1
CANINE RETRACTION
IN PRE-ADJUSTED
EDGEWISE APPLIANCE
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continu...
2
Canine retraction is an integral part of
many orthodontic treatment procedures and
considerable emphasis has been placed...
3
When considering canine retraction a
thorough knowledge on the following is
required
The basic principles involved in to...
4
BASIC PRINCIPLES OF TOOTH MOVEMENT
CENTER OF RESISTANCE
That point on a tooth, where when
a force is applied, the tooth ...
5
FORCE – is the load applied to an object that will tend
to move it to a different position in space.
A :When the line of...
6
MOMENT TO FORCE RATIO –. the relationship
between the force and the counter balancing couple is
expressed as the moment ...
Moment to force ratios of 1:7 produces controlled
tipping.
M /F ratio is 8:10 –bodily movement of teeth occurs.
Ratios gre...
8
RETRACTION MECHANISM CAN BE
GENERALLY CLASSIFIED INTO 2 TYPES
FRICTION OR SLIDING MECHANICS
Sliding the brackets along t...
9
Classification based on extraction space closure
requirements- to achieve treatment objectives
Type A – 75% to 100% of e...
10
FRICTION MECHANICS
ADVANTAGES OF SLIDING MECHANICS:
Minimal wire-bending time
Sufficient space for activations
Patient ...
11
DISADVANTAGES
No established guidelines on amounts of force to
be used during space closure
Tendency for initial overac...
12
MECHANICS INVOLVED
To move a tooth bodily the force applied has to pass
through the center of resistance of the tooth. ...
13
The moment of force is created in 2 planes of space.
A. Crown rotation- One moment tends to rotate the
canine mesial ou...
As distal tipping of the crown takes place, the tooth slides
along the arch wire till binding occur between the arch wire ...
15
As the tooth uprights the moment decreases until
the wire no longer binds. Then the canine retracts
along the arch wire...
16
RETRACTION FORCE SYSTEMS AND
METHODS EMPLOYED IN SLIDING
MECHANICS
Elastomeric chains or power chains
Elastic module wi...
17
ELASTOMERIC CHAINS OR POWER CHAINS
Introduced in 1960’s for canine retraction,
diastema closure, rotation correction an...
18
ADVANTAGES
Inexpensive, easily applied without archwire
removal.
Independent of patient co-operation.
easy to apply wit...
19
Tooth movement, pH and temperature
changes, fluoride rinses, salivary enzymes
and masticatory forces have all been
asso...
20
TYPES
E chain are available in 3 configuration
Closed loop chain
Short filament chain
Long filament chain:-generally de...
21
ELASTIC MODULE WITH LIGATURE
This method popularized by Bennett and McLaughlin.
A single elastic module of the type use...
22
If the arches are properly leveled this light force
allows for effective retraction with minimal tipping of
teeth and m...
23
Alternate delivery systems have been found to be
disadvantageous to elastic module in the following
aspects.
a. Power c...
24
ELASTIC THREAD
Elastic thread is inserted under the arch wire in a figure
of 8 configuration from the canine to premola...
25
ADVANTAGES
Neat method.
More comfortable.
Bodily movement of the canine tooth is achieved.
Easier to replace inorder to...
26
INTRA OR INTERMAXILLARY ELASTTICS TO
KOBAYASHI LIGATURE
The Kobayashi ligatures are SS ligatures incorporating a
welded...
27
They are loosely tied to the canine bracket and can be
left as a hook pointing mesially or can be tied so that
the hook...
28
ADVANTAGES
Simple to put on.
Readily measurable constant light force to tip the canine
along the arch wire, in the rang...
29
CLOSED COIL SPRING
Coil springs were introduced in orthodontic as early as
1931.
The various materials that have been u...
30
ADVANTAGES OF NITI COIL SPRINGS
Shape memory and super elasticity.
Low modules of elasticity, moderately high strength,...
31
DIFFERENT WAYS OF USING COIL SPRINGS
Coil springs threaded on to the arch wire and compressed
between the canine bracke...
32
Advantages
Force applied is easily measured.
The long length of coil will transmit a relatively constant
force over a l...
33
Coil spring between soldered stop and canine
bracket
Small piece of wire soldered on either side to act as stop.
Genera...
34
Coil spring between incisor bracket and canine tooth
Coil spring is compressed between central incisor and
canine brack...
35
Advantages
Coil spring short and less irritating.
Easily activated by retying or tightening the tie back
ligature.
Disa...
36
Advantages
Coil spring can be removed any time without removing the
arch wire.
Forces can be measured.
Spring activated...
37
EXTRA ORAL TRACTION
The arms of the extra oral traction are bent
into a small open circle (J hook) and hooked
directly ...
38
Advantages
Extremely conservative of anchorage.
Additional molar support by headgear
may be done.
Simultaneous overjet ...
39
Disadvantages
As force application is intermittent this is slower than othe
method of canine retraction.
Highly depende...
40
SLIDING JIG AND TRACTION
In this a jig is made in 0.022” round wire or 0.017
x 0.022” rectangular wire and slide on to ...
41
Advantages
Force exerted by the elastics is directed along the
arch wire and thus bodily movement of canine is
possible...
42
Mulligan’s V Bend sliding mechanics
Introduced by Mulligan in 1970’s.
The basic principle was to apply differential mom...
43
The wire is tied in 4 – 6 weeks for alignment then 45° V
Bend are added and 200gms of force is applied between
canine a...
44
Mandibular canine retraction
with V-bend sliding mechanics
www.indiandentalacademy.com
45
USE OF TIP EDGE BRACKETS ON CANINES
Tip edge brackets used in cases of an upright or
distally tipped canine as the arch...
46
FRICTIONLESS MECHANICS :-
( DISTAL MOVEMENT OF THE CANINE WITH
THE ARCH WIRE ) .
-Involves use of closing loops fabrica...
47
Bio Mechanics :
In Frictionless mechanics tooth movement is achieved
not by sliding the brackets through the wire but b...
48
- A simple loop when activated is unable to generateA simple loop when activated is unable to generate
adequate counter...
49
. When the springs are used two moments control
anchorage and vertical forces
The α moment produces distal of an of ant...
50
A: Beta moment greater than
alpha moment producing net
intrusive force on the anterior
teeth and extrusive force on
pos...
51
The distance that the anterior and posterior segment
are to be moved depends on factor such as
- Amount of crowding
- A...
52
a. For anterior retraction
- Loop placed closer to canine than molar
↓
- Gable bend added near the molar
↓
- Gable bend...
53
c. For both anterior retraction and posterior
protraction loop placed midway between anterior and
posterior segment.
↓
...
54
As anterior teeth are retracted the magnitude of α
moment decreases faster than β.
↓
Enhancing posterior anchorage. Als...
55
Constancy of Force and Moments
Optimal biologic responses not only, depends on the
initial force magnitude but also on ...
56
The design of the spring influences not only the M/F
ratio but also load deflection rate the addition of
helices lowers...
57
CRITERIA FOR AN IDEAL CANINE RETRACTION
SPRING
Should promote translation sagittaly and horizontally
through an anti ti...
58
ADVANTAGES OF FRICTIONLESS MECHANICS
Predetermined force systems can be exerted - within
the control of the orthodontis...
59
DISADVANTAGES OF FRICTION LESS
MECHANICS
Extra wire bending & chair side time
Good understanding of biomechanics necess...
60
RICKETTS RETRACTION SPRING
Maxillary cuspid retraction spring
Is a double vertical helical extended crossed T closing
l...
61
Mandibular cuspid spring
Is a compound spring with a double vertical
helical closing loop.
Contains 60mm of wire .
Made...
62
PG RETRACTION SPRING
Described by Poul Gjessing.
The spring consists of a double ovoid helix with a smaller
occlusally ...
63
The gentle rounded form avoids the effects of sharp
bends on load deflection.
- The use of large amount of wire in the ...
64
The distal driving force is generated by pulling the distal,
horizontal leg through the molar tube.
A desirable force l...
65
C
PG Universal Retraction Spring can be adjusted for canine
retraction (A), uprighting of canine (B) or incisor Retract...
66
BURSTONE T LOOP RETRACTION SPRING
Made of 0.017 x 0.025 TMA in an 0.022 slot
0.016 x 0.022 TMA in an 0.018 slot
Designe...
67
Engaged into auxiliary tube of first molar and the
vertical tube on the Burstone’s canine bracket
The magnitude of forc...
68
Initially M/F ratio is 6 – 8:1 which produce controlled
tipping. As space close and spring deactivates the force
level ...
69
Used for canine retraction / incisor retraction /
segmental en masse retraction
Differential anchorage obtained by appl...
70
NEW METHODS OF CANINE RETRACTION
Retraction Using rare earth magnets
Distraction of the periodontal ligament
- Liou et ...
711.1. Deepening of extraction socket
Occlusal view
Buccal view
DISTRACTION OF THE PERIODONTAL LIGAMENT
SURGICAL PROCEDURE...
72
2.2. Thinning interseptal
bone
3. Undermining
interseptal bone
(buccal, lingual,
& bottom grooving)
www.indiandentalaca...
73
Canine distraction device is
placed close to center of
resistance to achieve bodily
movement
www.indiandentalacademy.com
74
Liou and Huang (1998) stated that the process of
osteogenesis in the periodontal ligament during orthodontic
tooth move...
75
Both the upper and lower canines were distracted 6.5
mm into the extraction space within 3 weeks.
New alveolar bone was...
76
The radiographic examination revealed that apical and
lateral surface root resorption of the canines was minimal.
They ...
77
USE OF RARE EARTH MAGNETS
When two magnets are in
repulsion (A) or attraction
(B), resulting force is
hyperbolic curve....
78
Constant force delivery system . A: rare earth block
magnets; B: vestibular wire; L: "corner-braces" to
increase stiffn...
79
REFERENCES
1- JCO 1991 Jun (364-369): Clinical Considerations
Use of Retraction Mechanics - JULIE ANN
STAGGERS, DDS, MS...
80
REFERENCES contd…
6:- AJO –1996 VOL MAY (489-495) Canine retraction
with rare earth magnets: An investigation into the
...
81
THANK YOU
For more details please visit
www.indiandentalacademy.com
www.indiandentalacademy.com
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Canine retraction in pre adjusted edgewise technique /certified fixed orthodontic courses by Indian dental academy

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Canine retraction in pre adjusted edgewise technique /certified fixed orthodontic courses by Indian dental academy

  1. 1. 1 CANINE RETRACTION IN PRE-ADJUSTED EDGEWISE APPLIANCE www.indiandentalacademy.com INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
  2. 2. 2 Canine retraction is an integral part of many orthodontic treatment procedures and considerable emphasis has been placed on those mechanisms which are used to accomplish it. Some of these mechanisms move the canine distally in a bodily manner, others tip the canine, necessitating a subsequent uprighting phase. Most of them incorporate some mechanisms to avoid the undesirable distolingual rotation as the canines are moved distally. INTRODUCTION www.indiandentalacademy.com
  3. 3. 3 When considering canine retraction a thorough knowledge on the following is required The basic principles involved in tooth movement The type of anchorage required for that particular patient The types of retraction mechanics The force systems available for each type of retraction mechanics. Clinical considerations www.indiandentalacademy.com
  4. 4. 4 BASIC PRINCIPLES OF TOOTH MOVEMENT CENTER OF RESISTANCE That point on a tooth, where when a force is applied, the tooth translates or moves bodily & all points on the tooth move in the same direction together. CENTER OF ROTATION That point around which the tooth rotates when force is applied. www.indiandentalacademy.com
  5. 5. 5 FORCE – is the load applied to an object that will tend to move it to a different position in space. A :When the line of force passes through the center of resistance bodily movement of teeth occurs B. When the line of force does not pass through the center of resistance, a moment is produced and rotation occurs. MOMENT – is the force acting at a distance. Is defined as the product of force times the perpendicular distance from the center of resistance. www.indiandentalacademy.com
  6. 6. 6 MOMENT TO FORCE RATIO –. the relationship between the force and the counter balancing couple is expressed as the moment to force ratio. It determines the type of tooth movement. The rotating tendency induced by a single force at the bracket, will continue to tip the tooth unless a counter moment or counter – rotating tendency is applied at the bracket to achieve the desired type of tooth movement This counter moment or secondary moment is applied at the bracket by the wire or a ‘V’ bend – and should be equal in magnitude but opposite in direction to the initial moment to achieve bodily movement www.indiandentalacademy.com
  7. 7. Moment to force ratios of 1:7 produces controlled tipping. M /F ratio is 8:10 –bodily movement of teeth occurs. Ratios greater than 10 produce torque. COUPLE -Is two parallel forces of equal magnitude acting in opposite directions . Rotations are also achieved with moments of couple. 7www.indiandentalacademy.com
  8. 8. 8 RETRACTION MECHANISM CAN BE GENERALLY CLASSIFIED INTO 2 TYPES FRICTION OR SLIDING MECHANICS Sliding the brackets along the arch wire OR sliding the arch wire through bracket and tubes Friction occurs at the bracket – wire interface, affects force levels, higher force is required to overcome friction and to exert optimum force for tooth movement FRICTIONLESS MECHANICS Distal movement of the canine with the arch wire. closing loop‘s which was activated in the office by opening the closing loop and moving the arch wire through the posterior bracket slots www.indiandentalacademy.com
  9. 9. 9 Classification based on extraction space closure requirements- to achieve treatment objectives Type A – 75% to 100% of extraction space closure is achieved by retraction of ANTERIORS Type B – Almost equal amount of movement of ANTERIORS and POSTERIORS towards each other Type C – 75% to 100% of extraction space closure by mesial movement of POSTERIORS ANCHORAGE CONSIDERATION www.indiandentalacademy.com
  10. 10. 10 FRICTION MECHANICS ADVANTAGES OF SLIDING MECHANICS: Minimal wire-bending time Sufficient space for activations Patient comfort Less time consumption for placement The most significant difference between the mechanics of standard edgewise and the preadjusted edgewise appliance was seen during space closure.Level bracket slot arrangement and the absence of bends in the arch wire allowed the use of friction mechanics. www.indiandentalacademy.com
  11. 11. 11 DISADVANTAGES No established guidelines on amounts of force to be used during space closure Tendency for initial overactivation of elastic and spring forces, causing initial tipping and inadequate rebound time for uprighting Generally slower than loop mechanics due to presence of friction. Force degradation of elastics and springs. www.indiandentalacademy.com
  12. 12. 12 MECHANICS INVOLVED To move a tooth bodily the force applied has to pass through the center of resistance of the tooth. However as the force is applied at the bracket level of the crown, the concerned tooth experiences both force and moment. Moments of force produced by elastic chain placed at bracket level and not at center of resistance. www.indiandentalacademy.com
  13. 13. 13 The moment of force is created in 2 planes of space. A. Crown rotation- One moment tends to rotate the canine mesial out as force application is buccal to the centre of rotation B. Crown tipping- Second moment tends to cause distal tipping of tooth as the point of force appliance is occlusal to centre of resistance. The wire bracket interaction tends to counteract this moment by applying an opposite moment.www.indiandentalacademy.com
  14. 14. As distal tipping of the crown takes place, the tooth slides along the arch wire till binding occur between the arch wire and the bracket. This produces a couple at the bracket which results in distal root movement and hence uprighting of the tooth. The wire deflects to produce a couple which uprights the tooth. 14www.indiandentalacademy.com
  15. 15. 15 As the tooth uprights the moment decreases until the wire no longer binds. Then the canine retracts along the arch wire till distal crown tipping again causes binding. This process is repeated until the tooth is retracted or the force gets depleted.This initial tipping of crown followed by root uprighting is called walking of canine. The magnitude of the root uprighting depends on the size, shape and material of the wire and the width of the bracket. The larger the load deflection rate of the wire, the greater the force from its deflection and hence greater the moment produced. - The wider the bracket, the larger is the moment arm and hence greater is the moment. www.indiandentalacademy.com
  16. 16. 16 RETRACTION FORCE SYSTEMS AND METHODS EMPLOYED IN SLIDING MECHANICS Elastomeric chains or power chains Elastic module with ligature (Bennett's method) Elastic thread. Elastic bands hooked over prefabrication ligature hook. Coil springs J Hook Head Gear Sliding jig and traction. Mulligan’s V Bend sliding mechanics. Employing tip edge brackets on canines. www.indiandentalacademy.com
  17. 17. 17 ELASTOMERIC CHAINS OR POWER CHAINS Introduced in 1960’s for canine retraction, diastema closure, rotation correction and arch construction. Engaged by stretching 50-70% of its length to give varied force levels as required 50-70% of force is lost in first 24 hours, at 3 weeks only 30% remains, pre-stretching has been suggested, but only 5% gain in force value Wide variation in force level, prudent to use a force gauge to determine desired initial force level www.indiandentalacademy.com
  18. 18. 18 ADVANTAGES Inexpensive, easily applied without archwire removal. Independent of patient co-operation. easy to apply without removing arch wire DISADVANTAGES Absorbs water & saliva, staining. Break down of internal bonds, permanent deformation causing rapid loss of force. Stress relocation leads to loss of force and hence gradual loss of effectiveness.www.indiandentalacademy.com
  19. 19. 19 Tooth movement, pH and temperature changes, fluoride rinses, salivary enzymes and masticatory forces have all been associated with deformation, force degradation and relaxation behaviour of Elastomeric chains. 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. www.indiandentalacademy.com
  20. 20. 20 TYPES E chain are available in 3 configuration Closed loop chain Short filament chain Long filament chain:-generally deliver a lower initial force and exhibit a greater rate of force decay at the same extension. www.indiandentalacademy.com
  21. 21. 21 ELASTIC MODULE WITH LIGATURE This method popularized by Bennett and McLaughlin. A single elastic module of the type used to secure arch wires to brackets is attached to the canine by ligature wire extending from the molar. These elastic tie backs are activated 2-3mm or to twice then original size to generate approximately 100 – 150 gms of force. www.indiandentalacademy.com
  22. 22. 22 If the arches are properly leveled this light force allows for effective retraction with minimal tipping of teeth and maintenance of arch leveling. Bennett recommended 0.019 x 0.025” rectangular wire in 0.022” slot to be most effective, providing maximum rigidity while allowing adequate freedom for sliding Retraction rate of 1mm/month. www.indiandentalacademy.com
  23. 23. 23 Alternate delivery systems have been found to be disadvantageous to elastic module in the following aspects. a. Power chains – gives variable force - difficult to keep clean - may falls off b. Elastics - Require patient compliance. c. SS coil springs - Deliver excess force and - Unhygienic www.indiandentalacademy.com
  24. 24. 24 ELASTIC THREAD Elastic thread is inserted under the arch wire in a figure of 8 configuration from the canine to premolar and firmly knotted. The premolar is firmly / tightly ligated to the molar by a stainless steel ligature wire. Elastic thread is obtainable in two different forms 1: Cotton covered:- Is easier to knot firmly but becomes dirty in use. 2 : Plain uncovered elastic :-Remains clean in mouth but with passage of time can loosen. The sizes available are 0.625mm (0.025”) and 0.75mm (0.030”). www.indiandentalacademy.com
  25. 25. 25 ADVANTAGES Neat method. More comfortable. Bodily movement of the canine tooth is achieved. Easier to replace inorder to reactivate at each visit without removing the arch wire. DISADVANTAGES Thread is wasted in tying the Knot. The knot will untie unless it is pulled very tight. Knot causes irritations to the cheek if it is not carefully tucked out of the way. Difficult to regulate the forces. This technique not recommended for use when the canine can be engaged only by a thin arch wire.www.indiandentalacademy.com
  26. 26. 26 INTRA OR INTERMAXILLARY ELASTTICS TO KOBAYASHI LIGATURE The Kobayashi ligatures are SS ligatures incorporating a welded hook for intra or intermaxillary elastics. www.indiandentalacademy.com
  27. 27. 27 They are loosely tied to the canine bracket and can be left as a hook pointing mesially or can be tied so that the hook faces distally and is then bent forward. It is a useful method of applying light forces to tip the canine distally along a thin flexible arch wire. It is not a good method of applying traction to an already upright canine which requires further retraction by bodily movement. www.indiandentalacademy.com
  28. 28. 28 ADVANTAGES Simple to put on. Readily measurable constant light force to tip the canine along the arch wire, in the range of 40 – 100gms. Can be applied by the patient hooking the elastic bands over the ligatures. DISADVANTAGES Not an effective method of applying traction to slide the canine bodily along the arch wire because the strong elastics required for bodily movement cause rotation and excessive bending of the canine. Relies on patients compliance in wearing elastics and wearing them correctly. www.indiandentalacademy.com
  29. 29. 29 CLOSED COIL SPRING Coil springs were introduced in orthodontic as early as 1931. The various materials that have been used for making springs are :- Stainless steel, Niti , Co – Cr - Ni Alloy www.indiandentalacademy.com
  30. 30. 30 ADVANTAGES OF NITI COIL SPRINGS Shape memory and super elasticity. Low modules of elasticity, moderately high strength, high resilience and low corrosion. Deliver constant amount of form till they reach the terminal end of deactivation stage. Produce constant force over a wide range of activation and generally close space with single activation. Can be easily placed and removed without arch wire removal. Do not need to be reactivated at each appointment. A cooperation not required. DISADVANTAGES OF NITI SPRINGS Relatively unhygienic compared to elastic force systems. www.indiandentalacademy.com
  31. 31. 31 DIFFERENT WAYS OF USING COIL SPRINGS Coil springs threaded on to the arch wire and compressed between the canine brackets. Coil spring compressed between a soldered stop on the arch wire and canine bracket. Compressed between an incisor bracket and the canine. Compressed by a tie back ligature. Expanded tied back coil spring. Coil spring compressed between canine brackets Coil spring measured 3/4th of distance canine pulled twice its length and compressed. The arch wire should closely fit the bracket slot, and cinches distal to molar.www.indiandentalacademy.com
  32. 32. 32 Advantages Force applied is easily measured. The long length of coil will transmit a relatively constant force over a long distance. Requires little reactivation. Disadvantages Increase in intercanine width as the coil spring on the anterior curvature of the arch wire exerts a lateral as well as distal component of force. Length of coil spring can be irritating to the patients lip. www.indiandentalacademy.com
  33. 33. 33 Coil spring between soldered stop and canine bracket Small piece of wire soldered on either side to act as stop. Generally placed at distal margin of lateral incisor. Two length of closed coil springs, a little more than half of the distance of stop and canine are selected and then compressed. The arch wire should closely fill the slot. Advantages Less irritating to the patient than long continuous coil. Neat Forces applied are easily measured. Disadvantages Annealing of the wire during soldering. Increase in intercanine width may occur. Spring required reactivation more frequently. To reactivate a compressed coil spring 2mm length of www.indiandentalacademy.com
  34. 34. 34 Coil spring between incisor bracket and canine tooth Coil spring is compressed between central incisor and canine bracket. Excellent method of closing upper incisor spaces / central diastema, using the force exerted by the reciprocal action of the coil spring. Coil springs compressed by a tie back ligature Two 3 – 4mm length of closed coil spring opened to twice their length then recompressed are threaded to the arch wire to lie mesial to the canines. Using soft SS ligature is placed mesial to springs twisted and tied to premolars. Arch wire should be rigid and should fill the slot.www.indiandentalacademy.com
  35. 35. 35 Advantages Coil spring short and less irritating. Easily activated by retying or tightening the tie back ligature. Disadvantages Long ligature likely to be damaged. Tied back expanded coil spring This technique uses a coil spring is opened on activating pulling the canine distally rather than pushing it as the compressed spring does. Can be used to tilt back a mesially inclined canine along a thin flexible arch wire or can be used to bodily retract the causes sliding it along a right arch wire.www.indiandentalacademy.com
  36. 36. 36 Advantages Coil spring can be removed any time without removing the arch wire. Forces can be measured. Spring activated by simply tightening the ligature. Intercanine width is not increased as coils lies behind the canine. Disadvantages Susceptible to damage. Ligature can fracture. Spring tends to act as food trap. www.indiandentalacademy.com
  37. 37. 37 EXTRA ORAL TRACTION The arms of the extra oral traction are bent into a small open circle (J hook) and hooked directly on to the arch wire to contact mesial of the canine bracket. The direction of the pull should be as near as possible along the occlusal plane, this usually requires a straight pull headgear for both maxillary and mandibular canine. However, when this technique is used to retract all four canines together a high pull head gear is used for the maxillary canine and a straight pull for the mandibular canine. www.indiandentalacademy.com
  38. 38. 38 Advantages Extremely conservative of anchorage. Additional molar support by headgear may be done. Simultaneous overjet reduction might occur during canine retraction due to the distal force and binding of the archwire. Can be applied to both upper and lower arches simultaneously (use of Hickham’s headgear system) www.indiandentalacademy.com
  39. 39. 39 Disadvantages As force application is intermittent this is slower than othe method of canine retraction. Highly dependent on patients cooperation. Canine tipping and anterior extrusion may occur with straight pull headgear. Soreness of the corner of mouth from side piece arm can occur. The molar and buccal segment correction is usually a later event in treatment compared to other system. Mesio buccal rotation of canine. Flaring of canine into buccal cortex. One canine may retract faster than the other (this may be due to patient hooking the traction arm on to the same side first). www.indiandentalacademy.com
  40. 40. 40 SLIDING JIG AND TRACTION In this a jig is made in 0.022” round wire or 0.017 x 0.022” rectangular wire and slide on to the arch wire is addition to a short piece of open coil spring of about 4mm in length. The coil spring lies in contact with mesial end of canine bracket and circle of jig lies on the mesial end of coil spring. The traction can be applied to the jig by either intra or inter maxillary elastics or by extra oral traction www.indiandentalacademy.com
  41. 41. 41 Advantages Force exerted by the elastics is directed along the arch wire and thus bodily movement of canine is possible. In cases of extraoral traction method, the jig brings forward the point of application of J hooks thus reducing the soreness at corner of mouth. Disadvantages Difficult to fabricate Food entrapment Can dislodge the brackets Irritation to cheek. www.indiandentalacademy.com
  42. 42. 42 Mulligan’s V Bend sliding mechanics Introduced by Mulligan in 1970’s. The basic principle was to apply differential moments to the teeth via bends in the continuous arch wire while force for retraction was applied by auxiliaries like E chain, coil spring etc. In 0.018” slot 0.016 SS wire , 0.022” slot 0.016 , 0.018, 0.020 SS wires used for retraction. The arch wire is not tied in the incisor bracket during cuspid retraction, as this reduces a. Distal root moment placed in cause b. Causes incisors flaring c. Causes severe mesial root movement of canine. www.indiandentalacademy.com
  43. 43. 43 The wire is tied in 4 – 6 weeks for alignment then 45° V Bend are added and 200gms of force is applied between canine and molar. The purpose of V Bend is to allow differential mesio distal moments on canine and molars. - If the bend is off centered it creates a short and long segment. The short segment is more rigid and hence applied greater moment, so if maximal canine retraction is required the bend is placed close to molars and bicuspids not banded. - This causes strong distal crown moment on molar which counteracts the auxiliary force tending to move molar crown forward – Reinforcing anchorage.www.indiandentalacademy.com
  44. 44. 44 Mandibular canine retraction with V-bend sliding mechanics www.indiandentalacademy.com
  45. 45. 45 USE OF TIP EDGE BRACKETS ON CANINES Tip edge brackets used in cases of an upright or distally tipped canine as the arch wire insertion can causes bite deepening due to incisor extrusion. This eliminates binding between wire and slot during initial stages when major movements are accomplished. As retraction is complete uprighting springs may be used to correct canine angulation without causing anterior extrusion. Full size rectangular wire can then be placed for achieve desired tip / torque specifications. www.indiandentalacademy.com
  46. 46. 46 FRICTIONLESS MECHANICS :- ( DISTAL MOVEMENT OF THE CANINE WITH THE ARCH WIRE ) . -Involves use of closing loops fabricated in either full or sectional arch wires to induce tooth movement -Designed to provide low load – deflection rate (force per unit deactivation) and controlled M/F ratios -Precise application of force systems giving three dimensional control over tooth movement. www.indiandentalacademy.com
  47. 47. 47 Bio Mechanics : In Frictionless mechanics tooth movement is achieved not by sliding the brackets through the wire but by the activation of loops with specific bends ( pre-activation bends - Alpha and Beta ) to achieve desired type of tooth movement Force is applied by pulling the arms of the loops away and cinching them back at the molar tubes Anterior bend or ALPHA bend - alpha moment Posterior bend - BETA bend -beta momentBetaBeta AlphaAlpha www.indiandentalacademy.com
  48. 48. 48 - A simple loop when activated is unable to generateA simple loop when activated is unable to generate adequate counter moment required to achieve theadequate counter moment required to achieve the desired tooth movementdesired tooth movement - So , pre-activation bends are given - increases M/FSo , pre-activation bends are given - increases M/F ratioratio - They are placed within the loop or where the loop meetsThey are placed within the loop or where the loop meets the wirethe wire www.indiandentalacademy.com
  49. 49. 49 . When the springs are used two moments control anchorage and vertical forces The α moment produces distal of an of anterior teeth while the β moment causes mesial root movement of the posterior teeth by varying the magnitude of these moments differential movement of posterior and anterior segment can be achieved. If the moments are equal - no vertical forces are exerted However if α and β moments are unequal vertical forces are also generated. www.indiandentalacademy.com
  50. 50. 50 A: Beta moment greater than alpha moment producing net intrusive force on the anterior teeth and extrusive force on posterior teeth. B: Alpha moment greater than beta moment producing net intrusive force on posterior teeth and extrusive force on anterior teeth. C:Equal alpha and beta moments,producing no vertical component of force. www.indiandentalacademy.com
  51. 51. 51 The distance that the anterior and posterior segment are to be moved depends on factor such as - Amount of crowding - Anchorage - Axial inclination of canines an incisors. - Midline discrepancy any and right / left symmetry. - Vertical dimension The amount of anterior retraction or posterior protraction needed should be determined before a loop is designed. www.indiandentalacademy.com
  52. 52. 52 a. For anterior retraction - Loop placed closer to canine than molar ↓ - Gable bend added near the molar ↓ - Gable bend larger in posterior dimension produce a large β moment and thus increases posterior anchorage. b. For posterior protraction – - Loop located closer to the posterior segment. ↓ - Anterior Gable bend placed. ↓ Gable Bend has large α moment than β thus making anterior segment as anchorage. www.indiandentalacademy.com
  53. 53. 53 c. For both anterior retraction and posterior protraction loop placed midway between anterior and posterior segment. ↓ Gable bend at equal dimension used ↓ Equal α and β moment generated ↓ Reciprocal space closure occur Regardless of the initial magnitudes of both α and β moment, changes will occur during retraction. www.indiandentalacademy.com
  54. 54. 54 As anterior teeth are retracted the magnitude of α moment decreases faster than β. ↓ Enhancing posterior anchorage. Also as β moment becomes relatively greater. ↓ Greater intrusive force on anterior teeth and greater extrusive force on posterior teeth. Concurrent with the decrease in both α and β moment there is increase in M/F ratio thus producing a pure translation. www.indiandentalacademy.com
  55. 55. 55 Constancy of Force and Moments Optimal biologic responses not only, depends on the initial force magnitude but also on the rate of decay of force taking place between activation. According to Burstone the M/F ratio can be increased by Increasing vertical dimension gingival to the bracket. Increasing the horizontal dimension in the apical part of the loop. Decreasing the inter bracket distance. Positioning the loop close to the tooth to be retracted. Angulating the mesial and distal legs of the spring Adding more wire gingival to the bracket.www.indiandentalacademy.com
  56. 56. 56 The design of the spring influences not only the M/F ratio but also load deflection rate the addition of helices lowers the load deflection rate. It can be changed by changing the wire composition. TMA (Titanium Molybdenum Alloy) decreases load deflection rate when compared to stainless steel. Types of cuspid retraction springs Ricketts maxillary and mandibular cuspid retraction spring. PG (Poul Gjessing) canine retraction spring Burstone T loop retraction spring. Vertical loops, L-loop, helical loops - nickel titanium canine retraction spring. www.indiandentalacademy.com
  57. 57. 57 CRITERIA FOR AN IDEAL CANINE RETRACTION SPRING Should promote translation sagittaly and horizontally through an anti tip M/F ratio of 11:1 and an anti rotation M/F ratio of 4:1. Result in low load deflection ratio during generation of retraction force in the range of 50 – 200 gms. Result in no adverse interaction between anti tip and anti rotation moments during activation. Should be possible to use it in both 0.018 and 0.022 inch slot. Have limited dimension and allow for faciolingual adjustments. www.indiandentalacademy.com
  58. 58. 58 ADVANTAGES OF FRICTIONLESS MECHANICS Predetermined force systems can be exerted - within the control of the orthodontist No role of friction - optimum force levels accurately achieved, less tax on anchorage Desired type of tooth movement can be achieved by control over M/F ratios by altering design , bends or positions of the springs www.indiandentalacademy.com
  59. 59. 59 DISADVANTAGES OF FRICTION LESS MECHANICS Extra wire bending & chair side time Good understanding of biomechanics necessary Undesirable movement of teeth easily possible if not monitored properly Appliance distortion intraorally affects application of predetermined force systems Uncomfortable to some patients. www.indiandentalacademy.com
  60. 60. 60 RICKETTS RETRACTION SPRING Maxillary cuspid retraction spring Is a double vertical helical extended crossed T closing loops spring which contains 70mm of wire. It produce 50 gm per mm of activation Because of additional wire used in its design and all loops are being contracted during its activation. 3 – 4 mm of activation are sufficient for upper cuspid retraction. www.indiandentalacademy.com
  61. 61. 61 Mandibular cuspid spring Is a compound spring with a double vertical helical closing loop. Contains 60mm of wire . Made of 16 x 16 blue elgiloy. Produces 75gm of force / mm of activation. 2-3mm of activation is required to produce the desired force. www.indiandentalacademy.com
  62. 62. 62 PG RETRACTION SPRING Described by Poul Gjessing. The spring consists of a double ovoid helix with a smaller occlusally placed helix. Available commercially in the preformed version, constructed in 0.016 x 0.022” SS. The predominant active element is the ovoid double helix loop extending 10mm apically. It is included in order to reduce the load deflection of the spring and is placed gingivally so that activation will cause a tipping of short arm (attached to the canine) in a direction that will increase the couple acting on the tooth. www.indiandentalacademy.com
  63. 63. 63 The gentle rounded form avoids the effects of sharp bends on load deflection. - The use of large amount of wire in the vertical dimension leads to maximum reduction of load deflection. - Minimizing horizontal wire increases rigidity in the vertical plane. Smaller occlusal loop serves to - Lower the level of activation on insertion. - Is formed so that activation further closes the loop. www.indiandentalacademy.com
  64. 64. 64 The distal driving force is generated by pulling the distal, horizontal leg through the molar tube. A desirable force level of approximately 160 gms is obtained when two section of double helix are separated by 1mm. The PG universal retraction spring is designed for controlled retraction of either canine or upper incisor. The spring is precalibrated to deliver predictable M/F ratio in 3 planes of space. Bracket engagement Activated spring www.indiandentalacademy.com
  65. 65. 65 C PG Universal Retraction Spring can be adjusted for canine retraction (A), uprighting of canine (B) or incisor Retraction (C) B A www.indiandentalacademy.com
  66. 66. 66 BURSTONE T LOOP RETRACTION SPRING Made of 0.017 x 0.025 TMA in an 0.022 slot 0.016 x 0.022 TMA in an 0.018 slot Designed for Enmasse or separate incisor and canine retraction in segmented arch technique. The basic element of the spring is prefabricated highly standardized universal springs which could be used on both right and left sides. These prefabricated versions have to be preactivated as per a prescribed template. www.indiandentalacademy.com
  67. 67. 67 Engaged into auxiliary tube of first molar and the vertical tube on the Burstone’s canine bracket The magnitude of force delivered is identified by reading the horizontal separation of the vertical legs of the T loop. www.indiandentalacademy.com
  68. 68. 68 Initially M/F ratio is 6 – 8:1 which produce controlled tipping. As space close and spring deactivates the force level decrease and M/F ratio in both alpha and beta arm to increase, so that the M/F ratio is 10:1 and translations occurs. Further deactivation increase M/F ratio to 12:1 and root movement occurs. Therefore, it is important that this spring is not reactivated too soon. If reactivated too frequently the teeth would undergo only tipping. The T loop is available in 2 heights a. Regular / long height b. Short height Activation is 3 – 4 mm.www.indiandentalacademy.com
  69. 69. 69 Used for canine retraction / incisor retraction / segmental en masse retraction Differential anchorage obtained by application of unequal alpha and beta moments. In group A anchorage cases, higher moment is applied to anchor teeth, T loop positioned closer to posterior segment In group B anchorage cases equal and opposite moments and forces applied for symmetric space closure, T loop positioned at the center In group C anchorage cases, T loop is positioned near the anterior segment – care is taken to prevent possible extrusion of anteriorswww.indiandentalacademy.com
  70. 70. 70 NEW METHODS OF CANINE RETRACTION Retraction Using rare earth magnets Distraction of the periodontal ligament - Liou et al (1998) proposed a new concept – ‘dental distraction’ - 6.5mm of canine retraction in 3 weeks - Less than 0.5 mm anchor loss - Tooth borne, custom made intra oral distraction device Dentoalveolar distraction osteogenesis for rapid orthodontic canine retraction. www.indiandentalacademy.com
  71. 71. 711.1. Deepening of extraction socket Occlusal view Buccal view DISTRACTION OF THE PERIODONTAL LIGAMENT SURGICAL PROCEDURE www.indiandentalacademy.com
  72. 72. 72 2.2. Thinning interseptal bone 3. Undermining interseptal bone (buccal, lingual, & bottom grooving) www.indiandentalacademy.com
  73. 73. 73 Canine distraction device is placed close to center of resistance to achieve bodily movement www.indiandentalacademy.com
  74. 74. 74 Liou and Huang (1998) stated that the process of osteogenesis in the periodontal ligament during orthodontic tooth movement is similar to the osteogenesis in the midpalatal suture during rapid palatal expansion. They proposed a new concept of ‘distracting the periodontal ligament’ to elicit rapid canine retraction in 3 weeks. They coined the term ‘dental distraction’ for this procedure. At the time of first premolar extraction, the interseptal bone distal to the canine was undermined with a bone bur, grooving vertically inside the extraction socket along the buccal and lingual sides and extending obliquely towards the socket base. Then a tooth borne, custom made intraoral distraction device was placed to retract the canines into the extraction space. The anchor units were the second premolar and first molar. www.indiandentalacademy.com
  75. 75. 75 Both the upper and lower canines were distracted 6.5 mm into the extraction space within 3 weeks. New alveolar bone was generated land remodelled rapidly in the mesial periodontal ligament of the canines during and after distraction. It becomes indistinguishable from the native alveolar bone 3 months after distraction. During the distraction, 73% of the first molars did not move mesially and 27% of them moved mesially less than 0.5mm within 3 weeks. www.indiandentalacademy.com
  76. 76. 76 The radiographic examination revealed that apical and lateral surface root resorption of the canines was minimal. They concluded that the periodontal ligament could be distracted to elicit rapid canine retraction without complications. This innovative approach can significantly reduce orthodontic treatment time and merits further investigation. www.indiandentalacademy.com
  77. 77. 77 USE OF RARE EARTH MAGNETS When two magnets are in repulsion (A) or attraction (B), resulting force is hyperbolic curve. Its magnitude is roughly inversely proportional to square of airgap between two magnets (Coulomb's law). However, when three magnets are combined so that two poles are in attraction and two in repulsion (C), there is certain range of activation for which force magnitude remains practically unchanged . www.indiandentalacademy.com
  78. 78. 78 Constant force delivery system . A: rare earth block magnets; B: vestibular wire; L: "corner-braces" to increase stiffness; S: helix that allows middle magnet to slide on vestibular wire . This system did not require reactivation, as loop was kept open by the magnetic force for entire experimental period. Prolonged constant force provides more effective tooth movement than an impulsive force of short duration. DISAVANTAGE- Expensive www.indiandentalacademy.com
  79. 79. 79 REFERENCES 1- JCO 1991 Jun (364-369): Clinical Considerations Use of Retraction Mechanics - JULIE ANN STAGGERS, DDS, MS, NICHOLAS GERMANE, DMD, MS 2:- JCO 1994 Sep (539-546): Force System Analysis of V-Bend Sliding Mechanics - RAYMOND E. SIATKOWSKI, DMD 3:- JCO 1992 Mar (165-178): The Tip-Edge Concept: Eliminating Unnecessary Anchorage Strain - CHRISTOPHER K. KESLING, DDS, MS 4:- JCO 1994 May (293-295): Comparison of NiTi Coil Springs vs. Elastics in Canine Retraction - ANDREW L. SONIS, DMD 5:- JCO 1987 Dec (857-870): Bioprogressive Simplified Part 4 - Extraction Therapy - JAMES J. HILGERS, DDS, MS www.indiandentalacademy.com
  80. 80. 80 REFERENCES contd… 6:- AJO –1996 VOL MAY (489-495) Canine retraction with rare earth magnets: An investigation into the validity of the constant force hypothesis-John Daskalogiannakis, DDS, MSc, and Kenneth Roy McLachlan, PhD-Toronto, Ontario, and Winnipeg, Manitoba, Canada. 7:- Textbook on biomechanics in clinical orthodontics- by-Dr.ravindra nanda 8:- JCO 1990 Nov (678-683): Vertical Force Considerations in Differential Space Closure - BIRTE MELSEN, DO, VASSILI FOTIS, DDS, MSD, CHARLES J. BURSTONE, D www.indiandentalacademy.com
  81. 81. 81 THANK YOU For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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