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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com

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

Orthodontic treatment prior to and after surgical correction of malocclusion is considered vital to the stability of the achieved result



Pre surgical orthodontics helps the oral surgeon to align the skeletal bases on the operating table www.indiandentalacademy.com


Bracket systems

First generation

Second generation Ronald Roth

1980’s

Third generation

1990’s

Andrews

MBT

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1972




.022 versus .018

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The slot dimension preferred and widely used by the orthodontist for a surgical case is .022 slot, the stability is better as it allows the use of stiffer wires.

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Frictionless mechanics

Anterior segment Vs posterior segment

Friction mechanics

Anterior segment Vs posterior segment + Friction Increased anchorage demands

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Inbuilt tip VS expressed tip

Inbuilt tip - The tip built into the bracket

Expressed tip – on insertion of wire – the change in the mesio distal inclination of tooth

The effect of the inbuilt tip and expressed tip on the mesiodistal inclination of teeth is very minimal. www.indiandentalacademy.com


 

Inbuilt torque and expressed torque loss of torque – cardinal rule

For every 0.001” play there is loss of 40 loss of torque

PAE is highly inefficient in regaining lost torque www.indiandentalacademy.com


7

6

5

4

Roth

00

00

00

00

MBT

00

00

00

00

3

2

1

Roth

+130

+90

+50

MBT

+80

+80

+40

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7

6

5

4

Roth

-140

-140

-70

-70

MBT

-140

-140

-70

-70

3

2

1

Roth

-20

+80

+120

MBT

-70,00, +70

+100

+170

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Tip

7

6

5

4

Roth

-10

-10

-10

-10

MBT

00

00

+20

+20

3

2

1

Roth

+70

+20

+20

MBT

+30

+00

+00

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7

6

5

4

Roth

-300

-300

-220

-170

MBT

-100

-200

-170

-120

3

2

1

Roth

-110

-10

-10

MBT

+6,0,-60,

-60

-60

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Palatal root torque on the anterior and posterior region

Anterior region – desirable Posterior region - undesirable

Distal to the laterals – buccal root torque www.indiandentalacademy.com


Posterior

Anterior

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Skeletal mal- relationship Teeth compensate to mask the skeletal discrepancy Pre- surgical orthodontics Eliminate the dental compensation that has occurred with respect to the skeletal base www.indiandentalacademy.com


Objectives 

Co-ordinate the arches in transverse dimension

 Leveling  Class

II molar and canine relation ship

 Obtain

sufficient over jet

Treatment plan

Mechanotherapy

Anchorage preparation www.indiandentalacademy.com


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Objectives 

To coordinate the arches in transverse dimension

Leveling

Class III molar and canine relationship

Reverse overjet&

Treatment plan

Mechanotherapy

Anchorage preparation

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Objectives 

Coordinate arches in the transverse dimension

Leveling

Divergence of roots at the planned osteotomy site

Treatment plan

Mechanotherapy

Anchorage preparation

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Segmental mechanics are more Bioefficient with less adverse effects

Statically determinate system – thus possible to know the exact amount of forces and moments in the system

Though continuous mechanics is a statically indeterminate system, it has been widely preferred by the orthodontist due to the easy cookbook approach. www.indiandentalacademy.com


Aligning by a segmental approach at the osteotomy site – most beneficial Altering the height of the bracket positioning to achieve the extrusion of the to be intruded segment Use of a stainless steel or a TMA spring to create a step at the osteotomy site which TMA is preferable  

Achieve stabilization of posterior segment with stainless arch wire Insert the spring into the auxiliary tube www.indiandentalacademy.com


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Tip

Torque

Mesio distal diameter (Bolton’s ratio)

Curve of spee www.indiandentalacademy.com


•Consistency •Accuracy •Predictability •Convenience

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Change in tip alters the mesio distal diameter occupied www.indiandentalacademy.com


Space closure Lower arch the complete space closure achieved

Inability of complete space closure in the upper arch

Loss of torque www.indiandentalacademy.com


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Learn to appreciate the concept of inbuilt tip and torque versus expressed tip and torque

Develop individual orthodontic sense instead of blindly following prescription and bracket systems

Having a thorough knowledge of biomechanics involved will help the orthodontist to supplement any deficiency present in the system that is being used www.indiandentalacademy.com


Thank you www.indiandentalacademy.com Leader in continuing dental education

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