2 - Orthodontic assessment Flashcards
At what age should initial orthodontic assessment occur?
9 years
At what age should a comprehensive orthodontic assessment occur?
11-12 years
Define malocclusion.
Significant deviations from the ideal, which can be considered unsatisfactory aesthetically or functionally and may require treatment
What MH can contra-indicate orthodontics?
- allergy (Ni or latex, although allergy in the mouth is less common)
- removable appliances are not suitable for epileptics
- those undergoing MRI scans cannot have fixed appliances
What DH can contra-indicate orthodontics?
- trauma to the permanent dentition (root resorption)
- infrequent attender
- poor OH
What habits can contribute to teeth becoming proclined?
- thumb/digit sucking
- lower lip sucking
- tongue thrust
- chewing finger nails (can cause root resorption of 1s)
What is tongue thrust?
- all babies do this when edentulous to create seal when swallowing
- usually stops when teeth come in
- can cause teeth to become proclined and any treatment will likely relapse
What planes do you examine the patient in?
- antero-posterior
- vertical
- transverse
How do you assess AP clinically?
- visual
- palpate skeletal bases (index and middle finger)
What is soft tissue point A?
Inner most curvature of upper lip (basal bone)
What is soft tissue point B?
Inner most curvature of lower lip
Describe a class I skeletal relationship.
Maxilla 2-3mm in front of mandible
Describe a class II skeletal relationship.
Maxilla more than 3mm in front of mandible
Describe a class III skeletal relationship.
Maxilla <2mm in front of mandible or maxilla behind mandible
How do you assess the vertical plane clinically?
- Frankfort-Mandibular planes angle (FMPA)
- the angle created by the Frankfort plane and lower border of mandible
- lines should meet at the back of the head
What is the consequence of an increased FMPA?
Anterior open bite
What is the consequence of an decreased FMPA?
Deep bite
How do you assess the transverse plane clinically?
- look at patient straight on and have them looking down
- check that the centre of the face aligns with the centre of the mandible (ignore nose)
Describe competent lips.
- lips meet at rest
- relaxed mentalis muscle
Describe incompetent lips.
- lips do not meet at rest
- relaxed mentalis muscle
Describe lip trap.
- lower lip trapped by upper incisors
- may procline upper incisors
- may lead to relapse of overjet if persists at the end of treatment
Describe a strap lower lip.
- hyper active lower lip may retrocline lower incisors
- indicates likely instability at the end of treatment
What are the occlusal effects of thumb/digit sucking?
- unilateral posterior crossbite
- vertical height can be incorrect
- reduced or incomplete overbite, localised AOB
- narrow upper arch
- proclination of upper anterior, retroclination of lower anteriors
What should be assessed intra-orally during an orthodontic assessment?
- OH/perio
- teeth present
- any teeth of poor prognosis
- crowding/spacing/rotated teeth
- inclination/angulation
- palpate for canines if not present
- any teeth of unusual morphology
What is the correct angulation of the upper incisors?
110 degrees from the Frankfort plane
Describe a class I incisor relationship.
Lower incisors occlude with the cingulum plateau of the upper central incisors
Describe a class II div 1 incisor relationship.
The lower incisors lie posterior to cingulum plateau of upper incisors, the upper incisors are proclined and there is an increase in overjet
Describe a class II div 2 incisor relationship.
The lower incisors lie posterior to cingulum plateau of upper incisors, the upper incisors are retroclined, so the overjet is usually reduced
Describe a class III incisor relationship.
The lower incisors edges lie anterior to the cingulum plateau of the upper incisors, the overjet is reduced or likely reversed
