Study compares ablation performance between Er:YAG and Er,Cr:YSGG
14 March 2008
It was concluded from the study results that the novel profilometric methodology to measure ablated volumes is highly accurate and repeatable. Furthermore, measurements are made under realistic conditions and are identical to manually administered laser treatments by a dental practitioner. The profilometric measurements show that of the two wavelengths, operating at identical pulse energies, Fotona's VSP-shaped Er:YAG laser ablates, with a factor of up to 2, more efficiently per pulse than the Er,Cr:YSGG laser. It was not possible to make further comparative measurements of the two technologies at pulse energies greater than 300mJ as these pulse energies are not attainable with the Waterlase MD system used in the study's setup.
Measurements of ablation speed show that the Er:YAG laser ablates 3.7 times faster in dentine and 5 times faster in enamel compared to the Er,Cr:YSGG laser. Moreover, during the measurements it was observed that the Er:YAG laser did not cause any thermal damage to tooth tissue, while thermal damage in the form of brownish discolored spots was observed in dentine with the Er,Cr:YSGG laser.
The author attributes the measured differences in ablation efficiency and speed between the two laser sources to (1) the difference in water absorption coefficients in hard dental tissue, (2) the current limitation of Er,Cr:YSGG lasers to pulse widths above 600μs and (3) pulse shape, where VSP-technology keeps the power within Er:YAG laser pulses constant. It is also noted that these attributes only partly explain the disparities. Another aspect is the difference in performance capabilities (Fidelis Plus III 20W versus Waterlase MD 8W) between the two laser systems used in the experimental set up, reports the author.
