as laser class 3A because, owing to its divergence, it cannot damage the eye. With the recent advent of "high power low power lasers", i.e. GaAlAs lasers in the range 100-500 mW there is another story. These lasers are indeed dangerous for the eye and should only be used by qualified persons and with proper protective measures taken.
Answer: The laser market is very complicated and full of pitfalls. How do you know which instruments are good? What is expensive? Will it be expensive in the long run to buy something cheap? It is easy to make hasty decisions when faced with a skilful salesman - who is likely to know much more about the field than the customer. Before you know it, you've signed on the dotted line. Here are a number of questions which you should ask both the salesman and yourself. You would be well advised to read these carefully in case you regret not doing so later on!
Answer: This applies to GaAs lasers. When a GaAs laser works in a pulsed fashion, the laser light power varies between the peak pulse output power and zero. Then usually the laser's average power output is of importance, especially in terms of dosage calculation. The peak pulse power value is of some relevance for the maximum penetration depth of the light. Some manufacturers specify only the peak pulse output in their technical specifications. "70 watt peak pulse output" naturally seems more impressive than 35 milliwatts average output! Rule of thumb is: Take the "watt peak pulse" figure, divide by 2, and you have the average output in mW.
Answer: There are three main types of laser on the market: HeNe (now being gradually replaced by the InGaAlP laser), GaAs and GaAlAs. They can be installed in separate instruments or combined in the same instrument. * The HeNe laser or InGaAlP laser is used a great deal in dentistry in particular, as it was the first laser available. The HeNe laser has now been used for wound healing for more than 30 years. One advantage is the documented beneficial effect on mucous membrane and skin (the types of problem it is best suited to), and the absence of risk of injury to the eyes. A Japanese researcher has even treated calves with keratoconjunctivitis with excellent results, that is, irradiation of the eye through the eye lid. Because HeNe light is visible, the eye's blink reflex protects it. Normal HeNe output for dental use is 3-10 mW, although apparatus with up to 25 mW is available. An optimal dosage when using a HeNe laser for wound healing is 0.5-1.0 J/cm2 around the edge of the wound, and approximately 0.2 J/cm2 in the open wound. HeNe lasers are used to treat skin wounds, wounds to mucous membrane, herpes simplex, herpes zoster (shingles), gingivitis, pains in skin and mucous membrane, conjunctivitis, neuralgia, etc. It should be noted that HeNe fibres cannot be sterilized in an autoclave. The alternative is to use alcohol to clean the tip, or to cover it with cling-film or a thermometer sleeve. HeNe lasers cost somewhere between US $3,000 and $4,000, depending on their power output and the quality of their fibres. InGaAlP lasers of the same power costs usually about half as much and can be had with considerably higher output. * The GaAs laser is excellent for the treatment of pain and inflammations (even deep-lying ones), and is less suited to the treatment of wounds and mucous membrane. Very low dosages should be administered to mucous membrane! Most GaAs equipment is intended for extraoral use, but there are special lasers adapted for oral use. Prices are usually between US $3,000 and $6,000 for output power between 4 and 20 mW. A GaAs laser needs an integral output meter that shows that there is a beam and its strength in milliwatts - this is necessary because the light this type of laser emits is invisible. Protective glasses for the patient may be appropriate in view of the invisible nature of the light. In older systems the power output of conventional apparatus follows pulsation. This means that a GaAs laser with an average output of 10 mW when pulsing at 10,000 Hz, only produces 1 mW when pulsed at 1,000 Hz, and at 100 Hz only 0.1 mW. If you therefore want to administer treatment at low frequencies around e.g. 20 Hz (for the treatment of pain), the output power is, clinically speaking, unusable. However, there are GaAs lasers with "Power Pulse", which means that the power output is held constant at all pulse frequencies. This would be of interest to a physiotherapist, for example, when one considers that the GaAs laser has the deepest penetration of the common therapeutic lasers. Large doses can be administered to deep-lying tissue over a short period of time.
A GaAs multiprobe can also shorten treatment times for conditions involving larger areas (neck/shoulders). The GaAs laser is, like GaAlAs and InGaAlP lasers, a semicon-ductor laser. A purely practical advantage of this type of laser is that the laser diode is located in the hand-held probe. This means that there is no sensitive fibre-optic light conductor which runs from the laser apparatus to the probe, but just a normal, cheap, robust electric cable. Optimum treatment dosages with GaAs lasers are lower than with HeNe lasers.
The GaAs laser is most effective in the treatment of pain, inflammations and functional disorders in muscles, tendons and joints (e.g. epicondylitis, tendonitis and myofacial pain, gonarthrosis, etc.), and for deep-lying disorders in general. As mentioned above, GaAs is not thought to be as effective on wounds and other superficial problems as the HeNe laser (InGaAlP laser) and GaAlAs laser. GaAs can, nevertheless, be used successfully on wounds in combination with HeNe or InGaAlP, but the dosages should be very low - under 0.1 J/cm2. * The GaAlAs laser has become increasingly popular during the 1990s. As it is very easy to run electrically, small rechargeable lasers have been put on the market which are not much larger than an electrical toothbrush. (They can run on normal or rechargeable batteries.). 20-30 mW laser diodes are now relatively cheap and the GaAlAs laser gives "a lot of milliwatts for the money". Recently, GaAlAs lasers have appeared on the market with an impressive output of over 400 mW. Many GaAlAs lasers have well-designed, exchangeable, sterilizeable intraoral probes. Output meters are essential because the light from this type of laser is largely invisible.
The price tag for a GaAlAs laser of around 30 mW can be between US $3,000 and $4,000, excluding value added tax. Price differences depend on factors such as output, ergonomics, and standard of hygiene, to name but a few. GaAlAs lasers of 300-500 mW are in the range $4.000-$6.000.
Answer: Yes.Therapeutic laser treatment with carbon dioxide lasers have become more and more popular. This does not require instruments expressly designed for that purpose. Practically any carbon dioxide laser can be used as long as the beam can be spread out over an appropriate area, and that the power can be regulated to avoid burning. This can always be achieved with an additional lens of germanium or zinc selenide, if it cannot be done with the standard accessories accompanying the apparatus. There are small, portable CO2 lasers on the market today - even battery-driven ones - producing up to 15 watts, which is more than enough power output! Prices in the range of $ 10,000 - $25,000. It is interesting to note that the CO2 wavelength cannot penetrate tissue but for a fraction of a mm (unless focused to burn). Still, it does have biostimulative properties. So the effect most likely depends on tranmsitter substances from superficial blood vessels. Conventional LLLT wavelengths combine this effect with "direct hits" in the deeper lying affected tissue.
Answer: The depth of penetration of laser light depends on the light's wavelength, on whether the laser is super-pulsed, and on the power output, but also on the technical design of the apparatus and the treatment technique used. A laser designed for the treatment of humans is rarely suitable for treating animals with fur. There are, in fact, lasers specially made for this purpose. The special design feature here is that the laser diode(s) obtrude from the treatment probe rather like the teeth on a comb. By delving between the animal's hair, the laser diode's glass surface comes in contact with the skin and all the light from the laser is "forced" into the tissue. A factor of importance here is the compressive removal of blood in the target tissue. When you press lightly with a laser probe against skin, the blood flows to the sides, so that the tissue right in front of the probe (and some distance into the tissue) is fairly empty of blood. As the haemoglobin in the blood is responsible for most of the absorption, this mechanical removal of blood greatly increases the depth of penetration of the laser light. It is of no importance whether the light from a laser probe held in contact with skin is a parallel beam or not in contact treatment. There is no exact limit with respect to the penetration of the light. The light gets weaker and weaker the further from the surface it penetrates. There is, however, a limit at which the light intensity is so low that no biological effect of the light can be registered. This limit, where the effect ceases, is called the greatest active depth. In addition to the factors mentioned above, this depth is also contingent on tissue type, pigmentation, and dirt on the skin. It is worth noting that laser light can even penetrate bone (as well as it can penetrate muscle tissue). Fat tissue is more transparent than muscle tissue. For example: a HeNe laser with a power output of 3.5 mW has a greatest active depth of 6-8 mm depending on the type of tissue involved. A HeNe laser with an output of 7 mW has a greatest active depth of 8-10 mm. A GaAlAs probe of some strength has a penetration of 3.5 cm with a 5.5 cm lateral spread. A GaAs laser has a greatest active depth of between 20 and 30 mm (sometimes down to 40-50 mm), depending on its peak pulse output (around a thousand times greater than its average power output). If you are working in direct contact with the skin, and press the probe against the skin, then the greatest active depth will be achieved.
Answer: The answer is no. No mutational effects have been observed resulting from light with wavelengths in the red or infra-red range and of doses used within LLLT. What happens if I treat someone who has cancer and is unaware of it? Can the cancer's growth be stimulated? The effects of LLLT on cancer cells in vitro has been studied, and it was observed that they can be stimulated by laser light. However, with respect to a cancer in vivo, the situation is rather different. Experiments on rats have shown that small tumours treated with LLLT can recede and completely disappear, although laser treatment had no effect on tumours over a certain size. It is probably the local immune system which is stimulated more than the tumour. The situation is the same for bacteria and virus in culture. These are stimulated by laser light in certain doses, while a bacterial or viral infection is cured much quicker after the right treatment with LLLT.
Answer: You will have a bio-suppressive effect. That means that, for instance, the healing of a wound will take longer time than normally. Very high doses on healthy tissues will not damage them.
Answer: You should not treat cancer, for legal reasons. Pregnant women is not a counter indication, if used with common sense. Pace makers are electronic devices, do not respond to light. The most valid counter indication is lack of medical training.
Answer: Due to increased circulation there is usually an increase of 0.5-1 centigrades locally. The biological effect have nothing to do with heat. GaAlAs lasers in the 50-500 mW range may cause a noticable heat sensation, particularly in hairy areas.
Increase of heat depends on many factors as e.g. body part, skin type, wavelength, power, energy density.
Important Note : Heating (even burning) can occur
Answer: Monochromatic non coherent light, such as light from LED's can be useful for superficial tissues such as wounds. In comparative studies, however, lasers have shown to be more effective than monochromatic non coherent light sources. Non coherent light will not be effective in deeper areas.
Answer: No. The length of coherence, though, is split into very small coherent "islands" called specles. These specles remain coherent and will penetrate deeply into the tissue.