Keimreduzierende Tiefenwirkung des ErCr:YSGG-Lasers auf Enterococcus faecalis innerhalb des Wurzelkanalwanddentins : ein In-vitro-Versuch

The aim of this study is to examine the bacterial effects of ErCr:YSGG laser irradiation and its dependence of the working tip angulation. Also the morphologic changes of the lasered areas are valued with scanning electron microscopy. After cleansing and shaping extracted single root human teeth to ISO 40, longitudinal section dentin slices of different thicknesses (0,1mm, 0,15mm, 0,3mm, 0,5mm, 1mm) were sterilized and inoculated with 0,001ml of an enterococcus faecalis suspension. The contralateral side of the dentin slices were irradiated under an acute angle of 5° using the ErCr:YSGG laser (lambda=0,00278mm) adjusted to 12,5mJ at which a control group served unlasered. The bacteria were then removed from the dentin slices using vibration in 1 ml sterile and isotonic NaCl-solution and cultured on Columbia-agar. In spite of the small energy of 12,5mJ there was found a significant bacterial reduction till the dentin slice of 0,5mm. The dependence of the working tip angulation of 5 degree and 90 degree was examined with sterile diascopes to assume equal conditions. It was proved a significant difference. The scanning electron microscopy examination shows almost clean areas without bacterial debris or smear layer. The openings of the dentinal tubules were clearly visible. The intertubular dentin seemed to be ablate more than the peritubular dentin