The development of contemporary fixed appliance

Presented byDr. Sharmin SultanaBDS, FCPS Part II TraineeDept of Orthodontics and Dentofacial OrthopedicsDhaka Dental College and Hospital

INTRODUCTION

Even the ancient Egyptians (3000 Bc) were concerned with straightening teeth, as mummies have been found to have crude metal bands wrapped around individual teeth with catgut to close spaces.

But regulation of teeth, as orthodontic alignment was formerly referred to, did not gain significant attention until Pierre Fauchard (1678-1793) French, who is considered the “FATHER OF MODERN DENTISTRY”, he wrote a book which name was ‘THE SURGEON DENTIST’ which had one entire chapter about orthodontics. And he first documented the cases with his appliance known as FAUCHARD’S BANDEAUOR BANDOLET in 1728.

FAUCHARD’S BANDEAUOR BANDOLETThis was the first expansion appliance, consisting of a heavy maxillary labial arch of precious metal to which teeth were ligated. It looks like a bow, affixed to external surfaces of teeth. This was the forerunner of modern arch wire.

As dentistry developed in the eighteenth and nineteenth centuries, a number of devices for the "regulation" of the teeth were described by various authors and apparently used sporadically by the dentists of that era.

After 1850, the first texts that systematically described orthodontics appeared, the most notable being Norman Kingsley's Oral Deformities. Kingsley, who had a tremendous influence on American dentistry in the latter half of the nineteenth century, was among the first to use extraoral force to correct protruding teeth. He was also a pioneer in the treatment of cleft palate and related problems.

In order to make good prosthetic replacement teeth, it was necessary to develop a concept of occlusion' and this occurred in the late 1800s. As the concepts of prosthetic occlusion developed and were refined, it was natural to extend this to the natural dentition. Edward H. Angle whose influence began to be felt about 1890, can be credited with much of the development of a concept of occlusion in the natural dentition. His increasing interest in dental occlusion and in the treatment necessary to obtain normal occlusion led directly to his development of orthodontics as a specialty, withhimself as the "father of modern orthodontics”

Angle's Progression to the Edgewise appliance:

Edward Hartley Angle's position as the "father of modern orthodontics“ is based not only on his contributions to classification and diagnosis but also on his creativity in developing new orthodontic appliances. With few exceptions, the fixed appliances used in contemporary orthodontics are based on Angle's designs from the early 20th century. Angle developed four major appliance systems: 1. E-arch 2. Pin and Tube 3. Ribbon arch 4. Edgewise appliance

In the late 1800s, Angle's first appliance the E-arch.

Basic design:a typical orthodontic appliance depended on some sort of rigid framework to which the teeth were tied so that they could be expanded to the arch form dictated by the appliance.

Bands were placed only on molar teeth, and a heavy labial archwire extended around the arch.

The end of the wire was threaded, and a small nut placed on the threaded portion of the arch allowed the archwire to be advanced so that the arch perimeter increased.

Individual teeth were simply ligated to this expansion arch.

Disadvantages:The E-arch was capable only of tipping teeth to a new position. It was notable to precisely position any individual tooth. It can deliver only heavy interrupted force.

1.E-Arch:

2. Pin and Tube: First appliance that employed a bracket

and used bands on most of the teeth. Angle began placing bands on other

teeth and used a vertical tube on each tooth into which a soldered pin from a smaller arch wire was placed.

With this appliance, tooth movement was accomplished by repositioning the individual pins at each appointment.

It was theoretically capable of great precision in tooth movement, it proved impractical in clinical use.

Disadvantages: An incredible degree of

craftsmanship was involved in constructing and adjusting this pin and tube appliance.

Relatively heavy base arch meant that spring qualities were poor.

Many small adjustment were needed.

It is said that only Angle himself and one of his students ever mastered the appliance.

3. Ribbon Arch: Angle attemted to achieve three axis control of tooth movement when he introduced the Ribbon Arch in 1916. Angle's next appliance modified the tube on each tooth to provide a vertically positioned rectangular slot behind the tube. A ribbon arch of 10 x 20 gold wire was placed into the slot and held with pins.The ribbon arch was an immediate success, primarily because the arch wire, unlike any of its predecessors, was small enough to have good spring qualities and was quite efficient in aligning malposed teeth. Although the ribbon arch could be twisted as it was inserted into its slot.

Disadvantages: the major weakness of the appliance was that it provided relatively poor

control of root position. The resiliency of the ribbon archwire simply did not allow generation of

the moments necessary to torque roots to a new position.

4. Edgewise appliance: To overcome the deficiencies of the ribbon arch, Angle reoriented the slot from vertical to

horizontal and inserted a rectangular wire rotated 90 degrees to the orientation it had with the ribbon arch.

The dimensions of the slot were altered to 22 x 28 mils, and a 22 x 28 precious metal wire was used. These dimensions, arrived at after extensive experimentation, did allow excellent control of crown and root position in all three planes of space.

After its introduction in 1928, this appliance became the mainstay of multibanded fixed appliance therapy, although the ribbon arch continued in common use for another decade.

Disadvantages: Heavy forces required

complex wire bending. Increased friction Extraoral forces for

anchorage required.

Charles tweedAngle gave orthodontics the edgewise bracket, but Tweed gave the specialty the appliance. Because of Charles Tweed’s skill and determination, the edgewise appliance became universally popular.Tweed’s many contributions to the specialty established a benchmark in orthodontic thought and treatment.Most notable among his many contributions were the following:1. He emphasized the four objectives of orthodontic treatment—aesthetics, health, function, and stability-with emphasis and concern for balance and harmony of the lower face.2. He developed the concept of positioning teeth over basal bone with emphasis on the mandibular incisors.3. He made the extraction of teeth for orthodontic correction acceptable. Tweed moved the teeth bodily and used the subdivision approach for anchorage control, first sliding the canines distally along the arch wire, then retracting the incisors.4. He enhanced the clinical application of cephalometrics.5. He developed the diagnostic facial triangle to make cephalometrics a diagnostic tool and a guide in treatment and in the evaluation of treatment results.6. He developed a concept of orderly treatment procedures and introduced anchorage preparation as a major step in treatment.7. He developed a fundamentally sound and consistent preorthodontic guidance program that popularizied serial extraction of primary and, later, permanent teeth.

Tweed-Merrifield Edgewise Appliance The neutral 0.022 slot edgewise appliance consists of posterior bands and anterior

mesh pads with single, double-width 0.022 brackets on the six anterior teeth; intermediate single width brackets on premolar bands; twin brackets on first molar bands; and heavy edgewise 0.022 tubes with mesial hooks on second molar bands

All bands have lingual cleats attached. Lingual cleats increase versatility and are especially necessary to correct and control rotations. Each of the brackets and tubes is placed at a right angle to the long axis of the tooth.

The brackets are positioned precisely in relation to the incisal edges of the incisor teeth and the cusps of the remaining teeth. No tip, torque, or variations in thickness are present in the bracket. A slot size of 0.022 allows the clinician to use a multiplicity of archwire dimensions.

The auxiliaries routinely used with the Tweed-Merrifield edgewise force system are elastics and directionally oriented headgear, primarily the high-pull J-hook headgear

and the straight-pull J-hook headgear. Patient compliance is imperative.

Begg ApplianceRaymond Begg had been taught use of the ribbon arch appliance at the Angle school before his return to Australia in the 1920s. Working independently in Adelaide, Begg also concluded that extraction of teeth was often necessary and set out to adapt the ribbon arch appliance so that it could be used for better control of root position. Begg's adaptation took three forms : (1) he replaced the precious metal ribbon arch with high-

strength 16mil stain lesss teel wire as this became available in the late 1930s;( 2) he retained the original ribbon arch bracket, but turned it upside down so that the bracket slot pointed gingivally rather than occlusally ,and (3) he added auxiliary springs to the appliance for control of root position.

In the resulting Begg appliance friction was minimized because the area of contact betweent he narrow ribbon arch bracket and the archwire was very small and the force of the wire against the bracket was also small.

Begg's strategy for anchorage control was tipping/ uprighting. It is a complete appliance in the sense that it allows good control of crown and

root position in all three planes of space.

STRAIGHT WIRE APPLIANCE The most revolutionary advancement in orthodontics within the past 50

years has been Lawrence F. Andrews’ development of the StraightWire Appliance (SWA) in 1970

This pre adjusted appliance soon became the standard of the specialty The SWA was based on measurements of 120 non orthodontic normal

cases, from which Andrews described the “Six Keys to Normal Occlusion.”

From his extensive measurements, Andrews determined the average tip and torque angles and in/out dimensions of the labial surface of each tooth relative to a flat labial arch wire plane, coined the “Andrews’ Plane”

He designed individual brackets for each tooth type to work without wire bending, because he found that when in optimal occlusion, there exists extensive similarities in morphology and position of normal tooth types

When each pre adjusted bracket was precisely positioned at the midpoint of each tooth’s facial axis, the brackets formed the Straight-Wire Appliance

He also developed a series of extraction brackets which include anti-tip and anti rotation components not found in the Standard SWA prescription.

STRAIGHT WIRE APPLIANCE contd

Disadvantages:Difficulties were encountered with treatment mechanics in the early years, clue to the heavy forces and possibly due to the increased tip in the anterior brackets. Consequently, deepening of the anterior bite, with creation of a lateral open bite, was seen in many cases, and this became known as the 'roller coaster' effect.

TIP EDGE BRACKETS : Peter C. Kesling developed the Tip-Edge bracket (trademarked by TP

Orthodontics) in 1986, by removing opposite corners of the edgewise bracket, to allow mesial and distal crown tipping during initial stages and engagement of rectangular wires for torque control during finishing stages

The effective Tip-Edge slot increases with tipping, while the conventional edgewise slot size decreases.

The bracket also features lateral wings for rotational control, and tie wing notches and a vertical slot for use with auxiliaries 

Preadjusted in 3 dimensions-tip,torque,in & out built in Slot size-0.022”x0.028

Modification of Angle's edgewise archwire slot into a Tip-Edge slot (a)Original slot with parallel opposed upper and lower surfaces.(b)Removal of diagonally opposed corners to permit free crown-tipping in

one direction only.(c) Addition of lateral wings for increased rotational control plus tie wing

notches and vertical slot for auxiliaries.

OTHERS □ Use of Andrews’ prescription throughout the specialty has shown that ideal tooth positions are sometimes not achieved with straight wires alone, and therefore numerous additional prescriptions have been developed by others, including Ronald Roth (1979), Ricketts, Alexander (1978 ), Hilgers, Burstone, Root/Tweed, Cetlin, Bench, Creekmore, Hasund, Orthos, and McLaughlin/Bennett (1997 – 2001 ) / Trevisi .

MBT SYSTEMHaving established an overall approach and a successful system of treatment mechanics using the preadjusted bracket system in its standard form, McLaughlin and Bennett then worked with Trevisi to re-design the entire bracket system to complement their proven treatment philosophy and to overcome the perceived inadequacies of the original SWA. They re-examined Andrews' original findings, and took into account additional research input from Japanese sourceswhen designing the MBT™ bracket system between 1993 and 1997.

The MBT Bracket System MBT bracket system is a third-generation bracket system retained all that was best in the

original design, but at the same time introduced a range of improvements and specification changes to overcome the clinical shortcomings.

Its design was based on a balance of basic science and many years of clinical experience. MBT'“ is a version of the preadjusted bracket system specifically for use with light, continuous

forces, lacebacks and bendbacks, and it was designed to work ideally with sliding mechanics. The original system of dots and dashes was superseded by laser numbering of standard size

metal brackets, and the rectangular shape was replaced by the rhomboidal form. This reduced the bulk of each bracket and coordinated perspective lines through only two planes, thereby assisting accuracy of bracket placement.

The bracket system was made available in standard metal, mid-sized, and clear forms It had sufficient versatility to deal with most clinical situations, and to limit inventory levels.

Topic related written question in previous exam:

Ques – july 2014, 3-a,What are the different fixed orthodontic techniques? 3-b, Mention the difference between standard edgewise and straight wire technique.

Ques- jan-2013, 4-a Evolution of bracket system in orthodontic treatment.

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