Transpalatal arch for molar rotation

AN IMPROVED TRANSPALATAL
ARCH DESIGN FOR
SYMMETRICAL MOLAR
DEROTATION
www.indiandentalacademy.com

PART---I
COMPARISON 0F MOMENTS AND FORCES
DELIVERED BY TWO BAR DESIGNS
--ZACHRISSON TYPE
--GOSHGARIAN TYPE

USES OF TRANSPALATAL ARCHES
1. ESTABLISH AND MAINTAIN ARCH WIDTHS
2. DEROTATE UNILATERALLY OR BILATERALLY
ROTATED MOLARS
3. REINFORCE POSTERIOR ANCHORAGE
4. CORRECT UNILATERAL CROSSBITE
5. MAXILLARY EXPANSION
6. BUCCAL ROOT TORQUE IN MOLARS
7. CORRECT M-D ASYMMETRIESwww.indiandentalacademy.com

DESIGN VARIATIONS-
1.Goshgarian type(traditional type)—GTPB
2.Quad helix
3.NI-TI palatal expander
4.NI-TI molar rotator
5.Burstone`s lingual arches
6.Wilson`s 3D lingual appliances
7.Zachrisson type---ZTPB

GTPB
0.036`` Stainless steel with central loop
----directed mesially /distally
ZTPB
0.036``blue elgiloy with three loops
--larger& longer central loop
--two distally directed smaller loops on either side
symmetricallywww.indiandentalacademy.com

ZTPB ----- greater length of wire (decrease strength ,
increase springiness,
increase range )
----- lower load deflection rate
----- greater flexibility
----- constant and predictable forces
Blue Elgiloy has excellent formability ,slightly higher stiffness
than stainless steel after heat treatment
Stainless steel and heat treated Elgiloy have similar modulus of
elasticity

APPLIANCE DESIGN
Both measured 53mm between ends
ZTPB
Extended length ---89mm
Central loop height---9mm
width---12mm
Smaller loop height---5mm
width---4mm
GTPB
Extended length---61mm
Middle loop height---7mm
width---6mmwww.indiandentalacademy.com

BOTH MADE TO BE PASSIVE IN ALL THREE PLANES
STANDARDISED INTERMOLAR WIDTH -–34mm
PALATAL VAULT HEIGHT—13mm
ZTPB`s HEATTREATED FOR STRESS RELIEF (15 seconds)
PASSIVITY MEASURED USING A MEASURING
APPARATUS AT ZERO DEGREE INCLINATION.

MEASURING APPARATUS:
Computer based strain gauge system
Two units representing rt. & lt. Molars with lingual attachments
Attachments placed vertically,parallel & facing each other on same
plane
Attachments fastened to movable clutches with strain gauge sensors
SAGITTAL AND HORIZONTAL FORCES RECORDED BY
FOUR FORCE RECORDERS AND MOMENTS RECORDED BY
TWO MOMENT RECORDERS

Each end activated by 10mm
Fully active bars inserted into lingual attachments of
measuring apparatus and 3 measurement steps were
taken at zero,five & ten degrees of deactivation.

Moments in clockwise direction---``+”ve
anticlockwise direction---``-” ve
Palatal directed horizontal forces---``-”ve
Buccal directed horizontal forces---``+” ve
Mesial directed sagittal forces---``-” ve
Distal directed sagittal forces---``+” ve

RESULTS
BOTH BARS PRODUCE LARGEST MOMENTS IN FULL
ACTIVATION
GTPB ----- PRODUCE HIGHER MOMENTS
----- PRODUCE INCREASING CONTRACTIVE FORCES
----- SIGNIFICANT SAGITTAL FORCES
ZTPB ----- INSIGNIFICANT HORIZONTAL / SAGITTAL FORCES

DISCUSSION
ACCORDING TO BURSTONE GEOMETRY `5`:
“ THE SAGITTAL FORCE WILL BE MESIAL WHERE THE
MOMENTS FOR DEROTATION FOR MESIALLY ROTATED
MOLARS IS LARGER ”
ACCORDING TO BURSTONE GEOMETRY `6`:
“ DURING DEROTATION OF SYMMETRICALLY ROTATED
MOLARS,EQUAL AND OPPOSITE MOMENTS WILL BE
PRODUCED WITHOUT CREATING SAGITTAL FORCES ”
SIDE EFFECTS
SAGITTAL (M-D)

GEOMETRY `6`
GEOMETRY `5`

MOST IMPORTANT IS CONTRACTION PRODUCED BY
PALATALLY DIRECTED HORIZONTAL FORCES.
GTPB
AT FULL ACTIVATION,CENTRAL LOOP OPENS ITSELF
FOLLOWING DEROTATION,THE LOOPS CLOSE
-----------INITIAL HORIZONTAL EXPANSIVE FORCES
WITH INCREASING DEACTIVATION,MAGNITUDE OF
CONTRACTIVE FORCES INCREASE
HORIZONTAL

IN ZTPB, DISTALLY DIRECTED LOOPS INCREASE FLEXIBILITY
& MAKES ATTACHMENTS EASIER .
DURING ACTIVATION, CENTRAL LOOP OPENS WHILE
ADDITIONAL LOOPS CLOSE__`` BAR IS ACTIVE TILL THE
LOOPS COME TO THEIR ORIGINAL SHAPES ”
WHEN CENTRAL LOOP CLOSES DURING DEACTIVATION,
SMALLER LOOPS OPEN THEMSELVES

MOST CONTRACTIVE FORCES PRODUCED WITH TEN
DEGREES DEACTIVATION
TO COMPENSATE FOR THIS, MESIALLY DIRECTED
LOOPS SHOULD BE USED AND THE TPA SHOULD
BE MADE TOTALLY PASSIVE AFTER MOLAR
DEROTATION.

PART II
CLINICAL UPPER MOLAR DEROTATION
INTRODUCTION:
RICKETT`S--- IN IDEAL OCCLUSION , A LINE DRAWN
BETWEEN M-L AND D-B CUSPS OF MAX. I MOLARS SHOULD
TRANSECT DISTAL THIRD OF CANINE OF OPPOSITE SIDE
90% CLASS II MOLAR RELN. IS DUE TO MAX. I MOLAR
ROTATION
ROTATION OFTEN OCCURS AROUND AN AXIS LINGUAL TO
THEIR CENTRAL FOSSAwww.indiandentalacademy.com

BY CORRECTION OF THESE ROTATIONS 1-2 mm OF ARCH
LENGTH PER SIDE AND PARTIAL CLASS II CORRECTION
CAN BE ACHIEVED
ZTPB---CLINICAL EFFECTIVENESS
BILATERALLY ROTATED MAX. MOLARS WERE DEROTATED
USING ZTPB
OCCLUSOGRAMS WERE DRAWN BEFORE & AFTER
SATISFACTORY DEROTATION

TWO MEASUREMENTS MADE TO EVALUATE
DEGREE OF ROTATION:
1. Angle between a line passing thro` molar buccal
surface and midsagittal line
2. Angle between a line thro` M-B & M-P cusps and
midsagittal plane

CASE REPORTS

Transpalatal arch for molar rotation

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Transpalatal arch for molar rotation