Efficiency of newer generation edge wise applience /certified fixed orthodontic courses by Indian dental academy

“EFFICIENCY OF NEWER
GENERATION PREADJUSTED
EDGEWISE APPLIANCES”
– A RANDOMIZED
CONTROLLED TRAIL

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INDIAN DENTAL ACADEMY
Leader in continuing dental education


• Andrews increased anterior tip due to “Wagon
wheel effect” where tip was lost as torque
was added(4:1).
• He added additional tip of 100 in the upper
anterior segment and 120 in the lower anterior
segment.
• Due to extra tip built into the anterior
brackets there was the tendency for anterior
teeth to incline forward during the initial
phase of leveling and aligning.


• Attempts were made to eliminate or
minimize this effect by connecting
anterior segments to posterior
segments, usually with elastic forces.
But this created a greater demand for
anchorage control during this initial
stage of treatment.
• Increased elastic force resulted in
“roller coaster effect”.

• The anterior tip specifications for the
original SWA and Roth were all greater
than the research findings. Additional
tip had been built in, over and above the
scientific means, for e.g., the important
upper canine carried 110 in the first
generation (SWA) and then 130 in the
second generation (Roth) system,
compared with the research finding of
80.

Additional anterior tip was a disadvantage
for three reasons:
• It created a significant drain on
Antero-posterior (A/P) anchorage.
• It increased the tendency to bite
deepening during the alignment stage.
• It brought the upper canine root apex
too close to the first premolar root in
some cases

Tip values
Reduced Upper and Lower Anterior Tip
Upper Anterior Tip
Centrals

Laterals Canine

Lower Anterior Tip
Centrals

Laterals

Canines

Andrew’s norms

3.59

8.04

8.4

0.53

0.38

2.5

Original SWA

5

9

11

2

2

5

Roth SWA

5

9

13

2

2

7

MBT Versatile

4

8

8

0

0

3


• Mclaughlin, Bennett and Trevisi
redesigned the entire bracket system
to complement their proven treatment
philosophy and to overcome the
perceived inadequacies of the original
SWA and Roth Prescription appliances.


• By using additional tip in the anterior
brackets, anywhere from 2 to 3 mm
of molar anchorage can be lost in
bringing the roots of the anterior
teeth to this over angulated position.


• Because tip appears to be the strength
of the pre adjusted appliance and
because with light forces there is no
need for second order compensation or
“anti-tip”, when designing the MBT
bracket system, it was decided to base
the anterior tip on the original research
values.

• The present double blind, randomized
controlled trial is being undertaken to
study the efficiency of a newer
generation preadjusted edgewise
appliances (MBT) compared to an earlier
generation preadjusted edgewise
appliances (Roth) in terms of anchorage
control and efficient alignment during
the initial stage of treatment.

METHODOLOGY
• Study group comprised of 20 patients who
need first premolar extraction as a part of
orthodontic treatment.
• The Head of Department who is not involved
in the study coded two bracket system (MBT
and Roth), each containing 10 sets to Group A
and Group B.
• The principal investigators did not know which
group belongs to which bracket system until
the results were analyzed.

• After the results were obtained and analyzed
then groups were recorded accordingly.
• Group A was found to be MBT bracket system
and Group B was Roth bracket system.
•

20 patients were randomly taken from the
Department OPD. They were randomized by
asking the patient to chose the token (Red
for Group A and Blue color for Group B).

Treatment Protocol :
• The cases under study were strapped up
with 0.022 MBT or 0.022 Roth full
banded prescriptions.
• Bracket positioning was done using
individualized bracket-positioning charts.
• Lace backs are used for antero-posterior
canine control
• Bend backs for antero-posterior incisor
control.

• All 2nd molars are banded and
transpalatal arch placed.
• As leveling and alignment progressed
round 0.016 HANT were replaced by
0.019” x 0.025” HANT which was later
replaced by 0.019” x 0.025”SS wire.


Incisor Torque (Lateral Cephalogram)
• Maxillary Incisors:
Angle formed between long axis of maxillary
incisor to the S-N plane was measured before
treatment and after alignment.
• Mandibular Incisors :
Angle formed between long axis of mandibular
incisor to the mandibular plane was measured
before treatment and after alignment.


Measurement of tip


Reference lines used to measure
tip


Reference line for
uppers

Tip Value (OPG)

Reference line
for lowers

MBT

ROTH

Upper right canine

0.8 ± 1.5

2.2 ± 1.2

Upper left canine

0.7 ± 1.4

2.6 ± 1.6

Upper right canine

0.4 ± 1.2

1.8 ± 2.0

Upper left canine

0.3 ± 2.7

1.0 ± 1.2

Not significant

Significant

Anchorage consideration (Lateral Cephalogram)
X-axis
70 to SN
Y-axis
900 to X-axis

Horizontal
measurements


GRAPH - II : Y AXIS TO UPPER INCISOR INCISAL TIP

76.1

76.5
76
75.5

75.5
75.2

75
74.4
74.5
74
73.5
Pre

Post

Group A Group B

GRAPH - III : Y AXIS TO UPPER MOLAR MESIO-BUCCAL CUSP

45.8
46

45.6

45.5
45
44.5

43.9

44
43.5
43
42.5
Pre

Post

Group A

Group B


45.6

HORIZONTAL MEASUREMENT CHANGES IN MBT PRESCIPTION
.
PATIENT

Anchorage
loss of
molars (0.2 ±
0.9)

Slight
proclination of
anteriors(.03 ±
0.05 )

Lingual tipping of
lower incisors1.5
± 0.2

HORIZONTAL MEASUREMENT CHANGES IN ROTH PRESCIPTION
.

PATIENT

Anchorage
loss of
molars (1.7
± 0.5 )

Proclination of
anteriors(1.7 ±
0.9)

MORE ANCHORAGE LOSS AND ANTERIOR FLARING IN MAXILLARY ARCH

• In the present study we had coordinated the arch forms in both the
groups so there was no significant
variation between both the groups
• In the present study the selected cases
were bearing bimaxillary protrusion with
no functional interference so the result
indicated none of them to have
functional occlusal changes.

• The flaring of maxillary anteriors in group B
(Roth prescription) was due to extra- tip
added to the anterior brackets. This extra tip
resulted in increase in the arch length leading
to the flaring of anteriors. Lace backs and
bend backs which were given to control this
anterior flaring resulted in increased mesial
force on molars ensuing anchorage loss in
group B patients.


TORQUE


• When the edgewise appliances is used, the application
of resilient wires in the leveling phase leads to
undetectable force systems and torques, possibly
resulting in unintended individual tooth movements
with undesirable side effects. During retraction or
protraction, a resilient wire may cause jiggling
movements; the elastic deformation of the wires may
trigger intrusive and extrusive side effects that may
induce undesirable histologic responses. These
problems must be taken into account when comparing
type of tooth movement and histologic findings.

•Source: AJO-DO on CD-ROM (Copyright © 1998 AJO-DO), Volume 1995
Apr (360 - 371): Histologic tissue response after tooth movement Wehrbein,
Fuhrmann,and Diedrich

• Usually upper molar torque need not be
changed.
• When resilient wire placed posterior
teeth first move buccally and then
palatally producing dehiscence,
fenestrations , severe root resorption
and sinus perforation. This is due torque
change from anteriors to posteriors


Thurow pointed out that unless all teeth in an arch
need torquing in the same direction and degree there
should be some play between the arch wire and
brackets. If there is not, as the wire is activated in
engaging a bracket on a tooth requiring torque,
adjacent teeth are torqued in the opposite direction
first and then complete unnecessary “round trip” as
the wire returns to its passive state. Any activation
for torque should be less than the degree of play in
the opposite direction at adjacent teeth.


• Torque values
Maxillary
Tooth
ROTH

II
molar
-9

I
Molar
-9

II
PM
-7

MBT

-14

-14

-7

I PM Canine Latera Central
l
-7
-7
8
12
-7


0

10

17

• With an .017” x .025” wire in .018” slot
slop is 4.50
• With an .019” x .025” wire in .022” slot
slop is 10.50
DR. THOMAS D. CREEKMORE (1979)


ROTH
Maxillary
II
I
Tooth
molar Mola
r
ROTH
-9
-9

II
PM

I PM Canine Latera Centra
l
l

-7

Difference in torque = 150

-7

-7

8

150

12

40

Slop= 4.50
11.50 of unnecessary back and forth
torque action.
When 17x25 placed in 18 slot brackets slop
between wire and slot is just 4.50. The torque
difference between lateral incisors and posteriors
is 150 so there is unnecessary back and forth
torque action.

• Because of reduce play between wire
and slot in Roth prescription appliance
more force is exerted by rectangular
niti. This lowers the pain threshold for
the patient resulting in increased
hyalinization. The treatment time during
leveling and aligning stage is increased
due to “jiggling” and round tripping of
teeth.

MBT
Maxillary
II
I
Tooth
molar Molar
MBT

-14

-14

II
PM
-7

I PM Canine Latera Centra
l
l
-7

70

0

70

Difference in torque =Maximum 100
Slop= 10.5

0

No unnecessary back and forth torque
action.

10

100

17

70

• Increased pain threshold
due to reduced force
•Reduced treatment time

Materials and method


• FE analysis solves a complex problem by
redefining it as the summation of the
solutions of a series of inter related
simpler problems.


• CT scan images of Maxilla were taken in
the axial direction, parallel to the occlusal
plane. Sequential CT images were taken
at 3-mm intervals to reproduce finer and
detailed aspects of the geometry.


CT SCAN (AXIAL VIEW PARALLEL TO OCCLUSAL PLANE)

TRACINGS OF CT SCAN

AUTOCAD TRACING OF EACH LAYER


SUPER IMPOSITION OF ALL LAYERS


• Along the centerline of bone, of each CT
image, geometric points were defined and
assigned X, Y, and Z coordinates, which
were fed into the preprocessor of the
software for grid generation. The FE
program used in this study was NISA-II
Display-III and was run on a Pentium-III
computer

• The grids created were then joined to form
lines. The geometric lines passing through
these points described the measured
bone geometry as close as possible.


• The next step was to generate geometric
surfaces by joining lines together. Each
layer created was stacked one above the
other in the axial direction and joined by
straight lines. Lines were joined to create
patches. Only 7 layers of the maxilla with
respect to the dentition was modeled and
analyzed.


• The next step was to convert the geometric
model into a FEM. The geometric entities
created in the previous step were replaced with
finite elements and nodes at this stage.
• The complete geometry is now defined as an
assemblage of discrete pieces called elements
and are connected together at a finite number
of points called nodes.
• In this study a linear four nodal quadrilateral
and triangular shell elements were used, which
were able to take membranes into account, ie,
in-plane deformation as well as bending
deformations.

• The shell elements have six degrees of freedom
(DOF) at each of their unstrained nodes: three
translations (X, Y, and Z) and three rotations
(around the X, Y, and Z axes).
• In the present study the model consisted of
44142 DOF, which gives a more consistent
result as compared with previously published
studies. The total number of elements and
nodes created was 9218 and 8980, respectively

Centrals

laterals

st
Canine 1st Premolar 2nd Premolar 1 molar

CAD MODEL

3D-FE CAD MESH SHOWING MAXILLARY TEETH WITH
PERIODONTAL SUPPORT

TOOTH

PDL

BONE

3D-CAD MODEL OF MAXILLARY DENTITION AND
PERIODONTAL SUPPORT

3D-FEM analysis done on 0.017 x0.025 niti in 0.018 slot and 0.019 x0.025
niti in 0.022 slot to find torquing force applied by the wire

• Force levels
Maxillary
Tooth
ROTH

I
Molar
-.193

II
PM
-.302

I PM

Canine

-.516N

-1.547N

.6N

1.57N

MBT

-.09N

-.16N

-.2N

-.52N

.2N

.52N


Lateral Central

STRESS DISTRIBUTION IN
ROTH
(0.017” x 0.025” in 0.018 slot)


STRESS DISTRIBUTION IN
MBT
(0.019” x 0.025” in 0.022 slot)


DISPLACEMENT IN
ROTH
(0.017” x 0.025” in 0.018 slot)


DISPLACEMENT IN
MBT
(0.019” x 0.025” in 0.022 slot)


ROTH

MBT

INCISOR
DISPLACEMENT

28.49 X 10-4 Mpa

10.25 x 10-4Mpa

MAX STRESS

.9253Mpa

.3770 Mpa


PARAMETER

TIME TAKEN
LEVELING AND
ALIGNING

GROUP

TREATMENT
TIME

FOR GROUP A 3.5MON ±0.5

GROUP B 4.1MON ±1.1


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Efficiency of newer generation edge wise applience /certified fixed orthodontic courses by Indian dental academy

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