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ePaper created 2016-10-12, 10:31:46 | version 1.38.0
research | 07 3 2016 laser output available up to now, surgical applications of the blue light lasers have not yet been realised to a significant extent. However, approaches to this have already been available in literature for a number of years.6, 9 The modification of diode laser technology in dentistrytowardssystemswithemissionintheblue light spectrum can open a large number of advan- tages in comparison to the established diode laser technology in the NIR as a result of the biophysical properties. This includes, among others, a huge working effectiveness at considerably lower power settings. Because of this, for instance the side ef- fects can be reduced considerably. Furthermore, thereisafavourableeffectonwoundhealing.10 An- timicrobial effects are highly exceeded in compari- son with infrared radiation and promote an effec- tivedisinfectionofcontaminatedtissueareas.11-13 In this way, the blue light may prevent wound infec- tions. Clinical experience with radiation in the re- gion of 450 nm is already available in many disci- plines of medicine without any disadvantages of these wavelengths.14-16 Biophysical properties of 445 nm laser radiation The possible use of a laser application system with an emission wavelength of 445 nm for surgical pro- cedures on oral soft tissues (incision/excision as well as bacterial decontamination and haemostasis) re- quiresahighlevelofabsorptionoftheradiationused inthesetissuestoworkeffectively.Theseareprimar- ily well perfused gingival tissues of the oral mucosa including the subepithelial connective tissue. Exam- ples are the free gingiva, attached gingiva, alveolar mucosa,buccalmucosa,palatalmucosa,andmucosa of the tongue. The absorption constant for a wavelength of 445 nm shows a high level of absorption in melanin and haemoglobin (Fig. 1). Furthermore, the absorp- tion in collagen also increases significantly in the wavelength range of blue light (Fig. 2). Absorption in water, however, is lower compared to conventional NIRsurgicaldiodelasers.Inaddition,scatteringinthe blue light spectrum also increases (Fig. 1). These bio- physical effects mean that, in comparison to the in- frareddiodelasers,theworkingeffectivenessmaybe considerably higher at the same power settings as a resultofthehugeincreasedabsorptioninthetissues. With regard to tissue vaporisation, intensive absorp- tion may improve cutting effects. The increased level ofabsorptionincomparisonwithconventionaldiode laserscouldleadtoareductionofthethermalsideef- fects outside the work area. The specific absorption constantsrelatedtobluelightarethereforeabasisfor aneffectivelimitingofbiologicalsideeffectsoutside the radiation field. The absorption of light at 445 nm in water is low. Thismeansthat,duringsurgicalprocedures,theradi- ation energy is almost completely transmitted through the non-pigmented mucin layer. Therefore, the cutting procedure starts immediately; there is no need for a so-called initialisation of the incision needed in cases by using diode lasers in the NIR. Figs. 3a–d: Test setup for the implementation of standardised gingiva incisions: a) gingiva sample (mandibula, soft tissue and bone/pig); b) sample fixed on the optical bench; c) example of irradiated sample (HF versus 980 nm, 3 W cw, 5 mm/s); d) histological section of Fig. 3c (HE-staining), 1: HF surgery, 2 & 3: laser 980 nm, 3 W, cw. Fig. 3a Fig. 3c Fig. 3b Fig. 3d 32016