LASERS IN ENDODONTICS

It includes 3 importants concepts of PAD,LAI and PIPS

1. LASERS IN ENDODONTICS PRESENTER: DR.RITIKA MUNDHRA (MDS III YEAR)

2. HISTORY OF LASERS “Laser” is an acronym of light amplification by stimulated emission of radiation. 1.1958 Charles Townes and Arthur Schawlow coined the word “maser” 2. Word laser was first coined in 1957 by Gordon Gould 3. Theodore Maiman , who introduced the acronym “laser,” 4. 1965, the physicist Leon Goldman was the first to use a ruby laser

3. What is a wavelength ? What is electromagnetic spectrum? What is Visible spectrum of radiation ? What is invisible spectrum of radiation?

4. CLASSIFICATION OF DENTAL LASERS 1.BASED UPON THEIR WAVELENGTH ULTRAVOILET 130-400 nm 2. VISIBLE 400-700 nm 3. NEAR INFRARED 700-1500 nm 4. MEDIUM INFRARED 1500-3000 nm 5. FAR INFRARED >3000 nm

5. CLASSIFICATION OF DENTAL LASERS ULTRAVOILET VISIBLE NEAR INFRARED MEDIUM INFRARED FAR INFRARED EXCIMER BLUE ARGON LASER DIODE 810 nm Er.Cr.YSGG CO2 LASER 9300 nm 308 nm 470-488 nm DIODE 940 nm 2780 nm CO2 LASER 9600 nm GREEN ARGON LASER DIODE 970 nm CO2 LASER 10,600 nm 514 nm DIODE 1064 nm Er: YAG GREEN KTP LASER Nd:YAG 1064 nm 2940 nm 532 nm Nd:YAP 1340nm

6. 2. BASED ON THEIR PENETRATING POWER: 1. SOFT TISSUE LASER DIODE LASER 445-1064 nm (ATHERMIC LASER) Nd: YAG LASER 1064 nm Nd: YAP LASER 1340 nm CO2 LASER 10,600 nm 2. HARD TISSUE LASER Er.Cr.YSGG LASER 2780 nm (THERMIC LASER ) Er.YAG LASER 2940 nm (SURGICAL LASER) Excimer 308 nm

7. 2. BASED ON THE TYPE OF ACTIVE MEDIUM USED: 1. GAS LASER He:Ne LASER CO2 LASER 2. LIQUID LASER DYLASE 3. SOLID LASER RUBY LASER Nd:YAG LASER Er.YAG LASER Ho:YAG LASER 4. SEMICONDUCTOR LASER DIODE LASERS [GALLIUM ARSENIDE LASER]

8. According to ANSI and OHSA standards : CLASS POWER NATURE Class I LOW SAFE Class IIa LOW HAZARDOUS>100s Class IIb LOW Hazardous >0.25 s Class IIIa MEDIUM Hazardous <0.25 s Class IIIb MEDIUM Hazardous {viewed directly} Class IV HIGH Ocular Skin and fire Hazards >0.5 W

9. CLASSIFICATION OF LASERS USED IN ENDODONTICS

10. DIFFERENT LASERS USED IN ENDODONTICS ARGON LASER: It produces different kinds of wavelengths, among them two in the blue spectrum (470–488 nm) and one in the green spectrum (514 nm). The possibility of using the B lue argon laser (470 nm) (Showa University School of Dentistry, Tokyo, Department of Endodontics, in 1998 and 1999) A bility of argon laser for smear layer and debris removal from the root canals, prepared in a conventional way and irradiated at 1 W, with 0.05 s pulse duration and 5 Hz pulse frequency

11. 2.KTP LASER Potassium Titanium Phosphate Laser : 1.In the spectrum of visible light, in the green band, the wavelength 532 nm was chosen for the construction of the KTP laser (a duplicate neodymium of 532 nm) , with high affinity with hemoglobin 2.It has the capacity for soft tissue cutting and coagulation 3.It’s root canal decontamination ability after conventional endodontic instrumentation was studied, at different power output (at 1 and 1.5 W), in dry mode or wet model

12. 3.DIODE LASER Introduced in 1980’s initially for treatment of dentin hypersensitivity and to bio-modulate the inflammatory response during vital pulp therapy (pulp capping or pulpectomy) Today, diode lasers represent a valid alternative to Nd:YAG lasers root canal decontamination. The active medium is a semiconductor, which is, nowadays, miniaturized, made up of various layers (wafer-like construction). The gallium arsenide (GaA1As), doped with aluminum atom or indium as doping atom ( IGaAsP ) .

13. 3.DIODE LASER It uses an optic fiber (diameter 200–300–400 μm ) which ends in a terminal handpiece, going through it and coming out in a terminal curve tip.

14. 3.DIODE LASER The fiber/tip activation is performed at 1 W on dark-blue articulating paper, repeating the procedure 4–5 times up to seeing the tip becomes darker The use of thin fiber (200 μm ) inside a root canal permits decontamination in the endodontic system at up to 500–750 μm of distance from the main canal

15. 4. ERBIUM YAG AND ERBIUM CHROMIUM LASERS T he erbium YAG laser (2,940 nm) [first and then the erbium, chromium YSGG laser (2,780 nm) were introduced in dentistry with the idea of substituting the drill for caries removal. The Er:YAG laser has a solid active medium, a crystal of yttrium, aluminum, or garnet, doped with erbium atoms. Erbium is a silver metal of the group of rare heart elements (Er, atomic number of 68) The Er,Cr:YSGG laser also has a solid active medium, a crystal of yttrium, scandium, gallium, and garnet (YSGG), doped with atoms of erbium and chromium

16. 4. ERBIUM YAG AND ERBIUM CHROMIUM LASERS The photothermal effect of erbium lasers produces vaporization of the smear layer and a certain grade of ablation and decontaminating effect that are however limited to the dentin canal surface (up to 250–300 μm in depth) , where laser energy is mainly absorbed and where it produces a direct photothermal effect.

17. 4. ERBIUM YAG AND ERBIUM CHROMIUM LASERS The affinity of erbium lasers with water explains the activation and agitation of the irrigant solution ( NaOCl ed EDTA). Tridimensional streaming of irrigants through the endodontic system (LAI and PIPS techniques), and their effect on bacteria decontamination, on debris and smear layer removal, via an indirect laser action. The great presence of water in the oral soft tissues; in the hard dental tissue, such as the enamel and the dentin; and much more in the carious tissue explains the extensive use of erbium lasers in dentistry. 

18. 5. CO2 LASER CO 2  far-infrared lasers (9,300–10,600 nm) were the first to be studied and used in endodontics for the decontamination and fusion of the apex in endodontic surgery  Advantages of the CO2 laser • less or no bleeding, resulting in a dry surgical field • reduction of surgical time due to better visibility • reduced swelling • reduced pain due to the fact that superficial nerve endings are coagulated • less or no sutures, resulting in shorter treatment time • less scaring. It was reported the use of the CO2 laser was unfavourable because of the loss of the odontoblastic layer

19. Properties of Laser Light

20. Components of Laser

21. Photons, emitted by the excitement of the active medium (stimulation), are reflected inside the optical cavity and pass through the active medium many times, amplifying their energy The active medium can be solid, liquid, gas, or a semiconductor (diode) and determines the specific wavelength of different lasers; its name identifies different lasers

22. Source of energy is usually represented by an electric coil or a diode laser or a flash lamp. Controller is a microprocessor that verifies the characteristics of the production of laser energy, the laser emission mode (continuous wave, mechanically interrupted or pulsed) The cooling system is necessary to dissipate the heat produced during the pumping process There are various systems of delivery , depending on the difference of the wavelength carried: optic fiber, hollow fiber, and the articulated arm

23. The ideal handpiece should be small, lightweight, and handy. Some handpiece does not have any terminal tip, but a reflecting mirror which works at a distance from the tissue (tipless or noncontact or far-contact handpiece)

24. LASER PARAMETERS LASER EMISSON MODE 1.Continuous Wave and Gated Mode 2. Free-Running Pulsed Mode 3. Pulse Duration and Pulse Repetition Rate

25. LASER POWER LASER EMISSON MODE 1.Continuous Wave and Gated Mode 2. Free-Running Pulsed Mode 3. Pulse Duration and Pulse Repetition Rate

26. OPERATOR MODALITY Operator modality of the clinician includes distance from the target, angulation of the irradiation, speed of the movement, and time of irradiation. Distance from the target influences energy density and power: when the distance between fiber and tip of the laser increases, the density of emitted energy decreases, enlarging the size of the spot

27. Laser-Tissue Interaction in Endodontics • Reflected • Absorbed • Diffused • Transmitted Reflection is an optical phenomenon due to the lack of affinity and absorption of light from the target, which, once hit, rejects the light completely Absorption : It is the expression of high affinity between light and the target which retains light in the point of irradiation. Diffusion depends on the capacity of the light to spread irregularly deeper into the target. The portion of laser energy which diffuses into the tissues is responsible for the therapeutic effects of some wavelengths

28. Transmission is the passage of light through a body or tissue, in the absence of interaction with it and, in consequence, without producing physical or biological effects

29. Laser Effects in Endodontics

30. PARAMETERS INFLUENCING LASER ENDODONTICS Continuous Wave Mode Diode lasers emit the energy in continuous wave ( cw ). The power higher than 1.5 W, the continuous emission in the root canal is inadvisable because of the excessive thermal damage released on the canal’s walls Therefore Chopping or Gating of emission is important as it produces more or less thermal effect . Short duration of t on , of 10–20 ms , is correctly and effectively used in endodontics with diode lasers at a power ranging from 2 to 3 W

31. 2.Pulse Repetition Rate The more frequent the repetition is, the shorter the time for thermal release is and the greater the thermal effect on the tissue is Repetitions of pulse (5–10 Hz/ pps ) allow a longer time for thermal relaxation and more control of tissue irradiation 3 . Fluence and Power Density It depends on the diameter of the tip used and of the irradiated square surface; For the same amount of energy and power emitted, larger is the diameter of the fiber or the irradiated surface, and lower is the density of power and energy.

32. 4. Pulsed Mode and Pulse Duration Short duration of pulse permits to control the side effects of thermal emission; when the energy is concentrated in a short time 5. Distance Between Target and Fiber When the distance between the target and fiber/tip of the laser increases, the density of emitted energy decreases, enlarging the size of the spot due to the effect of a certain grade of emission divergence and increasing the necessary amount of energy for the interaction

33. LASER TECHNIQUES USED IN ENDODONTICS

34. 1.CONVENTIONAL LASER ENDODONTICS The fiber is positioned in a dry canal 1 mm shorter from the apex and is retracted with helical motion in an established time (2 mm/s) Olivi (2013)

35. It requires the use of fibers or tips with a thin (narrow) diameter (generally 200–300 microns ) that are flexible and resistant to negotiate the anatomical curvatures of dental roots with minimal risk of breakage. It requires helical (circular) movement of the fiber , in order to increase the irradiation angle between laser fiber and dentin surface It is suitable for most wavelengths used in dentistry, in the visible (532 nm) , in the near-infrared (from 810 to 1340 nm), and medium-infrared (2780 and 2940 nm)

36. MECHANISM OF ACTION

37. IN ACCESS CAVITY PREPARATION The access to the pulp chamber can be performed with erbium lasers It is able to remove all the hard and soft dental tissues: enamel, dentin, carious tissue, and pulp without contact The following are the suggested energy setting to progressively use on enamel, dentin, carious tissue, and pulp A study by Hibst et al. (1996) demonstrated that bacteria are killed during cavity preparation up to a depth of 300–400 microns, under the irradiated surface

38. FOR ROOT CANAL PREPARATION

39. FOR ROOT CANAL PREPARATION Parirokh et al. (2007), in their in vitro study, concluded that 808 nm diode laser produced closure of the dentinal tubules of the irradiated surface in every condition of use and especially at the level of the apical third

40. SEM Images of Dentinal tubules irradiated with 810 nm diode laser at 2.5 W in gated mode (20 ms on and 20 ms off) with 200 micron tip, in root canal irrigated with 5 % NaOCl (2 mm/s speed

41. ROOT CANAL IRRIGATION The first lasers to be used in wet canals with water or irrigants were the Er:YAG laser and the Er,Cr:YSGG laser and later the near-infrared laser

42. 2. LASER ACTIVATED IRRIGATION 2.1 Wavelengths and Target Chromophore Matsumoto et al. (2011) and Gregorcic et al. (2012) described, through in vitro visualisation studies ( Er:YAG and Er,Cr:YSGG ), these two wavelengths are currently the only two capable of being extensively absorbed by different irrigant solution The experience of the authors, the 810 and 940 nm diode laser or neodymium:YAG laser (1064 nm) does not induce cavitation effect

43. Water absorption coefficient and penetration depth of different wavelengths

44. Bubble Formation and Collapse: Expansion and Implosion of Vapour Bubbles in Water The first effect of the absorption of erbium laser in water is a thermal effect an instantaneous superheating of the irrigant to the boiling point of water (100 °C) an initial vapour bubble which expands at the tip of the fibre and ends with consecutive implosion This mechanism had been previously referred to as “the Moses effect in the microsecond region” by van Leeuwen et al

45. Collapse of the laser-induced bubble follows immediately after the expansion. The shrinkage creates a cavitation-generated pressure wave that travels at supersonic speed ( shock wave ) in the beginning and at sonic speed ( acoustic waves ) later a highspeed liquid jet is formed fluid surrounding the bubble quickly flows inside the decompressed vapour gap, inducing fluid velocities of several metres per second

46. 2. HYDRODYNAMIC CAVITATION Cavitation is defined as “ the formation of an empty space (bubble) and fast collapse of a bubble in a liquid” The process is very fast and evolves mainly in the range of 100 μs –1 ms . When a bubble collapses, primary cavitation is formed, followed by secondary cavitation bubbles that create highspeed fluid motions in the canal The primary and secondary cavitation bubbles create microjets in the fluid that generate high forces and shear stress along the dentin walls sufficient to remove smear layer and biofilm

47. Effect of Tip Design 1. Conventional laser tips and fibres are flat-end fi ring so that no energy is directed laterally. 2. Today tips are available with different designs such as conical shaped, tapered and tapered and stripped (PIPS™), thereby allowing more energy to be delivered laterally and less frontally 3. Tips allow for lateral diffusion of the energy in the irrigant fl uid , decreasing the frontal pressure and improving the safety of the procedure

48. The flat laser generated an oval bubble, long and almost elliptically shaped due to the frontal emission of energy. The use of a conically shaped tip resulted in the formation of a round bubble due to the three- dimensional (frontal and lateral) emission of the energy

49. TIP POSITION In order to prevent extrusion, the laser fibre /tip should be kept away from the apex. At present there are two approaches: the one moving or keeping the fibre tip stationary in the root canal and the other using the fi bre tip stationary in the pulp chamber .

50. LAI advocates positioning the tip inside the canal filled with irrigant . The different techniques proposed for laser- activated irrigation: ( a ). 200–300 μm flat and conical tips are positioned stationary 5 mm from the apex ( b ). 280 μm flat tip at 1 mm short of the working length and moved it slowly up and down in the fi nal 4 mm of the apical third ( c ). conical tip inside the coronal one- third only (for 4 mm) slowly withdrawing it back to the pulp chamber ( d ). 300 μm flat tip inside the canal ( e ). 200 μm conical tip at the entrance of the orifice ( f ). 600 μm fl at tip in the chamber hovering over the orifice of the canal

51. Advanced Laser-Activated Irrigation: PIPS Technique and Clinical Protocol PIPS is an acronym fi rst described by Enrico DiVito (2006) and stands for photon-induced photoacoustic streaming Process by which photons of light are emitted at very low energy levels and with short microsecond pulse duration PIPS TM utilizes a unique tapered and stripped tip design that allows for lateral dispersion and propagation of the generated shock wave in liquids

52. PIPS TM protocol has been confirmed by thousands of clinical trials and differs from the other investigated LAI techniques in the following way: It uses a specific and unique tip design It uses sub ablative or minimally ablative energy. It is delivered via a very short pulse duration thus producing a very high peak power. It requires an easy positioning of the tip in the pulp chamber only and not into the canal. 5. It advocates minimal root canal and apical preparation .

53. 6.It is based on new “minimally invasive” or “biomimetic” concept 7.It minimizes the use of intracanal instrumentation without compromising the ability for irrigation to effectively reach all aspects of the root canal system 8. Photon-induced photoacoustic streaming (PIPS TM ) uses a cutting-edge erbium:YAG laser technology (2940 nm) at high peak power to pulse extremely low energy levels of laser light to generate photoacoustic shock waves into liquid filled root canals

54. Clean delta at the apical one-third of root canal seen after PIPS. Thermal damage is avoided because PIPS does not require that its tip be placed into the canal preparation at all but rather stationary in the coronal pulp chamber only Ledging and thermal damage on root canal surface as a result of Er,Cr:YSGG laser radial tip placed into the canal as advocated with conventional protocol

55. Sequential still frame shots showing the bubble cycle with increase ( a PIPS tip before activation, expansion from b – g ) and subsequent decrease (collapse from h – n ) of the bubble resulting in primary and secondary cavitation, seen from the PIPS tip during fluid activation at 20 mJ and 50 μs pulse duration

56. Effects of PIPS 1. On Vapour Lock: Chemical reaction of sodium hypochlorite produces free chlorine ions, specifically the hypochlorous acid (HO Cl) and the hypochlorite ion ( OCl − ) PIPS pressure waves to eliminate vapor lock from inside the artificial canal model 2. On Intracanal Tissue, Debris and Smear layer: A recent study from Arslan et al. (2014) compared the efficacy of PIPS technique and 1 % NaOCl with conventional, sonic, and ultrasonic irrigation on the removal of apically placed dentinal debris from an artificial groove created in a root canal. PIPS resulted in signifi cantly more effective removal of dentinal debris than conventional irrigation ( p < 0.001), sonic irrigation ( p < 0.001), or ultrasonic irrigation ( p = 0.005) [

57. 4 The final step before obturation requires patency to be confi rmed using .06 or .08 fi le after NaOCl irrigation activates by PIPS The final step before obturation requires patency to be confirmed using .06 or .08 file after NaOCl irrigation activates by PIPS

58. PIPS final irrigation protocol utilizes 17% EDTA activated by PIPS TM for 30s; after 60s resting time, sterile distilled water agitated by PIPS is used for 30s to inactivate the EDTA; Fnally three cycles of 5–6 % NaOCl are activated by PIPS for 30s; each cycle has 30s rest phase to allow the hypochlorite to react. Again sterile distilled water agitated by PIPS is used for 30s to inactivate the oxygen before obturation using resin-based sealer

59. PHOTO ACTIVATED DISINFECTION (PAD) 1.It is also known as aPDT . When microorganisms are the targeted cells, PDT is referred to as photodynamic antimicrobial chemotherapy (PACT) 2.It involves the use of a dye (photosensitizer) in combination with (laser) light to selectively kill cells. These cells can either be diseased cells, malignant or pathogenic cells or microorganisms 3. PAD application requires three fundamental elements • A photosensitizer • A light source • Tissue oxygen

60. MECHANISM OF ACTION OF PAD ,

61. The reactive oxygen species (ROS) resulting from both pathways mediate cellular damage. Amongst the ROS, singlet oxygen plays a central role for cytotoxicity in PAD, The greater the amount of singlet oxygen the target is exposed to, the more effectively bacteria are killed In order to reach the photosensitizer in situ, the penetration depth of the light is also important. Therefore, the wavelengths have to fall within the so called “ therapeutic window ” of the electromagnetic spectrum between 635 and 1000 nm , the area with the maximum penetration of light into the tissues.

62. Type I and II reactions require sufficient oxygenation of the target area. This might not be the case in the anaerobic environment found in primary root canal infections

63. 1. LASER IN ANALGESIA The pulsed Nd:YAG laser is widely used as a analgesia in endodontics.Its wavelengths interfere with the sodium pump mechanism, change cell membrane permeability, temporarily alter the nerve endings of sensory neurons and block depolarization of C and A nerve fibers. Laser analgesia is a  non-invasive, non-destructive, and non-thermal bio-modulating technique  with the ability to reduce or suppress painful sensations; it is obtainable in a low-energy-level irradiation form.

64. 2. PULPAL DIAGNOSIS A) LASER DOPPLER FLOWMETRY Non-invasive method used to assess blood flow in micro vascular systems. This method uses Helium Neon and diode lasers at a lower power of 1 or 2 Mw , b ased on Doppler principle to measure the blood flow in the pulp. MECHANISM OF WORKING

65. A beam of laser light is directed to the tooth surface through a fibre optic source Light enters the tooth and gets absorbed by red blood cells in pulpal capillaries leading to shift in frequency of scattered light. In moving blood cells their frequency shift according to Dopplers principle. This shift in frequency does not occur in light that is absorbed by stationary objects A proportion of doppler shifted light is detected with the help of a photodetector . Signal is then calculated with preset algorithm in LDF machine

66. B). THERMAL TESTING Pulsed Nd:YAG laser has been used and it shows better pulpal response than hot gutta percha . As a differential diagnosis between normal pulp, acute pulpitis and chronic pulpitis. Laser used - Nd:YAG at 2W, 20 pulses per sec ( pps ) at a distance of 10mm from the tooth surface. 4. Normal pulp - mild transient pain with in 20 to 30 sec and disappears in a couple of seconds after laser stimulation is stopped. 6. Acute pulpitis – pain induced immediately and continuous more than 30sec. 7. Chronic pulpitis – no pain or pain started after one min application and continuous more than 30sec.

67. 3.PULPCAPPING AND PULPOTOMY Since laser has the ability to coagulate and seal small blood vessels and leads to potentially bloodless field. The wound will be sterile after interacting with laser and will have an improved prognosis. No damage in the underlying laser ablated tissues has been found in studies using Nd:YAG and CO2 lasers. There was presence of secondary dentin and the odontoblasts layer was regular and not disturbed.

68. 4. IN OBTURATION   Argon, CO2 and Nd: YAG lasers have been used to soften gutta- percha and results indicate that Argon laser produces a very good apical seal. Thermo plasticised gutta percha system are one of the efficient methods in achieving a fluid- impervious seal. Softening of gutta percha has been attempted with CO2, Nd:YAG and Er:YAG lasers.

69. 5.ENDODONTIC RETREATMENT Rationale of using laser in non surgical endodontic retreatment may be ascribed to need to remove foreign material from root canal system which is difficult to achieve by conventional methods Nd:YAP (1340 nm) laser Neodymium doped yttrium aluminium perovskite laser used in root canal retreatment cases. Nd:YAG laser used to remove gutta percha and broken files from root canal.

70. LASER IN BLEACHING Whitening process achieved by chemical oxidation process. Lasers used for bleaching :- Carbon dioxide (10600 nm) Nd:YAG Argon (515 nm) Diode (980 nm) KTP (532 nm) KTP is Potassium titanyl Phosphate laser. Reducing agent + Oxidising agent Tooth Bleaching material Free reactive radicals react with unsaturated bonds Larger stain molecules converted into smaller ones Simple molecules are formed Reflect less light or become colorless Application of laser light generates heat Activates bleaching agent(fused silica+35%H2O2) H2O2 H2O+ O2 (nascent oxygen) Better penetration into enamel matrix 

71. TREATMENT OF INCOMPLETE TOOTH FRACTURE Lasers are used in repairing incomplete vertical fractures by causing fusion of the fracture. CO2 and Nd:YAG lasers have been unsuccessfully used to approximate fractured roots. INDICATIONS: Teeth with lateral canal leading to periodontal involvement. Teeth with pulp necrosis and purulent pulpitis. Teeth with periapical lesions upto 5mm or more. Teeth that has been treated at least 3 months with no success. CONTRAINDICATIONS : In advanced periodontitis cases. A deep crown and root fracture. Obliterated root canals in endodontic treated teeth.

72. REFERENCES  1) Nisha Garg, Textbook of Endodontics, 2nd edition. 2) Grossman, Endodontic Practice,13th edition. 3) Cohen, Pathways of Pulp, 10th edition. 4) Stabholz A et al. Lasers in endodontics. Dent Clin N Am 48 (2004) 809-832. 5) Nishad SG et al. Laser in Endodontics J Adv Med Dent Sci Res 2016;3(2):137-141. 6) Bansode PV et al. Lasers in Endodontics-A Literature Review. IOSR J Dent Medi Sci 2016; 15( 12 ) :87-91 . 7)Ratnakar P et al. Lasers in Endodontics- A beginning of new era. Indian J Stomatol 2010 :1(2);84-87

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