Join me as I summaries Kleber’s lecture on the use of intermaxillary elastics in orthodontics, topics of force magnitude, side effects and how to counter them, use of a sliding jig and stability are described.

Force magnitude more important than the size of the elastics

· Large variation forces used by orthodontists in Kurol 1996

· Use a gauge on every patient

· Excessive = damage to PDL and RR

· Force required

o Retraction of upper incisors = 250g each side Oesterle 2012 / 350 g Proffit

o Individual

Class 2 elastics effects

· Distalise anterior teeth

· Mesial of lower posterior teeth

· Extrusion of upper anterior teeth

· Extrusion of lower posterior teeth

· Rotate occlusal plane clockwise

· Retrusive upper lip

· Protrusive lower lip

How to avoid side effects

· Case selection: avoid high angle cases

· Avoid upper arch retraction on round wire

· Reduce vertical vector

o Increase horizontal distance mesial of U2s and L7s

o Change the vertical vector by using a sliding jig

§ Sliding jig moves vector from above the brackets upper, to below the bracket, lower arch force from below the bracket to above the bracket

§ Sliding jig – directs upper arch forces to the molars – more efficient than to archwire only or canine

Class 2 subdivision

· Class 2 one side, class 1 other side.

· Of dental origin, no skeletal

· Usually cant on class 2 side, with arch up on the RHS

· Class 2 elastic on effected side

· Distalisation on URQ with sliding jig

· Retraction of the arch – on rectangular SS – 350g

Torque

· Can be lost upper incisors

· Place torque into the archwire during the retraction – not after retraction

Finishing

· Triangular elastics

Class 2 elastic stability

· Patient may posture: assess displaced mandible / CR

· Tooth movement:

o Bony formation may not be complete

o PDL may not be reorganised

§ REQUIRE 3 months of wear for stability, bone growth and PDL