Fixed orthodontic appliance/ for orthodontists by Almuzian

UNIVERSITY OF GLASGOW
Fixed appliances
Personal notes
Dr. Mohammed Al-Muzian
1/1/2013
.

Mohammed Almuzian. University of Glasgow, 2013 Page 1
FIXED APPLIANCE
History
1. E arch appliance (Angle)
2. Pin and tube appliance (Angle)
3. Ribbon arch appliance (Angle)
4. Standard Edgewise appliance (Angle 1920`s)
5. Modified standard Edgewise appliance (using rotational arm or Lewis arm, using different
slot size)
6. Labiolingual twin wire appliances
7. Begg appliance (Begg 1950`s) he turn the ribbon arch upside down so it pointed
gingivally rather than occlusally, used stiff SS wire, intermaxillary elastic and use
auxiliaries and advocate extraction.
8. Pre-adjusted Edgewise appliance (Straight Wire – Andrews 1970`s)
9. Lingual appliance (Kurz 1970`s)
10. Tip Edge appliance (Kesling 1988)
Comparison of fixed and removable appliances
NB: Note that the headgear tube may be placed gingivally (closer to the centre of
resistance of the tooth) or occlusally (less gingival impingement and easier for patient to
see for fitting headgear

General classification of the FA
Andrews defines four basic appliance types:
1. Non-programmed appliances: A non-programmed appliance is a set of brackets that are
the same for all tooth types and which rely totally on wire bending to obtain optimal tooth
position.
2. Partially programmed appliances: Partially programmed appliances are sets of brackets
designed with some built-in features but which always require some wire bending. These
appliances by definition lack at least one slot-siting feature.
3. Fully programmed appliances: Fully programmed appliances are a set of brackets
designed to guide teeth directly to their goal positions with unbent archwires. The generic
term is pre-adjusted edgewise appliances.
4. Semi-custom appliances: The term semi-custom appliances is used to describe the
variations from standard Straight-Wire technique, such as inverting brackets or mixing of
brackets from different prescriptions in order to produce specific tooth movements to an
individual patient's needs.
5. Custom appliances: Custom appliances are a set of brackets designed to match precisely
the unique morphology and guidance needs of a specific patient eg. Insignia
Classification of bracket designs
 Single wing
 Siamese
 Mini bracket
 Self-ligation
 Tip edge
The standard edgewise appliance
 The standard edgewise appliance originated from the work of Edward Angle (Angle,
1928).
 The standard edgewise appliance became the fixed appliance of choice up until the late
1970s
 But it did suffer from several disadvantages.

1. In particular, the non-programmed bracket slot meant that final detailing of tooth position
in rectangular wires was dependent upon many bends being placed within the archwire for
each individual tooth
2. The presence of these bends also meant that space closure had to be carried out with
closing loops, which were also complicated to bend
3. In addition, teeth are moved bodily along the archwire through alveolar bone using an
edgewise appliance, which is demanding upon anchorage.
Light wire appliances (Begg appliance design)
1. In an effort to overcome the high anchorage demand associated with the standard
edgewise appliance, an Australian orthodontist, P. Raymond Begg developed a fixed
appliance system where tooth movement was based around the concept of differential
force (Begg, 1956):
• The tooth crowns are initially tipped into their desired position using intermaxillary
elastics;
• The roots are then uprighted as a separate procedure using auxiliary springs.
2. It is much easier to tip a tooth than move it bodily and this requires less force, so the Begg
technique was much lighter on anchorage and became very popular during the 1960s and
1970s .
Begg appliance design
 The original light wire appliance was the Begg appliance, which utilized a simple bracket
that was identical for each tooth.
 Begg brackets incorporate a narrow open-ended slot, into which a stiff round archwire is
placed from the gingival aspect and held in position by the insertion of a small metallic
auxiliary lock pin
 The loosely fitting round wire allows considerable scope for the teeth to tip under the
influence of light intermaxillary elastic traction, which in combination with anchor bends
placed in rigid archwires, allows rapid reduction of both overbite and overjet during initial
treatment.
 Following this, a variety of auxiliary springs is required to upright and torques the teeth
into the correct position.

Tip-Edge appliance
 Because Begg appliance only uses round archwires, precise finishing is difficult and the
use of auxiliaries in the final stages of treatment to upright teeth that often have been
tipped through quite significant distances proved to be quite complex, difficult to control
and also time-consuming.
 In an effort to address this, the Tip-Edge appliance was developed by Peter Kesling in the
late 1980s (Kesling, 1988; Kesling et al, 1991).
 This appliance also tips the teeth during the initial phase of treatment, but allows later
uprighting with more rigid three-dimensional control by closing the slot down around
full-size rectangular archwires
 Tip edge appliance, same prescription of Roth except
 L incisor increased tip
 Canine less torque
 Premolar tip and torque midway bet Roth and Andrews
 Molar : upper as Andrews and lower with reduced torque
More recently, the Tip-Edge PLUS bracket has been introduced, which eliminates the
need for auxiliary springs by incorporating a tunnel deep to the main bracket slot. A
superelastic auxiliary archwire placed into this tunnel during the final stages of treatment
provides the uprighting forces necessary for the bracket prescription to be expressed
(Parkhouse, 2007).
Self-ligating brackets
The concept is not new, having been originally pioneered in the 1930s. However, these
bracket systems have undergone a renaissance over the past two decades, largely because
of enhanced ingenuity and reliability.
Lingual bracket
1. Developed in 1975 by Kruz USA and Fujita Japan
2. It is mainly fully programmed appliance (means that all SWT feature are
involved) and either semi or fully customized to the patient.

Straight wire appliances (SWA)
The Straight-Wire Appliance was originally developed by Larry Andrews in 1976 and is a
fully preadjusted edgewise appliance based on Andrews' six keys to occlusion (Andrews
1972).
Some terminology in SWA
1. Bracket base: the most lingual portion of the bracket stem
2. Slot Base: the lingual wall of the slot.
3. Slot point the centerline of the slot. It is equidistant from the gingival and occlusal slot
walls and is centered mesiodistally.
4. Slot axis: the line connect slot and base point
5. Bracket Stem: the portion of a bracket between the bracket base and the slot base.
6. Base Point: it is a point on the bracket base at the extension of the slot axis.
Features of SWA as describe by Andrews
1. Primary design features LIKE vertical and horizontal countered bracket, torque in base,
tip in bracket, in and out offset
2. Siting features: these are design features which site the bracket slot in a correct position
(i.e. slot base coincident with FA while the bracket base contoured with the tooth surface
when the clinician correctly positions the bracket vertically and horizontally.
3. Auxiliary features: these contribute to the biologic aspects of treatment but are not
involved with siting the slot. e.g.: power arms, facebow tubes, auxiliary tubes, parallel tie
wings, rotation wings
4. Convenience features: convenience features are not involved in siting the slot or
contributing to the biologic aspects of treatment but which make the appliance easier to
use or more comfortable to the patient. e.g.: extended gingival tie wings, facial contouring
of brackets, bracket identification, bracket material.
Advantages
Roth, 1976
1. Ease of arch wire construction and placement.
2. Cleanliness and patient comfort due to absence of the wire bending

3. Better rotation control: Since there are no bends in the arch wire, an inter-bracket span
of any great magnitude is unnecessary to reduce the force level; therefore, wide Siamese
brackets can be employed to control rotations.
4. Less "round-tripping." Since the teeth move in more direct vector lines from their
maloccluded positions to their individualized positions, there is less "round-tripping" of
the teeth.
5. Better control of tooth positions and finishing. Thus there is a more consistent result
with shorter treatment time.
6. Complete space closure in both extraction and non-extraction cases can be accomplished
with one set of arch wires since there are no bends in the arch wires to interfere with the
brackets themselves during space closure.
7. Bracket Identification. As follow:
 Upper central incisors black
 Upper lateral incisors pink
 Upper canine green
 Upper premolars purple
 Lower central and lateral incisors yellow
 Lower canine blue
 Lower first premolar black
 Lower second premolar white
Disadvantages
1. Friction
2. Perceived anchorage demands
3. Technical, biological and mechanical variability still requires adjustments in the
appliance to accommodate this. Greekmore, 1993 described some reasons why current
preadjusted orthodontic appliances do not achieve ideal tooth positions with the use of
"straight" wires.
A. The most frequent reason is inaccurate bracket placement. Solution: indirect positioning.
B. Variations in the malocclusion require variations in the positions of maxillary and
mandibular incisors. Solution: use customized bracket, cephalogram analysis to determine
the prescription needed.

C. Variations in tooth structure, such as irregular facial surfaces, crown-root angulations.
Solution: use customized bracket.
D. Edgewise orthodontic appliances have some significant mechanical deficiencies:
 Force application to teeth through brackets located away from the center of resistance,(use
lingual bracket or exaggerated prescription)
 Play between the arch wire and the arch wire slot (slop).
The reason for the slop
1. The amount of the play between slot and wire.
2. Lack of stiffness in the AW
3. Lack of stiffness in the bracket slot as in acrylic bracket
4. Incomplete ligation
5. Oversized slot and undersized wire
Bracket positioning
1. Individualized bracket positioning
2. Standardized method
3. FACC
4. Progressive positioning by Pitts
5. Mid-point of the crown
In details
1. Standardized method: With the original edgewise appliance, bracket placement was
normally carried out using standard millimeter measurements using a gauge from the
incisal or occlusal edge of each tooth, irrespective of tooth size. The brackets were
positioned at different curvature on the teeth, and this in turn led to variations in the
amount of torque and in-out produced by the brackets. However, because archwire
bending was needed in any case, this system was acceptable with the edgewise appliance.
2. FACC: Andrews introduced the concept of the FACC. The FACC (facial axis of the
clinical crown) is for all teeth except for molars, the most prominent portion of the central
lobe on each crown's facial surface. On molars, the FACC is represented by the buccal
groove that separates the two mesial buccal cusps. The FA (facial axis) point is the
midpoint of the FACC. However, as described below, it proved difficult to obtain
accurate vertical positioning using only the middle of the clinical crown.

3. Individualized bracket positioning (Thicket 2007)
 Variation in occlusal-gingival positioning with more gingivally in AOB and occlusally in
deep bite case.
 Variation in torque application:
 Variation in MD positioning
 Variation in angulation: Where teeth have to be translated a significant distance (such as
in pseudo transposition cases) there is an increased tendency to tip and so the brackets
should be angulated to prevent this; this often requires a significant overangulation of the
bracket. A similar situation occurs where implants are to be placed post orthodontic
treatment and the tooth roots must be parallel to one another to leave room for the
implant.
4. Progressive positioning by Pitts: A more modern take on bracket positioning is given by
Pitts (2009). Pitts places brackets more gingival (posterior-anterior progressive
positioning) than normal and using the mesiodistal contact points of the teeth as a
reference line (the M-D contact line)
5. Mid-point of the crown: McLaughlin and Bennett advocate the use individualized
bracket-positioning charts. From this data, a placement chart was devised from which the
user selects the row of bracket heights which most closely corresponds to the half clinical
crown height of the dentition to be bonded.
McLaughlin and Bennett determined ideal bracket placement positions based on the
midpoint of the clinical crown using data on:
1. anatomical crown heights
2. clinical crown heights
3. American Boards or Angle Society cases
4. debonded cases that had settled into a good six keys occlusion
They found minor deviations of the centres of the clinical crowns on the:
1. upper premolars
2. the upper second molars
3. lower canines
4. lower first molars

Exceptions to full bracket placement
1. Cases with unerupted teeth, or teeth significantly out of the arch form
2. Deep-bite cases in which the upper incisors interfere with bracket placement on the lower
incisors, the upper incisors can be bracketed and the lower incisors left unbracketed at the
start of treatment or a biteplate can be placed at the initial bonding visit, provided the
occlusion allows this.
3. Deep bite with distally inclined canine
Creating the bite-plate effect to allow full placement of the bracket
There are four methods of creating the bite-plate effect:
1. Appliances can be placed on the upper arch only, which allows for proclination of the
upper incisors. This frees the lower incisors for placement of brackets. This technique is
helpful in high-angle cases, because posterior extrusion is minimized.
2. Acrylic removable anterior bite plates can be placed. The disadvantage of these removable
appliances is that they are not always worn by the patient. Also, tooth movements lead to
improper fit of these appliances after a relatively short period of time. Lastly it should be
used in growing patient unless clockwise rotation of the mandible is required.
3. An adequate substitute for a removable bite plate in low angle deep-bite cases is the
placement of direct bonding material on the palatal surface of the upper incisors . Colored
adhesives such as BandlockIM from Reliance or Transbond Plus™ from 3M Unitek are
useful and can be easily removed from the tooth surfaces after bite opening. Sometime the
use of ready-made metal or plastic bite turbo can be used.

4. In average- to high-angle cases, the placement of similar colored adhesives on the occlusal
surface of the first molars is helpful in bite opening. This adhesive can be progressively
removed as the bite opens.
Horizontal accuracy during bracket positioning
1. It not significantly affect incisors because of their flat surface but it affect canine and
premolar.
2. It is better to be checked by mirror
3. In lower canine it is better to positioned it more mesially to ensure good contact with lower
incisors.
4. In rotated teeth better to position it more toward the rotated surface
Axial accuracy during bracket positioning
The bracket wings need to be parallel to the long axis
Vertical accuracy during bracket positioning
Accuracy is greatly improved by the use of gauges and an individualized bracket-positioning
chart. This will deal with difficulties such as
 Tooth length discrepancies,
 Fracture tooth
 Labially and lingually displaced roots,
 Partly erupted teeth,
 Gingival hyperplasia
Variation in positioning during bracket placement
1. In non-extraction cases the bracket positioned at the middle of crown at LA point but in
extraction cases it should be more 1mm gingival to increase torque expression which if
incorrect might cause some marginal discrepancies between 3 and 5.
2. Fractured or worn incisal edges (or cusp tips) should be restored, in the orthodontist's
mind's eye, prior to bonding or banding, rather than position the attachments too
gingivally and extrude the teeth. Failure to do so leads to incorrect height of gingival
margins, cingulae and marginal ridges. It is recommended that the first incisor bracket
placed in each arch should be on the tooth with the most natural shape and crown height.

The brackets on the other teeth can then be adjusted to the same distance from the incisal
edge, regardless of their gingival contours
3. Premolars: As a general rule, inexperienced orthodontists tend to place the buccal
segment brackets too occlusally, particularly in the lower arch. This results in infra
occlusion, incorrect torque and, for the lower arch, the increased likelihood of the
brackets being bitten off.
4. Molars:
 It is important for a similar amount of mesial and distal buccal cusps to be visible above
the band to ensure a correct mesio-distal angulation.
 It is preferable to show more mesial cusp than distal cusp, particularly where premolar
extraction therapy is involved.
 It is also necessary to ensure appropriate seating of the band on the palatal and lingual
sides in order not to prejudice the torque expression.
 The banding of second molars also deserves particular attention. As a general rule, it is
desirable for the tubes on the second molars to be 2 mm to l mm more occlusal than on
the first molar in order to prevent the second molars from taking the majority of the forces
of occlusion. This is particularly important in high angle cases where banding the upper
second molars is mandatory to ensure that the palatal cusps do not hang low and cause
interference.
5. Local bracket variations
A. Canine in lateral incisor positions
 Some clinicians advocate bonding lateral incisor brackets on these canines
 The preferred option is to fit Andrews canine brackets upside down.
 The same effect can be achieved by bonding an inverted premolar bracket, either Roth,
Andrews or MBT.
B. Palatal laterals
 The use of full thickness archwires.
 Torque auxiliary
 Making third order wire adjustments for individual root torque.
 A more elegant solution is to fit an Andrews lateral incisor bracket upside down.
C. Lower canines angulation in Class III cases
1. The answer is to bond contra lateral brackets (i.e. 13 bracket bonded on 31 and vice
versa).

2. Not only does the adaptation enable dento-alveolar compensation, it also reduces the
anchorage requirements
D. Second premolar extraction
A relatively common observation where 515 have been extracted is for inadequate root
paralleling with excessive apical separation between the first premolars and molars at the
end of treatment. This problem can be dealt with by applying a combination of measures.
 The use of a Roth molar tube is helpful,
 Mesial tipping being further reduced by ensuring the molar band is well seated mesially.
 Banding second molars and keeping the appliance in place for several weeks following
space closure are also advisable.
 The premolar bracket can be bonded at a slight angle to ensure full apical correction
during space closure.
E. Risk of unwanted lower incisor proclination
The use of lower incisor brackets with -6° torque (lingual crown torque) is equivalent to
introducing 5° torque in the archwire.
F. First molars in Class II occlusion after extraction of two maxillary premolars
 The great majority of cases are treated to a Class I molar relationship but, occasionally,
the aim is to achieve a Class II molar inter-digitation. The accepted good molar position
with a slight mesial angulation and disto-palatal rotation is inappropriate in a Class II
occlusion.
 The Andrews prescription which has 5° mesial angulation is particularly inappropriate as
these results in the mesial marginal ridge being totally out of occlusion. The relevance of
rotation is that, in a Class II occlusion, the upper molar mesio-buccal cusp needs to be
tucked in between the lower second premolar and first molar, and the disto-buccal cusp
needs to be more buccal to avoid an edge to edge occlusion with the lower molar.
 What is required is a tube prescription which has 0° mesio-distal angulation, 0° rotation
but maintains 14° buccal root torque. Tubes with a 0, 0, 14 prescription are available in
either triple or single configuration. It is recommended these should be stocked in small
numbers for direct bonding or welding onto plain bands in order to avoid the high cost of
pre-welded stock. Incidentally, this prescription is also highly suitable for many
orthognathic cases.

 Other option includes swapping the contralateral second molar MBT tubes and uses it on
the first molars.
Bracket bonding
Bracket bonding can be achieved in two ways:
1. Direct bonding places the brackets on the teeth individually at the chairside;
2. Indirect bonding places the brackets on study models in the laboratory and these are
transferred to the teeth using a positioning tray. The advantage is greater accuracy of
bracket positioning; however, the extra cost and time involved make this process less
popular for routine orthodontics with labial appliances, although it is used when placing
lingual fixed appliances. Orthodontic brackets are generally bonded to enamel using
mechanical locking created by acid-etching the enamel surface of the teeth.
Indirect bonding (Thomas 1979)
ADVANTAGES OF INDIRECT BONDING
1. Accurate bracket placement
2. Optimizing the use of doctor’s time
3. Avoiding band fitting on posterior teeth
4. Eliminating the need for separators
5. Improved ability to bond posterior teeth
6. Improved patient comfort and hygiene
DISADVANTAGES OF INDIRECT BONDING
1. Technique sensitive
2. Additional set of impressions needed
3. Posterior attachments more likely to fail if patient chews ice, etc.
SAW prescriptions features
The most common prescriptions used seem to be:

1. Andrews,
2. Roth
3. MBT.
For all prescriptions, the prominence values (in-out first order bend) are the same and so
the only variables within a prescription are:
1. Angulation
2. Inclination
3. Offset (counter-rotation)
4. Offset gingival pad brackets
In details
Prominence
Prominence or in/out or first order correction: it is an adjustment built into the bracket
base to compensate for the differing buccolingual thickness of teeth.
Angulation
Angulation or tip is built into brackets to ensure that teeth are placed at a specified
mesiodistal angulation. Tip is built into brackets in the Straight-Wire Appliance by cutting
the slot at an angle to the vertical axis of the bracket and not by rotating the bracket base
in relation to bracket stem. This ensures that the bracket sits squarely on the surface of the
tooth.
Inclination
Inclination or torque. It may be placed in a preadjusted bracket by putting the torque in
the face or in its base of the bracket.
1. Torque in the face is achieved by cutting the slot at an angle to the face of the bracket. For
this type of bracket, the slot axis will not be
coincident with the base point. As the slot point may
be used instead of the base point to position the
bracket, then the vertical discrepancies between these
points will become greater as increasing torque is put
into the bracket. Brackets with torque in the face will

therefore have vertical positioning errors due to the discrepancy between the slot point
and base point in these brackets and the fact that the base point cannot lie on the slot axis
unless there is zero torque in the bracket. These vertical positioning errors will in turn
affect the expression of in/out & torque built into the bracket. The magnitude of these
vertical errors is dependent on the amount of torque built into the bracket but does not
exceed 0.7 mm in the lower arch or 0.5 mm in the upper arch in either the Andrews or
Roth prescriptions. However the vertical positioning errors of this magnitude are unlikely
to be clinically significant.
2. Torque in the base of the bracket is built-in by adjusting the size of the triangle of metal in
the base of the bracket (base stem). Until comparatively recently this was a patented
feature of the Straight-Wire Appliance in the USA but not in Europe. Torque in the base
ensures that the base point and the slot point are coincident.
Choice of the torque prescription
It depends on
1. Population sample
2. Where the bracket position is aimed by the inventor
3. Type of malocclusion
4. Mechanics of treatment
5. Treatment plan: Exo or non exo
6. Amount of the play between the slot and the wire which is known by the company
Offset (counter-rotation)
 Offset (also known as counter-rotation in translation series brackets) is built into upper
buccal tube assemblies, premolar, canine, incisor brackets and lower molar tubes in
translation series prescriptions to counteract the tendency of teeth to tip into the extraction
space during space closure.
 This rotational correction tends to rotate teeth mesially anterior to the extraction site and
distally distal to it.
Offset gingival pad brackets
These brackets were originally described by Swartz in 1994. Bonding premolars is
traditionally difficult because:
1. The short clinical crown

2. Enamel abnormalities in the gingival third with more aprismatic enamel at this region. At
this region, the enamel rod direction that is more divergent from perpendicular and thus
less retentive of resin tags
3. Improve bond strength by increasing the pad size by utilizing more of the coronal enamel
for retention and less dislodgement because the opposing teeth are away from contacting
the bracket wings
4. Reduce gingival impingement.
5. Correct positioning of the slot in relation to FA.
6. Easier to place
7. Easier ligation
However, an RCT had been carried out by Tidy and Coley-Smith (1998) which shows
that gingival offset brackets have a risk of bond failure which is five times more than with
conventional brackets. This corresponds to the more anecdotal improvement suggested by
Swartz (1994). Also, Thrend 2004 show more bond failure in offset bracket
Slot Height and depth
Edgewise brackets have rectangular slots, which are deeper in the horizontal as opposed
to vertical plane. Slot and archwire dimensions have traditionally been described
empirically, with the original dimensions being 0.022 inches vertically and 0.028 inches
horizontally to accommodate gold archwires, which were quite soft. Once stiffer stainless
steel archwires were introduced, slot size was reduced to 0.018 inches vertically and
0.025 inches horizontally. However, with greater uptake of preadjusted edgewise systems,
there has been a move back to the original slot dimension.
Advantage of 022 over 018 slot
1. It gives lighter forces in the early stages of treatment by providing more slop in the
early stages of treatment
2. Better control of tipping during sliding
3. Better control of rotation during sliding
4. Better expression of torque
5. Better control of OB
6. Better control of arch width
7. Better stabilization of segment after orthognathic surgery
8. Multiple wire size selection

Disadvantage of 022
1. High friction
2. Multiple wire sequence until the working AW is reached
3. Root resorption
4. Full size wire in the finishing cause Heavy force (normal torque force 60g per tooth), to
overcome this:
 Use undersize wire with added torque
 Use flexible materials
 Use super torque bracket with under size wire
 Use torque auxillary
NB:
 A study by Cash et al 2004, found that most of the bracket slot are height oversized and
the wire are height undersized.
 Depth of the bracket are 028 except in Damon are 027 at LLS to provide more rotational
control
Types of SWA
Andrews prescriptions
Incisor bracket sets
Andrews (1989) described different incisor bracket sets for use in different skeletal
patterns:
1. The Set A bracket set, designed for Class 2 skeletal patterns more less palatal root torque
in the upper incisors to facilitate the establishment of a normal incisor relationship
whereas
2. Set C for Class 3 skeletal patterns had the reverse.
3. Set S was for Class 1 malocclusions.
Translation (extraction) series brackets
Translation brackets were introduced by Andrews (1989) to compensate for the unwanted
tooth movements that occurred during closure of extraction spaces. These posterior

bracket sets (i.e.: molars, premolars and canines) had increased tip and antirotation
according to how much translation of the tooth was expected.
1. Minimum 0-2mm (T1)
2. moderate 3-4 (T2)
3. Maximum 5mm (T3) bracket sets are available.
4. T4 brackets are molar brackets without the five degrees of tip in the standard prescription.
Harradine and Birnie (2001), however, feel that there is not enough torque in the upper
labial segment in the Andrews prescription.
The mesial angulation built into the Andrews tube is the result of the observed angulation
of the first molars in his sample of 120 adults with ideal occlusion. However, the use of
this prescription is inappropriate clinically for the following reasons:
1. At the completion of treatment, at the age of approximately 14, the facial complex is still
growing downwards and forwards. Molar crowns left upright at this age will assume the
mesial angulation found in the adult ideal dentition by the time the patient ceases
growing. But leaving a patient with mesially angulated upper first molars at the age of 14
may result in over-angulation by the time growth is complete.
2. Treating a malocclusion to a mesially angulated upper molar position is more anchorage
demanding as the roots of the upper molars have to be moved more distally.
3. Treatment based on headgear with Andrews’s tubes is more liable to cause iatrogenic root
resorption of first molars against unerupted second molars.
Roth prescriptions
The objectives of Roth in his treatment are
1. Pleasant aesthetic
2. Stability of treatment depends of good functional occlusion.
3. TMJ problem less in good occlusion
For these reasons the prescriptions are:
1. More torque in the upper incisors than Andrews one because it is an extraction series
bracket.
2. The upper canines have additional tip and less torque while lower canine has increased tip
than in the standard prescription which facilitates canine guidance as a fundamental for
functional occlusion.

3. The Roth prescription gives more torque in the upper molars to prevent dropping of the
palatal cusps.
4. Since the prescription is extraction based, there is anti-tip and anti-rotation built into the
buccal segment brackets.
5. Lower incisor bracket are set C series bracket
MBTVERSATILE +
The Bennett-McLaughlin prescription follows the Andrews prescription closely. MBT™
treatment philosophy is:
A. Bracket design
1. Mid-size metal brackets
2. Rhomboidal shape,
3. Torque in base
4. The .022 not the .018 slot
5. Thicker 0.5mm bracket on upper second premolar if they r small
B. Light continuous forces
C. Anchorage control early in treatment. This achieved by
1. Light force
2. Reduced tip
3. Bendback
4. Laceback
D. Bracket positioning chart
E. Archwire hooks
F. Enmas space closure
G. Aspects of versatility
 For upper set of bracket
1. Options for palatally displaced upper lateral incisors (-10°).
2. Three torque options for the upper canines (-7° , 0° , and +7°).
3. Interchangeable upper premolar brackets - the same tip and torque.
4. Use of upper second molar tubes on first molars when HG not used.
5. Three torque options for lower canines (-6° , 0", and +6").
6. Bondable mini second molar tubes for partially erupted teeth
7. Different upper 5 bracket thickness

 For lower set of bracket
1. Interchangeable lower incisor brackets - the same tip and torque.
2. Use of lower second molar tubes for the upper first and second molars of the opposite side,
when finishing cases to a Class II molar relationship. Also the tube is placed at a different tip
position, with more enamel from the mesial cusp visible than from the distal cusp. This
introduces the necessary tip adjustment.
3. Different lower 5 bracket thickness
4. Lower 5 tube which help to control sliding, avoid interference with upper, clean, easy and
quick
5. Lower first molar non-convertible tubes to reduce its thickness
6. Lower first molar double tube and upper first molar triple tube attachments
7. Bondable mini second molar tubes for partially erupted teeth
H. Bracket prescription
1. Increased maxillary incisors labial crown torque
a. For class II D I:
 It may be help in expressing the palatal root torque in undersized wire
 It helps to counteract the side effect of functional appliance
 It helps to counteract the side effect of class II elastic
 help in the reduction of OB by proclining the ULS.
 It helps to counteract the effect of retroclination during space closure
 But the wagon wheel effect will be expressed due to increase in the torque which will result
in reduction of the expression of the mesial tip of ULS and this will reduce the anchorage
demands. For each 4 degree increase in the torque there is 1 degree reduction in the mesial
tip.
b. For class II D2, same as class II D1
c. for class III it help to express the camouflaging effect of ULS
2. Increased lingual crown torque of LLS
a. For class II D I and class II D2
 It helps to counteract the side effect of class II elastic by preventing the LLS proclination
 It helps to counteract the side effect of functional appliance

 it helps to counteract the effect of RCOS during deep OB correction or when using utility
arch
b. For class III it help to express the camouflaging effect of LLS
3. Increased buccal root torque
 Counteract the tipping of expansion by expander or functional in class 2 and class3
 Increase anchorage by cortical bone theory
 Better intercuspation
4. Reduced lingual root torque of lower posterior teeth
 Provide better intercuspation
 Counteract the rolling effect of class II elastic or during space closure in the lower arch
 It reduce the chance of gum recession
5. Upper molar offset at 10 degree
 counteract the unwanted rotational movement during space closure in the upper arch and this
might strengthen the anchorage
 Aid in class I Andrews molar relationship
6. Zero degree tip of upper molars
 This is called effective tip, because when we place the tube, it is parallel to the occlusal
surface which already tipped 5 degree forward. the same applied for lower molars
 Provide better intercuspation
 To keep the molar upright while the future growth might cause further mesial tip. This is
because the MBT mainly used in growing patients.
 Also this might reduce the anchorage demand
 Prevent distal tipping of the root of the first molar against second molars which might cause
further root resorption when HG is used
7. Reduced canine tip compared to Roth
 To reduce the anchorage demand
 There is a variety of canine tip prescription and uses according to the clinical scenarios as
follow:
A. Arch form: in narrow arch use +7 to avoid dehiscence

B. Canine labio-palatal position: in buccaly positioned canine, better to used +7 to avoid
dehiscence
C. Extraction: if the canine wanted to be retracted distally, use +7 to make the root in the
middle of the canceller’s bone
D. Expansion: use -7 in the upper
E. Missing lateral: use +7 in upper
Why MBTless anchorage demand
1. Light force
2. The wagon wheel effect: because increasing the torque will cause the mesial tip of ULS to be
reduced and this will reduce the anchorage demands
3. Reduced canine, premolar and molar tip compared to Roth
4. Increased molar root torque buccally, increase anchorage by cortical bone theory
5. Upper molar 10 degree offset, counteract the unwanted rotational movement during space
closure in the upper arch and this might strengthen the anchorage
Damon system
The Damon prescription is similar to the Andrews prescription but with less tip on the
canines and the option of increased upper incisor torque and the class 3 lower incisor set.
Comparison of bracket prescriptions
Maxillary
Prescription 1
Ti/To/Ro
2
Ti/To/Ro
3
Ti/To/Ro
4
Ti/To/Ro
5
Ti/To/Ro
6
Ti/To/Ro
7
Ti/To/Ro
Andrews 5/7/0 9/3/0 11/-7/0 2/-7/0 2/-7/0 0/-9/10 0/-9/10
Roth 5/12/0 9/8/0 13/-2/4 0/-7/2 0/-7/2 0/-14/14 0/-14/14

MBT 4/17/0 8/10/0 8/-7/0 0/-7/0 0/-7/0 0/-14/10 0/-14/10
Mandibular
Prescription 1
Ti/To/Ro
2
Ti/To/Ro
3
Ti/To/R
o
4
Ti/To/Ro
5
Ti/To/Ro
6
Ti/To/Ro
7
Ti/To/Ro
Andrews 2/-6/0 2/-6/0 5/-11/0 2/-17/0 2/-22/0 2/-30/0 2/-31/0
Roth 2/-1/0 2/-1/0 7/-11/2 -1/-17/4 0/-22/4 -1/-30/4 -1/-30/4
MBT 0/-6/0 0/-6/0 3/-6/0 2/-12/0 2/-17/0 0/-20/0 0/-10/0
Components of fixed appliances
1. Brackets and molar tubes
2. Archwires, which are attached to the brackets and pass through the molar tubes;
3. Auxiliaries, which will vary between appliance types, but include bracket ligatures, pins,
elastics, uprighting and torquing springs, ligature wires and fixed devices for anchorage
reinforcement or arch expansion.
Bracket materials
1. Metal (SS, CrCo,NiTi, gold)
2. Aesthetic brackets
 Transparent bracket
A. Ceramic
B. Polycarbonate(very weak and creep under force)
C. Polyurethane or reinforced polycarbonate
 Lingual bracket
In details

Stainless steel bracket
1. Stainless steel bracket (Iron 71, Nickle 8, Cr 18, carbon)
2. 10% of people in US have allergy to nickel however mucosal reaction is very
insignificant when patient has allergy and almost he can withstand it even if her skin is
allergic to nickel.
3. Construction:
Castable,
Milled,
Metal injection moulding
Titanium
1. Used in allergic pt to nickel. It is more wettable than SS so it bond better to
bonding materials.
2. Titanium: covered by layer of Ti to reduce friction
CrCo.
1. Less nickel sensitivity and less release of nickel
2. Harder than stainless steel.
3. More friction than stainless steel brackets.
Aesthetic and ceramic bracket
Polymer like
1. Polycarbonate
2. Polyurethrane
3. Metal reinforced polycarbonate or polyurethrane
The main problems encountered were
• Weak bond strength,
• Distortion of the bracket from the wires
• Fracture or wear of the bracket

Ceramic brackets
Types
4. Polycrystalline(opaque) eg Transcend
5. Monocrystalline(very hard and translucent) eg Saffire
6. Metal reinforced polycrystalline
7. Others eg Zirconia
8. Hybrid
1. Polycrystalline
• Aluminium silicate particles are mixed with a binder and injected into a mould.
• The mould is then heated to 1800 degrees C.
• Machined with diamond tools, ultrasound or lasers to prepare bracket slot.
Advantages
It can be moulded, therefore can be produced in large quantities and at a low cost.
Disadvantages
1. Structural imperfections
2. High friction.
3. Opaque.
4. Low fracture toughness.
2. Monocrystalline
1. Machined by milling synthetic Safire.
2. Aluminium oxide particles are melted (heated to over 2100 degrees C)
3. Then cooled slowly and then milled
Advantages
1. Less imperfections and impurities,.
2. Clear
3. Lower friction
Disadvantages
1. Expensive
2. Low toughness

Metal reinforced polycrystalline
The most successful ceramic bracket is the Clarity bracket which goes some way
towards addressing some of the problems by incorporating a metal slot to reduce friction
and a weakness in the base to allow easier debonding.
Zirconia
Similar properties to alumina (polycrystalline) brackets.
Problems with ceramic brackets,
Karamouzos, 1997, Bishara 2000
1. Bracket placement
2. Bracket ligation
3. Bracket fracture
4. Friction
5. Enamel wear
6. Bond strength and debonding
7. Cost
In details
Bracket placement
Problems:
1. Visual information is not as good.
2. Bracket markers help in bracket positioning but it might make the removal of the
excess bonding material more difficult.
Solutions:
1. Visualise from different angles.
2. Immediate clean up and coloured adhesives are helpful.
3. Using transfer gauge
4. Indirect bonding
Ligation
Problems:
1. Clear and tooth coloured elastic ligatures tend to discolour.

2. Metal ligatures are obvious under clear brackets.
3. Ligatures lockers can fracture the brackets.
Solutions:
1. Use opaque brackets (Clarity).
2. Use Teflon coated ligatures or 'white' elastomeric modules.
3. Use thin Quick Ligs, which must be fully tied in with the twisted tails tucked
under the archwires.
4. Self-ligating ceramic brackets (Damon clear)!!!!!!
Bracket fracture
1. Results from lack of ductility and low fracture toughness (Birnie 1990). eg tie
wings fracture or fracture of the brackets on debond.
2. Ceramic brackets are not recommended for
 Orthognathic patients,
 Small teeth,
 LLS,
 Deep OB.
 Use low profile bracket
Friction
Problems:
1. Relatively rough surface of the ceramic slot significantly increases frictional
resistance.
2. Hard ceramic abrades stainless steel wire.
Polycrystalline ceramic brackets are manufactured either by an injection moulding
process, which produces a smooth surface texture, or by milling or machining with
diamond tools, resulting in a rougher final surface texture.
Solutions
1. Perfecting the slot surface eg lined bracket slot or by using lower friction ceramics
eg zirconium oxide.
2. Use ceramic brackets with metal lined slots. Nishio et al. 2003 demonstrated
significantly higher frictional forces with ceramic brackets with metal slots compared to

stainless steel brackets. The difference is probably due to the difficulty in adapting the
metal sheath to the ceramic slot and due to their different expansion coefficients
3. Use closing loops rather than sliding mechanics.
4. Avoid bonding premolar teeth during space closure
5. Use metal premolar bracket.
6. Change arch wires each visit.
7. Consider the following
 Rectangular AWs > Round
 NiTi and TMA > Stainless steel
Enamel wear
Ceramic is 7 times harder than enamel. In vitro wear visible after only 15 chewing
cycles (less than one meal).
Solutions
1. May have to restrict use to upper arch only.
2. Must not bond teeth where there is an occlusal interference.
3. Use Glass ionomer cement to dis-occlude the teeth if the lower are bonded with
ceramic brackets.
4. Advance the upper incisors before bonding the lowers as in class II D2 cases.
5. Using polycarbonate bracket in case of deep overbite (Russell, 2005)
6. Rubber ligatures over tie wing slot can preventing contact of the opposing
dentition with the ceramic bracket, are a further method of reducing the risk of enamel
damage (Russell, 2005)
7. Use low profile bracket
Bond strength
It can be very strong with potential for enamel damage.
Solutions
I. Avoid the use of ceramic bracket in the following scenarios
1. Heavily restored teeth,
2. Non-vital ,
3. Perio involved
4. Lower incisors
5. Thin labial enamel
6. Small teeth,

7. Cracked enamel
II. Addition of certain features to reduce bond strength
1. Moderate mechanical retention features, grooves etc
2. Use meal mesh in base (but poor aesthetics)
3. Reduce silane coupling
4. Select weaker bonding resin
Enamel fracture and debonding
1. Risk of bracket fracturing and being inhaled, swallowed or flying ceramic
fragment missile.
2. Sharp fragments may be left on teeth requiring time consuming removal with a
diamond bur in a high speed handpiece.
Solutions
1. Protect eyes and airway.
2. Remove excess of the bonding from around the bracket before debonding
3. Keep a finger over the bracket to prevent it becoming a projectile;
4. Apply the debonding pliers on the mesial and distal of the bracket;
5. Main force is squeezing (at least 75%), and very gently twist
6. Specialised debonding techniques like:
Special debonding pliers
Ultrasonic instruments
Electro-thermal to soften adhesive prior to debonding
Laser debonding
3M unitek incorporate a stress concentrator at the base of the bracket to make their
removal easy.

Cost
Basically ceramic brackets are EXPENSIVE
Advantage
THE ONLY CURRENT ADVANTAGE OF CERAMIC OVER METAL BRACKETS
IS....AESTHETICS
Clinical requirements of the orthodontic wires
A. Aligning
 It is defined as vertical levelling between adjacent teeth also takes place but not for
the arch as a whole.
 Types of aligning wire:
1. Looped stainless steel
2. Elgiloy
3. Multi-strand stainless steel wires
4. Nickel titanium alloy wires
 The appropriate wire for this stage has to exhibit
1. Good springiness,
2. Low stiffness,
3. Shape memory
4. Continuous force
5. Small diameter: Easy movement of the wire through the bracket thus promoting efficient
leveling and aligning. Therefore a wire of small diameter is at an advantage. Major
drawbacks include cost and rollercoaster effect
Canine:
It should be constantly borne in mind that any attempt to save time by applying
excessive force in retracting canines has the adverse effect of tipping the crowns distally,
so reversing root uprighting, deepening the overbite, distorting the arch form and wasting
anchorage. This will simply lead to prolonged re-uprighting thus extending overall
treatment time and a possible crisis in anchorage management.

 The mesial tip in the brackets of the SWA particularly that of the canines, makes this an
anchorage demanding phase of treatment, more so if the canines are distally angulated.
Because of this unique feature, care during aligning is paramount for successful treatment.
B. Retraction of individual tooth to relief crowding or ML correction at the initial stage
The base arch, normally .018 or .017 x .025" stainless steel, has to exhibit good stiffness
and strength to resist distortion during the movement of teeth along the wire
C. Overbite control & Space closure
OB control
The wire used for this purpose are:
19*25ss flat or with curve
19*25 rocking chair
Auxillary AW
Segemental or sectional AW
The Straight Wire Appliance controls overbite in two distinct stages:
a) The correction of the mesio-distal tip of the teeth, particularly the canines, in the initial
stages of levelling and aligning.
b) Having corrected the tip of the teeth, the correction then occurs in the vertical plane by
the following methods which are common to all types of mechano-therapy.
i) Extrusion of the posterior teeth.
ii) Intrusion of the anterior teeth.
iii) Proclination of the labial segments.Space closure is accomplished with auxiliaries.
Space closure
1. Sliding mechanics: Various forms of elastic traction, closing modules, powerchain, elastic
bands, Niti closing coil springs have been shown to produce more rapid and consistent
space closure (Samuels, 1993).
2. Closing loop mechanics
D. Torque control
1. The base arch for the final stage of treatment is .019 x .025 SS
2. When individual torque is needed, eg. if 2 or 3 have palatal roots, a wire is needed which
can produce a much lower force over a longer range such as
3. .019 x .025 TMA. The downside is the loss of overbite control.

Archwire sequence guide
The general concept is to think in terms of four main wires, around which other wires are
used as intermediate 'stepping stones' between the main wires
or to achieve specific objectives.
Four main wires:
1) .014 or .016 nickel titanium aligning arch, either active austenitic or active martensitic
depending on the degree of malalignment. It is easier to fully engage martensitic wire as it
is softer at room temperature.
2) .018 round stainless steel base arch for sliding individual teeth mesio-distally, usually to
close labial segment spacing or to retract canines.
3) .017 x .025 SS or .018 x .025 Niti to initiate correction of torque differential in adjacent
teeth.
4) .019 x .025 stainless steel final base arch for overbite control, torque and space closure.
5) Intermediate 'Stepping stone' wires: usually From 1) to 2)
If starting with .014 Niti, a .018 Niti or .016 Steel wire may be necessary for 4 to 6
weeks.
Early use of square (.020 x .020) Niti is particularly applicable where torque discrepancy
is high before engaging 19*25 NiTi.
However a study by Mandal et al 2005 showed the following: The aim of this study was
to compare three orthodontic archwire sequences. One hundred and fifty-four 10- to 17-
year-old patients were treated in three centres and randomly allocated to one of three
groups: A = 0.016-inch nickel titanium (NiTi), 0.018 × 0.025-inch NiTi, and 0.019 ×
0.025-inch stainless steel (SS); B = 0.016-inch NiTi, 0.016-inch SS, 0.020-inch SS, and
0.019 × 0.025-inch SS; and C = 0.016 × 0.022-inch copper (Cu) NiTi, 0.019 × 0.025-inch
CuNiTi, and 0.019 × 0.025-inch SS. At each archwire change and for each arch, the
patients completed discomfort scores on a seven-point Likert scale at 4 hours, 24 hours, 3
days, and 1 week. Time in days and the number of visits taken to reach a 0.019 × 0.025-
inch SS working archwires were calculated. A periapical radiograph of the upper left
central incisor was taken at the start of the treatment and after placement of the 0.019 ×
0.025-inch SS wire so root resorption could be assessed. There were no statistically
significant differences between archwire sequences A, B, or C for patient discomfort (P >
0.05) or root resorption (P = 0.58). The number of visits required to reach the working

archwire was greater for sequence B than for A (P = 0.012) but this could not be
explained by the increased number of archwires used in sequence B.
Factors influencing friction
1. Bracket material.
2. Archwire material
3. Archwire shape
4. Archwire size
5. Slot size
6. Bracket width
7. Bracket / archwire angulation
8. Surface roughness of the archwire or bracket
9. Ligature material
10. Force of ligation
11. Biological factors like saliva, plaque and acquired pellicle
12. Force from occlusion
Mechanics of tooth movement
MOMENT = FORCE x DISTANCE
1. With a removable appliance, the force (X) is applied at a distance (Y) from the centre of
rotation (CR) and results in a tipping movement or moment of XY.
2. With a fixed appliance, a counter-moment of XY can be applied which neutralises the
tipping moment. The resultant force acts through the CR and bodily movement of the
tooth occurs. This is the principle of passive torque force.
3. If the counter-moment is greater than XY, [for example (X + A)Y ] the tipping movement
is neutralised but in addition a moment is generated in the opposite direction (AY). The
CR moves a greater distance than the point of application and apical movement occurs.
This is the principle of active torque force.
Steps of edgewise appliance treatment
1. Alignment and leveling
2. Arch coordination

3. OB and OV closure
4. Space colures
5. Finishing
6. Retention
Pitts 6-5-4-6 approach
Tom Pitts has described an approach to the early stages of treatment which helps
structure the decisions necessary to optimize the effect of early treatment mechanics. This
approach is based on the use of passive self-ligation but it provides a useful structure for
any type of appliance system. This includes:
A. six decisions that should be made at the start of treatment
1. Bracket system and archwire progression
2. Torque selection
3. Tooth recontouring
4. Bracket position
5. Disarticulation strategy
6. Early elastics
B. Five aesthetic and five occlusal features which should be 'read' at each visit.
I. Five aesthetic features to check before Appointment 4
1. Incisor axial inclination
2. Canine and buccal segment axial inclination
3. Gingival display changes
4. Buccal corridors
5. Smile arc development
II. Five occlusal features to check before Appointment 4

1. Bracket height and alignment
2. Vertical levelling and overbite correction
3. Antero-posterior correction
4. Transverse development
5. Arch coordination and interdigitation
C. The fourth visit - photos, panoramic radiograph and repositioning
appointment.
1. About four weeks after placement of the 0.018' x 0.025' archwire, schedule a bracket
repositioning appointment with a new orthopantomogram {may not be necessary) and
some up to date digital photographs of the occlusion.
2. Use this appointment to review torque selection as well as first and second order
bracket position.
3. In addition, review need for further tooth reshaping. This represents the end of the
first stage of finishing.
D. Six aspects to focus on during finishing
1. Check CR=CO
2. Check full correction achieved
3. Check interdigitation and arch coordination
4. Final adjustment of tooth shape and size
5. Gingival shape adjustment
6. Finishing elastics required?
Methods to correct rotation
For anterior teeth
1. Steiner wedge
2. Elastomeric wedge
3. Elastomeric modules
4. Rotation pin as in Begg appliance

5. AW bend or Offset bonding
6. Reciprocal force
7. Rotation spring as in tip edgewise
For posterior teeth
1. Lingual cleats
2. Reciprocal force
3. HG, TPA,
Intraoral auxiliaries
1. Archwire stops
It should be placed in an interdental space anterior to where you want the tooth movement to
occur. Its uses are:
1. Maintaining the archwire in a symmetrical position
2. When bond second molars early on in treatment, turning down the archwire behind the
second molars can cause significant discomfort.
Types
1. Crimpable stops: length 2 mm , Inner lumen size, 016", 0.018" , 0.022"
2. Composite stops are preferred as they are more effective and cheaper than crimpable stops!
2. Archwire hooks
A. Chair side soldered Hooks
B. Presoldered archwires
C. Crimpable hook
3. Torquing auxiliaries
4. Uprighting springs,
5. Rotation springs,
6. Sidewinders
7. Transpalatal bars
8. Quadhelix
9. Lip bumper
The use of lip bumpers is described by Ten Hoeve (1985). Its uses are:

 Molar distalization for correction of mild crowding,
 Very narrow mandibular arches
 Incisor proclination if the lip is hyperactive an resistant to proclination.
 Deep bite correction by molar extrusion and allowing Incisor proclination
 Molar uprighting
 More stable result theoretically because of the slow soft tissue adaptation.
10. Lacebacks (see below)
11. Bendback
1. Used to prevent wire displacement,
2. Control arch length
3. Not used if COS aimed to reduced in non exo cases,
Management of distally inclined canine in deep overbite cases
When the canine is initially distally angulated, overbite control can be compromised and
center line displacement may result during the aligning and leveling phase of treatment.
These problems may be overcome (Khambay, 2006)
1. Sectional appliance, begin by aligning the slots in the buccal segments, including canines.
2. Partial bonding of anterior teeth to allow the canine to upright without proclining the
incisors
3. Partial engagement of the canine
4. Use lace-backs.
5. Control molar anchorage.
6. Use tip edge bracket on canine
7. Progress slowly and patiently.
8. By swapping the canine bracket.
9. The use of an alternative bracket system with less prescription inclination, for example,
the MBT
Customized precision prescription appliances
Customised precision prescription appliances or orthodontic treatment can be delivered by
either:
1. Customising or individualizing brackets

2. Customising the bracket-tooth surface composite/resin interface to the patient’s
tooth morphology and planned treatment needs
3. Customising the archwires
4. Using selected prescriptions to semi-customize the appliance
5. A combination of the above
6. Aligners
Several technologies have come together to allow increased customisation of appliances
to an individual patient’s requirements.
1. Digital imaging
Digital imaging of photographs and radiographs now makes it easy to transmit or upload
patient data to sites that are geographically distant. In addition, the advent of intra-oral
scanners promises the elimination of impression taking.
2. Computer modeling
Computer modelling, design and manufacturing programmers provide an unprecedented
ability to visualize, manipulate and test treatment outcomes. The end results from these
programmes can then be used to construct customized appliances and precision bracket
placement systems
3. Robotics
Robotics is now being introduced to carry out precision archwire fabrication for nickel
titanium, titanium molybdenum and stainless steel archwires.
4. High technology materials and manufacturing technique
Metal injection molding and nickel titanium archwires are two examples of high
technology materials and manufacturing technology which facilitate customized
appliances through high precision, economical use of materials and minimal finishing
requirements.
Advantages
1. The digital records eliminate the need for plaster models and the disadvantages of plaster
study models in relation to manufacture, storage and retrieval mean that the future of
traditional plaster models has to be in serious question.
2. Reduced bonding and set-up time
3. Reduced stress of bond-up:
4. Allows placement of brackets and appliances by less experienced personnel

5. Reduced treatment time
6. Reduced cost ;although the initial cost is higher, this may be recouped if less visits are
required and treatment times are shorter

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