education dental

1. ELECTROSURGERY & LASERS
in
Esthetic Dentistry

2. LASER
• Light
 Monochromacity
 Collimation
 Coherency
 Efficiency
 Wavelength – delivery and tissue interaction

3. LASER
• Amplification
 Increases the intensity of beam - mirrors
 Optical cavity – centre – core - active medium – elements
• Stimulated emission
 Smallest unit of energy (quanta) – absorbed – molecule –
brief excitation – spontaneous emission
 Additional quantum of energy – same excitation energy -
field of excited atom –– stimulated emission – just before
• Radiation
 Light waves – electromagnetic energy
 All dental lasers – 500-10,600 nm
 Visible or invisible infrared nonionising
 Emit thermal radiation

4. LASERS USED IN DENTISTRY
Type source Wavelength (nm)
Infrared Carbon dioxide 10,600
Er, Cr:YSGG 2780
Er:YAG 2940
Ho:YAG 2060
Nd:YAG 1064
Diode 812,980
Visible HeNe 633
KTP 532
Argon 514, 488
UV excimer XeF 351
XeCl 308
Kr F 248
ArF 193

5. LASER DELIVERY SYSTEMS
• A flexible hollow wave guide
• Glass fibre optic

6. • Lasers – short WL – Ar, diode and Nd:YAG – glass fibre
optics
• Er – challenges - fiber manufacturing - WL large –
donot fit into –crystalline molecules of conducting
glass
• Carbon dioxide laser – largest WL- beyond
transmission – fibre optics – conducted in hollow tube

7. LASER EMISSION MODES
• Continuous wave – beam is directed – one power – as
long as the foot control –depressed
• Gated pulse mode – periodic alterations of laser –
opening and closing the shutter - cw mode
• Superpulse mode – significantly shorten pulse
duration –less than 50ms
• True pulsed/free running pulsed – large peak energies
– laser light – emitted for a short span –ms – relatively
long time – laser is off
 Pulsed mode – target tissue has time – to cool –
berfore the next pulse - is emitted
 CW- operation – cease – emission manually – for
thermal relaxation - to occur

8. LASER ENERGY & TISSUE TEMP.
• Principal effect - Photothermal
• Effect – temperutre rise & reaction of interstitial and
intracellular water
• Rate of temp rise – cooling & heat dissipation – tissues
• Irradiation parameter – critical - mode, power & time
TISSUE TEMP
(DEG C)
OBSERVED EFFECT
37-50 hyperthermia
60-70 Coagulation, ptn. denaturation
70-80 welding
100-150 Vaporisation, ablation,
spallation
>200 carbonisation

9. LASER- TISSUE INTERACTION
• Absorption
• Reflection
• Transmission
• Scattering
• Depends – optical properties – target tissue –
some degree - relative

10. Absorption
• First and most desired intention
• Amount of energy absorbed – tissue characteristics –
pigmentation, water content - laser wavelength and
emission mode
• Tissue compounds – chromophores –absornb certain WL
• Arterial blood – reflects - red WL – strongly absorbs – blue
and green WL
• Venous blood – absorbs more red light – appears darker
• Melanin – strongly absorbed - shorter WL
• Water – varying degrees – absorption – dep. WL
• Tissue fluids – readily absorb – CO2, Er at outer surface

11. • Argon – highly attenuated – Hb
• Diode and Nd: YAG – High affinity for melanin, less
interation with Hb
• Longer wavelengths – more interactive – water and HA
• Largest absorption peak of water – just below 3000nm –
Er:YAG
• Erbium – well absorbed - HA
• CO2 - well absorbed by water and greatest affinity for
tooth structure

12. Transmission
• Directly through the tissue – no effect on target
tissue
• Dependent on wavelength
• Water – relatively transparent – shorter wavelength,
argon, diode and Nd:YAG
• Erbium family – acts – mainly – surface – 0.01mm
• 800nm diodes – tissue depth – 100mm
• Diode and Nd:YAG lasers – transmitted thro’ lens,
iris, cornea & absorbed on retina

13. Reflection
• Beam redirecting itself off the surface - no effect on
target tissue
• Caries detecting laser device- measure the degree of
sound tooth structure
• Reflected light- narrow or diffuse beam
• More divergent- increase in ‘d’ bn. hand piece and
target tissue
• Adequate energy with ‘d’ over 3m
• Dangerous- unintentional target-
major safety concern

14. Scattering
• Weakening the intended energy
• No useful biologic effect
• Heat transfer- tissue adjacent- surgical site-
unwanted damage
• Useful
- curing a composite resin or
- covering a broad area

15. BLEACHING
• Contact time & concentration of hydrogen peroxide –
critical factors – effectiveness
• Light and heat – do not increase the lightening effect
- not necessary
• Lights- long wavelength – low energy photons – high
thermal energy – unfavourable effects

16. • Specific features – light energy - laser – add beneficial
effects – rate of chemical bleaching
• Unique property - absorbed by chromophores
• Emulsions can be added – bleaching gel – inducing,
promoting – fast, effective & safe redox reaction
(Wernisch & Moritz etal)

17. • Argon (514.5 nm), KTP (532 nm) and diode laser
• Shorter wavelength – Argon (514.5 nm), KTP (532 nm) –
high energy photons – less direct thermal characteristics –
safe – both vital & nonvital tooth structures – feasibility –
photobleaching
• Interesting facts - tetracycline staining:
• Tetracycline stains darken on exposure to sunlight
• (Tetracycline-hydroxyapatite – photo-oxidation – red
quinone product -AODTC)
• Further prolonged exposure – subsequent lightening
• (Continued photo oxidation - bleaches – red quinone)
• Efficient wavelengths – 290nm, 365nm (UV range), 532nm
(visible green light)
• KTP laser – added advantage – photochemical reaction

18. • Diluted hydrogen peroxide – capable –irreversible
bleaching – quinone
• Photochemical reaction (KTP) – higher intrinsic overall
radical yield with a higher rate - than - thermal activation
• Overall time required – reduced, improved efficiency
• Whitening effect (synergy effect) - greater then diode laser
- photothermal bleaching
• Decomposition of the staining agent
• Conjugated electron system (absorbing visible light) –
staining agent – partly broken down – react – oxidising
agent radicals – further break down
• Radicals – molecular structure, stabilised – no longer
reactive - substantially free – conjugated electrons –
absorbing visible light – will now reflect white light

19. • KTP laser – modest & gradual temperature change –
efficient heating of surface gel
• Diode lasers – greatest thermal changes – level of dental
pulp – rapid temperature rise in first 30 s – limited heating
of surface gel, 4 deg C
• Factors – Temperature changes - thermal effects – tooth:
• Laser – outside UV range, near IR and IR - minimses- risk
• Degree of attenuation of the beam
• Initial intensity
• Irradation time
• Tooth thickness
• Absorption properties – gel – surface & intrapulpal effect
(Optimum ratio – 1:1 - (TiO2):gel, Thicker gel – handling)

20. • Clinical procedure:
• Guide lines - manufacturers – strictly – followed
• Cheek retractor – cotton mouth dry field system -
aspiration system
• Safety glasses
• Cleaning of teeth – airflow or pumice and water
• Polishing pastes – not to be used – contain oils – inhibit
laser energy & redox reaction
• Dry the teeth and gums – compressed air
• Apply the gingival dam (gingival margins, sulcus, cover the
cervix 1mm, exposed dentin spots, spots not to be
bleached, remove accidental spots) – polymerise
• Prepare the gel - mix 5ml of peroxide with powder –
viscosity – adjusted - changing the volume of peroxide

21. • Shake well before use
• Mix powder and liquid well – close the lid – rest for 5 min –
allow the pH to rise
• After removing the gel for each application – closed the lid
and seal well
• Gel - pH – 10 – after laser irradiation
• Apply the gel – brush – irradiate for 30 s
• Power setting 1W
• Energy densities – surface of the gel - can be decreased –
increasing the distance of the fibre tip from surface
• Unacceptable sensitivity occurs – decrease energy densities
or power setting
• Aspirate the gel thoroughly

22. • If accidental contact of the gel – soft tissue / skin occurs –
immediately apply a thick layer of Vit E gel –strong
antioxidant – stops irritaing and burning sensation almost
immediately
• Check the color - if necessary – redo the procedure
• 10 min – overall interaction time – before –sucking and
rinsing
• A max. of 4 – 10 min interaction – one treatment session
• Remove the gingival protection
• Apply the fluoride gel liberally
• Irradiate every tooth for 15 s
• Profound resistance to future acid attacks
• Remove cheek retractor, cotton rolls, safety glasses

23. • Instruct the patient - maintanance gel
• Appointment for control session – after 2 weeks & one
after 6 months

24. Argon laser
 Primarily absorbed by Hb
 Precision cutting, vaporising, hemostasis & coagulation
 Curing of composites
 Transillumination of teeth

25. CO2 laser
 Vaporisation, cutting, coagulation
 Gross debulikng, frenectomies, gingivoplasties,
gingivectomies and biopsies
 Not suitable for bone and tooth structure cutting

26. Diode lasers
 Al-Ga-As (800 nm)
 In-Ga-As (980 nm)
 Contact mode for cutting, vaporisation and bacterial
reduction in tissue adjacent to tooth structure
 Noncontact mode for deeper coagulation

27. Erbium lasers
 Absorbed by collagen, hydroxyapatite and water – cuts,
soft tissue tooth and bone
 Er-YAG (2940 nm)
 ErCr-YSGG (2790 nm)
 Non contact mode – cuts like scalpel, little hemostasis
 Contact mode – soft tissue sculpting with adequate
hemostasis
 Poor hemostasis

28. Advantages of lasers
 Hemostasis (increases platelet activation)
 A reduction in the bacterial population
 Less need for suturing
 Faster healing
 Less postoperative pain
 Less postoperative swelling (sealing of lymphatics)
 http://www.youtube.com/watch?feature=player
_detailpage&v=xNpcJf-fSnE