Twin block 2 /certified fixed orthodontic courses by Indian dental academy

TWIN BLOCK
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


1

Twin block technique


2

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Treatment of Class II div I.
Treatment in mixed dentition.
Twin block traction technique.
Treatment of ant. open bite
Treatment of Class II div II.


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Treatment of Class III.
Magnetic twin block
Twin block for TMJ therapy.
Fixed twin block.


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Treatment of Class II Div I
Deep Bite
Bite registration-Project Bite Gauge.
 On an average-5-10 mm
(70% protrusive path) .
 Reactivation of appliance.



5

Deep Bite
Appliance design
-inclined planes must
be clear of the lower
molars .
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Deep Bite
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1.

2.

Temporary fixation of twin block.
Appliance may be fixed using cement
on the tooth bearing areas.
Bonded directly on clasps-esp. on
deciduous molars


7

Deep Bite


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Deep Bite
Management of deep bite-this is achieved by trimming the occlusal
block, so as to encourage eruption of
the lower molars


Elastic separators
Trimming occlusodistally

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

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Deep Bite


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Deep Bite
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Intergingival height-used to establish
correct vertical dimension.


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Deep Bite
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Comfort zone-17-19 mm.
This is used as a guide to establish the
correct vertical dimension during
treatment.


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Deep Bite
Reactivation of twin block-In case of larger overjet.
-Full correction not achieved with initial
activation.
-Growth is less favourable.
-In adult treatment.
-In TMJ therapy
-Restricted protrusive pathway.
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Deep Bite


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Deep Bite
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Extending the ant.
incline of upper twin
block
Preformed inclined
wedges may be
used.


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Treatment in Mixed Dentition


Skeletal discrepancies are not
delayed until the permanent dentition.

1.

Prominent upper incisors.

2.

Early treatment of crowding.

17

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Bite registration-same…

Appliance design-modified to meet the
requirement of mixed dentition
- limited by decd. teeth
- unfavourable contour

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1.
2.
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C –clasps are commonly used –
Temporary fixation.
Grind retention groove.
Ball end clasps
Synthetic crown contours


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21

Twin block Traction Technique



1.
2.
3.

In most cases ,full functional
correction can be achieved with twin
block alone.
In minority of the casesSevere maxillary protrusion.
To control vertical growth pattern.
Adult treatment.

22

The Concorde Facebow-Before the dev. of twin block ,author
used extraoral traction with removable
appliance as means of anchorage.


-A method was developed to combine
extraoral and intermaxillary traction .

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The labial hook is
positioned
extraorally 1cm
clear of the lips.
Traction component
are worn only at
night.
Careful selection of
case is very
essential


25

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Concorde facebow helped in restricting
maxillary growth, at the same time
encouraged mandibular growth in
combination with the functional
appliance.
Patient comfort and acceptance was
similar to the conventional facebow.

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Directional control of
orthopedic force-


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Treatment of Ant. Open Bite
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May be due to -skeletal.
-soft tissue.
Airway obstruction.
Early treatment –helpful in controlling
functional imbalance
Prognosis-extent of skeletal/soft tissue
- growth pattern

29

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Pitfalls in Treatment –
Necessary to be attentive to avoid
overeruption of 2nd molars behind the
appliance.


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Trimming of the upper twin block


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Bite registration-Sagittal activation-two step activation to
be done in cases with increased jet.
-Vertical activation-4mm interincisal
clearance, so as to open bite beyond
the free way space
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Appliance design
Vertical control-increase
thickness of block.
-occlusal rest on 2nd
molars
- no acrylic on ant. teeth.

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Closing Ant. Open
bite
- Palatal spinner.
- Tongue guard.
- Labial bow.
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Intra oral traction .
-This may be used to accelerate bite
closure-alternative to high pull
headgear.
-Idea was taken from Dr Mills, who used
elastics to maintain occlusal contacts.
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Intrusive effect of the blocks is
reinforced by vertical elastics.
Elastics may be worn at night/full time.
Additional advantage of increasing
occlusal contact on the inclined planes.
Magnets can also be used for the same
purpose.

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38

Treatment of Class II Div II
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Retroclined upper incisors are
responsible holding the mandible.
Twin block aims at unlocking the
malocclusion by releasing the mandible
from entrapped position.


39

Bite registration
-Bite is taken with incisors in edge-edge.


-These pt. usually have a deep bite, so
they require more vertical development.
-However amount of sagittal
advancement is limited

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Appliance design
Sagittal Dev.-formerly sagittal appliances
were used (Witzig and Sphal 1987).


-Two sagittal screws are placed in the
horizontal plane and angled along the
line of buccal segment.

43

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Can be used for
both upper and
lower arches.


44

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Combined
transverse and
sagittal development


45

Treatment of Class III


Functional
correction of Class
III malocclusion can
be achieved by
simply reversing the
angulation of the
inclined planes.


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Bite registration-

-Differs from Class II malocclusion.
-2mm interincisal clearance in full
retruded position.

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Appliance design-sagittal design is
usually made.
-combination of
transverse and
sagittal.
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One important point-position of the
condyles.
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Another
modification-lip pads
may be used to
support the upper lip
clear of the incisors.


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Reverse pull facial
mask
As an additional
component to
advance the maxilla
by elastic traction


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52

Magnetic Twin Block
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Used to accelerate correction of the
arch relationship.
Two types-samarium cobalt.
-neodynium boron.
Vardimon et al 1989-90-carried out
various animal experiments in
mandibular advancement

53

Magnetic Twin Block




Author modified the
twin block by
addition of attracting
magnets .
Magnets are placed
on to the inclined
planes.


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Magnetic Twin Block
Attracting magnets
-Increase activation
- Increase frequency
-Increased force of contact
 Repelling magnets
-Less mechanical activation.
-Additional stimulus.



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TMJ Therapy
Case history & diagnosis-Full case history –cause and effect
relationship of occlusal disharmony and
mandibular displacement to pain .


-

Radiographic examination of the
TMJ.

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TMJ Therapy
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-

Timing of the clickEarly opening click-22mm
Midopening click-22-35mm
Late opening click-35mm


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TMJ Therapy
Goals of TMJ therapy-relieve pain by distal displacement
-restrain muscles to healthy pattern.
-recapture disc by advancing mandible.
-move teeth causing occlusal imbalance.
-increase the vertical dimension.
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TMJ Therapy
Stages of treatmentI-sagittal
development-

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TMJ Therapy
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II

Functional repositioning
Pain relieved immediately
Muscles are restrained
Disc is recaptured

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TMJ Therapy
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III

Vertical development

Trimming the upper blocks
Vertical traction
Twin block biofinisher

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TMJ Therapy
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Twin block
biofinisher-


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TMJ Therapy


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Fixed Twin Blocks
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1.
2.
3.

Increase control by the operator
Limited indicationsGrowth status of the pt.
Pt. cooperation.
One phase treatment is planned.

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Fixed Twin Blocks


1.
2.

3.

Three distinct phasesFirst –arch development.
Second –orthopaedic treatment with
fixed functional twin block system.
Third – detailed orthodontic treatment

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Fixed Twin Blocks
Functional
componentsTwin Block
Transpalatal Arch


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Fixed Twin Blocks
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Twin block lingual
arch


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Fixed Twin Blocks
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Twin Block Hyrax
Appliance


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Fixed Twin Blocks
Clinical Management & Maintenance
-appliance is tried in mouth –bite is checked
-Once cemented-if correct forward posture is
not achieved
a- lower appliance may be removed and
trimmed
b- provision of Class II elastics
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Fixed Twin Blocks
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Appointment should be after 3-4 weeks.
Support phase-anterior inclined plane is
constructed.
-standard lower appliance
Comprehensive fixed appliance phase.


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Fixed Twin Blocks
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1.
2.
3.

Some disadvantagesBlocks may become loose.
Control of vertical dimension is limited.
Compromised oral hygiene.


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7th IOS PG conventionDr Pradip Shetey
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The mandibular -first molar and adams
clasp is fabricated on it. A hook is
fabricated and soldered on to the adams
clasp.
In the maxillary arch, the elastics are
engaged onto the U loop of the labial
bow.
A Class II elastic force in the range of 70
to 80 gms per side

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1. Posture the mandible forward even
during sleep.
2.Encourages mandibular growth by
stimulating the retrodiscal pad of the TM
joint . (Petrovic 1977)
3.Uprights the proclined maxillary incisors
in a class II div I malocclusion

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4.. Reduces the treatment time
5. Only a simple modification is required
to engage the classs II elastics in
comparison to the use of concorde face
bow or magnets.
6. Good patient comfort and acceptance.
7. Can be used 24 hours

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Other Modifications


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Other Modifications


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Recent Studies


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The Effect of Twin blocks
-David Ian et.al. AJO1998
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Prospective controlled study.
Sample size -36 -19 males
-17 females
Mean age of 12.4yrs and 0.9 yrs.
Control group-27 -13 males
-14 females
Mean age of 12.1 yrs.

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Skeletal –
-a mean forward growth /repositioning of
mandible of 2.4mm.
-increase in SNB.
-no significant maxillary restraint.
-Increase in lower ant. face height
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80

Dental-overjet reduction -10.8 retroclination
-7.9 proclination
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-buccal segment correction.


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Very effective in reducing overjet.
This mainly due to dentoalveolar
effects.
Significant increase in the SNB.
Attempt to modify .


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Treatment Effects of the Twin
Block Appliance: A Ceph. study

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-- Christine Mills & McCulloch
-AJO 1998
Clinical prospective study
Purpose was to evaluate
cephalometrically the treatment effects
of the Twin Block appliance.


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Sample size -28 -11 boys
-17 girls
 Mean age was 9yrs 1 month.
 The criteria for selection-skeletal class II with positive VTO.
-ANB-more than 5
-full cusp Class II & end on or greater.
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Active treatment 6-15 months.
Control group included 28 untreated
persons with class II malocclusion
obtained from Burlington Growth Centre
at the University of Toronto.


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-

Appliance was slightly modified
- Acrylic labial bow.
- Elastic hooks.
31 Cephalometric variables were used
13 showed a significant differences.

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ResultsMandibular unit length (Co-Gn)-6.5mm
increase as compared to 2.3mm.
Increase in the SNB by 1.9 as
compared to 0.3
Headgear effect was also observed-0.9
decrease in the SNA .

87

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Same was observed dentally-1mm
distalization on upper molars in contrast
to 0.3 mm forward migration.
Lower incisors tipped 5.2 as compared
to 1.4.
Lower molars moved mesially 1.4 as
compared to 0.2 mm mesial movement.

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Overall reduction of overjet by 5.6mm
Nearly 2/3 of it could be accounted for
by the forward growth of mandible.
Further follow up studies are underway
to assess the long term stability .

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Posttreatment changes after
successful correction of class II
malocclusion with Twin Block
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-AJO 2000
Sample size -26 sample-11 males
-15 females
Control group was again selected and
matched for age, sex, vertical facial type.
24 out of 28 control which were used
earlier.

90

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31 variables were used-25 showed
statistically significant difference.
Results –
There was a overall increase of 6.5mm
over 36 months (2mm per year).
Control group showed -6.7mm over 34
months(2.4mm)

91

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The Twin Block group showed some
relapse in dental changes
Upper incisors uprighting 1.5 and labial
proclination of 0.8 –overjet reduction of
1mm.
Less mesial migration of lower molars
as compared to the control group.

92

Cephalometric evaluation of Twin Block in
treatment of class II Div I malocclusion with
matched normative data

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-M.J.Trenouth AJO 2000
Aim-to compare ceph. changes in a group
of successfully treated pt. matched for
age, sex, and treatment time from
published normative data.
Sample -30 pts. 14 -males
16-females

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Results-reduction of overjet by 7mm
-significant reduction in upper incisor
angulation
-no significant change in lower incisor
angulation.



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Statistically significant reduction in ANB
angle-mainly due to increase in SNB.


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Treatment timing for Twin Block therapy
AJO 2000 TizianoBaccetti
-Lorenzo Franchi
-Linda Toth
- James Mcnamara

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


Cephalometric study conducted to
evaluate skeletal and dental changes
induced by twin block with two different
groups ,treated at different skeletal
maturity stages.
Group 1-21 –mean age 9yrs 11 months
Group 2-15 –mean age 12yrs 11 months

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-Lorenzo Franchi
-Linda Toth
- James Mcnamara

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Group 1-peak in the growth was not
achieved
Group 2-during or slightly after onset of
pubertal growth spurt.
Results –group 2 produced more
favourable results.


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-Lorenzo Franchi
-Linda Toth
- James Mcnamara

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Greater skeletal contribution to molar
correction
Lager increments in total mandibular
length.


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Advantages of Twin Block
Appliance
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Comfort
Esthetics
Function
Pt .compliance
Facial appearance.
Speech

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Appliance
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Clinical management.
Arch dev.
Vertical control
Facial asymmetry
Safety and efficiency
Age of treatment.

100

Appliance

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Integration with fixed appliance
Treatment of temporomandibular joint
dysfunction.


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102

Twin block 2 /certified fixed orthodontic courses by Indian dental academy

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