This document describes an orthodontic case involving extraction of four first bicuspids to correct crowding. Treatment began with extractions and space closure using elastic chains and Pletcher springs. After five months, space was created for tooth #12 using a sling shot mechanism. Rotation wedges and closed coil springs were used to correct rotations. At seven months, dental midlines aligned but further archwire sequencing was needed to improve alignment, finishing with a .0175 twisted wire.

1. Crowding, Extraction, Sling Shot, and
Torque
Pletcher's spring
Prepared by: Ahmed S. Baattiah
Supervisor: Prof. Maher Fouda

2. Male 16 years old, has severe crowding,
midline deviation (dashed lines)
Crowding, Extraction, Sling Shot, and Torque

3. After several years, resorption
results in a decrease in the
vertical height of the bone, but
more importantly, remodeling
produces a buccolingual
narrowing of the alveolar process
as well.

4. Orthodontic treatment starts with extraction of
four of the 1st bicuspids (.014 Niti).
UL2 complete blockout

7. Force gauge

8. UL2 complete blockout
Orthodontic treatment starts with extraction
of four of the 1st bicuspids (.014 Niti).

9. Five weeks later, .018 ss wires are installed with open
coil spring between UL 1 and 3 and power chain
between UL 3 and 7
Correction of crowding for the lower anterior region is much
easier. A rotation wedge is placed about 1 month post bracketing.

10. Rotation wedges
It acts as a fulcrum between wire and bracket to
correct the rotation. It is ligated to the tie wing of
the bracket.

11. Three months post bracketing, space is being
created for UL 2

12. Four months post
bracketing, a lingual button is placed on UL2 with power chain x7
( sling shot); Pletcher's spring between UL 3 and 7 .
( sling shot)

13. •Provides continuous force for space closure
•size: .012X.030
•50 per pack
Pletcher's spring

14. Pletcher's spring

15. Pletcher's spring

16. Four months post bracketing, a lingual button is placed
on UL2 with power chain x7 (sling shot); Pletcher's
spring between UL 3 and 7 .
(sling shot)

17.  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 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.
Maxillary 0.016-
inch stainless
steel archwire
with power
chains to retract
canines.

18.  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
resorption around the canine.
Uncontrolled tipping with force bypassing
the CRes. Note that the CRot is apically
displaced.
Disadvantages of elastic modules

19.  If the posterior segment undergoes direct bone resorption 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.
Bone resorption of the posterior segment

20.  Most of the elastomeric chains generally lose 50-70% of
their initial force during the first day of load application
and at the end of 3 weeks retain only 30-40% of their
original force.
 To overcome the problem of rapid force decay rate and
provide for a more constant and consistent force delivery,
prestretching of E chain has been suggested. But with
this the increase in residual force at 3 weeks is only 5%
coupled with a 50-75% reduction in the initial force after
prestretching.
Lose of power chain

21. (4,5 months post bracketing).

22. (4,5 months post bracketing).

23. Five months into treatment, cross bite of UL2 is corrected;
there is no space between UL3 and 5, but
there is space between UR 3 and 5.

24. Notice the rotation of UR 3 due to retraction of
the closed coil spring
One month of closed coil spring (150 gms-9mm) results
in the closure of the space between UR3 and 5 .

26. At the same appointment, there is enough
space for UL 2

27. It is immediately corrected
when a rotation wedge is placed on the mesial of UR3
However, there is an instant separation of
UR 3 and 5. The closed coil spring has to be used .

28. Seven months of treatment, the dental midlines coincide
(dashed lines).
Extraction spaces have been closed or being closed
UL 2 has been moved into the arch But the alignment
needs to be improved with arch wire sequence for a second
time starting with .0175 twisted wire .

30. Extraction spaces have been
closed or being closed
But the alignment
needs to be improved with arch wire sequence for a second ti
me starting with .0175 twisted wire .

31. UL 2 has been moved into the arch
But the alignment
needs to be improved with arch wire sequence for a second
time starting with .0175 twisted wire .

32. UL 2 has been moved into the arch
But the alignment
needs to be improved with arch wire sequence for a second
time starting with .0175 twisted wire .

33. The alignment of UL2 improves one month of using
.016x.022 ss wire with introduction of torque.
(total 14 months of treatment )