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1 Laser in orthodontics Laser in orthodontics Prepared by: Prepared by: Dr. Mohammed Alruby Dr. Mohammed Alruby Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
2 Introduction Characteristic of light History Laser physics and properties Component of laser Classification of laser Biological effect of laser Laser effect on dental tissues Laser safety in dental practice General application of laser Personal protective equipment Types of laser intensity in orthodontics Uses of laser in orthodontics Effect of laser in orthodontics Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
3 Introduction: Laser means: (light amplification by stimulated emission of radiation) Light has been used as a therapeutic agent for many centuries Light is a form of electromagnetic energy that exists as a particle, and travel in waves at constant velocity The basic unit of this radiant energy is called photon Characteristic of light 1-Amplitude: the total height of the wave oscillation from the top of the peak to the bottom of the vertical axis (the larger the amplitude the greater the amount of energy generated) 2-Wave length: is the distance between any two corresponding points on the wave on the horizontal axis 3-Frequency: is the oscillation / second and is inversely proportional to the wave length: Shorter wave length ------- higher the frequency and vice versa N: B: Joule: is the unit of energy The development of laser in dentistry has allowed the dental professional to provide comfort and better treatment for the patient Laser is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons History of Laser 1704: Newton characterized light as a stream of particles 1803: discover the polarity of light and, light was emitted in the form of waves 1880: Maxwell described the concept of electromagnetic radiation Maxwell electromagnetic theory: explained light as rapid vibration of electromagnetic fields due to oscillation of charged particles 1917: Albert Einstein, explained about laser light He describes the stimulated emission of light by three process 1-Absorption: Each atom consists of centrally placed nucleus which contain positively charged particles: electron. When atom is struck by a photon, there is an energy transfer causing increase in energy of the atom 2-Spontaneous emission: The electron within the atom pumps to a higher energy level The atom is pumped up the ground state to excited state In the excited state the atom is unstable and will soon spontaneously decay back to ground state, releasing the stored energy in the form of emitted photon 3-Stimulated emission: If an atom in the excited state is stuck by 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 wave length to leave the atom. N:B: In small spaces at the speed of light, this photon chain reaction produces a brief intense flash of mono-chromatic and coherent light which termed as laser. Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
4 1953: Charles Townes, experimenting with microwaves produce a device whereby this radiation could be amplified by passing it through ammonia gas. This was the first MASER (microwave amplification by the stimulated emission of radiation), and was developed as an aid to communication system and time keeping 1960: inventing the 1st laser at the Hughes air craft company –USA- using medium of Ruby that was stimulated using high energy flashes of intense light 1964: Ralph Stern and Rieder Sognnas used the Ruby laser to vaporize enamel and dentine 1969: Leon Goldman used the laser clinically on enamel and dentine Laser physics Laser is a device that converts electrical or chemical energy into light energy In contrast to ordinary light that is emitted spontaneously by excited atoms or molecules retain excess until it is stimulated to emit it The radiation emitted by laser including both visible and invisible light is more generally termed as electromagnetic radiation Properties of light: There are several important properties of laser light that distinguish it from the normal light: 1-Mono-chromatism: Laser emit light that is mono-chromatic, has single color ranging from infra-red to invisible spectrum 2-Collimation: Laser beam travel within spatial boundaries parallel to each other Beam has constant shape and size Most of gas and solid state laser emit laser beam with divergence angle of approximately a miliradia, this explains why laser light is extra-ordinary hazardous This property is important for good transmission through delivery system 3-Coherency: The light waves are all in the same phase and have identical eave length There are two types of coherence: a-Longitudinal: represent time coherence along longitudinal beam b-Transverse: coherence cross the beam 4-Brightness: Arise from parallelism or collimation of the laser light as it moves through space maintaining its concentration High brightness factor translate to high concentration of energy when the laser is focused on a small spot The focusing of the brightness of the laser beam is what the clinician depends on to elevate the temperature of the tissue or to cut or to vaporize the tissues 5-Excellent concentration of energy 6-Zero entropy Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
5 n Ordinary light 1 Multiple polychromatic 2 Non directional 3 Non focused Laser light Typically one color monochromatic specific wave length Directional collimated beam Highly focused wave length—white light 4 Unorganized- incoherent Organized efficient – coherent energy 5 Low intensity 6 High intensity Components of laser -Active medium -Pumping mechanism -Optical resonator -Delivery system -Cooling system -Control panel 1-Active medium: laser medium Determine the wave length emitted from the laser Material may be: Gas: co2, Argon, Krypton Solid: ND:yag (neodymium doped yttrium aluminum garnet), Er:Yag, Ruby Liquid: an organic die as: Rhodium Semiconductor crystals: Diode 2-Pumping mechanism: Represent a man-made source of primary energy that excited the active medium ((flash light or arc light)) Energy from this primary source is absorbed by the active medium, resulting in the production of laser light This process is very inefficient, with only some 3-10% of incident energy resulting in laser light, the rest converted to heat energy 3-Optical resonator: Laser light produced by the stimulated active medium that bounced back and forth through axis of the laser cavity, using two mirrors placed at either ends, thus amplifying the power Distal mirror is totally reflective Proximal mirror is partly trans missive So that, at a given energy density, laser light will escape to be transmitted to the target tissue 4-Delivery system: The beam of laser should be delivered to the target tissue in a manner that is ergonomic and precise Types: a-Fibro-optic: quartz silica fiber with a hand piece diode, ND:Yag, Er:Yag b-Hollow tube wave guide: hollow tube lined with a series of well –aligned mirrors which reflect the laser beam from the unit to the hand piece – co2, Er:Yag Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
6 == the development of these delivery system in accessible areas of oral cavity makes more and more applications possible ** dental laser can be used either in contact or non-contact mode 1-Contact mode: the fiber tip is placed with the tissue and there is a control feed-back for the operator 2-Non-contact mode: fiber tip is placed a way from the target tissue The clinician operator with visual control with the aid of an aiming beam or by observing the tissue affect being created ** according to excitation source: there are two basic wave length emission: (beam mode) 1-Continuous mode: the laser energy is emitted continuously as long as the laser activated and produces constant tissue interaction Co2 and Diode laser operate in this manner Pulse duration can range from tenths of seconds to several hundred microseconds 2-Pulsating mode: emits energy in severe of pulses with a resting time in between, this allow the tissue to cool un between each energy delivery and minimize heat conduction with optimum benefits p = Nd:Yag, Er: Yag, devices operate as free –running pulsed laser 5-Cooling system: = co-axial coolant system may be air- or water assisted = represent the bulkiest component = Erbium laser employ a water spray for cooling hard tissue 6-Control panel: Allow variation in power output with time Other facilities may allow wave length change ((multi-laser instrument)) Classification of laser 1-Based on active medium: Solid state: Nd: Yag, - Ruby, Diode, - KTP, - Ho-Yag Liquid state: Rhodium Gas state: co2, -- argon, -- krypton, --- helium-neon 2-Depending on wave length: Hard laser: comes in infra-red spectrum (less than 700nm) As:co2, - Nd: Yag—argon laser Soft laser: comes in wave length (140-400 nm) & visible light (400—700 nm) as diode laser 3-Based on safety procedure: Class 1: safe under all condition: fully enclosed system as: Nd: Yag – laser used in dental laboratory Class 2: output is 1mw – visible low power laser visible red aiming beam of surgical laser Class 3A: visible laser above 1milli watt, - no dental examples Class 3B: upper continuous output limit is 0.5w --- low power diode laser used for bio-stimulation Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
7 Direct viewing is hazardous to the eye Class 4: output excess of class 3B, are used for cutting and drilling All lasers used for oral surgery Whitening and cavity preparation Direct or indirect viewing is hazardous to eye Types of laser 1-Argon Ion Laser: Ionized gases state: has two wave lengths: 488 nm blue color, 514 nm blue green Deliver energy by: gated or continuous mode Absorbed in pigmented tissue and hemoglobin Useful as: good hemostatic activity, vascular lesion, acute inflammatory of soft tissue lesion 2-Helium – Neon laser (HE-Ne): First continuous wave laser: gas state Typical representation of class neutral – gas atomic laser Useful as tool for: -Application of biology and medicine -Adjusting optical and mechanical system -Holography and intero-fermetry 3-Co2: carbon dioxide laser: Non-contact mode laser, the beam does not contact the tissue during the cutting phase, guided by hand piece Gas state laser: well absorbed by water, fast thermal reaction Wave length: Rapid soft tissue remover Shallow depth of penetration Useful cutting dense fibrous tissue Highest rate of absorption by hydroxyapatite 4-Diode laser: Solid state active semiconductor Wave length: 812 to 989 nm Continuous and gated pulse (MODE) Energy is absorbed by pigmentation in the soft tissue Used in contact mode and also provides tactile feed-back during the surgical procedure Can be used without anesthesia to perform very precise anterior soft tissue esthetic surgery Used in: bleaching, endodontics, soft tissue surgeries and periodontics 5-Erbium laser: Solid state used in hard tissues, its wavelength is: 2790 – 2940 nm, which is ideal to absorbed by water and hydroxyapatite Built with two different crystals: 1-Er: Yag: (Erbium yttrium aluminum garnet crystals) 2-Er, Gr: YSGG: (Erbium Chromium sensitized Yttrium Scandium Gallium garnet crystals) Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
8 Bone cutting with Erbium lasers result in minimal thermal and mechanical trauma to adjacent tissues A traumatic effects and excellent healing response Very short laser pulse 50 – 100 microseconds are typically used for hard tissue procedures 6-Nd: Yag laser: Neodymium Yttrium Aluminum Garnet, solid state active Developed in 1964 Wave length 1064 nm and can easily absorbed by pigmented tissues Deliver energy in free running pulse mode Useful for: -Root canal sterilization -Cutting and coagulation -Periodontal surgery Fibro-optic delivery system Biological effects of laser Once laser beam is produced it is aimed at tissue to perform a specific task As the energy reaches the biological interface, one of four inter-actions will occurs: absorption, - reflection, - transmission, - scattering, 1-Absorption: Chromophores: specific molecules in the tissue that absorb laser light energy. The light energy is then converted into other form of energy to perform work Main chromophore seen in oral tissues are hemoglobin, melanin, pigmented protein, hydroxyapatite and water Each wave length has specific chromophores that absorb energy == diode and Nd: Yag mostly absorbed by pigments such as hemoglobin and melanin == Erbium and co2 laser are predominantly absorbed by water == Erbium wave length also exhibiting some hydroxyl apatite absorption == the shorter infra-red wave length of diode and Nd:yag lasers penetrate tissue more deeply than the longer mid infra-red wave lengths of the Erbium and co2 lasers Thermal relaxation: Ability to control a progressively increasing heat loading of target tissue Thermal relaxation rates are direct proportion to the area of tissue exposed and inversely proportional to the absorption coefficient of the tissue Factor that influence absorption and thermal relaxation: 1-Exposure time and laser emission mode: thermal relaxation will occur least with continuous wave emission and maximally in free running pulsed delivery 2-Laser incident power (joules/ second) 3-Laser power density (watt per square centimeter): for any chosen level of incident power, the smaller the beam diameter, the greater concentration of heat effects 4-Beam movement: rapid laser beam movement will reduce heat built –up and aid thermal relaxation 5-Endogenous coolant: blood flow Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
9 6-Exogenous coolant: water, air, per-cooling of tissues 7-Incident angle of laser beam: = maximum control of laser tissue inter-action can be achieved if the incident laser beam is perpendicular to the tissue surface = reducing the incident angle towards the inter-active angle of the tissue surface will increase the potential for true light reflection with an associated reduction in tissue changes 2-Reflection: When angle of incidence less than the infra-active angle, result in total reflection of the beam In true reflection, the incidence and emergence angles will be the same If the medium inter-face is rough or non-homologous, some scatter may occur 3-Transmission: Entrance of beam in the medium but there is no inter-action between the incidence and the tissue The beam will emerge --- distally unchanged or partially refracted 4-Scattering: Once the laser energy enters the target tissue, it will scatter in various direction This phenomenon is usually not helpful but can help with certain wave lengths bio-stimulative properties ** there are five important types of biological effects that can occur once the laser photons enter the tissue: 1-Fluorescence: The amount of fluorescence is related to the size of lesion and this information is useful in diagnosing and managing early carious lesion 2-Photo-thermal: Occurs when the chromophores absorb the laser energy and heat is generated This heat is used to perform work such as incising tissue or coagulating blood Heat is generated during these procedures and great care must be taken to avoid thermal damage to the tissue 3-Photo disruptive: = Hard tissues are removed through a process known as photo-disruptive oblation = Short pulsed burst of laser light with extremely high power interact with water in the tissue and from hand piece causing rapid thermal expansion of the water molecules = This cause thermos-mechanical acoustic shock wave that is capable of disrupting enamel and bony matrix quite efficiency = Thus tooth and bone are not vaporized but pulverized instead through the photo-mechanical ablation process. This shock wave creates the distinct propping sound heard during Erbium laser use. 4-Photo-chemical: Reaction occur when photon energy causes chemical reaction, these reactions are implicated in some of the beneficial effect found in bio-stimulation. 5-Photo bio-modulation or bio-stimulations: Laser ability to: speed healing increase circulation reduce edema minimize pain == some studies exhibit effects: Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
10 Increase collagen synthesis Increase fibroblast proliferation Increase osteogensis Enhanced Leukocyte phagocytosis == the exact mechanism of these effect is not clear, but it is may occurs mostly through photo- chemical and photo-biological interactions within the cellular matrix and mitochondria == bio-stimulation is used dentally to reduce post-operative discomfort and to treat recurrent Herbs and Aphthus stomatitis N: B: When laser heats oral tissues, certain irreversible or reversible changes can occur: 1-Hyperthermia, below--------- 50 degree 2-Coagulation and protein denaturation: -------- more than 60 degree 3-Vaporization: ---------- more than 100 degree 4-Carbonization: --------- more than 200 degree Irreversible effects such as denaturation and carbonization results in thermal damage that causes inflammation, pain, edema. Laser effect on dental tissues 1-Thermal effects: Laser energy is converted into thermal energy or heat which destroyed the tissues, the laser beam couples to the tissue surface and this absorption leads to heating of the surface as follow: -45 --- 60 degree ----------------- denaturation -More than 60 degree ------------ coagulation and necrosis -More than 100 degree ------------ vaporize the water inside the tissue -More than 300 degree ------------ carbonization and pyrolysis The laser light will be absorbed and converted to thermal energy by stimulating the lattice vibration of the tissue molecules, this leads to heating the surrounding tissue to a boiling of water followed by carbonization and tissue removal Damaged to adjacent tissue is manifested by massive zones of carbonization, necrosis, and cracks. 2-Mechanical effect: -Photo-ablation: fast thermal explosion, mechanical shock waves -Photo-disruption: non-linear tissue behavior. Optical breakdown Mechanical shock waves 3-Chemical effects: Alteration in the chemical and physical properties of the tissues and this depend on: -Wave length, energy density, pulse duration -Optical properties of hard tissue 4-Thermo-mechanical effects: Due to good absorption of laser in water as well as in hydroxyapatite, the laser radiation leads to fast heating of water inside, that lead to an explosive expansion In enamel: cracks always found Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
11 In dentine: no cracks are seen but more thermal damaged like carbonization and necrosis are found. Effect on pulp: -If pulp temperature below 5 degree---- odontoblastic layer may not be present -Use of water and air combination before, during or immediately after laser irradiation may be effective of temperature control and reduction of heat transfer to pulp -Continuous mode: ------ pulpal necrosis -Pulsed mode: ------------ may result in new dentine formative -At 6 degree ---- result in irreversible pulpitis -At 11 degree results in necrosis of pulp == air water cooling is used with laser system such as, co2 holmium and Erbium, this can provide adequate heat protection to the pulp equivalent to that of the common dental drill Effect on hard tissues: 1-Micro-cracks and zone of necrosis 2-Carbonization 3-Cracks on enamel and dentine 4-Increase micro-hardness of dentine 5-Organic matrix burn off 6-Crystalline structure of hydroxyapatite changes 7-Transformation of apatite to tri-calcium phosphate 8-Inhibition of enamel subsurface demineralization (prevention of caries) Laser safety in dental practice 1-Tissue hazards: Retinal and corneal injury More than 20 degree above body temperature ------ cell destruction and denaturation of cellular enzymes and protein Histological, thermal coagulation necrosis is produced Ablation of oral tissue by carbon dioxide laser, char layer or carbonized layer is formed -This char layer is strong absorbent layer for different wave lengths -Mechanical removal of char layer is essential 2-Environmental hazards: = potential inhalation of air born hazardous material that may be released as a result of laser therapy = some lasers contain inert gases (argon, krypton, xenon) mixed with toxic gases such as fluorine or hydrogen chloride as the active medium = inhalation of toxic material in the form of aerosol has been found potentially damaging to the respiratory system = standard surgical masks and surgical smoke evaluation equipment is used in the theater = greatest procedure of smoke –co2 and Nd: Yag laser 3-Combination hazards: Flammable solids, liquids and gases used within the surgical setting can easily ignited if exposed to the laser beam The use of flame resistant material and other precautions therefore is recommended Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
12 4-Electrical hazards: Electrical hazards of laser can be grouped as: -Electrical shock hazards -Electric fire hazards or explosion Shielding grounding and housing high voltage electrical component ----------- provide protection under circumstances from electrical injury General application of laser 1-Selective removal of caries: Nd:Yag, Co2, Er:Yag 2-Cavity preparation: Nd:Yag, Er:Yag 3-Pit and fissure sealant: Er:Yag 4-Composite curing:Argon laser 488nm. 5 sec Increase bond strength and surface adhesion 5-Bleaching: argon, Nd:Yag, Co2 Laser light is converted to haet as it strikes the bleaching gel accelerate the oxidation Immediate result and more convenient improved appearance 6-Pulpal therapy: Research with Nd:Yag and Co2 laser has verified the value of avoiding formcresol using Pulp capping and pulpotomy: Co2 laser is used as it: -Arrest bleeding -Disinfect dentinal exposure -High success rate 7-Root canal wall preparation: straight and slightly curved canals 8-Root canal filling by gutta-percha and laser: Gutta-percha is thought to be melted by laser heat energy, this is possible by vertical condensation method but time required is too much 9-Desensitization of hyper-sensitivity of dentine and teeth: Diode, Nd:Yag, Co2 After drying the hypersensitive dentine, the laser tip is placed in a direct contact with the tooth surface which is then irradiated for a period of 30 sec --- 3min, after 4 months, there is reduction in hypersensitivity Limitation of use: -Special training and attention for safety -No single laser can perform all desired dental application -Expensive Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
13 Personal protective equipment 1-Eye protection: Light produced by laser presents potential hazards for ocular damage by either viewing or reflection of the beam Adequate eye protection must be worn by the operator as well as the patient They are available in the form of safety goggles or screening devices Laser protective eye wear filters are specified according to their optical density which takes account the wave length, power and diameter of the beam 2-Laser filtration masks: Prevent air born contamination 3-Foot pedal control switch with protective hood: Prevents accidental depression by surgical staff Types of laser intensity in orthodontics A-High intensity laser therapy: 1-Light curing for: -Light cured material -Conventional and fast quartz- halogen light -Light emitting diode (LED) -Plasma arc unit -Argon laser 1-Enamel conditioning for bracket bonding 2-Bonding to porcelain 3-Increase enamel resistance to prevent white spot lesions 4-Bracket debonding 5-Welding – soldering, - brazing 6-Laser minor surgery: -Fibrectomy -Gingivectomy -Frenectomy B-Low intensity laser therapy: Low level laser therapy (LLLT) is known as soft laser therapy Use He-Ne gas laser was used and some clinical procedure use semi-conductor Diode laser Thermal effect of LLLT on dental tissue is not significant The wave length used in LLLT has poor absorption in water and thus penetrate soft and hard tissues from 3mm up to 15mm History: Light therapy is one of the oldest therapeutic methods used by human The use of lasers and LED as light source was the nest step in the technological development of light therapy Mechanism of action: Depend on absorption of particular visible red and near infra-red wave length in photo-receptor within subcellular component, particularly the electron transport chain within membrane of mitochondria Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
14 == Absorption of light --------- short activation of respiratory chain -------- stimulate oxidative phosphorylation ----------- changes on mitochondria and cytoplasm == Electron transport chain ----- increase supply by ATP as well as increase the electrical potential of mitochondria membrane that lead to ---------- increase primitive force to the cell ----- -------- alkalization of the cytoplasm and activation of nucleic acid synthesis == LLLT stimulate the normal function of the cell Primary response: -Photon are absorbed by cytochromes -Singlet oxygen free radicals are generated, affect ATP synthesis and thus increase energy available to the cells -Nitric oxide is produced -Reversible increase in the cell membrane permeability to Ca Secondary response: -DNA and RNA synthesis -Cell proliferation -Growth factor release -Collagen synthesis by fibroblast -Changes in nerve conduction Contraindications: 1-Area of malignancy or suspected malignancies 2-Patient with coagulation disorders and photo-sensitivity 3-Caveats in pregnancy in case of large dose 4-Patient with pace-makers 5-Testicles and diabetic wounds Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
15 Uses of Laser in Orthodontics 1-Laser itching in orthodontics: = Split the bond of organic and inorganic substances on the surface explosive vaporization of water modifies the smooth surface of enamel = No harmful increase in the temperature of the pulp due to efficient heat conductance through the hard substances. Painless method does not involve either vibration or heat = Laser itching of enamel creates micro-cracks that are ideal for resin penetration, the surface produced by laser is also acid resistant = Lesser modifies the calcium phosphate ratio and leads to the formation of more stable and more less acid soluble compounds, thus reducing the susceptibility to caries attack = saving chair time and improve adhesion because it reduces the risk of salivary contamination = Different types of laser are used as: Co2, Er:Yag, and Nd:Yag Fuhman et al 2001: concluded that co2 and Nd:Yag laser produce enamel conditioning and tensile bond strength sufficient to meet the requirements of bracket bonding Ariyaratnam et al 1997: belived that Nd:Yag laser when compared to 37% phosphoric acid, produce lower bond strength and alter the surface morphology of enamel The dentinal surface that exposed to Nd:Yag laser exhibit micro-cracks and fissures and this not suitable method for dentinal acid itching Fabri et al 2011: re-itching with acid phosphoric will be necessary if Er, Gr:YSGG laser is used for tooth preparation or surface treatment 2-Bonding: Argon laser is commonly used as light curing adhesives, the procedure the same as the conventional one -Laser tip was held 0.5mm from the bracket and the light curing was kept touching the bracket -No enamel damaged caused by Argon lasers at energy levels of 1.6 to 6 watts Bonding to porcelain: Conventional acid itching is unable to produce sufficient bond strength of orthodontic bracket to porcelain surface The application of 9.6% hydrofluoric acid for 2min provide suitable alteration for orthodontic bonding, but it can damage the surrounding teeth and soft tissues so need careful isolation = Li et al 2000 prepared porcelain with Nd:Yag laser for bonding and found that this type of laser with combination of composite light cure created acceptable bond strength to porcelain = Poosti et al 2011 evaluate shear strength following Nd:Yag and Er:Yag and found that, nd:Yag has good results and more power than Er:Yag laser. 3-Increase enamel resistance to prevent formation of white spot lesion: == Initial signs of demineralization on the enamel surface due to dissolution of calcium and phosphorus ions from the enamel surface due to oral bacteria Most commonly present in upper anterior teeth and upper, lower premolars (Lovrov et al) == In 1965 Sognnaes and Stern, the 1st reported that when the enamel was exposed to Ruby laser irradiation, the resistance of enamel to acid attack was improved Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
16 Theory: surface melting through partial fusion and re-crystallization of enamel prisms, and changes in enamel’s organic matrix == Moslemi et al 2009: combining the laser irradiation with fluoride treatment could have a synergistic effect on acid resistance == Dincan and Otsuka 1992: found, Co2 laser treatment reduce the threshold of PH at which dissolution occurred == Lenz et al suggested that the enamel surface is sealed by laser and is less permeable for the subsequent diffusion of ions into and from the enamel Argon laser irradiation of enamel reduces the amount of demineralization by 30 -50% N: B -In sound enamel, Ca, phosphorus and fluoride ions diffuse into the acid solution and are released into the oral environment -With lased enamel, the micro-spaces created by laser irradiation, trap the released ions and act as sites for minimal re-precipitation with enamel structure -So the lased enamel has an increased affinity for calcium, phosphorus and fluoride ions, this will prevent demineralization 4-Laser debonding of ceramic orthodontic bracket: Laser light has been shown to degrade resin by thermal softening and no bracket or enamel damaged Ideal debonding time 0.5 sec show no pulp reaction No enamel tear outs Laser used Nd:Yag and Co2 laser 5-Bracket mesh designing: new bracket with laser reinforced structure bases, the base of the brackets guarantees an excellent bond during the entire treatment period compared with conventional type, the laser one cannot abraded and does not contain coloring agents 6-Accelerated tooth movements: Methods of increasing tooth movements are injection of: prostaglandin, active form of VitD, osteocalcin OR: electric stimulation, Corticotomy, resonance vibration OR: low level laser therapy LLLT, Yamachi et al 2010: LLLT accelerate the process of bone remodeling Other studies reported that 56% increase in rate of tooth movement in first 3 months and later 30% 7-Reducing orthodontic post adjustment pain: LLLT has been shown to produce analgesic effect LLLT has benign stimulating influence on depressed neurons and lymphocytes Laser unit used in Ca diode laser 8-Laser welding: Welding: joining of two metal pieces by applying heat, pressure or both without use of intermediate alloy. Used for joining flat structure as band or bracket Types: Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
17 a-Pressure welding: Achieved by applying sufficiently large force to the metal parts to be joined b-Spot (resistance) welding: Used to joined flat structure such as band and brackets and also to join different types of orthodontic wires In spot welding the parts to be joined should be pressed firmly together between electrodes usually made of cupper, then high electric current is passed through the system c-Laser welding: Used for welding of dental alloys Laser light is focused on small region, applying high energy to these areas in short amount of time Heating is mainly focused on point of application Produces deep penetration welds with minimum heat effective zone Welding dissimilar metals while producing very low heat Weld is approximately 1mm wide and the surrounding materials is not distorted Because the weld bead is small, there is usually no need for finishing or re-working and this reduces coasts N: B: Orthophaser: Unit bigger than the conventional spot welder Provide highly superior results Unit consists of working microscope with eye protection Gas used is Argon Advantages of laser welding: 1-Processes high alloy metals without difficulty 2-Can used in open air 3-It can be transmitted over long distances with minimal loss of power 4-Low thermal output 5-Welds dissimilar metals 6-No filter metals necessary 7-No secondary finishing necessary 8-Extremely accurate Disadvantages of laser welding: 1-Rapid cooling rate may cause cracking in certain metals 2-High coast 3-Application surfaces easily damaged 4-High maintenance cost N: B: Soldering: Process of joining two metals by using fillers, used to make electrically strong joint between metals which can withstand all electrical load Brazing: Similar to soldering but: Used to make mechanical strong joint which can withstand with all mechanical load and stresses Both possess a lower melting point than that of metals that joined Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
18 Intra-oral laser micro-welding: High power Neodymium laser, deliver 20 jouls/pulse Rapid and repeatable action of Neodymium laser intra-orally is safe and creates no damaged to dental tissues Used in: -Placement in space maintainer -Retainers -Orthodontic splint -Periodontal splint -Attachment of bands and auxillaries It eliminates time consuming procedure It eliminates need of painful intra-oral soldering It eliminates the process of crimping and clamping 9-Laser minor surgery: Advantages: 1-Tissue excision more precise than scalpel 2-Coagulate blood vessels, seal lymphatics, sterilize the wound 3-Maintaining clean and clear surgical field 4-Shorter operative time and faster post-operative recuperation 5-Used only with topical anesthesia 6-Less bleeding – minimal swelling – no need of suture 7-Less discomfort and complication post-operative Disadvantages: high expensive Surgical lasers have: -Central zone of carbonization surrounded by zone of vaporization, coagulation and protein -Stimulating zone During laser curettage, sufficient hemostasis and significant reduction of initial levels of periodontal pathogens are achieved Soft tissue laser can significantly reduce treatment time by creating access for bracket, / bands, improving racket placement by improving tooth proportionality, and helping mange oral hygiene through removal of: a-Pseudo pockets b-Shaping and contouring of gingival tissue during treatment c-Fibrotomy to provide long term stability of teeth with severe rotation before treatment {diode laser with 808nm wave length and 0.4 fiber diameter was used} d-Frenectomy, usually indicated to prevent relapse after correction of midline diastema Hytac 2006 reported Co2 laser for frenectomy and provide better function Kora 2009, Nd:Yag laser treatment for soft tissue disorder provides better patient perception of success than those seen with conventional surgery e-Removal of opercula on second molar by laser that facilitate exposure of teeth to allow band placement f-Tissue removal to allow bracket placement on partially erupted tooth g-Management of aphthus ulcer by laser: promote healing and eliminate painful results Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
19 h-Management of impacted teeth: in case of slow eruption – delayed eruption – impaction Diode laser is used to allow removal of tissue barrier and allow bonding of attachment 10-Depigmentation of gingiva by laser: Remove gingival pigmentation and helps in restoring the lost ethics 11-Diagnostic laser: A-Holography: 3D laser scanning and re-construction Use to assess cross sectional growth changes and clinical outcomes in orthognathic surgery This system allows photo-realistic generation of the face that could be viewed from any direction This polygonal facial model could be used to measure facial land mark and volumes The application of laser holography in orthodontic are: 1-Facial soft tissue analysis: Detect the changes in facial soft tissue produced by growth or treatment The scanning process is no invasive and normally completed within few seconds The data is accurate to approximately 0.5mm Other advantages: the coast, speed, probability 2-Digital models: Orthodontic study models are usually collected by clinicians to aid: Diagnosis Monitor treatment Complement the written record Research audit and teaching = hologram for orthodontic models have the potential for: Assessing tooth size Assessing arch form Assessing tooth arch discrepancies = some investigators have performed 3D superimposition of dental casts to analyze orthodontic tooth movements = most parameters on digital models can be reliably measured =digital models can potentially eliminate the requirement for the production and storage of dental casts N: B: Hologram: produced by Dannis Gaber 1947, take Nobel prize at 1971 B-Laser Doppler flometry: LDF Developed in 1970 as non-invasive electro-optical technique to measure the velocity of red cells in skin capillaries The original technique utilized a light beam from (He-Ne) laser emitting at 632nm Uses: 1-Diagnosis of pulp vitality in human teeth 2-Monitoring pulpal flow 3-Investigate the pulp response to orthodontic forces or orthopedic forces C-Laser florescence for caries detection: LF Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
20 The early detection of initial caries formed around orthodontic bracket is possible aiming to minimize the damage of caries lesion in orthodontic patients LF device method based on emission of light from diode laser at 655nm wave length and measure the fluorescence emitted mainly from caries tissues At this wave length, clean healthy teeth exhibit little or no fluorescence in contrast, the demineralized teeth exhibit fluorescence proportionate to the degree of demineralization The fluorescence is believed to originate from proto-porphyrin IX and related metabolic products of oral bacteria LF device may be useful for assessing the severity, progression and depth of white spot lesion during orthodontic treatment Two versions of LF device are available: 1-Older version: introduced 1998 used to detect occlusal and smooth surface caries 2-New version: used to detect proximal surfaces D-Laser spectroscopy: Used in the field of dentistry for the purpose of analyzing the surface structures of dental material Used for evaluating the surface roughness of orthodontic wires and brackets and the surface changes in orthodontic materials 12-Laser orthopedics: Lasers can have applied to manipulate the facial growth Irradiation of TMJ by LLLT during mandibular advancement increase bone formation in condylar region (630nm for 3 weeks) while no increase in cartilage thickness and fibrous tissues Effects of laser in orthodontics 1-Pain reduction: Pain or discomfort is a common experience during fixed orthodontic treatment Pain usually appear several hours after force application and slowly increase until 24 hours, then return to the basic level at approximately 5th days. This pain cycle is repeated after each appointments The pain is produced due to changes in blood circulation of PDL causing ischemic area, so heavy force produces more pain, also pain produced by formation of metabolic products such as prostaglandin that stimulate pain receptors Pain is reduced by use anti-inflammatory drugs (NSAID) or by using LLLT ( He-Ne laser) also used but need more time during exposure (32-37 min) Mechanism of pain relief: a-Direct action on nerve: inhibit the activity of sodium potassium ATP b-Laser energy can re-activated the inactive enzymes c-Produce ATP in dysfunctional muscles d-Laser help in production of ATP that lead to pain reduction e-Reduction of prostaglandin level (allogenic substances) Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
21 2-Tooth movements: By using LLLT stimulate acceleration on tooth movement through increase chemical mediators and cellular differentiation and cell activity N: B: Pressure tension theory: The force application in some area causing compression on PDL due to tooth displacement within PDL, while other parts has tension which blood flow maintained or increased. The alteration in blood flow create changes in the proportion of oxygen and other metabolites within PDL which can stimulate the release of active elements These chemical alterations stimulate cellular differentiation and cell activity 3-Distraction osteogensis: Method to induce bone formation and investing soft tissue under the influence of tensional stress at osteomatized sites of healing bone Distraction: new bone formation + new soft tissue formation. Uses: 1-Lengthening of ramus in patients with hemi-facial microsomia 2-Severe maxillary deficiency 3-Widen mandibular symphysis Steps of distraction: 1-Osteotomy 2-Latency period between bone fracture and initiation of tensional stress to the bone. Reparative callus is allowed to form 3-Distraction phase: gradual traction is applied to the bone to create new bone at the surgical sites 4-Consolidation phase: period between the end of traction application and the removal of distraction device This stage is necessary to allow complete mineralization of new bone formed and this phase take a long time, so lead to some discomfort By using LLLT accelerate the process of bone regeneration during consolidation 4-Retention and Relapse: LLLT effect on relapse tendency of orthodontically rotated teeth have not fully characterized Other study by Kin et al 2010, and concluded that LLLT of orthodontically rotated teeth without retainer increase the rotational relapse of teeth compared with control group 5-Growth modification: == maxillary expansion: LLLT effect on maxillary expansion depend on the total dosage, frequency and duration of treatment and slowed 20% to 40% better results == mandibular growth: When the mandible is deficient as seen in most class II patients, the growth modification is suitable treatment option By using LLLT increase the bone and cartilage formation, so that the treatment might be easier and more stable Several studies on rats showed that significant increase in mandibular length and help in correction of class II malocclusion Laser in orthodontics Laser in orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby
