MBT philosophy and guidelines

1. MBT
Presented by :
Dr. Siddharth Konwar

2. CONTENTS :
• Introduction
• Review of literature
• MBT philospohy
• MBT treatment mechanics
• Conclusions
• References

3. MBT was developed by
• Richard P Mclaughlin
• John C Bennet
• Hugo J Trevisi

4. INTRODUCTION
• Straight wire appliance(SWA) developed by ANDREWS
changed the concept of standard edgewise system.
• ROTH’S most important contribution to orthodontics was
introduction of FUNCTIONAL OCCLUSION and
spreading SWA as ROTH SETUP

5. FIRST GENERATION PEA
• Available from 1972
• It had Siamese edgewise
brackets
Drawbacks:
• Traditional heavy
edgewise forces continued
to be used
• No specific measures
were employed to control
anchorage.

6. • In the early years of PEA, heavy forces were used and these
were associated with deepening of the anterior bite and
creation of lateral open bite –”ROLLER COASTER EFFECT”

7. SECOND GENERATION PEA
• After few years of clinical experience
with SWA, Roth identified the short
comings of SWA like multiple
bracket system.
• Used a wider arch form than
Andrews to avoid damage to canine
tips during treatment
• He emphasized the use of
articulators for
• Diagnostic setup
• Early splint construction
• Construction of gnathologic
positioners at the end of the
treatment.

8. THIRD GENERATION PEA
• Work of Mc Laughlin and Bennett between 1975-1993
• The science and tradition which went to the original
design are now balanced by wealth of clinical
experience.

9. • Work of Mc Laughlin and Bennett and Trevisi between
1993-1997

10. • Work of Mc Laughlin and Bennett and Trevisi
between 1997-2001

11. • MBT developed the treatment mechanics based on
• Sliding mechanics
• Light continuous forces
• Lace back and bend back
• Designed to work ideally with sliding mechanics

12. McLaughlin, R.P., Bennett, J.C. The transition from standard edgewise to preadjusted appliance
system. J Clin Orthod. 1989;23:142–153.
McLaughlin, R.P., Bennett, J.C.(1989).
The most significant changes in mechanics that occurred during the transition
period from standard edgewise to preadjusted appliance systems.The changes
are grouped under the six sequential but overlapping phases:
Anchorage : Need for early anchorage control was identified for which omega
loops and molar tiebacks were used to control incisor and canine positions.
Leveling & aligning : 6-7mm of space opening in the anterior segments over
six months, while leveling proceeds from light, multistranded wires into .020"
round wires. If this space is more than desired the lacebacks are discontinued
before leveling is completed.

13. Overjet & overbite : When the cuspids are upright or even more distally
inclined, the effective way to manage this situation is to leave the incisors
unbracketed, and place lacebacks to the cuspids, and wait for the cuspid roots
to distalize and the cuspid slots to become more parallel to the occlusal plane.
Space closure : Single elastic modules to anterior archwire hooks with ligature
wires extended forward from the molars and when activated 2-3mm, generate
about 100-150g of force and delivers .5-1.5mm of space closure per month
Finishing : Source: The appliance prescriptions are based on averages, they
cannot possibly account for all the variations of tooth size and shape. This
means that detailing bends will be needed in the finishing wires of some
patients.

14. Bennett, J.C., McLaughlin, R.P. (1990).
They have given the basic principles of space closure :
Mechanics of Space Closure : The force required for space closure is delivered
by elastic "tiebacks" which is stretched by 2-3mm twice its normal length.
Inhibitors to Sliding Mechanics : Three primary sources of friction during
space closure .
First-order or rotational resistance at the mesiobuccal and distolingual aspects
of the posterior bracket slots is produced by rotational forces on the buccal
aspects of the posterior teeth.
Second-order or tipping resistance at the mesio-occlusal and distogingival aspects
of the posterior bracket slots is caused by excessive and overactivated tieback
forces, which lead to tipping of the posterior teeth.
Bennett, J.C., McLaughlin, R.P. Controlled space closure with a preadjusted appliance system. J Clin
Orthod. 1990;24:251–260.

15. Third-order or torsional resistance occurs at any of the four areas of the bracket
slot where the edges of the archwire make contact. Like tipping resistance, this
is produced mainly by excessive and overactivated tieback forces,

16. Stephen Burke et al.(1998) applied 26 previous studies to assess the
longitudinal stability of postretention mandibular intercanine width.
They found that mandibular intercanine width tends to expand during
treatment 0.8 to 2mm.
Mandibular intercanine width tends to constrict postretention by 1.2 to 1.9
mm.
Burke S P., SilveiraA M., Goldsmith, Yancey, Stewart,Scarfe. A meta-analysis of mandibular
intercanine width in treatment and postretention.Angle orthod 68(1):53-60

17. Thomas ,Steve ,Nicole (2007) : They found that added force to overcome
friction during canine retraction in sliding mechanics, the result of which can
be increased anchorage loading and anchorage loss.
The frictional force that reduces the force of retraction on the canine must also
reduce the protraction force on the molar.
Emphasis on using reduced-friction( selfligating) brackets during sliding
mechanics to help preserve posterior anchorage.
Southard, T.E., Marshall, S.D., Grosland, N.M. Friction does not increase anchorage loading. Am J
Orthod Dentofacial Orthop. 2007;131:412–414.

18. Xiaomo Liu;Peng Ding;Jiuxiang Lin.(2013): Explore how the position of the
bracket slots relative to the archwire influences the friction between them, and
how bracket design affects the critical contact angle (Ѳc).
In their study they used two kinds of stainless steel archwires (0.016 and 0.019 x
0.025-inch)were tested against four kinds of brackets (Transmission Straight
Archwire bracket, Domestic MBT bracket, Tip-Edge Plus bracket, and BioQuick
self-ligation bracket) in the dry state.
They found that the relationship between the archwire and bracket slot
significantly affects the resistance to sliding.
Liu,ding,lin. Effects of bracket design on critical contact angle. Angle Orthod. 2013;83:877–884.

19. Mohit Mittal; Badri Thiruvenkatachari; Paul Jonathan Sandler; Philip E.
Benson(2015): Investigate if there are any significant differences in the final
inclination of the upper and lower anterior teeth of patients treated with a
Roth or an MBT bracket prescription.
Forty sets of posttreatment study models from patients treated using a
preadjusted edgewise appliance (20 Roth and 20 MBT) were selected using
predetermined inclusion and exclusion criteria.
They found thatthere were no statistically significant differences in terms of
the final inclination of the anterior teeth between the two bracket
prescriptions.
Mittal,Thiruvenkatachari,Jonathan,Benson. A three-dimensional comparison of torque achieved with
a preadjusted edgewise appliance using a Roth or MBT prescription. Angle Orthod. 2015;85:292–297

20. MBT TREATMENT PHILOSOPHY
1. Bracket selection
2. Versatility of bracket system
3. Accuracy of bracket position
4. Light continuous force
5. 0.022 versus 0.018 slot
6. Anchorage control early in treatment
7. Group movement
8. Use of 3 arch forms
9. One size of rectangular steel wire
10. Arch wire hooks
11. Methods of arch wire ligation
12. Awareness of tooth size discrepancies
13. Persistence in finishing

21. BRACKET SELECTION
• AVAILABLE IN 3
• STANDARD SIZE METAL BRACKETS
• MID SIZE METAL BRACKETS
• ESTHETIC BRACKETS

22. • Brackets are rhomboidal in shape and have reduced bulk so
coordination is only in 2 planes which assists in accuracy of
bracket placement.

23. TIP SPECIFICATION
MBT TIP

24. • The tip of pre adjusted
brackets is fully expressed
and there is 1 degree of slop
when a .019/.025 rectangular
wire is placed
• Upper and lower molar
attachment have 0 degree tip
when placed parallel to the
buccal cusps of molars this
delivers 5 degree tip in upper
and 2 degree tip in lower.

25. TORQUE SPECIFICATION

27. Torque in the base
• Important issues in 1st and 2nd generation PEA was level slot
line up was not possible with brackets with torque in the face
• In MBT versatile brackets are finished with all the torque in
the base in
• Full size metal brackets and esthetic brackets
• Combination of torque in the base and face with absolutely no difference
in slot position in mid size brackets

28. There is 10 degree of slop when a 0.019/0.025 wire
is placed in a 0.22 slot

29. • TORQUE is not efficiently expressed in PEA due to 2
mechanical reasons
1. Area of torque application is small
2. In order to slide the teeth it uses under sized arch wire so torque would not
be fully expressed.

30. Need of extra torque in incisors
• When class II elastics are used ( in class II cases) there is a
tendency for the torque to be lost on the upper incisors and
lower incisors tend to procline during leveling in response to
class II cases.
• In class I cases, where correct incisor torque helps for better
anterior tooth fit.
• Class III cases where correct torque can compensate for mild
class III dental bases.
• Due to this frequent clinical requirements there is a need for greater
palatal root torque in upper incisors and labial root torque in lower
incisors
• +17 and +10 for upper central and lateral and -6 for lower incisors are
recommended by MBT

32. Canine torque
• Original SWA -11 torque for
lower canine was not
satisfactory because it tends to
leave canine in a prominent
position
• +7,0,-7 - upper canines
• +6,0,-6 - lower canines
• -7/-6 -square or ovoid arch form
• 0/0 -ovoid or tapered arch form
• +7/+6- tapered arch form

33. 6 factors which determine selection of canine
brackets
• Arch form
• Canine prominence
• Extraction decision
• Over bite
• Rapid palatal expansion
• Agenesis of upper lateral incisor

34. Upper premolar and molar torque
• Upper premolar torque of -7
is considered adequate.
• In molars MBT has found -9
torque in SWA is
inadequate so they prefer -
14 so as it gives better
control over the palatal
cusps from hanging down.

35. Lower premolar and molar torque
• Original SWA molar torque(-30)
• 2nd molar torque(-35) causes “rolling in” of lower
molars.
• So MBT brackets they changed lower premolar
brackets by 5 ,1st molar by 10, and 2nd molar by 25
degrees.
• -17 2nd premolar
• -20 1st molar
• -10 2nd molar

36. VERSATILITY OF BRACKET SYSTEM
Seven main versatility features :
•Options for Palatally displaced lateral incisor
• Three torque options for upper canine
• Three torque options for lower canine
• Interchangeable lower incisor brackets
• Interchangeable upper premolar bracket
• Use of upper second molar tubes on first molar in non HG cases
• Use of lower second molar tubes for upper first and second
molars of opposite side
36

37. PALATALLY DISPLACED LATERAL INCISOR:
37

38. TORQUE OPTIONS FOR UPPER CANINE
LOWER CANINE
38

39. Interchangeable lower incisor
brackets
39
Interchangeable

40. Interchangeable upper premolar brackets
40

41. In non-HG cases  Use of upper
second molar tubes on first molars
41

42. second molar tubes for the upper first and second molars of the opposite side.
42

43. 0.022 v/s 0.018 inch slot
• PEA system works well in 0.022 slot
 More freedom of wire in a larger slot in initial phase of
treatment – lighter force
 Later in the treatment full slot engagement gives control
for retraction
 Rigidity for surgical / fixed functional treatment
43

44. BRACKET POSITIONING
• “In the past best results were achieved by orthodontist who
were the best wire benders ,in the future best results come
from those orthodontist who are best bracket positioners”-
MBT”

45. Accuracy of bracket positioning is essential, so that the
built-in features of the bracket system can be fully and
efficiently expressed. This helps treatment mechanics and
improves the consistency of the results.

46. • In 1990 because of continuing difficulty with vertical bracket
positioning, McLaughlin and Bennett investigated the location of
the centre of clinical crowns.
• MBT recommends vertical positioning of brackets with gauges
and charts.

47. In the incisor region, the gauge is placed at 90° to the labial surface
In the canine and premolar regions the gauge is placed parallel
with the occlusal plane.

48. In the molar region the gauge is placed parallel with the occlusal
surface of each individual molar.

50. Technique for choosing rows
• Step 1-dividers and millimeter rulers are used to measure the
clinical crown height on as many fully erupted teeth as possible
on patients study model.
• Step 2-these figures are recorded and is divided into half
rounded to nearest 0.5mm to obtain distance from occlusal
surface to the centre of clinical crown.
• Step 3-the row on the bracket placement chart that contains the
greatest number of recorded figure is selected for bracket
placement.

51. Chart individualized in deep bite
and open bite cases.
• It is helpful to place the incisor and canine bracket 0.5
mm more
• Incisally in deep bite cases.
• Gingival in open bite cases.

52. premolar
extraction cases

53. ARCH FORM SELECTION
• Recent classification according to MBT system is
• Tapered arch form
• Square arch form
• Ovoid arch from

54. • Tapered arch form
o Has the narrowest inter canine width useful in
patients with narrow tapered arch forms
o Arch is useful in patients with gingival recession
in canine and premolar
o This arch form is used in combination with
inverted canine bracket.

55. • Square arch form.
o Used with broad arch from
o Example class II div-2
o Maintain the expansion of upper arch after
RME.

56. • Ovoid arch form
• This arch form has been used as
the standard arch form
• This arch form has shown good
stability
• Minimal amount of relapse

57. Customization of arch form
MBT RECOMMENDS USE OF CLEAR TEMPLATES AT THE
START OF THE TREATMENT.
LOWER MODELS.

58. Arch form control in early stages of
treatment.
• Multi strand 0.0175” or 0.016” round HANT are used in
treatment.
• MBT recommends to use ovoid arch form during initial stage
without any customization due to 2 reasons :
• Low dimension wires do not exert heavy force on teeth so as to change the arch
form drastically.
• Have little effect on the arch form for the short period of time it is used.

59. Arch form control during
treatment
• Rectangular HANT cannot be customized
• So stocked in tapered, ovoid and square.
• 0.019/0.025 S.S when placed should be customized for
individual arch form.

60. A wax template is mounted over the lower arch to record the
indentation of the bracket.

61. 0.019/0.025 S.S is bent to the indentation of the wax bite
It is called as IAF-INDIVIDUALIZED ARCH FORM.

62. COORDINATION:-Upper arch form should be approximately 3 mm
wider than the lower arch form in all areas.

63. 63
• Modification after maxillary expansion
Modifications to Arch Form

64. 64
• Upper arch expansions with archwires

65. Anchorage control in MBT
• Tooth leveling and aligning is first orthodontic objective
during initial stage of treatment.
• Maximum anchorage is needed during leveling and aligning
procedures.

66. Reducing anchorage needs during leveling and
aligning.
• Bracket design in MBT:-
o Bracket tip is major factor in
anchorage demands early in
treatment
o Reduction in tip reduces the
anchorage potential in the
case
o MBT bracket system has
• 10 degree less distal tip in
upper anterior segment.
• 12 degree less distal tip in
lower anterior segment when
compared with SWA.

67. • Arch wire forces:-
• Use of very light arch wire forces early in treatment will put less
demand on anchorage.
Avoidance of elastic chain

68. Anchorage control in MBT.
• Horizontal plane.
o Control of anterior segments
• Lace backs :-lace backs are 0.010’’ or 0.009’’ ligature wire which extends
from the most distally banded molar to canine bracket.

69. •Lace back are used to prevent the canine crowns from moving forward
during leveling and aligning.
•Mainly used in premolar extraction cases and also in non extraction cases
where the canine root is mesially tipped
•Lace backs are passive devices and should not be over tightened
•It is shown that lace back can be a effective method of distalizing canine
without unwanted tipping.

70. • Bend backs for anterior-posterior incisor control.
• The arch wire is bent back immediately behind the tube on most distally banded molar
• This serves to minimize the forward tipping on incisors

71. •Control of posterior segments.
• Upper arch
o Head gears
o TPA
o Nance holding arch
• Lower arch
•Lingual arch
•Lip bumper
•Class III elastic and head gear

72. Lateral or transverse plane
• Maintenance of upper and lower inter canine width
• Correction of molar cross bite if present
• RME
• QUAD HELIX
• TPA.

73. 73
Vertical Anchorage Control During
Leveling & Aligning
• Vertical control of incisors

74. 74
• Vertical control of canines

75. 75
• Vertical control of molars in high angle cases
o Palatal bar
o Upp 2nd molars not initially banded
o Headgear – high pull

76. 76
Overbite Control
• Development of Deep Overbite
• Anterior teeth continue to erupt until contact is made with
opposing ant teeth

77. 77
• Development of Deep Overbite
• Unrestricted eruption of low 2nd molars in cl II

78. 78
• The tooth movements of bite opening -
o Eruption/extrusion of post teeth
o Distal tipping of post teeth
o Proclination of incisors
o Intrusion of incisors
o A combination of two or more of the above

79. 79
• Eruption/extrusion of post teeth
o Growing pts
 Adults – low angle
 Adults – high angle

80. 80
• Distal tipping of post teeth

81. 81
• Proclination of incisors
o Deep bite with retroclined incisors

82. 82
• Intrusion of anterior teeth
o Growing pts – preventing normal eruption
o Adults – intrusion arches

83. 83
• Non-Extraction treatment
o Generally favors bite opening
• Mechanical factors contributing to bite opening
o Initial archwire placement
o The bite-plate effect

84. 84
• The bite-plate effect
o Allows for early placement of low incisor
brackets
o Intrusive force on low incisors
o Allow for extrusion/uprighting of post teeth

85. 85
• Creating the bite-plate effect
o Acrylic ant bite plates
• Low angle deep bite cases

86. 86
• Creating the bite-plate effect
o Direct bonding material on palatal surface of upp incisors
o High angle – occlusal surfaces of molars

87. 87
• The importance of second molars
o Low-angle deep bite cases – earliest banding of 2nd molars

88. Importance of friction in orthodontics
• Applying the proper magnitude of force during
orthodontic treatment will result in optimal tissue
response and rapid tooth movement.
• With orthodontic mechanotherapy, a biologic tissue
response with resultant tooth movement will occur
only when the applied forces adequately overcome
the friction at the bracket wire interface

89. Initial leveling in MBT.
• Initial arch wire for alignment should provide light
continuous force to provide most efficient tipping
movement.
• Arch wire should move freely inside the slot with
minimal binding

90. MBT advocates
• Use the lightest possible force to produce tooth movement
• Do allow sufficient time for up righting of teeth especially
canines
• Do not move up to next arch wire unless full bracket
engagement has been achieved with present arch wire
• Do not leave initial arch wire unless rotational control has
achieved.
• Do not attempt to align a tooth unless there is adequate space
available.

91. Space closure and sliding mechanics.
• 2 schools of thought for retraction
o First is canines and incisors are retracted separately to conserve anchorage
o Second is enmasse retraction where all 6 anterior teeth are retracted at the
same time.
o MBT advocates enmasse retraction in their cases

92. WIRE SELECTION IN SLIDING
MECHANICS.
• Space closure in sliding mechanics require a wire which
produces less friction between brackets.
• Rectangular wire produce more friction the round wires and
larger wires produce more than smaller wires
• Cobalt chromium, beta titanium and Ni Ti produce more
friction than stainless steel due to the surface topography of
the wire.

93. • 0.016 stain less steel round wire has lowest friction but it is not
good for sliding because wire does not offer control in all 3
planes of space and gets distorted easily and causes excessive
tipping and more friction.
• So 0.016x 0.022 S.S in 0.018 slot and 0.019 x 0.025 S.S in
0.22 slot for ideal sliding mechanics.
• Composition of brackets will also affects sliding mechanics.
Ceramic brackets create more friction than stainless steel.

94. Methods of space closures
• Closing loop arch wires
• Sliding mechanics with
heavy forces (edge wise
mechanics)
• Elastic chain
• Sliding mechanics with
light continuous forces.
(MBT)

95. Space closure in MBT.
• ARCH WIRES.
o Rectangular 0.019 x 0.025
stainless steel wires in
0.022 slot.
o This is working wire in
MBT.
o This wire gives good over
bite control while allowing
free sliding through the
buccal segments.

96. • Soldered hooks
o 0.7 mm soldered brass hooks are
preferred.
o Most common hook position are 36
mm or 38 mm in upper and 26 mm
(lower).

97. • Passive tie backs
o Before starting space closure it is recommended that rectangular 0.019 x 0.025
wire left in place for at least 1 month with passive tie back
o It allows time for torque changes to occur individual tooth for final leveling of
arches so sliding mechanics can proceed smoothly

98. • Active tie back using electrometric modules.
o Active tie back using electrometric modules are preferred for space closure in
most case.
o There are 2 types of active tie back
o Type one active tie back ( distal module)
o Type two active tie back (mesial module)

99. Type one active tie backs (distal module)
One arm of ligature wire is carried under the arch wire. The
electrometric module is stretched twice to unstretched size.

100. Type two active tie backs (mesial module)
• Here the electrometric module is placed on
the soldered hook of the arch wire.

101. Force levels
• It was found when modules were stretched twice it was found to
give 50 -100 gms after pre stretching
• Without pre stretching it is 200-300 gm .
• Natrass et al has confirmed that force decay of elastomeric
chains is rapid in the first 24 hrs and is affected by oral
environment and temperature.
Nattrass C, Ireland A J, Sheriff M: An investigation into the placement of force
delivery systems and the initial forces applied by clinicians during space
closure. BJO 1997:24:127-131

102. Other methods
• Using nickel titanium
springs.
o It can be used when
large spaces has to be
closed
o If there is infrequent
adjustment opportunities

103. • Samuels et al have found that optimal force while using Ni-Ti
coil spring is 150 gms.
• Springs should not be expanded beyond 22 mm for 9 mm
springs and 36 mm for 12 mm springs.
Samuels R H, Rudge S J, Mair L H: A comparison of the rate of space closure using a nickel-titanium
spring and an elastic module: a clinical study, Am J Orthod 1993:103:464-467
Samuels R H, Rudge S J, Mair L H: A clinical study of space closure with nickel-titanium closed coil
springs and an elastic module: Am J Orthod 1998:114:73-79

104. TRAMPOLINE EEFECT.
• Clinical experience have showed space closure can continue
for several months who have failed to present for normal
adjustments and elastomeric module is poor condition with
little force.
• This is explained by “trampoline effect” which occurs during
the mastication which result in pumping activation.

105. Check list after space closure
• Anchorage maintenance should be evaluated.
• Occlusal plane of anterior and posterior teeth must be
evaluated.
• Axial inclination of the teeth (ex-root parallelism)
• Rotation of teeth

106. THE FINISHING TOUCH.
• “Finishing greatly affects stability" Hickman 1992
• Accurate arch form and accurate coordination, less work is
required for finishing

107. Finishing the case:-
• Condyles seated in centric relation position.
• Relaxed healthy musculature
• A six keys Class I occlusion
• Ideal functional movements- a mutually protected occlusion
• Periodontal health
• Best possible esthetics.

108. Final stage of finishing
• Lighter wires are used for settling because heavy
wire inhibit the settling of the teeth.
• 0.014/0.016 braided s.s or HANT wire are used.
• It is accompanied by vertical triangular elastics

109. 110
• Lower - .014” or .016” NiTi or .014” steel
• Upper - .014” SS sectional
• 4-6 weeks

110. 111
Settling The Case
• Variations
o Cuspids
o Diastema
o Extraction – fig 8 ligatures
o Palatal expansion
o Mod to severe Class II/1

111. Management of tooth size
discrepancy.
• Tooth size is considered the 7th key of normal occlusion.
• Tooth size discrepancy may be corrected by reducing
tooth mass in one arch with inter proximal enamel
reduction.
• By adding restorative materials in the opposing arch.

112. Wire Selection in the MBT Versatile+
Appliance System
• It is the wire that drives or guides the teeth, no matter
how advanced the brackets may be, or whether they are
self-ligating or not.

113. Archwire role
• It has 2 modes of action
1. In this, the wire is in its active state. Activation of the
wire is carried out by ligating the archwire to the
irregularly positioned teeth. Energy is stored by
pushing the elastic wires into the bracket slots. After
this activation, the archwire uses this energy to move
the teeth. Such an operating mode is typical for the
aligning and leveling stages.

115. 2. In this, the archwire is used as a guiding track for the mesial or
distal movement of teeth along the arch. Here the archwire is
initially passive and its stiffness and elasticity only comes into play
when the teeth start to show side effects such as tipping or
rotations.
Then the wire creates corrective forces and moments and assures
that the teeth do not deviate from the intended track and
angulations.

116. CONCLUSIONS
There is no such thing as an isolated orthodontic
act. More effort and knowledge is required to
prevent or control unwanted tooth movements than
to apply the primary forces

117. References
• Mclaughlin RP, Bennett JC, Trevisi HJ: Systemized orthodontic
treatment mechanics: published by Mosby
• Samuels R H, Rudge S J, Mair L H: A comparison of the rate of
space closure using a nickel-titanium spring and an elastic module:
a clinical study, Am J Orthod 1993:103:464-467
• Nattrass C, Ireland A J, Sheriff M: An investigation into the
placement of force delivery systems and the initial forces applied by
clinicians during space closure. BJO 1997:24:127-131
• Samuels R H, Rudge S J, Mair L H: A clinical study of space closure
with nickel-titanium closed coil springs and an elastic module: Am J
Orthod 1998:114:73-79
• McLaughlin, R.P., Bennett, J.C. The transition from standard
edgewise to preadjusted appliance system. J Clin Orthod.
1989;23:142–153.
• Bennett J C, McLaughlin R P 1990 Controlled space closure with a
preadjusted appliance system. Journal of Clinical Orthodontics
24:251-260

118. THANK YOU