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
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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
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.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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