Ablation thresholds of healthy dentin were measured engaging four different pulsed laser systems, emitting in the near ultraviolet (wavelength 355 nm, wavelength 377 nm), in the near infrared (wavelength 755 nm), and in the mid infrared (wavelength 2.9 micrometers ) spectral region. A pulse duration of 200 ns was used during experiments with the Alexandrite-laser (wavelengths 377 nm and 755 nm) whereas at the wavelength 355 nm pulse duration was fixed at 9 ns and at wavelength 2.9 micrometers pulse duration was set to 200 ns again. Two well defined ablation thresholds could be detected using laser wavelengths which are well absorbed by the target (near UV, mid infrared). Due to low absorption of near infrared wavelengths in healthy dentin, high fluences must be engaged for ablation of healthy dentin. In this spectral region only a more or less statistically appearing ablation threshold was observed. Caused by high fluences unpredictable plasma formation takes place. Even so, short pulse duration leads to high peak power, thus originating plasma.