Erbium lasers, by their nature of being well absorbed by water & hydroxyapatite, originally were considered primarily hard tissue lasers. It must remembered that the primary chromophore of the erbium family of lasers is water in the target tissue, and the largest component of soft tissue is water. Laser physics and absorption curves of various tissues have shown that the erbium family of lasers ablate soft tissue by the same mechanism as hard tissue. The laser energy from the infrared beam is converted into local thermal energy, and this energy creates a massive expansion in the target chromophore of water. The resulting micro explosions result in thin layers of tissue ablation. The erbium laser soft tissue removal process results in a ‘‘shaving’ ’ or ‘‘planing’ ’ of the tissue that clinically appears different than the deeper penetrating ablation process seen with soft tissue lasers(Nd:YAG & Diode), its postulated that during the cutting of human mucosa, the Er:YAG targets the water molecules rather than the collagen matrix. The energy causes the water molecules to be heated into steam,which in turn strains and fractures the collagen matrix in the extracellular environment.The depth of penetration of an Er:YAG laser using a 200- to 400 microsecond pulse width is in the range of 5 t o 40 micron. There is as little as 5 micron of residual thermal damage .This penetration depth is different than the soft tissue lasers (diodes , Nd:YAG), where tissue effects can be as deep as 500 micron or more . The collateral damage produced by the Er:YAG laser is minimal because the energy is absorbed in water and thermal damage is small (no charring), which may result in improved healing of the area. there is less collagen remodeling and, in turn, faster healing with minimal scar tissue presenting after erbium laser soft tissue surgeries.Diode lasers (810–980 nm ), unlike the erbium family, are very well absorbed in melanin and hemoglobin. These wavelengths will pass through water and penetrate much deeper into the soft tissue. Moreover, these wavelengths achieve hemostasis much better than the erbium lasers, which are not well absorbed by these chromophores. The erbium family is not the ideal wave length for soft tissue surgeries in which ideal hemostasis is desired .to enhance the hemostatic effect when working with laser we don't use water spray and also we use the VLP duration .
The degree of difficulty with hemostasis seems to be greatest in cases where the soft tissue initially is inflamed. Although the erbium laser can be used for gingivectomies, gingivoplasties, frenectomies, vestibuloplasties , extensional procedures, crown lengthening, incisions and drainage, implant exposures during second-stage surgery, apthous ulcer palliative treatments, and the removal of melanin pigmentation, the clinician must show care to assure that no collateral thermal damage may occurs in adjacent tissues such as bone, cementum, or dentin due to using the erbium laser for soft tissue procedures
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| Er:YAG Ablation Of Hard Tissue |
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Gingivectomy
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Recommended power settings for the erbium family of instruments
Enamel: 4–8W (with water SSP,VSP)
Dentin : 2–5W (with water SSP,VSP)
Caries: 1–3W (with water SSP,VSP)
Bone: 1.5–3W (with water SSP,VSP)
Soft tissue : 1–3W (contact without water VLP)
Dr.Zohairy
