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In the past decades, many efforts have been made to replace mechanical tools in oral applications by various
laser systems. The reasons therefore are manifold: i) Friction causes high temperatures damaging adjacent tissue.
ii) Smear layers and rough surfaces are produced. iii) Size and shape of traditional tools are often unsuitable for
geometrically complicated incisions and for minimum invasive treatment. iv) Mechanical damage of the remaining
tissue occurs. v) Online diagnosis for feedback is not available.
Different laser systems in the µs and sub-&mrg;s-pulse regime, among them Erbium lasers, have been tested in the
hope to overcome the mentioned drawbacks and, to some extent, they represent the current state of the art with
respect to commercial and hence practical application. In the present work the applicability of scanned ultrashort
pulse lasers (USPLs) for biological hard tissue as well as dental restoration material removal was tested. It
is shown that cavities with features superior to mechanically treated or Erbium laser ablated cavities can be generated
if appropriate scan algorithms and optimum laser parameters are matched. Smooth cavity rims, no microcracks,
melting or carbonisation and precise geometry are the advantages of scanned USLP ablation. For bone
treatment better healing conditions are expected as the natural structure remains unaffected by the preparation
procedure.
The novelty of this work is represented by a comprehensive compilation of various experimental results intended
to assess the performance of USPLs. In this context, various pulse durations in the picosecond and femtosecond
regime were applied to dental and bone tissue as well as dental restoration materials which is considered to be
indispensable for a complete assessment. Parameters like ablation rates describing the efficiency of the ablation
process, and ablation thresholds were determined - some of them for the first time - and compared to the corresponding
Erbium values. The morphology of the tissue surfaces remaining after laser preparation was investigated
and the surface roughness was evaluateded. Selective ablation was stressed and the temperature impact induced
by USPLs was analyzed. Due to the limited space only a selection of results can be presented.
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