Download Soldered Power Arm: An Easy and Effective Method for Intrusion

Ketan K Vakil et al
10.5005/jp-journals-10021-1221
Clinical innovation
Soldered Power Arm: An Easy and Effective Method for
Intrusion and Retraction of Anterior Teeth
1
Ketan K Vakil, 2Pawankumar Dnyandeo Tekale, 3Jeegar K Vakil
ABSTRACT
The orthodontic correction of deep overbite can be achieved
with several mechanisms that will result in true intrusion of
anterior teeth, extrusion of posterior teeth, or a combination of
both. For the orthodontic correction of bimaxillary dentoalveolar
protrusion with deep bite, there are several treatment modalities
like segmented arch approach, retraction and intrusion utility
arches, temporary anchorage devices. Though not a novel
therapeutic concept, the use of miniscrew implants to obtain
absolute anchorage has recently become very popular in clinical
orthodontic approaches. To allow the use of sliding mechanics
for bodily retraction with intrusion of anterior teeth, we devised a
soldered power arm (SPA) on standard molar tube. It is simple,
stable, precise and effective in cases where anterior teeth need
to be simultaneously retracted and intruded. A power arm can
be readily fabricated from 20 gauge stainless steel wire and
soldered on the molar buccal tube so as to avoid any distortion
or loosening of power arm from molar tube during the course
of the treatment. The SPA works efficiently with the molar being
stabilized in all three planes of space. The resultant force vector
is directed more apically toward the center of resistance of the
anchor unit, which resulted in the treatment outcome of retraction
and intrusion of the anterior teeth and correction of the deep bite.
Keywords: Soldered power arm, Retraction, Intrusion, Adult
treatment.
How to cite this article: Vakil KK, Tekale PD, Vakil JK. Soldered
Power Arm: An Easy and Effective Method for Intrusion and
Retraction of Anterior Teeth. J Ind Orthod Soc 2014;48(1):72-75.
Source of support: Nil
Conflict of interest: None
(10-15 gm/tooth) is applied during intrusion to minimize root
resorption and decrease side effects on the reactive unit. It
has been documented that the use of heavier forces will not
increase the rate of intrusion.3-5
For the orthodontic correction of bimaxillary dento­
alveolar protrusion with deep bite, there are several treatment
modalities like segmented arch approach, retraction and
intrusion utility arches, temporary anchorage devices. The
segmented arch technique requires precise wire bending
controlled tooth movement with anchorage control. But
these are unesthetic and require good patient compliance.
Though not a novel therapeutic concept, the use of miniscrew
implants to obtain absolute anchorage has recently become
very popular in clinical orthodontic approaches.6,7
To maintain the arch perimeter while using sliding
mechanics, 0.017" × 0.025" stainless steel wire (for 0.018"
appliances) or 0.019" × 0.025" stainless steel wire (for 0.022"
appliances) without any 2nd-order bends. An auxiliary
attachment can then be bonded to the cervical portions of
the involved teeth, allowing the applied force to pass through
the center of resistance.8
To allow the use of sliding mechanics for bodily retrac­
tion with intrusion of anterior teeth, we devised a soldered
power arm (SPA) on standard molar tube.
Received on: 29/6/13
Appliance Construction
Accepted after Revision: 16/7/13
1. The length of the power arm is determined according to
the resultant force vector that is needed for simultaneous
retraction and intrusion of teeth and also according to
the sulcus depth in buccal vestibule in molar region.
2. Bend the desired section of the 20 gauge stainless steel
wire with rounded hook for attachment of the nickel
titanium closed-coil springs or elastic chain (Fig. 1).
3. Care should be taken for any mucosal irritation with the
cut end of the wire.
4. Place the distal end of the power arm on the molar tube
(Fig. 2) and stabilize it.
5. Before starting soldering the power arm to molar tube,
auxiliary tube and archwire slot should be blocked with
0.017" × 0.025" stainless steel wire (for 0.018" appliances) or 0.019" × 0.025" stainless steel wire (for 0.022"
appliances), so that the solder material will be restricted
from flowing at these sites (Fig. 2).
Introduction
Various treatment techniques and biomechanical approaches
have been suggested over the past decades for the correction
of bimaxillary dentoalveolar protrusion with deep bite to
achieve en masse retraction and intrusion of anterior teeth
with minimal or no anchorage loss.1,2 During intrusion of
anterior teeth, optimal magnitudes of force may be delivered
constantly using low load deflection springs. Low force
1
Professor and Head, 2Resident, 3Senior Lecturer
1-3
Department of Orthodontics, SMBT Dental College and
Hospital, Ahmednagar, Maharashtra, India
Corresponding Author: Ketan K Vakil, Professor and Head
Department of Orthodontics, SMBT Dental College and Hospital
Ahmednagar, Maharashtra, India, e-mail: [email protected]
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Soldered Power Arm: An Easy and Effective Method for Intrusion and Retraction of Anterior Teeth
Fig. 1: Bending the desired section of the 20 gauge stainless
steel wire
Fig. 2: Stabilization of power arm on molar tube
Fig. 3: Pretreatment extraoral and intraoral photographs
6.Apply flux and solder material and start with soldering,
once soldered, finishing of the power arm is done.
7. Adjust the hooked vertical end of the SPA so that the
assembly clears the alveolar mucosa.
8. Cement the molar bands and SPA assembly with glass
ionomer cement.
9. Nickel titanium closed-coil springs, each exerting a
retraction force of 250 to 300 gm, are engaged between
the SPA and soldered anterior hooks on the archwires, the
forces exerted by the springs were directed more apically,
toward the center of resistance of the anchor units. The
SPAs also exerted distal forces against the molars.
Appliance Placement
Prior to appliance placement, patient selection is done and
patient is evaluated for overjet and overbite (Fig. 3). Once
the upper and lower arches have completed alignment and
leveling, maxillary and mandibular anterior teeth from
canine to canine are consolidated and single unit is formed
with continuous steel ligation. Full slot engagement of
stainless steel wire is done either in 0.018 or 0.022" slot.
Transpalatal arch should be given for stabilization of upper
arch in transverse plane.
Power arms are soldered to the molar tubes and
molar bands cemented. To prevent deepening of the
bite during retraction 0.017" × 0.025" SS wire placed in
0.018" slot whereas in 0.022" slot 0.019" × 0.025" SS
wire is used. Anta hooks are soldered on the wire. Nickel
titanium closed-coil springs (12 mm), each exerting a
retraction force of 250 to 300 gm, is engaged between
the SPA and soldered anterior hook on the archwires
(Fig. 4). Forces, as vectors, can be combined or divided
The Journal of Indian Orthodontic Society, January-March 2014;48(1):72-75
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Ketan K Vakil et al
Fig. 4: Mid-treatment intraoral photographs
mathematically. Two or more forces acting at a single point
can be added using simple trigonometry or vector addition
and represented as a single force at that point.9 So, resultant
force required is the resultant vector which is more than the
horizontal vector (Fig. 5).
Force level for simultaneous retraction and intrusion is to
be maintained throughout the treatment. As the force vector
is directed more apically, toward the center of resistance
of the anchor units, there is simultaneous retraction and
intrusion of the anterior teeth with correction of the deep
bite (Fig. 6).
Discussion
It is simple, stable, precise and effective in cases where
anterior teeth need to be simultaneously retracted and
intruded. A power arm can be readily fabricated from 20
gauge stainless steel wire and soldered on the molar buccal
tube so as to avoid any distortion or loosening of power
Fig. 5: Diagram showing resultant force vector
arm from molar tube during the course of the treatment.
The SPA works efficiently with the molar being stabilized
in all three planes of space. The resultant force vector is
directed more apically toward the center of resistance of
the anchor unit, which resulted in the treatment outcome of
retraction and intrusion of the anterior teeth and correction
of the accentuated overjet and deep bite. SPA eliminates
Fig. 6: Extraoral and intraoral photographs after debonding
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Soldered Power Arm: An Easy and Effective Method for Intrusion and Retraction of Anterior Teeth
the use precise and unesthetic segmented wire bending and
use of miniscrew anchorage for the correction of bimaxillary dentoalveolar protrusion with deep bite.
Advantages of this Technique
•
•
•
•
Soldering the power arm makes the unit stronger and
more stable, avoiding any loosening of the appliance
during the course of the treatment
The need for apical miniscrews near the center of
resistance of the posterior teeth is eliminated, thus
reducing the treatment cost.
The hooked vertical end of the SPA can be adjusted in
the buccopalatal direction away from the gingiva in
molar region and the buccal mucosa, so that curvature
of the archwire will not result in soft tissue impingement
by the retraction spring or elastics.
As the posterior teeth are stabilized, there is less chance
of rotation of the occlusal plane.
References
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3. Shroff B, Leiss JB, Lindaur SJ, Burstone CJ. Segmented approach
to simultaneous intrusion and space closure: Biomechanics of
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1995;107:136-143.
4. Dellinger EL. A histologic and cephalometric investigation of
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