LOOPS in orthodontics t loop bull loop vertical loop mushroom loop stop loop

CONTENTS
• Introduction
• History
• Orthodontic Forces
• Force Control
• Wire-Clinical Consideration
• Loop activation for force control
• Loop Design
• Bauschinger Effect
• Classification Of Loops
• Vertical Loops
• Horizontal Loops
• Transverse Loops
• Anchorage consideration
• conclusion

INTRODUCTION
• Optimum control of tooth movement requires
the application of a specific orthodontic force
system.
• So we need to have a clear idea about the
mechanics of the orthodontic appliances to
achieve a predictable and desirable result.

How to achieve treatment efficiency?
.1.Continuous forces
2.Acting on a wide area
3.Working in the correct direction(direction in
which tooth is to be moved)
4.Maximum comfort to the patient
All this can be accomplished successfully only by
the precise application of different size, shape
and type of loops, having a control on the
distribution, direction, degree and duration of
force applied.

HISTORY
The principles and uses of vertical loops was first described
by RAY ROBINSON in 1915 who was an early advocate of
light wires and light continuous forces by means of loops.
He summarized that except the force of gravity, there is
probably no force so constant in its operation as that of a
coil spring as even as the pressure of the atmosphere
varies with temperature change.
STRANG was the first to introduce loops into this edgewise
technique.
BEGG IN 1956 explained the advantages of different loop
configuration in arch wire design and activation.

ORTHODONTIC FORCES
Orthodontic forces are of two types
• Primary-Developed in the arch wire and
depend on the resiliency or movement of the
arch wire. This type of force can be
manipulated by increasing the resiliency of a
wire by the incorporation of loops.
• Secondary-Forces that are designed from
auxillary attachments such as finger springs,
rubber bands, headgears etc

BASIC PRINCIPLES OF FORCE CONTROL
• The best way to understand the activity of any
loop is to understand what rules apply to any
deflection in a wire.
• There are 4 D’s in force control
– Degree of force-Amount or intensity of force.
– Distribution of force-The manner in which the
force is transmitted to the root surface or alveolar
process.

– Direction of force -Direction of the force should
be in the plane in which the tooth is to be moved.
– Duration of force -Range of activity of applied
force

CLINICAL CONSIDERATION
• Range Of Deflection -The distance that a wire can
be deflected before it undergoes permanent
deformation.
• Force -An influence tending to change the motion
of a body or produce motion/stress in stationary
object. Calculated by multiplying the mass of the
body with its acceleration.
• Elastic Limit -The maximum extent to which a
solid may be stretched without permanent
alteration of size or shape.

LOOPS in orthodontics t loop bull loop vertical loop mushroom loop stop loop

Variation In Diameter
a. The magnitude of force that can be developed through
deflection of a wire is proportional to the fourth power of
number of times by which the diameter of the wire is
changed.
F * D4
So if the diameter is doubled, the force exerted by it will
become 16 times more.
b. The relationship of the diameter to the maximum load
before permanent deformation takes place varies directly
to the 3rd power of the increase in the diameter.
Total load Capacity * D3
c.The elastic limit will vary inversely with the increase in
diameter.
Elastic limit * 1/D

Variation In Length
• Magnitude of force value per unit of deflection
will decrease in proportion to the cube of the
difference in length.
F * 1/L3
• The force that can be developed, decreases 1/8th
when the length of the wire is doubled.
• Increase in length will proportionally decrease
the maximum load.
• Twice the length allows half the maximum load.
• Elastic limit increases proportionally according to
the square of difference in length.
• Elastic limit * L2

LOOP ACTIVITY FOR FORCE CONTROL
• General rules to be followed
1. Any loop will reduce the force and increase
the range by adding wire in the inter-bracket
span.
2. Any loop may be contoured ‘open’ or ‘closed’.
3. The force of any loop may be reduced by
coiling the wire at the apex one or more times.

4. Loops are most efficiently activated through
compression of the legs.
5. The forces developed in the loop or the
archwire will be transmitted to the tooth
through the bracket attachment as a tipping or a
bodily force depending upon the contour and
method of activation.
6.The force reduction affected by contouring
most loops will be in direct proportion to the
increase in the amount of wire between the
brackets.

LOOP DESIGN
• One important consideration in loop design is
that the legs of a loop should always be
contoured at right angles to the desired direction
of activity
• The loop should be “fail safe”. This means that,
although a reasonable range of action is desired
from each activation, tooth movement should
stop after a prescribed range of movement even
if the patient does not return for a scheduled
adjustment.

• Design should be as simple as possible.
• A loop is more effective when it is closed
rather than opened during activation.

THE BAUSCHINGER EFFECT
• If a straight piece of wire is bent so that
permanent deformation occurs and an attempt is
made to increase the magnitude of the bend,
bending in the same direction as had originally
been done, the wire is more resistant to
permanent deformation than if an attempt is
made to bend in the opposite direction.
• The wire is more resistant to permanent
deformation because of certain residual stress
remains in it after placement of the first bend.

• If a bend is made in an orthodontic appliance,
the maximal elastic load is not the same in all
directions, it is greatest in the direction
identical to the original direction of bending
or twisting. The phenomenon responsible for
this difference is known as bauschinger effect.

CLASSIFICATION OF LOOPS
• According to function(jarabak 1963)
• 1. Vertical : Vertical loop is most efficient in
moving the teeth in antero-posterior
direction.
• 2. Horizontal : moves teeth in vt direction
• 3. Transverse : moves teeth most efficiently in
mediolateral direction.

2. Based on purpose of the loop
(a) Leveling and Aligning
(b) Retraction
(c) Multipurpose
3. Based on presence of helix
(a) Loops without helix(e.g. vertical loop)
(b) Loops with helix(e.g. Helical bulbous loop)
4. Based on function
(a) Opening loops
(b) Closing loops

VERTICAL LOOPS
• Used for first order discrepancies(Labio-Lingual or
mesiodistal)
• The vertical loop has two vertical components and
may be activated in any plane perpendicular to these
components.
• Two types-
• 1. Open-
A. Efficient in opening space
B. Used to rotate a tooth
C. Average rate of decrease of force is 60.5gm/mm

• 2. Closed-
A. Primarily used to close space
Average rate of decrease of force is 41.4gm/mm

HELICAL LOOP
• It is 3 separate springs made up into a single unit.
• Helix could have 1½ turns or 2½ turns , that
would include several millimeters of wire without
making the loop any longer.
• The initial force that is developed is less than that
obtained with a simple loop.
• But, the decrease in force per mm of distance
returned is always less, hence more resilient
active element leading to greater working range.

FUNCTIONS OF VERTICAL HELICAL
SPRINGS
• To increase arch length in one part of the arch for
the repositioning of the malaligned teeth.
• Used as an expansion device to create space for
the alignment of teeth.
• Used as highly elastic rotation device.
• Used to distally drive canines in the treatment of
malocclusion when the 4 1st premolars have been
extracted.
• Minor levelling adjustment can be made to
reduce excessive curve of spee by placing loops
between each of the posterior teeth.

• VERTICAL LOOP-
• Both open and closed vertical loop was given
by Robert Strang in 1933
• Length-6-8mm
• Width-1.5mm
1.Used mainly for retraction of anterior teeth.
2.To open spaces
3.To rotate teeth

• In Beggs mechanotherapy, anterior tooth
alignment is accomplished with archwires
incorporated with vertical loops. The loops
increase the wire span between the teeth and
produce a gentler pressure during movement
• The loops are then activated to produce
overcorrection of rotations, labio-lingual or
mesio-distal movement

• BULL LOOP-
Was given by Harry Bull in 1951
Also known as Squashed Vertical Loop

• USED FOR:
a) Retract the anteriors
b) Closing of spaces
• It is activated by opening the loop
• An advantage of the use of this loop when
used for class II correction in conjunction with
class II elastics is that they do not procline the
mandibular anteriors since the closing loops
restrain this effect

• VERTICAL LOOP WITH HELIX-
Given by Dr Moris Stoner in 1960
Loop incorporated to increase the working range

• The force from the cantilever arms give
direction to this whole force system while the
cross section geometry of the wire, its modulus
of elasticity, diameter, number of turns in helix
and the length of the arms control the force
magnitude of this highly elastic system
• lateral extension coils not only increase
flexibility but also reduce the tendency to tip
adjacent teeth as they are being moved

• OMEGA LOOP-
• Given by Dr Moris Stoner in 1960
• Advantage of this loop is that it tends to
distribute stresses more evenly through the
curvature of loop instead of concentrating
than at apex
• .

• Selected to apply moment to last tooth in arch
• It causes bodily movement of root
• This loop can also be used as a stop loop

• TEAR LOOP
• The ideal force applied to achieve movement
of the mandibular incisors

HORIZONTAL LOOP/BOOT LOOP
• introduced by stoner in 1960
• They are designed such that the active legs are
parallel to the archwire
• Principle value is its reduction of force in the
vertical plane or occlusogingival direction.
• It is effective in aligning the brackets when it is
necessary to open the bite or to depress or
elevate the anterior or posterior segment.
• It is possible to contour the horizontal loop to
press against the gingival area to develop a
torquing activity on the root

• The supraversion and linguoversion of the
maxillary central incisor and infraversion and
labioversion of lateral incisor in class 2 div 2.
• To create effective force to extrude maxillary
canine that has delayed in eruption.

• Efficiency of the double Horizontal Loop is
best when kept on an individual tooth either
above or below the line of occlusion. It can be
activated in an occluso-gingival and labio-
lingual plane but not in the mesiodistal plane.
One loop can be contoured to elevate and the
other loop can be contoured to depress,
tending to tip the tooth or move the roots

• T LOOP-
• Given by Dr Charles J Burstone in 1972
• Can be segmented or unsegmented.
• Helps in closing of spaces.
• Helps in opening of bite.
• When this loop is used with a rectangular wire the
range of torque action is increased,because of the
greater amount of wire in the horizontal plane.So,this
loop eliminates the undesirable occlusal or gingival
deflection of the arch-wire when activated, which may
produce a tipping movement.
• So this loop causes elevation or depression in the true
vertical plane.

Segmented t loop T loop in continuous arch

Asymmetrical T loop
• Asymmetric T loop was
described by James
Hilger in 1992.
• Activation of
asymmetric T loop is
done by compressing
short mesial loop and
opening long distal
loop.

• BOX LOOP-
• Given by Dr A
Sivakumar in 2006.
• Used for alligning of
asymmtric crowding in
early permanent
dentition.
• Root paralleling.
• Uprighting of tipped
molars.

Mushroom loop
• Mushroom loop was given by dr flabio uribe
and dr ravindra nanda in 2003.
• The mushroom loop neither interferes with
the gingival tissue nor does it distort easily
thereby improves the delivery of orthodontic
load.
• Used for closing of
spaces.

Double delta loop
• The double delta loop serves to close spaces.
• It is also frequently used for the leveling and
integration of the arches.

K-SIR arch
• K-SIR arch which stands for Kalra –
Simultaneous Intrusion and Retraction was
developed by Dr. Varun Kalra
• It is a modification of the segmental arch
technique of burstone as applied to
continuous arches

• Its advantages include simplicity in design and
fabrication, comfort to the patient and less
chances of tissue impingement.
• As it carries out en-masse retraction it
abbreviates orthodontic treatment time
compared to conventional edgewise
mechanics.
• Also, this prevents the appearance of an
unsightly space distal to the laterals which is
seen in individual canine retraction.

TRANSVERSE LOOPS
• Moves the teeth most efficiently in the medio-
lateral direction, i.e. tipping of molars, pre-molars
bucally or palatally hence affecting inter-canine,
inter-premolar or inter-molar width.
• The high elasticity at a low force
magnitude,which can be built into a transverse
helical loop appliance, makes this appliance
ideally suited for retrieving palatally erupted
canine and lingually erupted pre-molars.
• It is also used for elevation of submerged pre-
molar in cases where oral vestibule is shallow.

Anchorage considerations in the
employment of loops
• If a desired tooth movement is readily responsive
and the reactionary forces of loop to be used are
directed against teeth in a direction that is highly
resistant, the operator can expect the loop to
accomplish its objective without complications.
• But the operator must be concerned with the
reciprocal forces produced by a loop employed for a
highly resistant movement such as root tipping.
These forces can cause readily responsive tooth
movements to occur in an undesired direction.

• Anchorage in the area adjacent to a loop is
developed through the rigidity of the
comparatively short sections of wire in the
interbracket span
• When two loops are employed on either side of a
tooth and activated in the same plane, the
activity of the combination of loops is confined
essentially to the tooth between the loops and
anchorage is developed in the adjacent teeth
through the rigid section of wire.
• Heavier gauge archwires are better able to resist
displacement when highly resistant tooth
movements are required

CONCLUSION
• The modification of arch wire shape with the
inclusion of loops has been advocated for a
number of reasons. These included
– the improved resiliency of an appliance between
adjacent teeth
– significant reduction in the customary number of
clinical adjustments.
– diminished force values could be applied to
provide improved control over individual tooth
movements

• several different types of loops selected for
specific movement of a single tooth

• Loops are usually included in the initial alignment
archwire to attain bracket alignment, however
loops also may be used in other stages of
treatment, such as
I. Mesial or distal movement– Double vertical
loop or a combination of open and closed
vertical loops.
II. Space closure – closed vertical loop, tied back.
III. Space opening – open vertical loop, with stops.
IV. Bite opening – T loops mesial to canine can be
used

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