LASERS IN ENDODONTICS....... Dr Jagadeesh Kodityala

lasers in endodontics

1. LASERS IN ENDODONTICS Dr. jagadeesh kodithyala 2 nd year p.g student Govt.dental college and hospital

2. Introduction Laser is an acronym for L ight A mplification by S timulated E mission of R adiation Laser is the brightest monochromatic light existing today After invention of laser it has found wide spread application in various fields like communication, industry, defense, and medicine Lasers are the single most important advancement in the field of Endodontics and they changed the ways in which many procedures can be done

3. HISTORY Albert Einstein - Stimulated Emission -Quantum Theory of R adiation. 1954’s, Bell Labs’ Arthur L. Schawlow & Charles H. Townes - MASER (microwave amplification by stimulated emission of radiation), by means of ammonia gas and microwave radiation. 1958, Schawlow & Townes - extending the MASER principle to the optical portion of the electromagnetic field - LASER (Light Amplification by Stimulated Emission of Radiation) was invented

4. May 16, 1960 - Theodore Maiman’s ruby laser - first working laser in history. 1960’s, Dr. Ali Javan - first gas laser with Helium Neon. 4 years later, 1964 - the CO 2 laser was successfully shaped by Kumar Patel

5. 1971 Weichman and Johnson – introduced LASERS in Endodontics . 1990, FDA approved lasers usage in intraoral soft tissue surgery. 1986 Zakirasen et al - Sterilization of Root Canals. 1998 Mazeki et al – Root canal shapin g with Er:YAG laser.

6. LASER PHYSICS

7. COMPONENTS OF A TYPICAL LASER OPTICAL CAVITY This is an internally polished tube occupying the centre of the device

8. Active medium This consists of chemicals that fill the core of the optical cavity , when stimulated the active medium emits laser light. The active medium may be: GAS - Argon, CO2 CRYSTAL – Solid rods of garnet crystals grown with various combinations of yittrium , Aluminium,scandium and gallium ‘’doped’’ with chromium, neodymium or erbium.

9. Solid state semiconductor wafers Multiple layers of metals like gallium, aluminium, indium, arsenide LASERS GENERALLY NAMED AFTER THE ACTIVE MEDIUM

10. EXCITATION SOURCE This surrounds the optical cavity and provides energy for exciting the active medium. This may be flash light, arc light or an electromagnetic coil.

11. Optical resonator This consists of two parallel mirrors placed at each end of the optical cavity. Laser light that is produced by the stimulated active medium is bounced back and forth in the optical cavity by these mirrors which amplifies the light beam.

12. Cooling unit Heat is generated as a by-product To dissipate this heat, air or water – assisted coaxial coolants are provided in the unit

13. Delivery system The laser light may be delivered by a quartz fiberoptic , a flexible hollow wave guide or a handpiece

14. Control panel This provides control over the power output

15. BASIC PRINCIPLES OF LASER

16. Reflective Mirror Partially transmissive mirror

17. Radiation International Endodontic Journal, 33, 173–185, 2000

18. LASER EMISSION MODES laser energy is emitted continuously as long as the laser is activated Some times these lasers have a mechanical shutter to produce a gated or super pulsed energy. Pulse durations can range from tenths of a second to several hundred microseconds. Eg : CO 2 , and diode lasers Continuous wave emission

19. Free running pulse emission Very short bursts of laser energy is emitted due to the flash lamp pumping mechanism. The pulse durations are hundreds of microsecond and there is Relatively long interval between pulses Eg : Nd:YAG , Er:YAG , Er,Cr:YSGG lasers

20. Types of lasers Based on wave length Emit visible light – 488 nm, 514 nm – argon laser Diode laser – Al Ga As – 800 – 830 nm Ga As - 904 nm In Ga As – 980 nm Nd:YAG-1064 nm Near infrared

21. Er,Cr:YSGG – 2,780 nm Er:YAG – 2,940 nm CO 2 – 10600 nm – Far infrared Mid infrared

22. Based on the target tissue where they are effective Soft tissue lasers – diode, CO 2 , Argon, and Nd:YAG . Hard tissue lasers – Er:YAG , Er,Cr:YSGG

23. According to ANSI and OHSA standards lasers are classified as: Class I These are low powered lasers that are safe to use, e.g. Laser beam pointer Class II Low powered visible lasers that are hazardous only when viewed directly for longer than 1000 seconds, e.g. He–Ne lasers. Class IIb Low powered visible lasers that are hazardous when viewed for more than 0.25 seconds.

24. Class IIIa Medium powered lasers that are normally hazardous if viewed for less than 0.25 seconds without magnifying optics. Class IIIb Medium powered lasers that can be hazardous if viewed directly. Class IV These are high powered lasers (>0.5W) that produce ocular skin and fire hazards.

25. Reflection results in little or no absorption, so that there is no thermal effect on the tissue.

26. Transmission of light transfers energy through the tissue without any interaction and thus does not cause any effect or injury.

27. When scattered, light travels in different directions and energy is absorbed over a greater surface area, producing a less intense and less precise thermal effect

28. when absorbed, light energy is converted into thermal energy

29. The term focused and defocused refers to the position of the focal point in relation to the tissue plane. The laser beam can be focused through a lens to achieve a converging beam, which increases in intensity to form a focal spot or hot spot, the most intense part of the beam. Past the focal spot, the beam diverges and the power decreases

30. When working on tissue, the laser should always be used either with the focal point positioned at the tissue surface or above the tissue surface. The laser should never be positioned with the focal spot deep or within tissue as this can lead to deep thermal damage and tissue effects.

31. Laser effect on tissues The light energy from a laser can have four different interactions with the target tissue. Photo chemical interaction. Photo thermal interaction Photo mechanical interaction Photo electrical interaction

32. certain wave lengths of laser are absorbed by naturally occurring chromophores and induce certain biochemical reactions Bio-stimulation, - stimulatory effects of laser light on biochemical and molecular processes that induce healing and repair of tissues. Photodynamic therapy- which is the therapeutic use of lasers to induces reactions and produce biochemically reactive form of oxygen This oxygen disrupts the membrane of micro-organisms Eg : tolonium chloride 635nm laser oxygen Photo chemical interactions

33. Photo thermal interactions Photo ablation- , or the removal of tissue by vaporization and superheating of tissue fluids Coagulation and hemostasis . Photopyrolysis or the burning away of tissues Type of thermal reaction depends on the Spot size Power density Pulse duration Pulse frequency Optical properties and composition of irradiated tissue

34. Non thermal interactions produced by high energy short pulsed laser light Photo-disruption – shock waves by laser –rupture the intermolecular and atomic bonds Photo-disassociation - which is the breaking apart of structures Photo-acoustic interactions- shock wave explode or pulverize the tissue, produces a crater Photo mechanical interaction

35. Photo plasmolysis , tissue is removed through the formation of electrically charged ions and particles that exist in a semi-gaseous, high-energy state. Photo electrical interactions

36. Absorption and transmission – depends on wavelength of laser Laser causes zones of carbonization, necrosis and induce cracks in the enamel Steam pressure build up in the dental tissues and explosive expansion takes with in the surrounding hydroxyapatite This process leads to surface holes or craters on the surface and hydroxyapatite has been vaporized This thermo-mechanical effect is very efficient in removal of hydroxyapatite in hard tissues Laser and hard tissue interactions

37. To prevent the pulpal damage by thermal effects of laser air water spray is used It produces Cooling effect on dental pulp Wash away the debris Keeping the area moist Prevents drying of tissues

38. Advantages and Limitations

39. Advantages Reduced need for anesthesia Greater comfort during and after surgery. Haemostasis and reduced risk of blood borne pathogens High patient acceptance Reduced stress and fatigue for the practitioner and staff. Produce less collateral thermal damage than with an electrocautery .

40. Limitations All lasers require specialized training and attention to safety precautions. Slower than traditional methods. No single laser can perform all desired dental applications

41. LASER WAVE LENGTHS USED IN DENTISTRY

42. CO 2 LASER: -gas active medium laser - hollow-tube like wave – guide -continuous or gated pulse mode or pulsed mode -Wavelength – 10,600 nm. -Well absorbed by water

43. Rapid soft tissue remover and has a shallow depth of tissue penetration, which is important when treating mucosal lesions. Beam can be focused to create a precised coagulation of small blood vessels Principle: CO 2 + energy CO+O ‾ Resulting molecule no longer able produce the CO 2 laser. This degrading nature of CO 2 brought several developments in the CO 2 laser system

44. Especially useful for cutting dense fibrous tissue. -Focused onto the surgical site in a non-contact fashion. -Loss of tactile sensation is disadvantageous, but the tissue ablation can be precise with careful technique. Laser systems Flowing gas CO2 system Sealed tube free space CO2 laser system Radio frequency wave guide CO2 laser system

45. -Has a solid active medium, a crystal of yttrium – aluminium – garnet doped with neodymium. -Wave length -1064nm -Fiber optic delivered in a free running pulsed mode . -Most often in contact with the tissue. -First laser designed exclusively for dentistry. -Highly absorbed by pigmented tissue and is about 10,000 times more absorbed by water than an argon laser. -Common clinical applications are for cutting and coagulation of dental soft tissues with good hemostatic capability. Nd:YAG

46. Er , Cr:YSGG and Er:YAG Er,Cr:YSGG (2790 nm) has an active medium of a solid crystal of yttrium – scandium-gallium-garnet that is doped with erbium and chromium. Er:YAG (2940 nm) has an active medium of a solid crystal of yttrium-Al-Garnet that is doped with erbium. -Both are delivered fiber optically in the free running pulsed mode.

47. The fibers are air-cooled and have a larger diameter than the other lasers mentioned, making the delivery system somewhat less flexible. -They have the highest absorption in water of any dental wave length and have a high affinity for hydroxyapatite . -These lasers are ideal for caries removal, root canal preparation and tooth preparation when used with a water spray.

48. ARGON LASER - Argon lasers have an active medium of argon gas that is fiberoptically delivered in continuous –wave and gated – pulse modes. - Two emission wavelengths, and both are visible to the human eye 488nm (blue in color) and 514 nm (blue – green) - Both wavelengths are not well absorbed in dental hard tissues and are poorly absorbed in water. - can be used as an aid in caries detection. The diseased, carious area appears as dark orange-red color and is easily discernible from the healthy structures.

49. Ho: YAG Has solid active medium, a crystal of Y.A.G. doped with Holmium. - Fiberoptically delivered in contact with the tissue in free-running pulsed mode. -Wavelength – 2120 nm. -Ho laser has little affinity for pigmented tissue; its hemostatic ability is decreased because of its lower absorbency into hemoglobin and other similar pigments. -Absorbency by tooth structures is low. -Frequently used for arthroscopy surgery on the TMJ .

50. Diode -Have a solid active medium; it is a solid-state semi conductor laser that uses some combination of Al, gallium and arsenide to change electric energy into light energy. -Wave length range from 800-980nm

51. -Laser energy is delivered fiberoptically in continuous-wave and gated – pulse mode; used in contact with the tissue. -Poorly absorbed by tooth structure so that soft tissue surgery can be performed safely in close proximity to enamel, dentine and cementum . -An excellent soft tissue surgical laser indicated for cutting and coagulating gingiva and mucosa and for soft tissue curettage, or sulcular debridement.

52. Clinical Applications Of Lasers In Endodontics

53. Heat test Pulp vitality Indirect pulp capping Direct pulp capping Vital pulp amputation Access cavity preparation and orifice enlargement International endodontic journal 2000

54. Pulpectomy Root canal preparation with lasers Debris removal at apical foramen Sterilization and disinfection of infected root canals Closure of apical foramen Endosurgery International endodontic journal 2000

55. Heat test Instead of hot GP Better pulpal response than hot GP Pain response depends on Enamel thickness Dentin thickness Pain threshold level International endodontic journal 2000

56. Differential diagnosis -Between normal pulp, acute pulpitis , chronic pulpitis Laser used - Nd:YAG at 2W, 20 pulses per sec ( pps ) at distance of 10mm from the tooth surface Normal pulp- mild transient pain with in 20 to 30 sec and disappears in a couple of seconds after laser stimulation is stopped Acute pulpitis – pain induced immediately and continuous more than 30sec Chronic pulpitis – no pain or pain started after one min application and continuous more than 30sec International endodontic journal 2000

57. LASER DOPPLER FLOWMETRY: LDF was developed to assess blood flow in micro vasculature Ex: in retina , gut mesentery , renal cortex & cortex. He-Ne laser - 632.8 nm , which when scattered by moving red cells , under went a frequency shift according to the Doppler principle .

58. Advantages : It reflects vascular rather than nervous responsiveness recent trauma or following orthognathic surgery

59. Limitations : Difficult to obtain laser reflection from certain teeth. Differences in sensor output and inadequate calibration by the manufacturer may dictate the use of multiple probes for accurate assessment. Values may vary i.e sometimes may not be reliable indicator due to problems a. changes in red cell flux in gingival tissue b. changes in ambient light intensity c. movement artifacts.

60. In cases of deep and hypersensitive cavities A reduction in the permeability of the dentin- achieved by sealing the dentinal tubules Lasers used Nd : YAG – 2W & 20 PPS for less than one sec with black ink CO2 laser – with silver ammonium fluoride solution No post operative pain Indirect Pulpcapping :

61. Bloodless field Sterilization of the treated wound According to Paschoud and Holz , 1988 laser treatment causes direct stimulation of dentin formation Melcer also described successful pulp restoration after direct capping of inflamed pulps with laser irradiation Direct Pulp Capping

62. Indications - Pulp exposure less than 2mm No infection in the pulp Procedure – 1 or 2 W laser energy after alternate irrigation with 5.25% NaOCl and 3% Hydroen peroxide Exposure site closed with Calcium hydroxide paste Success rate 89% due to Control of hemorrhage Sterilization Carbonization Lasers used - Nd : YAG, Argon laser, Diode laser, Er : YAG, CO2 laser

63. Pulpotomy & Vital Pulp Amputation One of the most anticipated laser treatment in Endodontics Lasers used – CO2 laser 1 to 4 W Nd :YAG for 2sec, Ga -As laser Carbanized layer that is formed on the surface must be removed with 3%hydrozen peroxide and 5.25% of NaOCl Shoji et al 1985 -first laser pulpotomy using CO 2 laser in dogs No damage - radicular portions of irradiated pulps Wound healing better than controls.

64. Wildar - Smith et al 1997 and Dang et al 1998 found CO 2 laser pulpotomy to be very successful -teeth with large exposure sites, subjected to bacterial contamination for several days. Wound healing – one week Dentine bridge- 4 to 12 weeks Success rate – 50%

65. Pulpectomy and Root canal wall preparation Various laser systems emit energy that can be delivered into the root canal system by a t hin optical fiber Straight and slightly curved canals Laser with air water spay Laser tips placed 1mm short of the apex Apical region is shaped with files and reamers

66. The potential bactericidal effect of laser irradiation can be used effectively for additional cleaning of the root canal system following biomechanical instrumentation Access cavity preparation Er:YAG – 8Hz, 2W Pulpectomy – Nd :YAG for 2W at 20PPs for one sec, Multiple application with 5 sec interval

67. Cleaning and shaping CO2 laser with Ag(NH3)2 F of 9.3 to 10.49 μ m- effectively seals dentinal tubules Nd:YAG laser with black ink Argon lasers Er:YAG - most effective KTP – Potassium titanyl phosphate 532nm removes smear layer and debris

68. Nd:YAG laser 532nm – nanosecond pulsed, frequency doubled Xenon chloride ( XeCl ) laser – 308nm seal the exposed dentinal tubules Ar -Fluoride excimer laser- 193nm removes peritubular dentine, melting and resolidification of dentinal tubules Ho:YAG laser – 2.10 μ m – ablation of dentine and for cutting the dentin Nd:YAP –( Nd : Yttrium Aluminum Perovskite ) 1340nm – effective in root canal preparation and retreatment Free electron laser (FEL) – 2-10 μ m – hydroxyapetite crystals effected

69. Stabholz and Colleagues 2003 developed a new endodontic tip that can be used with an Er:YAG laser system The beam of Er:YAG laser is delivered through a hollow tube to allow lateral emission of the irradiation (side-firing)

70. This new endodontic side firing spiral tube (RC Lase ) was designed to fit the shape and volume of root canal prepared by Ni-Ti rotary instruments. Emits radiation laterally to the walls of the root canal through a spiral split The tip is sealed at its far end Limitations of lasers in cleaning and shaping The laser energy from the tip is directed along the root canal and not necessarily laterally to the root canal wall. Thermal damage to the periapical tissues

71. Sterilization of infected root canals Effective tools for killing micro-organisms by its bactericidal effect Disinfection depends on Laser wavelength and energy characteristics Lasers used Pulsed Nd:YAG laser 2W, 20PPS with silver ammonium fluoride solution for 5 sec – 80 to 90% sterilization Argon lasers Diode lasers- 810nm CO2 lasers Er:YAG laser Nd:YAP laser 1.34 μ m Xe-Cl lasers – 308 nm

72. Photo-activated disinfection Less toxic and alternative to chemical disinfection It is an combination of photosensitizing dye and a laser of specific wavelength Kills high population of bacteria It destroys collagen, and carious dentin

73. Two components PAD solution: Tolonium Chloride Save Dent Laser -635 nm Mechanism of action: Photosensitiser Reactive Oxygen sp Disrupts membrane

74. Advantages Ease of use Disinfection Duration -1-2 min Toxicity Does not affect fibroblasts or Keratino cytes Laser is safe

75. Obturation of root canals Obturation with AH –plus and composite resin activated by Argon lasers Laser initiates photo polymerization by activation of composite resin Argon laser, CO2 laser, Nd:YAG - soften the guttapercha – vertical compaction Argon lasers – good apical seal

76. Retrograde cavity preparation and prevention of micro leakage Retrograde cavity preparation Er:YAG laser – 8Hz & 2W Prevention of micro leakage Sealing of dentinal tubules Nd:YAG laser 1 or 2W under air water cooling in combination with silver ammonium solution CO2 laser

77. Endodontic Surgery Miserendino 1985 suggested that the rationale for laser use in endodontic periapical surgery should include : Improved haemostasis & concurrent visualization of the operative field Potential sterilization of the contaminated root apex Potential reduction of the permeability of the root surface dentin A reduction in post operative pain A reduced risk of surgical site contamination by eliminating the use of aerosol producing air turbine hand pieces for apicosectomy

78. Apicosectomy Er:YAG laser – root resection Er,Cr:YSGG laser CO2 laser Sterilization of endodontic instruments Argon lasers CO2 lasers Nd:YAG lasers Removal of calcified attached denticles Pulsed dye lasers -504nm

79. CONCLUSION A proper and successful use of lasers in Endodontics is depends on the understanding of characteristics and their limitations . Lack of understanding often leads to the misuse and abuse of lasers, causing detrimental results