Pg canine retraction spring

A SIMPLIFIED APPROACH
TOWARDS
PG CANINE RETRACTION SPRING
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OVER VIEW
• INTRODUCTION
• CANINE RETRACTION
• PG CANINE RETRACTION SPRING
• MODIFIED SPRING
• FUNDAMENTAL BIOMECHANICS
• CASE REPORTS

INTRODUCTION
NIKOLAI defined OPTIMUM ORTHODONTIC
FORCE “as that which produces a maximum
desirable biologic response with minimum tissue
damage, resulting in rapid tooth movement with
little or no clinical discomfort”.

SECTIONAL MECHANICS :
Sectional arch technique facilitates the
creation of an optimal force system fulfilling the
biomechanical requirements imperative for
planned movements.

CANINE RETRACTION
 FUNCTION
 STABILITY
 EASTHETICS

CANINE RETRACTION
 Friction mechanics :
Sliding the canine through arch wire gives undesirable
side effects.
• Binding
• Friction
• Extrusion rotation
• Distal tipping
• Bending of arch wire
• Temporary or permanent stops in the tooth movement

 Frictionless mechanics :
• Accomplishes space closure by means of
retraction springs.
• Making it possible to apply predetermined and
precise forces which can meet the biomechanical
requirements for planned tooth movements.
• Friction and binding of the tooth are
eliminated.
• Tipping and rotations can be controlled.

NEED FOR MODIFICATION
 ORIGINAL SPRING IS
• Complex and bulky,
• Less comfortable to the patient,
• Problem in maintaining oral hygiene,
• Difficult in fabrication,
• Difficult in activation.

SELECTING TMA OVER STAINLESS
STEEL•High spring back and formability, with low stiffness,
•High ductility,
Making it suitable for a number of treatment
modalities.
The high ductility of TMA allows it to be formed
into arches are segments, with complicated loop
configurations.
Specialized springs or auxiliaries fabricated from
“TMA allows for simplification in design in achieving
identical force delivery”.
“SUPERIOR FORCE SYSTEMS WITHwww.indiandentalacademy.comwww.indiandentalacademy.com

Superiority over S.S.
1. TMA can be deflected twice than S.S. as far without
permanent deformation,
2. Working range of TMA is 1.6 times that of standard
S.S.,
3. TMA has modulus of elasticity less than that of S..S.,
4. Extra oral anchorage demands with TMA wires are
less than those for s..s.,
5. Spring back for TMA is superior to that of S.S.,
6. TMA has corrosion resistance comparable to S.S.www.indiandentalacademy.comwww.indiandentalacademy.com

7. Spring back for TMA is superior to that of S.S.,
8. TMA has corrosion resistance comparable to S.S.
9. The forces that are produced by TMA are 0.4 that of
s.s.
10. Spring back properties are not lost during the
bending operation.
11. TMA is ductile, which allows for placement of
tieback loops or complicated bends.

PG CANINE RETRACTION
SPRING

The design of original
spring
• It is made from 016x022 inch stainless steel wire.
• With predominant element OVOID DOUBLE HELIX
LOOP extending 10 mm apically.
• The smaller occlusal loop with 2 mm diameter,
incorporated to lower the levels of activation.
 Ani tip bend (Alpha) 15˚.
 Anchorage bend (Beta) 12˚ for II premolar, 30˚ for I
molar. www.indiandentalacademy.comwww.indiandentalacademy.com

TEST FOR MODIFIED PG
SPRING :
CONSTRUUCTION OF MODIFIED SPRING
 Acrylic Teeth (canine, II pre molar, I molar) mounted
on acrylic plates simulating I pre molar extraction case.
 018 slot brackets of canine, II pre molar, and I molar
are bonded on acrylic teeth PASSIVELY.

 Test spring inserted in canine bracket and tied and
inserted in I molar tube, in II pre molar region it is not
tied-to reduce friction.

 The apical loop of test springs are opened by 0.5 mm,
1 mm, 1.5 mm, 2 mm, 2.5 mm each spring is activated
corresponding to opening of loop,
DIAL CALIPERS has been used for this purpose.
 DONTRIX GAUGE has been used for activation.
 Test springs are inserted in the bracket in a passive
state without incorporating Alfa, Beta and anti rotation
bends to measure pure horizontal force.

 The 2 mm loop after activation by 2 mm showed
horizontal of 90 gm approximately with Dontrix gauge.
 The loop design with opening of apical loop 2mm has
been selected for modified spring.
 Horizontal activation can be done by activating the
spring until the legs of loop come together.

THE MODIFICATION OF SPRING
DESIGN :
THE APICAL LOOP MODIFICATION:
 The original spring contains double ovoid helix loop
apically with the purpose of increasing the flexibility of
spring.
 The modified spring which is made from TMA wire
which is more flexible than S.S. The need for double
loop is not necessary, a single ovoid helix loop apically
is constructed.

 With the same occlusal loop with diameter of 2 mm.
 The Alfa Beta and anti rotation bends are increased,
since TMA gives 0.4 of force as compare to S.S. all
bends are increased slightly more than double as
compare to original spring.

THE DESIGN OF MODIFIED PG
SPRING
• It is constructed from 016x 022 inch TMA wire.
• With predominant element OVOID SINGLE HELIX
LOOP extending10 mm apically.
• The smaller occlusal loop with 2 mm diameter.
 Anti tip bend (Alpha) 35˚.
 Anchorage bend (Beta) 30˚ for II pre molar, 75˚ for I
molar.
 Anti rotation bend 85˚.www.indiandentalacademy.comwww.indiandentalacademy.com

MODIFIED PG CANINE RETRACTION
SPRING

TEMPLATE USED FOR SPRING
FABRICATION

FUNDAMENTAL
BIOMECHANICS
The displacement of canine depends on the
relationship between the line of force and the center of
resistance (CR)

THE CR OF CANINE :
Shown to be located in the center of the root one third
of the distance from the alveolar crest to the apex.

FOR TRANSLATION OF CANINE :
Application of force through CR.

APPLICATION OF FORCE :
Through the bracket away from CR.
NET RESULT:
Distal tipping and rotation of the canine around CR.

TO PRODUCE TRANSLATION OF
CANINE :
o Anti tip couple
o Anti rotational couple

50
100100100
50
100
DIFFERENCES IN FORCE
DECAY :
STAINLESS
STEEL
T.M.A.

AIM OF THE STUDY
To compare efficacy of original PG canine
retraction, and modified spring :
1. To compare rate and amount of canine
retraction.
2. To compare canine tipping and rotation.
3. To compare anchorage loss.

CRITERIA FOR CASE
SELECTION
• MODERATE TO MAXIMUM ANCHORAGE CASES.
• C-I OR C-II MOLAR RELATION.
• I-BICUSPID EXTRACTION CASES.
WHICH REQUIRES INDIVIDUAL CANINE
RETRACTION.
Age selection :

TREATMENT MECHANICS :
 Retraction of canines was preceded by a short period
of upper or lower arch leveling to bring the canines to
proper occlusal level.
 The retraction was started at the same time on both
sides and at the same time after first premolar
extractions.
Pre adjusted edgewise system, 018 slot, ROTH
SYSTEM.

ACTIVATIONS :
RIGHT SIDE :
 Modified PG spring (TMA)
 Activated 2mm
LEFT SIDE :
 Original PG spring (TMA)
 Activated by two loops are separated by 1mm

ADVANTAGES OF MODIFIED PG
SPRING
 Reduced bulk,
 More comfortable for patient
 Ease of fabrication,
 No chair side time for fabrication,

 Increased rate and amount of canine
retraction,
 Decreased canine tipping and rotations,
 Easily adjustable,
 Less deformation and distortion,
 Properties are not lost during bending
and activations.

CASE
REPORTS

CASE-I

CASE-II

CASE-III

CONCLUSION

ACNOWLEDGEMENTS

Pg canine retraction spring

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