Conservative Dentistry And Endodontics

LASERS

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LASER: Light Amplification by Stimulated Emission of Radiation .Laser dentistry is easier, more precise ,less traumatic for patients . Lasers provide a state-of-the-art approach for modern dentistry.

DISCOVERY : It was discovered by Shallow and Towns on 1958. First working laser was built by Maiman of Hughes research laboratory in 1960.

COMPONENTS OF LASER :

  1. OPTICAL CAVITY : This is an internally polished tube occupying the center of the device .
  2. ACTIVE MEDIUM : This consists of chemicals that fill the core of the optical cavity . When stimulates , the active medium emits laser light . The active medium may be gas , crystals, solid state semiconductors.
  3. EXCITATION SOURCE : This surrounds the optical cavity and provides energy for exciting the active medium . This may be a flash light , arc light or an electromagnetic light .
  4. OPTICAL RESONATOR: This consists of two parallel mirrors placed at each end of the optical cavity .It amplifies the laser beam.
  5. COOLING UNIT : To dissipate the heat air or water -resistance coaxial coolants are provided in the unit.
  6. DELIVERY SYSTEM : The laser light is delivered by a quartz , fiber-optic , a flexible hollow wave guide or a hand piece.
  7. CONTROL PANEL : This provides control over the power output.

BASIC PRINCIPLES OF LASERS

  1. LIGHT : Light is a form of electromagnetic energy that exits as a particle , traverse like a wave , at a constant velocity . Laser light is monochromatic , coherent and collimated.
  2. AMPLIFICATION : This process occurs inside the optical cavity , where the photons released by the stimulated active medium are amplified by the optical resonator to produce the laser beam .
  3. STIMULATED EMISSION: Occurs in active medium due to excitation source . The photons energize more atoms which further causes emission of additional atoms .
  4. RADIATION : The light waves produced by the laser are a specific form of radiation of electromagnetic wave . All dental lasers emit visible light wavelength or an invisible infrared light wavelength in the portion of non ionizing spectrum called thermal radiation.
  5. LASER EMISSION MODES: They are two basic modes of laser emission , continuous wave emission and free running pulse emission.

LASER TISSUE INTERACTION :

  1. Reflection
  2. Transmission
  3. Scattering
  4. Absorption

TYPES OF LASERS :

1.BASED ON WAVELENGTH :

  • Argon lasers
  • Diode lasers
  • Nd:YAG lasers
  • Er,Cr: YSGG
  • Er :YAG
  • CO2 lasers

2. BASED ON TARGET TISSUE

  • Soft tissue laser
  • Hard tissue laser

LASER APPLICATION IN CONSERVATIVE DENTISTRY :

  1. CARIES DETECTION : This is achieved by using quantitative , laser induced fluorescence . Natural teeth show green florescence whereas carious shows red fluorescence and thus enables detection.
  2. CARIES PREVENTION : Argon lasers alter the characteristics of enamel to make it more resistant to caries without endangering the pulp. Lasers make enamel more acid resistant and increase its fluoride uptake when topical fluorides are applied.
  3. CAVITY PREPARATION USING LASERS : Hard tissue lasers are used for cavity preparation . The laser light vaporizes the water present in the enamel and thee dentin and causes micro explosion of the hydroxyapatite. This create micro craters on the tooth surface.
  4. DISINFECTION OF PREPARED CAVITY : Lasers can be used for the photo-activated disinfection of prepared cavities to destroy any residual microorganisms. This employs a solution of tolonium . chloride along with red light lasers . This combination releases nascent oxygen that can destroy the bacterial cell walls .
  5. LASER ETCHING OF ENAMEL AND DENTIN : Lasers produce a chalky white , rough surface of enamel that increases the retention of composite resin restorations .
  6. LASER CURING OF COMPOSITE RESINS : Argon lasers emit blue light which is suitable for curing composite restorations.
  7. GINGIVAL TISSUE MANAGEMENT : CO2 lasers , Nd:YAG , argon lasers are used for soft tissue surgery. Diode lasers are used for the retraction of tissues during the restorative procedures .or for re contouring the gingiva during smile design procedures.

REFERENCES: STURDEVANTS 7TH EDITION

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