Irrigation in endodontics

A powerpoint presentation on irrigation in endodontics, icluding all the current techniques , drawbacks and the recent advances

1. IRRIGATION TECHNIQUES in endodontics Presented by Mettina 1

2. contents Introduction History Ideal requirements Goals of irrigation Classification Some commonly used Irrigants Irrigation techniques Newer irrigation solutions. Newer irrigation techniques. Sequence of irrigation Conclusion 2

3. INTRODUCTION… 3

4. Unprepared root canal surface areas: causes, clinical implications, and therapeutic strategies Abstract: Chemomechanical preparation is intended to clean, disinfect, and shape the root canal. This step is of utmost importance during treatment of infected teeth with apical periodontitis , because treatment outcome depends on how effectively the clinician eliminates bacteria, their products, and necrotic tissue that would serve as substrate for bacterial regrowth . Nonetheless, curvatures and complex internal anatomical variations of the root canal system can pose a high degree of difficulty in reaching these goals. In infected teeth, bacteria may persist not only in difficult-to-reach areas such as isthmuses, ramifications, dentinal tubules, and recesses from C-shaped or oval/flattened canals, but also in areas of the main canal wall that remain untouched by instruments. If bacteria withstand chemomechanical procedures, there is an augmented risk for post-treatment apical periodontitis . This article discloses the reasons why some areas remain unprepared by instruments and discusses strategies to circumvent this issue and enhance infection control during endodontic treatment/retreatment of teeth with apical periodontitis . 4

5. 5 Superimposed micro-computed tomographic images taken before (green) and after (red) the use of rotary NiTi instruments revealing areas that remained unprepared (green). 

6. Enterococcus faecalis : its role in root canal treatment failure and current concepts in retreatment. Stuart CH 1 ,  Schwartz SA ,  Beeson TJ ,  Owatz CB . Author information Abstract Enterococcus faecalis is a microorganism commonly detected in asymptomatic, persistent endodontic infections. Its prevalence in such infections ranges from 24% to 77%. This finding can be explained by various survival and virulence factors possessed by E. faecalis , including its ability to compete with other microorganisms, invade dentinal tubules, and resist nutritional deprivation. Use of good aseptic technique, increased apical preparation sizes, and inclusion of 2% chlorhexidine in combination with sodium hypochlorite are currently the most effective methods to combat E. faecalis within the root canal systems of teeth. In the changing face of dental care, continued research on E. faecalis and its elimination from the dental apparatus may well define the future of the endodontic specialty. 6

7. 7 E faecalis penetrates deep into dentinal tubules, Biomechanical preparation alone cannot eliminate the pathogen.

8. INTRODUCTION The success of endodontic therapy depends on eradication of microbes from root canal system & prevention of reinfection . Irrigation is a key part of successful root canal treatment. Basic functions of Irrigants It reduces friction between the instrument and dentine, Improves the cutting effectiveness of the files. Dissolves tissue, Cools the file and tooth,. Washing effect and an antimicrobial/antibiofilm effect. Irrigation is also the only way to impact those areas of the root canal wall not touched by mechanical instrumentation 8

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10. History Potassium hypochlorite- France , Bertholiet -1748-1822 Sodium hypochlorite – Labarraque - late 19 th century. Prior to 1940’s water was the most commonly used irrigant used as it was readily available as it provides a lubricating effect during instrumentation. 1940’s – Streptokinase, Papain & other proteolytic enzymes were used. Grossman & Meiman in 1943- NaOCl 3% Hydrogen peroxide, 5.25% Sodium hypochlorite- Effervescent action. 1957- Nygaard Ostby introduced EDTA as an aid for preparation of canals. 1978- Quarternary ammonium solutions- Spangberg In 1979 Phosphoric acid, Citric acid , Lactic acid used 10

11. 3 % Hydrogen peroxide, 5.25% Sodium hypochlorite- Effervescent action. 1957- Nygaard Ostby introduced EDTA as an aid for preparation of canals. 1978- Quarternary ammonium solutions- Spangberg In 1979 Phosphoric acid, Citric acid , Lactic acid used 1980- electrochemically activated water used. 1980- Martin & colleagues , NaOCl & Ultrasonics - synergistic action. 1982- Chlorhexidine was introduced by Delany as an irrigant . Last few decades- Ozone , Photodynamic therapy, Lasers 11

12. IDEAL REQUIREMENTS 12

13. Ideal requirements – grossman 13th 13

14. Goals of irrigation - weine 14

15. Goals of irrigation- ingle 15

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17. CLASSIFICATION By Stock 17

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19. CLASSIFICATION - Kandaswamy et al 19 Chemical agents Tissue diisolving agents eg - NaOCl , ClO2 Antibacterial agents 1) Bactericidal eg : CHX 2) Bacteriostatic eg : MTAD Chelating agents 1) Mild pH- HEBP 2) Strong pH-EDTA Natural agents Antibacterial agents eg : Green tea, Triphala

20. CLASSIFICATION 20 ALKALINE SOLUTIONS Sodium Dioxide Urea Sodium hydroxide Sodium hypochlorite Potassium hydroxide Chloramine T ACIDIC SOLUTIONS Organic acid (Citric acid, Maleic acid, Tannic acid, Phosphoric acid, Lactic acid) Inorganic acids- H2SO4, HCl OXIDISING AGENTS 3% H2SO4 Urea peroxide Glyoxide

21. CLASSIFICATION 21 CHELATING AGENTS EDTA EDTA-C RC prep PROTEOLYTIC ENZYMES Streptokinase Enzymol Streptodomase Purified trypsin Papain OTHERS Chlorhexidine gluconate Glutaraldehyde Oxidative potential water 2% potentiated acid 1% Pentanedial Calcium hydroxide solution Bardac 2

22. SOME COMMONLY USED IRRIGANTS 22

23. CHEMICALLY INACTIVE SOLUTIONS 23

24. NORMAL SALINE Normal saline causes gross debridement & lubrication of root canals. Can be used as an adjunct to chemical irrigation. Flushing action Final rinse to remove chemical irrigants left behind. 24

25. Advantages Biocompatible No adverse reaction Osmotic pressure same as that of blood. Disadvantages No dissolution or dissolving properties Too mild to thoroughly clean the canals Cannot clear microbial flora from inaccessible areas Does not possess antimicrobial activity Does not remove smear layer. 25

26. TISSUE DISSOLVING AGENTS 26

27. SODIUM HYPOCHLORITE 27

28. SODIUM HYPOCHLORITE (0.5-5.25%) Sodium hypochlorite is a clear ,pale, green yellow liquid with strong odour of chlorine. Easily miscible in water Decomposed by light 28 History Introduced in World war I by Dakin Walker in 1936 – suggested its use in RCT Grossman 1941- Used it as an intracanal medicament. Spangberg-1973 – 0.5% NaOCl has good germicidal activity Madden 1977- Compared different concentrations of NaOCl

29. MECHANISM OF ACTION At body temperature- hypochlorite ( OCl -) & hypochlorous acid ( HOCl ). When hypochlorous acid comes in contact with organic tissue, it acts as a solvent & releases chlorine, which combines with protein amino group to form chloramines. The Chloramination reaction (Cl- + NH) forms chloramines that interfere in cell metabolism. Dissolves necrotic tissue due to alkaline pH- 12. Chlorine- antimicrobial causes irreversible oxidation of Sulphydryl group of bacterial enzymes. Buffering with sodium bicarbonate increases efficacy of NaOCl . 29

30. Mode of action – sodium hypochlorite NaOCl + Fatty acids= Soap+ Glycerol NaOCl + Amino acids= Salt+ Water NaOCl + H2O = NaOH + HOCl = Na+ + OH- + H+ + OCl - 30 Saponification reaction Neutralization reaction Chloramination reaction

31. Methods to increase efficacy 31 TIME TEMPERATURE SIDE VENTED NEEDLES ULTRASONIC IRRIGATION

32. FACTORS AFFECTING EFFICACY 32 Volume of the solution Heating the solution (60-70 degrees) Time of contact Storage time Chemical agents- ( EDTA)

33. PRECAUTIONS 33

34. ADVANTAGES/ DISADVANTAGES Advantages Causes tissue dissolution Antibacterial& bleaching action Lubrication of canals Economical Easily available Disadvantages Increased surface tension, less ability to wet dentin. Irritant to tissues Inflammation of gingiva Bleaches clothes Bad odor & taste Vapors irritate eyes Corrosive to instruments 34

35. Antimicrobial property The most effective irrigation regimen is 5.25% at 40 min. Siquiera et al Irrigation with 1.3% & 2.5% NaOCl for the same interval is ineffective in removing E faecalis from the root canals. Retamozo et al NaOCl was moderately effective against bacteria but less effective against endotoxins in root canals. Martinho et al 35

36. Effect of sodium hypochlorite on dentin Degradation of organic dentin. Clear concentration dependent effect of NaOCl on mechanical dentin properties. Sodium hypochlorite penetration into dentinal tubules- Increasing the concentration from 1% to 6%. Zou et al reported that the highest values of penetration 291 & 300 mm were with 6% NaOCl at 37 degree Celsius for 20 minutes. 36

37. COMBINATIONS Combination with Calcium hydroxide, EDTA or chlorhexidine increases efficacy. Pretreatment with Calcium hydroxide increases efficacy of Sodium hypochlorite & Chlorhexidine. Wadachi et al -combination of calcium hydroxide and sodium hypochlorite is better than use of either medicament alone. Sodium hypochlorite + EDTA- better Alternate use of sodium hypochlorite & Chlorhexidine results in greater reduction of microflora.- Kuruvilla et al 37

38. ANTI- BACTERIAL AGENTS 38

39. HYDROGEN PEROXIDE It is a clear odourless liquid. 3% solution- irrigating agent. Mechanism of action Highly unstable- easily decomposed by light & heat. Dissociates into H2O & O The nascent oxygen in contact with tissue enzymes- catalase & peroxidase produces bactericidal effect. Causes oxidation of bacterial sulfhydryl group of enzymes. Bacterial metabolism 39

40. Nascent oxygen- Bubbling effect- mechanical debridement, floats debris to the surface. Uses Effervescent reaction- pulses debris mechanically out of the root canal. Sollvent action of sodium hypochlorite on organic debris Precaution- in combination with sodium hypochlorite, Sodium hypochlorite should be used last. 40

41. UREA PEROXIDE White crystalline powder with slight odor Mechanism of action- Dissociates rapidly into Urea & Hydrogen peroxide, both exert their individual action. 10% solution of urea peroxide in anhydrous glycerol is available as Glyoxide Advantages of adding glycerol Increases stability & shelf life Good lubricant Glyoxide can be used along with EDTA Disadvantage- slow dissociation as compared to hydrogen peroxide, prolonged effervescence. 41

42. CHLORHEXIDINE Chlorhexidine developed- late 1940’s Most potent of tested bisbiguanides . Most stable- Chlorhexidine gluconate. Potent antiseptic, chemical plaque control. Optimal antimicrobial action- Ph 5.5-7.0. Should be used in 2% concentration. 42

43. structure Chlorhexidine is a synthetic cationic bisguanide that consists of two symmetric 4-chlorophenyl rings & two Biguanide groups connected by central hexam -ethylene chains. 43

44. CHLORHEXIDINE 44

45. Mechanism of action CHX is a positively charged hydrophobic & lipophilic molecule that interacts with phospholipids & lipopolysaccharides on the cell membrane of the bacteria & enters the cell. The positive charge of the molecule interacts with the negatively charged phosphate groups on the microbial cell walls. The osmotic equilibrium of the cell is altered. In turn permeability of the cell wall increases allowing the CHX molecule to penetrate into the bacteria. Damage to this membrane is followed by leakage of intracellular constituents ( ATP & Nucleic acids) 45

46. Advantages 2% used as root irrigant in canals. 0.2% controls plaque activity. More effective on Gram positive bacteria than gram negative bacteria. Disadvantages Unable to dissolve necrotic tissue Less effective on gram negative than on gram positive bacteria. 46

47. Chlorhexidine & dentin bonding Carillho et al – Chlorhexidine has broad spectrum MMP inhibitory effect, thus can significantly improve resin- dentin bond stability. 47

48. Irrigant solutions with added detergent 48 6% NaOCl & Chlor-XTRA were superior against E faecalis compared to 2% CHX & CHX Plus.

49. SODIUM HYPOCHLORITE + CHX Additive antimicrobial effect 2.5% NaOCl + 0.2% CHX 49 NaOCl is an oxidising agent Oxidises the gluconate part of CHX to gluconic acid Chloro group gets added into the guanide component. CHLORHEXIDINE CHLORIDE

50. 50 NaOCl + CHX Immediate formation of orange –brown precipitate ( para- chloro aniline) NaoCl / CHX precipitate tends to occlude dentinal tubules. Bui et al Precipitate could be prevented by using absolute alcohol or minimized by using saline or distilled water as intermediate flushes.

51. CHELATING AGENTS 51 Chelating agent is defined as a chemical which combines with a metal to form a chelate. EDTA – Nygaard Ostby for cleaning & shaping of canals.

52. EDTA Serper et al- For optimal cleaning & shaping EDTA should be used at a lower concentration & neutral pH. Functions- Lubrication Emulsification Holding debris in solution Smear layer removal. Dentin dissolving properties . 52

53. MECHANISM OF ACTION Inhibits growth of bacteria, ultimately destroys them by starvation. 53

54. FORMS OF EDTA R EDTA- combined with cetrimide, better cleaning of canals. EDTA –T – Combined with sodium lauryl sulphate, decreases surface tension. EDTA-C - Contains cetavelon , a quarternary ammonium compound, helps in disinfection. A chelating agent can be added in liquid or paste form. The use of paste type preparation first advocated by Stewart. EDTA+ Urea peroxidase + Water soluble Carbowax ( polyethylene glycol ) as vehicle 54

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56. CITRIC ACID Another commonly used solution for removal of Smear layer is citric acid. It should never be used in combination with NaOCl because it reduces the available Chlorine in solution making it ineffective against bacteria 10% citric acid has been shown to remove the smear layer more effectively from apical root end cavities than ultrasonics . JOE 1994 56

57. HEBP- Etidronate Hydroxyethylidene Bisphosphonate also known as Etidronate is a weak chelating agent. It is the only chelating agent that can be safely used with NaOCl without affecting its proteolytic or antimicrobial properties. HEBP is a weak decalcifying agent & hence cannot be used as a mere final rinse. 57 NaOCl + HEBP Better tissue dissolution capaci

58. Effect of ethylene diamine tetra-acetic acid, MTAD & HEBP as a final rinse on microhardness of root dentin. - Journal of conservative dentistry Aim: This study evaluated the effect of 17% EDTA, MTAD & 18% HEBP solutions on the microhardness of human root canal dentin using Vicker’s microhardness test Results : The microhardness of root dentin following MTAD as a final rinse was significantly less when compared to that of EDTA. This difference could be attributed to the increased depth of demineralization of MTAD (8-12 microns), in relation to EDTA (2-4 microns). HEBP treated root dentin showed the highest microhardness. 58

59. mtad MTAD is a mixture of 3% doxycycline hyclate , 4.25% citric acid & 0.5% polysorbate ( Tween ) 80 detergent. MTAD was introduced in 2000 as a final rinse for disinfection of root canal system. Torabinejad et al showed that MTAD safely removes smear layer & is effective against E faecalis. MTAD helps in- Disinfecting dentin Removing smear layer Open dentinal tubules & allow the antimicrobial agents to penetrate the entire root canal system. 59

60. composition Tetracycline: it is a bacteriostatic broad spectrum antibiotic. It has low pH & acts a calcium chelator Removes smear layer Property of substantivity Promotes healing Citric acid : Bactericidal in nature & removes smear layer. Detergent ( Tween 80) : Decreases surface tension. 60

61. Mode of action Tetracycline is a bacteriostatic antibiotic which exerts its effect through the inhibition of protein synthesis. In the absence of bacterial cell lysis, antigenic by products i.e. endotoxin are not released. Doxycycline, citric acid & Tween 80- synergistic effect on bacterial cell wall.. 61 Cytotoxicity of MTAD- Zhang et al MTAD appeared to be less cytotoxic than eugenol, 3% H2O2, , CaOH paste, 5.25% NaOCl & EDTA It is more cytotoxic than 2.63%, 1.31% & 0.66% NaOCl solutions.

62. ADVANTAGES Effective solution for removal of smear layer. It kills the most significant bacterial strains- E faecalis which is resistant to many agents. Biocompatible Has minimal effects on the properties of teeth. MTAD has similar solubilizing effects in pulp & dentin to those of EDTA. The high binding affinity of Doxycycline present in MTAD for dentin shows prolonged antibacterial effect.. 62

63. Q MIX Q Mix contains EDTA, CHX & a detergent & comes as a ready to use clear solution. CHX & EDTA do not cause a white precipitate & the solution is clear. Low surface tension Qmix - removed smear layer equally well as EDTA . Stojicic et al Antibacterial efficacy & effect on biofilms 6% NaOCl & Q Mix were the most effective disinfecting solutions against the young biofilm, wheras against 3 week old biofilm , 6% NaOCl was most effective. Wang et al 63

64. Irrigation techniques 64

65. Method of irrigation Solution should be introduced slowly & passively into the canal. Needle should never be wedged into the canal & it should allow adequate back flow. Blunted needle of 25 gauge or 27 gauge are preferred. In case of small canals, solution should be deposited in the pulp chamber ( File will carry the solution) Canal – size & shape , crucial. For effective cleaning of apical area, canals must be enlarged to size 30 or larger. Irrigants should not be injected forcibly Needle should be in close proximity to the material to be removed. 65

66. Method of irrigation In case of large canals, the tip of the needle should be introduced until resistance is felt, the needle should then be withdrawn 2-3 mm & the canal irrigated passively. A blunt bend of 30 degree can be given in the center of the needle to clean effectively. Volume of irrigation solution is more important than concentration or type of irrigant . 66

67. Needle designs Stropko irrigator 67 Combination of delivery & recovery of irrigant is present in one probe. Needle delivers the solution, aspirator held in the sheath retrieves the irrigant .

68. 27 gauge needle with notched tip 68 Notched tip allows backflow of solution & does not create pressure in the perapical area.

69. Needle with bevel 69 Needle with bevel if it gets lodged in the canal there is a risk of forcing irrigant past the apex.

70. Monojet endodontic needle 70 This needle is considered efficient as the long , blunt needle can be inserted to the full length of the canal.

71. ProRinse probes 71 This probe is highly effective in all gauges, 27 gauge notch tip needle is more effective as it can clean the periapical area. It has a blunt tip with a lumen 2mm from the tip, fluid from the lumen creates turbulence in all directions.

72. microbrushes 72 In these bristles are attached to braided wires or flexible plastic cores. These brushes can be used as rotary or ultrasonic end brushes. Have a standardized taper. Used in conjunction with Sodium hypochlorite or EDTA to produce clean canals.

73. precautions Avoid wedging the needle. Avoid forcing the solution into the canal. Avoid placing the needle beyond or close to the periapical area. Larger gauge needles should not be used. Metallic autoclavable syringes should be avoided as they are prone to breakage. 73

74. Ultrasonic irrigation Ultrasonic irrigation has been shown to be more effective than conventional irrigation techniques in removing Bacteria & cleaning the canal. Use of ultrasonics causes continuous flow of irrigant in the canal, prevents accumulation of debris in the canal. 74

75. Mechanism of action When a small file is placed in the canal & ultrasonic activation is given, the ultrasonic energy passes through the irrigating solution & exerts acoustic streaming effect. The mechanical energy warms the irrigant solution & dislodges debris from the canal. 75 Advantages Disadvantages It cleans the root canal walls better than conventional methods Removes smear layer efficiently Dislodges debris better due to acoustic steaming effect. Ultrasonic preparation- unpredictable. It can lead to excessive cutting of canal walls & may damage the finished preparation.

76. PASSIVE ULTRASONIC IRRIGATION 76

77. SONIC IRRIGATION Combines battery driven vibrations( 9000 cpm ) with manually operated irrigation of root canal. 77

78. endoactivator 78 Consists of a portable handpiece & three types of disposable polymer tips. 10000 cycles per minute. Stamos et al reported that the more powerful ultrasonic systems removed more dentin debris than the less powerful sonic irrigation systems.

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80. ultrasonic versus sonic activation of the final irrigant in root canals instrumented with rotary/reciprocating files: an  in-vitro  scanning electron microscopy analysis Aim: To compare the smear layer and debris removal in root canals instrumented with two different kinematic motions after ultrasonic and sonic irrigation activation. Materials and Methods: Eighty freshly extracted teeth were selected for the study and randomly divided the samples into two groups ( n  = 40) for instrumentation with either rotary ProTaper NEXT (PTN) or reciprocating WaveOne (WO) file systems. These ( n  = 40) were further divided into two groups ( n  = 20) where the final irrigant was activated using either Ultrasonics (Passive Ultrasonic Irrigation; PUI) or Sonics ( EndoActivator ; EA). Group 1: PTN + EA; Group 2: PTN + PUI; Group 3: WO + EA; and Group 4: WO + PUI. During instrumentation, a total of 4 ml of 5.25% NaOCl was used for irrigation. The final irrigation protocol included NaOCl and Smear Clear Solution. The samples were processed by scanning electron microscopic examination for debris and smear layer scoring, and statistical analysis was done. Results: The mean debris and smear layer score was less in the group instrumented by PTN with sonic activation of the irrigant . Conclusion: A combination of PTN instrumentation with sonic irrigation activation by EA is more effective in debris and smear layer removal in the groups tested. 80

81. Newer irrigating solutions 81

82. Electrochemically activated solution New irrigant solution produced from tap water & low concentration salt solution 82 Tap water or low concentration salt solution Anolyte solution Catholyte solution Super oxidised water or oxidative potential water Preferred solution – anolyte/ catholyte Alkaline or neutral pH Electrochemical treatment

83. Ozonated water irrigation Ozonated water is shown to be a powerful antimicrobial agent against bacteria , fungi, protozoa & viruses. Advantages Potency Ease of handling Lack of mutagenicity Rapid microbial effects 83

84. Antimicrobial efficacy of 2.5% sodium hypochlorite, 2% chlorhexidine, and ozonated water as irrigants in mesiobuccal root canals with severe curvature of mandibular molars. Sergio et al Europ ean journal of dentistry March 2018 Objective: The aim of this study is to evaluate the antimicrobial efficacy of 2.5% sodium hypochlorite, 2% chlorhexidine, and ozonated water on biofilms of  Enterococcus faecalis ,  Streptococcus mutans , and  Candida albicans  in mesiobuccal root canals with severe curvature of mandibular molars. Materials and Methods: This was an experimental  ex vivo  study in microbiologic laboratory. Sixty mesiobuccal root canals with severe curvature of mandibular molars were contaminated with standard strains of  E. faecalis ,  S. mutans , and  C. albicans . The specimens were randomly divided into four groups ( n  = 15) according to irrigating solution: SH: 2.5% sodium hypochlorite; CH: 2% chlorhexidine; O 3 : ozonated water; and control: double-distilled water. The mesiobuccal root canals of all groups were instrumented with the WaveOne Gold Primary reciprocating system. Three cycles of instrumentation with three short in-and-out brushing motions were performed: (1) in the coronal third, (2) in the middle third, and (3) in the apical third of the canal. A ProGlider file was used before the first cycle. Results: All groups showed significant biofilm reduction after irrigation ( P  < 0.01). After instrumentation, sodium hypochlorite (98.07%), chlorhexidine (98.31%), and ozonated water (98.02%) produced a significantly reduction in bacterial counts compared with double-distilled water (control, 72.98%) ( P  < 0.01). Conclusion: All irrigants tested in this study showed similar antimicrobial activity. Thus, ozonated water may be an option for microbial reduction in the root canal system. 84

85. Ruddle’s solution Experimental irrigating solution which was introduced in an attempt to visualize the microanatomy of the canal system. Composition : Seventy percent EDTA Five percent NaOCl Hypaque - aqueous solution of iodide salts- Ditrizoate & sodium iodine . 85

86. Mechanism of action Solvent action of sodium hypochlorite, improved penetration due to EDTA & radiopacity because of Hypaque helps to visualize the microanatomy of the canal system. The solvent action of NaOCl clears the contents of root canal system & enables the hypaque component to flow into every nook & corner of the canal such as fracture, missed canals & defective restorations. Ruddle’s solution is helpful for improving diagnostic accuracy, treatment planning, management of procedural accidents. 86

87. Newer irrigation techniques 87

88. Pressure alternation devices 88

89. Mechanism of action 89 Apical vapor lock in apical 1/3 rd - Major challenge. The endovac system has the ability to create apical negative pressure, which has the ability to suction, thereby drawing & delivering the irrigant passively to the apical 1/3rd

90. Photoactivated disinfection Photoactivated disinfection is a breakthrough in the fight against pathogenic bacteria. It is a fast , effective & minimally invasive disinfection system- kills more than 99% of the pathogens. Mechanism of Photoactivated Disinfection Low powered laser light is transmitted through the disposable Fiberoptic tip to activate the PAD antibacterial solution. Within 1-3 minutes 99% of the microbes are eliminated. 90

91. mechanism Photosensitization is a treatment that involves the interaction of two non-toxic factors, such as a photo-active compound ( tolonium chloride ) and a directly applied visible light (LED illumination at 635nm).  They form metachromatic complexes with lipopolysaccharides that can be photo-activated to cause oxygen ion release. The oxygen ions are specifically toxic to a vital structural component of the target cells. The interactions between the phenothiazine dyes , including toluidine chloride and methylene blue , and many bacteria are well documented. PAD compounds target the cell wall structures and membranes, and do NOT need to enter the cell. Only specific adhesion to the targets is required for the light-activated destruction of the cell hence target cells cannot develop resistance by stopping uptake, metabolic detoxification, or increasing export of the drug. 91

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93. ADVANTAGES It is shown to be the most effective antimicrobial agent, it can effectively kill gram negative, gram positive , aerobic 7 anaerobic bacteria. It overcomes the problem of antibiotic resistance in bacteria. Does not pose any thermal risk. Does not cause any sensitization. Neither the PAD solution nor its products are toxic. 93

94. Aim To investigate the efficacy of photo activated disinfection (PAD) in reducing colony-forming unit (CFU) counts of  Enterococcus faecalis  ( E. faecalis ) in infected dental root canals. The study compared the efficacy of PAD with conventional endodontic treatment (CET) and also a combination of CET along with PAD. Material and Methods 53 maxillary incisors were taken for the study. Teeth were divided into 3 groups, CET (Group I) ( n  = 11), PAD (Group II) ( n  = 21), and a combination of CET and PAD (Group III) which consisted of ( n  = 21) samples, Group II and Group III were further divided into 2 subgroups, Group IIa , IIb and Group IIIa, IIIb . Strains of  E. faecalis  were inoculated in all the root canals. CET group samples were treated by chemo-mechanical preparation (CMP) alone, PAD samples were treated with laser alone at 2 different exposure time (4 min and 2 min). In the combination treatment, samples were treated initially by CET and then by PAD for a time period of 4 min and 2 min. Contents of the root canal were aspirated, diluted and plated in Tryptone Soya Broth (TSB) and plates were incubated for 24 h to observe the bacterial regrowth. Results Showed PAD used along with CMP reduced the bacterial load of  E. faecalis  by 99.5% at 4 min and 98.89% at 2 min. Conclusion PAD may be an adjunctive procedure to kill residual bacteria in the dental root canal systems after standard endodontic root canal preparation. 94 Photoactivated disinfection (PAD) of dental root canal system – An ex-vivo study Dennis mohan et al

95. LASER activated irrigation Due to high energy content & specific charecteristics of LASER light, LASER treatment has been proposed for cleaning & disinfecting the root canal sysyem . Er:YAG , Er:Cr:YSGG , Nd:YAG & Diode lasers can be used in laser activated irrigation. 95

96. Photon induced photoacoustic streaming ( PIPs) 96

97. SEQUENCE OF IRRIGATION 97

98. Sequence of irrigation 98 VITAL TEETH Urea peroxide Sodium hypochlorite NaOCL + K file activation EDTA Collagen anti- aggregation effect

99. NON VITAL TEETH 99 CITRIC ACID CHLORHEXIDINE DISTILLED WATER- end irrigant

100. Sequence of irrigation CONDITION IRRIGANTS Necrotic pulp NaOCl + CHX/ H2O2 Vital pulp exposure NaOCl + H2O2 Calcified sclerotic canal EDTA + NaOCl Infected canal with exudate NaOCl + H2O2 Periapical abscess to establish drainage Hot water / saline ….. NaOCl Open apex/ apical perforation H2O2 + CHX Curved canals Glyoxide + NaOCl Canals left open for drainage H2O2 +CHX Final rinse to remove smear layer EDTA + NaOCl Retreatment cases CHX + NaOCl 100

101. conclusion Irrigation is a crucial step in determining the success of the root canal therapy. The proper choice of irrigant , sequence of irrigation & the right irrigation techniques are crucial to the outcome. Informed case specific decisions on behalf of the practitioner holds the key to minimizing chances of reinfection 100% elimination of root canal pathogens & debris still remains an unconquered domain……… 101

102. BIBLIOGRAPHY Grossman’s endodontic practice -13 th edition Cohen’s pathways of the pulp – 10 th edition Ingle textbook of endodontics Nisha Garg- textbook of endodontics 2 nd edition Journal of endodontics European journal of endodontics pubmed.ncbi.nlm.nih google.co.in 102

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