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Lasers in Aesthetic Dentistry

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					 The University of Manchester
 School of Physics and Astronomy
 MSc in Photon Science




Lasers in Aesthetic Dentistry

Name:   Konstantinos Saroglou

              Laser Technology
                      April 2007
                   Manchester, UK
                  Aesthetic Dentistry (1)
     Smile Enhancement
1. The placement of the anterior teeth upon the upper lip
2. Transverse smile dimensions
3. Smile arc characteristics
4. The relationship between the gingival margins
                  Aesthetic Dentistry (2)
   The desirable characteristics of a
    perfect smile are:
1. Tooth dimension, proportionality and color
2. Contacts and Embrasures
3. Gingival esthetics




    Gingival                   Gingival
      Shape                     Contour
                     Historical Review
   The desire to use lasers in dentistry has been there since 1962
   First real application of lasers in dentistry was achieved by the
    introduction of CO2 lasers
   During the 1980’s CO2 lasers, where used for soft tissue surgery in
    the oral cavity
   Hard tissue lasers promised the gradual replacement of the
    mechanical drill
   CO2, Nd:YAG and mostly Er:YAG lasers can be used for hard tissue
    applications
   In aesthetic dentistry soft tissue lasers are mostly used
                         Why lasers?
   The precision of cutting is much greater
   Many lasers can achieve sterilization while cutting
   The visibility of the cut increases
   Postoperative complications such as pain or infections are minimized
   The minimized wound contraction leads to the avoidance of scars
   Adjacent tissues remain unaffected
   The operation can be completed in one session
   Both patient and doctor can be benefited
                 Types of Lasers [CO2]
   CO2 Laser operates mainly at 10.6μm
   They are used for vaporizing, cutting, gingivoplasties,
    gingivectomies and biopsies
   It must be incorporated with a visible laser beam for aiming (usually
    a He-Ne laser)
   Several limitations prohibit the use of this laser for hard tissue
    operations
   There is no contact with the tissue during operation thus no tactile
    feedback can be achieved during the operation
   There is a time delay between the realization of the incision and the
    ability to see the cut
        Types of Lasers [Diode Lasers]
   Surgical diode lasers operate mainly at two wavelengths, 812nm by
    AlGaAs and 980nm by InGaAs
   Energy absorbed mainly by melanin
   They can be used for rapid cutting, vaporizing, and bacterial
    reduction
   They operate at contact mode hence feedback is accessible
   Laser energy at these wavelengths is absorbed by pigmentation in
    the soft tissue thus making them excellent haemostatic agents
   They can be used without anesthesia
        Types of Lasers [Erbium family]
   Er:YAG operates at 2940nm and Er:YScGaG at 2790nm
   Energy is absorbed by collagen, hydroxiapatite, and water
    components
   Can be used in contact and non-contact mode
   In non-contact the cut is scalpel-like with little hemostasis
   In contact mode hemostasis is adequate
   Most important it can be used for hard tissue operations
        Types of Lasers [Argon lasers]
 Low power Argon lasers which
  operate at 514nm are used
 Cutting, vaporizing, hemostasis
  and cure of composite restorations
  can be achieved
 The energy is absorbed mainly by
  hemoglobin
 They operate at contact or non-
  contact mode
       Types of Lasers [Nd:YAG lasers]
   They operate mainly at
    1064nm for dental
    applications
   They have the same
    use as Argon and diode
    lasers
            Theoretical Background (1)
   Soft tissue laser or hard tissue laser depend their function on the
    absorption of the laser energy by certain components of biological
    cells
   Absorption depends on the laser wavelength, the power of the
    beam and the proportion of the component within the cell
   The cells are ruptured when the absorption of the laser energy
    virtually boils their interior
   If the wavelength coincides with the absorption band of certain
    components of blood hemostasis is achieved.
           Theoretical Background (2)
    Soft tissues are subjected successively to the following
1.   Warming
2.   Welding
3.   Coagulation
4.   Protein denaturization
5.   Drying
6.   Vaporization
7.   Carbonization
           Theoretical Background (3)
    Hard tissue removal depends on explosive ablation processes
    Several techniques have been developed such as:
1.   Evaporation, used with low peak power (or cw lasers)
2.   Explosive tissue removal, which is the most efficient process
     (mainly used with Er lasers)
3.   Plasma mediated ablation, which is a problem since when plasma
     develops, at certain densities it can act as a perfect reflecting
     shield, protecting the target from laser radiation. IR lasers suffer
     more from this problem
4.   The use of UV laser radiation can lead to both photochemical and
     photothermal ablation due to the strong absorption from the
     organic constituents of the tooth
     Parameters of the Laser System (1)
    Pulsewidth
    There are three major groups of pulsewidth:
1.   From femptoseconds to picoseconds
     At this pulsewidth magnitude plasma formation in the surface
     occurs, leading to the blow off of the surface layer
2.   Nanoseconds
     In this regime mechanical side effect such as acoustic or shock
     waves may appear. Likewise the formation of plasma may
     decrease the efficiency of each pulse
3.   Microseconds
     Due to the length of the pulse thermal heat is carried towards the
     pulp, endangering the overall health of the tooth
    Parameters of the Laser System (2)
   Wavelength

      Wavelength               Absorption by
       < 320nm        Aromatic amino and nucleic acids
     320nm – 3μm   Low absorption in healthy enamel and
                   dentin, high absorption by bacteria and
                                    caries
      3μm – 10μm           At 3μm and at 6μm water
                   At 6.2μm – 6.6μm Amide of the proteins
                       At Phosphate at 9.1μm – 10.0μm
                 Dental laser systems
    The actual laser system should:
1.   Offer pulsewidth and output power control
2.   Be equipped with external test and
     calibration guarantee equipment
3.   Use fibre optics to produce an easy to
     handle and safe delivery system
4.   Use an aiming beam if an invisible
     wavelength is used
5.   Deliver a small waist of the output beam
6.   Offer small dimensions and as little weight
     as possible
Thank you for your attention
                           References
   Rudolf Steiner, “New laser technology and future applications”,
    medical laser application, Vol.21, p.p. 131-140, 2006
   Harvey Wigdor, “Lasers in Dentistry”, Ravenswood Hospital Medical
    center
   Thomas Henning & Peter Rechmann, “Basics of the application of
    pulsed lasers in dentistry”, SPIE, Vol.2922, p.p.64
   Timothy C. Adams & Peter K. Pang, “Lasers in aesthetic dentistry”,
    The Dental Clinics of North America, p.p. 833 – 860, 2004
   V. Wieger, A.Yousif, M. Strassl, E.Wintner, “Ultra-short laser pulses
    in dentistry”, SPIE, Vol. 6344, 2005
   David M. Sarver & Mark Yanosky, “Principles of cosmetic dentistry in
    orthodontics Part 1,2 & 3, The American Association of
    Orthodontics, 2005
   Ehud Ben-Hur & Ionel Rosenthal, “Photomedicine Vol.III”, CRC
    Press, 1987

				
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