Effects of Nd: and Ho:yttrium-aluminium-garnet lasers on human dentine fluid flow and dental pulp-chamber temperature in vitro.

Dentine specimens were prepared from freshly extracted third molars and initial permeability measured. Each specimen was subjected to Nd:yttrium-aluminium-garnet (YAG) (1.06 or 1.32 microns wavelength) or Ho:YAG (2.10 microns wavelength) laser energy while temperatures in the pulp chambers were recorded. Permeability was again measured and the surfaces examined by scanning electron microscopy. Six crown segments were used for each laser variable and eight permeability measurements were taken before and eight after laser exposure, while temperature was recorded during treatment. All wavelengths reduced permeability but temperature rises were high enough to have caused pulpal damage, indicating that shorter treatment times and lower power settings may be necessary if used in vivo.