3. To the layperson it may
be thought to mean
simple straightening of
the teeth; however, in
orthodontics the term
has a more
comprehensive meaning.
4. initially Mulligans bypass arch
of
0.016 inch Australian wire was
used to retract canines and then
allow for decrowding by using
round super elastic Niti
archwires. After 15 months of
alignment NiTi round wires were
discontinued. Levelling was done
by rectangular NiTi of
0.017×0.025 inch. Retraction and
closure of existing spaces was
then started by use of 0.019 x
0.025 inch rectangular stainless
steel wires
5. Alignment may be defined as the
movement of the teeth into their
correct relative positions in
relation to a planned dental arch
form in order to achieve the
desired/planned facial and smile
aesthetics and optimal dental-
occlusal function
6. Complete bonding & banding in
both maxillary and
mandibular arch done, using
MBT-0.022X0.028” slot.
Initially a 0.012” NiTi wire was
used which was followed
by 0.014, 0.016”, 0.018”, 0.020”
Niti archwires following
sequence A of MBT. After 6
months of alignment and
leveling NiTi round wires were
discontinued. Retraction
and closure of spaces was then
started by use of 0.019”
x 0.025” rectangular NiTi
followed by 0.019” x 0.025”
rectangular stainless steel wires.
Reverse curve of spee in
the lower arch and exaggerated curve
of spee in the upper
arch was incorporated in the heavy
archwires to prevent the
excessive bite deepening during
retraction process and also
to maintain the normal overjet and
overbite.
7. Alignment thereby involves
movement of the teeth
horizontally/radially and vertically,
predominantly by forces generated by
the archwire engaged in the brackets,
and in terms of correcting three-
dimensional crown and root
angulation, inclination and rotational
position by rotational movements..
8. That is, alignment involves all
the following types of tooth
movement. •
Horizontal/radial: in–out
movements. • Vertical: up–
down movement. •
Rotational: tip, torque, and
rotation round the tooth’s
long axis.
9. In the early days of fixed
appliance orthodontics,
even thin, round, stainless
steel archwires were too
rigid and could not be
engaged in misaligned
teeth. Therefore, the
flexibility of the system
was increased by the
incorporation of loops into
the archwire at
appropriate locations .
Multiloop archwire: this image
shows classic Begg treatment.
10. The looped sections were more
flexible radially to the dental
arch than vertically, and
bending loops into the
archwires was rather time-
consuming and required skill.
The generated forces were
rather complex with unforeseen
adverse tooth movements
sometimes occurring
11. These problems were circumvented
by advances in archwire materials
technology, particularly the advent
of flexible nickel titanium alloy
(NiTi) and titanium molybdenum
alloy (TMA), which led to a move
away from looped archwires to plain
flexible archwires of low flexural
rigidity for the initial alignment
phase of treatment
12. . Thin and thereby more
flexible round archwires are
used initially and as the dental
alignment progressively
improves the orthodontist
works up through
progressively thicker wires
until a full-size archwire can
be engaged.
13. Alternatively, somewhat thicker
archwires of low flexural rigidity
(such as braided steel, NiTi or
TMA) may be used, though this
is generally not recommended as
it may place unnecessarily large
forces on the roots, which at this
crown aligning stage is not
required.
14. Bracket Positioning Variations:.
It is worth checking
dental study models at
the chairside before
bracket placement in
order to improve the
accuracy of bracket
positioning.
15. It may also be worth checking
panoramic radiographs which,
though not particularly accurate,
provide an indication of root
angulations, and this may aid
bracket positioning.
Bracket Positioning Variations:.
16. Following a thorough
diagnosis and establishment
of a treatment plan, and
depending on the prescription
of the bracket system to be
used, there are a number of
local bracket variations which
may be useful .
17.
18.
19.
20. Such bracket variations
can make treatment
more straightforward
and reduce the
requirement for
additional mechanics
and wire bending later in
treatment.
21. It is important to state
that the appliance
system and bracket
prescriptions are not as
important as the
clinician’s understanding
of their utilisation.
22. Experienced orthodontists
may sometimes mix
brackets from different
systems, taking advantage
of local variations,
depending on the desired
tooth movements.
23. Initial Alignment : Initial
alignment may begin
once the brackets and
molar tubes or bands
have been positioned as
accurately as possible.
24. Initial Alignment : The initial
archwire should be flexible
enough to be fully or at least
partially engaged and tied
into most of the bracket
slots..
25. Whether using elastomeric
modules or steel ligatures
to ligate the archwire into
position, it is important
that the wire is not
excessively deflected in
order to avoid its
permanent deformation.
26. The size, material and degree
of deflection of the archwire
should be such as to place a
light continuous force to
each of the teeth in order to
initiate and sustain tooth
movement into the planned
positions
27. Dental development is such
that tooth buds tend to
develop in relatively normal
positions and it is often
during the eruptive process
that the crowns of teeth
begin to become displaced.
28. As such, unless a tooth bud
begins developing in an
ectopic position, even in
severely displaced teeth,
the root apices tend to be
closer to the correct
position than the crowns.
29. Therefore, the purpose of the
initial aligning archwires is
usually predominantly to move
the crowns of displaced teeth
into better positions, which is
the reason that thin flexible
round archwires are ideal
30. It is not necessary or even advisable
to use flexible rectangular archwires
for initial alignment, as they may
place untoward forces on root
apices, potentially causing greater
patient discomfort, damage to the
root apices and, as labial crown
torque will begin to express in the
maxillary incisors, potentially
facilitating a loss of posterior
anchorage
31. As the desired initial tooth
movement is essentially crown
tipping in a horizontal or
mesiodistal direction, or slight
vertical repositioning of
displaced teeth, no more than
approximately 50 g of force is
required.
32. As far as is practical, the
interaction of the archwire
and bracket slot should be
free from binding (i.e. the
archwire binding against a
bracket, then being released,
usually under the forces of
occlusion and mastication,
moving a little, then binding
again) and friction .
33. The term clearance refers to the
size difference between an
archwire diameter and shape
relative to the size of the bracket
slot. This clearance or play of the
archwire within the bracket slot,
together with the method of
ligation, determine how freely the
archwire can move within the
brackets.
34. The greater the freedom of
the archwire within the
bracket slot, the greater its
manoeuvrability and the
lighter the force that will be
able to initiate and sustain
tooth movement.
35. It follows that the lighter the
forces used for tooth movement,
the more biologically healthy the
system. The forces should be
light enough to stimulate cellular
activity without crushing the
blood supply around the roots,
periodontal ligament and
surrounding alveolar bone.
36. As such, some ligatureless and passive
self-ligating bracket systems may be
better at this initial stage of treatment
as the archwire has excellent clearance
within the bracket
slot, and there is no pressure from
an elastomeric or steel ligature
pushing the archwire into the
bracket slots.
37. Alternatively, the brackets
may be tied loosely with
steel ligatures, which may
work in a similar way to self-
ligation, but may be more
time-consuming as each
tooth has to be ligated
individually.
38. When using thin, flexible, initial
aligning archwires, particularly where
the wire is traversing an extraction
space, a large interbracket span or
bypassing a severely displaced tooth,
an additional stainless steel wire , or
reinforcing sleeves, such as closed coil
spring or plastic tubing cut to size, may
be used to reinforce the wire in the
interbracket span.
39. Reinforcing sleeves reduce
the likelihood of accidental
archwire disengagement or
deformation, particularly
under the forces of
mastication .
40. 0 Archwire reinforcing sleeves. (a) Closed coil spring is very thin
orthodontic wire (0.010–0.012 inch) wound into a coil whose helices are
in contact, thereby rendering it incompressible. It is usually delivered as a
length of coil spring wound round a spool, and is cut to the appropriate
length depending on the intended application, which is usually to
reinforce flexible archwires over long spans and/or maintain a space. (b)
Plastic tubing is also delivered as a long length wound round a spool,
which may be cut to the required length and may be used instead of
closed coil spring, though inevitably it has less rigidity.
41. Individual teeth that are severely
displaced from the line of the arch,
or ectopic teeth such as unerupted
canines or incisors, should usually
not be ligated with the initial
archwire, as their ligation would
lead to uncontrolled
arch form alteration with such
flexible archwires
42. Ideally, such teeth should be
bypassed until the rest of the dental
arch is relatively well aligned and a
stiffer base archwire has been
placed, following which forces may
be applied to the severely displaced
tooth via elastomeric thread or
chain, or via a flexible piggyback
(overlay) archwire, which is a flexible
auxiliary archwire ligated in addition
to the base archwire .
43. The maxillary dental
arch is relatively
well aligned and a
stiff base archwire is
in situ. Force is
applied to the
displaced maxillary
right canine using
elastomeric thread.
44. (a, b) A stiff 0.018-inch stainless
steel base archwire has been
placed and space opened for the
in-standing maxillary lateral incisor
using active compressed coil
spring. With the space created, the
lateral incisor bracket is bonded.
45. (c, d) Force applied to the severely displaced
tooth via a flexible piggyback (overlay) NiTi
archwire, which is a flexible auxiliary
archwire ligated in addition to the base
archwire. The base archwire maintains arch
form while the piggyback wire aligns the
displaced tooth.
46. (e, f) The displaced tooth is
nearly aligned. (g, h) The base
wire may now be removed and
the entire dental arch ligated
with the flexible aligning
47. The base archwire maintains
arch form while the piggyback
wire aligns the displaced tooth.
When the displaced tooth is
nearly aligned, the base wire
may be removed and
the entire dental arch ligated
with the flexible aligning
archwire.
48. Bracket size is an important
consideration in initial alignment
and should be sufficient to permit
effective control of tooth
movement. Mesiodistally narrow
brackets will increase the
interbracket span, making
rotational correction around the
long axis of a tooth difficult.
49. Brackets that are excessively
wide will tend to reduce the
interbracket span, which
thereby increases the stiffness
of even the most flexible
archwire in that interbracket
region, potentially reducing
the effectiveness of tooth
movement.
50. Brackets ideally should be wide
enough to provide rotational
control, but not excessively
wide; from a practical point of
view, brackets should not be
wider than approximately half
the tooth width.
51. Initial flexible archwires tend to
migrate laterally along the dental
arch, which means that even if they
are cut exactly to the correct length
distal to the terminal molar teeth,
their lateral movement, possibly due
to the forces of mastication over time,
means the wire will protrude from
one side while simultaneously coming
out of the opposite side molar tube
52. On the side that the wire is
protruding, it may cause ulceration
of the soft tissues, sometimes
leading to considerable patient
discomfort. Such unwanted
archwire migration may be
prevented by placing a stop on the
wire between two brackets that are
relatively close together.
53. Some wires have
crimpable stops on
them, referred to as
crimpable split tubes,
which just need to be
crimped into the
required position .
54. 3 Crimpable split tubes, which may be
crimped onto the archwire with
Weingart pliers.
55. Alternatively, a small
bead of flowable
composite resin,
known as a composite
stop, may be run onto
the archwire in an
interbracket span and
light cured .
56. A small bead of flowable composite resin, known
as a composite stop, may be run onto the archwire in an
interbracket span and light cured.
57. Neither of these
manoeuvres is
necessary if the
archwire is either
cinched or bend backs
are placed distal to the
terminal molars
58. In some patients, particularly
those with deep bites, well-
interdigitated occlusion and
potentially strong jaw
musculature, the interdigitation
of the dental occlusion
itself may be a hindrance to
initial alignment.
59. In such situations, the
posterior teeth may be
separated just beyond
the resting vertical
dimension and
freeway space.
60. Such temporary bite opening
may be achieved by placing a
removable clip-over anterior
bite plane, bonding a
composite resin anterior bite
plane or bite opening turbo
props bonded palatal to the
maxillary central incisors .
62. Anterior bite opening with a
removable or fixed bite plane
permits vertical clearance to
bond the mandibular arch
and permits easier levelling
of the mandibular dental
arch. However, if there is an
increased incisor overjet,
posterior bite opening may
be required.
63. This may be achieved by
placing glass ionomer
cement over the occlusal
surfaces of the posterior
molars, usually the upper
molars, which makes their
subsequent removal easier .
64. Glass ionomer cement bonded to (a)
occlusal surfaces of maxillary molars or (b)
mandibular molars, to open the anterior
bite.
65. With this latter posterior bite
opening
approach, it is important that
the mandibular dental arch
is bonded in order to avoid
uncontrolled overeruption of
the mandibular incisors
66. (a) Deep incisor overbite malocclusion. (b)
Mandibular arch has been bonded, with glass
ionomer cement on the occlusal
surfaces of maxillary first molars providing
the required anterior bite opening.
67. Sometimes brackets
cannot be ideally
positioned during
initial placement, e.g.
partially erupted teeth,
severe imbrication
or severely rotated teeth.
68. In subsequent appointments,
as the brackets become better
aligned on the archwire,
any initial bracket positioning
discrepancies become more
apparent.
69. Therefore, reassessment of
dental alignment and
bracket positions should be
undertaken at each
subsequent
visit, as bracket positioning
errors can be better elicited
once the dental arches are
better aligned.
70. Missed bracket
positioning errors result in
incorrect tooth positions even
though the archwire may be
passive within the bracket
slots
71. At this stage the clinician must
decide whether to
reposition the brackets more
accurately, or alternatively to
place bends in subsequent steel
wires to compensate for
any inaccurate bracket positions.
72. As a general guideline,
the earlier it is in the treatment
process, the more efficient
it will be to reposition the
brackets rather than placing
bends in every subsequent
archwire.
73. A convenient time to
reposition brackets is when
undertaking repairs or picking
up second molars during
treatment, as the clinician may
need to drop down to lighter
archwires anyway.
74. Choice of Archwire: Size and
Material :
Although metric measurements
are commonly used in
orthodontic practice, archwire
and bracket slot dimensions
are still described in imperial
units .
75. Initial alignment requires low friction
and good bracket clearance that allow
relatively free
movement of the archwire within the
bracket slots. When
using an 0.022 × 0.028-inch bracket
slot, the initial archwire
is usually one of the following :
76. Note: A useful
technique for
approximate
conversion from
imperial to
metric units is to
divide the last two
digits of the imperial
measurement by 4
and move the decimal
point in front of the
resulting number. For
example, 0.018-inch
wire, divide 18 by 4,
which gives 4.5, and
move the decimal
point, giving 0.45 mm.
78. Choice of Archwire Size and
Material
Although metric measurements
are commonly used in
orthodontic practice, archwire
and bracket slot dimensions
are still described in imperial
units
79. initial alignment requires low
friction
and good bracket clearance that
allow relatively free
movement of the archwire
within the bracket slots. When
using an 0.022 × 0.028-inch
bracket slot, the initial archwire
is usually one of the following:
80. • Superelastic nickel titanium:
this is the most commonly
used initial round archwire. The extended
flat load–deflection curve for this
material makes it
theoretically very useful for initial
alignment, as it
places a relatively low, continuous force
over a considerable
range of deflection .
81. • Superelastic nickel titanium:
Sizes vary from 0.012 inch (in
severely
crowded/rotated teeth, in adults
and in more anxious
children where the discomfort of
the first archwire is to
be kept as mild as possible), 0.014
inch (the most commonly
used initial archwire), or 0.016 inch
(when the
teeth are not excessively crowded
or rotated).
82. Attempting
to place too large an
archwire too early will
result in
excessive patient discomfort
and increase the likelihood
of brackets debonding or
deformation of the
archwire.
83. • Thermally active nickel
titanium: these heat activated
NiTi archwires may be larger
round (e.g.
0.018 inch), square (0.016 ×
0.016 inch) or rectangular
(0.016 × 0.022 inch) in cross-
section.
84. Although
some manufacturers
recommend use of these
square or
rectangular archwires for
initial alignment, we would
recommend round archwires
for this stage, due to the
reasons already discussed.
• Thermally active nickel
titanium:
85. These wires may be relatively
passive when cold, allowing
easier ligation of chilled
wires, and begin delivering
the required forces only
when they reach mouth
temperature.
• Thermally active nickel titanium:
86. Therefore, they
may be kept in a refrigerator
prior to use, or local ice
may be applied to the region of
the archwire to be ligated
most fully (e.g. ethyl chloride or
a form of cold spray
onto cotton wool pellets, with
the frosted pellets applied
to the archwire).
• Thermally active nickel titanium:
87. • Titanium molybdenum alloy
(also known as
beta-titanium): this wire
material, developed by
Charles Burstone specifically
for orthodontics, has a
stiffness and springiness between
stainless steel and
NiTi, but is formable, i.e. the
clinician can bend loops in
TMA if required. However, it has
relatively high friction.
88. • Multistrand stainless steel:
prior to the advent of flexible
NiTi archwires, multiple thin
stainless steel wires
were wrapped together to form
multistrand or braided
archwires. These wires are either
three or more wires of
similar dimensions twisted
together, or coaxial, i.e. three
or more wires of similar
dimensions twisted around a
central core of wire .
(a) Multistrand stainless steel archwire
showing cross-section. (b) Coaxial stainless
steel archwire showing cross-section.
89. The purpose is to
have the elastic deformability
of the individual small
wires combined with the
flexural rigidity of the sum of
the wires. These wires work
relatively well so long as the
dental irregularity is not
significant.
90. When used, these
are usually 0.015 or 0.0175
inch in cross-section. These
wires may have lower cost
compared with NiTi wires,
but they would need to be
removed at each visit and
adjusted to ensure removal of
any distortions.
91. Placement of Lacebacks
A standard laceback is a
stainless steel ligature (usually
0.010 inch) tied passively in a
‘figure-of-eight’ fashion from
the terminal molar hook to the
canine bracket in the same
quadrant.
93. • Prevention or reduction of canine
mesial crown
tip: if the canine tooth is either upright
or distally
angulated, the engagement of the
initial archwire into
the canine bracket will lead to mesial
crown angulation
as the mesial tip in the canine bracket
is expressed.
Inevitably, this will also procline
incisors engaged with
the same wire.
the
potential purpose of the laceback
is as follows:
95. (b–d) The end of the long ligature is
squeezed together and twisted to form a
small loop.
96. (e) The loop is placed over the first molar hook, and
the wire is tied in a
figure-of-eight mode over the premolar bracket and
again over the canine bracket. It is then twisted with
Mathieu pliers and the end is
cut with a ligature cutter, leaving approximately 3mm
of twisted wire (f) which is tucked under the canine
bracket with a ligature
tucker.
97. serves to tie the canine crown
back to the terminal
molar, maintaining its sagittal
position such that the
change in angulation of the canine
is encouraged to
occur by distal root movement
rather than mesial crown
tip .
To counteract this effect, the laceback
98. A laceback will serve to
maintain the sagittal
position of the canine
crown, so that the mesial
tip expression of
the canine bracket tip
will correct the
angulation of the tooth
by
distal root movement
rather than mesial crown
tipping.
99. Dental midline correction: unilateral
lacebacks may
be used to restrict mesial canine
crown movement
on one side, thereby allowing the
expression of the
mesial tip of the contralateral canine
to aid in dental
midline correction. The dental
midline will thereby
move towards the side with the
laceback
100. • Archwire protection from
masticatory forces: masticatory
forces, particularly over a bolus of
food,may lead
to vertical forces on thin initial
archwires causing them to
disengage fromthe brackets or molar
tubes. The laceback
provides some protection against this
occurring, particularly
in premolar extraction sites where the
initial archwire
is unsupported for a greater
interbracket span.
101. • Canine retraction: theoretically,
tight lacebacks may be
used to begin canine retraction in
cases with severe lower
incisor crowding. However, they
are unlikely to be very
effective as they will not be
active over anything more
than a very short range.
Elastomeric chain may be more
beneficial in such situations .
102. Fully Twisted Tie-back/Laceback
The standard laceback
described has the
disadvantage of
loosening over time.
Although it can be tightened
at subsequent
visits, when the
requirement to avoid mesial
tipping
of the canine crown is
greater, the laceback may be
placed as a fully twisted tie-
back.
A twisted tie-back.
103. Fully Twisted Tie-back/Laceback
The molar, premolar(s)
and canine are tied together
tightly by twisting the stainless
steel ligature continuously
between the interbracket
spans.
The tie-back wire is usually
placed and twisted with
Mathieu
pliers, which twists the wire
from the engaged beaks of
the pliers towards the bracket .
A twisted tie-back.
104. An alternative
But more technically challenging
method is to tie the stainless
steel wire using Coon’s ligature-
locking pliers, which
have a reverse action to
conventional ‘outside-in’ ligature
tying methods, i.e. the initial twist
of the wire occurs at the
bracket, with the continued
rotation of the pliers twisting
away fromthe bracket . This gives
the ligature
a very tight fit around the
brackets.
105. (a) Coon’s ligature-locking
pliers. (b) These have a
reverse action to
conventional ‘outside-in’
ligature tying
methods, i.e. the initial twist
of the wire occurs at the
bracket,
with continued rotation of
the pliers twisting away from
the
bracket. (c) This gives the
ligature a very tight fit
around the
brackets.
106. Elastomeric Chain ‘Laceback’
Another alternative to the
standard stainless steel wire
laceback
is to ‘laceback’ the canine
bracket to the molar tube
using elastomeric chain. This
should not be active in the
sense of moving the canine
crown distally, but just active
enough to counteract the mesial
crown movement of the
canine.
107. chain, which is placed from
the hook on the first molar
tube, engages the premolars
as required, but should only
engage the distal wings of the
canine brackets. This will
prevent unwanted
mesiobuccal rotation of the
canine tooth. Elastomeric
chain lacebacks may be placed
under or over the initial
archwire.
It is preferable to use ‘open’,
i.e. spaced elastomeric
Elastomeric chain that is slightly
active may be
used to tie back the canine crown to
the first molar.
108. Methods of Archwire Ligation
A ligature is a tie that
secures an archwire, or
sometimes
other auxiliaries, into
bracket slots. Placement of
ligatures
is referred to as ligation, or
tying-in of an archwire.
Ligatures are usually tied
under and around a
bracket’s
tie-wings.
109. With initial aligning archwires,
lightly pre-stretched
elastomeric ligatures (modules or
rings) may be used
to ligate the archwire at the first
visit. Elastomeric modules
are available under a variety of
proprietary names, but
essentially they are small round
bands of elastomeric
material that is stretched around a
bracket’s tie-wings to
hold an archwire in position.
110. They are usually held in
mosquito pliers (also termed
haemostats), which have
a mechanical locking mechanism
located between the
handles. It is not essential for the
initial aligning archwire
to be fully engaged into every
bracket slot at this visit, which
could potentially cause
considerable patient discomfort
in the first few days following
archwire placement.
111. Teeth
that are severely malaligned
or rotated may be partially
engaged over the required
number of bracket wings,
and
teeth that are vertically out
of position may be engaged
occlusal to the bracket slot in
order to limit archwire
deflection
112. (a) To align teeth that are vertically out of position, an elastomeric module is first
placed onto the aligning archwire.
(b) The archwire is subsequently placed into the molar tube, and with the wire
maintained occlusal to the bracket on the vertically
displaced tooth, the elastomeric module is stretched and ligated over the entire
bracket. This limits archwire deflection. (c) The other
teeth are subsequently ligated as required; the maxillary lateral incisor is shown
partially engaged.
113. At the first adjustment visit,
usually
approximately six to eight weeks
following initial archwire
placement, and at subsequent
adjustment visits for
continued alignment, it will
usually be possible gradually
to more fully ligate any teeth
where the archwire was not
completely seated in the bracket
slot.
114. The major advantage of
elastomeric modules is their
ease of use and speed of
placement. However, their use
carries significant drawbacks. They
may fail to fully engage
an archwire when such
engagement is intended. One way
around this is to use a ‘figure-of-
eight’ ligation method, though
this will significantly increase
friction.
115. Another disadvantage is the
substantial degradation of
their mechanical properties in
the oral environment, with
significant force relaxation
occurring within days of
ligation, potentially leading to
reduced wire engagement
over time.
116. The use of elastomeric modules
can work relatively well
in situations where the desired
movement of the teeth is
by the brackets being pulled along
with the archwire as it
is returning to its original shape.
However, where greater
sliding of teeth is desired, itmay
be better to ligate the archwire
lightly with stainless steel
ligatures .
117. The
pivotal word here is ‘lightly’, as
excessive tightening of steel
ligatures will have the opposite
effect, potentially hindering
initial alignment. Inevitably, steel
ligatures take longer
to place and remove than
elastomeric ligatures, which
is their main drawback. Steel
ligatures are made from
annealed stainless steel wire,
usually 0.010 inch, although
sometimes 0.012 inch may be
used, such as in Kobayashi
ligatures .
118. The Kobayashi ligature’s legs are welded together to form a
helical hook at its end, permitting attachment of
orthodontic elastics. (a) Standard ligation of a Kobayashi
ligature. (b) Figure-of-eight ligation of a Kobayashi ligature.
119. These ligatures are usually held
with Mathieu pliers (which have
a positive-locking ratchet
and spring for easy opening and
closing) and are engaged
under the bracket tie-wings and
twisted around the bracket
until they are as tight as
required.
120. The excess wire is cut
with ligature cutters and the
twisted end is tucked under
the archwire and bracket wings
with a ligature director
(wire tucker) . It is important that
care is taken
at this stage in order to prevent
sharp ligature ends untwisting
and causing trauma to the
patient’s mucosa between
appointments.
121. When a tooth is severely rotated,
the bracket should
be bonded as far as possible into
the rotation. At subsequent
adjustment visits, if full
engagement of an aligning
archwire into a severely rotated
tooth is difficult, a useful
technique is to place a length of
dental floss around the
archwire and thereby pull the wire
lingually into position
while simultaneously ligating it
with a steel ligature.
122. (a) A severely rotated lower left first premolar, with
the bracket positioned as far into the rotation as
possible. (b, c) A
length of dental floss is tied around the archwire
and pulls it lingually into position.
123. (b, c) A
length of dental floss is tied around
the archwire and pulls it lingually
into position.
125. Alternatively, self-ligating brackets
may be employed,
which may be very useful at this
initial alignment stage of
treatment due to the reduced
friction and relatively unhindered
play of the archwire within the
brackets.Any obstruction
of the relatively free movement
between the archwire
and bracket slots in preadjusted
edgewise systems will delay
the progress of initial alignment
and may lead to anchorage
loss.
126. Cinching versus Bend Backs
Cinching of an archwire refers to
the placement of an
acute bend (usually at
approximately 90∘ to the archwire
in
a gingival direction) on the
archwire exactly as it exits distal
to the terminal attachment in an
orthodontic arch, usually
the most distal molar tube (Figure
14.28). If the acute bend
on the archwire is not exactly as it
exits the molar tube or
other distal attachment, then it is
not a cinch.
127. A cinch refers to the placement of an acute bend
(usually at approximately 90∘ to the archwire in a gingival
direction) on the archwire exactly as it exits distal to the
terminal attachment in an orthodontic arch, usually the most
distal molar tube. It serves to limit incisor proclination during
alignment and levelling, and prevents archwire migration in the
interval between patient appointments.
128. Cinching versus Bend Backs
The purpose
of a cinch is to reduce, as far as
possible, the tendency to
increase in the arch length, and
to limit incisor proclination
in the alignment and levelling
stages of treatment;
the evidence for their
effectiveness in this regard
requires
further investigation.
129. Technically, it is possible
to place a cinch in a NiTi
archwire by bending it
beyond the point of
elastic deformation.
This may be undertaken
using a Weingart plier.
130. Cinching an archwire without exposing the end to an open
flame. (a) Approximately 2–3mm of excess archwire is
maintained distal to the terminal molar tube. (b) The beaks of
Weingart pliers are placed such that the mesial beak holds the
attachment away from the base. This is important to avoid
inadvertent debonding of the tube.
131. (c) Squeezing the pliers places the
cinch on the archwire as it exits the tube. (d)
Cinch in position.
Overall, this technique is
preferred.
132. Alternatively, exposing the 3–
4mm ends of a NiTi archwire
to an open flame with a
miniature orthodontic gas
blowtorch for a few seconds
(the wire will appear orange
to red-hot in the
approximately 650∘C heat)
will significantly
reduce the shape memory
and permit a cinch or
bend back to be placed .
133. Cinching an archwire with exposure of the end to an open flame. (a) Flame
exposure of the 3–4mm ends of
a NiTi archwire with a miniature orthodontic gas blowtorch for a few
seconds. Gloves should not be worn near the blowtorch.
(b) Flame exposure significantly reduces the shape memory and permits a
cinch or bend back to be placed. However, the wire
becomes brittle, and thinner wires may fracture when the bend is being
placed.
134. Thinner archwires,
i.e. 0.012- and 0.014-inch NiTi wires,
tend to fracture with
bending after such flame exposure,
but NiTi archwires of
0.016 inch or larger usually maintain
their bends relatively
well after such flame exposure. This
exposure of an archwire
end to an open flame is sometimes
termed ‘annealing’,
but this is an incorrect use of the term
and should be
avoided.
135. The term annealing (from Old
English onælan,
to set on fire or subject to fire)
refers to a form of carefully
controlled heat treatment
followed by a specified rate and
type of cooling employed in the
manufacturing process of
archwires, used to reduce
hardness and increase the
ductility
of a metal by eliminating the
residual stresses induced
in the wire-making process.
136. Titanium appears to bewell tolerated by
the tissues in the
biological environment, which explains its
biomedical and
dental applications. Nickel ions have been
classified as carcinogenic
chemicals, though it may be that not all
forms
of nickel are carcinogenic, and there is no
supportive evidence
in the implication of nickel released from
biomedical
materials as being unsafe (much larger
prostheses with
higher nickel content are used routinely by
orthopaedic
surgeons).
137. However, exposing an archwire
end to an open
flame is uncontrolled, the extent of
the process along the
length of the wire is unknown, and
the wire becomes brittle
and susceptible to fracture.
Therefore, cinching without
exposure to an open flame may be
considered more
appropriate.
138. A distal-end bend back is a
bend made on the archwire,
usually in a gingival or medial
direction, one or more
millimetres distal to the
terminal attachment (usually
the
molar tube) .
139. (a) A distal-end
bend back in a vertical and
gingival direction. (b) A distal-end
bend back in a medial direction.
140. Bend backs serve to secure the
archwire in position and prevent or
limit lateral sliding
and mesial migration of the
archwire and potential
disengagement
from the most distal molar tubes or
brackets, in
the intervals between patient
appointments, thereby preventing
soft tissue trauma from a
disengaged archwire end.
141. Bend backs will permit a degree
of arch lengthening and
incisor proclination, depending
on the planned number of
millimetres the archwire
extends distal to the molar
tubes
before the bend back.
142. An alternative to
distal-end bend backs
that is available
is known as the ‘split
stop’, which is
essentially a wire stop
that is crimped onto
the archwire distal to
the terminal
molar tube .
A split stop, which may be
crimped onto the
archwire as it exits the most
distal attachment.
143. Step-by-Step Archwire
Placement
• Check the accuracy of
bracket placement in the
mouth
and using the dental
study models as a
reference and
guide.
• Select the appropriate
archwire size, shape and
material.
144. Step-by-Step Archwire Placement
• Using the pretreatment
study models at the
chairside, cut
the distal ends of the
archwire to the appropriate
length
with distal-end cutting pliers
in relation to
the study models. The
archwire length is then
checked in
the patient’s mouth.
145. (a, b) The distal ends of the archwire are cut to the appropriate length
with distal-end cutting pliers. (c–e) The
distal-end wire cutter has juxtaposed cutting edges set at right angles to
the long axis of the instrument. As the inner cutting part cuts
the distal end of an archwire, the outer holding part grips the wire
allowing its easy removal from the mouth.
146. (a, b) The distal ends of the archwire are cut to the appropriate length
with distal-end cutting pliers. (c–e) The
distal-end wire cutter has juxtaposed cutting edges set at right angles
to the long axis of the instrument. As the inner cutting part cuts
the distal end of an archwire, the outer holding part grips the wire
allowing its easy removal from the mouth.
147. • An appropriate excess of
distal length is often left on
the
archwire to permit either
cinching or placement of bend
backs. The wire ends may be
heated to facilitate cinching,
although it may be preferable
to use an alternative
approach not requiring heating
of the wire.
148. • Tie lacebacks if required.
• Introduce the archwire into the
molar tubes on either
side, taking care that neither end
cuts the patient’s soft
tissues. The clinician may direct
the wire with their
fingers or usingWeingart pliers.
The midline identifying
marks on the archwire should be
positioned in the
midline of the dental arch .
149. (a) Upper archwires tend to have three identifying marks,
with the middle mark indicating the middle of the wire. (b)
Lower archwires tend to have one midline identifying mark.
150. • Before the first ligature is
placed, inform the patient that
they may get a ‘tight’ feeling as
the ‘wire is about to the
tied’.
• Themost displaced tooth is
usually ligated first, although
it may be useful to ligate one of
the incisors first just
to stabilise the archwire. Proceed
to ligate all the teeth,
either fully or partially.
151. • If using elastomeric modules, the patient
may choose
their favourite colour . The modules are
usually pre-stretched , which increases
their laxity, both for ease of engagement
and potentially
placing lighter forces whilst engaging the
archwire.
Each module is held securely in the
mosquito pliers,
enclosing one border edge of the module
while leaving
enough of the lumen exposed in order to
permit
easy ligation.
152. Elastomeric modules are available in different
colours. Silver is the least noticeable with stainless steel
brackets. Clear modules are available, but tend to pick up stain
between patient visits.
153. Pre-stretching elastomeric modules. (a) Whilst holding the
module firmly with mosquito pliers, a dental probe may be
used to stretch it. (b) Alternatively, the modules may be
lightly stretched as they are removed from their holder.
154. (a) Correct holding of an elastomeric module requires the
mosquito pliers to enclose one border edge of the module
while leaving enough of the lumen exposed in order to permit
easy ligation. (b) Incorrect holding of an elastomeric module
without
exposing the lumen, which will prevent the module being placed
around the bracket tie-wings. (c) Incorrect holding of an
elastomeric
module by insecure pinching of the edge, which will lead to the
mosquito pliers coming off during attempted placement of the
module.
155. Each elastomeric module
is placed around one gingival
bracket tie-wing, then
both occlusal tie-wings and finally
the other gingival
tie-wing . Care should be taken
not to slip,
particularly as elastomeric
modules sometimes snap
during placement. If greater
engagement is required, the
elastomericmodules may be
ligated in a figure-of-eight
configuration.
156. (a–g) Standard ligation of elastomeric modules, placing it around
one gingival bracket tie-wing, then both occlusal
tie-wings and finally the other gingival tie-wing.
157. The module is placed over
one gingival
tie-wing, stretched down
over and under the
opposing
occlusal tie-wing, stretched
laterally under the
adjacent
occlusal tie-wing, and
finally rotated round itself
and stretched up and over
the other gingival tie-wing.
159. • If using stainless steel ligatures,
the archwire may
be directed in position using a
wire tucker. The steel
ligatures are held in Mathieu
pliers, and the narrow
projecting loop of wire is
squeezed between one’s fingers
to narrow it, and the loop is then
turned up at 90∘. This
will make it easier to slide the
steel ligature over and
around each bracket .
160. (a) Stainless steel ligatures are held in Mathieu pliers.
(b) The narrow projecting loop of wire is squeezed
between one’s
fingers to narrow it, and (c) the loop is then turned up
at 90∘, which will facilitate sliding the steel ligature
over and around each
bracket.
162. (g) The excess wire is cut with ligature cutters leaving
approximately 3mm of the twisted end. (h) The twisted end is
tucked under the archwire and bracket wings with a wire tucker.
(i) Steel ligature in situ. The clinician should gently run her finger
over the bracket to ensure that there are no sharp ends of
ligature wire.
163. Steel ligatures,
so long as not excessively
tightened, provide less
friction and less resistance to
sliding than elastomeric
modules. Excessive tightening of
steel ligatures may
also notch and damage the
archwire, potentially inhibiting
the sliding of teeth. The excess
wire is cut with
ligature cutters and the twisted
end is tucked under
the archwire and bracket wings
with a wire tucker.
164. (a) Lower left lateral incisor is mesiolingually rotated. (b) The archwire
is fully seated using a wire tucker, and tied with
the steel ligature while held in position by the tucker. (c) Archwire fully
engaged in lower left lateral incisor.
165. • If using self-ligating
brackets, the requirement for
elastomericmodules
or steel ligatures is obviated.
It is important
that the self-ligating
mechanism is secure.
• The ends of the archwire are
either cinched or bent back
if required, or some other
form of mechanism to limit
archwire migration is
employed.
166. Archwire Removal
When archwires need to be
changed, removal of the ligatures
is required. Elastomeric modules
may be removed
carefully using a dental probe and
stainless
steel ligaturesmay be cut with a
ligature cutter and removed, or
alternatively the twisted end may
be held
in Mathieu pliers and unwound.
167. (a, b) Elastomeric modules may
be removed carefully using a
dental probe.
168. Stainless steel ligatures may be removed by
cutting the plain side with wire cutters, then holding the
twisted side with the same cutters and removing the ligature.
169. Removal of round or thin
rectangular archwires is relatively
straightforward and usually
accomplished using a
tool such as Weingart pliers.
However, in the later stages
of treatment when using a 0.022 ×
0.028-inch bracket slot,
a working archwire of 0.019 ×
0.025-inch or even 0.0215 ×
0.025-inch dimensions may be
required.
170. The removal of
such archwires, particularly
stainless steel archwires, from
molar tubes may be rather
difficult if a traditional pulling
force is applied to the archwire.
The archwire often seems
reluctant tomove, leading to quite
considerable discomfort
for the patient. This is particularly
relevant when changing
the surgical archwires in the early
postoperative period in
the orthognathic surgery patient.
171. A simple method to remove a
heavy archwire without
causing discomfort to the patient
requires utilisation of the
concept of leverage. Having made
sure that the archwire
is not cinched or kinked in any
way, Weingart pliers are
placed on the archwire between
the terminal molars, or
between the terminal molar and
premolar
172. (a, b) With the pivot
point
between the posterior
teeth, the pliers act
as a lever arm, which
is moved in a mesial
arc-type motion and
gently pushes the
archwire out of the
buccal tube.
173. Contrary to the traditional method of
archwire removal,
the wire is not pulled out from the
molar tubes. The pliers
act as a lever arm with the pivot point
being the embrasure
between the teeth. While gripping the
archwire firmly,
the clinician moves the pliers mesially
in an arc-type
motion, gently pushing the archwire
out of the buccal
tubes . The action is repeated until the
archwire is free from the tubes.
174. (a, b) With the
pivot point
between the
posterior teeth,
the pliers act
as a lever arm,
which is moved
in a mesial
arc-type motion
and gently
pushes the
archwire out of
the buccal tube.
175. Space Creation and Redistribution
There are a number of methods of space creation in
orthodontics, and the clinician should be aware of the
advantages and drawbacks of each approach (Table
14.4).
176.
177.
178. Dental extractions are
deliberately at the bottom of
this list. When a decision to
extract teeth is taken,
the clinician should be
confident that it is in the best
interest of the patient and is
a justifiable requirement
to achieve the best aesthetic,
functional and
stable outcome .
179. If in doubt, treatment
may be undertaken with a
therapeutic diagnosis
approach, i.e. begin
treatment on a non-
extraction
basis but inform the patient
from the outset that a
decision to extract dental
units may be required during
treatment.
180. Alignment in non-
extraction cases often
requires
increasing the arch
length, i.e. increasing
the sagittal distance
between the incisors
and the molars (Figure
14.45).
181. (a) Non-extraction alignment of the lower arch on initial
bonding appointment with a NiTi archwire. Note that 2-mm
length of archwire has been left protruding from the distal part
of the terminal molar tubes before being bent back, in order to
accommodate the planned increase in arch length. (b)
Alignment has occurred predominantly by incisor proclination
and concomitant
increase in the arch length.
182. In situations where incisor
proclination is acceptable
or desirable, and depending
on the extent of forward
movement of the incisors that is
required, a planned
length of archwire may be left
protruding from the distal
part of the terminal molar tubes
before being bent back.
183. Therefore, theoretically the
incisors will procline until the
bend backs reach the distal part
of the terminal molar
tubes. Such bend backs in the
archwire are important to
prevent uncontrolled forward
movement of the incisor
teeth, e.g. if the patient misses
subsequent appointments.
184. The impetus for the forward
movement of the incisors is
predominantly from the mesial
tip in the canine brackets,
i.e. as the mesial tip in the canine
bracket is expressed and
the canine crown tips mesially,
the archwire will carry the
ligated incisor teeth forward
with it.
185. Non-extraction treatment
where incisor proclination
is undesirable will require an
increase in arch length
from distal movement of the
posterior dentition (using
headgear or miniscrew
anchorage) and/or
interdental
enamel reduction .
186. Interproximal or interdental enamel reduction (IPR or IDR), also termed
enamel stripping, involves removal of enamel
from the interproximal regions. The technique may be used to generate
variable degrees of space per contact point depending on the
thickness of enamel and tooth morphology. Up to approximately 0.5mm of
enamel per tooth (i.e. 1mm per contact point) may be
removed in the buccal segments, and up to 0.75mm per contact point in the
labial segments. Different methods of enamel reduction
are available, including (a, b) handheld or
188. (e) discs with a slow handpiece (shown here with a guard),
or very fine tungsten carbide or diamond burs with an air rotor (combined with
water cooling to prevent rise in pulp temperature).
(f) An incremental thickness gauge may be used to measure the amount of enamel
removal required; these are usually available in
thicknesses of 0.1, 0.2, 0.25, 0.3, 0.4 and 0.5 mm. The newly exposed enamel does
not appear to be more susceptible to caries, but the
application of topical fluoride varnish is advisable following enamel reduction.
189. Space for alignment
may also be gained fromincreasing
the arch width through
dental and/or dentoskeletal arch
expansion. From an
aesthetic-centred perspective,
non-extraction treatment
should be carefully planned and
managed by the clinician
in order not to produce
excessive incisor protrusion or
proclination.
190. In patients with extremely
severe crowding (greater
than 9mm per arch) where
an increase in arch length is
not desirable or sufficient to
create space for alignment,
and/or where there is
significant incisor
proclination that
is an aesthetic concern for
the patient, dental
extractions
(usually premolars) may be
required.
191. In such situations,
the canines need to be
retracted into the available
spaces to allow for alignment
of the incisors. In extreme
cases of crowding, the
canines may need to be
retracted
independently (possibly with
a sectional appliance before
the incisors are bonded) in
order to avoid excessive
proclination of the incisors.
192. This may require posterior
anchorage reinforcement to
prevent forward movement
of the anchor teeth distal to
the extracted premolars, for
example using a Nance
palatal arch, a combined TPA
and Nance palatal arch , a
lingual arch for
the mandibular dental arch ,
193. A transpalatal arch (TPA) with an
omega loop is
shown combined with a Nance
arch, which has a palatal acrylic
button that rests against the most
superior–anterior aspect of
the palatal vault. A TPA or Nance
button may be used
independently or combined for
potentially greater posterior
anchorage reinforcement.
A lingual arch.
194. TADs or headgear . The
canines may
be retracted and/or distally
tipped using elastic forces,
which in some circumstances,
such as forward positioned
buccal canines, may be
undertaken prior to engaging
the archwire .
195. (a, b) Sectional lower fixed appliance to retract the forward and
buccally positioned lower right canine tooth, prior to
bonding the rest of the mandibular dental arch. This will avoid
excessive proclination of the lower incisor teeth. The elastomeric chain
is attached only to the distal wings of the canine bracket in order to
reduce the tendency for mesiobuccal rotation. Once the canine is
retracted at least partly into the first premolar space, the rest of the
mandibular arch may be bonded.
196. Another useful technique is
the use of stopped arches,
although this would require
an 0.018-inch stainless steel
archwire, and thereby can
only be undertaken when this
archwire can be placed.
197. A stopped arch. (a) A chinagraph pencil is
used to mark the position of the circle loop
(or small U-loop) that will be bent
into an 0.018-inch round stainless steel
archwire. (b) A circle loop has been bent
into position using light-wire pliers.
198. (c) When the
archwire is inserted into the molar tube, it is placed such that
the circle loop is tight against the mesial aspect of the tube,
and the
wire is tightly cinched on exiting the molar tube. (d) The
alternative to cinching the archwire is to tie the circle loop
tightly with a
stainless steel ligature to the molar tube or its hook. The
techniques shown in (c) and (d) will effectively lock the molar
against
retracting forces to the anterior dentition, preventing mesial
molar movement.
199. From an aesthetic-centred
perspective,
extraction treatment should
be carefully planned and
managed by the clinician in
order not to produce excessive
incisor retraction; this ismore
pertinent to the space closure
phase of treatment, but must
also be considered during
alignment.
200. In cases of moderate to
severe crowding (5–8mm
per
arch) where extractions are
required, it is possible to
retract
the canines whilst
simultaneously aligning the
incisor
teeth, i.e. to avoid separate
canine retraction.
