Elastics in orthodontics
Definitions
Elasticity : it is the property of a material to return to its initial shape after the action of a distorting force.
Elastic material:
It generally has 3 properties:
A distortion capacity that does not go beyond the elastic limit
A property of physical homogeneity
An isotropic property, therefore capable of delivering the same force in any
which direction.
CLAPEYRON’s reciprocity theorem :
When an elastic force is applied to two identical solids (e.g. the
two central incisors) the displacement force is identical and reciprocal.
Elastomers
It is a general term encompassing materials capable of returning to their original dimension immediately after the cessation of the substantial distorting force. Under the term elastomers are included natural rubbers or latexes derived from the rubber tree.
Class I elastics
Definition :
Class I elastic can be a chain, a rubber ring or a wire placed
only on one arch and having a vertical or horizontal force movement.
Class I elastic has a reciprocal biomechanical action in a straight line without any other
component.
Arrangement :
Class I elastic can be placed:
+ From one tooth to another
+ On a tooth in a manner opposite to the force torque
+ From a tooth to an arch, or a loop
+ From one point to another of an arc
+ From one tooth to) an axillary appliance such as a Quad’helix, a bar
palatine, a palatine plate,…
Class I elastic is a monomaxillary or monomandibular elastic which
can be used in conjunction with other elastics.
Clinical application of Class I elastics
The applications are numerous:
Space closure such as diastema, Class I elastic is used as
contraction system
Dental movement of retraction of a tooth or advancement of a segment
posterior.
Extrusion: of a single tooth in an ectopic position (vestibular or palatal)
Intrusion of the incisors (the elastic is placed on a reciprocal arc of 0.45)
Fixed the version of a dental axis.
Pr. AHMED FOUATIH. N 1
Class II elastics.
Definition
Class II elastics are anteriorly placed intermaxillary elastics
on the maxilla, and posteriorly on the mandible.
Arrangement
Class II elastics can be placed at both:
The mandibular arch posteriorly on the vestibular, lingual or
two at a time on:
Different teeth M2, M1, Pm2, Pm1.
The distal part of the molar tube
A hook
A loop
A JARABAK or KAYABASHI ligature
A vestibular hook coming from a lingual arch
A palatal plate with a distal hook
And to the maxillary arch anteriorly on:
A sectional arch
A Class II utility bow
A continuous arch with a front loop
A mobile hook
A ligation of JARABAK and KAYABASHI
A case with hook
A Jig
A Class II extra oral force
A reciprocal arc of 0.45 with hook
A mini reciprocal slingshot.
Action of class II elastics on continuous arches
The different actions of Class II elastics on continuous arches are:
Action on the maxillary arch:
The maxillary arch recedes distally
The anterior occlusal plane undergoes occlusal extrusion
The upper incisors become more vertical
All teeth are distalized
Action on the mandibular arch
The lower arch as a whole undergoes a
mesial translation
The lower molar makes an occlusal extrusion with
coronal mesial version
The lower incisors tilt vestibularly
Action on the occlusal plane
The Class II relationship is corrected sagittally
The anterior occlusal plane tilts downward.
Action on the facial pattern
The mandible rotates posteriorly
The chin juts out
Pr. AHMED FOUATIH. N 2
| Lower facial height increases with the intensity of force used and the duration of wearing the elastic. |
Indications for Class II elastics
Class II elastics are used for primary or secondary purposes.
following each clinical case for:
+ Skeletal and/or dental Class II malocclusions
+ Anchor reinforcement
+ Distal movement of the upper incisors
+ Advancement of the mandibular arch
+ The opening of the joint
+ The vestibular version of the lower incisors in retrusion
+ Correction of the deviation of the median lines
+ Double occlusion correction.
Class III elastics.
Definition
Class III elastics are anteriorly placed intermaxillary elastics
on the mandible, and posteriorly on the maxilla.
Arrangement
Depending on the clinical problem, Class III elastics can be attached:
Subsequently:
On the vestibular side
On the palatal side to aid expansion
On the vestibular and palatal side to increase strength
From the distal part of the arch
From a molar hook
Before the maxillary molar, or from the 2nd or 1st PM
From a class III extra oral arch
From a distal hook placed on a palatal plate.
Previously:
A loop on a bow
From a ligature of JARABAK and KAYABASHI
From anterior hooks placed on an inclined plane overbite plate
to help with articulated jumping
Action of class II elastics on continuous arches
The use of Class III elastics has different actions:
Action on the maxillary arch:
Slight maxillary advancement
Advancement with mesial version and extrusion of the 1st
molar
Vestibular version of the upper incisors
Action on the mandibular arch
Distalization of the lower arch
Extrusion of lower incisors
The lower incisors tilt lingually
Pr. AHMED FOUATIH. N 3
Action on the occlusal plane
The Class III relationship is corrected sagittally
The antero-inferior occlusal plane tilts upwards.
Action on the facial pattern
The mandible rotates posteriorly
The chin goes down and back
The lower facial height is increased.
Indications for Class III elastics
-In cases of skeletal patterns of vertical insufficiency
– In vertically normal Class III cases
– In cases of skeletal patterns of vertical excess, treatment must obviously include
surgery.
Finally, the indications for class III elastics concern:
+ Class III dental problems of skeletal patterns
vertical insufficiency
+ Anterior crossbites with incisor end-to-end relationship
centered
+ Retromaxillary with hypo divergence
+ Cases of cl III with incisor overbite facilitating camouflage
by posterior mandibular rotation
+ Mandibular incisor protrusions requiring retraction and
closing of incisal spaces
+ Maximum mandibular anchorage with single-phase extractions
mandibular first premolars
+ Correction of midline deviation
Elastics in orthodontics
Clinical application of Class III elastics
In order to better determine the prognathic patient of class III at risk, do not forget
to use the long-term growth forecast
In cases of vertical insufficiency it is useful:
+ Pro traction of the maxillary arch
+ To tilt the maxillary incisors
+ Use an inclined plane overbite plate with elastics
of class III
+ Use an “M” utility loop to advance the upper arch
+ Use brackets with root-vestibular torque on the incisors
lower to prevent extrusion and lingual version of the force
elastic (to prevent gum dehiscence)
In borderline cases or in vertical excess it is useful
+ Segment the maxillary arch behind the 1st upper molar
+ Keep the rear shims
+ Avoid increasing the vertical direction
+ Use the short cl III anterior closure elastics
+ Check and monitor the ATM
Elastics in orthodontics
Deep cavities may require root canal treatment.
Interdental brushes effectively clean between teeth.
Misaligned teeth can cause chewing problems.
Untreated dental infections can spread to other parts of the body.
Whitening trays are used for gradual results.
Cracked teeth can be repaired with composite resins.
Proper hydration helps maintain a healthy mouth.
Elastics in orthodonticsElastics in orthodontics
Definitions
Elasticity : it is the property of a material to return to its initial shape after the action of a distorting force.
Elastic material:
It generally has 3 properties:
A distortion capacity that does not go beyond the elastic limit
A property of physical homogeneity
An isotropic property, therefore capable of delivering the same force in any
which direction.
CLAPEYRON’s reciprocity theorem :
When an elastic force is applied to two identical solids (e.g. the
two central incisors) the displacement force is identical and reciprocal.
Elastomers
It is a general term encompassing materials capable of returning to their original dimension immediately after the cessation of the substantial distorting force. Under the term elastomers are included natural rubbers or latexes derived from the rubber tree.
Class I elastics
Definition :
Class I elastic can be a chain, a rubber ring or a wire placed
only on one arch and having a vertical or horizontal force movement.
Class I elastic has a reciprocal biomechanical action in a straight line without any other
component.
Arrangement :
Class I elastic can be placed:
+ From one tooth to another
+ On a tooth in a manner opposite to the force torque
+ From a tooth to an arch, or a loop
+ From one point to another of an arc
+ From one tooth to) an axillary appliance such as a Quad’helix, a bar
palatine, a palatine plate,…
Class I elastic is a monomaxillary or monomandibular elastic which
can be used in conjunction with other elastics.
Clinical application of Class I elastics
The applications are numerous:
Space closure such as diastema, Class I elastic is used as
contraction system
Dental movement of retraction of a tooth or advancement of a segment
posterior.
Extrusion: of a single tooth in an ectopic position (vestibular or palatal)
Intrusion of the incisors (the elastic is placed on a reciprocal arc of 0.45)
Fixed the version of a dental axis.
Pr. AHMED FOUATIH. N 1
Class II elastics.
Definition
Class II elastics are anteriorly placed intermaxillary elastics
on the maxilla, and posteriorly on the mandible.
Arrangement
Class II elastics can be placed at both:
The mandibular arch posteriorly on the vestibular, lingual or
two at a time on:
Different teeth M2, M1, Pm2, Pm1.
The distal part of the molar tube
A hook
A loop
A JARABAK or KAYABASHI ligature
A vestibular hook coming from a lingual arch
A palatal plate with a distal hook
And to the maxillary arch anteriorly on:
A sectional arch
A Class II utility bow
A continuous arch with a front loop
A mobile hook
A ligation of JARABAK and KAYABASHI
A case with hook
A Jig
A Class II extra oral force
A reciprocal arc of 0.45 with hook
A mini reciprocal slingshot.
Action of class II elastics on continuous arches
The different actions of Class II elastics on continuous arches are:
Action on the maxillary arch:
The maxillary arch recedes distally
The anterior occlusal plane undergoes occlusal extrusion
The upper incisors become more vertical
All teeth are distalized
Action on the mandibular arch
The lower arch as a whole undergoes a
mesial translation
The lower molar makes an occlusal extrusion with
coronal mesial version
The lower incisors tilt vestibularly
Action on the occlusal plane
The Class II relationship is corrected sagittally
The anterior occlusal plane tilts downward.
Action on the facial pattern
The mandible rotates posteriorly
The chin juts out
Pr. AHMED FOUATIH. N 2
| Lower facial height increases with the intensity of force used and the duration of wearing the elastic. |
Indications for Class II elastics
Class II elastics are used for primary or secondary purposes.
following each clinical case for:
+ Skeletal and/or dental Class II malocclusions
+ Anchor reinforcement
+ Distal movement of the upper incisors
+ Advancement of the mandibular arch
+ The opening of the joint
+ The vestibular version of the lower incisors in retrusion
+ Correction of the deviation of the median lines
+ Double occlusion correction.
Class III elastics.
Definition
Class III elastics are anteriorly placed intermaxillary elastics
on the mandible, and posteriorly on the maxilla.
Arrangement
Depending on the clinical problem, Class III elastics can be attached:
Subsequently:
On the vestibular side
On the palatal side to aid expansion
On the vestibular and palatal side to increase strength
From the distal part of the arch
From a molar hook
Before the maxillary molar, or from the 2nd or 1st PM
From a class III extra oral arch
From a distal hook placed on a palatal plate.
Previously:
A loop on a bow
From a ligature of JARABAK and KAYABASHI
From anterior hooks placed on an inclined plane overbite plate
to help with articulated jumping
Action of class II elastics on continuous arches
The use of Class III elastics has different actions:
Action on the maxillary arch:
Slight maxillary advancement
Advancement with mesial version and extrusion of the 1st
molar
Vestibular version of the upper incisors
Action on the mandibular arch
Distalization of the lower arch
Extrusion of lower incisors
The lower incisors tilt lingually
Pr. AHMED FOUATIH. N 3
Action on the occlusal plane
The Class III relationship is corrected sagittally
The antero-inferior occlusal plane tilts upwards.
Action on the facial pattern
The mandible rotates posteriorly
The chin goes down and back
The lower facial height is increased.
Indications for Class III elastics
-In cases of skeletal patterns of vertical insufficiency
– In vertically normal Class III cases
– In cases of skeletal patterns of vertical excess, treatment must obviously include
surgery.
Finally, the indications for class III elastics concern:
+ Class III dental problems of skeletal patterns
vertical insufficiency
+ Anterior crossbites with incisor end-to-end relationship
centered
+ Retromaxillary with hypo divergence
+ Cases of cl III with incisor overbite facilitating camouflage
by posterior mandibular rotation
+ Mandibular incisor protrusions requiring retraction and
closing of incisal spaces
+ Maximum mandibular anchorage with single-phase extractions
mandibular first premolars
+ Correction of midline deviation
Elastics in orthodontics
Clinical application of Class III elastics
In order to better determine the prognathic patient of class III at risk, do not forget
to use the long-term growth forecast
In cases of vertical insufficiency it is useful:
+ Pro traction of the maxillary arch
+ To tilt the maxillary incisors
+ Use an inclined plane overbite plate with elastics
of class III
+ Use an “M” utility loop to advance the upper arch
+ Use brackets with root-vestibular torque on the incisors
lower to prevent extrusion and lingual version of the force
elastic (to prevent gum dehiscence)
In borderline cases or in vertical excess it is useful
+ Segment the maxillary arch behind the 1st upper molar
+ Keep the rear shims
+ Avoid increasing the vertical direction
+ Use the short cl III anterior closure elastics
+ Check and monitor the ATM
Elastics in orthodontics
Deep cavities may require root canal treatment.
Interdental brushes effectively clean between teeth.
Misaligned teeth can cause chewing problems.
Untreated dental infections can spread to other parts of the body.
Whitening trays are used for gradual results.
Cracked teeth can be repaired with composite resins.
Proper hydration helps maintain a healthy mouth.
Elastics in orthodontics