Lasers - Lecture notes 11 PDF

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Summary

Introduction to dental lasers, uses, risks, radiation, light, stimulated emission, amplification, components of the lasers, tissue interaction, uses, applications for the RDH and DDS, laser safety, and research....

Description

Lasers Intro ● ● ●

Controversial, yet interesting “Evidenced based practice” Evolving field, changing frequently

History ● First laser specifically designed for dentistry marketed in 1989 ● In medicine, technology first used in 1960s ● Carbon dioxide lasers used for general and oral surgery in the 1980s ● Less than 10% of dentists worldwide use lasers Laser is an acronym for: light amplification by stimulated emission of radiation Light ● Basic unit of light energy is a photon ● Normal light and laser energy are very different ○ Normal light = sum of many colours ○ Laser light = monochromatic ● Laser light is coherent - all waves produced are identical ● 2 important properties of a laser beam ○ Amplitude - intensity of the wave ○ Wavelength - related to physical size of the wave - important to how it interacts with tissue Stimulated emission ● When energy is abstracted by the electrons of an atom, excitation occurs ● Since natural order prefers “resting states”, this energy is released ○ Called spontaneous emission ● Stimulated emission = Another quality excited photon travelling in the field of the excited atom above = the release of more energy Amplification ● With constant “stimulated emission” = more identical, energized photons = further spread of this wave ● Within the device, a pumping mechanism exists ○ Offers constant supply of energy to photons ○ Maintains excitation ○ Passing through the medium increases the power and amplifies the beam Radiation ● The laser energy produced falls somewhere on the electromagnetic spectrum

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All laser devices have wavelengths larger than 350 mm Will only cause excitation and heating of the tissue with which they interact

Yellow line on the chart above ^^ - non-ionizing vs ionizing

Laser Components ● Optical cavity at centre = contains active medium ● Active medium comprised of chemical elements, molecules or compounds

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Lasers usually named based on the active medium Container of gas, crystal, solid-state semiconductor When stimulated, produced certain wavelengths Primary gaseous active medium is CO2 Solid state semiconductor lasers ○ Multiple layers of metals ■ Gallium ■ Aluminum ■ Idium ■ arsenic ○ Solid rods of garnet crystal grown with ■ Yttrium ■ Aluminum ■ Scandium ■ Gallium ● Elements then added via doping ○ Chromium ○ Neodymium ○ Erbium

Laser Operation: There are 2 basic emission modes 1. Continuous wave - constant emission of energy a. Carbon dioxide and diode lasers b. Clinician might need to “stop” intermittently to allow tissue cooling c. Usually “gated” or “superpulsed” - minimizes thermal damage 2. Free-running pulse - true pulses of energy emanate from the instrument a. Solid state semiconductor lasers Laser Tissue Interaction ● Goal is to optimize various photobiological effects ● Photobiological effects = hemostasis, disinfection, biostimulation, rapid wound healing,

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pain relief, collagen growth, anti-inflammatory effect Power density + duration of exposure + amount of cooling + wavelength + emission mode+tissue characteristics = biological effect Lasers interact with dental tissues in one of four ways, depending on the tissue: ○ Transmission – laser energy directly through the tissue ○ Reflection – no effect on the target tissue ○ Scattering – results in decrease of energy. Sometimes useful, not always* ○ Absorption – primary and beneficial effect of laser energy

Lasers Available in Dentistry ● Wavelengths of lasers in perio treatment range from 650-10,600mm ● Components slide discussed earlier translates into the following: ○ Semiconductor diode lasers ○ Solid state lasers (Nd:YAG, Nd:YAP, Er:YAG, Er,Cr:YSGG) ○ Gas lasers (CO2)

Hard Tissues ● ● ●

Hydroxyapatite, collagen Used for cutting bone High wavelength

Hard and Soft ● ●

Can penetrate both. Limited hemostatic ability

Soft Tissues ● ● ● ●

Water, hemoglobin. Vaporize intracellular water Used for cutting soft tissue Lower wavelength

Uses ● All lasers used in dentistry have their own features, advantages and drawbacks ● There is still no one perfect laser for all treatment plans ● Laser practitioner must use the instrument in accordance with their clinical experience and scope of practice → education is vital! ● All lasers provide a useful addition to the dental armamentarium ● Really low level laser therapy (LLLT) can be used for most dental procedures (630900mm laser beam) Application for the dentist ● Caries removal ● Caries detection ● Tooth preparation ● Osseous surgery ● Endodontics ● Soft tissue surgeries (gingivectomy, frenectomy etc.) ● Sealants ● Whitening

Applications for the RDH ● Periodontal therapy ● Whitening ● Sealants ● Soft tissue lesions Lasers for non-surgical periodontal therapy ● Pocket debridement - little evidence ● Reduction of subgingival bacterial load - research inconsistent ● Scaling and root planing ○ Erbium lasers show most potential ○ Potential for damage ○ Research inconsistent ● Technique ○ For calculus removal ■ Used similarly to Cavitron ■ Parallel to LA of tooth ■ 45 degree angulation ■ Horizontal + vertical strokes ■ Water spray used ○ For pocket sterilization ■ Parallel o LA of tooth, same strokes as above ■ Difference: angled toward tissue ■ Debridement, followed by laser 1mm less than pocket depth ■ 3-45 seconds in pocket, dependent on depth of pocket ● Nd:YAG, Nd, YAP lasers also popular ● Periolase uses Nd:YAG laser → FDA approved ○ Patented procedure called LANAP (laser assisted new attachment procedure) ○ Cementum, bone, PDL regeneration Laser Safety ● Potential to cause harm to eyes and skin ● Matte finished instruments ● All PPE necessary ● High speed evacuation - for tissue “plume” + water ● Appropriate signage - OHSA ● Laser safety officer Reported Advantages ● ● ●

Client compliance - an easy sell Less bleeding Less irritation

Contraindications ● ●

The worst result with laser therapy is “nothing happens” Occasional mild discomfort/ache post

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Less pain post op Less tissue damage/swelling Tissue regen Anesthetization not always necessary Sterilization of treatment area Biostimulatory effects Many lasers FDA approved, but NOT endorsed as a way to do SRP

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treatment Be aware of presence of malignancies Thyroid gland Radiation therapy patients Pregnant women - precautionary Steroids laser therapy ineffective NOT to be used on healthy sites

↑↑↑↑↑ Scientific Approach to the Advantages ● Light increases metabolic rate of cells with compromised metabolism ○ Stimulate blood flow, macrophages, fibroblasts, osteoblasts ○ Reduces pain receptors ● Reduces oxidative stress ● Increases ATP ○ Displaces nitric oxide from final stage of cellular respiration cycle

Communication ● As with all therapies, informed consent is vital ● Risk and benefits must be discussed ● Clear outcomes of therapy must be revealed ● Evidence based information given What does research say? ● For scaling and root planing ○ An abundance of studies ○ Some very positive, but? ○ Some state calculus removal ○ Adjunct to SRP - key word! ● For wound healing, endodontics ○ Not well supported, anecdotal ● For caries ○ Better research, but still exercise caution Future Research ● Actively conducted for new wavelengths and applications ● Selective calculus and carious lesion ablation ● Evaluation of hard and soft tissues ● Hardening of enaml for caries resistance...