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The Second stage of comprehensive treatment: correction of m

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Christine Chny

on 18 March 2014

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Transcript of The Second stage of comprehensive treatment: correction of m

Correction of Molar Relationship
1) Differential Growth in Adolescent Class II Treatment
2) Correction by Distal Movement of Upper Molars
3) Differential Anteroposterior Tooth Movement Using Extraction Spaces
4) Molar Correction with Inter-arch Elastics
Differential Growth in Adolescent Class II Treatment
Girls mature earlier than boys
Use of extraoral force and or functional appliances
To modify growth in Class II patients, both for restraint of maxillary growth and differential mandibular growth
Distalization of First Molars After Second Molar Extraction
3 possibilities:
1) Headgear
2) Palatal anchorage
3) Skeletal anchorage
Palatal Anchorage Systems for Distal Movement of Molars
The relative stability of the anterior palate, both the soft tissue rugae and the cortical bone beneath them
Objectives
To correct molar and buccal segment relationships
Close extraction spaces or residual spaces in the arches
To correct excessive or negative overjet

Correction by Distal Movement of Upper Molars
1) Class II elastic treatment
2) Palatal anchorage
3) Skeletal anchorage (bone screws or bone anchors)
The Second stage of comprehensive treatment: correction of molar relationship and space closure
Christine Joy S. Chny, DMD
IDeal PAtient
A 12- to 14-year-old boy with a Class II problem with skeletal maturity somewhat behind dental development.
Has good growth potential
molar rotation as a factor in distalization
Mild-to-moderate skeletal Class II malocclusion
The upper molars are likely to have rotated mesially around the lingual root
And merely correcting the rotation changes the occlusal relationship in a Class I direction
Transpalatal lingual arch
An auxiliary labial arch
Inner bow of a facebow
Generating of molar distalzing force:
1) A-NiTi coil springs
2) Magnets in repulsion
3) Pendulum appliance
Magnets in Repulsion
Pendulum appliance
Unilateral molar distalization is indicated
Unilateral Class II malocclusion is present
Dental midline discrepancy
Extraction of 1 upper 2nd molar and asymmetric cervical headgear
Differential Anteroposterior Tooth Movement Using Extraction Spaces
(1) to provide space to align crowded
incisors without creating excessive protrusion
(2) to allow camouflage of moderate Class II or Class III jaw relationships when correction by growth modification is not possible.
Deciding which teeth to extract and how the extraction spaces are to be closed (i.e., by
retraction of incisor teeth, mesial movement of posterior teeth, or some combination).
important
Class II Camouflage by Extraction of Upper First Premolars
The objective is to maintain the existing Class II molar relationship, closing the first premolar extraction space largely by retracting the protruding incisor teeth
Excessive maxillary incisor protrusion and persistent Class II molar relationship
Extraction of Maxillary and Mandibular Premolars
Class II elastics will be used to assist in closing the extraction sites
begg technique
Light interarch elastics
Class II elastics
Anchor bend
Maxillary anterior teeth- to tip back
Mandibular arch- to control the amount of mesial tipping of molars
2nd stage of Begg treatment
Edgewise appliance
Mesiodistal width of canine brackets tend to keep the canine teeth more upright
The best control is achieved with the segmented arch technique, using space-closing springs
edgewise appliance
A more common approach with the edgewise appliance is to extract maxillary first and mandibular second premolars, thus altering the anchorage value of the two segments
Molar Correction with Interarch Elastics
Without extraction spaces, Class II elastics produce molar correction largely by mesial movement of the mandibular arch, with only a
small amount of distal positioning of the maxillary arch, and can produce far too much protrusion of lower incisors
Class II elastics produce not only anteroposterior and transverse effects
but also a vertical force
This force elongates the mandibular molars and the maxillary incisors, rotating the occlusal plane up posteriorly and down anteriorly.
If the molars extrude more than the ramus grows vertically, the mandible itself will be rotated downward
closure of extraction spaces
1) Moderate Anchorage Situations
Moderate Anchorage Treatment with 18-Slot Edgewise: Closing Loops
3 major characteristics:
A) Spring properties (the amount of force it delivers and the way he force changes as the teeth move)
B) Moment
C) Location relative to the adjacent brackets
spring properties
Determined by:
Wire material (steel or beta-titanium)
Size of the wire
Distance between points of attachment
root-paralelling moments
To close an extraction space while producing bodily tooth movement, a closing loop must generate not only a closing force but also appropriate moments to bring the root apices together at the extraction site.
Closing loop should be sringier
Placing some of the wire within the closing loop in a horizontal rather
than vertical direction improves its ability to deliver the moments needed to prevent tipping.
Location of the loop
Only if it is in the center of the span does a V-bend produce equal forces and couples on the adjacent teeth
If it is one-third of the way between adjacent brackets, the tooth closer to the loop will be extruded and will feel a considerable moment to bring the root toward the V-bend, while the tooth farther away will receive an intrusive force but no moment
Clinical recommendations
It is important to activate the upper horizontal portion of a delta or T-loop so that the vertical legs are pressed lightly together when the loop is not activated.
This also ensures that the loop will still be active until the legs come into contact.
A gable bend of approximately 20 degrees on each side is needed to achieve an appropriate ratio between
the moment-force ratio
Moderate Anchorage Space Closure with 22-Slot Edgewise
2 steps to better control posterior anchorage:
1) retracting the canines, usually sliding them along the archwire
19x25 or 18x25 archwire
2) retracting the four incisors, usually with a closing loop
18x25 steel wire with T-loop
19x25 beta-Ti wire
If en masse space closure is desired with the 22-slot appliance, a segmented arch technique is indicated.
A retraction spring is used to connect these stable bases, and the activation of the spring is varied to produce the
desired pattern of space closure.
maximum retraction with the 18-slot appliance
I. Reinforcement with Stabilizing Lingual Arches (Rigid 36 mil or 32x32 steel wire)

II. Reinforcement with Headgear and Interarch Elastics (Extraoral force against the maxillary posterior segments and Class III elastics)
III. Segmented Retraction of the Canines (Frictionless springs)
maximum incisor retraction (maximum anchorage)
maximum retraction with the 22-slot appliance
I. Reinforcement of Posterior Anchorage with Extraoral Force (Headgear for maxillary arch and Class II elastics off the headgear to reinforce retraction of lower canines)
II. Segemented Arch Mechanics for Canine Retraction
III. Segmented Arch Mechanics for Tipping/Uprighting
minimum incisor retraction
Reinforcement of anchorage of anterior teeth and reduction of strain on that anchorage
Active Lingual Root Torque in the incisor section of the archwires
Breakdown the posterior anchorage by moving the posterior teeth forward one tooth at a time
Skeletal anchorage or bone screw behind the canines to bring posterior teeth forward
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