Brackets are the most important elements of orthodontic appliance …or in simple words “it’s the tool that holds the wire” They are classified according to there size: large, mini, and ultramini. Base: maybe straight or curved Width: maybe narrow , medium, or wide Or they maybe single or twin according to the technique used.
A historical overview: The first attempt to scientifically move a tooth was made in 1728 by a French dentist , Pierre Fauchard. He used an arch-shaped metal band with holes drilled in preselected sites. This arrangement gave only tipping control, in one dimension, and soon proved inadequate for controlling rotations.
In 1860 Norman Kingsely introduced occipital anchorage, and then he published the “Treatise on oral deformities as a branch of mechanical surgery. In which he defended dental extractions for some orthodontic cases, which was a controversial issue at that time. Angel considered Kingsely the “greatest mastermind of orthodontics”
EDWARD HARTLEY ANGLE For the first third of this past century, orthodontics found itself dominated by one man, Edward H. Angle. Known as the father of modern orthodontics
In the 20th century ,Edward Angle devised the first simple classification system for malocclusions, and he introduced Edgewise appliance. In 1910 angle developed the pin and tube appliance, it had gold and platinum bands and attachments for most teeth.
But this appliance had many disadvantages, it was difficult to handle, to ensure that the force passed in the right direction through the roots of the teeth, the pins and tubes were assembled parallel to the long axis of the teeth and to each other, and to keep the appliance activated , it was necessary to keep changing the positions of the pins during treatment.. Plus it was not possible to obtain control of rotation with this appliance.
Angle stated that the ideal appliance would be the one that could provide light and continuous forces in the desired directions and according to that he then developed the ribbon appliance …which included a delicate metal device welded to the bands. This device was called a “bracket” by Angle. Ribbon arch
Therefore, the edgewise bracket did not suddenly spring full-grown from Angles fertile mind, but slowly evolved with several iterations Angles many iterations of the edgewise bracket:
The Edgewise Appliance, on which modern orthodontics appliances are based, has identical brackets for all teeth, and tooth movement was accomplished by adding bends to rectangular arch wires , which were held in the bracket slot using metal ligatures. The first brackets were made of gold, because of the softness of the gold they tended to lose their shape easily due to the forces generated by the occlusion and the ligature.
Edgewise appliance allowed movement of teeth in all directions…however rotation was still difficult to accomplish. Note: The Edgewise appliance was developed for treatment without extractions. This appliance supplied the needs of that time. Adward Angle died on August 11/1930 ….”I finished my work as perfect as it was possible to do it”
Angles influence continued until a student of his, Charles H. Tweed, had enough courage and objectivity to challenge Angles non-extraction scheme. He used the edgewise appliance , besides making extraction of teeth acceptable for orthodontic correction, he introduced the idea of anchorage as an important part of treatment.
In 1955, Levern Merrifield, one of Tweed’s most brilliant students, introduced improvements to Edgewise Appliance, making it easier to work with.
Paul Begg reviewed Angle’s views on diagnosis and then he embraced the concept of tooth extraction. He started using round arch wires in his treatments . He launched the Begg technique with angle ribbon appliance as a basses, but with the slot oriented to the gingival ( vertical slot)
In 1970, Lawrence Andrews, in attempt to eliminate the need for archwire bends, he developed the Straight-Wire Appliance. The concept behind this appliance was that the brackets would move the teeth in the desired direction.
Andrews designed a bracket system that had in its prescription angulation , inclination and in-out (Built-in features)
Note: The Straight-Wire appliance was initially developed for cases without extractions. However, it also started to be used for extraction cases, by incorporating the concepts of angulation, torque, and first order bend in to the brackets. (first generation )
Roth: Straight-Wire Technique Straight-Wire Appliance became widely accepted and one of the orthodontists who collaborated in its evolution was Ronald Roth. “ If you are not part of the solution, you are probably part of the problem.”
Roth tried to avoid the difficulties and he recommended the use of a single appliance system that consisted of minimum number of brackets for both extraction and non extraction cases. This system became the “second generation”
Brackets Material:The bracket material must be: Hygienic, nontoxic Resistant to corrosion It must resist forces applied to it by the wire. Esthetic Not absorb water Not be discolored by oral liquids Have minimal bracket-wire friction
TYPES OF BRACKETS:Metal brackets: SS brackets Most brackets currently used are made of austenitic stainless steel containing 18% chrome and 8% nickel SS brackets have most of the basic characteristics expected from a bracket. It is resistant to all kinds of corrosion, hygienic, and economical.
However it has 2 importantdisadvantages : Not esthetic May release nickel and chrome into the oral environment. Therefore, various alternative material have recently been developed to eliminate the esthetic problems , including ceramics, plastic, and composite materials.
PLASTIC BRACKETS: Initially made of polycarbonate and plastic molding powder (Plexiglas)These brackets did not last long because of their: Discoloration Fragility Breakage under stress Also, much of the energy in the wire was expended in distorting the brackets because of the poor integrity of the arch wire slot and therefore forces were not transmitted to the tooth.
They improved & reinforced plastic brackets by introducing : Precision- made stainless steel slot inserts ( TO MINIMIZE FRICTION) Ceramic fillers Ceramic-reinforced plastic brackets are suitable for clinical use because of there color stability , have lower friction, and have the structural integrity to transmit orthodontic forces without distorting.
CERAMIC BRACKETS: They are the esthetic alternative to plastic brackets. Made of monocrystalline and polycrystalline ceramic material.
Advantges: excellent color fidelity stain resistance biocompatible Hardness
Disadvantages: Fracture tendencies ( during torsional and tipping movements) Causes abrasion of opposing teeth They damage the enamel during the debonding procedure.
A new design of the ceramic bracket is borrowed from the design of the metal reinforced plastic brackets…in which a metal slot is incorporated in ceramic bracket. To reduce friction between bracket and wire. Another feature of this appliance is the ease of debonding via a vertical scribe line placed in the base of the bracket.
Surface modification of the brackets using photocatalytic titanium oxide: Orthodontic brackets coated with photocatalytic titanium oxide showed an antiadherent effect against L acidophilus compared with uncoated brackets. The bacterial mass that was bound to the TiO(2)- coated brackets was less when compared with the uncoated brackets. Furthermore, TiO(2)-coated brackets had a bactericidal effect on L acidophilus, which causes dental caries.
Surface Modification of Orthodontic Bracket Models viaIon Implantation: Effect on Coefficients of Friction In an effort to reduce the unwanted effects of friction, ion implantation of bracket models was accomplished (with nitrogen ,carbon and other materials) And it enhanced surface characteristics of the brackets and reduced the friction between the bracket and the wire.
Frictional and mechanical properties of diamond-like carbon-coatedorthodontic brackets This study investigated the effects of a diamond-like carbon (DLC) coating on frictional and mechanical properties of orthodontic brackets. DLC films were deposited on stainless steel brackets using the plasma-based ion implantation/deposition (PBIID) conclusion, the surfaces of metal brackets can be successfully modified by the PBIIB…therefore the DLC-coating process significantly reduces frictional forces.