Twin block

GOOD MORNING
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 INTRODUCTON
 DEVELOPMENT OF TWIN BLOCKS
 APPLIANCE DESIGNS & CONSTRUCTIONS
 TWIN BLOCK TECHNIQUE
 MODE OF ACTION
 TREATMENT BY TWIN BLOCK TECH
 CONCLUSION
 REFERENCESwww.indiandentalacademy.comwww.indiandentalacademy.com

NECESSITY IS THE MOTHER OF INVENTION
 First twin block app : 1977, to 8ys old patient.
 First patient : Colin Gove.
 First fabricated : Jim Watt.

 ““Orthodontics and Dentofacial Orthopedics”Orthodontics and Dentofacial Orthopedics”
which consists of two terms both of which arewhich consists of two terms both of which are
important in order to describe the treatmentimportant in order to describe the treatment
given to improve the dental and orthopedicgiven to improve the dental and orthopedic
relationships in the stomatognathic system alongrelationships in the stomatognathic system along
with a aim to obtain a balanced facial form.with a aim to obtain a balanced facial form.
 After almost a centaury of development ofAfter almost a centaury of development of
functional appliances it was surprising that thefunctional appliances it was surprising that the
appliances were still bulky and were not utilizingappliances were still bulky and were not utilizing
the forces of occlusion as a functionalthe forces of occlusion as a functional
mechanism for correction of malocclusion.mechanism for correction of malocclusion.

 On 7th September 1977,On 7th September 1977, Dr.Dr.
William J. ClarksWilliam J. Clarks
developed Twin Blocks. Adeveloped Twin Blocks. A
natural progression in thenatural progression in the
evolution of functionalevolution of functional
appliance therapy,appliance therapy,
representing a significantrepresenting a significant
transition from one piecetransition from one piece
appliance that restricts theappliance that restricts the
normal function to a twinnormal function to a twin
appliance that promotesappliance that promotes
normal function. The goal ofnormal function. The goal of
twin block therapy was totwin block therapy was to
produce a technique thatproduce a technique that
could maximize the growthcould maximize the growth
response to functionalresponse to functional
mandibular protrusion bymandibular protrusion by
using an appliance systemusing an appliance system
that is simple, comfortablethat is simple, comfortable
and aesthetically acceptableand aesthetically acceptable
to the patients.to the patients.

PHILOSOPHY BEHINDPHILOSOPHY BEHIND
TWIN BLOCKTWIN BLOCK
THERAPYTHERAPY

OCCLUSAL INCLINED PLANEOCCLUSAL INCLINED PLANE
 According to Clarks theAccording to Clarks the
occlusal inclined planesocclusal inclined planes
were the fundamentalwere the fundamental
functional mechanism forfunctional mechanism for
the natural dentition. Andthe natural dentition. And
the inclined planes playthe inclined planes play
an important role inan important role in
determining relationshipdetermining relationship
of the teeth as they erupt.of the teeth as they erupt.
The aim of the inclinedThe aim of the inclined
planes of the bite blocksplanes of the bite blocks
in twin block is to modifyin twin block is to modify
these inclined planes andthese inclined planes and
cause more favorablecause more favorable
growth pattern.growth pattern.

USE OF MASTICATORY FORCEUSE OF MASTICATORY FORCE
 One major advantageOne major advantage
in twin blocks was thatin twin blocks was that
it could be worn 24it could be worn 24
hours, hence thehours, hence the
masticatory forced canmasticatory forced can
be transmitted via thebe transmitted via the
appliance to theappliance to the
dentition from wheredentition from where
they are transmitted tothey are transmitted to
the bony trabaculaethe bony trabaculae
according to wolfs law,according to wolfs law,
hence influencing thehence influencing the
rate of growth and therate of growth and the
trabaculae structure oftrabaculae structure of
the supporting bone.the supporting bone.www.indiandentalacademy.comwww.indiandentalacademy.com

DEVELOPMENT OFDEVELOPMENT OF
TWIN BLOCKTWIN BLOCK

7th September 19777th September 1977
NameName :-:- Colin GoveColin Gove
Age / SexAge / Sex :- 7yrs 10 months / Male:- 7yrs 10 months / Male
Chief ComplaintChief Complaint :- Luxated upper central incisor:- Luxated upper central incisor
On ExaminationOn Examination :- Class II div 1 malocclusion:- Class II div 1 malocclusion
with a 9mm overjet and a midline shift to right.with a 9mm overjet and a midline shift to right.
TreatmentTreatment :- The tooth was reimplanted but due:- The tooth was reimplanted but due
to class II; lower lip was trapped lingual to theto class II; lower lip was trapped lingual to the
luxated tooth causing mobility and rootluxated tooth causing mobility and root
resorption to prevent this the appliance with aresorption to prevent this the appliance with a
Occlusal plane which could place the mandibularOcclusal plane which could place the mandibular
forward into a edge to edge bit was made later aforward into a edge to edge bit was made later a
fixed treatment was done. Later the reimplantedfixed treatment was done. Later the reimplanted
tooth was crowned and a stable result wastooth was crowned and a stable result was
obtained at age of 25 years.obtained at age of 25 years.

Before
Treatment
IOPA
Showing
Luxated 11
Post
Treatment
IOPA
Showing An
Endodontic
Pin To
Stabilize 11
Different Stages Of
Treatment Using Twin Block
Combination Therapy With
Fixed Appliance In Later
Stagewww.indiandentalacademy.comwww.indiandentalacademy.com

Comfort
Esthetic
Function
Patient compliance
Facial appearance
Speech
Clinical managementwww.indiandentalacademy.comwww.indiandentalacademy.com

Arch development
Mandibular repositioning
Vertical control
Facial asymmetry
Safety & efficiency
Integration with fixed appliance
Treatment of TMJ dysfunctionwww.indiandentalacademy.comwww.indiandentalacademy.com

CASE SELECTIONCASE SELECTION

 Class II div 1 with a good arch form.Class II div 1 with a good arch form.
 Lower arch uncrowdedLower arch uncrowded
 Upper arch aligned.Upper arch aligned.
 Overjet 10-12 mm and a deep bite.Overjet 10-12 mm and a deep bite.
 Full unit distal occlusion.Full unit distal occlusion.
 On models when the lower model is advanced toOn models when the lower model is advanced to
edge to edge bite the distal occlusion should getedge to edge bite the distal occlusion should get
corrected.corrected.
 Patient should be growing actively preferablyPatient should be growing actively preferably
should be in pubertal growth spurt.should be in pubertal growth spurt.
 VTO positive.VTO positive.

STAGES OFSTAGES OF
TREATMENTTREATMENT

Treatment with twin block is divided intoTreatment with twin block is divided into
two stages:-two stages:-
Stage 1 : active phaseStage 1 : active phase
Stage 2 : support phaseStage 2 : support phase

Stage 1 : active phaseStage 1 : active phase
 Sagital correction is achieved first by placing the twinSagital correction is achieved first by placing the twin
block along with which the vertical correction is obtainedblock along with which the vertical correction is obtained
by selective trimming of the bite block of the posteriorby selective trimming of the bite block of the posterior
teeth. While trimming it is made sure not to trim moreteeth. While trimming it is made sure not to trim more
then 1-2mm so as to not allow the tongue to come inthen 1-2mm so as to not allow the tongue to come in
between the teeth and the bite block. For class II withbetween the teeth and the bite block. For class II with
deep overbite the upper bite block is trimmeddeep overbite the upper bite block is trimmed
occlusodistally allowing the teeth to erupt. At eachocclusodistally allowing the teeth to erupt. At each
subsequent visit the block is trimmed progressively tosubsequent visit the block is trimmed progressively to
allow the lower post to erupt, till al the acrylic is removed.allow the lower post to erupt, till al the acrylic is removed.
The leading edge of the inclined planes should not beThe leading edge of the inclined planes should not be
trimmed so as to get a adequate functional Occlusaltrimmed so as to get a adequate functional Occlusal
support. In case of open bite the posterior Occlusal bitsupport. In case of open bite the posterior Occlusal bit
blocks are not trimmed.blocks are not trimmed.
 The aim in this stage is to achieve a class I occlusionThe aim in this stage is to achieve a class I occlusion
with corrected overbite and overjet and a three pointwith corrected overbite and overjet and a three point
Occlusal contact with incisors and molars.Occlusal contact with incisors and molars.
 This stage lasts for aroundThis stage lasts for around 6-9 months6-9 months..

Stage 2 : support phaseStage 2 : support phase
The aim is to maintain the correctedThe aim is to maintain the corrected
incisor relation till the buccal segment isincisor relation till the buccal segment is
fully interdigitated. The upper removablefully interdigitated. The upper removable
appliance is fitted with a anterior inclinedappliance is fitted with a anterior inclined
plane to engage the lower incisor andplane to engage the lower incisor and
canines and the lower twin block is left outcanines and the lower twin block is left out
in this stage. Full time wear of thein this stage. Full time wear of the
appliance is necessary in this stage toappliance is necessary in this stage to
achieve proper bony remodeling toachieve proper bony remodeling to
support the corrected occlusion.support the corrected occlusion.
This stage lasts for aroundThis stage lasts for around 3-6 months3-6 months..

RetentionRetention
 After the treatment a appliance with upper inclined planeAfter the treatment a appliance with upper inclined plane
or a Rick-A-Nator is given and the use is graduallyor a Rick-A-Nator is given and the use is gradually
reduced.reduced.
 Rick-A-Nator ApplianceRick-A-Nator Appliance -This fixed orthodontic-This fixed orthodontic
appliance is the treatment of choice since it is fixed. Theappliance is the treatment of choice since it is fixed. The
Rick-A- Nator Appliance are utilized to hold the mandibleRick-A- Nator Appliance are utilized to hold the mandible
in a forward position and also to help erupt the bicuspidsin a forward position and also to help erupt the bicuspids
to complete the orthopedic correction of the overbite.to complete the orthopedic correction of the overbite.
 It is vital that the total treatment time for the active phaseIt is vital that the total treatment time for the active phase
with the Twin Block and the support phase with the Rick-with the Twin Block and the support phase with the Rick-
A-Nator be a minimum of 15 to 18 months to allow forA-Nator be a minimum of 15 to 18 months to allow for
permanent muscular, skeletal and dental changes to bepermanent muscular, skeletal and dental changes to be
accomplished. It is required after occlusion is fullyaccomplished. It is required after occlusion is fully
established. During retention period appliance wear canestablished. During retention period appliance wear can
be gradually reduced to nighttime wear.be gradually reduced to nighttime wear.www.indiandentalacademy.comwww.indiandentalacademy.com

BITE REGISTRATION
STANDARD TWIN BLOCK
OCCLUSAL INCLINED PLANES

BITE REGISTRATION
 It is a crucial factor in design & construction.
 It determines the degree of activation built in to the
appliance.
 The degree of activation should stretch the muscles of
mastication sufficiently to provide the possitive
propriocepive response.
 Consideration is given to facial growth pattern.

BITE REGISTRATION
STEP WISE ADVANCEMENT Vs SINGLE STEP ADVANCEMENT
A study was done to identify the pattern of bone formation
in tmj in response to the step wise mandibular advancement
compared to single step advancement with fixed functional
appliances .
They concluded that step wise advancement produces more
skeletal effects than single advancement and more
prominent effect with step wise advancement was found
in the glenoid fossa compared with the condyle.
( Semin Orthod 2003:9:41-46) www.indiandentalacademy.comwww.indiandentalacademy.com

BITE REGISTRATION IN TWIN BLOCK TECH
VERTICAL ACTIVATION.
AND
CONTROL OF VERTICAL DIMENSION.

BASIC COMPONENTS
CONTROVERSIES REGARDING LABIAL BOW

DELTA CLASP
BALL END CLASP &BASE PLATE

OCCLUSAL INCLINED PLANE
 Active component of twin block .
 Occlusal forces are in the range of 400 – 500gms

STAGE I : ACTIVE PHASE ( 6-9 MONTHS)
STAGE II : SUPPORTIVE PHASE ( 3-6 MONTHS)
RETENTION : UPPER ANT INCLINED PLAN ( 9MONTHS)

STAGE I : ACTIVE PHASE ( 6-9 MONTHS)

STAGE II : SUPPORTIVE PHASE ( 3-6 MONTHS)

 It can be done by cold cure acrylic or preformed
heat cure block.
 No acrylic is added to the lower inclined plan.

 Central control of adaptive response &Neuromuscular &
skeletal adaptations.
( McNamara , 1980 )
 Adaptation of bone growth in response to functional
stimulus.
( Wood side et al , 1987 )

 A comparison of twin block response with animal
experiments.
(Harvold)
 A review of paradigm of genetic control
( Petrovic et al , 1981 )
 Improved clinical use of twin block & herbst
as a result of radiating viscoelastic tissue
forces on the condyle & fossa in treatment &
long term retention : growth relativity.
( Voudouris et al :ajo do:2000:117:247-66.)

1.TREATMENT OF CLASS I DIV I WITH DEEP BITE.
D. MANAGEMENT OF DEEP OVERBITE.
A. BITE REGISTRATION.
EXACTO BITE
PROJET BITE GUAGE
B. TEMPORARY FIXATION OF TWIN BLOCK
C. COMFORT ZONE

2. TREATMENT IN MIXED DENTITION

3.COMBINATION THERAPY IN PERM DENTITION
INTEGRATION OF TWIN BLOCK WITH FIXED APPLIANCES

4. TWIN BLOCK TRACTION TECH
 In the treatment of severe maxillary protrusion.
 To control vertical growth pattern.
 To intrude upper posterior teeth.
 In adult treatment where mandibular growth
cannot assist correction of severe malocclusion.
CONCORDE FACEBOW

5.TREATMENT OF ANT OPEN BITE
 Etiology.
 C / F of ant open bite.
 Appliance modifications.

6. TREATMENT OF CLASS II DIV II MALOCCLUSION
 C / F .
 Bite registration.
 Appliance design.
Sagittal appliance

7. TREATMENT OF CLASS III MALOCCLUSION
Reverse twin blocks

9. MANAGEMENT OF CROWDING &
EXTRACTION THERAPY
 Extraction & Functional therapy are contra indicatory terms.
 Indications in certain cases.
a. Severe crowding.
b. Vertical growth pattern with crowding.

10. TREATMENT OF FACIAL ASYMMETRY
SAGITTAL TWIN BLOCK IS THE APPLIANCE OF CHOICE.

11.MAGNETIC TWIN BLOCKS
 To accelerate correction of arch relationship.
 To encourage increased occlusal contacts on the bite blocks
& to maximise favourable forces applied to correct
malocclusion.
 Attracting magnets : Samarium cobalt & Neodynium
boron.

11.MAGNETIC TWIN BLOCKS
Author has used magnets in FIVE different clinical situations
1. Cl II div 1 with large overjet.
2. Mild Cl II buccal segment relationship.
3. Mild Cl II div 1 with overjet 7mm.
4. Unilateral Cl II adult patient with TMD.
5. Skeletal Cl III with persistent cross bite failed to resolve with
conventional mechanics.
6. Treatment of facial asymmetry.

12.TWIN BLOCK IN TMJ THERAPY
 C / F.
 Diagnosis.
 Goals of TMJ therapy.
 Appliance design.
 Stages of treatment : 1.Sagittal development
2.Functional Repositioning
3.Vertical development
 Biofinisher.

13. FIXED TWIN BLOCKS

13. FIXED TWIN BLOCKS
 Advantages of fixed appliances
 Esthetic appliance design.
 Stages of treatment.
1. Interceptive treatment & arch development by the Wilsons
modular appliance system.
2. Orthopaedic treatment by fixed twin blocks.
3. Detailed orthodontic correction by fixed appliance.

Twin Block is versatile removable functional appliance
used to treat various types of malocclusions.
Having knowledge about the Twin Block and its various
modifications with proper case and appliance selection
successful results can be obtained.

1. Twin Block Functional Therapy,
by William J Clark.
2. Orthodontics & Dentofacial Orthopedics
by McNamara & Brudon.
3. Dentofacial Orthopedics with Functional Appliances
by Graber , Rakosi & Petrovic.
4. Orthodontics Current Principles & Techniques
by Graber , Vanarsdall.
5. Removable Orthodontic Appliances
by Graber & Neumann.
6. Am J Orthod Dentofacial Orthop :2000:117:247-66.
7. Semin Orthod : 2003:9: 41-46.www.indiandentalacademy.comwww.indiandentalacademy.com

Twin block

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