Residual heat deposition in dental enamel during IR laser ablation at 2.79, 2.94, 9.6, and 10.6 μm

Abstract

Residual heat deposition can be markedly reduced by using CO(2) laser pulses of less than 20 microsec duration and shorter Q-switched Er:YAG and Er:YSGG laser pulses for enamel ablation.

Impact of Er:YAG laser pulse duration on ultra-structure of dentin collagen fibrils

“…While in the cavity preparation protocol, the ultra-structural changes were more accentuated; these results were in accordance with previous studies [27,29]. As residual heat accumulation is proportional to fluency and pulse duration parameters [17], the higher the parameter used, the greater the detected changes.…”

“…Thus, the null hypothesis was rejected. This parameter with short pulse can provide high ablation speed and minimal residual heat deposition into the tooth [32], and this finding adds value to Fried et al [17] who stated that residual heat deposition was reduced when shorter pulses were used during Er:YAG laser irradiation.…”

“…Longer pulses do not allow time enough for thermal relaxation required by the tissue [17]. Thus, interaction time between emitted energy and target tissue is longer, allowing part of the absorbed energy/heat to be diffused to adjacent sites far from irradiated target tissue.…”

“…The water spray initiates the ablation process and increases the ablation rate efficiency [14] by assisting the removal of loosely attached deposits of non-apatite mineral phase [15,16] which interferes with subsequent laser pulses [17]. Also, the endogenous water increases the degree of ablation efficiency by eliminating the free water component from the tissue and maintaining the interprismatic stored water or bound OH components [18].…”

Average-power mediated ultrafast laser osteotomy using a mode-locked Nd:YVO[sub 4] laser oscillator

“…For example, continuous-wave ͑CW͒ and long-pulse ͑ns to ms͒ infrared lasers, such as the CO 2 laser, Ho: YAG laser, and Er: YAG laser, were used for heating and evaporating osseous tissues near the 2.9-m water absorption wavelength or the 10-m calcium-phosphate absorption wavelength. [1][2][3][4] One major disadvantage associated with laser thermal ablation is significant carbonization and collateral damage to surrounding tissues. In the short pulse limit, an ultrafast laser with a ps or fs pulse width cuts or drills a dielectric material through multiphoton and avalanche ionization or hydrodynamic expansion of plasma induced by the high electric field in the laser pulse.…”