laser in endo.pptx various types of lasers used in endo

Laser in endodontic procedure

1. Lasers In Endodontics and Conservative Dentistry Presented by- Mariya Kitabwala PG 2 nd year Department of Conservative dentistry and Endodontics Guided by- Dr. Suruchi Sisodia Mam(HOD) Dr. Mayur M. Kahate Sir (PROFESSOR) 1

2. contents Introduction History Mechanism of action Characteristics Classification Components of laser Lasers in pulpal diagnosis - LDF Lasers in vital pulp therapy Direct pulp capping Indirect pulp capping 2

3. Pulpotomy Apexogenesis Lasers in endodontics Traditional laser endodontics Photo-activated disinfection Laser-activated irrigation Root canal preparation Obturation Apical surgery Vertical root # diagnosis Endodontic retreatment Laser applications in Conservative Dentistry Caries detection using lasers 3

4. Caries removal Bleaching using lasers Etching and bonding using lasers Polymerization of composite resins by lasers Indications & Contraindications Conclusion References 4

5. INTRODUCTION Laser is an acronym for light amplification by stimulated emission of radiation. Light is a form of electromagnetic energy that travels at a constant velocity in the form of waves. The basic unit of light is termed photon, which means a particle of light. 5

6. Ordinary light, as produced by the sun or a table lamp, is a sum of many types of photons or light waves that are diffused and not focused. Photons are released when an atom in its ground state absorbs energy, gets excited, and moves to a higher energy state. The release of photon is spontaneous in nature and hence termed spontaneous emission. Light waves produced are noncoherent and polychromatic. 6

7. Two photons are released if additional quantum of energy is absorbed by an already excited atom. The energy is emitted, or radiated, as identical photons, traveling as a coherent wave. These photons can energize more neighboring atoms, which would emit additional identical photons, resulting in an amplification of light energy, producing a laser beam . 7

8. The generation of a laser beam requires an active medium containing a collection of atoms or molecules. The medium can be either a solid, liquid, or gas, contained in a ceramic or glass tube. Applying an electric current or a flash lamp energizes this medium, thereby starting a stimulated emission of radiation. Review Article- Role of laser in conservative dentistry and endodontics Mishra et al. / IP Indian Journal of Conservative and Endodontics 2022 8

9. When the atoms in the energized state become more in number than those in the ground state, a population inversion occurs. These photons can be directed with the help of mirrors This coherent, collimated beam of laser light can be delivered to the target tissue. 9

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12. 1971- Weichman and Johnsoon - First used laser in endodontics to seal apical foramen in vitro 1985- Shoji et al – Laser aided pulpotomy 1986- Zakariasan et al – Sterilization of root canal using lasers 1988- Misserendino – Apicoectomy using lasers 1994 – Morrita - Nd YAG laser in endodontics 1998- Mazeki et al – root canal shaping using Er:YAG laser 12

13. Properties of laser Characteristics Of Lasers : Monochromatic Unidirectional (Collimated) Coherent Pavithra Prabakaran. Laser Physics - An Insight. Jour of Clin Cas Rep, Med Imag and Heal Sci 4(5)-2023 13

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15. CLASSIFICATION OF LASERS Review Article- Role of laser in conservative dentistry and endodontics Mishra et al. / IP Indian Journal of Conservative and Endodontics 2022 15

16. BASED ON LIGHT ACTIVE MEDIUM Gas lasers: • Argon • Carbon-dioxide Liquid : • Dyes Solid: • Nd : YAG • Erbium: yttrium aluminum garnet (Er: YAG) Semiconductor: • Hybrid silicon laser • Diode Excimers : • Argon-fluoride • Krypton-fluoride • Xenon-fluoride 16

17. CLASSIFICATION OF LASERS BASED ON POWER • High power, warm, or hard laser • Lasers with moderate powers • Low level or cold lasers. CLASSIFICATION OF LASERS BASED ON WAVELENGTH • Ultraviolet (UV) range 300–400 nm • Visible light range 400–700 nm • Near-infrared (NIR) range 700–1200 nm • Far-infrared range more than 1200 nm. 17

18. Based on Clinical Applications 18

19. Based on Mode of action Contact mode (focused or non focused) Eg : He:YAG , Nd YAG Non contact mode Eg : CO 2 19

20. 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. 20

21. 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. 21

22. Based on Mode of emission Continuous wave Gated Pulsed mode Pulsed mode 22

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24. Basic Components of Lasers A laser is composed of several basic elements for the generation and emission of the laser beam. The principal elements of a laser are: • Optical resonator (or optical cavity) • Active medium • Source of energy (or pumping source) • Controller (or microprocessor) • Cooling system • Delivery system • Handpiece and tips Priya NK, Sowmya NK, Ashwini R, Madhushankari GS 29 . Lasers in Dentistry - Thinking a head. CODS J Dent 2014;6;102-7 24

25. Illustration of a gas or solid, active-medium laser, such as a carbon dioxide (CO 2 ) or Nd:YAG laser. Principles and Practices in Laser Dentistry- Robert A. Convissar 25

26. OPTICAL CAVITY It is a cavity which contains the active medium and two mirrors located at its extremities One completely reflective mirror and the other partially reflective and permeable. 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 via a waterfall phenomenon (amplification), before exiting (coming out from) the partially permeable mirror. 26

27. ACTIVE MEDIUM It is the heart of a laser 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 27

28. ENERGY SOURCE(PUMPING SOURCE) The pumping source excites the atoms of the active medium, producing the inversion of the population of electrons. This source of energy is usually represented by an electric coil or a diode laser or a flash lamp. The characteristics of the energy source are important for the generation of the laser pulse, especially for short-duration pulses (high peak power). 28

29. CONTROLLER SUBSYSTEM AND COOLER The controller is a microprocessor that verifies the characteristics of the production of - laser energy - laser emission mode (continuous wave,mechanically interrupted or pulsed) - pulse frequency of repetition (pulses per second or pulse repetition rate) - length of the emission of the single pulse The cooling system is necessary to dissipate the heat produced for the pumping process. 29

30. DELIVERY SYSTEM Once generated, laser light must be conducted to the point of use. There are various systems of delivery, depending on the difference of the wavelength carried: - optic fiber - hollow fiber - the articulated arm 30

31. Dubey PK, Shetty J, Kumar A, Dubey A. An insight into dental lasers delivery system. IJOCR 2015; 3 (3):64-67 . 31

32. Total Internal Reflection - The Basic Principle of Optical Fiber An optical fiber is comprised of a light-carrying core in the center, surrounded by a cladding that traps light in the core. Glass fiber is covered by a plastic buffer coating that protects it from the environment and allows easy handling for splicing. 32

33. There are 2 conditions necessary for TIR to occur- Refractive index of first medium should be greater than that of second medium (n1>n2) The angle of incidence must be greater than critical angle( i >c) Total internal reflection in optical fiber 33

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35. Commonly Used Lasers In Endodontics Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review, Bioengineering 2023 35

36. Lasers Used In Endodontics Lasers Wavelength (nm) Visible light Argon 488 – 514 KTP 532 Diode 635 – 675 Near infrared AlGaAs 800 – 830 GaAs 904 InGaAs 980 Nd:YAP 1,340 Nd:YAG 1,064 Mid infrared Er,Cr:YSGG 2,780 Er:YAG 2,940 Far infrared CO2 9300, 9600, 10600 36

37. The Near-Infrared Lasers (810 nm To 1340 nm) They have negligible affinity for water and the HA of hard dental tissues and have no ablative effect on dentinal surface. The thermal effect of the radiation penetrates up to 1 mm into the dentinal walls, allowing the decontaminating effect on deeper dentin layers as they are absorbed by the bacteria pigments. This allows for a bactericidal effect in deeper dentin layers Delivers laser energy through an optical fibre. 37

38. The Mid-Infrared Lasers (2780 nm And 2940 nm) They are primarily absorbed by water (and, to a lesser degree, HA) in the dentinal walls and consequently have a superficial ablative and decontaminating effect on the root canal surface Delivered with flexible, fine tips. 38

39. Far-Infrared Laser CO2 Laser (10,600 Nm) They has a strong affinity for water and especially hydroxyapatite. The inability of this wavelength to utilize a fiber -optic delivery system limits its utility in intracanal applications. 39

40. Diode Lasers Active medium – Semi-conductor Red visible spectrum : 635 – 675 nm Near infrared spectrum : 810 – 1,064 nm It was introduced in endodontics at the end of 1980s, for the treatment of dentin hypersensitivity. It is used for low-level laser therapy (LLLT) and also, for activation of bleaching system. 40

41. Nd:YAG Wavelength : 1064 nm Delivered fibre-optically. Has high affinity for water & pigmented tissues. It offers good haemostasis. Thus, used extensively in surgeries. Pavithra Prabakaran. Laser Physics - An Insight. Jour of Clin Cas Rep, Med Imag and Heal Sci 4(5)-2023 41

42. The emitted energy from the Nd:YAG laser is mainly scattered in the target tissues under the form of thermal energy. It is used in the free-running pulse mode so as to avoid the risk of phenomenon of summary accumulation of thermal energy & tissue damage. It is mainly used for root canal decontamination. 42

43. Er Family Lasers Er:YAG – 2,940 nm Er,Cr:YSGG – 2,780 nm Delivered using a solid optic-fibre. It uses a visible aiming beam (Red/Green) to provide good visibility & control of interaction with tissue. It produces high power in a free-running pulse mode. It produces photothermal effect which is used for Vaporization of smear layer Ablation & decontamination (250 – 300 µm depth) 43

44. Has high affinity for water (high absorption) & HA. So, can be used to remove caries & cut dentin with coolant. Can also be used on soft tissues. Therefore, it is also called “All-tissue laser”. Used in endodontics : Activation & agitation of irrigants LAI, PIPS Bacterial decontamination Smear layer & debris removal 44

45. Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review, Bioengineering 2023 45

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47. 47 Laser Parameters Energy The amount of energy emitted is calculated in Joule (J); normally each pulse energy ranges from few mJ (minimum 5 mJ ) up to hundred mJ (maximum 1000 mJ or 1 J). The measurement of the work completed over time is called power and is measured in Watts. One Watt equals 1 Joule delivered for 1 second, and the power can be selected by the operator on each device. LASER Physics& its Application in Dentistry – A Review Yeragi et al 2019

48. 48 2. Fluence and irradiance Irradiance is the intensity (power density) of the laser beam measured in W/cm2 and is inversely proportional to the square of the radius of spot size. for a given wave- length, thelarger thelaser beam diameter (spot size), the deeper the penetration. Fluence describes the energy per unit area for a single pulse. For a fixed beam diameter and pulse duration, fluence can be altered by changing the power of the laser or the exposure time

49. 49 3. Pulse duration (pulse width) The pulse width is the time during which the laser output power remains continuously above half its maximum value. If pulse duration is equal to or less than the thermal relaxation time of the target, then unwanted heat diffusion to adjacent tissue is reduced

50. 50 4. Pulse repetition rate Pulse repetition rate or pulse repetition frequency is defined as the number of emitted pulses per second (Hz). The minimum quantity of energy necessary to generate a clinical effect of ablation or vaporization is called “threshold of ablation.” Average power ( P ): expressed in Watt = E (J) × F (Hz or pps )

51. 51 LASER ROOM OPERATING CONDITIONS Location The room in which the laser is used is called a Controlled Area. It is recommended that only one patient be treated at any given time in the laser room. A sign must be fitted to the door of the room with the wording: CONTROLLED AREA –LASER The following notice must be fixed to the laser machine itself : This device must be used by an Authorized Operator only Minimum standard guidelines of care on inimum standard guidelines of care on requirements for setting up a laser room equirements for setting up a laser room Indian J Dermatol Venereol Leprol | July-August 2020

52. 52 2. DIMENSIONS Laser room has to accommodate patient chair (length 6 feet and width 2.5 feet), a trolley carrying the laser machine (about 3 feet x 3 feet), a cart carrying cooling device (about 2.5 feet x 2.5 feet), a laser operator and at least one assistant. The ideal dimension should be 12 feet by 12 feet. The room should allow free movement of operator for proper positioning of laser probes .

53. 53 3. Laser room door Door should be of 3 feet width for easy movements of laser machines with its trolley. The door should be made of opaque material. This is to prevent transmission of laser light. The lock should always have preferential access from inside to have uninterrupted exit in case of emergency. Laser warning sign to be fixed outside the treatment room

54. 54 Laser hazards and its safety Ocular Hazard: Potential injury to the eye can occur either by direct emission from laser or from the reflection from mirror-like surfaces. Dental instruments have been capable of producing reflections that may result in tissue damage to both the operator and the patient. Safety Precaution: The use of carbonized or non-reflective instruments is recommended during laser treatment to prevent damage to the non-target tissues. Patient, clinician, entire surgical team and any observers must wear protective eyewear specific for the wavelength of laser to be used Priya NK, Sowmya NK, Ashwini R, Madhushankari GS 95 . Lasers in Dentistry - Thinking a head. CODS J Dent 2014;6;102-7

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58. 58 2.Tissue Damage: Laser induced damage to the non-targeted tissue (oral and skin) can result from thermal interaction of radiant energy with tissue proteins. Temperature elevations of 21ºC above normal body temperature (37ºC) can produce cell destruction by denaturation of cellular enzymes and structural proteins, which interrupts basic metabolic processes. ◦ Safety Precaution: Laser use should be confined to controlled areas with restricted access. Non-targeted tissue or the delicate oral mucosa is protected from accidental laser beam through the use of wet clothes or gauze packs. Hard tissues are protected during the soft tissue surgeries using the silver foil in between gingiva and teeth. Use of protective laser curtains prevents the accidental exposures to spectators

59. 59 3.Plume Control: Laser procedures produces a smoke or plume generated through the thermal interaction of surgical lasers through tissue or through the accidental escape of toxic chemical, gases and micro-flora (fluorine, hydrochloride) from the laser itself. Safety Precaution: Standard high-speed evacuation chamber is adequate to control the smoke or plume as well as good quality masks should be worn by the clinicians

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61. 61 4.Combustion Hazards: Laser pose a significant combustion hazard in the presence of flammable objects like solids, liquids and gases used in dental surgical setting. Toxic fumes are released as a result of combustion of flammable materials. Safety Precaution: Should avoid the use of flammable and explosive liquid or gases in the operating room as laser energy generates heat. Flammable materials like surgical drapes and gauze sponges may be soaked in sterile saline to reduce the possibility of burning by accidental exposure to the laser beam. The use of flame-resistant materials like Poly Vinyl Chloride or red rubber or silastic intubation tube wrapped with aluminum sheet can be effective during soft tissue lasing.

62. 62 5.Electrical Hazards: Most laser systems involve high potential, high current electrical supplies leading to shock and explosion hazards. Safety Precaution: Safe manufacturing practices offer adequate protection from these hazards. Insulation, shielding, grounding and housing of high voltage electrical components provide adequate protection under most circumstances from electrical injury. The floor of the operating room must be kept dry while operating with laser unit

63. 63 6.Warning Sign: At or nearing the operating area, warning signs should be visible and clearly mentioned containing the words ‘Danger’ and ‘Laser Radiation. 7.Sharps: Scored laser tips of quartz fibers are sharps and need to be disposed properly.

64. Laser-tissue interaction Absorption Reflection Scattering Transmission Review Article- Role of laser in conservative dentistry and endodontics Mishra et al. / IP Indian Journal of Conservative and Endodontics 2022 64

65. Photobiologic effects when using a dental laser- Photo-Chemical Photo-Thermal Photo-Mechanical The target tissues are : Dentin Smear Layer Residual Pulp Bacteria In All Their Aggregate Forms 65

66. The three primary photothermal laser-tissue interactions are Incision/Excision- Laser beam in focus with small spot size 2. Ablation/Vaporization- Laser beam with wider spot size, will interact with tissues over wider area but more superficially. 3. Hemostasis/Coagulation- Laser beam out of focus Principles and Practices in Laser Dentistry- Robert A. Convissar 66

67. Principles and Practices in Laser Dentistry- Robert A. Convissar 67

68. PHOTOCHEMICAL : Photochemical effects occur when the laser is used to stimulate chemical reactions, such as the curing of composite resin. The breaking of chemical bonds, such as using photosensitive compounds exposed to laser energy, can produce a singlet oxygen radical for disinfection Produces activation of photosensitizers inoculated into the canals. This effect is responsible for antibacterial effect of the PAD. Certain biologic pigments, when absorbing laser light of a specific wavelength, can fluoresce, which can be used for caries detection on occlusal surfaces of teeth 68

69. PHOTOMECHANICAL : The pulse of laser energy on hard dentinal tissues can produce a shock wave, which is an example of the photoacoustic effect of laser light. This process is often called spallation. PHOTOTHERMAL (1°) + PHOTOMECHANICAL-PHOTOACOUSTIC : Activates the irrigants in PIPS. 69

70. Lasers In Pulpal Diagnosis 70

71. Abbas Kapasi , Fatema Kapasi , An Update on Low Level Laser Therapy Applications in Endodontics for Predictable Outcomes, Acta Scientific Dental Sciences (2019) 71

72. The vitality assessment of teeth is complicated by the fact that the dental pulp is enclosed within calcified tissue, and so most methods of assessing pulpal vitality do so indirectly. The reliability of conventional pulp tests can vary & particularly so if the teeth are newly erupted or have been traumatised. Tests like EPT and the thermal stimulation rely on the subjective responses by the pt & only measure the neurological status of the pulp, not the vitality. Laser Doppler Flowmetry is one of the current methods to assess the pulpal circulation. 72

73. Laser Doppler Flowmetry (LDF) 1 ST introduced by Yeh & cummins , 1964 Non-invasive, objective, painless, semi-quantitative, electro-optical technique. It is based on the changes in the RBC flux in the pulp tissue. Current Applications of Lasers in Endodontics Giornale Italiano di Endodonzia (2019 73

74. TECHNIQUE : A fibre-optic probe is placed against the tooth surface through which the laser beam is radiated. Upon contact with RBC in the target tissue, light waves are reflected & scattered. This light beam, when scattered by moving RBCs, undergoes a frequency-shift according to the Doppler principle . When the light beam is scattered off the stationary tissue cells , there is no shift in the light spectrum. 74

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76. The difference b/w the two frequencies gives a semi-quantitative measurement of the blood flow through the tissue. A photodetector receives the scattered beams back & convert to signal which calculate the magnitude of the pulpal flow called as Flux. [Arbitrary unit is Perfusion unit (PU) ] 76

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78. When the crown is not isolated, the periodontal tissues may contribute to the signal (80%) , so when measuring PBF, it is necessary to isolate the crown. Sensitivity to the movement requires that they are stabilised in an occlusal stent or a modified rubber dam clamp. 78

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81. The penetration depth of a LDF beam in teeth has been investigated. In extracted teeth, with various density of laser, laser light achieved approx. 4-6 mm depth of root densely and 13 mm depth less densely. In some teeth, the laser beam may even reach to apex. 81

82. Lasers Used : He-Ne laser at 632.8 nm Other wavelengths used : Semi-conductor laser : 780 nm 780-820 nm The 810 nm/3.1 kHz combination offered greatest sensitivity & specificity as a test to distinguish b/w root-filled & vital teeth. 82

83. INDICATIONS : 1. Estimation of pulpal vitality 2. Pulp testing in children 3. Differential diagnosis of apical radiolucencies 4. Understanding age-related changes 5. Monitoring of reactions to Local anaesthetic agents 6. Helps in comparing the reactions of thermal & electric signals 7. Understanding pulpal reactions during orthodontic treatment 8. To measure PBF after orthognathic surgery 9. Monitoring PBF after traumatic injuries 10. Monitoring revascularization of replanted teeth 83

84. CONTRAINDICATIONS : Teeth with vital apical pulp tissue. (Because LDF probes detect only coronal PBF) Difficulty in obtaining laser reflection in restored teeth because of insufficient transmission 84

85. ADVANTAGES : Less pain & patient discomfort. Based on objective findings rather than subjective patient responses. Low running cost after the initial purchase 85

86. DISADVANTAGES : Expensive. Technique sensitive. Sensitive to contamination from blood flow in adjacent tissues. Time consuming. Difficult to obtain laser reflection from certain posterior teeth. 86

87. JOE – MAY 2022:compared diagnostic accuracy including sensitivity,specificity , of cold pulp testing,heat pulp testn,ept,ldf,po Conclusion:ldf and po most accurate diag methods,hpt was least.ept showed high accuracy wen testing vital,low in non vital.cpt:moderate accuracy in vital and non vital 87

88. Lasers In Vital Pulp Therapy Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 88

89. .Laser application as an adjunct for VPT has been studied to explore its antibacterial, bio-stimulation, hemostatic, and wound healing actions and its ability to increase the expression of lectin and collagen The therapy varies depending on the degree of contamination of pulp tissue. Indirect Pulp Capping Direct Pulp Capping Pulpotomy Partial Pulpotomy Apexogenesis 89

90. 1. Deep Dental Caries Treatment of the deep dentin at the completion of cavity preparation is an important step for maintaining the pulp vitality. Conservative caries removal techniques have been proposed, including indirect pulp capping, partial removal, and stepwise excavation. Turner & Hode (2004) considered that laser therapy can be commenced for pulp capping & pulp amputation of deciduous teeth. Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 90

91. Lasers induce calcification, resulting in the formation of ideal reparative dentin to a greater extent than that achieved by traditional methods. The fine area of hemostasis created by laser includes a thin layer of necrosis, below which there is an area where the injury can be reversed, i.e., a place for migration of inflammatory cells and the fibroblasts that contribute to the formation of the dentinal bridge. 91

92. PBM ( photobiomodulation ) effect could also be applied effectively in direct pulp capping and lead to successful reduction of inflammation, stimulation of cells, promotion of cell proliferation, and controlled promotion of partial calcification of the vital pulp. 92

93. 1. Indirect Pulp Capping All the laser wavelengths allow for deep decontamination in the outer and inner dentin layers, but it is the full cavity preparation performed with the Er -family lasers that offers several advantages. Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 In this procedure, the deepest layer of carious dentine is coated with biocompatible and bioactive materials. It is believed that the bacteria present in this residual thin layer of caries are well sealed and inactivated by medicaments and restorative materials, providing the pulp with an opportunity to resume its reparative activity 93

94. Advantages of Er laser : Reduced heating in pulp during cavity prep. Reduced intra-chamber pressure during the vaporization of deep carious dentin layers that leads to a reduced possibility of accidental misplacement of infected chips in the pulp chamber. Er lasers are more selective for carious tissue ; thus allowing complete caries vaporization while preventing possible unwanted pulp exposure. Detoxify the surface up to 300-500 μ m , so ensuring a deeper decontamination in dentin. 94

95. PROCEDURE : Complete caries removal : ≤ 150 mJ 15 to 20 Hz Short pulse duration (100-300 μ s) With air/water spray on. Final decontamination – should be done carefully to avoid damage to pulp. 70-80 mJ 10 Hz 100 µ pulse duration In focused mode, with water spray. 95

96. The seal of the deep dentin area close to pulp, also called as “Dentin Melting” , allows the prevention of post-op sensitivity. It is executed in a defocused mode at : 25 mJ 10 Hz Short pulse duration (100-300µs) With air on to cool the operative field for 5 to 10 s. (No water or low air-water spray) 96

97. Application of a bioactive liner (Ca(OH)2, MTA, or Biodentine) and an immediate composite filling – allows for a hermetic seal of cavity. 97

98. Lasers induce calcification, resulting in the formation of ideal reparative dentin to a greater extent than that achieved by traditional methods. The fine area of hemostasis created by laser includes a thin layer of necrosis, below which there is an area where the injury can be reversed, i.e., a place for migration of inflammatory cells and the fibroblasts that contribute to the formation of the dentinal bridge. 98

99. 2. Direct Pulp Capping If the diagnosis has been correct, the exposure is minimal, the surrounding area is clean and decontaminated, and the erbium laser makes this procedure more predictable. Pulp capping is recommended when the exposure is very small - ≤ 1.0 mm and the patients are young. The success rate of pulp capping (Direct/Indirect) ranges from 44 to 97% . Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 99

100. DIRECT PULP CAPPING BY LASER -CO2 Laser irradiation is performed at 1 or 2W after irrigating with 3% sodium hypoclorite and 3% hydrogen peroxide for about 5 minutes. 75 mJ 10 Hz Apply a Ca(OH)2 medication and a hermetic temporary sealing (with GIC or Biodentine) in order to stimulate the formation of reparative dentin to complete the 1 st session . Pulsed Nd : YAG, argon, semiconductor diode, and Er:YAG can also be used 100

101. A herm e tic pulp-dentin interface seal ensures the maintenance of the decontamination and at the same time, stimulates the formation of the tertiary dentin which enhances the healing of the treated tooth. According to the studies, a hermetic seal of the pulp exposure & an immediate permanent filling after the pulp capping allow for a superior success rate. 101

102. 2 nd SESSION : after 4-6 months Liner material is completely removed. Underlying dentine must be checked with a probe and an excavator. A final laser decontamination is performed before the final restoration. 102

103. EJPD 2015- Results - Traditional technique group showed a success of 63% ; Er,Cr:YSGG laser-assisted technique showed a success rate of 80% ; Erbium:YAG lasers laser-assisted technique showed a success rate of 75% 103

104. MDPI photonics 2023 Conclusions- Within a three-year follow-up, it can be concluded that in direct pulp capping, irradiation with a CO2 laser before the conventional application of Ca (OH)2 significantly increases the success rate of DPC. Moreover, the use of the 980 nm diode and Er: YAG lasers showed a lower success rate when compared to the conventional application of Ca (OH)2 alone. 104

105. Matsuo et al. analysed the relationships between the success rates of pulp capping to carious exposed pulp and some clinical findings and found that the age of the patients, type of teeth, responses to thermal stimuli and percussion, and diameter of pulpal exposure had no influence on the success rate, while the degree of bleeding was indicative of the prognosis of this treatment. He found that the success rate of the study was 81.8 % and also estimated the length of time necessary for adequate postoperative follow-up to be 20–24 months. He also mentioned that a good haemostasis increases the success rate of the procedure. 105

106. ADVANTAGES : Decontaminates the exposed area, superficially or more in depth, depending on the wavelength used. Coagulates the pulp, leaving a dry site very suitable for a capping material. Moreover, the irradiated & coagulated pulp presents an amorphous necrotic superficial layer that avoids any direct contact of whichever capping material is used with underlying vital pulp, making the choice for the liner wider. 106

107. 4. Pulpotomy It entails surgical removal of a small portion of vital pulp as a means of preserving the remaining coronal and radicular pulp tissues. It is recommended when the young pulp is already exposed to caries and the roots are not yet fully formed. (Open apices) Melcer et al. (1987) 1 st described laser treatment of exposed pulp tissue using the CO2 laser in dogs to achieve haemostasis and noticed that there was new mineralized dentin formation without cellular modification of pulpal tissues. Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 107

108. Procedure : CO2 LASER : Performed at 1 or 2 W after irrigating with 8% NaOCl and 3% H2O2 for more than 5 minutes. Calcium hydroxide paste must be used to dress the exposed pulp after laser treatment, after which the cavity should be tightly sealed with cement such as polycarboxylate cement. CO2 laser usage is time consuming and pulp tissue may be damaged due to several exposures. 108

109. Nd:YAG Neodymium:YAG (1,064 nm) laser is well absorbed by haemoglobin and scarcely by water so that the interaction with dentin is purely thermal and ineffective for carious removal. Thus, cavity preparation must be performed with mechanical rotative instruments, and the laser can only be used for the final decontamination and coagulation of the exposed pulp. Pulsed Nd : YAG causes damage to the pulp tissue and thereby showed a low success rates so it should be used only for pulp haemostasis, sedation, anti-inflammatory effects, and stimulation of remaining pulpal cells. 109

110. Due to its deep tissue interaction, it is advisable to reduce the emitted energy during cavity decontamination (75 > 50 mJ , 10 Hz, 100 μs ) and coagulation of tissue which may otherwise cause necrosis of the pulp (100 mJ , 10 Hz, 300 μs ). 110

111. Diode Laser The diode lasers (from 810 nm up to 980 nm) are well absorbed by haemoglobin and are well suited for cavity decontamination and coagulation of the exposed pulp. After preparing the cavity with mechanical instruments, the laser should be used in defocused mode to decontaminate the exposed surface using a 400-μm non-activated fiber at 1 W, pulsed emission. 111

112. 4. Partial Pulpotomy In the case of PP, the recommended extent for removal of the inflamed pulp varies from 2 to 4 mm Conventionally, the exposed pulp tissue is removed using a sterile round shape diamond bur to a depth of 2–4 mm. Bleeding is controlled with sodium hypochlorite or ferric sulphate, and in case of protracted or heavy bleeding, the diagnosis of irreversible pulpitis is made, and the therapy is pulpectomy (RCT) Laser energy is able to vaporize the pulp tissue, decontaminating and coagulating the residual pulp; laser leads to favourable results using different wavelengths (Nd:YAG, Er,Cr:YSGG or Er:YAG, and CO2). Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 112

113. PROCEDURE : The Er family laser is used to vaporize the coronal pulp; the laser is set on appropriate parameters : 120–150 mJ 12–15 Hz 140–300 μs W ith air–water spray on This procedure is repeated two or three times for 10–15 s, with intervals of 30 s until vaporization of the pulp tissue is obtained at the desired depth. 113

114. Bleeding control is performed using lower energy. Once the bleeding is controlled, the pulp is dressed with a layer of non-hardening calcium hydroxide, followed by a second layer of self-hardening calcium hydroxide ( Dycal ), or MTA ( ProRoot ), or Biodentine , a placement of permanent restoration guarantee the hermetic seal of the cavity. 114

115. 5. Apexogenesis Laser can be beneficial in this field for two reasons: 1. It contributes to the maintenance of pulp vitality through the coagulation and decontamination of the exposure site through the laser- assisted pulpotomy . 2. It can, possibly, biostimulate the maturation process . Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 115

116. Fekrazad et al. studied the biostimulating effects of a diode laser (810 nm, 0.3 W, 4 J/cm 2 , for 9 s) to accelerate the rate of dentinogenesis in apexogenesis of immature permanent dog teeth, using MTA as capping agent and reporting positive results. Mathur et al 2014. in a case study reported the successful use of a diode laser for vital pulpotomy in traumatically exposed pulp of an 8-year-old boy, to ensure continued root development and apexogenesis . 116

117. Figure 1: Pre-operative (a) 8-year-old male; tooth # 12; history of trauma (b) tooth # 12 on radiograph showing immature apex 117

118. Figure 4: (a) 1 month post-operative radiograph (b) 3 month post-operative radiograph (c) 6 month post-operative radiograph (d) 10 months post-operative radiograph 118

119. Advantages Of Using Lasers For These Procedures : Anaesthesia – not necessary Heat generated in the pulp chamber is not harmful to the pulp tissue. The preparation – selective for carious tissue with high water content; No risk of over-treatment or mechanical exposure. A bloodless field would be easier to achieve due to the ability of the laser to vaporize tissue and coagulate & seal small blood vessels. The treated wound surface would be sterilized . Bio-stimulating effect 119

120. The histologic efects of various laser types on pulp tissue The application of lasers in vital pulp therapy: a review of histological effects a review Farzaneh et al 2023 120

121. Low level laser therapy CLINICAL TECHNIQUE Pulse frequency 15 to 20 Hz. Pulse energy 80 to 120mJ Water Mist spray should be set – ON Contact or Non-contact Handpieces can be used The Energy should delivered at CEJ. Laser in dentistry: An innovative tool in modern dental practice review article 2020 121

122. Mankar N, Burde K, Agrawal P, et al. (October 30, 2023) Application of Low-Level Laser Therapy in Endodontics: A Narrative Review 122

123. LOW LEVEL LASER THERAPY • Acceleration of wound healing • Enhanced remodelling and repair of bone • Restoration of normal neural function following injury • Normalization of abnormal hormonal function • Pain attenuation • Stimulation of endorphin release • Modulation of the immune system. 123

124. Application of Low Level Laser in Endodontic Treatments 1- Laser therapy in decreasing dentin hypersensitivity- Low level laser irradiation of cervix and apex region of sensitive teeth can be an appropriate treatment to eliminate sensitivity. Action is by blocking of the depolarization of sensory C fibers 124

125. 2- Laser therapy in treatment of wounds and periapical lesions- Laser therapy result in better wound healing by the following mechanisms on the 3 phases of primary inflammation, proliferative and remodeling phases. - Increased synthesis of RNA, DNA and proteins - Angiogenesis and neovascularization - Accelerated epithelialization 125

126. 3. Pain reduction- Regarding the significant pain reduction in LLLT group at 4, 8, 12, and 48 hours after endodontic treatment, LLLT seems to be an effective and nonpharmacological approach for the reduction of post-endodontic treatment pain 126

127. 4. Laser therapy in accelerated anesthesia In patients experiencing problems during anesthesia, with irradiation of 2 to 3 J of laser on apex of teeth, blood circulation of the area improves and anesthesia with lidocaine is obtained sooner. 127

128. 128 Int J Paediatr Dent. 2022- Conclusions: It has been determined that the application of topical anesthesia  +  LLLT with an 810-nm diode laser before local infiltration anesthesia reduced injection pain and did not have an effect on anesthesia efficacy and duration in children.

129. 129 BMC Oral Health 2025-The established protocol for LLLT is as follows: GaAlAs infrared laser emitter, wavelength of 808  nm, 100 mW , continuous emission mode, contact point, exposure time per point of 25 s, energy density per point of 90 J/cm2 , energy per point of 2.5 J, single application per session

130. 130 Bonacina et al. Protocol for low-level laser therapy (LLLT) to control post-endodontic treatment pain in patients with apical periodontitis: a randomized controlled trial BMC Oral Health (2025)

131. 131 Dent J.2023- Two protocols for the use of low-power diode lasers were found within the various studies: • 810 nm, 30 mW , and 10 J/cm2 for 9 s per point, with three sessions at 72 h intervals • 685 nm, 25 mW , and 9 Hz for 100 s for three sessions at 72 h intervals

132. 132 Journal of Lasers in Medical Sciences 2018- The combined use of the GaAlAs laser (830 nm wavelength) with fluoridation enhances treatment effectiveness by more than 20% over that of laser treatment only.

133. 133 Kumar and Mehta reported that the combination of Nd: YAG laser and 5% NaF varnish seems to show an impressive efficacy when compared to each treatment alone Goharkhay et al., reported that CO2 laser irradiation through a layer of stannous fluoride causes a highly resistant layer on sensitized dentin. This layer induced by physical and chemical bonding mechanisms, provides a superior defense against external stimuli

134. LASERS IN ANALGESIA Its wavelengths interfere with the sodium pump mechanism, change cell membrane permeability, alter temporarily the endings of sensory neurons, and block depolarization of C and A fibers of the nerves. 134

135. LASER THERAPY TO REDUCE NAUSEA DURING STAGES OF ROOT CANAL THERAPY AND RADIOGRAPHY Nausea is one of the most common problems during dental treatments. Some clinicians use acupuncture to reduce nausea. It is possible to use laser instead of special needles. For this purpose, at least 2J of energy is used in the hand wrist area and P6 Meridian point. Application of the laser to the P6 acupuncture point of the wrist will decrease the gagging and nausea sensations many patients feel during dental treatments, impressions and x-rays. 135 Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023

136. Laser in Access Cavity Preparation Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 136

137. Lasers used : Er,Cr:YSGG (2780 nm) Er:YAG (2940 nm) Because they remove both the hard & soft tissue when in contact. While preparing the access cavity, the energy of the laser light progressively decreases in depth. (From D to P) Enamel 250 mJ > Carious Dentine 200 > 150 mJ Pulp 150 mJ Canal Orifice 120 > 80 mJ Suggested energy settings : 137

138. The use of a short tip is recommended (from 4 to 6 mm), with diameters between 600 and 1000 μm , made of quartz to allow the use of higher energy and power. (Larger diameter – More elevated energy & power during the ablation of E; Larger irradiated surface) Chen et al. demonstrated that bacteria are killed during cavity preparation up to a depth of 300 to 400 μm below the radiated surface. Er lasers are also useful in the removal of the pulp stones & in the search of calcified canals. 138

139. 139 FIGURE 10-5 ● A to C, Er,Cr:YSGG laser tips to create endodontic access openings (A) and to instrument canals in anterior teeth (B), and posterior teeth (C) .

140. Why Er Lasers Are Preferred For Access Cavity Preparation ? 1. Er lasers have high affinity for water present in carious dentin & pulp. Therefore, they help in : Removal of caries Selectively uncover pulp horns with less energy Decrease the risk of false path 2. Due to their selectivity with action, Minimally invasive access Consistent ablation of the bacterial load occurs. They further reduce the contamination with bacteria, toxins & debris in apical direction. 140

141. SHAPING & CLEANING OF ROOT CANAL Review Article - Role of laser in conservative dentistry and endodontics I P Indian Journal of Conservative and Endodontics 2022 141

142. Various laser systems can be delivered into the root canal system by a thin optical fiber ( Nd:YAG , erbium family, argon, diode) or by a hollow tube (CO2 and Er:YAG ). Thus, the potential bactericidal effect of laser irradiation can be used effectively for additional cleansing of the root canal system following biomechanical instrumentation. 142

143. It also has been documented in numerous studies that CO2, Nd:YAG, argon, Er,Cr:YSGG , and Er:YAG laser irradiation has the ability to remove debris and the smear layer from the root canal walls following biomechanical instrumentation. 143

144. LIMITATIONS THAT MAY BE ASSOCIATED WITH THE INTRACANAL USE OF LASERS: The emission of laser energy from the tip of the optical fiber or the laser guide is directed along the root canal and not necessary laterally to the root canal walls . Thus, it is almost impossible to obtain uniform coverage of the canal surface using a laser Another limitation is the safety of such a procedure because thermal damage to the periapical tissues potentially is possible. Direct emission of laser irradiation from the tip of the optical fiber in the vicinity of the apical foramen of a tooth may result in transmission of the irradiation beyond the foramen. 144

145. This new endodontic side-firing spiral tip ( RCLase ; Lumenis , Opus Dent, Israel) was designed to fit the shape and the volume of root canals prepared by nickel-titanium rotary instrumentation. It emits the Er:YAG laser irradiation laterally to the walls of the root canal through a spiral slit located all along the tip. The tip is sealed at its far end, preventing the transmission of irradiation to and through the apical foramen of the tooth A. Stabholz et al / Dent Clin N Am 48 (2020) 809–832 145

146. 146 G, RCLase Side Firing Spiral Tip. H, Prototype of RCLase Side Firing Spiral Tip is shown in root canal of extracted maxillary canine

147. 147 Scanning electron microscope photographs of a nonlased wall of root canal at its middle part demonstrates unclean surfaces of root canal walls, with smear layer and debris. Dentinal tubules cannot be seen. (Magnification × 300.)

148. Laser Techniques used In Endodontics 1. Conventional Direct Irradiation 2. Photo-activated Disinfection (PAD) 3. Laser-activated Irrigation (LAI) 4. Photon-induced Photoacoustic Streaming (PIPS) Current Applications and Future Directions of Lasers in Endodontics: A Narrative Review Bioengineering 2023 148

149. 1. Traditional Laser Endodontics (Direct Laser Irradiation) Olivi in 2013 , called this technique “Conventional Laser Endodontics” , in order to distinguish it from the more recent PAD & LAI. 149

150. Mechanism : Requires the canals to be prepared in the traditional way; the apical prep. is performed with ISO #30/40, depending on the laser fibre diameter used. The irradiation is performed at the end of the traditional endodontic treatment, as a final procedure to reduce bacteria in the endodontic system before obturation . Laser fibre/tip is inserted into the canal up to the radicular apex (conventionally 1 mm from the anatomical apex). The optical fibre/tip : 200-300 µm Flexible Resistant to negotiate anatomical curvatures of the canal with minimum risk of breakage 150

151. The activation of the laser starts during the movement of retraction of the fiber /tip, in a determined time (1-2 mm/s). The helical/circular movement of the tip/fibre is required to increase the irradiation angle b/w fibre & dentin surface. (To improve the energy diffusion) This technique is suitable for most of the wavelengths in the visible (445 & 532 nm), near-infrared (from 810 to 1,340 nm) and medium-infrared (2780 & 2940 nm) zones of electromagnetic spectrum. (Depending on the presence & concentration of the specific chromophores on canal surface & inside dentinal tubules) 151

152. 152

153. Lasers In Root Canal Preparation 153

154. The length of the root canal, obtained through the X-ray, is transferred to the fibre-optical wave guide to ensure that the flexible 200 μm fibre reaches the apex. The laser is activated only after the fibre reaches the apex and the fibre is guided in an apical to coronal direction with rotary movements and in contact with the root canal wall. When the laser fibre is unable to be inserted into the canals, reamers and files are to be used, followed by lasers. 154

155. Nd:YAG Removes the smear layer. Superficial inorganic melting – occludes the dentinal tubules (Gutknecht et al. 1991) SEM – presence of areas of fusion & recrystallization, esp. in the apical 3 rd . (Possible seal to bacterial recolonization – Moogi & Nageshwar , 2010 ) 155

156. 2. Er lasers They are used because of their Recognized ablative capacity of hard tissue FDA approval for BMP An SEM observation after the use of Er:YAG laser showed that the dentine surface is equally clean from the coronal to the apical portion without any pulp remnants & clean open dentinal tubules. ( Kesler et al., 2002) Shoji et al. 2000 used an Er:YAG laser system with a conical tip with 80% lateral emission and 20% emission at the tip to enlarge and clean the canals using 10 to 40 mJ energy at 10Hz, obtaining cleaner dentinal surfaces compared with traditional rotary techniques. 156

157. Several studies using Er,Cr:YSGG laser : End-firing tips (Diameter – 200 & 320 µ) → Clean, irregular dentin surfaces, better than the conventional manual instrumentation. Less smear layer They concluded that when used at an angle < 10° - Well perfomed > 15° - Risk of ledging , perforations & over-instrumentation (Ali et al. 2005, Matsuoka et al. 2005, Jahan et al. 2006) One study compared 3 different techniques of instrumentation : conventional manual, rotary & laser They concluded that the cleaning was equivalent for all in the coronal & middle 3 rd ; but more efficient in the apical 3 rd with the conventional methods. (Roper et al. 2010) 157

158. CONCLUSION : Canal surface after laser irradiation – well cleaned without smear layer. Because of ablation Surface is irregular Ledging present Signs of superficial thermal damage Risk of root perforation or apical transportation Thus, lasers are only suitable when the canals are wide & straight, without any advantage over the conventional techniques. 158

159. Near-infrared Lasers Areas of recrystallization of dentin surface where smear layer is fused occluding the dentinal tubules. Smear layer – only partially removed. Carbonization seen. Cracks might be present. Mid-infrared lasers Well-cleaned, but irregular canal walls Decreased thermal damage Vaporize smear layer - Absent Intertubular > Peritubular Protrusion of the dentinal tubules with a cuff-like appearance Open dentinal tubules, increasing the dentin permeability Morphological Changes On Dentin Surface 159

160. Lasers In Removal Of Smear Layer 160

161. Sweeping of Root canal and irrigation are done in Straight, slightly curved and wide canals with lasers. Along with lasers, 5.25% Sodium hypochlorite or 17% EDTA must be used along laser irradiation. Several studies using diode or Nd:YAG lasers after/together with different irrigating solutions ( NaOCl , EDTAC, Chlorhexidine , Distilled water) were done. It was concluded that the morphological pattern was better or similar to that produced by just the irrigation alone. ( Sautos et al. 2005, Gurbuz et al. 2008, Faria et al. 2008, Marchesan et al. 2008, Alfredo et al. 2009, Olivi et al. 2013) 161

162. An in-vitro study, where Er,Cr:YSGG laser, 5.25% NaOCl & RC-Prep was used. SEM results showed that NaOCl alone – Insufficient removal of SL NaOCl & RC-Prep – Moderate presence of SL; Clear areas of exposed collagen Laser & NaOCl – Major SL removal; Some areas of thermal damage with carbonization & melting present. ( Altusander et al. 2019) 162

163. Takeda et al. (1998) compared the smear layer removal efficacy of three lasers: argon, Nd:YAG, and Er:YAG versus a control group irrigated with 17 % EDTA , after conventional instrumentation , in vitro. Statistical analysis showed significant differences between the control and the laser groups. Er:YAG laser irradiation (1 W, 100 mJ at 10 Hz) resulted in absence of smear layer and the presence of open dentinal tubules in the middle and apical one-third. The Nd:YAG laser (2 W, 200 mJ at 20 Hz) showed vaporization of the smear layer but also areas of fusion and recrystallization in the middle or apical one third. The argon laser (1 W, 50 mJ at 5 Hz) showed the presence of pulp remnants in the middle one-third. 163

164. Root Canal Decontamination 164

165. REACTION OF BACTERIA TO LASER PRODUCES KNOCK-ON EFFECT 165

166. 2 possible mechanisms : Laser light is absorbed by the bacteria. (black pigments present – protoporphyrin IX) ↓ osmotic alterations in the bacterial cell ↓ direct damage to the cell wall ↓ cellular death Effects Of Laser Lights On Bacteria 166

167. Laser light is strongly absorbed by the dentine substrate to which the bacteria adheres. The resultant heating of the dentine substrate causes local rise in the temperature. ↓ Death of attached bacterial cells 167

168. A meta-analysis done by Sadik et al. in 2013 concluded that a significant reduction in the count of E. faecalis was seen after the irradiation with Nd:YAG, Er,Cr:YSGG and KTP lasers at 1 & 1.5 W. A complete eradication of E. faecalis was seen only when the canals were irrigated with MTAD and irradiated with a Diode laser. (810 nm, 2 W, 5 times for 5 s) ( Mehrvarzfar et al. 2011) 168

169. Moritz et al., 2000 reported that the E. coli & E. faecalis eradication was seen (at 1.5 W) Er:YAG – 99.64% Nd:YAG – 99.16% Ho:YAG – 99.05% In 2012 , he also reported that the Er lasers does not have bactericidal effect in depth. It only reaches up to 300 µ into the dentinal walls. 169

170. Lasers can activate irrigants in different ways : PAD LAI, PIPS Lasers used : Diode Nd:YAG Er CO2 170

171. Photo-Activated Disinfection (PAD) SYNONYMS : Antimicrobial Photo-dynamic therapy ( aPDT ) Light-activated therapy (LAT) Light-activated disinfection (LAD) Photodynamic antimicrobial chemotherapy (PACT) Photodynamic inactivation (PDI) Lethal photosensitization 171

172. “A treatment modality that uses 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. In the field of dentistry, PAD was introduced as a new disinfection method providing a powerful antibacterial action and thus improved results in a wide range of applications. PAD has been applied to treat periodontal and endodontic infections as well as other oral pathology. 172

173. MECHANISM OF ACTION : The laser light source of PAD – No direct effect on the target tissue; But photo-activates a specific compound that release toxic elements to the target. Fundamental Elements Photosensitizer A light source Tissue oxygen Toluidine blue Methylene blue Chlorins Porphyrins & derivatives Phthalocyanines Xanthenes Monoterpene Indocyanine Riboflavin Pheophorbide -a polylysine Photosensitizers 173

174. STEP-1 Introduction of the photosensitizer into infected tissue. STEP-2 Light illumination (irradiation of the photosensitized tissue) Absorption of the light causes activation of the PS, which excites the drug from its ground-state to excited singlet-state, in the presence of oxygen. This forms free radical ions & singlet oxygen ( ¹O2 ), which has further cytotoxic effects on the cells. 174

175. Spectrum Wavelength Penetration Depth Visible 635 – 675 nm 3- 3.5 mm Near-Infrared 800 – 1,000 nm 4 -5 mm Penetration depth of light – Important The wavelength used for the laser should fall into the range of “therapeutic window” (635-1,000 nm) 175

176. PAD – uses low-power light ( mW ) – No risk of thermal damage to the surrounding tissues. The in-vitro studies have given promising results when this technique was used as an adjunct. Shresha & Kishen reported that the tissue inhibitors present within the RC affect the anti-bacterial activity of PDT at varying degrees, requiring further research in this criteria. 176

177. LIMITATIONS : PS are not evenly distributed across the root canal. It might escape some of the areas of infection. Its penetration into the dentinal tubules has not been investigated. It stains the tooth. Oxygen conc. in the target tissue – PAD is not effective in anaerobic environment (1° RC infections) 177

178. Activation Of The Irrigants 178

179. Laser-Activated Irrigation (LAI) 179

180. DIFFERENT WAVELENGTHS : Er lasers have specific affinity for water. Most widely used for this purpose. Visible & near-infrared lasers have less affinity for water. 180

181. Important factors to be considered for laser activation of the irrigants are : The laser-target interaction The settings Laser energy Pulse repetition rate & duration Fluence The geometry of fibre/tip end Design of the tip & tip-end Tip diameter Position of the fibre/tip in the canal The dimensions of the apical preparation 181

182. 1. Effect Of Laser-tissue Interaction On Irrigants 182

183. Mechanism: 183

184. 184

185. Tip Design It is responsible for : The shape of the bubble formed Direction of the emission of energy Conventional tips Flat-end firing tips Oval bubble, long & almost elliptical shape Frontal emission Conical tips Round bubble, which has 3D emission No apical damage or extrusion Newer tip designs Conical Tapered Tapered & stripped (PIPS) 185

186. Tip Position Goal : Emit energy away from the apex to avoid apical extrusion Efficient cleaning & shaping of RC Studies agree that it is not necessary to place the tip at/near the apex ; but instead suggest to position it at 5 mm distance from the anatomical apex to avoid the extrusion. 186

187. CONCLUSION : At present, Er family lasers are best studied for LAI. Further studies, however, are required to assess the performance of tip design and the influence of the diameter of the tip. Also, due to the lack of the uniformity of the parameters of laser used in different studies, confusion still remains in LAI on how far the tip should be place from the apex for most efficient cleaning of RC, taking into account the safety of the procedure. Also, more research is required for the effectiveness of LAI for disinfection of the RC. Studies have demonstrated that there were no significantly statistical difference b/w PUI & LAI. 187

188. PIPS (Photon-induced Photoacoustic Streaming) 188

189. 1 st – Enrico DiVito in 2006 (acronym) An advanced LAI procedure – the photons of lights are emitted at very low energy levels & short pulse duration (µs) Uses a cutting-edge Er:YAG laser technique At high power peak Extremely low energy levels 189

190. The laser tip is placed stationary in the coronal aspect of the access preparation only. Specific minimum ablative laser settings : low energy (20 mJ ) (Open apex cases – 5, 10, 15 mJ ) 15 Hz Very short pulse duration – 50 µs Allows lateral dispersion Avoid possibility of thermal damage Allows for effective 3D streaming 190

191. The radial firing fibre tip with tapered, stripped side wall 600 µm in Diameter 9 mm long tip Bubbles – spherical 191

192. How Is It Different From LAI Specific & unique tip design Uses sub-ablative or minimally ablative mode of energy (below the threshold of the dentin) Delivered in short pulse duration (produces very high peak power) Easy positioning of the tip Advocates minimal RC & apical preparation (Based on “minimally invasive” or “biomimetic” concept) 192

193. Mechanism The bactericidal effect of the PIPS system results in 3 events- 3D streaming of fluids – improved deeper penetration in dentinal tubules Increases reactive rate of NaOCl Shock-wave like phenomenon (induces cell lysis , mechanical breakup of the bacterial biofiolm ) 193

194. Its mechanism of action is by creating a strong photoacoustic shockwave that streams irrigants three dimensionally throughout the root canal system. This creates an expansion and successive shock waves leading to the formation of a very powerful streaming of the fluid located inside the root canal, with no rising of temperature. 194

195. PIPS Protocol The PIPS tip is placed in the pulp chamber only (not in the root canal) and held stationary throughout the activation process. During the time of laser( Er : YAG laser) activation, the dental assistant applies a continuous flow of the solution from the dental irrigating syringe. The laser activation period for PIPS is in 30 s cycles. The current protocol is six 30 s cycle of laser activation. 195

196. 196

197. 197

198. 198 Fig. 24_SEM images of radicular dentine covered with bacterial biofilm of E. faecalis before laser radiation. Figs. 25 & 26_SEM images of radicular dentine covered with bacterial biofilm of E. faecalis after radiation with Er:YAG laser (20 mJ , 15 Hz, PIPS tip) with irrigation (EDTA), showing destruction and detachment of bacterial biofilm and its complete vaporisation from the principal root canal and from lateral tubules. Laser in endodontics Laser in endodontics-Prof Giovanni Olivi

199. obturation 199

200. Due to their thermal effects clinicians have also tried using lasers like the Nd:YAG for thermosoftening gutta-percha; however there isn't much of an advantage seen over the thermoplasticised gutta-percha obturations systems commercially available today. Nd:YAG laser has also been used for sectioning excess gutta percha left after lateral compaction techniques. 200

201. Sousa- Neto , et al demonstrated that application of Er:YAG laser beam (200 mJ , 4 Hz) for 60 seconds enhanced the adhesion of epoxy resin-based sealers in comparison with zinc oxide-eugenol-based sealers. A study by Sousa-Neto, et al – Improved adhesion of an epoxy based sealer to human dentin that had been irradiated with the Er:YAG or Nd:YAG laser. Anic and Matsumoto reported that the temperature elevation on the outer root surface was 14.4° C using the Nd:YAG and 12.9° C using the argon laser. Such a temperature increase may be detrimental to the tissues of the periodontal ligament and attachment apparatus of the teeth 201

202. 202 Gekelman et al.reported significant improvement in the quality of the apical sealing of root canals using the Nd:YAG laser (100 mJ /pulse, 1 W, 10 Hz).

203. 203 ●  Laser-assisted root canal filling. A, Preoperative radiographs of upper-right maxillary incisor showing internal resorption. B, A root perforation is visible on the measurement radiograph. C, Tooth filled with calcium hydroxide

204. 204 . D, Laser tip in canal RCLase used for disinfection The canal was treated with the erbium laser energy and sealed with gutta-percha. E, Lateral maxillary incisor after completion of root canal filling using hot gutta-percha technique. F, Two-year follow-up radiograph reveals complete healing of periapical lesion. Sinus tract disappeared, and patient is free of symptoms.

205. The photo-polymerization of camphoroquinone –activated resins for obturation is possible using an Ar laser emitting @ 477 & 488 nm. (Potts & Petrou 1990, 1991) The results indicate that an Ar laser coupled to an optical fibre could become a useful modality in endo therapy. Similar studies have been performed using the obturation material AH-26 (Zaman et al. 2012 ) and composite resin (Anic et al.2010) . An SEM examination revealed that laterally compacted resin fillings showed fewer voids than those obtained by vertical compaction. 205

206. Shock wave-enhanced emission photoacoustic streaming (SWEEPS) C reated in order to increase the debriding efficiency of the PIPS method The working mechanism of SWEEPS is similar to extracorporeal shock wave lithotripsy. As the cavitation bubble begins to collapse, a second pulse is transmitted through the liquid, thereby causing a second cavitation bubble. Then, the second cavitation bubble accelerates the collapse of the first one, thus forming a violent collapse Finally emitting a shock wave which removes debris attached to the dentinal wall. 206

207. Protocol For Retreatment Cases Used at standard settings with the water feature on for the dislodgement of the canal material. Used along with alcohol and hydrogen peroxide to dissolve the material without the air-water spray on. GP solvents (Chloroform, Ensodolv ) should be used separately from the PIPS system to avoid any possibility of a inflammable incident. 207

208. Anjo et al. (2004) reported that the time required for the removal of any root-canal filling materials using laser ablation was significantly shorter than required using conventional methods. It appeared that following laser irradiation, some orifices of dentinal tubules were blocked with melted dentin. They concluded that Nd:YAG laser irradiation is an effective technique for the removal of the RC filling material. 208

209. The rationale for using laser irradiation in non-surgical retreatment may be ascribed to the need to remove foreign material from the RC system that may otherwise be difficult to remove by conventional methods. he Nd:yttrium alminum perovskite (YAP) laser emitting at 1340 nm (200 mJ & a frequency of 10 Hz) was suggested as an effective device for root canal preparation in endodontic retreatment. 209

210. 210 BMC Oral Health 2021- Compared to PUI and CSI, activation of 2.5% NaOCl and 17% EDTA with PIPS ( using Er:YAG laser with a 300-µm endodontic fber tip 20  mJ , 15 Hz, 50-µs pulse, average power, 0.3 W greatly improved the removal of the residual iRoot SP and gutta-percha following NiTi mechanical retreatment.

211. 211 Endodontology 2019- Conclusion: The present study revealed that the diode laser with solvents (Chloroform and Endosolv E) were significantly more effective than only diode laser group in removing gutta‑percha during retreatment of the root canal system. Out of these, Group 2 (diode laser along with chloroform as solvent) was more effective than other groups.

212. Protocol For Calcified Canals Used with 17% EDTA Coronal calcification – higher energy used (30 – 40 mJ ) PIPS is also helpful in locating and helping negotiate calcified canals A pulsed dye laser emitted at 504nm was used for the removal of a calcified attached denticle . SEM evaluation showed a sharp surface at the base of the pulp stone after the removal. (Rocco et al) 212

213. Protocol For Removal Of Fractured Instruments Bypass – alternating cycles of NaOCl & EDTA + PIPS Dislodgement – photoacoustic shock waves Several cycles of distilled water agitation or Directly with the handpiece water spray on 213

214. The Er:YAG laser represents cutting-edge technology for laser-activated irrigation (LAI) and 3-D disinfection. Specifically, this laser can eliminate pulp tissue remnants; bacterial biofilms, when present; and, fortuitously, many intracanal obstructions, such as a broken instrument. 214

215. Unlike other forms of LAI, PIPS utilizes a uniquely tapered and stripped tip that is confined to the pulp chamber only. PIPS generates shockwaves at subablative levels and actively pumps fluid three-dimensionally into both minimally or fully prepared canals and their related root canal systems. 215

216. The exposed portion of the PIPS tip is placed stationary and centered within a fluid-filled pulp chamber containing 17% EDTA and activated. The resultant burst of energy produces enormous shear-wall forces similar to that of a pressure washer used to clean paint from stone, brick, or concrete. Strategically, this energized reagent can be used to safely break up dentinal debris packed between a broken file segment and the dentinal walls and uncover the broken file segment. 216

217. The removal method is encouraged by using 3 to 4 irrigation cycles at 30 seconds each, alternating between NaOCl and EDTA. In this manner, the canal can often times be recovered, giving the clinician the opportunity to three-dimensionally disinfect and fill this root canal system 217

218. 218

219. Apicectomy 219

220. Er:YAG laser-osteotomy and root end ressection Nd:YAG –sealing dentinal tubules LLT Ga -Al-As diode laser-improved healing J Clin Surg Med 2001 220

221. Miserendino used CO2 laser to irradiate the apex during apicoectomy . Other lasers used are ErYAg , NdYag .. 221

222. The main aim is to convert the apical dentin and cementum structure into a uniformly glazed area, preventing ingress Hemostasis and sterilization of the contaminated root apex also have a significant input 222

223. In vitro studies using the Nd:YAG laser have shown a reduction in the penetration of dye or bacteria through resected roots. It was suggested that the reduced permeability in the lased specimens probably was the result of structural changes in the dentin following laser application A. Stabholz et al / Dent Clin N Am 48 (2004) 809–832 223

224. ADVANTAGES better visibility; accurate apical resection; no contact; removal of lesion in a shorter time by vaporization; hemostasis ; no vibration or discomfort and minimal pain; and less bacterial risk of trauma to adjacent tissues 224

225. Other Uses In Endodontics 225

226. Vertical Root Fracture – Diagnosis & Treatment There are very few studies examining the use of laser in diagnosing VRF cases. Although, Kimura et al. (2009) used DIAGNOdent for VRF detection in-vivo, this technique appears to be impractical for clinical use. 226

227. VRF can be treated using a surgical approach on the # side, which involves cleaning of the # line & filling with composite resin/bioactive materials. Thereafter, lasers can be used to accelerate soft tissue repair , and this has been performed previously using low power laser therapy. ( Nogueira et al. 2012) 227

228. CO2 & Nd:YAG lasers have been used for the attempted treatment of root fractures. Regardless of the reapproximation technique, laser type, energy & other parameters used, fusion of the fractured root halves was not achieved. (Arakawa et al. 200 6) 228

229. 229

230. The CO2 laser has been shown to be highly consistent in its ability to create this “glaze” layer on the dentin surface with minimal to-no associated surface cracking. This surface glazing effect initially was postulated to decrease dentin permeability. The clinical rationale for this reported case was that if the fracture could be covered with the glaze layer resulting from CO2 laser irradiation at the proper exposure parameters, then the leakage through the fracture interface could be substantially reduced and the chance of resolution of the periodontal infection would be increased. 230

231. Sterilization Of Dental Instruments Ar , CO2, Nd:YAG lasers have been used successfully to sterilize dental instruments. Results indicated all 3 lasers are capable of sterilizing dental instruments. However, Ar laser was able to do so consistently at the lowest energy level of 1 W for 2 min. (Adrian & Gross 1979, Hooks et al. 1980, Powell & whisenant 1991) 231

232. Indications & Contraindications Of Lasers In Endodontics 232

233. Teeth with purulent pulpitis or pulp necrosis Teeth with gangrenous changes in the pulps of crown & root Teeth with periapical lesions ( periapical gap from 1 mm, up to granulomas with a diameter of 5 mm & more) Teeth with periapical abscess Teeth with lateral canals that lead to periodontal involvement Absorption of the apex caused by inflammation or trauma Teeth that have been treated for at least 3 months without success Removal of temporary cavity sealing materials & root canal sealing materials, and fractured instruments In fine & strongly curved canals Laser-supported treatment should be favoured when treating pts that show one or several of the following symptoms : 233

234. Laser in Caries Detection 234

235. Quantitative light/laser‑induced fluorescence QLF is based on the principle of fluorescence. It enhances early detection of carious lesions, particularly progression or regression of white spots of smooth surface lesions. It provides a fluorescent image of a tooth surface within yellow‑green spectrum of visible light that quantifies mineral loss and size of the lesion It is a suitable method for quantitative assessment of early enamel lesions in visually inaccessible areas. Most important Digital imaging fiber‑optic transillumination. parameters produced by QLF are lesion area, depth, and volume. Mohanraj, et al.: Diagnostic Methods for Early Detection of Dental Caries – A Review 235

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238. At times, a red fluorescence appears that indicates leaking around restorations and sealants. It is emitted by porphyrins metabolized by bacteria in dental biofilm, calculus, or an infective carious lesion and usually indicates a high caries activity 238

239. DIAGNOdent ‑ laser autofluorescence DIAGNOdent was first introduced in 1998 to aid the diagnosis of occlusal caries in adjunct to visual and radiographic examination. It is a variant of QLF system and was introduced based on research by Hibst and Gal. DIAGNOdent system is a part of exciting new generation of dental equipment. It uses infrared laser fluorescence of 655 nm for the detection of occlusal and smooth surface caries 239

240. Mechanism of action DIAGNOdent technology uses a simple laser diode. At specific wavelength that the device operates, healthy tooth structure exhibits little or no fluorescence, resulting in very low scale readings on the display. Carious tooth structure exhibits fluorescence proportionate to the degree of caries, resulting in elevated scale readings on the display As the laser pulses into grooves, fissures, and cracks, it reflects fluorescent light with particular wavelength. This is because light is absorbed by the organic and inorganic components of the tooth which induce infrared fluorescence. This fluorescence is collected at the top of handpiece and transmitted back to the DIAGNOdent unit. Light is measured by receptors, converted into an acoustic signal, and evaluated electronically to reveal values between 0 and 99 240

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242. DIAGNOdent pen DIAGNOdent pen is an advancement made in the DIAGNOdent technology. DIAGNOdent pen 2190 is the perfect tool to detect fissure and smooth surface caries accurately 242

243. Laser in Caries Removal 243

244. The Er:YAG , Er:YSGG and Er,Cr:YSGG lasers are used for effective caries removal and cavity preparation without significant thermal effects, collateral damage to tooth structure, or patient discomfort. Normal dental enamel contains sufficient water (approximately 12 per cent by volume) that a water mist spray coupled to an Er-based laser system can achieve effective ablation at temperatures well below the melting and vapourization temperatures of enamel. 244

245. A characteristic operating feature of Er-based laser systems is a popping sound when the laser is operating on dental hard tissues. Both the pitch and resonance of this sound relate to the propagation of an acoustic shock wave within the tooth, and vary according to the presence or absence of caries. This feature assists the user in determining that caries removal is complete. 245

246. 246 FIGURE 11-1 ● A, Dental caries presents a risk to natural tooth structure and vitality of dental pulp B, Using Er:YAG laser, selective removal of dental caries can be achieved with maximal preservation of healthy, mineralized tooth tissue. C, Completed restoration

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251. 251 Ideal laser ablation of tooth tissue is achieved by approximating the handpiece tip just out of contact with the tooth surface (1mm clearance) during laser emission the tip should be moved back and forth over the target to develop cavitation. Once entry into the tooth cavity has been achieved, it is important to allow adequate access for the water spray, both to provide cooling and to prevent accumulation of ablation debris. It is recommended that the laser tip be pumped in and out of the laser cavity to ensure adequate water spray

252. 252 Laser-assisted cavity preparation draws on a “minimalistic” approach: the advantage of removal of only diseased tissue Both erbium lasers will leave a cut surface without a smear layer, and using a proprietary bonded dentin protector, calcium hydroxide, or glass ionomer lining is recommended on open tubules exposed by the ablation process.

253. 253 The reported ablation threshold for human enamel is 12 to 20 J/cm2, and for dentin, 8 to 14 J/cm2, using Er:YAG and Er,Cr:YSGG laser wavelengths. For an average laser delivery spot size, using a free-running pulsed emission mode, this may be 150 to 250 mJ /pulse. With the development of better coaxial coolant and shorter pulses, fast and efficient cavity preparation can be achieved with power levels of 400 to 700 mJ per 10 to 20 pps (average power, 4-8 W), which with adequate water cooling does not cause pulpal damage .

254. 254 A, Carious cavity in upper-left central incisor. B, Outline form was determined using Er:YAG laser (2940 nm) with water spray (450 mJ /pulse, 10 Hz) C, Completed restoration.

255. B leaching using Lasers Effectiveness of Laser-Assisted Teeth Bleaching: A Systematic Review Jan Kiryk et al applied sciences 2024 255

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257. Laser-assisted bleaching can enhance the whitening effect for both natural teeth and dental restorative materials. A diode laser, with wavelengths ranging from 808 nm to 980 nm,is the most frequently utilized laser Interestingly, it was observed that when using 35% hydrogen peroxide, the best whitening effects were achieved with a laser power of 1.5 W, regardless of whether the wavelength was 810 nm, 940 nm, or 980 nm 257

258. The Er:YAG laser has a more beneficial effect on endodontically treated teeth, thanks to the possibility of using a lower HP concentration compared to the walking bleaching method. • When assisting whitening with a diode laser, it is more beneficial to use a shorter wavelength. • Laser-activated bleaching reduces post-treatment hypersensitivity. 258