Space closure /certified fixed orthodontic courses by Indian dental academy

SPACE CLOSURE IN
PEA

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


INTRODUCTION
Space closure is an important step on
orthodontic mechanotherapy and is solely dictated
by the clinicians treatment objectives, irrespective
of the method employed.

SIX GOALS OF SPACE CLOSURE.
 Differential space closure, the capability of
anterior retraction, posterior protraction
 Axial inclination control
 Control of rotation and arch width
 Optimum point co-operation and
 Operator convenience

• Space Closure can be accomplished by employing,
Frictionless system
Frictional system
 In frictionless mechanics the teeth are moved
without the bracket sliding along the arch wire and
are accomplished by numerous designs of springs
and loops.
 In friction mechanics or sliding mechanics the
force employed (Elastics, niti coils springs etc,)
produce tooth movements along the arch wire i.e
the bracket slides along the confines of the
archwire.

FRICTIONLESS SYSTEM
In this system desired tooth movement
occurs by application of a known force
system, which encompasses,
(a) Movement to force ratio at the attachment
(b) Constancy of force and moment
(c) Magnitude of force and movement

CLASSIFICATION OF
ANCHAROGE REQUIREMENTS
Group A anchorage: Here
the posterior segments must
remain in their original space
and the entire extraction space is
used for ant. Retraction.
Group B anchorage: This
category describes relatively
symmetric space closure with
equal movement of the posterior
and anterior teeth to close the
space.
Group C anchorage: All
space is closed by protraction of
www.indiandentalacademy.com teeth.
posterior

IDEAL OBJECTIVES
OF SPACE CLOSURE

 The canine contact the
second premolar
 The roots are parallel
 And the occlusal plane is
level


IDEAL OBJECTIVES
OF GROUP-A SPACE CLOSURE
 Perfect maintenance
posterior anchorage

of

the

 No forces should act on the
posterior teeth. Only a force
system resulting in anterior
translation is desired.
 This force system cannot exit
unless all the anchorage units
are extraoral or in the opposite
arch.


ALTERNATIVE APPROACHES TO
OBTAINING GROUP – A ANCHORAGE


FORCE SYSTEM FOR
GROUP – B SPACE CLOSURE
 Translation of anterior and
posterior teeth is required to
achieve ideal space closure.
 An M/F ratio approximating
10/1
is
needed
for
translations.

CRITERIA FOR OPTIMAL
SPRING DESIGN IN
FRICTIONLESS MECHANICS
 Should posses low load deflection rates
 Should deliver optimal force.
 Should deliver proper M/F ratio, which determines
proper center of rotation
Alpha Bend (position): The position anterior to the
extraction site or in terms of loop designs the
shorter / anterior segment.
Beta bend (position): The position distal to the
extraction site or terms of loop designs the
posterior segment.

FRICTION SYSTEM OF
SLIDING MECHANICS
• Sliding mechanics is the term applied to the
moment of the tooth along the archwire.

Two types of Sliding Mechanics
 Movement of brackets along an archwire
 Movement of archwire through brackets


 In the standard edgewise technique, rectangular
archwires could not effectively slide through
bracket slot due to the need for and presence of
1st, 2nd and 3rd order bends in the archwire and
hence closing loop arches were used for space
closure

 The pre adjusted edgewise appliance allowed for
level bracket slot lineup and the use of ‘straight’
archwires which could effectively more through
bracket slots. This allowed for effective sliding of
the teeth along the archwire and hence various
methods of teeth retraction by sliding along a
continuous archwire were developed.

FACTORS INFLUENCING IN FRICTION
(a) Type of bracket (size and width)
(b) Nature of the bracket material
- Stainless steel
- Titanium
- Ceramic
(c) Wire structure
- Nickel titanium
- Stainless Steel
- Chromium cobalt
- Titanium Molybdenum alloy
- Coated composite wire
- Poly carbonate wires
(d) Mode of ligation / self ligating
(e) Nature of the force applied
- Nickel titanium coil springs
- Elastic chain
- Elastic modules
- Magnets

WIRE SELECTION
IN SLIDING MECHANICS

 A wire that produces less friction with the brackets
 Rectangular wire produces more friction than
round wires and larger diameter wires produce
more friction than smaller wires.
 Cobalt-chromium, beta - Titanium and nickeltitanium produce more friction than stainless steel
due to the surface topography of the wires
 0.016 x 0.22″ stainless steel wire in a 0.018 slot
and a 0.017 ″ x 0.025 ″ wire in a 0.022 ″ slot is
ideal for sliding mechanics.
 Ceramic racketswww.indiandentalacademy.com
create more friction than stainless

MECHANICS INVOLVED
IN SLIDING


SLIDING MECHANICS
Advantages
 Minimal wire bending time
 Initial wire placement is less time consuming
 Enhances patient comfort.

Disadvantages
 Confusion concerning the ideal force levels
 The tendency to over activate the elastic and spring
forces, which cause initial tipping, but gives
inadequate rebound time for tooth uprigthing

METHODS OF CANINE RETRACTION
IN SLIDING MECHANICS
 Elastic Module with ligature
 Elastomeric chains
 Coil springs
 J hook headgear
 Mulligan’s V bend sliding mechanics
 Employing Tip Edge brackets on canines

ELASTIC MODULES WITH LIGATURE

 A single elastic module of the type used to secure
archwires to brackets is attached to the canine by
ligature wires extending from the molar.
 These elastic tiebacks are activated 2-3 mm or to twice
their original size to generate approximately 100-150
gms of force

Alternate delivery systems have been found to be
disadvantageous to the elastic modules in the
following aspects.

• Power chains – It gives variable force, is difficult
to keep clean, and sometimes falls off.
• Elastic bands – These are applied by the patient.
Inconsistent results are achieved because of the
cooperation factor.
• Stainless steel coil spring – They tend to deliver
excess force and are unhygienic

ELASTOMERIC CHAINS
 Introduced in 1960’s
 Used for canine retraction, diastema closure,
rotation correction and arch constriction

Advantage
 Inexpensive
 Relatively hygienic
 Easily applied without archwire removal
 Not dependant on patient cooperation

(Continued)

Disadvantages
 They absorb water and saliva
 Permanent staining
 Breakdown of internal bonds
 Stress relocation leads to loss of force and hence, gradual
loss of effectiveness
 The loss of force with time leads to variable levels of
force during the time the power chain is active in the
mouth. This results in decreased effectiveness
 Difficult to clean
 Chances of breakage www.indiandentalacademy.com

CLINICAL CONSIDERATION WHEN USING
ELASTICS FOR RETRACTION OF CANINES
The moment to force ratio is at its lowest at the initial
placement of modules or power chains as the force level is
highest.
This leads to distal crown tipping of the canine. As the
tooth is retracted, the moment to force ratio increases due to
dissipation of the elastic force and binding of the archwire
in the bracket produces a moment tending o upright the
canine root.
To optimize tooth movement sufficient time should be
allowed for the distal root movement to occur.

(contd)
A common mistake is to change the elastic chain or
module too often, thus maintaining high force levels
and a moment to force ratio that produces distal crown
tipping only.
This also causes excessive mesial out rotation of the
canines. Constantly high force levels can cause
excessive hyalinization of the periodontal ligament and
inhibit direct resorbtion around the canine.
If the posterior segment undergoes direct
bone resorbtion at the same time, loss of anchorage may
result. It is therefore recommended that elastic modules
or chain should be changed at an interval of 4-6 weeks
optimize sliding retraction of the canine.

CLOSED COIL SPRINGS
 Introduced to the orthodontic world as early
as 1931.

Stainless steel Coil Spring
Stainless steel coil springs are efficient
methods of canine retraction. They apply
more predictable levels of force compared
to elastic based systems
It has a higher load deflection rate
compared to NiTi springs

NITI CLOSED COIL SPRINGS


Problems during sliding mechanics of
canine retraction using elastic force or coil
spring and their solutions
 Occlusal interferences can hinder canine distalization
- Bite Planes
 Friction and binding between bracket and archwire
may place heavy on anchorage, especially if the canine
starts at an unfavourable angulaton to the wire.
- Power arms
 Poor canine control
- canine retraction by heavier archwire
 Rotation of canine mesiobuccally and molars
mesiopalatally
- Palatal traction using lingual cleats or buttons

INHIBITORS TO CANINE
SLIDING RETRACTION
 Inadequate levelling resulting in archwire binding
 Damaged or crushed brackets causing archwire
binding
 Soft tissue build up in extraction sites
 Cortical plate resistance (narrowing of alveolar
bone in retraction sites)
 Excessive forces causing tipping and binding
 Occlusal interferences
 Insufficient or inconsistent force

DIRECT HEADGEAR
RETRACTION
 J hook headgear, either of the straight pull or high pull
type is clipped on the archwire mesial to the canines to
slide them distally.
 Straight pull headgear allows swifter canine retraction
than the high pull type. However, this may cause
anterior extrusion (perej at al 1980; Hickham 1974)
and unfavourable occlusal plane rotations (Bowden
1978). This may be a problem in high angle cases.
 High pull headgear may cause more bodily retraction
and also aid in bite opening.

HEADGEAR RETRACTION
Advantages
 Extremely conservative of anchorage.
 Sympathetic overjet reduction.
 Can be applied to both upper and lower arches
simultaneously.

Disadvantages
 As force application is intermittent this is slower than
other methods of canine retraction.
 Highly dependent on patient cooperation
 The molar and buccal segment correction is usually
later compared to other systems.
 Canine tipping and anterior extrusion can occur with
the straight pull headgear.

PROBLEMS DURING USE OF J HOOK
HEADGEAR AND THEIR SOLUTIONS
 Occlusal interferences between upper caine cusp
and lower canine or premolar bracket.
- Bite opening
 Mesio buccal rotation of canines
- Sterner’s ties or Rotation wedges
- Heavy archwires
 Flaring of canines into buccal cortex
- The archwire should be kept contracted
across the canine.

MULLIGAN’S V BEND
SLIDING MECHANICS
 Introduced by Mulligan in 1970’s.
 The basic principal was to apply differential moments to
the teeth via bends in the continuous archwire while force
for retraction was applied by auxiliaries like elastic chain,
coil spring etc.
 This is a variation of the normal sliding of the canine along
the continuous wire. In the 0.018 slot, 0.016 SS wire is
used for retraction while in the 0.022 slot. 0.16, 0.18 or
0.020 wires may be used.

(Contd)

• If maximal canine retraction is required the bend is placed
very closed to molar and the bicuspids are not banded. This
causes a strong distal crown moment on the molar which
counteracts the auxillary force tending to move the molar
crown forward. Thus this helps in reinforcing anchorage.
• On the other hand, the longer span of wire towards the canine,
through applying a moment to keep the canine upright, allows
some tipping to occur as the moment is less. Thus the canine
gets retracted by tipping and uprighting.
• As the canine retracts, the bend goes on becoming less off
centre and mesial crown uprighting moments on the canine
increase. After closure of space, a bend maybe placed just
distal to thecanine and the 2nd premolars banded.
• This allow equal and opposite moments on both the canine
and the molar and thuswww.indiandentalacademy.com
allows root uprigting.

(contd)
2nd premolars can be included at the start of retraction
and a bend placed just mesial to them. This also allow
the offset V bends to apply differential moments.
However this is not as effective in anchorage
conservation as placing the bend next to the molar
because the amount of offset is less. In these cases the
offset position is naturally eliminated as space closure
occurs. When space closure is completed the V bend
is centered which allows root parallelism. Thus V
bend sliding mechanics can be used to adjust
anchorage demands and ensure efficient space closure
during cuspid retraction.

Employing Tip – Edge Brackets on
Canines
 Tip Edge brackets may be used on upright or
distally tipped canines
 This design eliminates binding between the
archwire and the slot during the initial stages.
 Uprigthing springs may be used to correct canine
angulation without causing anterior extrusion. Full
size rectangular wires can then be placed to
achieve the desired tip/torque specifications.

METHODS OF CANINE RETRACTION
BY FRICTIONLESS MECHANICS
• Rickett’s maxillary and mandibular cuspid
retraction spring
• Poul Gsessing canine retraction spring
• Burstone T loop attraction spring


RICKETS MAXILLARY AND MANDIBULAR CUSPID
RETRACTION SPRING

 Introduced by Ricketts in 1979.
THE MAXILLARY CUSPID RETRACTION SPRING

 It is a double vetical helical extended crossed closing loop spring
which contains 70 mm of the wire.
 It produces 50 gms per mm of activation.
 3-4 mm of activation are sufficient for upper cuspid retraction
THE MANDIBULAR CUSPID RETRACTION

 It contains 60 mm of wire 16 x 16 blue elgiloy
 It produces approximatley 75 gms of force per mm of activation.

 2-3 mm of activation is required to produce the desired force.

PG RETRACTION SPRING


SEGMENTAL EN-MASSE
EXTRACTION SPACE CLOSURE
T-LOOP RETRACTION SPRING


SYMMETRIC SPACE CLOSURE
– GROUP B ANCHORAGE


MAXIMUM POSTERIOR ANCHORAGE:
GROUP – A SPACE CLOSURE


MAXIMUM ANTERIOR ANCHORAGE:
GROUP C SPACE CLOSURE
• Biochemical principle reverses the approach of the Group
A space closure.
• The alpha moment is increased relative to the beta moment.
• Primary side effect is an extrusive force acting on the
anterior teeth. This can be prevented by inter maxillary
elastics.
• In Group – C space closure, the T-loop retraction spring is
positioned closes to the anterior segment.
• Space closure can be expected to proceed with mesial
tipping of the buccal segment.
• To reduce the horizontal forces, an activation of 4 mm is
recommended.
• The spring should be reactivated approximately 2mm.

RETRACTION OF SIX ANTERIORS
BY – CLOSING LOOP ARCHWIRE
The performance of a closing loop is
determined by three major characteristics:
1. Spring Properties
2. The moment it generates
3. Its location related to adjacent
brackets.


CLOSING LOOP ARCHWIRE


(Contd)
Specific recommendations for closing loop
archwires with the 18-slot appliance and narrow
brackets are:
 16 x 22 wire, delta or T-shaped loops 7 mm
vertical height and additional wire incorporated in
the loop to make it equivalent to 10mm of vertical
height
 Gable bends of 40 to 45 degrees total (halt on each
side of the loop)
 Loop placement 4 to 5 mm distal to the center of
the canine and second premolar with the
extraction site closed

OPUS CLOSING LOOP


CONTINUOUS ARCH
T – LOOP SPACE CLOSURE


Common side effects of space closure using
“continuous arch T-Loops” and their solutions:

1.Side Effect
: Tipping of the anterior and posterior
segments into the extraction site.
Correction : Increase the alpha and beta moments
2. Side effect: Flaring of the anterior teeth
Correction : Reduce alpha moment or increase the
distal activation
3. Side Effect

: Mesial in rotation of the buccal
segments
Correction : Mesial out rotation in archwire,
palatal arch or lingual arch

4. Side Effect

: Excessive lingual tipping of anterior
teeth
Correction : Increase the alpha moment

INTRUSION AND RETRACTION OF FOUR INCISORS BY
BURSTONE’S THREE PIECE INTRUSION ARCH


MAJOR AND MINOR CUSPID
RETRACTION
Minor Cuspid Retraction

Major Cuspid Retraction

• Uncontrolled tipping
• Controlled tipping or
(1 to 2 mm)
translation (> 3 mm)
• Preliminary buccal
• Buccal stabilizing segment
alignment in buccal segment
required
permitted
(a minimum 0.018 x 0.025)
• Required arch length
• Required arch length
>2mm/side
(1 to 2 mm / side)
• Group B or C anchorage
• Group A to B + anchorage
• Distal force greater than 250g
• Distal force less than 250g
• Good cuspid axial inclinaion
• Long cuspid roots
• Cuspids mesioangular

SIMULTANOEUS INTRUSION AND
RETRACTION OF ANTERIORS
USING “K-SIR ARCH”
The K sir arch is a modification of the
segmented loop mechanics of Brustone and
Nanda. It’s a continuous 0.019 x 0.025 TMA arch
wise closed 7mmx2mm U-loops at the extraction
side


K – SIR ARCH


UNWANTED EFFECT OF TOO
RAPID SPACE CLOSURE
• Reduced torque control causes
upper incisors being too upright
at the end of the space closure,
with spaces distal to canines, and
an unesthetic appearance.
• Rapid mesial movement of upper
molars was found to allow palatal
cusps to hang down, resulting in
functional interferences.

(Contd)
“Rolling of teeth adjacent to
extraction site”

 Lower molar tipping with
extrusion of the distal
cusps, especially in high
angle cases
 Excessive soft tissue build
up.

Over coming the possible
inhibitors to sliding mechanics
First order (or) rotational resistance


SECOND ORDER OR TIPPING
RESISTANCE


THIRD ORDER OR
TORSIONAL RESISTANCE


(contd)
Occasionally a small space would open
between the 1st and 2nd molars during space closure
since forces were directed from 1st molars to
anterior hooks on the archwires. This was
managed in one of three ways:
 1st and 2nd molars could be laced together before
beginning space closure.
 Elastic could be extended from the second molar
to the hook on the archwire, in addition to the
elastic or wire tieback attached to the first molar
 The elastic tieback could be extended from the 2nd
molar, instead of the first molar, to the hook on the
archwire.

CONCLUSION
Orthodontic space closure should
be individually tailored based on the
diagnosis, and treatment plan.
The
selection of any treatment, whether a
technique, stage, spring, or appliance design
should be based on the desired tooth
movement. So, having a wide wisdom on
these concepts helps orthodontist to
successfully
achieve
the
treatment
objectives. www.indiandentalacademy.com

THANK YOU


Space closure /certified fixed orthodontic courses by Indian dental academy

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