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10 mm 2 mm 4 mm
BETA (POSTERIOR) SEGMENT
5 mm
ALPHA (ANTERIOR) SEGMENT
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• HOW TO USE T LOOPS FOR EXTRACTION SPACE CLOSURE • T-LOOPS vs VERTICAL LOOPS
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HOW TO USE T LOOPS FOR EXTRACTION SPACE CLOSURE
• POSITIONING OF THE LOOP DURING SPACE CLOSURE
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• IN GROUP A ANCHORAGE PLACE THE TLOOP a)offcentered towards anteriors b)offcentered towards posteriors c)centered d)any of the above position
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•
What are preactivation bends? why are they given?
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BIOMECHANICS
•
STATIC EQULIBRIUM PRINCIPLE
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• What is moment to force ratio? What is its significance?
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Consider the moment created when force is applied Mf and the counter balancing moment generated by the couple within the bracket Mc Mc/Mf = 0 –Pure tipping Crot and cres same,thus the tooth rotates around the Cres
0 < Mc/Mf >1- Controlled tipping – Crot displaced away from Cres – crown and root move in the same direction
Mc/Mf = 1– Bodily movement – equal movement of crown and root
www.indiandentalacademy.com Mc/Mf > 1 Torque – root apex moves further than the
MOMENT TO FORCE RATIO FOR VARIOUS TOOTH MOVEMENTS
M/F
5:1
Uncontrolled tipping
M/F
8:1
Controlled tipping
M/F
10 : 1
Translation
M/F
>10 : 1
Root movement
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V - BEND PRINCIPLE
Center bend
Off center bend Long segment
Short segment
No short or long segment
Points in the direction of the force produced on the tooth
Points in the direction opposite of the force produced on tooth
No force produced
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T loop vs vertical loop •
FABRICATED IN TMA WIRE
•
LOW LOAD DEFLECTION RATE
•
HIGH YEILD STRENGTH
•
LESS CONSTANT FORCE
•
HIGHER MOMENT/FORCE RATIO
•
STAINLESS STEEL WIRE
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GROUP B ANCHORAGE Distal force on anteriors
Mesial forces on posteriors
Equal potential for tooth mvt. Alpha moment
EQUAL
Beta moment
Horizontal force acting on both segments are same
Moment to force ratio EQUAL RETRACTION OF ANTERIOR www.indiandentalacademy.com
PROTRACTION OF POSTERIOR
Group B ANCHORAGE CASE
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â&#x20AC;˘ POSITION OF T-LOOP: D = L-A 2 D = Distance from the center of the loop to either the anterior bracket or posterior auxillary tube. L = Distance between the canine bracket and Molar tube. A = The millimeters of activation of the spring (usually 6 mm) www.indiandentalacademy.com
β
α
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GROUP A ANCHORAGE Distal force on anteriors Maximum potential for tooth mvt.
Mesial forces on posteriors Miminised or counteracted Increase moment
Decrease moment
Horizontal force acting on both segments are same
Moment to force ratio Reactive unitwww.indiandentalacademy.com
Anchor unit
Alpha moment
Beta moment
Anteriors
posteriors When unequal or unbalanced Vertical forces created
Extrusion
Intrusion
alpha
alpha
beta
beta
Intrusion
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Extrusion
• GIVE EQUAL ALPHA AND BETA BENDS AND PLACE THE LOOPS OFFCENTERED TOWARDS POSTERIORS • GIVE MORE BETA BEND AND PLACE THE LOOP OFFCENTERED TOWARDS ANTERIORS • GIVE EQUAL ALPHA AND BETA BENDS AND PLACE THE LOOPS AT CENTER AND USE HEADGEAR TO CONTROL THE POSTERIOR SEGMENT www.indiandentalacademy.com
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T LOOP
The preactivated spring with the anti tip and anti rotation BENDS ARE placed Activation on insertion is 6mm The m/f is 8:1 – controlled tipping Now as the tooth moves the activation reduced to 4mm – the force is reduced
M/f ratio is increased - bodily movement further The activation is reduced to 2mm – force is further reduced M/f ratio increased – 12:1 Root uprighting www.indiandentalacademy.com
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ANTI RATIONAL BENDSOPTIONAL
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