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ePaper created 2016-10-12, 10:31:46 | version 1.38.0
| research 10 laser 3 2016 positioner that had been set to a feed rate of 1 and 5 mm/s to simulate constant cutting speeds. These cutting speeds were chosen to cover the spectrum of conventional laser applications. The specimens were irradiatedusingthesamelaserapplicationsystem(di- ameter320 μm)bothwithawavelengthof445 nmand alsowitha980 nmdiodelaserincontactmode.Linear incisions were carried out starting from the starting line that had been marked beforehand. The incisions were carried out with a 445 nm laser with a power of 1.5and2 Wcontinuouslyandwitha980 nmlaserwith a power of 3 W in the same mode. Incisions that had beenmadeadditionallywithascalpelandwithHFsur- geryservedasreferences(Fig.3c).Fromthegingivaof this sample, after removal of the soft tissue from the bone substrate, paraffin sections in HE-staining were examined under a light microscope (Fig. 3d). The comparative histological evaluation of the specimens led to the following results: 1. The histological changes in the cutting area at wavelengths 445 nm and 980 nm are qualitatively identical. 2. The width of the coagulation zone and the cutting depth depends on the cutting speed (for both wavelengths and their parameters). 3. The width of the coagulation zone is, at the same cutting speed, larger at 980 nm compared to the 445 nm.With445 nm,thewidthofthecoagulation zone increases with rising power, in particular at a low cutting speed. 4. At a high cutting speed, the cutting depth is the samefor445 nmat2 Wand980 nmat3 W(output power). 5. Thewidthofthecoagulationzoneissmallerwithall 445 nm parameters than with 980 nm. 6. TheHFsurgicalprocedureledtohistologicalresults that are comparable with 980 nm. With regards to “freehand” ex vivo procedures in pigs, 445 nm incisions (2 W, cw) demonstrated good cutting effectiveness and haemostasis for incisions ofdifferentdepths(Fig.4).Tissuevaporisationbegins immediately after activating the laser. The working arearemainedclearduetohaemostasis.Thehistolog- ical analysis (Fig. 4) shows three surgical incisions with differing depths. No mechanical effects (clefts/ tissue deformation) were observed. The carbonising layeronthetissuesurfacetreatedisverynarrow(ap- prox. 1 μm). Around the incision, a zone of increased staining, which was clearly differentiated from the unchangedtissue,appeared.Nounderminingblister- ingwasnotedintheepitheliumintheareaofthecut- ting edge. The morphological structure of the tissue beneath the incision area is preserved despite the in- creaseddiscolouration.Vesselsinthisareadisplayno ruptures (Fig. 5). No red blood cells were detected outside of the vessels in the tissue. Fig. 7a Fig. 7b Fig. 7c Fig. 7d Fig. 7e Figs. 7a–c: Test setup and examples of the monolayer culture as well as the fluorescence detection of cytoskeletal changes and DNA double strand breaks: a) sample mounted on a xyz-translation stage; b) sample holder with coverslip; c) laser incision of the monolayer with a 445 nm diode laser (2W, cw), thermal effects at the central irradiation zone (staining HE); d) staining of the cytoskeleton after 445 nm laser irradiation with fluorophore conjugated phalloidine; no adverse effects (Alexa Fluor phalloidin, DAPI); e) immunofluorescence microscopy: DNA double strand breaks characterised by red fluorescent foci (p-H2aX) occurs only after UV-irradiation as positive control. 32016