Laser in Conservative & Endodontics.pptx

Laser in Conservative & Endodontics

1. Laser in Conservative Dentistry & Endodontics Presented by: Dr. Vanitha v

2. Contents Introduction History Components of a typical laser Basic Principle of laser Laser Emission Modes Types of Laser Effects of laser Tissue - laser interactions Advantages and limitations Laser wavelengths used in dentistry Clinical applications of laser in conservative dentistry and endodontics

3. Introduction LASER is an acronym for L ight A mplification by S timulated E mission of R adiation. A device for generating a high-intensity, ostensibly parallel beam of monochromatic (single wavelength) electromagnetic radiation.

4. History Based on work of Gordon in 1955 & Schawlow and Townes (Bell Labs) in 1958, Theodore H. MAIMAN created the 1st operational laser on May 16, 1960 , a ruby laser emitting a brilliant red beam of light. 1961, Snitzer introduced Nd: YAG laser. 1971 Weichman and Johnson – introduced LASERS in Endodontics. 1977 first oral surgical application using CO 2 laser (Lenz et al, 1977)

5. History Dr. Terry Meyers and his brother William, an ophthalmologist, selected the Nd: YAG laser for experiments on the removal of incipient caries (Meyers, Meyers, 1985) . 1986 Zakirasen et al - Sterilization of Root Canals. Paghdiwala [U.S.A] in 1988, first time tested the ability of Er:YAG laser on dental hard tissue. 1987, FDA approved lasers usage in intraoral soft tissue surgery. 1998 Mazeki et al – Root canal shaping with Er:YAG laser.

6. COMPONENTS OF A TYPICAL LASER Optical Cavity This is an internally polished tube occupying the centre of the device.

7. 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: a. GAS - Argon, CO 2 b. CRYSTAL - Solid rods of garnet crystals grown with various combinations of Yttrium, Aluminium, Scandium and Gallium “doped’’ with Chromium or Erbium.

8. Solid State Semiconductor Wafers Multiple layers of metals like gallium, aluminium, indium, arsenide Lasers generally named after the active medium

9. 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. Diode laser

10. 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.

11. Reflective Mirror Partially transmissive mirror

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. Nd: YAG laser

13. Delivery System The laser light may be delivered by a quartz fiberoptic , a flexible hollow wave guide or a handpiece Waterplus handpiece and the laser tip

14. Control Panel This provides control over the power output

15. COMPONENTS OF A TYPICAL LASER

16. PROPERTIES OF LASER LIGHT Frehtzen and Koor , International Dental Journal, 1990

17. LASER EMISSION MODES Continuous Wave Emission Laser energy is emitted continuously as long as the laser is activated Pulse durations can range from tenths of a second to several hundred microseconds. E.g.: CO 2 and diode lasers

18. 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 E.g.: Nd: YAG, Er: YAG, Er, Cr: YSGG lasers

19. Gated pulse emission Periodic alteration of laser energy. By opening and closing of mechanical shutter in front of beam path of continuous wave. E.g.: Diode, CO 2 lasers

20. TYPES OF LASERS Based on wave length 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 Er, Cr: YSGG – 2,780 nm Er: YAG – 2,940 nm CO 2 – 10600 nm Near infrared Mid infrared Far infrared International Journal of Dental Clinics, 2011 Argon laser

21. Based on the Target Tissue Soft tissue lasers: Diode CO 2 Argon Nd: YAG. Hard tissue lasers: Er: YAG Er, Cr: YSGG International Journal of Dental Clinics, 2011 CO 2 and Argon laser

22. According to American National Standards Institute (ANSI) and Occupational Safety and Health Administration (OHSA) revised standards, 2007 lasers are classified as: Class I These are low powered lasers that are safe to view. This means the maximum permissible exposure (MPE) cannot be exceeded when viewing a laser with the naked eye or with the aid of typical magnifying optics (e.g. telescope or microscope). Class IM A Class 1M laser is safe for all conditions of use except when passed through magnifying optics such as microscopes and telescopes. Class 1M lasers produce large-diameter beams, or beams that are divergent. The Laser Institute of America, 2007:

23. Class II A Class 2 laser is considered to be safe because the blink reflex (glare aversion response to bright lights) will limit the exposure to no more than 0.25 seconds. Low powered visible lasers that are hazardous only when viewed directly for longer than 1.0 seconds, Class IIM Low powered visible lasers that are hazardous when viewed for more than 0.25 seconds. Warning label for class 2 and higher

24. Class III a Medium powered lasers that are normally hazardous if viewed for less than 0.25 seconds without magnifying optics. Class III b Medium powered lasers that are hazardous if the eye is exposed directly, but diffuse reflections such as those from paper or other matte surfaces are not harmful. Class IV These are high powered lasers which by definition, can burn the skin, or cause devastating and permanent ocular damage as a result of direct, diffuse or indirect beam viewing. These lasers may ignite combustible materials, and thus may represent a fire risk.

25. EFFECTS OF LASER ON TISSUES

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

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

28. 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

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

30. 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.

31. 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.

32. TISSUE INTERACTIONS WITH LASER Photo chemical Photo thermal Photo mechanical Photo electrical

33. In Photochemical reactions, very low-power irradiation inactivates cell function by means of induced toxic chemical processes. Certain wave lengths of laser are absorbed by naturally occurring chromophores and induce certain biochemical reactions. Bio-stimulation - stimulatory effect 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 Photo chemical interactions

34. Photo thermal interactions Photo ablation - the removal of tissue by vaporization and superheating of tissue fluids In photothermal reactions, laser light is absorbed by tissue chromophores and is converted to heat; this process is accompanied by a local temperature increase, and the heat is conducted to cooler regions. Greater degrees of heat result in denaturization, necrosis, and even vaporization or photopyrolysis or the burning away of tissues and spallation (that is, splintering of the tissue). Type of thermal reaction depends on: a. Spot size b. Power density c. Pulse duration d. Pulse frequency e. Optical properties and composition of irradiated tissue

35. 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

36. 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

37. ADVANTAGES AND LIMITATIONS

38. 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 .

39. Limitations All lasers require specialized training and attention to safety precautions. No single laser can perform all desired dental applications

40. LASER WAVE LENGTHS USED IN DENTISTRY

41. Laser Wavelength (nm) Pulse emission Power (W) Target tissue Applications Argon 488 Continuous 1-20 Soft tissue Curing composite resin Coagulation of vascular lesion Nd: YAG 1064 Free running 50-100 Soft tissue Coagulation Cutting – gingivectomy, frenectomy Diode 800-830 Continuous wave, Free running 50-100 Soft tissue Soft tissue pathology removal Cutting Erbium 2780-2940 Free running 3 Soft & Hard tissue Conservative & endodontic, Periodontal, excision & incision of soft tissue CO 2 10,600 Continuous 10-100 Soft tissue Excision of benign & malignant lesion Cutting

42. Clinical Applications Of Lasers In Conservative Dentistry & Endodontics

43. Heat test Pulp vitality Cavity preparation Indirect pulp capping Direct pulp capping Pulpectomy Bleaching International endodontic journal 2000

44. Access cavity preparation and orifice enlargement 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

45. Heat test Better pulpal response than hot Gutta Percha Pain response depends on: Enamel thickness Dentin thickness Pain threshold level Differential diagnosis -Between normal pulp, acute pulpitis, chronic pulpitis International endodontic journal 2000

46. 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

47. Cavity Preparation When used on hard dental tissues, the laser energy heats up the water within the hard tissue and cause that water to be turned into steam. This causes a mini-explosion to occur and the hard tissue is "ablated" (removed). ( Diaci et al 2012) This process happens in temperatures below the melting point of dental hard tissues (around 1200 o C) and varies according to the laser wavelength (e.g., Er: YAG reaches 300 o C at the ablation threshold, while Er, Cr: YSGG reaches 800 o C and CO 2 9.6 μm reaches 1000 o C) (Seka et al., 1996; Fried et al.,1996).

48. Laser cavity preparation in vitro

49. Laser cavity preparation in vivo

50. 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 CO 2 laser – with silver ammonium fluoride solution No post operative pain Indirect Pulp capping

51. 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 Indications- Pulp exposure less than 2mm No infection in the pulp Direct Pulp Capping

52. 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 is due to : Control of hemorrhage Sterilization Carbonization Lasers used - Nd: YAG, Argon laser, Diode laser, Er: YAG, CO 2 laser

53. Bleaching With Lasers Power bleaching is the term used for accelerated in-office tooth whitening procedures, using laser or Xenon plasma arc-curing light. Argon Laser Causes no thermal effect on teeth, so less dehydration of enamel. The treatment time is 10sec per application per tooth. It is the advantageous for clinician & patient.

54. Diode Laser It takes about 3 to 5 sec to activate the bleaching agent. Produces no heat during treatment.

55. Pulpotomy & Vital Pulp Amputation One of the most anticipated laser treatment in Endodontics Lasers used – CO2 laser Nd :YAG Ga -As laser Carbanized layer that is formed on the surface must be removed with 3% hydrozen peroxide and 5.25% of NaOCl Melcer et al, 1987 - first laser pulpotomy using CO 2 laser in dogs No damage seen in radicular portions of irradiated pulps Wound healing better than controls.

56. 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%

57. Pulpectomy and Root canal wall preparation Various laser systems emit energy that can be delivered into the root canal system by a thin optical fiber Ideal for straight and slightly curved canals Laser is used with air water spray Laser tip is placed 1mm short of the apex Apical region is shaped with files and reamers

58. 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

59. Cleaning and shaping CO 2 laser with Ag(NH 3 ) 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

60. Stabholz et al,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 )

61. 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

62. 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

63. The revolutionary PIPS®* method is employed, which uses the power of the Er:YAG laser to create non-thermal photoacoustic shock waves within the cleaning and debriding solutions introduced in the canal. The canals and subcanals are left clean and the dentinal tubules are free of a smear layer.

64. Obturation of root canals Obturation of the sterilized root canal is done with AH-plus and composite resin activated by Argon lasers Laser initiates photo polymerization by activation of composite resin Argon laser, CO 2 laser, Nd: YAG - soften the gutta percha Vertical compaction is a favorable method Argon lasers - good apical seal

65. 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

66. Lasers used for apicoectomy: Er: YAG laser Er, Cr: YSGG laser CO2 laser Sterilization of endodontic instruments Argon lasers CO2 lasers Nd: YAG lasers

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

68. Thank you…