Copy of biomaterials used in orthodontics /certified fixed orthodontic courses by Indian dental academy


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Copy of biomaterials used in orthodontics /certified fixed orthodontic courses by Indian dental academy

  1. 1. BIOMATERIALS USED IN ORTHODONTICS INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. CONTENTS    Introduction Classification Orthodontic Wires      Gold Alloy Wires Stainless Steel Wires Cobalt Chromium Nickel Wires Nickel Titanium Wires Newer Wires
  3. 3.  Orthodontic Brackets         Classification Stainless Steel Brackets Titanium Brackets Gold Coated Brackets Platinum Coated Brackets Nickel Free Brackets Ceramic Brackets Ceramic Brackets With Metal Slots
  4. 4.  Implants        Classification Titanium Implants Cements In Orthodontic Composites In Orthodontics Elastics In Orthodontics Impression Materials Conclusion
  5. 5. INTRODUCTION  Orthodontics need a variety of devices made form a large array of materials that in so far as possible must be harmless.  All substances are poisons. There is none which is not a poison. The right dose differentiates a poison from a remedy. – Paracelsus  Fewer branches of medicine match their dependence on materials.
  6. 6. THE GENERAL REQUIREMENTS FOR BIOMATERIALS : Non-toxicity  Strength  Hydrolytic stability  Reproducible Quality  Sterilizability 
  7. 7. CLASSIFICATION  Although there is absence of a definite classification of metals used in orthodontics, in general we may broadly classify them as  Orthodontic wires  Orthodontic Brackets  Orthodontic Implants  Orthodontic Instruments  Miscellaneous
  8. 8. ORTHODONTIC WIRES   They generate the required forces and movements to bring about tooth movement. Orthodontic wires are made from castings by drawing a cast metal through a die.
  9. 9. GOLD ALLOYS – WIRE  Prior to the 1950‟s precious metal alloys were routinely used for orthodontic purposes, this was mainly because alternate materials available would not tolerate the extracting intraoral conditions  The gold alloy wire compositions were generally similar to those of the type IV gold casting alloys.
  10. 10.  They are recognized by ADA specification no. 7 and are of two types  Type I  Type II : Relatively lesser content of gold 65% : Increased gold content 75%
  11. 11. ADVANTAGES      Excellent biocompatibility Easily joined by soldering Good formability Capable of delivering lower forces than stainless steel Excellent corrosion resistance
  12. 12. DISADVANTAGES  High cost  Low yield strength  Low spring back  Crozat appliance is still occasionally made from Gold, following the original design of the early 1900‟s.
  13. 13. STAINLESS STEEL  This is the most popular wire in orthodontics because of its low cost and possesses many qualities that is desired for orthodontic treatment.  Stainless steel is an alloy of iron. It was discovered accidentally by Sheffield metallurgist Harry Bearly during World War I days.
  14. 14.  It entered dentistry in 1919, introduced at Krupps dental polyclinic in Germany by F. Hemptmey who first used it to make a prosthesis and called the alloy Wipla (German: like platinum)  Angle used it in his last years as ligature wires  By 1937 the value of stainless steel as an orthodontic material had been confirmed.
  15. 15. COMPOSITION  Steels are iron based alloy that contain less than 1.2% carbon  When chromium is added to the steel, the alloy is called stainless steel  The stainless steel alloys used for orthodontic wires are of the 18-8 austenititic type containing approximately 18% chromium and 8% nickel
  16. 16.  Chromium has a „passivating effect on steel‟  Typically stainless steel orthodontic wires are fabricated from AISI (American Iron & Steel Institute) types 302 and 304 alloys
  17. 17. ADVANTAGES  Low cost of the wire alloys  Proven biocompatibility  Excellent formability for fabrication into orthodontic appliance  Can be soldered and welded (Welded joints may require solder reinforcement)
  18. 18. DISADVANTAGES  High force delivery  Low spring back  Susceptible to intergranular corrosion
  19. 19. OTHER STEELS INCLUDE  Duplex Steel:  It consists of an assembly of both austenite and ferritic grains  They contain molybdenum, chromium and lower nickel content  Includes properties of both like high yield strength, increased toughness & ductility
  20. 20.  When improperly heat treated there is a tendency to form a brittle phase called sigma phase which diminishes the corrosion resistance  Used for manufacturing of one piece brackets Eg: Bioline
  21. 21.  Manganese Containing Steel:  Manganese is known as a austenizing element. Manganese has been used as a replacement for nickel  Soft Stainless Steel:  It is thoroughly annealed to remove all the stresses incorporated during cold working. These are commonly used as ligature wires.
  22. 22.  Co-Ax Wires:  It has a central core wire for stability with five outer wires wrapped around for resilience and flexibility  Applies  Allows  One light continuous force brackets to slide freely of the most efficient wires available for edge wise or light wire techniques to align crowded or rotated anteriors
  23. 23.  Multi Stranded or Braided Wires:  Composed of specified numbers of thin wire sections twisted or braided around each other to provide round or rectangular cross section  Increases flexibility
  24. 24.  Can sustain large elastic deflection in bending
  25. 25.  Australian Arch Wires:  In 1952, Dr. Begg in collaboration with an Australian metallurgist Mr. A.J. Wilcock, developed a high tensile stainless steel wire that is heat treated and cold drawn to yield its now familiar and excellent clinical properties.
  26. 26.  It was made thin enough to distribute force at an optimal level for tooth movement over a considerable period of time, over long distance and with minimal loss of force intensity while doing so.  The diameter of the wire initially produced was progressively decreased from 0.018 to 0.014 inch.
  27. 27. THERE ARE 6 TYPES OF AUSTRALIAN ARCH WIRES:  Regular Grade (White label)  Lowest grade  Easiest to bend  Used for practice bending & forming auxiliaries
  28. 28.  Regular Plus (Green label)  Used for auxiliaries and arch wires when more pressure and resistance to deformation are desired  Special Grade (Black Label)  Highly resilient  Used for starting arch wires in many techniques
  29. 29.  Special Plus (Orange Label)  Highly resilient  Routinely used in deep bite correction  But bending is difficult as brittle
  30. 30.  Extra Special Plus Grade( Blue Label)  Also referred to as premium plus in Australia  This is unequalled in resiliency & hardness  More difficult to bend & more subjected to fracture  Extra special plus‟s ability to move teeth, open bites and resist deformation are excellent
  31. 31.  Supreme Grade (Blue label)  Further developed by Mr. A.J. Wilcock Jr. in 1982 on request of Dr. Mollenhauer of Australia  Is Ultra light tensile fine round stainless steel wire
  32. 32.  Was initially introduced in the 0.10” diameter and this was further reduced to 0.09” diameter  Is primarily used in early treatment for rotation, alignment and levelling  Although supreme exceeds the yield strength of extra special plus, it is intended for use in either short section or full arches where sharp bends are not required.
  33. 33. NEWER WILCOCK ARCH WIRES:  Recently A.J. Wilcock scientific and engineering company, the manufactures of this wire have introduced a new series of wire grade and sizes with superior properties by use of new manufacturing process called pulse straightening.
  34. 34.  The new grades available now are: - Premium .020” - Premium plus .010”, .011”, .012”, .014”, .016” .018” - Supreme .008”, .009”, .010”, .011”
  35. 35. COBALT – CHROMIUM – NICKEL WIRES (ELGILOY)  A Cobalt chromium nickel orthodontic wire alloy was developed during the 1950‟s by the Elgiloy Corporation.  They are available in four tempers or levels of resilience  But all four alloy tempers have the same composition.
  36. 36. COMPOSITION        Cobalt : 40% Chromium : 20% Nickel : 15% Carbon : 0.15% Iron : 15.8% Manganese & Beryllium Cobalt chromium alloys are available commercially as Elgiloy, Azura and Multiphase.
  37. 37.  Blue Elgiloy  It is the softest of the four wire temper and can be bent easily with fingers or pliers.  It is recommended for use when considerable bending, soldering and welding is required.  Heat treatment of blue elgiloy increases its resistance to deformation.
  38. 38.  An interesting clinical use of blue elgiloy wire is fabrication of the fixed lingual quad helix appliance which produces slow maxillary expansion for the treatment of maxillary constriction in primary and mixed dentition.
  39. 39.  Yellow Elgiloy  It is relatively ductile and more resilient than blue elgiloy. It can also be bent with relative ease. Further increase in its resilience and spring performance can be achieved by heat treatment.
  40. 40.  Green Elgiloy  It is more resilient than yellow elgiloy and can be shaped with pliers before heat treatment.  Red Elgiloy  Most resilient and has high spring qualities.  Heat treatment makes it extremely resilient.
  41. 41. NICKEL TITANIUM WIRES  The alloy was invented by William F Buehler and Associates in early 1960 and was developed for the space program for naval ordnance laboratory in Silver Springs, Maryland.  But has proved very useful in clinical orthodontics because of its exceptional springiness.
  42. 42.  Andreasen introduced the alloy to orthodontic profession in 1971 and its clinical use started in 1972.  Nickel titanium alloy marketed as Nitinol by 3M, Unitek, Monrovia, CA, USA.
  43. 43.  Niti alloys have remarkable properties that are unique in dentistry  Shape Memory  Super Elasticity
  44. 44. CLASSIFICATION OF NITI WIRES Kusy has classified Nickel titanium wires as:  Martensitic stabilized Alloys  These do not possess shape memory or super elasticity because the processing of the wire creates a stable Martensitic structure. Ex: Nitinol.
  45. 45.  Martensitic Active Alloys  These alloys employ the thermoelastic effect to achieve shape memory.  The oral environment raises the temperature of the deformed arch wire in martensite phase to transform into austenitic phase there by returning to the starting shape.
  46. 46.  This can be observed by the clinician if a deformed archwire segment is warmed in the hands. Ex: Neo Sentalloy and Copper Niti
  47. 47.  Austenitic Active Alloy:  These undergo a stress induced martensitic (SIM) transformation when activated. These alloys display superelastic behaviour.  An austenitic active alloy does not exhibit thermoelasitc behaviour when a deformed wire segment is warmed in the hands. Ex: Chinese Niti and Japense Niti
  48. 48. NITINOL  Work by Andreasen and colleagues led to the development of Nitionol: is of Martensitic stabilized Alloy form  It has excellent spring back  It does not possess super elasticity because they primarily follow the martensitic phase and its shape memory has been diminished by work hardening process.
  49. 49.  Provides a light force  It has high arch wire – bracket friction  Commercially referred as M- Niti
  50. 50. COPPER NITI  This is one of the most recent introductions in the family of Niti alloy wires.  It was introduced by Rohit Sachdeva and Suchio Mujasaki in 1994.
  51. 51. COMPOSITIONS     Nickel : 44% Titanium : 51% Copper : >5% Chromium : 0.2 – 0.3%
  52. 52. EFFECT OF COPPER ADDITION ON THE SUPER ELASTIC BEHAVIOUR BY GIL F J, PLANELL J A (JOURNAL OF BIOMEDICAL MATERIAL RESEARCH -1999)  Addition of copper narrows the stress hysteresis  It stabilizes the super elastic characteristics against cyclic deformation  Produces greater stability of both the transformation temperature
  53. 53.  It also reduces the ageing effect  Improves corrosion resistance  But addition of copper is associated with an increase in phase transformation temperature above that of the ambient value in mouth.  This necessitates addition of chromium.
  55. 55.  Corresponding to the austenite finish temperature (Af) for the completion of martensite to austenite transformation.  Shape memory behaviour is reported by the manufacturer to occur for each variant at temperatures exceeding the specified temperature.
  56. 56. USES OF COPPER NITI WIRES  27° C, Copper Niti generates forces in the high range of physiological force limits and produces constant unloading forces that can result in rapid tooth movement.  Engagement force is lower than with other super elastic wires.  This variant would be useful in mouth breathers.
  57. 57.  35° C, Copper Niti generates mid range constant force levels when the wire reaches mouth temperature.  Early ligation is easier with full size arch wires due to the lower loading forces.
  58. 58.  When earlier engagement of full size wires and sustained unloading forces at body temperatures are desired, 35° C, Copper Niti is the ideal wire.  The variant is activated at normal body temperature.
  59. 59.  40° C, Copper Niti provides intermittent forces that are activated when the mouth temperatures exceeds 40° C.  It is useful as an initial wire and can be used to engage severely malaligned teeth without creating damaging or painful levels of force or unwanted side effects.
  60. 60.  It is also the wire of choice for patients scheduled for long intervals between visits when control of tooth movement is a concern.  This variant would provide activation only after consuming hot food and beverages.
  61. 61. ADVANTAGES OF COPPER NITI OVER TRADITIONAL NITI ALLOYS  Copper Niti generates a more constant force over long activation spans than other Niti alloys  For very small activations, copper Niti generates near constant force unlike other Niti Alloys
  62. 62.  Copper Niti is more resistant to permanent deformation compared with other Niti Alloys  It Exhibits better spring back characteristics
  63. 63. CHINESE NITI  It was developed by Dr. Hua – Cheng Tien and Colleagues at the general Research Institute for Non – Ferrous Metals in Beijing.  It was reported by Burnstone in 1985
  64. 64.  Mechanical properties have been extensively studied by Dr. C. J. Burnstone and associates and have indicated that Chinese Niti archwire has several unique characteristics:
  65. 65. CHARACTERISTICS  It has more than 4.4 times the spring back of stainless steel wires and more than 1.6 times the spring back of Nitinol wire in all modes of deformation, tension, bending and torsion.
  66. 66.  It exhibits small differences at varying temperatures because the material components have lower transition temperatures.  It exerts a nearly constant force magnitude regardless of the amount of deflection.
  67. 67. ANGLE 1992 – RONG CHENG  Chinese Niti was bench tested and compared to six other Niti Wires  Chinese Niti wire demonstrated 100% recovery at a 90° bending angle in a bending test based on a 12.5 mm span and 19% permanent deformation in a torsional test after a 720° twist over a 25.4 mm span.
  68. 68.  It demonstrated excellent retentive memory among the memory wires  It has a long constant range of bending and torsional movements.  It offers a nearly constant force which is desirable in orthodontic application
  69. 69.  It possesses unique low stiffness, high spring back and super elasticity. At subsequent visits, the wire is simply retied to the brackets.
  70. 70. CLINICAL USES FOR CHINESE NITI  It has been successful in the treatment of patients with a variety of malocclusions  Appliances include straight wire procedures when teeth are badly malaligned  In situations where large deflections are required
  71. 71.  In appliances designed to deliver constant forces  Used in both children and adults in leveling and teeth alignment.
  72. 72. JAPANESE NI TI WIRES  Developed by the Furukawa Electric Co., Ltd. of Japan in 1978.  The unique features are excellent spring back, shape memory, super-elasticity.  The wire delivered a constant force over an extended portion during deformation & rebound.
  73. 73.  Japanese NiTi alloy wire, yields a significantly higher value of elastic modulus than the Nitinol wire.  Tensile testing - When the wire is stretched upto 2%, stress – strain curve is proportional.  But when the strain was increased upto 8%, there was no change in stress. This phenomenon is called as superelasticity.
  74. 74. BETA TITANIUM WIRES  Introduced BY BURSTONE AND GOLDBERG in 1980  Commercial name – TMA (Titanium Molybdenum Alloy)
  75. 75.  At temperatures above 1,625° F pure titanium rearranges into a body-centered cubic (BCC) lattice, referred to as the ''beta" phase.  With the addition of such elements as molybdenum or columbium, a titanium-based alloy can maintain its beta structure even when cooled to room temperature.  Such alloys are referred to as beta-stabilized titaniums.
  76. 76. COMPOSITION     Titanium – 77.8 % Molybdenum – 11.3 % Zirconium – 6.6 % Tin – 4.3 %
  77. 77.  A clinical advantage of - titanium is its excellent formability which is due to the BCC structure of beta stabilised titaniums  The addition of molybdenum to the alloy composition stabilises the high temperature BCC - phase of polymeric titanium at room temperature.  Zirconium and zinc - contribute to increased strength and hardness.
  78. 78. PROPERTIES OF    - TITANIUM - titanium wires have improved springback which markedly increases their working range Excellent formability High ductility
  79. 79.    Wire has a relatively rough surface due to adherence or cold welding Only wire that possesses the property of true weldability Absence of nickel makes it more biocompatible and hence these wires can used in nickel sensitive patients.
  80. 80.  Excellent corrosion resistance and biocompatibility due to the presence of a thin, adherent passivating surface layer of titanium oxide.
  81. 81. FRICTION AND - TITANIUM  Kusy et al ( AJO 1990) and several other authors - Beta titanium archwires produce highest friction owing to substantial cold welding or mechanical abrasion.  The surface of the titanium wire can become cold welded to the S.S bracket, making sliding space closure difficult
  82. 82. CLINICAL APPLICATION  Due to its unique and balanced properties, beta titanium wire can be used in a number of clinical applications.  For a given cross section, it can be deflected approximately twice as far as stainless steel wire without permanent deformation .This allows a greater range of action for either initial tooth alignment or finishing arches.
  83. 83.  Beta titanium is ductile, which allows for placement of tie-back loops or complicated bends.  High formability of -titanium allows the fabrication of closing loops with or without helices.  Allows direct welding of auxiliaries to an arch wire without reinforcement by soldering.
  84. 84. ALPHA TITANIUM WIRES The composition of - titanium is  Titanium  Aluminum  Vanadium – 90 % – 6% – 4%
  85. 85.  The alloy is different in that its molecular structure resembles a closely packed hexagonal lattice as against the BCC lattice of beta titanium.  The hexagonal lattice possesses fewer slip planes.  Slip planes are planes in a crystal that glide past one another during deformation.
  86. 86.  The more the slip planes, the easier it is to deform the material.  BCC structure has two slip planes while Hexagonal lattice has only one slip plane.  Thus the near - phase titanium alloy is less ductile than TMA
  87. 87. TIMOLIUM WIRES  New entry into the arena of titanium – based alloys.  Alloy with titanium, aluminum and vanadium as its components.  This alloy has a smooth surface texture, less friction at the archwire –bracket interface, and better strength than existing titanium based alloys.
  88. 88. Vinod Krishnan et al (Angle 2004)  Weld surface of timolium exhibited a smooth and symmetrical flow of the alloy, less surface distortions, and an intact weld surface.  Timolium with proper flow of weld flash uniformly on both sides, had better surface properties on surface evaluation.
  89. 89.  Timolium with its smooth surface, reduced friction, low modulus, and better strength can be considered an introductory breakthrough in clinical orthodontic practice.
  90. 90. TITANIUM NIOBIUM WIRES  This alloy has low spring back (equivalent to stainless steel) and is much less stiffer than TMA.  It is useful when a highly formable wire with low forces in small activations is required.
  91. 91.  It is recommended for use with finishing elastics and even though it feels soft and pliable, it possesses a resiliency after bending that is equal to stainless steel.
  92. 92. SUPERCABLE  Hanson combined the mechanical advantage of multistranded cables with material properties of super elastic wires to create a super elastic NiTi Coaxial wire.  This wire called super cable comprises of 7 individual strand woven together to maximize flexibility and minimize force delivery.
  93. 93.  Elimination of archwire bending.  More effective and efficient control of rotations, tipping and levelling mechanics with an 0.018'' arch wire at the beginning of the treatment.
  94. 94.  Flexibility and ease of engagement regardless of crowding  A light continuous force delivery  Minimal patient discomfort and fewer visits due to longer arch wire activation
  95. 95. COMBINED WIRES  Jose' L. Zuriarrain,, José M. Echeverría,, Javier del Valle (AJO-1996)  The key to success in a multi attachment straight wire system is to have the ability to use light tipping movements in combination with rigid translation and to be able to vary the location of either, at any time the need arises during treatment.  They used three specific combined wires for the technique; Dual Flex-l, Dual Flex-2, and Dual Flex-3 (Lancer Orthodontics).
  96. 96. DUAL FLEX-1  The Dual Flex-1 consists of a front section made of 0.016-inch round Titanal and a posterior section made of 0.016-inch round steel.  The flexible front part easily aligns the anterior teeth and the rigid posterior part maintains the anchorage and molar control by means of the "V" bend, mesial to the molars.  It is used at the beginning of treatment.
  97. 97. DUAL FLEX-2  The Dual Flex-2 consists of a flexible front segment composed of an 0.016 ´x 0.022-inch rectangular Titanal and a rigid posterior segment of round 0.018-inch steel.
  98. 98. DUAL FLEX-3  The Dual Flex-3, however, consists of a flexible front part of an 0.017 ´X 0.025-inch Titanal rectangular wire and a posterior part of 0.018 square steel wire.  The Dual Flex-2 and 3 wires establish anterior anchorage and control molar rotation during the closure of posterior spaces.  They also initiate the anterior torque. All wires have elastic hooks.
  99. 99. Dual Flex arch wires A. Dual Flex-1 (0.016 Titanal anterior section and 0.016 steel posterior section). B. Dual Flex-2. (0.016 × 0.022inch Titanal anterior section and 0.016-inch steel posterior section). C. Dual Flex-3. (0.017 × 0.025inch Titanal anterior section and 0.018 × 0.018-inch steel posterior section.)
  100. 100. (AJODO- 2007)–BY THEODORE ELIADES Orthodontic materials research and applications: Current status and projected future developments in materials and biocompatibility……  After the introduction of thermoelastic and niobium nickel-titanium archwires, a breakthrough in archwires, no major development has emerged in the past decade.
  101. 101.  Since the mid-1990s, 2 research teams working independently in the United States and Japan presented extensive evidence on the feasibility of esthetic polymeric wires.  This new product consists of a composite polymer matrix reinforced with fibers.  By varying the reinforcing fiber content of the composite matrix, the elastic modulus of these wires can be adjusted to the preferred range.
  102. 102.  Projected short-term future developments in archwires  Composite wires will be commercially available during the next several years if the industry finds that introducing them to the market will be profitable.  Shape-memory plastics for orthodontic use might be a viable alternative in the future
  107. 107. Orthodontic Bracket    This term was introduced by Dr. Edward Hartley Angle in 1916 when he devised the ribbon arch appliance. Raymond C. Thurow has defined bracket an orthodontic attachment secured to a tooth for the purpose of engaging on arch wire. The meaning of the term bracket, a simple rigid L shaped structure, one arm of which is fixed to a vertical surface, the other projecting horizontally to support a weight, as a shelf.
  108. 108. TYPES OF BRACKETS (BASED ON MATERIAL)  METAL BRACKETS  Stainless steel brackets  Gold-coated brackets  Platinum-coated brackets  Titanium brackets
  109. 109.  PLASTIC BRACKETS  Polycarbonate brackets  Polyurethane-composite brackets  Thermoplastic-polyurethane brackets
  110. 110.  CERAMIC BRACKETS  Monocrystalline alumina (Sapphire)  Polycrystalline alumina  Polycrystalline Zirconia (YPSZ)
  111. 111. STAINLESS STEEL BRACKETS  Brackets made of stainless steel are alloys formulated according to the American Iron and Steel Institute (AISI) in the austenitic classes 302, 304, 316, and 317.
  112. 112. OSHIDA & MOORE (AJODO 1997;112:69-79.)  The corrosion behavior of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel.  The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material.
  113. 113.  The 2205 stainless steel alloy has a duplex microstructure consisting of austenitic and deltaferritic phases and is harder and demonstrated less crevice corrosion than 316L alloy.
  114. 114.  This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires.
  115. 115.  MARTENSITIC STEELS (400 SERIES)  Used  in several nickel free brackets DUPLEX STEELS  These steels have been used for the manufacture of one-piece brackets (Eg: Bioline “low nickel” brackets).
  116. 116.  PRECIPITATION-HARDENABLE (PH) STEELS  These steels can be hardened by heat treatment, which promotes the precipitation of some elements added.  PH 17-4 stainless steel is widely used for “mini” brackets.  PH 17-7 stainless steel is used to manufacture Edgelock brackets (Ormco).
  117. 117. PARTS OF A DIRECT BONDING METAL BRACKET Bracket profile portion that bears the slot into which archwires are engaged Brazing layer attaches foil to the bracket profile Foil metal piece of varying thickness to which mesh is attached Mesh made of wires of different sizes which is attached to foil in either horizontal and vertical or diagonal configuration
  118. 118. METAL BRACKET BASE TYPES  MESH TYPE BASES  Foil mesh base  Mini mesh base  Micro mesh base  Laminated mesh base  Dyna bond base  Ormesh wide central  Supermesh MB base
  119. 119.  NON-MESH TYPE BASES  Micro-loc base  Dyna lock integral base  Micro etch base  Laminated perforated base  Peripheral perforated base  Laser structured base
  122. 122. TITANIUM BRACKETS  The problems of nickel sensitivity, corrosion, and inadequate retention have all been solved with the introduction of a new, pure titanium bracket (Rematitan-DENTAURUM) in 1995.  Its one-piece construction requires no brazing layer, and thus it is a solder- and nickel-free bracket.
  123. 123.  Titanium brackets were grayer in color and rougher in texture than the stainless steel brackets and imparts none of the metallic taste as seen in stainless steel brackets.  Titanium and titanium-based alloys have the greatest corrosion resistance of any known metals.
  124. 124.  Titanium also has low thermal conductivity, and thus alleviates the sensitivity to extreme temperature changes often experienced by patients wearing metal appliances
  125. 125. COMPOSITION  A commercially pure (cp) medical grade 4 Ti (designation DIN 17851-German standards) was used as the basis for the manufacture of titanium brackets.  The chemical composition is 99+% Ti and reportedly less than 0.30% iron, 0.35% oxygen, 0.35% nitrogen, 0.05% carbon, and 0.06% hydrogen.
  126. 126.  The brackets were machined out of forged and rolled profiles.  The marking and the structuring of the retentive base pads were done by a computer-aided laser (CAL) cutting process, which generates microand macro-undercuts
  127. 127. TITANIUM BRACKETS VS DIFFERENT WIRES  Kusy and Whitley et al (1998) evaluated the static and kinetic frictional coefficients of commercially pure titanium brackets in the passive configuration in the dry and wet states against stainless steel, nickel-titanium, and beta-titanium archwires.  The optical roughness of Ti brackets is greater than conventional Stainless steel brackets
  128. 128.  With regard to frictional coefficients (µ), the Ti bracket compares favorably against the conventional Stainless steel bracket for all couples evaluated with Stainless steel, Ni-Ti, and beta-Ti archwires at 34°C.  Ti brackets may be substituted for SS brackets in order to eliminate the potential allergen, Ni, from the oral cavities of some patients.
  129. 129. TITANIUM BRACKETS VS STAINLESS STEEL BRACKETS  Rupali Kapur and Pramod K. Sinha (AJO 1999) measured and compared the level of static and kinetic frictional resistance generated between titanium and stainless steel brackets.  Both 0.018 and 0.022 inch slot size edgewise brackets were tested with different sized rectangular stainless steel wires.
  130. 130.  Titanium brackets have different frictional characteristics compared with stainless steel brackets using similar wires.  Titanium brackets showed lower static and kinetic frictional force as the wire size increased.  Stainless steel brackets showed higher static and kinetic frictional force as the wire size increased.
  131. 131. GOLD-COATED BRACKETS  Recently gold-coated steel brackets have been introduced and rapidly gained considerable popularity, particularly for maxillary posterior and mandibular anterior and posterior regions.  Brackets are now available with 24 karat gold plating, plated with 300 micro inches of gold.
  132. 132.  Gold-coated brackets may be regarded as an esthetic improvement over stainless steel attachments, and they are neater and thus more hygienic than ceramic alternatives.  Patient acceptance of gold-coated attachments is generally positive.  Significant side effects in the form of corrosion or allergic reactions have not been observed clinically.
  133. 133. Commercially Available Gold -Coated Brackets Victory Series™ (3M UNITEK) ORTHOS GOLD (Ormco) Forever Gold 24K Gold Plated (American orthodontics)
  134. 134. PLATINUM COATED BRACKETS  A process in which four layers of gold and a select metal are ionically implanted into the Stainless steel bracket surface manufactures platinum-coated brackets.  The result is a bracket with five times the abrasion resistance of gold.
  135. 135.  A smoother, harder surface than stainless steel for reduced friction and improved sliding mechanics is achieved.  By combining platinum metal and an exclusive implantation process, a barrier has been created against the diffusion of nickel, cobalt, and chromium.
  136. 136.  Platinum has been found to be superior to all other known metals for the manufacture of brackets and has been chosen by the jewellary industry to comply with European Directive EN1811, which dictates strict standards on the emission of nickel
  137. 137. NICKEL – FREE BRACKETS  Made of Cobalt chromium (CoCr) dental alloy  One-piece construction (without solder) by metal injection molding technique  Laser structured bracket base for retention
  138. 138.
  139. 139.   Greek word “Keramikos” meaning “earthen”. Ceramics are materials which are first shaped and then hardened by heat. Form a broad class of materials that include precious stones, glasses, clays and metallic oxides.
  140. 140. Evolution of brackets in terms of esthetics Bands  Bonding coated metal brackets smaller stainless steel brackets  lingual orthodontics  Polycarbonate  Metal slots (Ceramic reinforced)  ceramic brackets Ceramic brackets – introduced in 1986.
  141. 141.  Ceramic brackets are composed of aluminum oxide .  Polycrystalline alumina & monocrystalline alumina are the two most common varieties.  Another category that is being developed is the Zirconium brackets
  142. 142.  Heating aluminium oxide to temperatures in excess of 2100 C. The molten mass is cooled slowly, and the bracket is machined from the resulting crystal.
  143. 143.    Manufactured by blending aluminum oxide particles with a binder, the mixture can be formed into a shape from which a bracket can be machined. (sintering process) Temperatures above 18000 C are used to burn out the binder and fuse together the particles of the molded mixture. Heat treated to remove surface imperfections and relieve stresses created by the cutting operation
  144. 144. Zirconia is a mineral extracted from beach sands of Australia.  The PSZ (Partially stabilized Zirconium) developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO) as a reliable highly stress-resistant material.  A remarkable quality of zirconia -based advanced ceramics is that wear actually makes the material stronger 
  145. 145.
  146. 146. Contemporary Glazed slot & Metal lined Ceramic Brackets Regular Inserted Glazed How Good are They ? (especially when it costs 600% more than SS Brackets and 25% more than Ceramic brackets!!)
  147. 147. Ceramic Brackets With Metal Slots VIRAGE (American Orthodontics) CLARITY (3M UNITEK) • These brackets deliver sliding mechanics not found in conventional ceramic brackets. • There is no metal to ceramic friction resulting in smooth and bracket movement along the arch wire
  148. 148. Aspire & Inspire ASPIRE GOLD - KERAMIK BRACKET- Gold-Sliding-Guide F O R E S TA D E N T ® Illusion + Orthorganisers
  149. 149. Inspire - Ormco Mystique-Ceramic-glazed slot (GAC) Inspire - Ormco
  150. 150.
  151. 151.
  152. 152.  Ceramics have highly localized, directional atomic lattice that does not permit shifting of bonds and redistribution of stress. So when stresses reach critical levels, interatomic bonds break, and “brittle failure” occurs.
  153. 153.  Fracture toughness in ceramics is 20 to 40 times less than in stainless steel, making it much easier to fracture a ceramic bracket than a metallic one. Among ceramic materials, polycrystalline alumina presents higher fracture toughness than singlecrystal alumina.
  154. 154. Mean bond strengths of Clarity brackets (polycrystalline) and Inspire brackets (monocrystalline) found to be comparable. No enamel damage was evident in any specimen when the brackets were removed with the appropriate pliers recommended by the manufacturers. ( Sadowsky, AJO 2004).
  155. 155.  Stainless steel brackets generate lower frictional forces than ceramic brackets, because of their lower surface roughness, which is clearly visible when comparing scanning electron micrographs.  Ceramic brackets produce significant greater friction. Beta-titanium and nickel-titanium wires are associated with higher frictional forces than stainless steel or cobalt-chromium wires. Progressively increasing frictional values: stainless steel bracket, ceramic bracket with a metal reinforced slot, and traditional ceramic bracket with a ceramic slot. (Cacciafesta et al, AJO2003; Nishio et al. AJO 2004)
  156. 156.  Mono-crystalline alumina brackets are smoother than polycrystalline samples, but their frictional characteristics are comparable.( Kusy AJO1994)  To reduce frictional resistance, development of ceramic brackets with smoother slot surfaces, rounding of slot base or consisting of metallic slot surfaces has been accomplished.  Metal-lined ceramic brackets can function comparably to conventional stainless steel brackets and 18-kt gold inserts appear superior to stainless steel inserts. (Kusy & Whitley, Angle 2001).
  157. 157.  Ceramic brackets hold a definite advantage over plastic attachments, but some polycrystalline brackets do stain. This is due to individual diets – prolonged use of caffeine (coffee, tea, colas) for example, or hygiene practices (certain mouthwashes), or lipstick, but may also be associated with the type of bonding resins used.  Solution: Avoid excessive use of staining substances and, perhaps, select least-discoloring resins  Ceramic brackets may look discolored when the brackets themselves stain (direct discoloration) or when stains on the teeth or bonding resin show through the bracket (indirect discoloration). It tends to occur with polycrystalline brackets Using two-base resins, which tend to discolor less than no-mix one-step bonding resins, has been advocated
  158. 158.   The introduction of ceramic brackets was a much-heralded development in the orthodontic treatment of adult patients. Their acceptance by these patients has been unprecedented in the practice of orthodontics and contributed significantly in the expansion and development of contemporary orthodontic therapeutic modalities. However, there is still scope for improvement in some of the bracket characteristics before they are able to largely replace the use of metallic brackets, in the manner that direct bracket bonding replaced banding of teeth!!
  159. 159. Other non metallic brackets Composite brackets: Manufactured in two ways…. 1.Solid block of composite is shaped by cutting it into the desired form 2.Manufactured in a single cast which are specific for each tooth…… • • these are more smooth and comfortable to the patients don‟t degrade easily or distort under ligation or arch wire pressure unlike the cut brackets Some manufacturers recommend a primer coating of the base for bonding eg. Masel *composite bracket series named quantum requires a plastic primer Whereas , ORMCO’s Spirit MB recommend simple application of any adhesive material of choice for bonding.
  160. 160. PLASTIC BRACKETS They were a low cost alternative to expensive ceramic brackets . To eliminate friction between the arch wire and the bracket , these brackets were later introduced with metal slots. Frequent disadvantages encountered are staining , discolouring and low strength .
  161. 161. IMPLANT  A dental implant is a device of biocompatible materials placed within or against the mandibular or maxillary bone to provide additional or enhanced support for a prosthesis or tooth.
  162. 162.  Implants are an excellent alternative to traditional orthodontic anchorage methodologies, and they are a necessity when dental elements lack quantity or quality, when extraoral devices are impractical, or when noncompliance during treatment is likely.
  163. 163.  The growing demand for orthodontic treatment methods that require minimal compliance, particularly by adults, and the importance placed on esthetic considerations by all patients have led to the expansion of implant technology
  164. 164. ORTHODONTIC IMPLANTS  3 Categories –  Biotolerant (stainless steel, chromium-cobalt alloy),  Bioinert (titanium, carbon),  Bioactive (hydroxylapatite, ceramic oxidized aluminum). (AJODO – June 2005)
  165. 165.  Commercially pure titanium is the material most often used in implantology.  It consists of 99.5% titanium, and the remaining 0.5% is other elements, such as carbon, oxygen, nitrogen, and hydrogen.  Titanium is considered an excellent material
  166. 166. CEMENTS
  167. 167. CEMENTS Zinc Phosphate Cements  Zinc Polycarboxylate Cements  Zinc Silicate Cements  Glass Ionomer Cements And Its Modifications 
  168. 168. ZINC PHOSPHATE CEMENT This is widely used for cementation of orthodontic bands.  Composition: Powder: Liquid:  -Zinc oxide: 90 per. - Phospho. acid: 45-60 per. -Magnesium oxide: 10 per. - Water : 30-55 per. -Silica or Alumina : small amount - Aluminium : 2-3 per. - Zinc : 0-8 per.
  169. 169. Magnesium oxide results in improvement of mechanical properties as well as color stability.  Powder-liquid ratio strongly affects the working and setting times. A thin consistency is essential when the cement used as luting agent, to ensure adequate flow during cementation of orthodontic bands.  Working time: between 3 to 6 minutes.  Setting time: between 5 to 9 minutes. 
  170. 170. ZINC POLYCARBOXYLATE CEMENT It was introduced by Smith in 1968.  This was the first dental material developed with adhesive potential to enamel and dentin.  They combine the desirable properties of zinc phosphate and zinc oxide eugenol cements. 
  171. 171. COMPOSITION AND CHEMISTRY  Liquid: Polyacrylic acid or a copolymer of acrylic acid with other unsaturated carboxylic acid such as itaconic acid.  Powder: Composition and manufacturing of polycarboxylate cement are same as zinc phosphate.
  172. 172. WORKING AND SETTING TIME  The working time is,2.5 minutes as compared to 5 min for zinc phosphate.  Cooling the glass slab can cause the polyacrylic acid to thickness and which makes increased viscosity making mixing procedure more difficult.  The setting time range from 6 to 9 minutes, which is acceptable range for a luting cement.
  173. 173. ZINC SILICATE CEMENT This cement is a hybrid resulting from the combination of zinc phosphate and silicate powders. Also termed as silicate zinc.  Type I: Cementing media.  Type II: Temporary posterior filling material.  Type III: Used as dual purpose cement for cementing purposes and as temporary post filling material. 
  174. 174. COMPOSITION POWDER  Silica  Zinc oxide  Magnesium oxide  Fluoride 13.25% LIQUID Phosphoric acid 50% Zinc salts 4-9% Aluminium salts
  175. 175. • SETTING TIME is 3-5 minutes. • Mixing time is 1 minute. • Due to presence of fluoride, it imparts anticariogenic effect. It exhibit semitransulcency for cementation purposes. • Ph is less than that of zinc phosphate and hence varnish protection for pulp is indicated .
  176. 176. GLASS IONOMER CEMENT : Glass Ionomer is the generic name of a group of materials that use silicate glass powder and as aqueous solution of polyacrylic acid.  This materials acquires its same from its formulation of a glass powder and an ionomeric acid that contains carboxyl groups.  It is also referred to as “Polyalkenoate cement” 
  177. 177. The cement produces a truly adhesive bond to tooth structure. The use of GICs has broadened to encompass formulations as luting cements, liners, restorative material for conservative class I and class II restorations and core buildups and pit and fissure sealant. There are 3 types of GICs based on formulation and potential uses. Type I – for luting cement. Type II – restorative material. Type III – use as liner or base. Light curable versions of GICs are also available, because of the need for incorporating light curable resin in formulation, this type is also called “resin-modified GICs” or “compomers.”
  178. 178. ADVANTAGES Compressive strength greater than zinc phosphate.  An adhesiveness to enamel, dentin, and cementum.  Compatibility with the oral tissues.   Ability to leach fluoride
  179. 179. DISADVANTAGE Brittleness.  Low tensile strength.   Esthetic problems due to insufficiency translucency
  180. 180. COMPOSITION The glass ionomer powder is an acidsoluble calcium fluoroaluminosilicate glass.  The raw materials are fused to a uniform glass by heating them to a temperature of 1100 degrees centigrade to 1500 degrees centigrade. Lantanum, strontium, barium, or zinc oxide additions provide radiopacity. The glass is ground into a powder having particles in the range of 20 to 50um.
  181. 181. COMPOSITIION OF GLASS IONOMER CEMENT POWDER CONTENTS weight % Sio2 41.9 Al2 O3 28.6 AlF3 1.6 CaF2 15.7 NaF 9.3 AlPO4 3.8
  182. 182. LIQUID    Originally, it was aqueous solutions of polyacrylic acid in concentration of 50%. The liquid was quite viscous and tended to gel over time, now copolymer with itaconic, maleic, and tricarboxylic acid are used.. These acids increase the reactivity of the liquid, decrease the viscosity and reduce the tendency for gelation. Tartaric acid improves handling characteristics and increases working time; however, it shortens the setting time. To extend the working time, one glass ionomer formulation consists of freeze-dried acid powder in one bottle and water or water with tartaric acid in another bottle as the liquid component.
  183. 183.  When the powders are mixed with water, the acid dissolves to reconstitute the liquid acid. The chemical reaction then proceeds in the same manner as traditional powder liquid system. These cements have a longer working time with a shorter setting time. They are referred as “water settable GICs” also wrongly as anhydrous GICs.
  184. 184. WORKING TIME: The setting time depending on brands is usually between 5-9 minutes.  The mixing time should not exceed 45 to 60 seconds. At this time, the mix should have a glossy surface.  The recommended P:L ratio is in range of 1.25 to 1.5g of powder per 1mL of liquid. 
  185. 185. RESIN-MODIFIED GLASS IONOMER CEMENT    Moisture sensitivity and low early strength of GICs are the results of slow acid base setting reactions. Some polymerizable functional groups have been added to the formulations to impart additional curing process that can over come these two inherent drawbacks and allow the bulk of the material to mature thorough the acid-base reaction . Both chemical-curing and light-curing products are available. This group of materials have been identified with several names including light cure GICs, dual cure GICs( for light-cured and acid-base reaction), tricure GICs (dual cure plus chemical cure), resin– ionomers, compomers, and hybrid ionomers. None of the terms can truly describe the group of materials. We can use the term resin-modified GICs until a universal term is adopted.
  186. 186. COMPOSITION AND SETTING REACTION     The powder component of a typical light cured material consists of ion-leachable glass and initiator for light or chemical curing or both. The liquid component usually contains water, polyacarylic acid or polyacarylic acid with some carboxylic groups modified with methacrylate and hydroxyethyl methacarylate monomers. The last two ingredients are responsible for the unique maturing process and the final strength. To accommodate the polymerizable ingredients the overall water content is less for this type of material.
  187. 187. PHYSICAL PROPERTIES    Variation of properties from conventional glass ionomer can be attributed to the presence for polymerizable resins and lesser amount of water and carboxylic acids in liquid. The most notable one is probably the reduction for translucency of resin-modified material because of a significant difference in the refractive index between powder and set resin matrix. These materials release levels of fluoride comparable to those of conventional GICs.
  188. 188. STRENGTH  The diametral tensile strengths of resinmodified glass ionomer are higher than those of conventional GICs.
  189. 189. COMPOMERS Band LPPok: a two paste dual cure adhesive. UltraBand Lok: a single paste light cure adhesive. The first products used for band cementation were polycarboxylate, and zinc phosphate, recently GICs became popular because they could be used in a wet environment, release fluoride and have high compressive strength. None of these cements, however, bond chemically to metal, which means that cement cleanup often tedious and time consuming because adhesive stays bonded to the tooth rather than remaining in band when band is removed. The newer compomers even bond chemically to band material than zinc phosphate or GIC.
  190. 190. TECHINQUE  The bands should be roughened lightly with a fine diamond bur or microetcher. Tooth should be prophied, flossed, rinsed, dried, and isolated. Then if two paste dual cure adhesive is used the equal parts of pastes is placed on mixing pad, with 1 inch of paste 4 bands can be banded to the teeth. The two portions of adhesive are mixed for 10 seconds, and then the internal side of band covered in cement. The band is seated and excess adhesive is removed before the material is light cured.  Non-tooth colored band cements in blue and pink color are available for clean up process after the bands are removed.  Before mixing the cement metal instruments are wiped in was or cooking spray can be applied to the same.
  191. 191. COMMERICAL NAMES OF GIC Fuji  Ortho LCTM  GC America  Ketac  ESPE 
  194. 194. COMPOSITES
  195. 195. UNFILLED RESINS USED LATE 1960’3 THROUGH EARLY 1970’S  Advantages - tooth coloured - did not wash out - highly polishable - moderately strong  Disadvantages - not colour stable - shrinkage/leakage
  196. 196. COMPOSITE RESINS USED SINCE EARLY 1970’S  Advantages - tooth coloured - stain resistant - polishable - can be bonded to tooth - strong - wear resistant  Disadvantages - shrinkage (2-5%) - longevity??
  197. 197. CLASSIFICATION OF COMPOSITE RESINS BY PARTICLE SIZE macrofil microfil hybrid micro-hybrid Adaptic Heliomolar TPH Point 4 Concise Perfection Prodigy EsthetX Glacier Filtec Supreme TPH3
  198. 198. CLASSIFICATION OF COMPOSITE RESINS BY PARTICLE SIZE macrofil microfil (1960‟s) (1974) hybrid (1980) monomer Bis-GMA Bis-GMA Bis-GMA filler quartz silica Ba glass filler size(mu) 20-25 0.04 0.04-3 % volume 64 40 58 % weight 78 56 70-80 cure chem light light micro-hybrid (1995) Bis-GMA+ 5-75nm ? 75 light Nano-hybrids (extremely small filler particles) technology introduced in 2000
  199. 199. COMPOSITE RESIN COMPONENTS Monomer: Bis-GMA, Bis-EMA, UDM, TEGMA  Filler: silicate glass, Ba glass, quartz  Silane coupling agents  Tints (oxides)  Stabilizers  Initiators (peroxide, camphorquinones) 
  200. 200. COMPOSITE RESIN FUNCTION OF A FILLER Strength  Wear resistance  Esthetics  Radiopacity  Reduces shrinkage, thermal expansion, heat, swelling, and cost. 
  201. 201. COMPOSITE RESIN SURFACE VOIDS (% TOTAL SURFACE AREA) material activation % voids Hybrid Microfill Macrofil light light chemical 1.7 2.9 10-26
  202. 202. COMPOSITE RESIN WAYS OF CURING  Self-cure (chemical) - 2-paste system  Visible-light cure (VLC) – light initiated (470-480 nm)  Dual-cure – capable of both self-cure and VLC
  203. 203. COMPOSITE RESIN VLC – FACTORS THAT WILL AFFECT CURE Wave length of light (470-480 nm)  Strength of the light (350mw/cm2 minimum)  Distance from the composite resin  Exposure time  Colour of resin  Size of filler particle  Angle light enters composite resin 
  204. 204. LIGHT-CURING OF COMPOSITE TYPE OF LIGHT SOURCES AND CURE TIMES     Halogen light (normal method) (30 secs.) Plasma Arc lights (3-4 secs) LED (light emitting diode) (30 secs.) ** Laser (several secs.) ** LED will not cure all resin types due to a more restricted wave length spectrum coverage. Lighter C.R. and some flowable resins will not cure. (need camphor quinone)
  205. 205. LIGHT-CURING OF COMPOSITE TYPE OF LIGHT SOURCES AND COST Halogen light ($700 - $2000)  Plasma Arc lights ($4,000 - $6,000)  LED ($1000 - $2000)  Laser ($20,000 - $30,000 ?) 
  206. 206. LIGHT-CURING OF COMPOSITE HEAT PRODUCED DURING CURE Halogen light  Plasma Arc lights  LED  Laser  1.8 *C 8.4 *C 0.8 *C (?) Heat is related to the speed of the chemical reaction (cure) as well as the physical heat created by the curing unit.
  207. 207. LIGHT-CURING OF COMPOSITE TYPES OF CURE Full power cure - (intensity of light is uniform)  Pulse cure - ( light source turns on and off)  Step cure - (step-like increase of intensity)  Soft cure - ( 10 sec. cure, then delay minutes before finishing cure)  Ramp cure – gradual increase of light intensity 
  208. 208.
  209. 209. Elastomers is a general term that encompasses materials,that after substantial deformation, rapidly return to their original Dimension. Early advocates of natural rubber elastics in orthodontics included Barker , Case and Angle . Synthetic polymers are very sensitive to the effects f free radical generating systems i.e. ozone and ultraviolet light… The exposure to free radicals result in a decrease in the flexibility and tensile strength of the polymer. Manufacturers have added antioxidants and antiozonates to retard these effects and extend their shelf life.
  210. 210. 1.Latex and latex based systems – elastics plain colored 2.Polyurethane based systems plain colored fluoride releasing non fluoride releasing 3.Silicon based positioners
  211. 211. ELASTICS : Anterior posterior tooth movements including anterior retraction , mesial molar movement , correction of class II or class III occlusion , closure of extraction spaces Correction of overbite and over jet during retraction of anteriors, correction of posterior cross bites ,are a joint influence of the arch wires and the elastics,with the elastics contributing to the preponderance of force.
  212. 212. Elastomeric chains : Introduced to the dental profession in the 1960s Generates light continuous forces for canine retraction , diastema closure , rotational correction and arch constriction. Inexpensive, relatively hygenic,easily applied and requires little or no patient cooperation. Disadvantages: When extended and exposed to the oral cavity they absorb water and saliva and permanently stain and suffer a breakdown of internal bonds that leads to permanent deformation. Also experience rapid loss of force due to stress relaxation , resulting in a gradual loss of effectiveness. This makes it difficult for the orthodontists to determine the actual force transmitted to the dentition.
  213. 213. Elastomeric Modules : Can be distracted or extended to deliver light forces , but the degree of distraction required to deliver a force compatible with the physiologically sound tooth movement is still not completely characterized. Recently neon colored elastics have become popular among the young patients. Study by HOLMES et al however showed that neon colored elastics had no undesirable effects
  214. 214. Fluoride releasing elastomeric ligature ties containing tin fluoride (SnF2) are currently available to orthodontists Manufacturers claim that a low concentration of fluoride releases from these elastomerics over a sustained period of time : this could decrease plaque formation and in reminerelization of enamel around the bracket bases that are difficult areas to keep clean .
  215. 215. Fluoride containing elastomeric ligature ties released significant amounts of fluoride ; this was characterized by an initial burst of fluoride during the first 2 days and was followed by a logarithmic decrease over the remainder of the 6 month test period. It was estimated that adequate amounts of fluoride was released over the test period in order to theoretically aid in the prevention of demineralization and enhancement of reminerelization of enamel. William A Wiltshire .fluoride release from orthodontic elastomeric ligature ties . Am J Orthod Dentofacial Orthop 1999 ;115:288-92
  217. 217. In orthodontics we require impression materials that are elastic since we deal with dentulous patients The most commonly employed materials include I. Hydrocolloid – Agar Agar (reversible) - Alginate (irreversible) II. Elastomeric impression materials.
  218. 218. IRREVERSIBLE HYDROCOLLOID ALGINATE (ADA no 18) At the end of 19th century the chemist from Scotland noticed that certain brown seaweed produced a mucous extraction that he termed as „ALGIN‟. This became the chief ingredient in our popularly used dental ALGINATE, which is A SODIUM SALT ANHYDRO-ß-D-MANURONIC ACID/ ALGINIC ACID
  219. 219. In orthodontics we require impression materials that are elastic since we deal with dentulous patients The most commonly employed materials include I. Hydrocolloid – Agar Agar (reversible) - Alginate (irreversible) II. Elastomeric impression materials.
  220. 220. The factors causing its successful use as an impression material include: • Ease of manipulation • Comfortable to the patients • Relatively inexpensive not requiring elaborate armamentarium. TYPES TYPE I – RAPID SETTING TYPE II – NORMAL SETTING
  221. 221. COMPOSITION NO COMPOSITION FUNCTION % I. Salt of Alginic acid Dissolves in water & reacts with calcium ions 15% II. Calcium sulphate Reacts with pottasium alginate to form calcium alginate 16% III. Tri sodium phosphate Reacts in preference with calcium sulphate - retarder 2% IV. Pottasium Titanium Gypsum hardener 3% V. Zinc oxide Filler 4% VI. Diatomaceous earth Filler 60% VII. Flavouring & coloring agents Makes the material more palatable TRACES
  222. 222. PROPERTIES:• Setting time FAST setting 1 to 2 minutes REGULAR setting 2 to 4.5 minutes Range being from 1 to 5 minutes • FLEXIBILITY 14% at stress of 1000 gm/cm2 • ELASTICITY RECOVERY 97.3% , less than Agar Agar. • STRENGTH Compressive strength 5000-8000 gm/cm2 Tear strength 350 – 700 gm/cm2 • The shelf life of the material is short so it should be stored in a cool dry area to ensure against any moisture contamination
  223. 223. NON AQUEOUS ELASTOMERIC IMPRESSION MATERIAL (ADA no 19) They are liquid polymers and can be converted to rubber at room temperature by mixing with a suitable catalyst they undergo polymerization and or cross linking by condensatation/addition reactions to produce a firm elastic solid.
  226. 226. CONCLUSION   Advancements in orthodontic materials have had an impact in orthodontic practice, with prominent effects in mechanotherapy and biomechanics research. The search for efficient materials and convenient techniques to shorten treatment times has made significant progress and the future outlook of orthodontic practice will change notably. However, the assessment of biocompatibility of materials must also evolve to incorporate aspects of the biologic properties of materials, which will not be confined to in-vitro cytotoxicity assays.
  227. 227. People no longer like to see their smiles dotted with flashy stainless steel brackets instead they prefer a more discreet and aesthetically pleasing means of treatment. Even though there is a feeling that non-metallic arena is being neglected in the development process of newer products it actually is not the case. Newer products in the form of aesthetic brackets , nonmetallic wires and better luting materials are flooding the market. Because wide arrays of metallic, ceramic and polymeric materials are used in the profession, and new materials are continuously being introduced it is essential that the scientific bases for the selection and proper use of materials for clinical practice be thoroughly understood.
  228. 228. REFERENCES         Orthodontic Materials : William A. Brantley Science Of Dental Materials: Skinners Contemporary Orthodontics: Profitt W. Current Principles And Techniques: Graber and Vanarsdal Laboratory And Clinical Analysis Of Nitinol Wire: Andreasen GF ( AJO-1978) Beta Titanium, A New Orthodontic Alloy: Burstone CJ (AJO1980) Chinese Niti Wire, A New Orthodontic Alloy: Burstone CJ(AJO-1985) Elastic Property Of Nickel Titanium Wire For Orthodontic Use: Fujio Miura et al (AJO-1983)
  229. 229. REFERENCES      Japanese Niti Alloy Wire, Use Of Direct Electric Resistance Heat Treatment: Fujio Miura et al ( EJO-1988) Comparison Of Elastic Properties Of Nickel Titanium And Beta titanium arch wires: Kusy R.P.( AJO-1982) Mechanical Properties And Clinical Application Of Orthodontic Wires: Kapila And Rohit Sachdeva (AJODO1989) Effect Of Copper Addition On The Super Elastic Behaviour : Gil F J, Planell J A (Journal Of Biomedical Material Research 1999) Optiflex Archwire Treatment Of Skeletal Class III Open Bite: Talass MF (JCO-1992)
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