1. Root End filling Materials

2. CONTENTS INTRODUCTION
IDEAL REQUIREMENTS OF A ROOT END FILLING MATERIAL
VARIOUS ROOT END FILLING MATERIALS
MISCELLANEOUS MATERIALS
CONCLUSION
REFERENCES

3. INTRODUCTION
The main objective of all endodontic procedures is to obtain a hermetic seal between the periodontium and root canal system, so that no bacteria or bacterial by products can enter or leave from the canal.
Apical resection or apicectomy followed by root end (retrograde) filling is a common treatment when conventional root canal treatment has failed.

4. Throughout the dental history, a wide variety of root end filling materials have been evaluated for biocompatibility, adhesiveness, dimensional stability, solubility, leakage etc in an attempt to identify the ideal material.
A thorough understanding of the available materials is very important for the success of the treatment.

5. IDEAL REQUIREMENTS OF ROOT END FILLING MATERIALS
They should be biocompatible to periapical tissues
Should be insoluble in tissue fluid
They should adhere to the tooth (Adhesion)
Should be bactericidal or bacteriostatic

6. Dimensionally stable
Readily available and easy to handle
Non corrosive, should not stain teeth or periradicular tissue
Radiopaque
Electrochemically inactive
Promote cementogenesis

7. MATERIALS

8. AMALGAM

9. It is the most extensively used retrofilling material from past seven decades.
Farrar (1884) first reported amalgam as a root end filling material
Later Rhein (1897), Faulhaber and Newmann (1912), Happels (1914) and Garvin (1919) supported to the use of amalgam as root end filling materials.

10. Concerns in the use of amalgam as a root end filling can be categorized under the following factors
Type of amalgam (high copper versus conventional, zinc versus non zinc).
Leakage of amalgam root end fillings
Tissue compatibility

11. Preparation and manipulation of the amalgam.
Electric potential – galvanic currents, corrosion and degradation
Pigmentation or argaria of the surrounding tissue.

12. (High Copper Vs Low Copper, Zinc Vs Non Zinc)
Type of Amalgam
(High Copper Vs Low Copper,
Zinc Vs Non Zinc)
In conventional alloy:
2 phases is comparatively weak, corrosion prone
For the short comings of 2 phase the high copper content amalgam were developed

13. Ag3Sn + Cu + Hg = Ag3Sn + Ag2 Hg3 + Cu6Sn5
  
Copper replaces some of the silver in this alloys react to form a copper – tin compound (Cu6 Sn5)  phase which eliminates the weak, corrosion prone 2 phase.
High levels of copper increases the resistance to marginal breakdown, increases dimensional stability and less susceptible to corrosion.

14. Zinc Vs Non-zinc
Effect of moisture on zinc alloys is well established, zinc causes electrolytic disassociation of water into hydrogen and oxygen.
The presence of hydrogen gas causes internal pressure great enough to expand the amalgam from within, which can cause root end expansion, amalgam or root fracture and leakage.

15. Therefore from all the above: high copper zinc free amalgam is preferred as root end filling material.

16. LEAKAGE OF AMALGAM
Multiple techniques have been advocated to determine the apical leakage or marginal adaptation of root end amalgam fillings. These include India Ink, silver nitrate, methylene blue, aniline dye, fluorescent dye, scanning electron microscopy bacterial penetration, radioisotopes etc.

17. The conclusion drawn from these studies was root end amalgam leak minimally adequate at first.
The marginal adaptation as well as sealing improves as amalgam ages ,due to formation of corrosion products.

18. The use of amalgam bond, 4-META bonding agent with amalgam significantly reduces the microleakage of amalgam retrofillings.
4-META monomer contains both hydrophobic and hydrophilic ends, the hydrophobic end attached to amalgam and the hydrophilic end helps bonding to dentin.
This increases dentin sealing and improves resistance but increase in retention form is not significant.

19. TISSUE COMPATIBILITY
Various studies demonstrated that freshly mixed conventional silver amalgam are very cytotoxic due to the unreacted mercury, cytotoxicity decreases rapidly as the material hardens (All unreacted mercury is consumed within 2hours of set).
Amalgam containing zinc have more lasting cytotoxicity compared to non zinc amalgam this is due to the continued release of the ionic species.

20. Various studies identified the cytotoxicity of both low and high copper content alloys. However, the cytotoxicity decreases with ageing possibly due to the surface oxidation and continued amalgamation.

21. MATERIAL PREPARATION AND MANIPULATION
Preparation and manipulation of the amalgam alloy at the time of placement is crucial in determining the strength, marginal adaptation, degree of porosity and surface smoothness.

22. Key points to consider when alloys placed intraorally
Amalgam squeezed of their excess mercury have a decrease in their final strength. The Eames 1:1 ratio technique are preferable.
Amalgams are more closely adapted to the confines of the cavity during mechanical rather than hand condensation, however the use of mechanical condenser may be limited.

29. Optimal structure for the amalgam margins can be obtained by overfilling, burnishing the margin and removal of excess by carving. Burnishing decreases micro porosity, improves marginal adaptation and seal.
Root end amalgams placed at the time of surgery cannot be polished, the unpolished amalgam surfaces have been shown to release greater amounts of mercury and silver, polishing decreases the tendency for corrosion and improves the marginal seal.

30. ELECTRIC POTENTIALS – GALVANIC CURRENTS

31. ELECTRIC POTENTIALS – GALVANIC CURRENTS
Placement of root end amalgam in a tooth which has a metallic post or crown restoration could create a galvanic couple, which has the potential to generate significant amounts of electric currents.

32. Currents in excess of 50µA have been shown to cause tissue necrosis, more over increased production of galvanic currents leads to electro chemical corrosion and releases significant amount of zinc in to the periradicular tissue.
Therefore it is better to avoid or minimize the possibility of this potential problem.

33. TISSUE STAINING – ARGYRIA

34. TISSUE STAINING – ARGYRIA
Staining of hard and soft tissue subsequent to root end amalgam filling could be due to the following :
Amalgam scattered in the surgical site during placement of the root end filling or due to removal of failing root end amalgam.
Fractured or loosened amalgam root end fills
Galvanism and electrochemical corrosion

35. PREVENTION
Control of amalgam particles in the surgical site during amalgam placement
Efficient irrigation and aspiration of the surgical area are essential during removal of previously placed amalgam.
Fracture or loosening of amalgam root end fills can be avoid by proper placement with appropriate bulk in the thickness and by giving mechanical retention in the root end.

36. GUIDELINES FOR AMALGAM USAGE AS A ROOT END FILLING
Although amalgam is not the ideal material, the following concepts should be considered when choosing amalgam as the root end filling material.
Control of moisture in the surgical site is essential
High copper alloys are the materials of choice at present
Varnish or dentin bonding agents must be used prior to alloy placement

37. When moisture cannot be controlled zinc free alloys should be considered
Create a smooth surface of the finished alloy
Prevent the dispersion of alloy particles in the surgical site
Keep the alloy as small as possible in diameter with enough thickness to resists fracture

38. GALLIUM ALLOYS
the toxic effect of mercury led the researchers to think of alternatives.
Gallium alloy was first suggested by Putt Kammer in 1928
Properties
It has the property of wetting many materials including tooth structure.
Alloy of gallium are mixed and condensed as silver amalgam using almost the same instruments

39. Compressive and tensile strength increases with time comparable with silver amalgam.
Expand after mixing therefore provides better marginal seal
Stability and corrosion resistance equal or even greater than silver amalgam.

40. Composition
Alloy Liquid
Silver Gallium
Tin Iridium
Copper
Palladium

41. Reaction
AgSn + Ga  AgGa + Sn
Alloy and liquid are mixed as usual
Structure of gallium resembles that of silver amalgam
Reaction between silver tin particles and liquid gallium involves the formation of silver gallium and pure tin phase.
After mixing alloy tends to stick, therefore more difficult to handle.

42. Disadvantages
Gallium alloy shows surface roughness and marginal discoloration
Since these alloys are sticky manipulation is difficult
Cost is approximately 16 times more than that of silver amalgam.

43. GOLD FOIL
First reports on its use as a root end filling material is attributed to Schuster in 1913 and Lyons in 1920.
Reports in 1960s and 1980s continued to recommend its use because of perfect marginal adaptation, surface smoothness and tissue biocompatibility.
Gold foil was least toxic compared to IRM, composite resin, amalgam, and GIC.

44. Leakage studies in root end preparation have indicated minimal or no leakage.
Although it possesses favorable material properties, the routine use of gold foil as a root end filling material does not appear practical because of the need to establish moisture free environment, the need for careful placement and finishing. However, its use in isolated cases can be justified.

45. SILVER CONES

46. SILVER CONES
Silver cones have been used to obturate the root canals since the early 1930s.
Their ability to seal the root canal three dimensionally has been challenged as the circular, tapered natured of the core provides only a central core material which is surrounded by a sea of root canal sealer.

47. There are several techniques recommended by different people to root end fill with silver cone.
Summers in 1946 presented a reverse canal instrumentation. The cone was inserted into the canal at the resected root end and cutoff, smoothed or burnished to confirm the resected root surface.
This technique was specially recommended when post-core crown was present. The silver cone extend from the resected root end to the apical extent of the post.

48. TRICE recommended a fissure bur to cut the previously placed silver cones, followed by smoothening the surface with the round bur.
GUIDELINES CONCERNING SILVER CONES ROOT END FILLS
Silver cones cannot 3 dimensionally obturate the root canal space, especially in areas coronal to the apex which are likely to be exposed during resection.
Resection of root end containing silver cone will open voids between the cone and dentin wall

49. Resection of silver cone, increase corrosive potential over long periods of time, the corrosive products may be highly cytotoxic.
Silver cones cannot be burnished to perfect apical seal

50. Ideally teeth containing silver cones, requiring surgery should be non surgically retreated with well condensed gutta percha and root canal sealer.
A root end fill is indicated in all cases of root end resection when silver cone is present.

51. GUTTA-PERCHA

52. GUTTA-PERCHA
The placement of gutta-percha as a true root end filling material was considered after the development of thermoplasticized gutta percha
Many studies advocated that orthograde gutta- percha root canal obturation can be used to seal the apex of the root after apicectomy with either cold or hot burnisher
Abdal and Retief observed that heat sealed gutta percha provides better seal as compared to amalgam, IRM and super EBA.

53. Composition Gutta percha - 18.9 – 21.8% Zinc Oxide - 56.1 – 75.3%
Heavy Metal Sulfates – 17.3%
Waxes & Resins – 4%

54. Adaptation to the root canal system & apical seal of gutta percha depends on following
Thoroughness of condensation : many authors recommended coronal condensation of GP into the apical third of the canal and through the foramen, prior to removal of excess material.
Use of solvents : Solvents like eucalyptol or chloroform and rosin to soften the gutta-percha prior to placement into the apical third of the canal or through the resected root end have been advocated to enhance the adaptation of the gutta-percha.

55. Type of Instruments : No studies clearly reported the best instrument for gutta-percha removal at the apex. The instruments like burs, scalpels, spoon excavators, plastic instrument and burnishers have been recommended to remove, contour or adapt the over extended gutta-percha to perfect marginal interface.
Temperature of instrument used :
various dye leakage studies and SEM studies demonstrated that cold burnished gutta-percha yielded superior adaptation compared to heat seal gutta-percha.
Use of root canal sealers : In periradicular surgery the sealer should be non irritating, has hermetic sealing ability, dimensional stability, bactericidal or bacteristatic, insoluble in tissue fluids, and adherence to dentin.

56. Limitations : gutta-percha are porous in nature, it absorbs moisture from surrounding periapical tissue and expands initially which is followed by contraction at a later stage. This may results in poor marginal adaptation.

57. CAVIT

58. CAVIT It is zinc oxide based temporary filling Composition
Zinc oxide, calcium sulfate, zinc sulfate, glycolacetate, polyvinyl acetate polyvinyl chloride acetate, Tri ethanolamine, red pigment.
It is also available in forms without red pigment such as Cavit-G and Cavit W.

59. Cavit is soft when placed in the tooth and subsequently undergoes hygroscopic set after permeation with water, giving a linear expansion. This rationalizes its use as root end filling material.
Various studies shown that cavit exhibit greater leakage than IRM or ZOE
Biocompatibility studies are in conflict, showing it to be both toxic and non toxic. Keeping, these studies in mind the use of cavit as a root end filling materials cannot be advised.

60. ZINC PHOSPHATE CEMENTS

61. ZINC PHOSPHATE CEMENTS
Rhein in 1897 used zinc phosphate cement along with gutta-percha to seal the root canal system prior to root end resection.
Herbert in 1941 recommended zinc phosphate mixed with powdered thymol as a root end filling material following root end resection.

62. Powder Liquid
Zinc oxide Phosphoric acid %
Magnesium oxide - 8.2% Aluminum - 2.5%
Silica dioxide % Zinc - 7.1%
Bismuth trioxide – 0.1% Water – 36.0%
Barium oxide
Barium sulphate
Calcium Oxide
Presently zinc phosphate cement not indicated because of the materials solubility, leakage irritating to tissue and they inhibit healing.

63. POLYCARBOXYLATE CEMENTS

64. POLYCARBOXYLATE CEMENTS
Introduced by Smith in 1968
Consist of powder and liquid, powder contains modified zinc oxide with fillers such as magnesium oxide and stannous fluoride. Liquid contain aqueous solution of polyacrylic acid.
When the cement mixed, the reaction occurs between zinc ion and the carboxy groups of the polyacrylic acid, the free carboxy groups having the capacity to chelate calcium. Therefore adhesion to tooth structure is a significant physical property.
pH of the cement is approximately 1.7 and it become neutralized when the material set, working time of the cement is 3-5mins.

65. LIMITATIONS
Polycarboxylates placed in root canal system or beyond the confines of root apex showed inflammation of periradicular tissue.
Several apical leakage studies reported that polycarboxylates leak at levels significantly greater than amalgam or gutta percha.
Based on poor sealing ability and uncertain periradicular tissue response, the use of polycarboxylate as root end filling material is questionable.

66. Calcium Phosphate Cement (CPC)
Developed by ADA-Paffenbarger Dental Research Center at the United States National
CPC is a mixture of two calcium phosphate compounds,
one acidic and the other basic. Commonly known as hydroxyapatite cement,
it is composed of tetracalcium phosphate and dicalcium phosphate reactants.

67. These compounds, when mixed with water, react isothermally to form a solid implant composed of carbonated hydroxyapatite.
The final set cement consists of nearly all crystalline material, and porosity is in direct ratio to the amount of solvent used.
It is as radio opaque as bone.
When combined by dissolution in moisture, even blood, CPC sets into hydroxyapatite.
It demonstrates excellent biocompatibility, does not cause a sustained inflammatory response or toxic reaction.
Its compressive strength is greater than 60 MPa
shown to maintain its shape and volume over time.

68. DIAKET
Tetsch (1986) first documented the use of diaket as root canal filling material.
It is a polyvinyl resin
For root end filling a slightly thicker consistency of diaket than normal root canal sealer.
Studies showed that diaket provided better apical seal than IRM or super EBA.
Comparative study of diaket and mineral trioxide showed that
Both are biocompatible and promote periradicular tissue regeneration,

69. easy to place than mineral trioxide
sets in a short period, after which it can be polished to the fine rotary instrument.
A study which assessed the radioopacity of various root end filling material documted that diaket has more radiopacity than MTA, GIC, composite cavit, super EBA, IRM and less compared to amalgam and gutta percha.
is insoluble in tissue fluid

70. GLASS IONOMER CEMENT

71. GLASS IONOMER CEMENT
They are found by the reaction of calcium alumino silicate glass particles with aqueous solutions of polyacrylic acid.
It bonds physico chemically to dentin and enamel, and possess anticariogenic activity
The setting reaction is 2 phase. Initially the calcium ions binds to the polyacrylic acid that provides initial adhesion to tooth structure, after than aluminium polycarboxylate are formed. During the initial setting when calcium salts predominate glass ionomers are extremely sensitive to moisture.

72. Biocompatibility study shown evidence of initial cytotoxicity with freshly prepared samples, with decreasing cytotoxicity as setting occurs.
They have good marginal adaptation and adhesion to tooth structure, these properties would enhance the use of glass ionomers as root end filling materials.
The sealing ability of GIC adversely affected when the root end cavities contaminated with moisture at the time of placement.
Newer glass ionomer cements containing glass metal powder (Ketac silver) showed promising results as root end filling material with less leakage and no pathological signs.

73. Chong et al used light cured glass ionomer as retrograde filling
Chong et al used light cured glass ionomer as retrograde filling. It showed less microleakage due to less moisture sensitivity, less curing shrinkage and deeper penetration of polymer into dentin surface.
He also did another study which compared thin (1mm) and thick light cured glass ionomers, greater leakage was found in the thick light cure glass ionomer root end filling. In conclusion he said that light cured glass ionomer was only suitable as a retrograde filling when the thickness was less 1mm.

74. COMPOSITE RESIN

75. COMPOSITE RESIN
Composite resin used in combination with dentin bonding agent showed good apical seal, but a dry field is necessary for dentin bonding agent and composite resin as root end filling because of moisture sensitivity.
Composite resin have received minimal attention as root end filling material because of the cytotoxic effects.

76. Recently Wennerberg reported that composite resin bonded tightly to apicoectomized root with bonding agent showed tissue regeneration including cementogenesis. Moreover use of bonding agent and composite resin permits conservative root end preparation.
All polymerizing resins leave on uncured oxygen inhibiting surface layer that may interface with initial healing and therefore be removed with a cotton swab before wound closure.

77. Retroplast dentin bonding composite system Developed in 1984
2 paste system
Forms a dual cure composite resin when mixed
Working time mins

78. Composition
Paste A: Bis-GMA/TEGDMA 1:1
Benzoyl peroxide
N-di-(2- hydroxyethyl)-p-toluidin
BHT
Paste B: resin yetterbium trifluorideaerosil ferric oxide
GLUMA based dentin bonding agent is used to adhere material to root end surface

79. Limited information available on physical and chemical properties
Material is well tolerated and promoted a good healing response

80. Resin Ionomer suspension (Geristore)
Combination of various properties of composite resins and GIC
require light activation and resin – dentin bonding agents to attach
Paste/paste formulation is hydrophillic Bis – GMA with fluoride release
In vitro study shows superior resistance to leakage than IRM, amalgam,or Super EBA.(JOE 27: 441;2001)
Recommended both as root end filling &use in restoring subgingival surface defects

81. ZINC OXIDE EUGENOL

82. ZINC OXIDE EUGENOL First described by Chisolm (1873)
Nicholls (1962) used ZOE cements as a retrograde filling material the cement tended to be absorbed over time because of its high water solubility.
Composition
Powder Liquid
Zinc oxide – 70% Eugenol – 100%
Rosin – 30%
Zinc acetate traces

83. When zinc oxide cement contact with water or tissue fluids it is hydrolyzed into zinc hydroxide and eugenol.
The eugenol continues to be removed by leaching until all the original zinc eugenolate is converted into zinc hydroxide.
The free eugenol may have several undesirable effects. However the extent of cell death depends primarily on the efficiency of local clearance of eugenol.

84. Eugenol can inhibit prostaglandin synthetase, sensory nerve activity, mitochondrial respiration, eliminates a range of native oral microorganisms and can be an allergen.
Zinc oxide cements were modified in an attempt to resolve these problems

85. IRM (INTER MEDIATE RESTORATIVE MATERIAL)

86. IRM (INTER MEDIATE RESTORATIVE MATERIAL)
It is a zinc oxide eugenol cement reinforced by the addition of 20% polymethyl mechacrylate by weight to the powder.
Developed to over come some of the short coming of zinc oxide eugenol cements.
Composition
Powder Liquid
Zinc Oxide – 80% Eugenol 99%
Polymethylmethacrylate-20% Acetic Acid – 1%

87. With reinforcement the problem of absorbability of ZOE cement is eliminated.
Tissue tolerance and biocompatibility found that IRM elicited a mild to zero inflammatory effect after 80 days, and relatively biocompatible as a retrograde filling material.
To further improve IRM as retrograde filling material, hydroxyl apatite was added.

88. Although, it was shown that the addition of 10% and 20% of hydroxyl apatite produced significantly better seal than amalgam,
However, the addition of hydroxyl apatite to IRM increased its disintegration rate which is a disadvantage, the unmodified IRM does not disintegrate.

89. For root end filling a thick mix of IRM improves placement.
IRM does not adhere well to itself and should be inserted as a single mass and condensed rather than incrementally placed.

90. SUPER EBA (Super Ethoxy benzoic acid)

91. SUPER EBA (Super Ethoxy benzoic acid)
It is a zinc oxide eugenol cement modified with ethoxy benzoic acid to alter the setting time and increase the strength of the mixture.
It has much better physical properties than zinc oxide eugenol
High compressive strength
High tensile strength
Neutral pH
Low solubility

92. Zinc Oxide – 60% Ethoxy Benzoic Acid -62.5%
Adhere to tooth structure even in moist condition and adhere well itself therefore it can be added incrementally.
Composition
Powder Liquid
Zinc Oxide – 60% Ethoxy Benzoic Acid -62.5%
Aluminium oxide – 34% Eugenol – 37.5%
Natural resin-6%
Tissue tolerance shows that the super EBA and eugenol cements produce mild reaction
Super EBA provides better seal than when compared with amalgam, GIC and gutta-percha.

94. Difficult to manipulate, because
Scanning electron microscope and histologic evaluation showed excellent material adaptation to the dentin margins and collagen fibres growing over the material.
Disadvantages
Difficult to manipulate, because
Short setting time,
Material adhere to all surfaces and it may be difficult to place and condense.
Sensitive to temperature and humidity
Only moderately radiopaque

95. MTA (Mineral Trioxide Aggregate)

96. MTA (Mineral Trioxide Aggregate)
Developed at Loma Linda university (1993) for use as root end filling material.
Commercially available as Pro Root MTA.
Composition
Tricalcium Silicate
Tricalcium Aluminate
Tricalcium Oxide
Silicate Oxide
Mineral Oxides in tracers bismuth oxides

97. It is a powder consists of fine hydrophilic powder, that sets in the presence of moisture. Hydration of powder results in colloidal gel.
pH immediately after mixing is 10.2, rising to after 3 hours.
Setting time is 4 hours, compressive strength – 70MPa, comparable that of IRM and super EBA but significantly less than amalgam.

98. Advantages
Least toxic of all the filling material
Excellent biocompatibility – when MTA comes into contact with periradicular tissue regeneration of new cementum over MTA is a unique phenomenon, mechanism of cementum formation is unclear.
It can be by two mechanism, calcification of fibrous connective or activation of cementoblasts.

99. It is hydrophilic
Reasonable radiopaque
Disadvantages
Difficult to manipulate
Long setting time

100. Mixing MTA MTA should be prepared just before it use
Powder should be mixed with sterile water at a ratio of 3:1 to a putty like consistency.
Mixture can be carried with a messing gun or amalgam carrier to the obturation site and condense it with the small plugger.

102. If the area of application is very wet the extra moisture can be removed with a dry piece of gauze
Initially MTA was available as gray powder. Recently white powder introduced by the exclusion of iron compounds and the particles size are smaller compared to gray MTA.

103. White MTA composed primarily of tricalcium silicate and bismuth oxide
White MTA composed primarily of tricalcium silicate and bismuth oxide. Gray MTA composed primarily of tricalcium silicate, dicalcium silicate and bismuth oxide.
Leakage studies showed the white MTA shows more leakage than gray MTA.

104. MISCELLANEOUS MATERIALS
Bone Cement
One new material that may potentially provide the necessary properties for an ideal retrofill material is bone cement.
Composition
Powder Liquid
Polymethylmethacrylate Methylmethacrylate
Barium Sulfate
Cement exhibits low cytotoxicity, excellent biocompatibility, inhibits bacterial growth, tolerates moist environment.

105. TITANIUM Most frequently used material for dental implants
Has excellent corrosion resistant, high mechanical strength, good biocompatibility and can be easily formed into any shape.
Yasumori et al developed titanium inlay as a new root end filling. Result of study showed no clinical or radiographic problems or any of the tooth.
Demerits
Metallic materials should no longer considered because they share many of the problems of amalgam.
An isthmus cannot be filled with titanium inlay. In these areas the cements used will be exposed to periradicular tissues.

106. ALUMINIUM OXIDE PLUS
Has excellent biocompatibility with a tight sealing of the root canal.
Keller et al reported a success rate of 95%
Contra indicated in large oval cross sections

107. CONCLUSION
Root end filling material should provide a hermetic seal, should be non-toxic, non-carcinogenic, biocompatible and dimensionally stable.
Based on studies and clinical performance it is clear that IRM, super – EBA, and MTA are the recommended materials available for root end filling. The sealing ability of MTA is superior to that of IRM and super-EBA. The regeneration of new cementum over MTA is a unique phenomenon that has not been reported with other root end filling materials thus making MTA the retrofilling material of choice.

108. Surgical Endodontics – James L. Gutmann
Colour atlas of micro surgery in endodontics – Syngcuk Kim
Vasudev S.K et al, Root end filling materials – A review – JOE, 2003, 15, 11 – 18.
J. Camilleri et al, The constitution of mineral trioxide aggregate, 2005, 21, 297 – 303.
Niederman et al, A systematic review of invivo retrograde obturating material, IEJ, 2003, 36, 577 – 585.
Tagger et al, A standard for radiopacity of root end filling materials is urgently needed, IEJ, 2004, 37, 260 – 264.
Sousa et al, A comparative evaluation of the biocompatibility of materials used in apical surgery, , 37, 738 – 748.

109. thank u