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Lasers have been previously been used for dental applications, however there remain issues with thermally-induced
cracking. In this paper we investigate the impact of pulse length on CO2 laser ablation of human dental enamel.
Experiments were carried in vitro on molar teeth without any modification to the enamel surface, such as grinding or
polishing. In addition to varying the pulse length, we also varied pulse energy and focal position, to determine the most
efficient ablation of dental hard tissue and more importantly to minimize or eradicate cracking. The maximum
temperature rise during the multi pulse ablation process was monitored using a set of thermocouples embedded into the
pulpal chamber.
The application of a laser device in dental surgery allows removal of tissue with higher precision, which results in
minimal loss of healthy dental tissue. In this study we use an RF discharge excited CO2 laser operating at 10.6μm. The
wavelength of 10.6 μm overlaps with a phosphate band (PO3-4) absorption in dental hard tissue hence the CO2 laser
radiation has been selected as a potential source for modification of the tissue. This research describes an in-depth
analysis of single pulse laser ablation. To determine the parameters that are best suited for the ablation of hard dental
tissue without thermal cracking, a range of pulse lengths (10-200 μs), and fluences (0-100 J/cm2) are tested. In addition,
different laser focusing approaches are investigated to select the most beneficial way of delivering laser radiation to the
surface (divergent/convergent beam).
To ensure that these processes do not increase the temperature above the critical threshold and cause the necrosis of the
tissue a set of thermocouples was placed into the pulpal chambers. Intermittent laser radiation was investigated with and
without application of a water spray to cool down the ablation site and the adjacent area. Results show that the
temperature can be kept below the critical threshold either by using water spray or by decreasing the repetition rate. We
demonstrate that CO2 laser pulses with pulse lengths in the regime of 10 μs can provide precise enamel tissue removal
without introducing any unwanted thermal damage.
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