CALCIUM HYDROXIDE in Dentistry

CALCIUM HYDROXIDE in Dentistry

1. Good morning 1

2. Calcium Hydroxide Guided by Dr.Rambabu . T Professor Presenter Naga Lakshmi II year PG 2

3. CONTENTS Introduction History classification Biochemical actions Mineralization The dentine bridge Destruction of bacteria Dissolution of necrotic material Dental formulations Uses of calcium hydroxide Role of calcium hydroxide today Conclusion 3

4. Calcium hydroxide Slaked lime CaCo 3 →CaO+CO 2 CaO+H 2 0→Ca(OH) 2 Ca 2+ =54.11% 2OH - = 45.89% Torcal De Antequera , Nature reserve of spain LIME STONE 4

5. COURTHOUSE BUILT OF LIME STONE KANSAS, USA USES: BUILDINGS FLOCCULANT DENTISTRY GREEN HOUSE EFFECT PETROLEUM REFINING 5

6. History In Dentistry 1920 -Hermann introduced calcium hydroxide as a pulp capping agent.   1930 - Calcium hydroxide became frequently used in the vital pulp therapies.   1939 -Before the second World War an European immigrant Zander introduced dentists in USA to its use.  1941 -The first literature regarding the successful healing using calcium Hydroxide appeared.   1959 -The use of calcium hydroxide for apical closure was first reported by Granath . 6

7. 1966 - Frank popularized the use of calcium hydroxide for the apical closure.   1975 - Maisto classified the calcium hydroxide paste as an alkaline paste because of its high pH.   1976 - Cvek successfully used calcium hydroxide for induction of hard tissue in the apical portions of the root canal, especially of immature teeth with infected pulp.   1983 - Garcia considered calcium hydroxide as the best medicament to induce hard tissue deposition and promote healing of vital pulpal and periapical tissues.   7

8. Properties Calcium hydroxide is white odorless powder with the formula Ca(OH) 2 . Molecular weight of 74.08. It has low solubility in water which decreases as the temperature rises. Has a high pH(about 12.5 to 12.8). Insoluble in alcohol Chemically classified as a strong alkaline base 8

9. Composition ACID Alkyl salicylate Inert fillers – Titanium oxide Radiopacifer – Barium sulphate Calcium tungstate BASE Calcium hydroxide Zinc oxide Zinc stearate Ethylene toulene 9

10. CALCIUM HYDROXIDE RADIOPAQUE CALCIUM HYDROXIDE THICK PASTE PROVIPASTE TEMPCAL PULPDENT CALASEPT HYPOCAL SETTABLE Ca(OH)2 DYCAL LIFE PROCAL NUCAP HYDREX LIGHT ACTIVATED CALCIUM HYDROXIDE ORGANIC LINER AQUEOUS LINER PLAIN MEDICAL GRADE POWDER ROOTCANAL SEALERS SEALAPEX CALCIBIOTIC UDMA OR Bis GMA METHYL CELLULOSE / NON-METHYL CELLULOSE WATER LIGNOCAINE SALINE RINGER’S PLASMA GLYCERIN OR OIL BARIUM SULPHATE OR IODINE COMPOUNDS ETHYL ALCOHOL OR METHYL ETHYLKETONE SALICYLATES NO ADDITIVE RESIN OR ZOE DISTILLED WATER C U S T O M M A D E C O M M E R C I A L 10

11. CLASSIFICATION Setting Setting Non-setting. Vehicle Aqueous Viscous Oily. 11

12. Dental formulation of calcium hydroxide. SETTING-used for the lining or sub-lining of cavities, or as root canal sealers. NON-SETTING- dressing root canals. Setting materials - Therapeutic effect- pH Levels of unbound calcium and hydroxyl ions 12

13. Setting mechanisms of calcium-hydroxide containing materials. There are two basic setting mechanisms. The two-paste system, which is based on the reaction between calcium and zinc ions and a salicylate chelating agent, and is accelerated by the presence of water (Lim & McCabe 1982). 13

14. The single-paste system, which utilizes the polymerization of a dimethacrylate by means of light. A potential disadvantage of the dimethacrylate systems, when used as a base beneath composite restorations, is their adherence to the composite material and subsequent withdrawal from the base of the cavity during polymerization ( Papadakou 1989). 14

15. Non-setting calcium hydroxide materials Material Vehicle Analar CaOH water Pulpdent Methyl cellulose Hypo-cal Methyl cellulose Reogan Methyl cellulose 15

16. Aqueous Water Saline Dental anaesthetics with or without vasoconstrictors Ringer’s solution Aqueous suspension of Methylcellulose or Carboxymethyl cellulose Anionic detergent solution. Eg : Tempcanal , Calyxyl , Pulpdent . 16

17. CLINICAL IMPORTANCE: Ca 2+ and OH - are rapidly released. High degree of solubility when the paste remains in direct contact with the tissue and the tissue fluids causing it to be rapidly solubilized and resorbed by the macrophages. The root canal must be redressed several times until the desired effect is achieved there by increasing the number of appointments. 17

18. VISCOUS: Glycerin Polyethylene glycol Propylene glycol. Eg : Calen , Calen +CMCPs 18

19. OILY Olive oil Silicone oil Camphor(the essential oil of camphorated parachlorophenol ) Metacresylacetate Some fatty acids such as oleic linoleic isostearic acids. Eg : Endoapex . 19

20. MECHANISM OF ANTIMICROBIAL ACTIVITY : pH Hydroxyl ion DAMAGE TO THE BACTERIAL CYTOPLASMIC MEMBRANE : Hydroxyl ion lipid peroxidation phospholipid hydrogen ion unsaturated fatty acids free lipidic radical + oxygen Autocatalytic chain lipidic peroxide radical Complete destruction ( Cotran et al 1999 ) 20

21. PROTEIN DENATURATION : ( Voet 1995) ionic bond ↑ PH Tertiary structure of protein # covalent structure #polypeptide chain variable irregular spatial conformation X biologic activity X cellular metabolism 21

22. Calcium Hydroxide Induced Mineralization Only in direct contact. Calcium hydroxide is an initiator rather than a substrate for repair. Rise in pH as a result of free hydroxyl ions may initiate the process. Local buffer against acidic reactions Alkaline pH also neutralizes the lactic acid secreted by osteoclasts . 22

23. BIOMECHANICAL ACTIONS Initiation of mineralization Initiators Vit D dep protein Phosphoproteins phospholipids Inhibitors Pyrophosphate ions 23

24. Material exerts a mitogenic and osteogenic effect. High pH activates alkaline phosphatase activity. Heithersay suggested that calcium ions may reduce the permeability of new capillaries , so that less intercellular serum is produced thus increasing the concentration of calcium ions at the mineralization site. 24

25. MECHANISM OF REMINERALIZATION Calcium Hydroxide Reduced capillary Neutralizes acid produced by permeability osteoclasts Reduced serum flow Optimum pH for pyrophosphatase activity Reduced levels of inhibitory levels of ca2+ dependent Pyrophosphate pyrophosphatase Uncontrolled mineralization ca OH− 25

26. Dentine bridge A mineralized barrier or 'dentine bridge' is usually produced following the application of calcium hydroxide to a vital pulp ( pulpotomy ). This repair material appears to be the product of odontoblasts and connective tissue cells. The barrier may not always be complete (Holland et al. 1979). 26

27. Dentine bridge formation varies depending on the pH of the material. High pH- Pulpdent Low pH- Dycal . Can be radiographically differentiated. 27

28. Antibacterial effect of setting calcium hydroxide materials (Fisher & Shortall 1984) Strong effect - Dycal (original formula) Reocap * Procal Medium effect - Dycal (new formula) Life Renew,Reolit * No effect – WPC, Hydrex , Cal- Mer 28

29. Healing with CH Zone of obliteration (early changes; caustic effect: area of superficial debris)- 1 hour. Zone of coagulation necrosis (Schroder’s layer of ‘firm necrosis,” Stanley’s “mummified zone”). The line of demarcation. Dense zone- connective tissue fibers in 2-3 days, extensive collagen formation- 3-7 days. 15 days- UMC into preodontoblasts and columnar shaped odontoblasts . 29

30. Calcification of bridge : 2 weeks- appearance of predentine . 1 month - coronal layer of irregular osteodentin -like tissue with cellular inclusions, and the pulpal part consists of predentin lined with odontoblasts . 3 months -definitely two layered, consisting coronally of dentin like tissue with irregular tubuli and cellular inclusions; the tissue nearest the vital pulp exhibits predentin , densely packed collagen fibrils, and tubules with cellular extensions (Tomes’ fibers ) indicative of a higher level of differentiation. 30

31. Dissolution of necrotic material First reported by Hasselgren in 1988 . The coagulated necrotic tissue above the line of demarcation degenerates completely and collapses. When the tooth is reopened and the CH layer is removed, the clinician’s instrument drops into a chamber or a pit (“the coffin”), the bottom of which is the top of the calcified dentinal bridge. Pulpdent and CH and water . 31

32. CALCIUM HYDROXIDE ROOT CANAL SEALER LINER INTRA CANAL MEDICAMENT PREVENTION OF RESORPTION BASE INDIRECT PULP CAPPING DIRECT PULP CAPPING PULPOTOMY APEXIFICATION HORIZONTAL ROOT FRACTURE PERFORATION REPAIR RESORPTION REPAIR 32

33. Liner They are applied in thickness of 25 micrometers Functions of a liner are minimizing marginal leakage, neutralizing acids and occluding (closing) the exposed dentinal tubules for pulp protection. 33

34. Advantages: Rapid initial set - accelerating effect of moisture in the ambient air of the oral cavity and from within the dentinal tubules. Do not interfere with the setting reaction of Bis -GMA resins- composite resin materials. Initial set in thin sections - sufficiently hard to resist the applied condensation pressures that are required for restoration ( even for amalgam alloys- Lim and Mcabe 1982) 34

35. Base Functions Thermal insulation and to supplement mechanical support for the restoration by distributing local stresses from the restoration across the underlying dentinal surface. An additional function is closing the dentinal tubules - preventing the leached chemicals from the restorations irritating the pulp. Thermal diffusivity of calcium hydroxide is low 35

36. Regular formulations × under amalgam composites. cast restorations 36

37. Vital pulp capping Vital pulp capping is the dressing of an exposed pulp with the aim of maintaining pulp vitality . vital pulp tissue -production of secondary dentin -dentin moist - resilience and toughness --- protection Emphasis has shifted from the "doomed organ" concept of an exposed pulp to one of hope and recovery -CH 37

38. A successful pulp cap has a vital pulp and a dentin bridge within 75 to 90 days Non-sterile procedures and bacterial micro-infiltration of the pulp via dentinal tubules -major causes of post-operative inflammation and pulp necrosis . 38

39. Indirect pulp capping Bactericidal property (king et al. 1965, Fisher 1972) which help to control (Fisher 1977) but not entirely eliminate (Watts & Paterson 1987) the few viable organisms that may remain. 39

40. Indirect Pulp Capping                            After gross excavation, the deepest layer of carious dentine covered with Calasept .                            After 6 weeks the cement was removed, Calasept washed away and the excavation of the carious dentin completed without pulp exposure. 40

41. When the effective dentin (remaining dentine) thickness is more than 100 micrometers , healthy reparative reaction is likely to occur in the pulp. ( i.e. forming reparative dentine and calcific barriers to be followed by secondary dentine containing dentinal tubules formed by odontoblasts . When the effective dentin (remaining dentine) thickness is less than 100 micrometers , healthy unreparative reaction is likely to occur in the pulp. the degeneration of the odontoblasts occur, formation of dead tracts, cessation of secondary dentin formation reversible, mild pathological changes in the pulp differentiation of odontoblasts from undifferentiated mesenchymal cells of the pulp and production of reparative dentin. 41

42. Even with a vital pulp, indirect pulp capping with calcium hydroxide is NOT DONE in Class V cavities in gingival aspects of deep axial walls to prevent excess calcification, strangulating the coronal pulp. The rate of reparative dentin formations has been shown to average 1.4 micrometer per day following cavity preparation in dentin in human teeth. The rate of formation decreases markedly after 48 days (Stanley 1966). For indirect pulp capping, non setting calcium hydroxides provide higher availability of calcium and hydroxyl ions. ( Tamburic et al ). 42

43. The two problems - internal resorption and uncontrolled calcification of the remaining pulp. Calcium hydroxide pulpotomy in a deciduous tooth is usually avoided because of the tendency for internal resorption to occur at the junction between the remaining radicular pulp and the calcium hydroxide. The current view in initiation of resorption is the disruption in predentin layer or precementum layer that offers natural resistance against resorption . 43

44. Seltzer and Bender mention the osteogenic potential of calcium hydroxide which is capable of completely obliterating the pulp chamber and root canals. The current view regarding uncontrolled calcifications is that calcium hydroxide application should be restricted to teeth with healthy pulp. If the pulp is degenerating, application of calcium hydroxide can alter the pulpal degeneration into calcific degeneration . 44

45. Apexification Agent: Apexification is a procedure attempted in non-vital tooth with an immature apex. The interim calcium hydroxide root canal filling serves the purpose of stimulation of the calcific barrier in the apical root end against which gutta percha may be condensed. The apexification technique was first reported by Kaiser and Granath and popularized by Frank in 1966. Continued root formation may be expected from the surviving HERS 45

46. The alkaline pastes used are as follows; a) Maisto Cappuro Paste: Calcium hydroxide and iodoform in equal parts with distilled water or a solution of 5 % methyl cellulose. These pastes are rapidly resorbed in the periapical region. The average time for resorption is 1 to 10 days for each square mm of surface of over obturated material as seen in the radiograph. b) Frank’s Paste : Calcium hydroxide and camphorated parachlorphenol . produces a severe inflammatory reaction on initial application. Apexification . Frank also suggested that the camphorated parachlorphenol is an assurance that the paste will remain in the area of apexification for a longer time. 46

47. c) Leonardo’s Paste : Leonardo called this paste as ‘Ca(OH)2 No 9’ It contains Calcium hydroxide, barium sulphate , resin and polyethylene glycol. It is usually used as ; As a dressing between cases of pulpectomy . To protect the vital apical and periapical tissues in the obturation of the root canals. As a temporary obturation in cases of incomplete apexification to induce mineralization and allow formation of new cementum . 47

48. Apexification aims to induce apical closure of the open root apex with a hard-tissue barrier, against which a root filling can be compacted . The frequency of change of CaOH can increase the speed of barrier detection but does not appear to affect the position Change of dressing in 3 months interval. Closure of apex- 6-24 months. Dang N Quintessence Int. 1999 48

49. Medicament for Arresting Resorption : A non perforated internal resorption - may not be possible to remove the hyperplastic pulp tissue from the resorption defect completely. Extirpate the normal pulp near the unvinvolved apical region, thereby cutting the vascularity to the hyperplastic tissue. Pack with calcium hydroxide which has the ability to dissolve the pulp tissue. 49

50. Anderson et al compared the pulp solving ability of 2 % stabilized sodium hypochlorite solution and a commercial calcium hydroxide solution ( Calasept ). Human pulp fragments weighing approximately 0.0065 g were immersed in these solutions at 37 ˚C for 10 days. Sodium hypochlorite was able to dissolve half the volume of pulp tissue within 1 hour and the remaining tissue in 2.5 hours. Calcium hydroxide solution dissolved half the volume of pulp tissue within 2 hours and it took 1 week for the remaining tissues to dissolve. These findings support the use of sodium hypochlorite for canal preparation and calcium hydroxide as a canal dressing, especially in internal resorption cases. 50

51. External resorption - the pulp tissue --- intentionally extirpated Calcium hydroxide - packed into the root. It is postulated that’ the calcium and hydroxyl ions traverse the dentinal tubules and reach the external resorption sites to exert their therapeutic effect.’ Nerwich et al were able to demonstrate pH changes in the outer root dentin over a period of 4 weeks following root canal dressings of calcium hydroxide. Bacterial Lipopolysaccharides (LPS) postulated to play a role in the resorption process intra canal medicament kills bacteria the lysed bacteria can liberate LPS LPS pass onto the periapical region and cause --------action of IL1 , TNF-alpha Safayi and Nichols evaluated the effects of calcium hydroxide on bacterial LPS and found calcium hydroxide was able to hydrolyse the lipid moiety of bacterial LPS. resorption 51

52. Bacterial Lipopolysaccharides (LPS) postulated to play a role in the resorption process Intra canal medicament kills bacteria the lysed bacteria can liberate LPS LPS pass onto the periapical region and cause --------action of IL1 , TNF-alpha Safayi and Nichols evaluated the effects of calcium hydroxide on bacterial LPS and found calcium hydroxide was able to hydrolyse the lipid moiety of bacterial LPS. 52

53. Intra canal medicament Behnen et al. (2001) demonstrated that Ca(OH)2 decreased the numbers of E. faecalis at all depths within dentinal tubules up to 24 h and that less viscous preparations of Ca(OH)2 were more effective in the elimination of E. faecalis from dentinal tubules than viscous preparations. Using an agar diffusion method, Ballal et al . (2007) found that 2% CHX gel was a more effective medicament than Ca(OH)2 paste against E. faecalis . 53

54. Krithikadatta et al . (2007) reported that, as an intracanal medicament, 2% CHX gel alone was more effective against E. faecalis when compared to Ca(OH)2. Lee et al . (2008) concluded that a polymeric CHX-controlled release device (PCRD) was significantly more effective in reducing intradentinal bacteria than Ca(OH)2 54

55. Calcium hydroxide based root canal sealers have been introduced as an alternative to the conventional zinc-oxide eugenol based sealers ( sealapex , CRCS). Mineralized repair - induced. ( Holland and De Souza 1985). When the pattern of release of calcium and hydroxyl ions from different sealers was investigated by Tagger et al in 1988 it was found that Sealapex released ions and disintegrated more rapidly than CRCS. It was also found that although the release of calcium ions from CRCS was negligible, the material continued to alkalize it environment, possibly due to free eugenol combining with calcium ions as they were released. Root canal Sealer 55

56. Ca(OH)2-ZOE . complete biological closure by neoformed cementum . H&E, 100X. Ca(OH)2-Sealapex. There is a biological closure of the main apical foramen. H&E, 100X. 56

57. Biocalex Biocalex (now marketed as Endocalex ) is a variant of calcium hydroxide in paste form. The powder contains Calcium oxide. It is mixed to a slurry with ethylene glycol, ethyl alcohol and distilled water. In 1967, Bernard introduced Biocalex 4 which required a mixing technique to break up inter molecular cohesion of the particles of calcium oxide in order to obtain expansion of about 200%- 280%. 57

58. This formula was modified in 1973 by Bernard, Powder- calcium oxide 66% and zinc oxide 33%. Liquid- consisted of distilled water 20% and ethylene glycol 80%.. 58

59. Bernard’s hypothesis that success is due to expansion of calcium oxide and the accompanying ‘chemical incineration’ plus subsequent obliteration of the whole canal system with calcium carbonate and calcium hydroxide. The hardened material is then destined to remain as a root canal filling. 59

60. 60

61. Calcium Oxide Biocalex - Calcium Oxide, Zinc oxide, glycol/ water liquid. ( ( Endocal ) Volumetric expansion causing penetration of inaccesible canals. Better than calcium hydroxide –control bacteria ( Cavalleri et al 1990) Fill within 1.5 mms from apex –volumetric expansion Not radio-opaque Only available in USA and in Canada 61

62. Apexit: Base: Calcium Hydroxide 31.9% Zinc Oxide 5.5% Calcium Oxide 5.6% Silicon dioxide 8.1% Zinc Stearate 2.3% Hydrogenized Colophony 31.5% Tricalcium Phosphate 4.1% Polydimethylsiloxane 2.5% Activator: Trimethyl hexanediol disalicylate 25.0% Bismuth carbonate basic 18.2% Bismuth oxide 18.2% Silicon Dioxide 15.0% 1,3 Butanediolsalicilate 11.4% Hydrogenized Colophony 5.4% Tricalcium phosphate 5.0% Zinc stearate 1.4% 62

63. CRCS: Calcibiotic root Canal Sealer Powder: Calcium Hydroxide Zinc oxide Bismuth dioxide Barium sulphate Liquid: Eugenol Eucalyptol Sealapex : Base: Calcium Hydroxide 25.0 % Zinc Oxide 6.5% Catalyst: Barium Sulphate 18.6 % Titanium dioxide 5.1% Zinc Stearate 1.0% 63

64. Calcium hydroxide` 30% Iodoform 40.4% Bacteriostatic Increased radiopacity Silicone Oil 22.4% Lubricant , ensures complete coating of canal wall USES: - Intracanal Medicament - Periapical Lesions - Root Resorption - Temporary Root Filling Perforations Pulpotomies in deciduous teeth 64

65. 65

66. American Academy of Pediatric Dentistry 2000; 22:6:517-20 66

67. Acroseal Septodont - root canal sealer Eugenol free. Working time -2 hours Setting time- 24 hours 67

68. J Dent Oral Med 2004, Vol 6 No 01 Treatment of intrabony defects with Alpha-TCP and an oily Calcium Hydroxide suspension. A 14-case-report Alpha- Tricalcium Phosphate + oily Calcium Hydroxide suspension 68

69. CALCIUM HYDROXIDE ROOT CANAL SEALER LINER INTRA CANAL MEDICAMENT PREVENTION OF RESORPTION BASE INDIRECT PULP CAPPING DIRECT PULP CAPPING PULPOTOMY APEXIFICATION HORIZONTAL ROOT FRACTURE PERFORATION REPAIR RESORPTION REPAIR Role of CaOH Today? 69

70. Base or a liner? Sometimes referred to as a base but only should be used a liner. Highly soluble in water and marginal leakage will wash out the material. No long term seal. Endod Dent Traumatol 2000;16:240-250 70

71. Vital pulp therapy Demerits: Tunnel defects- bacterial re-infection. The 1.5-2mm layer of sterile pulp necrotic layer may get infected under leaking restorations thus causing pulpitis and subsequent pulp necrosis if left untreated . Odontol Revy 1971;22: 379-96. International Journal of Dental Sciences and Research, 2014; 2(6B):1-4. 71

72. Few authors have shown that MTA may be a superior material when compared to calcium hydroxide. According to Mente et al., MTA appeared to favour long term pulp vitality after direct pulp capping when compared with calcium hydroxide. Journal of Endodontics 2010;36(5), 806-13 72

73. After performing a histomorphometric analysis of pulp capping of human permanent premolars using calcium hydroxide and MTA, Maria et al. concluded that both the materials were successful but calcium hydroxide was slower than MTA in this regard . Journal of Endodontics , 2008;34(1). 73

74. Apexification And Apexogenesis The time taken for formation of a hard tissue barrier with regard to calcium hydroxide, ranges from 2–3 months and 6–18 months in the case of pulp capping and apexification procedures respectively . Swed Dent J Suppl.2012; 226: 9-84. Calcium hydroxide affects the mechanical properties of dentin when used for a longer period of time rendering the tooth susceptible to fracture 74

75. Perforation management Calcium hydroxide has to be replaced on a regular basis since it is displaced by tissue fluids, exhibits poor marginal integrity, and lacks the required strength. It is hence a temporary solution and the newer materials like MTA have gained popularity as a more permanent solution Endodontics and Dental Traumatology 16, 240-50, 2000 75

76. Root resorption The use of calcium hydroxide in deciduous teeth is discouraged since it may induce chronic pulpal inflammation and internal root resorption . According to Ravi et al. calcium hydroxide-induced resorption in deciduous teeth may be attributed to: (1) inflammatory cytokines, which contribute to transformation of pre- odontoclasts to odontoclasts (2) preexisting progenitor cells with a tendency to transform into odontoclasts , and loss of protective layer of predentin over mineralized dentin. Endod Dent Traumatol . 4(6), 241-52, Dec, 1988. 76

77. Root canal sealers Calcium hydroxide-based sealers exhibit some disadvantages such as milder antibacterial properties, poor cohesive strength, greater solubility, and marginal leakage. J Endod 2009; 1-6. 77

78. Long-term temporary dressing Calcium hydroxide may be regarded as the dressing material of choice because its antimicrobial effect may last for weeks, whilst that of other materials. 78

79. Interappointment dressing slow movement of hydroxyl ions through dentine. Nerwich et al. (1993) - hydroxyl ions diffused in a matter of hours into the inner root dentine but required 1–7 days to reach the outer root dentine and 2–3 weeks to reach peak levels. Hydroxyl ions diffused faster and reached higher levels cervically more than apically. 79

80. A Comparison between the Antimicrobial Effects of Triple Antibiotic Paste and Calcium Hydroxide Against Entrococcus Faecali Triple antibiotic paste with either 2% chlorhexidine or normal saline would be the preferred medicament against E. Faecalis and, among its three components, minocycline has the greatest antibacterial effect. IEJ Iranian Endodontic Journal 2012;7(3):149-155. Alireza et al. 80

81. Precautions Severe chemical burns and irritation. J Can Dent Assoc 2012;78:c57 Loss of eye sight caused by CH paste accidentally splashed into the eye during endodontic treatment: a case report. Immediate action should include: Immediate rinsing, rinsing with 0.9% sodium chloride,administering pt’s own blood into the conjunctival sac,sodium edetate neutralizing. 81

82. Conclusion Survival of the fittest 82

83. References A review of calcium hydroxide.International Endodontic Journal 1990; 23:283-297. Merits and Demerits of Calcium Hydroxide as a Therapeutic Agent: A Review . International Journal of Dental Sciences and Research, 2014; 2(6B):1-4. “MTA versus calcium hydroxide as a pulp capping agent,” Chicago: Quintessence Publishing,2002; 19: 227-245. Fransson H,“On the repair of the dentine barrier,”Swed Dent J Suppl. 2012;226: 9-84. 83

84. “Mechanisms of antimicrobial activity of calcium hydroxide: a critical review,”International Endodontic Journal, 1999;32:361-9. Calcium hydroxide: study based on scientific evidences. J Appl Oral Sci 2003; 11(4): 269-82. Properties and applications of calcium hydroxide in endodontics and dental traumatology . International Endodontic Journal, 2011;44:697–730. 84

85. “FOR A LONG TIME I FELT THAT THE MUMMIFIED LAYER CREATED A SEAL, LIKE A SCAB, WHICH WAS IMMUNOLOGICALLY SIMILAR TO THE VITAL TISSUE BENEATH AND SOMEHOW INITIATED THE HEALING PROCESS. FOR 200 YEARS NATURE WAITED FOR US TO FIND THE EQUIVALENT OF THE SCAB”   HAROLD R STANLEY Thank you 85