Efficiency of newer generation preadjusted edgewise appliances

““EFFICIENCY OF NEWEREFFICIENCY OF NEWER
GENERATION PREADJUSTEDGENERATION PREADJUSTED
EDGEWISE APPLIANCES”EDGEWISE APPLIANCES”
– A RANDOMIZED– A RANDOMIZED
CONTROLLED TRAILCONTROLLED TRAIL
www.indiandentalacademy.com

• 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

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

• 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

Tip Value (OPG)
Reference line
for lowers
Reference line for
uppers

Pretreatment tracing (ROTH)

Post treatment tracing (OPG)
There is significant decrease in angle between long axis of canines
and reference line (more than MBT)www.indiandentalacademy.com

Pre treatment tracing (MBT)

Post treatment tracing (MBT)
No significant change in angulations between pre and post tracings

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

75.2
74.4
75.5
76.1
73.5
74
74.5
75
75.5
76
76.5
Pre Post
GRAPH - II : Y AXIS TO UPPER INCISOR INCISAL TIP
Group A Group B

45.6
43.9
45.8
45.6
42.5
43
43.5
44
44.5
45
45.5
46
Pre Post
GRAPH - III : Y AXIS TO UPPER MOLAR MESIO-BUCCAL CUSP
Group A Group B

Slight
proclination of
anteriors(.03 ±
0.05 )
Anchorage
loss of
molars (0.2 ±
0.9)
Lingual tipping of
lower incisors1.5
± 0.2
HORIZONTAL MEASUREMENT CHANGES IN MBT PRESCIPTION
. PATIENT

Proclination of
anteriors(1.7 ±
0.9)
Anchorage
loss of
molars (1.7
± 0.5 )
HORIZONTAL MEASUREMENT CHANGES IN ROTH PRESCIPTION
. PATIENT
MORE ANCHORAGE LOSS AND ANTERIOR FLARING IN MAXILLARY ARCH

• In the present study we had co-
ordinated 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.

CT SCAN (AXIAL VIEW PARALLEL TO OCCLUSAL PLANE)

TRACINGS OF CT SCAN

AUTOCAD TRACING OF EACH LAYER

SUPER IMPOSITION OF ALL LAYERS

CAD MODEL
Centrals 1st
PremolarCaninelaterals 2nd
Premolar 1st
molar

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

TOOTH
PDL
BONE
3D-FE MODEL OF MAXILLARY DENTITION AND PERIODONTAL
SUPPORT

STRESS DISTRIBUTION IN ROTH
3.115MPA
3.115MPA
15.569MPA

STRESS DISTRIBUTION IN MBT

MBT ROTH
ANTERIOR LABIAL
CORTICAL BONE
9.67 Mpa 15.91Mpa
LINGUAL ASPECT OF
INCISOR ROOTS
7.45 Mpa 12.84Mpa
CERVICAL 1/3RD
INTERPROXIMAL
BONE BETWEEN 2ND
PREMOLAR AND 1ST
MOLAR
10.34 Mpa 16.76 Mpa
DISTAL ASPECT OF
APICAL ROOTS OF 1ST
MOLAR
9.54 Mpa 15.70 Mpa

DISPLACEMENT DISTRIBUTION IN ROTH

DISPLACEMENT DISTRIBUTION IN
MBT

MBT ROTH
INCISOR
DISPLACEMENT
9.44 X 10-4
Mpa 14.67x 10-4
Mpa
MOLAR
DISPLACEMENT
9.00 X 10-4
Mpa 13.84 x10-4
Mpa

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
II
molar
I
Molar
II
PM
I PM Canine Latera
l
Central
ROTH -9 -9 -7 -7 -7 8 12
MBT -14 -14 -7 -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
Tooth
II
molar
I
Mola
r
II
PM
I PM Canine Latera
l
Centra
l
ROTH -9 -9 -7 -7 -7 8 12
40150
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.
Difference in torque = 150
Slop= 4.50
11.50
of 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
Tooth
II
molar
I
Molar
II
PM
I PM Canine Latera
l
Centra
l
MBT -14 -14 -7 -7 0 10 17
100
7070
70
Difference in torque =Maximum 100
Slop= 10.50
No unnecessary back and forth torque
action.
• Increased pain threshold
due to reduced force
•Reduced treatment time

STRESS DISTRIBUTION IN ROTH

PARAMETER GROUP TREATMENT
TIME
TIME TAKEN FOR
LEVELING AND
ALIGNING
GROUP A 3.5MON ±0.5
GROUP B 4.1MON ±1.1

Efficiency of newer generation preadjusted edgewise appliances

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