Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2016-10-12, 10:31:46 | version 1.38.0
| research 12 laser 3 2016 wavelengths. The basis for these effects are thermal and photochemical effects, e.g. known from aPDT (antimicrobial photodynamic therapy). This effect hasbeenrecognisedforanumberofyearsforNIRla- ser irradiation. Studies in basic medical research have shown that bluelightalsohasanantimicrobialeffect.11 Asaresult, alasersystemwithawavelengthof445 nmhasasig- nificant potential for antimicrobial effects if such a laser is used within the scope of surgical indications. Comparativestudieswerecarriedoutwhetherthe antimicrobial effect of a surgical blue light laser was comparablewiththeantimicrobialeffectsofinfrared laser irradiation with a wavelength of 980 nm.24 In particular, it was to be investigated whether decon- tamination of the surgical field with low thermal ef- fects is basically possible. To test this, agar plates werecoatedwithtestbacteria(E.faecalisandS.sali- varius) and irradiated with laser light at 445 nm and 980 nm. Identical application systems were used for this purpose. After laser irradiation, the agar was coated with an overlay agar that contained the spe- cific nutrient components for the bacterial growth. Furthermore, the temperature of the irradiated area wasmeasuredusingathermographiccameraduring irradiation. Concerning the temperature change during the irradiation phase, only a small tempera- tureincreasehadbeenobservedwhenthelaserradi- ation in the blue light spectrum was used. By con- trast, there were significant temperature increases during irradiation with the 980 nm laser (Fig. 8). Un- der identical test conditions, bactericidal effects were demonstrated in the culture trials by the use of a 320 μm fibre diameter at 445 nm wavelength even at low output power (0.1 W) in non-contact mode. At 980 nm irradiation, bacterial growth was firstly affectedat2 Woutputpower.Theeffectswereinde- pendent from the test species (E.faecalis and S.sali- varius) that were used for this investigation. The re- sults show a very high potential for a possible antibiotic treatment that can be achieved with only low-level stress to the region adjacent to the irradi- ated area—a maximum 3°C temperature increase in theseinvestigations—incomparisontoinfraredlaser irradiation.Theseresultsconcurwithanumberofba- sic studies that assume a sustained antimicrobial ef- fect of blue light.11-13 This concomitant effect pro- vides clinically relevant support for the use of a 445 nm laser for surgical indications.10 Haemostasis Due to the strong adsorption of blue laser light in haemoglobin, pronounced coagulation effects were expected. To investigate coagulation, porcine whole bloodintestsampleswithathicknessof150μmwere examined (Fig 9). During irradiation with blue laser light,evenwithanoutputpowerof0.1 Wincwmode, appliedviaafibrewithadiameterof320 μmatanob- ject distance of 10 mm, clearly visible coagulation ef- fectsoccurredsuddenly(Fig.9).24 Theseexperimental results confirmed the prediction regarding the high haemostaticpotencyofthenewbluelightdiodelaser system (Fig. 1). This effect provides sustainable sup- porttoincisionandexcisionprocedures,inparticular for patients with anticoagulation therapy. Case report of surgical applications Basedontheexistinginvitroinvestigations,aclin- ical study was required to prove the particular prop- ertiesofbluelightlaserradiationinclinicalsituations. Fig. 10a Fig. 10b Fig. 10c Fig. 11a Fig. 11b Fig. 11c Fig. 11d Figs. 10a–c: Deep crown fracture 45 in a multi-morbid patient; gingivectomy using 445 nm (1,5 W, cw, 320 µm Ø); a) OP situs before surgery; b) one week post-op; c) three months post-op. Figs. 11a–d: Caries lesion up to the furcation area; adhesive restauration including endodontic treatment using 445 nm (1,5 W, cw, 320 µm Ø); a) location of the caries lesion, b) extensive excision of soft tissue, no bleeding after gingivectomy; c) adhesive restauration after finishing the margin of the cavity (removing of the carbonised layer with hand instrument); d) situation four weeks after ves- tibular composite restauration and endodontic treatment. 32016