Class II Minimum-Touch Approach in an Evolving Orthodontic World Luis Carriere
Objectives of class 2 mixed dentition
· Mandible moved forwards
· Decrease the projection of the maxilla – to shorten and curl the upper lip
· Improve structures of TMJ
Carriere appliance
· Rigid appliance on 3-6
· Rubber bands
· Change the occlusal plane to maximise projection of mandible
· Joint on 6 to rotate the molar
· Lower arch – VFR with bracket on L6
· Class 2 elastic from U3-L6
Advantage
· Segmentation of arch
o Freedom of the arch to move for AP correction
§ Independent RHS and LHS, can overcorrect
· Patient comfort high compared to Forsus appliance
· Self limiting for molar rotation correction
o Deliver rotation necessary, not any greater as self collision points built into the appliance
o 87% of class 2 molars require rotation Henry 1956
o Molar rotation: if upper molars rotate mesially = more class 2, distal rotation class 2Arnald 1954
Mixed dentition challenges
· Occlusal cusps shallow = poor intercuspation
o Solution = overcorrection to allow for AP relapse
Changes with Carriere appliance
· Upper lip length reduces – as the protrusive upper incisors elongate the upper lip
o Upper lip curls and shortens
· Improve Wits appraisal Kim-Berman – 2019
· Clockwise rotation occlusal plane
o Sounds contradictory
§ However in class 2 condyle is posteriorly seated Gokalp 2016 and the disc is anterior, Carriere appliance allows distraction of the condyle – releasing the space at the condyle, therefore the disc repositions anteriorly
§ Airway improvement – further studies required
§ Preserve maxillary volume – posterior dental repositioning, no archlength reduction
Adult patient
· Severe class 2 + TMD
· Orthognathic surgery is an option however there will be no correction of the TMD
o Condyle is distal in position and impinging on the retro-discal ligaments
· If condyle moves forwards
o Elastic recovery of TMJ ligaments aids distraction and permanent repositioning of the mandible anteriorly
o TMD resolved as posterior disc no longer impinged and reposition of mandible anteriorly, no change in growth
· Limited evidence on Carriere appliance resulting in condylar changes
