Drilling and surface processing of bone and tooth tissue belongs to standard medical procedures (bores and embeddings
for implants, trepanation etc.). Small circular bores can be generally quickly produced with mechanical drills. However
problems arise at angled drilling, the need to execute drilling procedures without damaging of sensitive soft tissue
structures underneath the bone or the attempt to mill small non-circular cavities in hard tissue with high precision. We
present investigations on laser hard tissue "milling", which can be advantageous for solving these problems.
The processing of bone is done with a CO2 laser (10.6 &mgr;m) with pulse durations of 50 - 100 &mgr;s, combined with a PC-controlled
fast galvanic laser beam scanner and a fine water-spray, which helps keeping the ablation process effective
and without thermal side-effects.
Laser "milling" of non-circular cavities with 1 - 4 mm width and about 10 mm depth can be especially interesting for
dental implantology. In ex-vivo investigations we found conditions for fast laser processing of these cavities without
thermal damage and with minimised tapering. It included the exploration of different filling patterns (concentric rings,
crosshatch, parallel lines, etc.), definition of maximal pulse duration, repetition rate and laser power, and optimal water
spray position. The optimised results give evidence for the applicability of pulsed CO2 lasers for biologically tolerable
effective processing of deep cavities in hard tissue.