Biomechanics in bagg /certified fixed orthodontic courses by Indian dental academy

STAGE II
BIOMECHANICS IN
BEGG’S APPLIANCE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


•
1.
2.
3.
4.
5.

Only after achieving all the requirements of
Stage I ie.
Alignment.
Elimination of crossbites.
Correction of overjet & overbite.
Midline correction
Attaining Class I molar & canine relation.
Stage II should be commenced.

Why Stage II is necessary?
To prevent the posterior teeth from moving
too far mesially.There would be insufficient
space left to move anterior teeth.
As it cannot be predicted how rapidly & to
what extent posterior teeth will move
mesially, it is unsafe to commence closure
of spaces at the start of the treatment
even in mild discrepancy cases.

BIOMECHANICS


Differential is defined as the difference of
two or more motions or pressures.
Tooth movement = force x time
resistance
The amount of force required to move teeth
is in positive ratio to the surface area of the
tooth root attached to the bone by the
periodontal membrane.

In this technique advantage is taken of the
principle, that , for moving anterior teeth with
small root surface area , relatively light arch wire
and rubber elastic force produce the most rapid
movement with least disturbance to investing
tissue.
Also at the same time the light forces keep the
anchor molars stationary.
Conversely relatively large force causes the
anterior teeth to resist the force, so that anterior
force operate as anchor unit, as they move very
slowly, while this large force causes the
posterior teeth to move rapidly.

In an interdental force system (one that uses
no auxiliaries, such as headgear and bite
plates) the only appliance forces are those
exerted between one or more teeth and one or
more other teeth.
In keeping with Newton's third law, these
forces can only be equal and opposite. They are
differential only in that they are exerted in
opposite directions.

When these forces are exerted, they encounter tissue
resistance, and it is tissue resistance that exhibits
the differential response to equal and opposite forces
which results in differential tooth movement.

Simple crown tipping, for example, encounters little
resistance and responds rapidly, but root tipping or
bodily movement meets with high resistance and
responds slowly.


Whether there is an optimum orthodontic force
that will give best results , move the teeth at
most favorable rate and with least tissue
damage and pain?

Storey and Smith concluded that there is an
optimum range of force values that produces a
maximum rate of distal movement of canines,
and this optimum force did not produce any
deleterious movement of the molar anchor unit.

• To move the canines distally 150-200 gms of
force is the optimum range.
• Maximum rate of mesial movement of molars
occurred when force was increased to300-350
gms.
• When force was below 150 gms for canine &
below 300 gms for molars neither tooth
movement occurred.
• When heavy springs were activated , very little
or no movement of canine occurred, instead
molars moved mesially in remarkable fashion.


When Dr.Begg adopted the principle of differential
resistance for tooth movement in the first two stages, he
took advantage of the significant difference between the
types of resistance used and the amounts of force required
to overcome them.


• Differential Force For Closing Extraction
Space:
According to Strang during closure of first
premolar extraction space with edgewise
mechanism, most of the space is closed
by forward movement of anchor teeth
instead of distal movement of canines.
Failure was not due to inability to
prevent anchorage but due to excessive
force.
So, according to Dr. Begg investigation
made by Storey & Smith on light
orthodontic force value is optimum to
prevent any anchor loss, And is
physiological.www.indiandentalacademy.com

In stage II the six anterior teeth are banded .
Only first permanent molars are banded for
anchorage.
On each side . A light rubber elastic is
stretched from the distal free end of arch wire to
the intermaxillary hook
The extraction space close rapidly , & anchor
tooth hardly moves forward.
To close remaining posterior spaces heavy
elastic force is used to move the molars.
Braking auxiliaries are used to prevent further
distal movement of anterior teeth.

ARMAMENTARIUM USED
IN STAGE II


Second stage Safety lock pins
• Shoulder on labial surface of head
ensure
free mesiodistal tipping.
• Lab-lin width of pin(0.020”) reduced
0.004” as compare to stage 1 pins to
permit use with 0.018”or 0.020” inch
wire.

Archwires
0.018/0.020” arch wires used.
Only function – to maintain the corrections –
achieved. ( bite opening, arch form & tooth
alignment.).
Stabilize the teeth against –Reciprocal forces –
application of elastics or auxiliaries.


Objectives of Second Stage
Maintain all corrections achieved during stage I.
 M-D molar relationship maintained .
 Original spaces b/w ant. teeth prevented from
recurring – tying IM circles to cuspid brackets.
Over rotations


of cuspids maintained – engaging brackets – offset on the
teeth.


Objectives of Second Stage
 of bicuspids held – replacing elastic threads
with steel ligature ties.
 of Central and lateral incisors – maintained –
continued use of bayonet bends in the archwires.
Bite opening maintained – continued use of bite opening
bends & elastics.
Correction of posterior crossbite maintained – modifying
archwire or cross elastics.
Close any remaining posterior spaces.
 Wearing of horizontal elastics.

Commencement of stage II –
Lateral ceph & stage models.
Intraoral photographs.

Lateral Ceph. compared with that of original
radiograph.





antero posterior tooth movements in ref
to each other & to face & cranium.
anchorage maintained properly.
inclination of the anterior teeth.

Anchorage bend


in comparison with that given in the

stage I.
Location:These are located 3mm in front of the mesial
end of molar tube, approximately at the junction
between the distal of the second premolar &
mesial of fist molar.

Inserting and activating archwires
Insert and check
Degree of anchorage bend –
- adequate to resist forward pull of elastics.
- rest passively – halfway b/w brackets & mucolabial
fold.
Distal ends of the archwires –
1 – 2 mm beyond the distal end of the tubes.
Anchorage bends sufficiently forward
Toe-in bend is given to prevent molar rotation.

Horizontal or intramaxillary elastics for space closure.

. Class II elastics –
- relieved of correcting over jet.
- used to maintain overcorrected
positions of ant. & post. teeth

Six elastics worn simultaneously.

Problems encountered with elastic wear


Tooth movements carried out during the 2nd
stage of treatment
Spaces in the buccal segment to be closed.
Extn. space of four first premolars.
Congenital absence of 2nd P.M.
Lost buccal teeth due to caries.
Spaces b/w teeth in Non-Extn cases.

Exception.
Extreme tooth spacing – small tooth size.

Auxillaries sometimes used in
stage II


• Braking Auxillary make two point contact & prevents
more distal tipping of the canines, so anterior segment
becomes anchor unit and prevent further retraction.
• Excessive force causes hyalinized tissue formation on
the lingual side of anterior teeth which prevents tooth
movement.
• Posterior teeth having larger roots more force is required
to move them mesially.

Teeth positions at the end of Stage II
Extraction spaces closed.
Crowns of upper and lower ant. teeth –
tipped back or ‘dished in’.


Disadvantages of Conventional Begg
Round wire – Ribbon bracket combination – no precise control
for fine finishing.
True intrusion of upper incisors – nil or minimal.
Overuse of Class II elastics
Lack of upper incisor intrusion.
Undesirable proclination of lower incisors.
Tipping of mandibular & occlusal planes.
Uncontrolled tipping –
root resorption.
long third stage.

REFINED BEGG
STAGE II

Stage II Auxillary:
MAA auxillary.
Base wire – 0.020”.
Premium, premium+, supreme – in the
order of increasing yield strength.
Superior properties  pulse straightening,
as against spinner straightening of older
grades.
Brakes to avoid excessive incisor tipping.

ELASTICS
•Yellow(5/16”) classI or classII elastics are
used for anterior retraction.
•Green(5/16”) is used for posterior protraction
•Blue(1/4”) or Red(3/16”) is seldom used ,only
when green elastics are found in effective in
low mandibular plane angle cases.

Essentials of Begg – Unaltered
 Light orthodontic forces.
 Crown tipping + Root tipping

bodily movement with least

taxation on anchorage.
 Brackets – free tipping in initial stages.
 Differential forces.
 Sequence of trt. stages.

Essentials of Begg – Unaltered
Light intra-oral elastic force.
Over corrections of all displacements.
Use of round high tensile wires.


Stage II
Objectives----Common –
– Maintain all corrections – in stage I.
– Close all extraction spaces.

Additional.
– Controlled tipping – space closure – ant.
retraction.
– Prevent excess tipping – efficient brakes – space
closure by protracting post.

Archwires in Stage II of Refined Begg
In extn. & non extn. cases –
0.018” P or P+, or 0.020” P wires.
If stage corrections involved – extreme deep bite, badly
distorted arch forms or severe rotations – 0.020 archwires
effective.
Anchor bends
PM bypassed – except when in distobuccal rotation.

Controlled tipping of the incisors
MAA – lingual root torque – controlled lingual tipping
– incisors during retraction.
Lower incisors – labial root torque by MAA auxillary.
Canines – excess tipping – 0.010 uprighting springs.


BIOMECHANICS OF MAA
UPPER ARCH

• Moment caused by intrusive force – crown labial, root
lingual.
• Moment caused by reactive force – crown lingual, root
labial.
• Moment produced by intrusive force counteract moment
produced by reactive force.
Controlled tipping occurs.
• If intrusive force iswww.indiandentalacademy.com elastic force is
inadequate, or the
large, M/F ratio will be inadequate for controlled tipping.

• MAA causes same couple as generated by
intrusive force from base arch wire i.e..
crown labial, root lingual.
• Moment produced by MAA counteract
moment produced by reactive force.
controlled tipping occurs.

LOWER ARCH

•MAA is used for lingual root torque may
be required to prevent uncontrolled crown
lingual-root labial tipping of lower incisors.


Braking mechanics
Cases – excess space closed by post.
protraction.
Good profile at start of treatment.

‘Brakes’ – reverse anchorage site.


Braking springs: passive uprighting springs
– 0.018 wire.

Angulated T pins: prevent further tipping

Commonly used:
Braking springs: passive uprighting springs – 0.018
wire.
Angulated T pins: prevent further tipping

Combination wires: either of SS or Alpha
Ti alloy.
Ant segment. – 0.022 x 0.018 (ribbon
mode).
Post. segment – 0.018 round .
Alpha Ti – easier to engage in ant.
br. slots. chance of distortion.
Use SS combination wire - torque
than alpha Ti.
Disadvantage – expensive.

SS 0.022 x 0.018 sectionals – torqued in
ribbon mode – piggy back over 0.018
base wire.


Check list
• Spaces closed completely.
• Anterior edge to edge bite or +ve overjet in open bite
cases.
• Canine & molar relations – Cl I or super Cl I


Conclusion
 Through the use of the optimum orthodontic
force ie, one that moves the teeth most rapidly,
with least discomfort to the patient and with least
damage to the teeth and their investing tissues,
effective space closure is achieved with
minimum taxation of anchorage.
 Teeth are left in the proper position to be
uprighted and put into good axial relation in the
third stage.

Biomechanics in bagg /certified fixed orthodontic courses by Indian dental academy

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