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ePaper created 2017-04-20, 12:10:03 | version 1.38.0
sary to minimise the thermal increase and to avoid a tissue temperature rise of more than 4–5 degrees Celsius.6 In clinical applications, photobiomodulation has been used to successfully induce wound and bone healing7–10, for pain reduction11 and for anti-inflam- matory effects12–14. Little is known about the use of the neodymium-doped yttrium aluminium garnet (Nd:YAG) laser in a biostimulatory mode. Most in- vestigations have centred on the use of laser energy in the range of 400 nm to 980 nm. In this range of wavelengths, photons can penetrate ef- fectively to reach deeper structures. Nd:YAG, at a wavelength of 1,064 nm, is near this window and exhibits some advantages. In terms of penetration of the radiation, longer wavelengths, such as pro- duced by the (infrared) diode laser and Nd:YAG la- ser, penetrate as much as 6 millimetres, whereas laser energy with a shorter wavelength, such as red light produced by the He-Ne laser, has significantly less penetration.15 Recently, Usumez et al. demonstrated that low- level Nd:YAG laser therapy accelerates the wound healing process by changing the expression of PDGF and bFGF, genes responsible for the stimulation of cell proliferation and fibroblast growth.16 Significant effort has been made to clarify the parameters of deposited energy that will effectively promote positive change in individual cells while avoiding negative effects. Karu observed that high fluencies cause the destruction of photoreceptors which is accompanied by growth inhibition and cell lethality.17 Other researchers have also demonstrated that irradiation with fluencies higher than 10 J/cm2 damages DNA.18,19 Finally, Bensadoun suggested the optimal dose is in the range of 2–3 J/cm2 for prophy- laxis and not more than 4 J/cm2 for therapeutic ef- fects, and recommended application over a single spot on a lesion rather than using a scanning motion over the entire lesion surface.20 The World Associa- tion of Laser Therapy (WALT) has stated that applying energy in the range from 3 J/cm2 to 10 J/cm2 will pro- mote effective biostimulation while avoiding bio- inhibitory effects.21 While this range of energy density seems well doc- umented, achieving this goal is problematic. Radiated energy must reach target cells at this intensity level to be effective. Since the cells being targeted often lie deep within the tissue, absorption and scattering in overlying structures has a very significant effect on photon distribution. Laser energy density and distri- bution at the tissue surface is a poor predictor of deeper tissue distribution. A method of delivering photons to a group of individual cells, often deep Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 laser_industry Fig. 8: Situation before the mucogingival surgery. Fig. 9: Creation of the recipient bed. Fig. 10: Irradiation points after graft stabilisation. Fig. 11: Situation after 14 days. Fig. 12: Situation after 42 days. laser 3+4_2016 3333