FUNCTIONAL APPLIANCE

1. TWIN BLOCK

2. CONTENTS
• INTRODUCTION
• HISTORY
• DESIGN OF TWIN BLOCK
• RESPONSE TO TWIN BLOCK TREATMENT
• SKELETAL CHANGES
• DENTAL CHANGES

3. • STANDARD TWIN BLOCK
• STAGES OF TREATMENT
• INDICATIONS
• CONTRAINDICATIONS
• MODIFICATIONS
• ADVANTAGES

4. Twin blocks are simple bite
blocks with occlusal inclined
planes.

5. INTRODUCTION
comprises of separate upper and lower units
which are not joined together.
simple bite blocks designed to be worn 24 hours
a day
achieve rapid functional correction of
malocclusions by transmitting favourable
occlusal forces to occlusal inclined planes that
cover all posterior teeth.

6. HISTORY
• The first Twin Block appliance
was fitted on 7th September
1977 by William Clark.
• Evolved in response to a clinical
problem.
• Young patient who was son of a
dental colleague fell and
luxated theupper incisor
The twin block technique A functional orthopedic appliance system
WJ Clark - American Journal of Orthodontics and Dentofacial …, 1988

7. THE PATIENT WAS 8YRS AND 4 MONTHS

8. ENDODONTIC PINS WERE PLACED TO STABILIZE THE INCISOR, 4
MONTHS AFTER TREATMENT

9. DESIGN OF TWIN BLOCK
Occlusal inclined plane
• The occlusal inclined plane is the fundamental functional
mechanism of dentition.
• Cuspal inclined planes play an important part in determining the
relationship of the teeth
• If the mandible occludes in a distal relationship to the maxilla
(in class II) the occlusal forces acting on the mandible in normal
function have a distal component of force that is unfavorable to
normal forward mandibular development.

10. Twin-blocks constructed in a protrusive bite ,effectively
modifies the occlusal inclined planes by means of bite-
blocks

11. The bite blocks acts as a guiding mechanism causing the mandible to
be displaced downward and forward.
The unfavorable cuspal contacts of a distal occlusion are replaced by
favorable proprioceptive contacts on the inclined planes of twin-
blocks to correct the malocclusion & to free the mandible from its
locked distal functional position.

12. MANDIBLE UNLOCKED

13. RESPONSE TO TWIN BLOCK
TREATMENT
When the mandible postures
downward and forwards,there is
an area of immense cellular
activity above and behind the
condyle referred as Tension
Zone. This area is quickly
invaded by proliferating blood
vessels and connective tissue.
The twin block technique A functional orthopedic appliance system
WJ Clark - American Journal of Orthodontics and Dentofacial …, 1988

14. A new pattern of muscle behaviour is quickly established
whereby the patient finds it difficult and impossible to retract
the mandible to its former retruded position.
PTERYGOID RESPONSE
The muscles are the prime movers in growth, followed by bone remodelling
as a secondary response. Hence muscle function must be altered over a
sufficient period of time to allow adaptive bone remodelling changes to
occur, in order to reposition the condyle in the glenoid fossa.
McNamara JA. Neuromuscular and skeletal adaptations to altered function in orofacial region. AJO

15. SKELETAL CHANGES IN TWIN BLOCK
THERAPY
Forward
growth/repositioni
ng of the mandible
is seen after twin
block therapy.
Increase in SNB
angle.

16. Little change in SNA angle indicating maxillary
restraint, but was not detected because of
dentoalveolar remodeling disguising the skeletal
effect.
Forward growth/repositioning of the mandible does
result in a significant change in ANB, thus severity of
the class II skeletal pattern is reduced.
Increase in lower anterior facial height.

17. overjet reduction
retroclination of the upper incisors
proclination of the lower incisors.
Buccal segment correction occurred by distal movement of the upper
molars
lower molar eruption in an anterior and superior direction.
Dental changes as a result of Twin Block therapy

18. STANDARD TWIN BLOCK
• treatment of an uncrowded class II div 1 malocclusion with a
good arch form.
Clark’s Twin Block appliance consists of:
• Base Plates
• Bite block
• Wire components: The Delta Clasp and Ball End Clasp
• Other related components

20. • BASE PLATE
HEAT CURE
COLD CURE
additional strength and good accuracy
speed and easier manipulation.

21. BITE BLOCK
The inclined plane on lower bite block
is angled from the mesial surface of
the second premolar or deciduous
molar whichever present.
the lower bite block does not extend
distally to the marginal ridge on the
lower second premolar.
This allows the leading edge of the
inclined plane on the upper appliance
to be positioned mesial to the lower
first molar so as not to obstruct
eruption

22. The inclined planes are mostly angled at 70 degrees to the occlusal plane,although
the angulation may be reduced to 45 degrees if the patient fails to posture
forwards consistantly

23. WIRE COMPONENTS
DELTA CLASP
designed by
Clarke
retentive loops are
shaped as a closed
triangle or a circle
gives excellent retention
on lower premolars

24. BALL END CLASP
are routinely placed
mesial to lower canines
and in the upper
premolar or deciduous
molar regions for
interdental retention
from adjacent teeth

25. BITE REGISTRATION
-mandible should be positioned protruded approximately 3mm distal
to the most protrusive position that the patient can achieve ,while
vertically the bite is registered within the limit of the freeway space.
Woodside-
1977
Woodside DG (1977) The activator. In: Graber TM, Neumann B, editors. Removable
Orthodontic Appliances. Philadelphia: Saunders; pp. 269-336.

26. normal physiologic TMJ movement as 70% of the total joint
displacement.
Roccabado
edge to edge incisor relation with 2mm interincisal
clearance.
Overjet
upto 10mm

27. The Exactobite or the project bite
gauge is used to record a protrusive
interocclusal record for the
construction of the Twin Block.
The George bite gauge has a millimetre
gauge to measure the protrusive path
of the mandible and determine
accurately the amount of activation
registered in the construction bite.

28. • Activation should be within the masticatory muscle
physiologic limit and ligament attachment limit.
• Total protrusive movement =
overjet in centric occlusion – max protrusion possible
• Functional activation should not be more than 70% of
above value

29. • Overjet greater than 10mm-
initial activation of 7-8mm
followed by further activation.
• Vertical dimension-
should be 4 – 5mm(in the first premolar region).

30. SUMMARY OF BITE REGISTRATION
• Inter incisal clearance 2mm
• In first premolar region 5-6mm
• Molar region 1- 2mm
Design and management of Twin Blocks:reflections after30 years of clinical use
William Clark

31. STAGES OF TWIN BLOCK TREATMENT
Active
phase
Support
phase
Retention

32. ACTIVE PHASE
6-9
MONTHS

33. • the appliance is used to achieve correction of sagittal jaw
position.
• After correction vertical discrepancy is corrected by
selectively trimming the posterior bite blocks.
• achieve correction to class I occlusion and control of
the vertical dimension by a three-point contact with
the incisors and the molars.
• At this stage the overjet ,overbite and sagittal
relationship is full corrected.
AIM

34. SUPPORT PHASE
4-6
MONTHS

35. AIM
• to maintain the corrected incisor relationship until the buccal
relationship is fully interdigitated.
• To achieve this objective an upper removable appliance is fitted
with an anterior inclined plane with a labial bow to engage the
lower incisors and canines.

36. ANTERIOR INCLINED PLANE

37. RETENTIVE PHASE
9
MONTHS

38. • Treatment is followed by retention with upper anterior
inclined plane appliance.
• Appliance wear is reduced to nighttime wear only when
the occlusion is fully established.

39. FIXED APPLIANCE PHASE
Final detailing of the occlusion is completed using
fixed appliance therapy

40. INDICATIONS

41. Class II div I
malocclusion.
The following is a good general selection criterion:
• Permanent dentition and active grower
• Uncrowded dentition with well developed arches
• 10mm or less overjet with normal to deep overbite
• Improved facial esthetics once the mandible is brought forward to
class I
• Normal growth direction
• if patient is Class II div 2 with limited overjet or Class II div 1 with
crowded and irregular incisors, align the upper incisors with a
fixed or removable appliance before starting a twin bloc.

42. CONTRAINDICATIONS

43. Class II skeletal by maxillary
prognathism
2. Vertically directed grower
3. Labial tipping of lower incisors
4. Crowding

44. MODIFICATIONS OF TWIN BLOCK

45. TRANSVERSE
DEVELOPMENT
SAGGITAL
DEVELOPMENT
SAGGITAL AND
TRANSVERSE
DEVELOPMENT
TO CLOSE
ANTERIOR OPEN
BITE
Twin block for
arch
development

46. TWIN BLOCK FOR TRANSVERSE DEVELOPMENT

47. TWIN BLOCK FOR SAGITTAL DEVELOPMENT

48. FOR BOTH TRANSVERSE AND SAGITTAL
In cases of laterally contracted maxillary arch;
combined sagittal and tranverse expansion is
required.This is brought about by
• Three way sagittal appliance.
• Triple screw sagittal appliance.

49. • This is mainly due to a combination of skeletal and soft tissue
factors.
• Bite registration
A 4mm interincisal clearance is achieved, resulting in approximately
5mm clearance between the premolars or the deciduous molars.
Sufficient block thickness is needed so as to open the bite beyond the
freeway space – for intrusion of the teeth and at the same time makes
it difficult for the patient to disengage the blocks.

50. TWIN BLOCK TO TREAT ANTERIOR OPEN BITE

51. • APPLIANCE DESIGN
The lower appliance extends distally to the molar region with clasps
on the lower first molars and occlusal rests on the second molars to
prevent their eruption.
For the upper appliance
Expansion screws for arch expansion
A palatal spinner to control the tongue thrust
A tongue guard
A labial bow may be added to retract the upper incisors.

52. Pitfalls in the treatment of anterior open bite arise from
careless management of the occlusal bite blocks.
Two common mistakes are to be avoided:
1. The over eruption of the second molars behind the
appliance
2. Trimming of the upper bite block occlusally which allows
the lower molars to erupt thereby propping the bite open
and increasing the open bite

53. TREATMENT OF CLASS II, DIV I MALOCCLUSION
• Edge to edge bite with 2mm
interincisal clearance.
• Center lines should coincide.
• In vertical dimension 2mm interincisal
clearance is equivalent to clearance in
first premolar region by 5-6mm and
3mm in the molar region

54. APPLIANCE DESIGN

55. Trimming -1-2 mm /visit
Molars erupt 6-9 months
Triangular wedge shaped area
Eruption of the pre molar

56. • Reduce the overjet and correct
distal occlusion.
• Control overbite if the
overbite is deep or an anterior
open bite is present .
• Improve arch form by sagittal
or transverse development.
• C- shaped clasps can be
bonded to deciduous teeth for
improved retention.
TREATMENT OF MIXED DENTITION

57. TREATMENT OF CLASS II DIV 2 MALOCCLUSION
• An edge to edge construction
bite is registered to correct the
distal occlusion in class Il
division, 2 malocclusion.
• Management of Class Il div 2
malocclusion by advancing the
mandible and proclining the
upper incisors with sagittal
screws.
• Eruption of lower molars
corrects vertical dimensions

58. APPLIANCE DESIGN
For the treatment of Class II Div 2 malocclusions , sagittal arch
development is necessary.
• Sagittal Twin Blocks are used
Upper block is modified by addition of two sagittal screws set
in the palate for anteroposterior arch development.
• The sagittal design is suitable for both upper and lower arches to
increase the arch length.

59. TREATMENT OF CLASS III MALOCCLUSION
• Reverse twin blocks are designed
to encourage maxillary
development.
• reverse occlusal inclined plane
cut at a 70 degree angle drive
the teeth forwards by the forces
of occlusion
• restrict forward mandibular
development.

60. • POSITION OF THE CONDYLES

61. • Modification-
lip pads may be used to
support the upper lip
clear of the incisors.

62. • Teeth closed to the maximum retrusion, leaving sufficient clearance
between posterior teeth for occlusal bite blocks .
• Achieved by recording bite with 2 mm interincisal clearance in fully
retruded position.
Appliance design:-
 In many cases, the maxilla is contracted in relation to occluding in distal
relation to the mandible.
 The three —way expansion screw to combine transverse and sagittal
expansion.
 Opening the screw has reciprocal effect of driving upper molars distally
and advancing the incisors.

63. MAGNETIC TWIN BLOCK
Two rare earth magnets used
Samarium Cobalt
Neodynium Boron
ATTRACTING
MAGNETS
REPELLING
MAGNETS

65. ATTRACTING MAGNETS
Increased activation can be built
into the initial construction bite for
the appliance.
Attracting magnets pull the
appliances together and
encourages the patient to
occlude actively and consistently
in a forward position.
Attracting magnets may
accelerate progress by increasing
the frequency and force of
contact on the inclined planes.

66. REPELLING MAGNETS
• apply additional stimulus to forward posture the jaw as the
patient closes into occlusion.
• amount of activation
is not clear
• reactivation of the
inclined plane would
deactivate the
magnets.
DISADVANTAGE

67. TWIN BLOCK IN TMJ THERAPY

68. GOALS -relieve pain by distal displacement.
-restrain muscles to healthy pattern.
-recapture disc by advancing mandible.
-move teeth causing occlusal balance.
-increase the vertical dimension.

69. STAGES OF TREATMENT
SAGGITAL
DEVELOPMENT

70. Functional repositioning
Pain relieved immediately
Muscles are restrained
Disc is recaptured

71. Vertical development
Trimming the upper blocks
Vertical traction
Twin block biofinisher

72. • TWIN BLOCK BIOFINISHER
Extruding lower molars by vertical traction to stabilize the TMJ

74. It is important to recognize that if pain is not relieved by
forward posture, and the disc does not appear to be
recaptured, there may be internal derangement, or folding
of the disc. which will not respond to Twin Block therapy.

75. • Myofunctional therapy after maximum and stepwise
advancement with the Twin Block appliance showed a
favourable effect in the temporomandibular joint region.
Stepwise advancement showed greater vertical growth and
more favourable anteriorly directed horizontal growth in the
temporomandibular joint region on a short-term basis
Doshi et al, Effective temporomandibular joint growth changes after stepwise and
maximum advancement with Twin Block appliance, Journal of the World Federation of
Orthodontists 3 (2014) e9-e14

76. TREATMENT OF FACIAL ASYMMETRY
• Occlusal inclined planes-
capable of unilateral activation.
• Use of magnets.

78. FIXED TWIN BLOCK
Increase control by the operator
Limited indications-
• Growth status of the patient
• Patient cooperation.
• One phase treatment is planned.

79. 1st
• ARCH DEVELOPMENT
2nd
• ORTHOPAEDIC TREATMENT BY
FIXED/FUNCTIONAL TWIN BLOCK
3RD
• ORTHODONTIC CORRECTION BY
BONDED FIXED APPLIANCED

80. • Clinical Management & Maintenance
• Blocks are checked for comfortable occlusion.
• Deep bite correction- twin block lingual component is fixed to permanent
molars.
• Vertical elastics and lingual hooks placed after occlusal blocked removed.
• Appointment should be after 3-4 weeks

81. FUNCTIONAL COMPONENTS
The Twin Block Transpalatal Arch
The Twin Block Lingual Arch

82. The Twin Block Hyrax Appliance
Occlusal inclined planes

83. TWIN BLOCK TRACTION TECHNIQUE
• The cases in which ,
response to functional
correction is poor, the
addition of orthopaedic
traction force may be
considered.
Indications :
• In treatment of severe maxillary
protrution.
• To control vertical growth pattern by
addition of vertical traction to intrude
upper posterior teeth.
• In adult treatment where mandibular
growth cannot assist correction of
severe malocclusion.

85. • The Concorde Facebow-
-Before the development of twin block ,author used
extraoral traction with removable appliance as
means of anchorage.
-A method was developed to combine extraoral and
intermaxillary traction .

86. Concorde facebow helped in restricting maxillary growth, at the same time
encouraged mandibular growth in combination with the functional
appliance.

87. • The labial hook is positioned
extraorally 1cm clear of the lips.
• Traction component are worn only at
night.

88. • Directional control of
orthopedic force-

89. • Dixon et al,Mandibular incisal edge demineralization and caries associated with Twin Block
appliance design, Journal of Orilwitonfics, Vol. 32. 2005, 3 10

90. The use of a Southend clasp on
the upper and lower incisors of
a Twin-block appliance :
• reduces retroclination of the
upper incisors;
• reduces proclination of the
lower incisors;
• applies control to the incisors
which may enhance the skeletal
correction.
Trenouth et al,A randomized clinical trial of two alternative designs of Twin-block Appliance, Journal of
Orthodontics, Vol. 39, 2012. 17-24

91. DESIGNER TWIN BLOCK

92. ADVANTAGES OF TWIN BLOCK

93. Comfort of the patient
Aesthetics
Function
Patient compliance
Facial appearance
Speech
Clinical management
Arch development

94. Vertical control
Facial asymmetry
Age of treatment
Integration with fixed appliances
Treatment of TMJ dysfunctions

95. The effects of Twin Blocks: A prospective controlled
study ( David Ian Lund 1998 AJO)
OBJECTIVE:
This study was designed to investigate the maxillomandibular
skeletal and dentoalveolar changes produced by the Twin Block
appliance compared with those changes experienced by an
untreated control group.

96. • The treatment group consisted of 36 subjects, mean
age of 12.4 years
• The control group consisted of 27 subjects with a
mean age of 12.1 years.
• These patients were observed for a mean time of 1.2
years

97. ANGULAR
MEASUREMENTS

98. LINEAR
MEASUREMENTS

99. Is mandibular growth increased?

100. • statistically significant increase in mandibular length
measured from Articulare-Pogonion, with some forward
movement of Pogonion, both of which are desirable
outcomes of treatment.
• It was not possible to determine whether the increase in Ar-
Pog was due to an increase in mandibular length or a
repositioning of the mandible.
• Baumrind and Korn and Haynes found similar changes in Ar-
Pog. . (1986 AO,AJO 1981)
• However, the Twin Block appliance produced a greater
change over a shorter treatment period

101. Do Twin Blocks restrain maxillary
forward growth?

102. • When forward growth of the maxilla was assessed little change in
SNA was observed thus indicating little maxillary restraint.
• The results do not suggest any significant headgear effect
associated with the Twin Block
• some degree of maxillary restraint might have occurred but was
not detected because of dentoalveolar remodeling disguising the
skeletal effects of the treatment.

103. Is there a beneficial sagittal change?
the forward growth of the mandible does result in a significant change in
ANB thus the severity of the Class II skeletal pattern is reduced.

104. Does tooth tipping contribute greatly
to correction?
There was a significant amount of tipping of the labial segment teeth in
both arches.
• The maxillary incisors were retroclined,
• mandibular incisors were proclined as a result of treatment, which
greatly contributed to correction of the overjet.

105. Does anteroposterior molar
movement aid correction of the
malocclusion?
• A restraining effect on the upper molars was demonstrated to the
extent that there was slight distalization along with a statistically
significant forward movement of the lower molars.
• This change in molar position aids the correction of the disto-
occlusion

106. Do Twin Blocks control the vertical
position of the teeth?
• There was a significantly increased eruption of the lower molars
during treatment after judicious trimming of the bite blocks.
• This not only contributes to overbite reduction and closure of
lateral open bites but also helps with Class II molar correction.

107. The following case report documents a 12-year-old boy
with 11 mm overjet treated by a phase I growth
modification therapy using twin block appliance with
lip pads in a stepwise mandibular advancement
protocol [4],[5],[6] followed by a phase II preadjusted
Edgewise appliance therapy to settle the occlusion and
correct the remaining dental discrepancy.
Management of severe Class II malocclusion with sequential modified
twin block and fixed orthodontic appliances

108. Enhance forward growth of the mandible to improve facial profile and
mandible/cranial base relationship.
Reduce overjet and overbite.
Achieve Class I incisor and buccal segment relationships.
Eliminate lip trap and improve lip competency.
Relieve crowding and align teeth.
Aims of treatment

110. Phase I: Growth modification therapy
• An acrylic twin block appliance with lip pads was given for full-
time wear with an initial mandibular advancement of 6 mm
and interocclusal clearance of 5 mm in the 1st premolar
region.

111. After 6 months, the appliance was activated by advancing the mandible by 5
mm to achieve an edge to edge incisor relationship. The patient was
instructed to turn the maxillary expansion screw once a week and was
reviewed every 4 weeks. Bite blocks were trimmed to achieve proper
vertical eruption of the posterior dentition to reduce the deep bite.
The twin block appliance was removed after 12 months of treatment.
Normal overjet, overcorrected molar relationship, and lip competency were
achieved by phase I orthopedic stage

112. Post functional
appliance
photographs

113. Phase II: Fixed appliance

114. • Utility intrusion arch fabricated using 0.016” × 0.022” SS wire was
placed in the maxillary arch for 3 months for incisor intrusion . The
archwires were subsequently changed to 0.017” × 0.025” stainless
steel wire for torque control.
• Class II elastics were worn full time to maintain the buccal
relationships and overjet.
• Root paralleling was carefully adjusted, and cusp seating was
carried out by vertical elastics at the end of treatment. The total
treatment was completed in 25 months. Upper and lower Hawley's
retainers were given immediately after the fixed orthodontic
appliance was removed

115. Results :
• The post treatment facial profile of the patient demonstrated
noticeable improvement with good facial esthetics, straight facial
profile, and balanced competent lips.
• The intraoral occlusion revealed satisfactory result with
characteristics of well-aligned dentition.
• Overjet and overbite were reduced to 3 mm and 2.5 mm,
respectively.
• Class I canine and molar relationship with good buccal
interdigitation were also achieved.

116. • The twin block appliance due to its acceptability, adaptability, versatility,
efficiency, and ease of incremental advancement without changing the
appliance has become one of the most widely used functional appliances
in the correction of Class II malocclusion. It can eliminate etiologic
factors such as sucking habits and lip trap, restore normal growth, and
reduce the severity of skeletal abnormalities.

117. Effectiveness of treatment for Class II
malocclusion with the Herbst or Twin-block
appliances: A randomized, controlled trial
Kevin O’Brien

118. • The aim of this study was to evaluate the effectiveness of
Herbst and Twin-block appliances for established Class II
Division I malocclusion. The study was a multicenter,
randomized clinical trial carried out in orthodontic
departments in the UK. A total of 215 patients (aged 11-14
years) were randomized to receive treatment with either the
Herbst or the Twin-block appliance.

119. • Treatment with the Herbst appliance resulted in a lower failure-to-complete rate for
the functional appliance phase of treatment (12.9%) than did treatment with Twin-
block (33.6%). There were no differences in treatment time between appliances,
but significantly more appointments (3) were needed for repair of the Herbst
appliance than for the Twin-block.
• There were no differences in skeletal and dental changes between the
appliances;however, the final occlusal result and skeletal discrepancy were better
for girls than for boys. Because of the high cooperation rates of patients using it,
the Herbst appliance could be the appliance of choice for treating adolescents
with Class II Division 1 malocclusion. The trade-off for use of the Herbst is more
appointments for appliance repair. (Am J Orthod Dentofacial Orthop 2003;124:128-
37)

120. DESIGN OF TWIN
BLOCK

121. DESIGN OF HERBST APPLIANCE

122. Conclusions
• Phase I treatment is more rapid with the Herbst appliance, but
overall duration of treatment is similar to that with the Twin-block
• The Herbst appliance is prone to debonding an component
breakage
• There are no differences in the dental and skeletal effects of
treatment

123. Treatment effects produced by the Twin-block appliance
and the FR-2 appliance compared with an untreated
Class II sample
Linda Ratner Toth, and James A. McNamara, Jr AJO 99
• cephalometric study compares the treatment effects produced in
• 40 patients treated with the Twin-block appliance
• 40 children treated with the FR-2 appliance
• 40 untreated Class II controls

124. significant increases in mandibular length were observed in both treated
groups.
The Twin-block achieved an additional 3.0 mm of mandibular length,
whereas the Fränkel 1.9 mm more than did the controls.
No restriction of midfacial growth in either appliance group relative to
controls

125. A increase in lower anterior facial height in both treatment
groups.
more dentoalveolar adaptation was observed in tooth-borne
Twin-block appliance than with the tissue-borne FR-2.

126. The Twin-block and FR-2 samples both showed significant
retroclination and extrusion (eruption) of the maxillary
incisors.
The Twin-block patients exhibited distal movement of the
upper molars; however, there was no extrusion.
Slight lower incisor proclination was noted greater in the
Twin-block group compared with the other .

127. CONCLUSION
Facial harmony and balance are of equal importance to dental
occlusion perfection. One cannot ignore the importance of
orthopaedic techniques in achieving these goals by growth
guidance during the formative years of facial and dental
development.
The integration of orthodontic and orthopaedic techniques offer a
new initiative in restoring facial balance.

128. REFERENCES
• Tan et al,A preliminary report of a new design of cast metal fixed twin-block
appliance, Journal of Onhodottíics, Vol. 34. 2007, 213-219
• Woodside DG (1977) The activator. In: Graber TM, Neumann B, editors. Removable
Orthodontic Appliances. Philadelphia: Saunders; pp. 269-336.
• McNamara JA. Neuromuscular and skeletal adaptations to altered function in orofacial
region. AJO 1973)
• The twin block technique A functional orthopedic appliance system
• WJ Clark - American Journal of Orthodontics and Dentofacial …, 1988
• Design and management of Twin Blocks:reflections after30 years of clinical use
William Clark
• Doshi et al, Effective temporomandibular joint growth changes after stepwise and
maximum advancement with Twin Block appliance, Journal of the World Federation of
Orthodontists 3 (2014) e9-e14
• Dixon et al,Mandibular incisal edge demineralization and caries associated with Twin
Block appliance design, Journal of Orilwitonfics, Vol. 32. 2005, 3 10
•

129. • Trenouth et al,A randomized clinical trial of two alternative designs of
Twin-block Appliance, Journal of Orthodontics, Vol. 39, 2012. 17-24
• The effects of Twin Blocks: A prospective controlled study ( David Ian
Lund 1998 AJO)
• Management of severe Class II malocclusion with sequential modified
twin block and fixed orthodontic appliances
• Effectiveness of treatment for Class II malocclusion with the Herbst or
Twin-block appliances: A randomized, controlled trial
• Treatment effects produced by the Twin-block appliance and the FR-2
appliance compared with an untreated Class II sample
• Linda Ratner Toth, and James A. McNamara, Jr AJO 99