Torque and its_application /certified fixed orthodontic courses by Indian dental academy

TORQUE
AND ITS APPLICATION TO
ORTHODONTICS
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


Torque is probably one of the most important and
potent forces of orthodontic treatment mechanism with
proper understanding and with systemic technical
approach torque is not difficult to accomplish
The operator’s ability to control torque properly will
mean the difference between artistically treated case that
has all esthetic beauty desired in a finished denture and an
ordinary tooth straightening accomplishment that contains
very few of these desirable features


DEFINITION
Torque being more related to
engineering terms is defined as “The force system
transmitted by and through a structural or
machine member, capable of producing pure
rotational displacement about the longitudinal
axis”.


In Orthodontics, as stated by Dr. EARMAN D. RAUCH
“Torque is the force that enable the
orthodontist to control the axial inclination of the teeth
and to place them in the harmonizing positions that are
so desirable for a nicely finished results. Torque is the
force that gives the operator control over the movement
of the roots of the teeth”.
Torque is a force that assists him to bring about a
desirable change of point A & B which in turn helps to
bring about desirable facial changes in his patients.


WHY? WHEN? & HOW?
Why ?
• To bring about labiolingual movement
of the teeth
• To retain the teeth in the cortical bone
• To avoid relapse
• To give a natural finish to the dentition


When?
• When there is uncontrolled tipping of the crown
• When the clinical situation demands cortical activation
• In third order bends of finishing and artistic positioning in
a pre adjusted edgewise system.
• In pre surgical and post surgical phases for the precise
placement for axial inclination of teeth
• As a device to augment anchorage demands of that
particular situation.


How ?
• Torque can be done both in fixed and removable
machanotherapies
• Torque in fixed appliance can be employed in different
ways
1. By giving a twist in an arch wire
– commonly used in edgewise techniques
2. Torque exerted by the bracket itself
– Pre adjusted edgewise appliance
3. By use of torquing auxiliary
- widely used in Beggs technique and edgewise
technique
• These will be dealt in detail in my seminar

ARMAMENTARIUM


BIO ENGINEERING PRINCIPLES OF TORQUE
MECHANISM IN ORTHODONTICS
•

In a Rectangular wire, torque is incorporated by using a permanent
twist in the arch wire, where as in a Round wire torquing auxiliaries
are used to deliver third order couples to the anterior teeth.

•

The amount of torsional activation achieved upon complete appliance
engagement is however actually less than this permanent twist angle.
The principal portion of difference is the third order clearance between
the arch wire and the bracket slot. This clearance may be computed
from the actual cross section of the arch wire and occlusogingival
bracket slot width. The third order clearance depends upon the actual
wire in the slot dimensions and in effect, upon stiffness of the bracket
slot

•

In response to the third order activation, the slot will open slightly as
the wire attempts to deactivate.

THIRD ORDER CLEARANCE BETWEEN
RECTANGULAR WIRE AND EDGEWISE BRACKET


THIRD ORDER CLEARANCE BETWEEN
RECTANGULAR ARCH WIRE AND BRACKET SLOTS


• Pre Torque Brackets are sized, in part according to
the third order angulation of their slots with
respect faciolingual reference
• Torque is determined in gram-millimeters or
ounce inches
• To quantify torque correctly the combination shaft
stiffness and twist activation are necessary.


COMPARISON OF STRUCTURAL PROPERTIES IN TORSION OF
RECTANGULAR ARCH WIRES INFLUENCED SOLELY BY
CROSS-SECTIONAL DIMENSIONS


The chart represents the relative theoretical values
of elastic stiffness, range and strength in torsion per
unit length of common material for four rectangular
wires
The torsional stiffness of the largest wire is seen
to be five times that as the smallest wire in the table.
The size of the wire and range is inversely
proportional. The other structural parameters are the
wire material, longitudinal dimension and physical
character of the wire.


To compare third order couple generated by the
rectangular arch wire and the torquing span, the
difference and the direction of the pairs of forces and
the moment arms should be noted.
The force exerted by the rectangular arch wire are
directed nearly occlusogingivally whereas the force
pair from the torquing spur acts labiolingually. The
difference in the direction meaningless with respects
to the action delivered to the dentition

Sagittal views of Maxillary incisors load at byrectangular wire torque (left) and spur torque and
different force direction and inherent moment arms


The inheritant moment arms of the rectangular
wire and the spur, couples are the labiolingual wire
cross section and occlusogingival height of the spur
respectively.
They differ approximately in one order of
magnitude i.e. the factor of ten. Hence if the size of
each force generator by the spur is about 1/10 that off
each force of the pair generated within the bracket. So
the results approximately equal third order couples
applied by two appliances.

The Begg torquing auxiliary is usually formed in
0.012, 0.014 or 0.016 stainless steel wire. The
purpose of the base arch wire is to counter the
extrusive potential associated with activation of
auxiliary.


A NOTE ON FABRICATION OF THE SQUARE
OR RECTANGULAR WIRE AND THE METHOD
THEY DELIVER TORQUE ON THE TOOTH
Square or rectangular arch wires are fabricated from
round wires by a process of rolling rather than drawing.
The round wire is passed through a device called a Turks
head which is a set of two rollers positioned 900 to each
other and rolled to the desired dimensions. The edges of
the wire remain rounded after rolling process, resulting in
edge bevel. The edge bevel is expected to be a critical
factor for actual torque expressed by a specific square or a
rectangular arch wire and bracket combination. Since the
edges of the arch wire is first engaged the bracket for
torque delivery.

Largest edge bevels are observed on beta titanium
segments due to the mechanical and wire properties of this
alloy. The amount of edge bevel on the wire will influence
the amount of torque exhibited by the wire bracket
combination for a rectangular wire in a rectangular molar
tube, the critical value of the wire dimension is the
diagonal or hypotenuse of the wire cross section as shown
in the figure


It is this dimension that contacts the wall of the
lumen and engages the wire against further rotation.
This with the variation in the tube dimension causes
deviation in torque clinically. This deviation in torque
may differ significantly enough to require diverse
torque on left and right molars in the same arch.


METHODS OF TORQUING IN VARIOUS
APPLIANCE MECHANICS
BEGGS MECHANOTHERAPY :
The torquing in BEGG is testimonial to the genius Dr.BEGG,
both with regards to its concept and the designs. The special feature
of BEGG appliance in separating the tooth moving forces from the
arch wire forces gives at a unique advantage. Various torquing
auxiliaries developed Dr.BEGG the
1.
Spur design having 2,4 and 6 pairs
2.
Mouse-strap for lingual root torque
3.
Udder arch for labial root torque
4.
Reciprocal lateral torquing auxiliary
5.
Reverse torquing auxiliary
6.
KITCHTON torquing auxiliary
Single root torquing auxiliary developed Dr.Kesling

RECENT ADVANCES • 1.
• 2.

• 3.
• 4.
• 5.

Refined BEGG

Reciprocal torquing auxiliary (‘SPEC’) Design
Reverse torquing auxiliary for controlling the roots
of the canine of the premolar by Franciskus Tan in
November 1987.
Buccal root torque and upper molars
Labial root torque only in the lateral incisors
MAA Auxiliary by Mollenhauer


TORQUING AUXILIARY WITH SPURS
Action of the torquing auxiliary
1.

The auxiliary bent into a small circle, when fixed
in the mouth, is spread out along the wider anterior
curvature of the arch wire. The lingual torquing effect
is an account of two factors.
a. Firstly, the vertical plane in which the torquing
auxiliary orients when fitted on two central incisors, is
changed to a horizontal plane of arch wire when fully
tied to it.

Secondly, when the torquing auxiliary is
opened to a larger arc of anterior portion of the
arch wire it rolls inwards.


Both the effects, force the tips of the spurs to
press in a lingual direction against the gingival portion
of the crown. Reciprocally the inter spur spans of the
auxiliary tend to lift away in the labial direction.
THUS A FORCE COUPLE IS CREATED. The
labial forces are resisted by the bracket slots and the
base arch wire to which the auxiliary is tied. Thus
accentuating the action of lingual root moving forces


ABOUT “THE SPUR”
1. The Auxiliary should be constructed in 0.012
premium plus wire (preferable pulse straightened)
unlike in 0.014 or 0.016 special plus wire which were
previously used.
2. The length of the spur does affect the force
produced. A short spur will produce much greater
force that will drop rapidly when the teeth start getting
torqued, as against a longer spur that produces a
gentler and more constant force.

The length of the spur should be kept at about
5 mm; but it should be varied depending on the
clinical crown height, leaving it about 1 mm short
of the gum to facilitate proper hygiene


3. Inclination of the spurs to the horizontal

(occlusal) plane is kept 00. In other words, the
activation is 100%.
4. The distal leg of every spur is kept
slightly shorter by about 0.5 mm, so that the distal leg
does not project incisally to the main arch wire on
tying


5. Activation of the spur
a. The inter-spur span is curved as recommended by
Dr.Kesling’


b. Kept straight as shown in Swain’s chapter


c. Angulated midway as in BEGG


d. As recommended by Dr.Jayade – normally size of
the old 50 paise coin

The force generated by the auxiliary increase with
decrease in the diameter in the circle and vice-versa

Two of the modification commonly required in the
spur design torquing auxiliary are as follows.
a. Reverse labial torque on one or both the
lateral incisors : Boxes at right angle to the plane of the
spurs are made to lie at the incisal area of the lateral
incisor(s). Crossover bends are made on either side of the
lateral incisor bracket to permit the auxiliary to pass over
the base wire, similar to the bends described in the section
on the MAA
Torquing boxes on the canines for lingual root
torque : Instead of making spurs for the canines, boxes
can be provided. The ends of this auxiliary need not
extend beyond the canine area


MOLLENHAUER’S ALIGNING AUXILIARY
(MAA) AND ITS MODIFICATIONS
MAA
auxiliary
was
developed
by
Dr.
MOLLENHAUER and it was given the name as “An
Aligning Auxiliary for Ribbon Arch Brackets”. The
MAA, attempts root control from the very beginning, of
the treatment without significantly affecting the anchorage
and overbite correction. This has become possible by
using a combination of a stiff base arch wire made from
0.018” Premium plus, and ultra light root moving forces
from the MAA made from the 0.009” Supreme grade wire


Requirements for use of the MAA
Mollenhauer has enumerated the requirements as
1. It must generate very light root moving forces.
Therefore, the wire size must not exceed 0.009”.
2. For the same reason, when reciprocal torque is required
on adjacent teeth, the adjacent rectangles must not diverge by
more than 45 degrees.
3. At the same time, the auxiliary must be able to resist
deformation. Hence, it must be made in a highly resilient wire
viz. Supreme grade (preferable pulse straightened)


4. The base wire should be able to resist the vertical and
transverse reactive forces from the MAA. Therefore,
it must be made in 0.018” Premium Plus wire.
5. In Mollenhauer’s application, the MAA is always
engaged first and the main wire is engaged piggyback.
The rectangles for lingual root torque lift away from
the tooth surface, which are held down with the help
of pins, thus indirectly transmitting the torquing action
through the pins to the brackets onto the teeth.


Therefore, he recommends the thickest possible lock or
hook pins (such as the pins for Ceramaflex brackets)


Advantages of the MAA
• According to Molenhauer, the advantages of
MAA are :
1. Efficacy in intrusion and advantages retraction of the
anterior teeth,
2. Efficiency in rapid bodily alignment of the anterior teeth
using gentle forces
3. Stable results.
4. Reciprocability of torquing forces on the in standing
laterals or palatally placed canines.

5.

Periodontal advantages in such cases, because the
gingival dehiscence associated with prolonged labial
root torquing of such teeth during the 3rd stage is
eliminated.

6.

A short stage III, because the early root control
minimizes (uncontrolled) root tipping in the opposite
direction

7.

Possibility of growing cortical bone at the A and B
points


VARIOUS APPLICATIONS OF THE MAA
1. Originally, the MAA was introduced for bodily
alignment of crowded teeth. The looped arch wire like effect
(expansion + de rotation + vertical leveling) was combined
with lingual and / or labial root torque


VARIOUS APPLICATIONS OF THE MAA
2.

By bending more positive torque into the MAA, it
can be used after the stage I as a braking mechanism.
Mollenhauer strongly recommends applying labial
root torque on the lower incisors in growing
brachyfacial cases, to prevent their roots from
lingualizing (which can happen due to intrusive forces
and due to contraction of trans-septal fibers in
extraction cases). This helps in a better profile
control. The MAA can be used for labial root torque
on the upper incisors in Class III cases

3.

In later writings, Mollenhauer described use of the
same auxiliary for controlling the mesio-distal root
positions from the beginning.
He called this
application ‘MAA-tip. A ligature wire tied to the
auxiliary and to the pin transfers the tipping effect to
the tooth.


4.

Modification can be used for reciprocal root torque


Other boxed Auxiliaries
Mini versions of MAA ranging from 0.009” to
0.012” and curvatures facing incisally facing incisally
or gingivally, for labial or lingual root control
respectively. They are employed on two or more
number of anterior teeth in either or both the arches.
The force exerted by the boxes is varied, as per the
individual requirement, by varying the diameter of the
wire from which the auxiliary is made, size of the
boxes and acuteness of the curvature.

Obviously, the auxiliaries generating lighter
forces are employed in the first and second stages of
treatment, while those generating higher forces are
meant for the third stage and sometimes in the second
stage as a breaking mechanics
a. Two boxes on the upper central incisors for lingual
root torque after the teeth are aligned


b. Two boxes on the in standing upper or lower lateral
incisors for labial root torque.


‘Jenner’ auxiliary two boxes on the upper or
lower canines with very prominent roots. That is
made up of 0.012” wire. Lingual root torque exerted
by the boxes reduces the prominence to facilitate
anterior retraction


d. ‘SPEC’ design – Reciprocal torquing
auxiliary – it is employed when two adjacent teeth
require root torque in opposite directions. One such
example is an in standing lateral incisor needing labial
root torque and the adjacent canine needing lingual
root torque. This auxiliary is made of lighter 0.009 or
0.010 could be used for controlling the root
movements during the first and second stages.
If needed in stage three it should be made of
0.012.The box on the tooth requiring labial root torque
is placed incisal to main wire, while the box on the
other tooth requiring lingual root torque sits
piggyback on the main wire .hence a crossover bend is
required between the two adjacent teeth because the
auxiliary has to cross over the main wire.varying the
angulation between the planes of two boxes can
control the force generated by the auxiliary

Some other torquing auxiliary designs
a. Single root torquing auxiliary proposed by
Dr.Kesling’. This is a very useful design for any tooth
(excepting the molars) requiring torque in the labial or
the lingual direction. It is particularly indicated on an
UPPER PREMOLAR , which needs buccal root
torque. To eliminate the cuspal interference from its
hanging palatal cusp. It is convenient to place the
long arm of the auxiliary piggy back over the main
arch wire. Since the main arch wire may not be untied
it could also lie occlusal to the base arch wire in the
slot as well. The long arm should extend to three to
four adjacent teeth when engaged in the brackets.

The long arm always faces mesially for the
premolar teeth. Depending on how the curvature is
pointing before the auxiliary is tied, the torque generated
will have lingual (palatal) or buccal root moving effect.
For example, the auxiliary fitted with its convexity
facing upwards will have a buccal root torquing effect
on the upper premolars, but the effect will be for lingual
root torque on the lowers, and vice-versa. The effect is
transmitted by the vertical extension of the auxiliary
through the bracket pillar onto the tooth; The long arm
could face either mesially or distally on the anterior
teeth, and action will depend on how the curvature of the
long arm relates to the base arch wire. This auxiliary is
made up of 0.012 size Premium Plus wire. The force
generated by it can be varied by changing acuity of the
curvature. More acute greater is the force generated.

b. Reverse torquing auxiliary for controlling the roots of
canines or premolars proposed by Dr.Franciskus Tan
- It was described for the labial root movement of a
palatally impacted maxillary canine, whose crown has
been aligned but the root is still placed palatally and
needs labial root torque. If required for lingual root
torque in other situations it is simply inverted well on
the premolars made up of 0.012” P+ wire conjunction
with a 0.018” or 0.020” inserted in the molar tube
from the distal end. An offset is placed in the
auxiliary to bypass the main wire rotated by 1800 for
activating it

c. Buccal root torque on the molars – When the
upper molar crowns roll buccally because of a lack of
control during the third stage, their roots must be
torqued buccally to lift their palatal hanging cusps. It
is made in 0.014” size and is fitted in the round molar
tubes alongside the main arch wire. It has ‘boot’
design occlusal extensions on the molars, and it is
inserted from the mesial end of the molar tubes.
The boot portion is twisted lingually and given a toe
in, and the whole auxiliary is suitable contracted. The
auxiliary need not be engaged in other brackets.
It can be ligated to the main wire at 2-3 places on
either side


d. Labial root torque only on the lateral incisors –
This is made up of 0.012” size wire, and is placed
with the convexity of the auxiliary facing gingivally.
The auxiliary is engaged first in the incisor brackets,
and the main wire is then engaged piggyback. The
boxes extend labially on the incisal area of the
crowns. This design is often required on the lower
incisors in those cases where the central incisors and
the canines are placed normally, and hence do not
require reciprocal lingual root torque


e. UDDER ARCH - The udder arch is made up of 0.16
S.S.wire. The vertical loops of the auxiliary can be
opened or closed as needed to assume accurate fit.
The distal ends of the auxiliary is tied to the lower
cuspid bracket. The vertical loops are slipped behind
the main arch wire and the auxiliary is tided to one or
two brackets to prevent dislodgement. It is very easy
to insert and remove. This is used for the reverse
torquing of the mandibular incisors.


f. Kitchton torquing auxiliary - It is used for applying
torque force on the anterior teeth. Kitchton auxiliary can
be used with Begg, edgewise and removable appliances. It
is made up of 0.016 Australian wire. Coils in the midline
assume gentle, and continuous torque force and also
provide means of attachment to the main arch wire.
It is of two types :
1) Small
2) Large


* Small auxiliary delivers gentle lingual root torque to
the central incisors only. It can be used with the
Hawley’s retainer for additional root torque.
Large auxiliary can deliver greater force to the
central incisor and can be adjusted to deliver torquing
force to the central and lateral incisors. It an also be
used with Hawley retainer for additional root torque


Mouse trap
Mouse trap design is very efficient but involves more
time patience and skill


EDGEWISE MACHANOTHERAPY
The edgewise arch appliance is the last of many
contributions of Dr.EDWARD H. ANGLE and was
introduced to the profession by one of his last
students, Dr.ALLAN G. BROADIE in 1929. It is an
exacting
appliance
requiring
the
thorough
understanding and skill manipulation. This technique
offers excellent controls in the labiolingual,
mesiodistal and vertical dimension


The classification of tooth movement associated
with edgewise appliance seem to be based upon the
type of movements rather than direction.
i. Movement of the First order
ii. Movement of the Second order
iii. Movement of the third order
We will see here movement of the Third Order
Before we go into it we will have quick view over
glossary


• Passive torque – torque for proper placement of the
wire
• Active torque – for active tooth movement
• Progressive torque- increase of the torque value
progressively as we go posteriorly in the dentition
• Torque force is named according to the action upon
the tooth crown.
1.
Lingual torque – crowns are tipped lingually
and roots labially / buccally
2.
Labial or buccal torque – crowns are tipped
labially or buccally and the roots lingually

THIRD ORDER MOVEMENTS :
It is defined as the difference in inclination of the
facial plane of crown at its mid point in an ideal
occlusion.
The third order bends better known as torque are
placed in the arch wire to effect buccolingual or
labiolingual root and crown movements in a single
tooth or a group of teeth


TECHNIQUE FOR GIVING A THIRD
ORDER BEND FOR VARIOUS THIRD
ORDER MOVEMENTS


Mass anterior lingual root
torque technique


Individual lingual Root torque
central incisor area


Checking the
amount of torque


Continuous posterior
torque


Progressive Posterior Root Torque


PRE ADJUSTED EDGEWISE
APPLIANCE:
Until the mind 1970’s most fixed appliance
therapy was carried out using the standard Edgewise
bracket, either in a single or twin from having a 900
bracket base and brackets slot angulation.
The Major disadvantage resulted from this
treatment are;
1. Arch wire bending is time consuming and tedious.
• The short comings of the bracket system and the
extreme skill required of the orthodontists resulted in
many under treated cases and the results are appeared
artificial

Molars were not in true CL-I relationship. Upper
incisor are under torqued . So the resulting occlusion had
the appearance of a ‘nice orthodontic result’ rather that a
pleasing natural dentition. And also the long term stability
of tooth adjustment was compromised by failing to
establish ideal tooth relationships.
Against this background Dr.Lawrence F.Andrews
developed the straight wire appliance which became
widely available in the mid 1970’s. It was hailed by the
clinician’s as a radical step forward offering the dual
advantages of less wire bending, coupled with an improved
quality of the finished cases

TORQUE IN THE BASE
Vs.
TORQUE IN THE FACE
Torque-in-base was an important issue with the first
and second generation pre adjusted brackets, because level
slot line-up was not possible with brackets designed with
torque-in-face. Torque in the base is said by Andrews to be
a prerequisite for a fully programmed appliance – that is,
one that produces acceptable results without arch wire
bends, assuming the brackets are placed correctly.
Albert H.Owen in 1980 conducted a study comparing
Roth Prescription and the Vari Simplex Discipline
appliance of Alexander concluded that while torque in the
base had a sound theoretical basis, its effectiveness is
greatly influenced by the clinician’s success in accurately
placing the brackets

The torque in the base means that the bracket
stem is parallel and coincides with the long axis of the
bracket slot. But, with the brackets having torque in the
face the slot is cut at an angle to the bracket stem,
therefore their long axis do not coincide and are not
parallel to each other


When the center of the bracket base is
placed on FA point the long axis of the bracket stem
and bracket slot both are parallel to and are in line
with Andrew’s plane. But this is not possible with
brackets having torque in the face


Theoretical effects of torque-in-face on the final
positioning of FA point - The undesirable effects of
having torque in face are in-built errors in finale vertical
positioning.
The absolute magnitude of vertical
displacement will depend upon the torque angle, its
direction (occlusal or gingival) and of course its effect will
be reversed if the torque is also reversed. The only site
however at which the torque direction changes completely
in the standard straight wire prescription is between lateral
incisor (torque = +30) and canine (torque= -70)


Ferguson concluded that the advantages of the
torque in base are largely theoretical, but it should be
kept in mind that there are other advantages. One
such advantage is that the wings of the brackets with
torque in the face could bend under various forces


TORQUE IN VARIOUS STRAIGHT WIRE
PRESCRIPTIONS


TORQUE ADDITION IN MBT
APPLIANCE
1.

Additional palatal root torque for upper incisors
and additional root torque in labial incisors

2.

Upper cuspid brackets with a normal -70 torque
or 00 torque.

3.

Upper molar brackets with an additional 50
buccal root torque.

4.

Progressive Buccal ground torque in the lower
cuspid and lower buccal segments

Note : Reversion of Bracket will reverse the torque prescription
of the bracket but the tip remains the same

PLAY OF THE WIRE IN THE
BRACKET
• What is play ?
•

The difference between the slot with and the
dimension of the arch wire is termed as play

• * For every 0.0010 of play within the bracket slot 40 of
effective torque as slots
• * The amount of the play wire bracket interface is
also influenced by ligation
• *If the wire not fully engaged the effective torque
decreases

* But generally there is some play between the
bracket and arch wire even if the slot is
filled with full dimension wire.
* Because the dimension of the wire will be slightly
smaller than the label dimension and slot
width are larger than they are labeled


TORQUING IN REMOVABLE
APPLIANCES
Various types of torquing springs are used to
bring about root movement or torquing. Normally
they derive their elasticity from the twisting of a
section of wire in the same way as torque bars of
high tensile steels used for suspension systems
in road vehicles
A typical torque springs have the following parts


A A’ :
B B’ :
C C’ :

Fixed firmly in base plate
Torque bars
Apron spring for rotquing

Apron spring derive their main flexibility from
the twisting of the section and the length of the
torque bars. These torque spring are flexible,
easy to construct, easily positioned and adjusted


It is ensure that the torquing springs
act exactly at points intended and do not slide
away to the unsuitable points. For this reason it
is sometimes necessary to make springs rather
stiff in order to ensure accuracy of the application
to the teeth


In 1975 BASS has shown that palatal root
movement is performed by applying pressure in a
lingual direction at the gingival margin on the incisor
and preventing the lingual movement of the crown by
using “Swed bite plane”.
Watkin in 1933 used a box type of attachement
for root movement.
In 1938 McKeag and Friel described a box
attachment made up of stainless steel to induce
torque. This box was well known as “M” Ckeag Box”

CONCLUSION
My rationale on torque is, first give the teeth the
normal look. If you study untreated good occlusions that are
esthetically pleasing, they also function well, so we emulate
that. However, good esthetics does not insure good function.
It’s easy to straighten the upper teeth on the upper jaw and the
lower teeth on the lower jaw, but if the upper and lower teeth
don’t harmonize with each other when the mandible is in centric
relation then function will be poor. This is the most difficult part
of orthodontics, harmonizing the upper and lower teeth to each
other with the mandible in centric relation. If this harmony is
established then the natural “settling-in” of the teeth after the
appliances are removed will produce good function in most
cases. Exceptions to this are open bite type cases which don’t
“settle-in”. Therefore their finished occlusion with appliances
should be more precise

Thank you


Torque and its_application /certified fixed orthodontic courses by Indian dental academy

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