LASERS IN CONTENTS

• Introduction • Fundamentals • History • Laser • Working of laser • Advantages & disadvantages • Tissue response to lasers • Lasers in dentistry • Hazards of lasers • conclusion introduction

• LASER is an acronym , which stands for Light Amplification By Stimulated Emission Of Radiation • Device that converts electrical/chemical energy into light energy • device that creates a uniform and coherent light that is very different from an ordinary light bulb • Also can be described as a device for generating a high-intensity, parallel beam of monochromatic(single wavelength) electromagnetic radiation. • Laser light can be focused down to a tiny spot as small as a single wavelength. Fundamentals of lasers

• Light • Amplification by the • Stimulated • Emission of • Radiation HISTORY

• 1960-first laser • 1993 Nd:YAG Laser • 1993 Kinetic Cavity Preparation • 1994 CO2 Laser, Argon Laser • 1996 Laser welder • 1997 Nd:YAP Laser • 1998 Er:YAG Laser Light

Form of electromagnetic energy Properties of laser : • Monochromatic • Collimation • Coherency • intense • Monochromatic-Characterized by radiation in which all waves are of same frequency and wavelength. • Collimated: all the emitted waves are parallel and the beam show very low divergence. This property is important for good transmission through delivery systems. • Coherency: indicating that the light waves produced by a laser have a specific form of electromagnetic energy which are in phase with one another. • Intense in nature • A- Amplification • means that a very bright intense beam of light can be created. • The laser may be activated by a few photons which then act to produce many more, and the initial light generated is computed to make a very bright compact beam • S – Stimulated E-Emission • If an atom in the excited state is struck by a photon of identical energy as the photon to be emitted, the emission could be stimulated to occur earlier than would occur spontaneously. This stimulated interaction causes two photons that are identical in frequency and wavelength to leave the atom. THE LASER

• Basic components.. • An ACTIVE LASING MEDIUM :- - can be a solid, liquid or gas • Enclosed within a LASER CAVITY bounded by two perfectly parallel reflectors(mirrors) • PUMP SOURCE – high energy radiation pumped into the active medium POPULATION INVERSION :- • condition when energy from pump source is absorbed by active medium until the majority of atoms, ions or molecules are raised to their upper energy state. • this condition is NECESSARY to generate laser light • TWO PARALLEL REFLECTORS – situated at end of laser cavity act to focus light along within the axis of cavity. • So light is repeatedly bounced b/w the reflectors • One of the mirrors is only partially reflective, enabling some of the light to escape the cavity as a beam of laser light • Process of supplying energy for amplification- pumping

Laser interaction with biologic tissues • Four different interaction : Reflection Scatter Absorption Transmission • Reflection:the laser reflecting or redirecting itself away from the tissue surface & having no effect on the target tissue • Absorption: this depends on the tissue charecteristics like water content & the level of pigmentation & on laser wavelength and emission mode • Transmission:the tissue transmits the laser energy through the tissue ,with no effect on the target tissue • Scattering: this process will weaken the energy of thebeam & produces no useful biological effect. Causes heat transfer to adjacsent tissue& thermal damage. ADVANTAGES OF LASER

• Processing of matter without contact. • High working speed • Outstanding precision BENEFITS

• Soft, • quiet, • vibration-free operation • As fast as the high-speed turbine • CO2 laser cuts and coagulates soft tissue without bleeding • No risk of cross-infection • Sterilization of operating field • Fewer cracks than with turbine • Multiple quadrant dentistry • No need for etching • Pulsing minimizes charring and thermal necrosis LASER IN DENTISTRY

• Lasers are still in the pioneering stage, but there are many current uses There are three types of Dental lasers: • Surgical Laser (soft tissue) • Curing Laser • Tooth Laser (hard tissue SURGICAL LASER

• This laser replaces traditional surgery for many gum and soft tissue dental applications and is gentler than traditional surgical procedures. This laser used for : • Improve treatment results for gum disease • Contour gums for smile enhancement • Surgically correct oral abnormalities • Surgically assist in arresting herpes lesions and canker sores • Assist in biopsies • Treat infant tongue/frenum problems which can hinder proper chewing/sucking • Treat child/adult frenum problems which can cause speech impediments, gum disease, and teeth to grow apart rather than together Curing laser

• This laser spectrum light source is used for rapid teeth whitening and placing all tooth- colored restorations (fillings) and repair procedures. • Bonds created by this advanced instrument result in dentistry that is twice as strong • The light source increases gradually during the curing process to create the best bond available in dentistry today. • Appointment length is also reduced because it is 500% more powerful than standard equipment. • Less than 1% of dental offices nationwide have this instrument, making it one of the newest tools in dentistry. • TOOTH LASER (hard tissue) Third type of laser is used to remove cavities. But since this laser cannot be used on existing metal fillings, we use micro dentistry. • MICRO DENTISTRY one of the greatest advancements in the field of dentistry. offers the ultimate flexibility and capability. It is also the most tooth conservative dentistry available • About 50% of cavities are candidates for this technique and there is no drilling, no needle, no extra fee, and no pain • And because this process is so efficient, it reduces appointment length Hard tissue application

• Desensitize exposed root surfaces • Diagnosis of non-cavitated caries • To arrest demineralization and promote remineralization of enamel. • Debond ceramic orthodontic brackets DIAGNOdent caries detector

• can find cavities that other dental instruments can miss. • is designed as an adjunct to a traditional oral examination in the detection of occlusal decay. • Teeth that are suspicious for caries can be surveyed with the device

• Treatment of dentin hypersensitivity. • In bleaching • Adhesion of pit & fissure sealant • Most obvious application – controlled removal of dental enamel, dentin, bone or cementum. • Replacement of dental drill is a real possibility for the future Lasers used in dentistry

• Nd:YAG • Diode • Co2 laser • Er:YAG • Er,Cr:YSGG • Argon Nd:YAG laser

• Solid active medium containing crystal of yttrium-aluminium-garnet doped in neodymium • Wavelength :1064nm (invisible beam in infrared range) • 1st laser designed exclusively for dentistry • Fibereptically derived in a pulsed mode & is most often used in contact with the tissue • The pulsed Nd:YAG laser is ideal for soft tissue procedures & rootcanal sterlization • Nd: YAG laser DIODE LASER

• Solid semiconductor laser that uses a combination of aluminium,galium,arsenide that converts electrical energy to light energy • Wavelegth:800-980nm • Fiberoptically derived in continuous or in pulsed mode & used in contact with soft tissue • Pooorly absorbed by tooth structure ,hence,soft tissue surgery can be safely performed • Welll absorbed by pigmented tissue • Advantage being- compact,portable & ecnomical advantages

• Portable • No special power • Sulcular • No cooling debridement connection • Root canal • No heat treatment • Quiet Affordable • More powerful, • less traumatic Co2 laser

• Gas active medium laser • Wavelength :10,600nm • Derived through hollow tube via handpiece & cannot be delivered by fiberoptics • Not suitable for hard tissues • Ideal laser for soft tissues, especially for cutting dense fibrous tissue Co2 gas as lasig /active medium • Delivery system – uses an articulated arm (a series of hollow tubes connected together through a series of six to eight articulating mirrors). Er:YAG

• Er:YAG is a solid active medium crystal containing yytrium,aluminium,garnet that is doped with erbium • Wavelength: • Er:YAG-2940 • Delivered through a fiberoptic system in a pulsed modeThe Er:YAG laser can be used to disinfect cavity prep , in case of residual bacteria contaminating, otherwise intact enamel or dentin, or in fissures prior to sealing Application of laser in • Vascular vitality asssessment of pulp • Pulp capping & pulpottomy • Sterilisation of rootcanals • Obturation • Apical surgery Cavity preparation

• Efect of ruby laser radiation on enamel – Goldman, Stern & Sognnaes, 1964 • Carbondioxide laser- Lobene et all 1968 • Nd:YAG laser – Yamamoto & Ooya 1974 • Argon laser – Goodman & Kaufmann 1977 • In removal of enamel n dentin – thermal side effect occoured. • Superpulsed carbon dioxide laser – removal of dentin without thermal side effect possible. • Transversal stimulation or carbon dioxide TEA (the Alexandrit laser with double frequency) – most efficent carb.dioxide laser for dental hard tissue ablation. • Drying the surface with laser is very quick , efficient and gentle. • Erbium laser has bactericidal abilities. • Because high surface temperature can be achieved for a short time by irradiation. • Irridation of caries by a sequence of laser pulses leads to consecutive dessication and sterilization. • Dentin hypersensitivity

• Best results obtained whn affected areas exposed to co2 , Nd:YAG, Er:YAG, Diode laser radiation • Colojoara et al showed that dentin hypersensitivity can be reduced without any damages to pulp vitality by using co2 laser. • They also showed that when using co2 laser , in parallel direction with dentin tubules, the desensiting effect ws obvious aftr three exposures. curing

• The first materials introduced in 1970’s (photopolymerised composites) wr cured by ultraviolet light. • Power et al showed that an argon laser requires shorter curing times & the materials dentin bond strength was stronger when compared with laser • Variables that control the depth &extent of cure include - time of exposure - composite material - wavelength - intensity of light - particle size of filler • current reserches report that used at the power of 250 +/- 50 mW for 10sec per increment , • the argon laser provides good curing of light activated restorative material in shorter period of time with equal or better physical properties than the conventional halogen curing light laser teeth whitening(bleaching) • With todays technology, laser teeth whitening through the use of the Diode Laser is the quickest and most dramatic way to brighten your smile if porcelain laminates are not an option. • All procedures use hydrogen peroxide or carbamide peroxide to bleach out stains on your tooth enamel, but this is where the similarity ends when comparing standard bleaching procedures such as whitening performed with a light cure to laser whitening. • Laser whitening is superior to all other whitening techniques since 1.laser whitening products contain the highest concentration of peroxide 2.the laser provides the highest light intensity available 3.the procedure is done in the office at chairside • thus allowing us to concentrate in those areas of your mouth where the type and location of discoloration is worse. Laser technology allows us to whiten your teeth with amazing results in just one hour! Whitening techniques will vary with every individual depending on: • 1.the type of stain on your teeth • 2.where the stain is located • 3.the amount of time the whitening gel is used • 4.the peroxide concentration in the whitening gel • 5.the intensity of the light activating the whitening gel • In Laser-Assisted Tooth Whitening, the laser enhances the effect of bleaching agents for faster, more comfortable and more effective results. • By stimulating the bleaching gel to react faster, the bleaching agent (mainly peroxide) spends less time on the tooth. • This leads to increased comfort levels BLEACHING APPLICATIONS -GENERAL

• Eye surgery • Cancer treatment • Removal of tattoos • Cosmetic surgery • Hair removal • Cold Sores • Nerve Regeneration • Removal of old restoration-gold, ceramic • Root canal therapy • Temporomandibular Joint Treatment: reduce pain and inflammation Crown lengthening Soft tissues

• Frenectomy Tongue tie Incisional and excisional biopsies

• Inflammatory papillary hyperplasia Aphthous ulcer Operculectomy Removal of hyperkeratotic lesions Removal of malignant lesions Soft tissue crown lengthening Vestibuloplasty Removal of granulation tissue Removal of vascular lesions- Hemangioma Pyogenic granuloma Implants – Stage II – at the time of recovery Laser Gingivectomy

• A Gingivectomy is a periodontal surgery that removes and reforms diseased gum tissue or other gingival buildup • Performed in a dentists office, the surgery is primarily done one quadrant of the mouth at a time under local anesthetic. • CO2 laser with wavelength of 10,600nm GINGIVECTOMY FRENECTOMY Hazards of laser

Types of hazards • Ocular hazards # injury to eye – direct emission or by reflection from mirror like surface. # irreversible retinal burns- by conversion of incident radiation to heat energy Tissue damage

• damage to skin & other non-target tissue result from thermal interaction of energy with tissue proteins • temperature elevations can produce denaturation of cellular enzymes &structural proteins which interrupt basic metabolic processes Environmental hazards

• Are referred to as non-beam hazards • Capable of producing smoke , toxic gases and chemicals. • Laser plume – composed of vaporised water (steam), carbon particles, cellular products Mechanical effects

• High energetic & short pulsed laser light lead to a fast heating of dental tissue. • Energy dissipates explosively in vol of expansion – accompanied by fast shockwaves.. • The shockwaves lead to high pressure – destroy or damage adjacent tissue Electrical hazards

• Can be in form of - electric shock - fire - explosion • LASER HAZARD CONTROL MEASURESThe small flexible fiber optic , hand pieces or tipmust be steam sterilized in sterilizing pouchesUse of protective wearUse of screen & curtains should be promoted Combustion hazards

• Flammable solids , liquids, gases used within the surgical setting can be easily ignited if exposed to laser beam. thermal effects of laser irradiation

• Temperature < 60 celcius ~ tissue hyperthermia ~ enzymatic changes ~ edema • Temperature > 60 celcius ~ protein denaturation • Temperature < 100 celcius ! Tissue dehydration ! Blanching of tissue • Temperature > 100 celcius ! Super heating ! Tissue ablation&shrinkage