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MICHAEL POSADA

ORTHODONTIC BRACKET MATERIALS

TYPES OF MATERIALS CERAMIC COBALT CHROMIUM COMPOSITE GOLD PLASTIC STAINLESS STEEL TITANIUM

METALLIC BRACKETS COMPOSITION: Base metal alloys such as: Stainless steel Cobalt-chromium-nickel (CoCrNi) alloy Nickel-titanium (NiTi) alloy -titanium (-Ti) alloy Pure titanium.

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STAINLESS STEEL Most orthodontic brackets Contains: 8% to 12% nickel (Ni) 17% to 22% chromium (Cr) Manganese (Mn) Copper (Cu) Titanium (Ti) Iron (Fe)

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FABRICATION TECHNIQUES: Casting Milling Metal Injection Molding (MIM)

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FABRICATION TECHNIQUES: Casting Most expensive 90% of the metal used is wasted in sprues and runners

Milling Moderately expensive 50% to 75% of the material used becomes scrap during machining

Metal Injection Molding (MIM) Least expensive Material savings during the production cycle because runners and sprues can be easily recycled and reused 1 1 Z i e l s, S . 2 0 0 5 . n i

WELDING / BRAZING Important step in fabrication process Used to put together various components to make the whole bracket

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WELDING / BRAZING Welding: Melting of additional material to join two materials

WELDING / BRAZING Brazing: Melting a lower-melting-point material between the materials to form a bond between them

BRAZING Brazing alloys: Silver Cu Zinc

These materials can corrode and releasing metals to the oral cavity Bracket less resistant to external forces

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BRAZING Incorporating higher proportions of: Cr Ni Molybdenum Ti

Lower amounts of: Sulfur Carbon

Increase the corrosion resistance of stainless steel products.9 G u rso y , S . 2005.

METAL INJECTION MOLDING PROCESS:1. Homogeneous mixture is obtained: Small size metal particles (few microns) Organic binders (wax, thermoplastic resins, and other materials), Lubricants Dispersants

2.

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METAL INJECTION MOLDING PROCESS:2. Injection of Mixture Injection molding machine The injected parts, called green parts, Parts are formed into the desired geometry 1722% oversize to compensate shrinkage after sintering

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METAL INJECTION MOLDING PROCESS:3 Debinding Removal of at least 90% of the organic binder from green parts Heat Solvent Both

The green parts are now have now brown parts Same size with a porous structure.

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METAL INJECTION MOLDING PROCESS:4 Sintering High-temperature furnace Under vacuum or a controlled atmosphere

Residual binder is removed Parts shrink by 1722% Reaching the precise desired dimensions Shrinkage is similar along the three axes.

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METAL INJECTION MOLDING

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BIOCOMPATIBILITY Many of the metallic alloys contain nickel, such as: Stainless steel Cobalt-chromium Nickel-titanium Beta-titanium

Nickel in orthodontic metallic biomaterials ranges: From 8% (as in stainless steel) To 50% (as in the nickel-titanium alloys)

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BIOCOMPATIBILITY Leaching of these metallic components may be a potential trigger to an allergic reaction. Due to the presence of this metal in the environment Ingestion or direct contact with the skin and/or mucosa.

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BIOCOMPATIBILITY Nickel-induced contact dermatitis: Type IV delayed hypersensitivity Occurring at least 24 hours after exposure

Tissue reactions: Intraoral diffuse red zones Blisters Ulcerations Eczematic and urticarial reactions of the face or more . 1 2 K o l ki a , O . E . 2 0 0 9distant skin areas. o th

BIOCOMPATIBILITY Microbial adherence: Adhesion of S. Mutans Weaker on metallic than on plastic and ceramic brackets

Metallic brackets had a lower potential for bacterial accumulation than plastic and ceramic brackets.

Oral hygiene and fluoride therapy for orthodontic patients is indispensable in order to maintain health.

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INDICATIONS If patient is not allergic to any of the component of which the metal bracket is made They are economic Reliable Strong

CERAMIC BRACKETS COMPOSITION: Polycrystalline Alumina Monocrystalline Alumina. More popular Also called sapphire brackets.

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CERAMIC BRACKETS New developments Improve of friction characteristics by combination of: Stainless steel Gold liner

placed in a polycrystalline alumina Bracket.

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CERAMIC BRACKETS New developments Study was conducted to evaluate their frictional characteristic: Under strictly regimented conditions, metallined ceramic brackets are not only esthetic but also possess competitive frictional characteristics.

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STRUCTURE AND PROPERTIES OPTICAL PROPERTIES: Depends on the size of the grain Large grain size = greater the clarity or translucency Polycrystalline alumina is translucent Monocrystalline alumina is transparent

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STRUCTURE AND PROPERTIES RESISTANCE TO FRACTURE: Grain size Big grain size particles = lower resistance to fracture

There is no shifting of atomic bonds and redistribution of stresses More brittle and have lower tensile strength than metals Tensile strength is dependent on:6 J h n so n , G . o 2005.

Thickness of the material Defects on the material surface

FABRICATIONTECHNIQUES: Machining:Subtractive method Entire crystal is milled with diamond tools to obtain the desired shape

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FABRICATIONTECHNIQUES: Additive:Sintering polycrystalline Alumina Special binders are used to thermally fuse the particles together.

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FABRICATION Manufacturing process Plays a very important role in the strength of a ceramic. Strength of a ceramic bracket is reduced by presence of: Pores Machining damage from milling Cracks

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DRAWBACKS OF CERAMIC BRACKETS Ceramic bracket fracture: Interface of the tie wing and base (Tie-wing complex) Most common site of fracture

DRAWBACKS OF CERAMIC BRACKETS Ceramic bracket fracture: Study was conducted to evaluate the most popular ceramic brackets Fracture strength of the tie-wing complex Tensile load is placed directly under the tie wing

DRAWBACKS OF CERAMIC BRACKETS Results: Most to least resistant to tensile fracture of the distoincisal tie wing1. Ormco Inspire (monocrystalline alumina) 2. Dentaurum Fascination 3. GAC Mystique 4. TP InVu 5. 3M/Unitek Clarity 6. American Orthodontics Virage 7. Rocky Mountain Luxi

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BIOCOMPATIBILITY Effect on the epithelial cells of the buccal mucosa: Study was conducted to test that metallic and ceramic brackets

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BIOCOMPATIBILITY Results: Placement of ceramic and metallic brackets in the buccal cavity induces cellular alterations These alterations do not suggest malignancy Buccal mucosa cells adjacent to the metal and ceramic brackets tend to return to the initial morphology after removal of the brackets

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BIOCOMPATIBILITY Microbial adherence to the ceramic bracket: Study was conducted to evaluate that property comparing metal, plastic and ceramic brackets. Results: The presence of any type of bracket may have little effect on the microbial populations that colonize orthodontic brackets in vivo. The presence of these cariogenic organisms on orthodontic brackets is real Oral hygiene and fluoride therapy for orthodontic patients is indispensable in 4 A n h o u ry , P. 2 0order to maintain health 02.

INDICATIONS Esthetics Severe allergies to metals

PLASTIC BRACKETS COMPOSITION: The early plastic brackets were made of: Polycarbonate Plastic molding powder

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PLASTIC BRACKETS COMPOSITION: The early plastic brackets problems: Decreased wear resistance Insufficient hardness Inability to withstand the torquing forces

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PLASTIC BRACKETS COMPOSITION: 3 ways to improve the mechanical properties of plastic brackets exist: Alternative polymers Chemical modifications of available polymers Fiber or filler reinforcement of polymers

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PLASTIC BRACKETS COMPOSITION: The reinforcements of polymers by addition of: Fillers (composites) Fibers Metallic inserts in the bracket slots

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BIOCOMPATIBILITY Polymer brackets were developed in response to: Enamel damage during debonding of ceramic brackets Safe debonding of plastic brackets: Low modulus of polymer appliances and a peel-off effect similar to that of metal brackets

Excessive wear of enamel surfaces on opposing teeth

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BIOCOMPATIBILITY Because orthodontic appliances remain in the mouth for a relatively long time Mechanical properties of the brackets play an important role Quantity and quality of bacterial accumulation on the bracket materials play decisive roles in their success or failure. A study was done which conducted that the there is no influence in the microbial adhesion due to the presence of polymer brackets.

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