Influence of Output Energy and Pulse Repetition Rate of the Er:YAG Laser on Dentin Ablation

Abstract

Objective: We sought to improve the efficiency of dentin ablation with the Er:YAG laser by investigating the effects of output energy and pulse repetition rate on ablation. Background Data: The Er:YAG laser is superior to other lasers in ablating dental hard tissues. However, the factors affecting the efficiency of ablation with an Er:YAG laser remain unclear. Methods: Fifty bovine root dentin plates were irradiated with an Er:YAG laser at an output power of 1.0 W, 1.5 W, or 2.0 W under a water spray while moving the plate at 1 mm/sec. After irradiation, the depth and volume of each ablated site were measured by laser microscopy and the ablated surfaces were examined by scanning electron microscopy. Results: The output power showed a strong positive correlation with the depth and volume of ablation. The output energy had much more pronounced effects on the depth and volume of ablation compared to the pulse repetition rate. The shape of the ablated site varied with the output power, and no cracking or vitrification was observed under the irradiated dentin. The most effective parameters for dentin ablation were an output power of 2.0 W, with an output energy of 80 mJ/pulse at 25 pulses per second (pps) or 100 mJ/pulse at 20 pps. Conclusion: These findings suggest that the output energy is the main factor affecting the efficiency of dentin ablation with an Er:YAG laser. We propose that the efficiency of dentin ablation can be improved by choosing an optimal combination of output energy and repetition rate. 189

Surface Treatment by Different Parameters of Erbium:Yttrium–Aluminum–Garnet (Er:YAG) Laser: Scanning Electron Microscope (SEM) Evaluation

“…Another study has investigated the influence of different output powers of Er:YAG, concluded that the output power is important in ablation efficiency and creates different shapes such as box, polygonal and bowel shaped architecture. 11 SEM images of experimental groups showed recrystallization areas around dentinal tubules. These areas form after that the laser irradiated peritubular dentin begins to cool down.…”

Ablation of human dentin with Er:YAG laser

“…A.Igarashi et al [ 4] illustrated that the depth and volume tended to increase at higher output energies and lower pulse repetition rate. Our study doesn't consider the effect of pulse repetition rate and it needs to be clarified in further studies.…”

“…The cross section of ablation crater presented a box type and the crater bottom was relatively flat (Fig.2 (b)). In the study by A.Igarashi et al [ 4], the ablated sites were divided into box, polygonal, and bowl types. The shape of the ablated site varied with the output power.…”

Minimally invasive erbium flap (MINIETM flap)—a retrospective surgical treatment for chronic periodontitis

“…When studying different parameters and settings, Igarashi found that output energy had a much stronger effect on the depth and volume of ablation, when compared to the repetition rate [45]. He found that 120 mJ energy exclusively removed the demineralized tissue providing a more flattened surface, when compared to the higher energy outputs.…”