July 18, 2014


There are many different types of lasers. Two of the most popular are the diode and the erbium laser.

Surgical Diode lasers

  • Wavelength of between 810-980 nm – outside the visible spectrum.
  • Consists of a semiconductor chip, which is relatively inexpensive and has many useful clinical applications.
  • Optical window – as laser energy enters tissue it is poorly absorbed – the optical window in tissue is present due to reduced absorption of infra-red wavelengths by tissue chromophores. Optical window can lead to deep tissue effects that can be beneficial but there is also the potential for deep tissue harm.
  • Optical hazards – eye damage. Corneal scar, which is reparable. Alternatively, red and near infrared wavelengths can pass straight through the cornea to the back of fovea, which causes it to burn out. Nominal hazard distance of diode up to 4.5 m. Number of incidents of harm virtually nil but we do need to be careful as this can be a major source of litigation. In contrast, the erbium laser is superficially absorbed so this can cause a corneal scar but the hazard distance is 5 cm so this is very unlikely. Therefore you definitely need good optical protection for diodes but this is not as crucial for erbium lasers although optical protection is still mandatory. L4/5 level of protection required. Can also get a protective film built into loupes or filters for microscopes. Even with glasses, don’t look directly into the beam.
  • Safety also includes high volume evacuation and high filtration mask (due to ablation plume). Use the lowest power necessary.
  • Surgical laser 1 watt output focused on a diameter of 0.1 mm gives a power density of 10 000 W/cm2. Precise tool to deliver intense photonic activity without collateral damage.
  • Tissue composition – soft tissues are 85% water, blood components 14%, haemoglobin is around 35% of blood, perfusion of tissues 1-5%.
  • The diode likes colour and converts it to heat. Chromophore selectively absorbed by laser is coloured protein, melanin and haemoglobin.
  • Different consistency of tissue scatters and can have big optical footprint from small point source – useful but higher settings can be hazardous. Biolase tip diameter 200-400 micron – small footprint and useful for surgery. Others e.g. 2.8 cmlarger area – large footprint – lower dose and used for low level laser therapy and biomodulation.
  • Forward scatter may increase dose at depth. 4.2 J increases water temperature by 1 degree centigrade. Depending on heat can produce a range of responses – warming, coagulation, vapourisation, carbonisation.
  • Beam is not flat – centre of the beam has double the amount of energy than the sides. Important when thinking about dose. All delivery handpiece have a Gaussian beam. One tool with wide range of effects, provided we know dose.
  • Effect of divergence – typical beam divergence is 8 degrees, at 1 mm away: 50%, 2 mm away 37%, 3 mm away 22%. Take advantage of the distance to increase or decrease the dose to the tissues.
  • Selective absorption by wavelength by pigment – can reduce pigmentation.
  • Laser energy: joule (measure of energy), watt (unit of power), one watt = one joule for one second, power density (watts/cm2), smaller the focal spot the higher the power density, difference between 200 micron and 400 microns tip = x4.
  • Laser tissue interaction is a dose related event. Low level – photochemistry, higher then coagulation (helpful as stops bleeding), vaporization (helpful as fragment tissue without carbonizing), even higher causes photoablation and photodisruption.
  • Photo thermal reaction – hot poker – better than electrosurgery but still using heat.
  • Need carbon on the end of the laser to contain this heat.
  • Recommended settings for initiation – 0.3 watts/cm, repeat 6-8 times, maintain contact with articulating paper, re-initiate if necessary. 0.7-1.1 Watts will then be a good setting (lower energy, less collateral damage).
  • If the laser is not cutting properly it could be because the tissues are stuck to tip (clean with gauze) or the laser is not initiated properly.
  • Potential uses in regeneration therapies – Praveen Arany. 600-950 nm absorbed by cellular photoreceptor – wound healing, tissue repair, prevention of tissue death, relief of inflammation and oedema, reduction in neurogenic pain. Cytochrome c oxidase – production of ATP (energy but also intra and intercellular communication). Anti- inflammatory mediation, nociceptor mediation (inflammatory cytokines). Periodontal disease cytokine mediated. Many conditions are due to inflammation e.g. diabetes, Alzheimer’s – local and systemic effect – this is an area of research.
  • Mechanisms of low level light therapy suggested by Michael Hamblin. Effects all cellular groups – fibroblasts, macrophages, lymphocytes, epithelial cells.
  • Clinical applications of low level laser therapy – surgical wounds of oral tissues, extraction sites alveolitis, gingival incisions, recurrent aphthous stomatitis, oral mucositis as a result of cancer therapy, TMJ disorders, accelerating healing of damaged neural tissues, supportive treatment in BRONJ, osseointegration and bone regeneration, accelerated tooth movements in orthodontics. Therapeutic applications – progressive or immediate relief of pain, reduction in muscle tenderness and stiffness, improved functionality of the affected area.
  • EJ Choi. Biological effects of a semiconductor diode laser on human periodontal ligament fibroblasts. J Periodontal Implant Sci. 2010 Jun;40(3):105-10.

Erbium lasers

  • Wavelength of between 2.78-2.94 micrometers.
  • High affinity for water, activated water expands 1600x in 1/50th second, absorbed in 2-4 microns, cut soft and hard tissue with very little heat.
  • Water expands, creates shock wave, water contracts and as it does you get secondary cavitation which generates shear forces and lifts off biofilm & calculus. Explosive power plus cavitational effect.
  • Socket preservation – dual wavelength therapy – one laser for surgery and another to change inflammatory cascade. Enhance amount of bone in sockets. Erbium to debride, diode to disinfect in immediate vicinity of tip to kill chromic bacteria and scatter zone promote healing.
  • Other uses: photobiomodulatory (Kesler 2011), dentine hypersensitivity treatment and restorative applications.


  • Radially firing tips – lateral component 80% and therefore ideal for pockets.
  • Diode and Ng:YAG are used in Perio. Benefits controversial- conflicts in evidence base
  • Bactericidal effects – pigmented periodontal pathogens and non-pigmented periodontal bacteria.
  • Removal of epithelial lining and sulcus; controlled coagulation may improve visibility and access.
  • Smear layer removal in vitro (Nd YAG) but not appropriate in vivo due to temperature rise.
  • Photodynamic therapy (PDT)
  • Er:YAG, Er,Cr:YSGG: in Vitro studies assessing – bactericidal effect, removal of biofilm, removal of smear layer, removal of calculus, removal of endotoxin and infected cementum, no damage to root surface, adherence of blood components and fibroblasts, removal of epithelial lining and sulcus (controlled coagulation may improve visibility and access).
  • In vivo studies – very few clinical trials so far. Systematic reviews are difficult because of different laser wavelengths, settings, angles and tips.
  • Studies: Aoki 2004, Schwarz 2008, Kelbauskiene 2011, Sculean 2004, Dyer 2012, Pavone 2014.
  • Clinical studies – as effective if not better than scaling, less recession etc. Adjunct rather than an alternative
  • Periodontal regeneration – formation of new attachment, can happen spontaneously but unpredictable. The laser sets up an environment to help regeneration to occur spontaneously.
  • Photobiomodulation – stimulation of other cells and promoting healing, reduced post-op pain and sensitivity with dual wavelengths.
  • Other applications – tissue thinning, treatment of peri-implantitis.
  • Non-surgical takes more time. Surgery takes less time. Reduced need for surgery
  • Statutory and regulatory requirements: Controlled zone, team training with proof, laser protection advisor (LPA) and evidence of clinical protocols and adherence to guidelines.


  • Superficial lesion – up to 10 J for healing per cm, 20 J or more for analgesia/anti-inflammatory effect.
  • Can use a surgical or contour handpiece.
  • Deep – dose plus dose again for every 1cm. Slow sweeping motion
  • Anti-inflammatory 3 cm deep = 4 x time = 20 J /cm = 4 x 40 sec
  • For surgical ensure you initiate the tip – carbon on tip.
  • Continuous wave – on all the time. There are other patterns including super pulse.
  • Nurse should blow the 3 in 1 air on the tissues to keep them cool.
  • Can pre-cool with cold pack if dense tissues then dry slightly to prevent reflective energy.
  • End cutting tool – cuts from end and down – 1.2 W if fast cut in continuous wave but may get carbonisation – okay for bulk reduction but not in the aesthetic zone.
  • Every 15 seconds look at and clean the tip.
  • Wiping will not remove initiation. Only removed if burnt off.


  • Aiming beam – check that it is bright and concentric.
  • Erbium crystal with flashing bulb – free running pulsed laser.
  • Peak power can be 100 kW.
  • 10-50 pulses per second.
  • Can cut through hard and soft tissue.
  • Mirror in the handpiece needs to be clean and dry.
  • Tips – zirconia (cheaper), sapphire, different diameters and lengths.
  • Settings- Energy, water, pulse repetition rate, power.
  • 1-2 mm away hard tissues, near or touching for soft tissues.
  • 2.5 W, 25 Hz, h mode, 40% air, 20% water for soft tissues.
  • Always keep in h mode.
  • Test fire – before use fill the line with water– no popping stop and check! The water is essential for cooling the tissues.


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