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25. INTERNATIONALE JAHRESTAGUNG DER DGL LASER START UP 2016 42 laser 3 2016 Investigations of radicular dentin permeability and ultrastructural changes after irradiation with dual wavelength (Er,Cr:YSGG and 940 nm diode laser) Tamara Sardar Al-Karadaghi, Dr René Franzen, Hussein A. Jawad and Prof. Dr Norbert Gutknecht, Aachen/Germany The aim of this study was to assess the effectiveness of dual wave- length (2,780nm Er,Cr:YSGG, 940nm diode) laser in the elimination of smear layer, comparing it to Er,Cr:YSGG laser in terms of radicular dentin permeability and ultrastructural changes of root canal walls. 51 sound single-rooted extracted teeth were instrumented up to size F4 and divided into three groups: group Co (non-irradiated samples), group A (irradiated with Er,Cr:YSGG laser), group B (irradiated with the dual wavelength laser). Afterward, the roots were made externally impermeable, filled with 2% methylene blue dye, divided horizontally into three segments, reflecting the cervical, middle, and apical thirds then examined under microscope. Using analytical software, the root section area and dye penetration area were measured, and then, the percentage of the net-dye penetration area was calculated. Addi- tionally, scanning electron microscope investigations were accom- plished. Analysis of variance (ANOVA) showed significant differences between all groups over the three root thirds. Dye permeation in the dual wavelength laser group was significantly higher over the whole root length, cervical, middle, and apical, compared to Er,Cr:YSGG laser group and non-irradiated samples (p < 0.001). Scanning elec- tron micrographs of dual wavelength irradiated samples showed a distinctive removal of smear layer with preservation of the annular structure of dentinal tubules. Er,Cr:YSGG laser root canal irradiation produced an uneven removal of smear layer and inefficient clean- liness especially in the apical third. There was no sign of melting or carbonisation. Within the studied parameters, root canal irradiation with dual wavelength laser increased dentin permeability. Comparison of diode lasers in soft-tissue surgery using cw- and superpulsed mode—An in vivo study Dr Ralf Borchers, Bünde/Germany Dental soft-tissue surgery by diode lasers in cw-mode often causes carbonisation of the tissues with following necrosis and a delay of wound healing. In vitro studies have already shown that superpulsed diode-laser surgery has much less disadvantages for the tissues in an histological approach. The purpose of this study was to investigate in vivo if the superpulsed mode of operation can realise an improvement for surgeon and pa- tient in soft-tissue surgery. 26 patients were treated by diode lasers in different modes of operation for soft-tissue surgery. Twelve patients were treated by the superpulsed elexxion claros diode laser: 810nm; 10–50W peak; 10–20µs pulse duration; 12,000–20,000Hz; 400µm fibre. 14 patients were treated by Vision MDL-10 diode laser: 980nm; 2.5W; cw-mode and also a 400-µm fibre. Clinical treatment was documented by photos and question- naires for patients and surgeons. Questions concerned: carbonisa- tion, coagulation, cutting speed, pain, swelling, bleeding, need for drugs, functional reduction and fibrin layer on wounds—during treat- ment, directly after treatment, after one day, after three days and after one week. Clinical observations and the questionnaires showed significant differences between cw-mode and superpulsed diode- laser treatment in surgery in most cases. It was shown that super- pulsed diode-laser surgery is superior to continuous-wave treatment. Carbonisation and thermal damage of the tissues can be reduced to a minimum, therefore healing is faster than in cw-mode surgery. The generation of a soft-tissue cut is faster and more precise. Pa- tients have less pain; in amount and duration. The need of drugs is reduced. There are less functional restrictions and there is less swell- ing. The advantages of superpulsed mode of operation for soft-tissue diode-laser surgery are evident. Continuous-wave mode should no longer be implemented in diode-laser surgery. 32016