Ortho Class III Treatment Flashcards
What is the definition of a class III malocclusion?
When the lower incisor is positioned anterior to the cingulum of the upper incisor.
The overjet is reduced or reversed.
How does a class III incisor relationship influence the anteriorposterior skeletal features of class III?
Patient usually present with a class III skeletal base.
But they can also have class I skeletal base (class II skeletal base is very rare)
How does having a class III incisive relationship affect the transverse skeletal relationship?
The retrusive maxilla sits on the wider part of the mandible causing a bilateral crossbite.
List the dental features of a class III malocclusion?
Sometimes class III molar relationship
Tendency to reverse overjet
Reduced overbite
Proclined UI. Retroclined LI
Crossbite- can be anterior or buccal.
Maxilla often crowded and mandible often aligned or spaced.
Tendency for displacement on closing.
What causes the malaignment of teeth in a patient with class III?
The teeth will still erupt towards each other despite the underlying skeletal discrepancy.
How do we estimate the treatment difficulty in class III malocclusions?
Greater the teeth in anterior crossbite.
If there is a skeletal element in aetiology
Greater the AP discrepancy
Presence of an anterior open bite.
What are the dental health reasons for treating class III incisors?
Attrition
Gingival recession- the upper incisors heavily occluding down on the labial of the lower incisors.
Mandibular displacement- to achieve occlusion by causing wear on the labial face of the upper central and lower incisors.
When would we accept and monitor class III incisor relationships?
Mild cases
No dental health indications (Displacement/ attritions)
No patient concerns
When would we treat class III incisor relationship with URA interceptive treatment.
& How.
For these situations when the patient is in mixed dentition-
Class III incisor relationship due to early contact of permanent incisors (mandibular displacement)
Anterior crossbite
Lateral incisor crossbite (only if the 3s are high above the 2s)
This can be treated by proclining the incisors over the bite using an URA
How can we treat a class III incisor relationship with growth modification?
Using:
Reverse twin bock
Protracton headgear
Bollard implants.
What is protraction headgear?
A device that pulls the maxilla forward using anchorage on the forehead
But there are difficulties with compliance as it needs to be worn by an 8-10 year old 14 hours a day
What are bollard implants?
A type of temporary anchorage device used for growth modification used in late mixed and permanent dentition
A bone plate is inserted into the bone of the zygomatic crest or lower canine region by mucoperisoteal flap.
Used to treat Class iii
When would we use orthodontic camoflauge for treatment of a class III incisor relationship?
Once growth has stoppped.
In patients with mild to moderate class III skeletal base (where ANB <0*)
Average or increased overbite
Pt has the ability to achieve an edge to edge incisor relationship.
Pt has little or no dentoalveolar compensation (we need space to retrocline/ procline the teeth)
When would orthognathic surgery be used for treatment of a class III incisor relationship?
When the patient has aesthetic or functional concerns.
What treatment does a patient undergoing orthognathic surgery need to undergo?
Pre-orthodontic treatment to align teeth and decompensate. (upper incisor at 109 degrees and lower incisor at 90 degrees.
Orthognathic surgery
Post surgical orthodontics-
