Post on 25-Apr-2017
Bracket Positioning, Sequence of Mechanics
in Edgewise Mechanics
INDIAN DENTAL ACADEMY
Leader in continuing dental education www.indiandentalacademy.com
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Bracket Positioning, Sequence of Mechanics
in Edgewise Mechanics
Dr. OP Kharbanda, AIIMS, New Delhi
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Basics of Edgewise
Dr. O. P. KharbandaAll India Institute of Medical Sciences
opk15@hotmail.com, ompk@aiims.ac.in www.indiandentalacademy.com
Dr. Ashok Jena, Dr. Sandip Kumar,Dr. Priyanka Kapoor, Dr. Hari,Dr. Neeraj Wadhawan, Dr. Vishal Gupta, Dr. Anand Pal Lohia
Contributors
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Growth trends
– Type A growth trend– Type B growth trend– Type C growth trend
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Type A growth trend• The middle and lower face are growing forward and
downward in unison, with no change in size of the ANB
• Growth is approximately equal in both the vertical and horizontal dimensions
• Approximately 25 % of patients
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Type B growth trend• Growth downward and forward with the middle face
growing forward more rapidly than the lower face• Growth of the middle and lower face is predominantly in the
vertical dimension in most instances • ANB reading 60 to 120
• If ANB is less than 40 prognosis is fair• If ANB is 70 to 120 prognosis is poor• Extraction of all four first premolar mandatory for patients
with high ANB angle• Only about 15% patients www.indiandentalacademy.com
Type C growth trend• Lower face is growing downward and forward more rapidly than
the middle face with a decreases in ANB angle• When FMA ranges upward from 200, growth is approximately
equal in the vertical and horizontal dimensions• When FMA 200 or less, growth predominantly horizontal• When growth is virtually confined to the horizontal dimension
with little vertical growth, the growth trend is classified as Type C subdivision.
• 60% patients have Type C growth trend
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Anchorage• Tooth anchorage (Anchorage preparation)• Anchorage savers Anchorage preparation• 1st degree• 2nd degree• 3rd degreeAnchorage savers• Headgear or palatal bar• Nance button• Delayed extraction• Lip bumpers• Muscular pattern of low FMA cases
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Anchorage saversDr. OP Kharbanda www.indiandentalacademy.com
Bracket placement• Precision bracket placement is essential for good leveling
and alignment.
• Indirect bonding showed better bracket placement. (Koo, Chung, Vanarsdall, 1999)
• Light cure bonding also showed better bracket placement than chemical cure.
• Bonding with orthocad technology shows more accurate bracket positioning.
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Bracket placementTweed: Mandibular arch: • Bracket slot should be 3.5mm from incisal edge or cuspal tip • On molars -Between occlusal and middle thirdMaxillary arch:• Bracket slot 3.5mm from incisal edge of cuspal tip except on lateral
incisor (3.0mm)
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Bracket placementLindquist:
Upper arch Lower arch
Central 4.5mm 4.0mm
Lateral 4.0mm 4.0mm
Canine 5.0mm 4.5mm
Premolar 4.5mm 5.0mm
Molar 3.5mm 4.0mm
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Computerized bonding• Generating digital information defining the shape and
location of the malocclused tooth with respect to the patient's jaw
• Generating a mathematical model of the malocclused tooth as positioned in the jaw from the digitized information
• Calculating the finish position in the jaw to which the malocclused tooth is to be moved from the digitized information
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Computerized bonding
• Calculating the placement position of an orthodontic bracket on the malocclused tooth required in order to move the malocclused tooth to its finish position by a preselected orthodontic treatment
• A standard bracket is thereafter modified, if desired, individually for the patient, in view of the patient's physical deviations from the statistical averages.
• The shape of a bracket positioning jig is calculated and formed
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ALIGNMENT & LEVELING
Goals of first phase
• Bring the teeth in alignment and correct vertical discrepancies by leveling out the arches
• Labiolingual discrepancies (crossbites)
• Axial discrepancies (mesio-distal)
• Correct rotationswww.indiandentalacademy.com
Loop mechanics
• A loop reduces force and increases range by adding wire in inter-bracket span.
• A loop may be open or closed type.• Open loops are most efficiently activated through
compression of the legs.• The force of any loop may be reduced by coiling the wire
at the apex one or more times.• The force developed in loop or arch wire is transmitted to
the tooth through the bracket attachment resulting tooth movement.
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Clinical applications of loops
Movements Loop
Labial - Double vertical- open
Lingual - Double vertical- open
Elevation - Double horizontal or Box
Depression - Double horizontal or Box
Rotation - Double vertical- open or box
Root tipping- Box or double horizontal
Canine Retraction – Ricketts Spring
Incisor Retraction T loops /double key hole loops
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Clinical applications of loops1. Mesial or distal movement (such as midline correction): double
vertical loop against bracket or fixed to the contained section of the arch, activated by tying back or compression. Combination of open and closed vertical loops.
2. Space closure (contraction of the arch): closed vertical loop, tied back.
3. Space opening (expansion of the arch): open vertical loop, with stops.
4. Bite opening: T-loops mesial to the canine. Note that the arch wire in anterior section between the two loops should have reverse curve to transmit the pressure equally to all 4 incisors.
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Principles in the choice of alignment arches
• Initial arch wires for alignment should provide light, continuous forces to produce the most effective tooth movement. Heavy force in contrast should be avoided.
• The arch wire should be able to move freely within the brackets. For mesiodistal sliding along an arch wire, at least 2 mil clearance between the arch wire and bracket is needed, and 4 mil clearances is desirable.
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Principles in the choice of alignment arches
• Rectangular wire particularly those with a tight fit within the bracket
slot so that the position of the root apex could be affected, normally
should be avoided. Cupper Ni Ti or BioForce are the exceptions.
• Round wires are preferred for alignment.
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Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Multiple loop arch wire (0.016”)Molar tie back,Vertical loops, L loops
Upper
Lower
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos courtesy Dr.Hari PG student www.indiandentalacademy.com
Multiple loop arch wire after ligation
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student
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Multiple loop arch wire after movement
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Leveling with 0.016” Arch wireMolar stops
First order bendsSecond order bends
upper
lower
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student
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0.016” Arch wire after ligation
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
0.016” Arch wire after movement
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Leveling with 0.018” Arch wireMolar stops, First order bends, Second order bendsCurve of spee- upper, Reverse curve of spee- lower
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Typical Upper and lower leveling wire often used in Edgewise appliance just beforeInsertion of the Edgewise wire.
Mild curve of Spee With tip back bends andMolar stops
Mild Reverse curve of Spee With tip back bends and molar stops
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Leveling with 0.020” Arch wire
• Molar stops
• First order bends
• Second order bends
• Curve of spee- upper
• Reverse curve of spee- lower
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Acknowledgement Sincere thanks to all those staff , PG students, CMET Staff and all
others who have directly or indirectly contributed to this presentation
Dr. OP Kharbanda, AIIMS, New Delhi, Typo Photos Courtesy Dr. Hari PG student www.indiandentalacademy.com
Thank you
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