Orthodontic assessment Flashcards
What do we look for when we do our extra oral examination from an orthodontic point of view
- Assess hard and soft tissues in 3 planes
- View patients head from front side above and below
- TMJ
Name the 3 planes we assess the hard and soft tissues in
- Antero-posterior
- Vertical
- Transverse
How do we assess the anterior poster plane
- Assess in natural head position
- Can use the kettle method or just visually assess
What is the kettle method
Using your index finger and pointing finger palpate pateitns upper and lower jaw and determine if you fingers are pointing straight (class I), Upwards (Class III), downwards (Class II)
What is an alternative to the KETTLE METHOD
zero meridian line (True vertical line)
How do we determine where the zero meridian line is
- Get patient to look forward
- Drop an imaginary line vertical form the top of the nose
- Assess the relationship of the lower lip and chin to this line
Describe what you might see in a class I skeletal base in relation to the zero meridian line
- A balanced profile
- The upper lip rests on or ahead of the zero meridian line
- Chin lies slightly behind the zero meridian line
- Mandible likes 2-4mm behind the maxilla
Describe what you would see in a class II skeletal base in relation to the zero meridian line
- Mandible appears further behind the maxilla
- Chin lies behind the zero meridian line
- Retrusive mandible
Describe a patient with class iII skeletal base in relation to the zero meridian line
- Mandible lies ahead of the maxilla
- Chin lies ahead of zero meridian line
- Upper lip may be close to or behind the zero meridian line
- Protrusive mandible and/or recursive maxilla
What do we look for if we suspect a retrusive maxilla
- Paranasal hollowing
- Flat infra orbital margins
- Flat zygoma
- In severe cases sclera may be visible below the iris
How can we assess the vertical plane of a patient
- Rule of equal thirds
- Frankfort mandibular planes angle (FMPA)
- Centrelines
What is the rule of equal thirds
Approx equal thirds between:
- Hairline (trichion) to between the eyebrows (Glabella)
- Glabella to base of nose (subnasale)
- Subnasale to bottom of chin (menton)
Where does Frankforts plane run
From the bony infra orbital margin to external auditory meatus
Where does the mandibular plane run
Along the border of the mandible
What is an average Frankfurt mandibular plane angle
Where they meet at the occiput
(before occiput= increased, after occiput= decreased)
How do we assess the transverse plane in a patient
- Assess from above below and in front
- Compare between bilateral structures
- Compare to facial midline
What do we look at when examining the lips
- Are they competent
- Length
- Naso labial angle
- Relationship of lower lip to upper incisors
- Relationship of upper lip to upper incisors
- Smile aesthetics
- Tone / fullness
What is the average value of the naso labial angle
90-110 degrees
How much of the upper incisors is seen at rest
3mm on average but this reduces with age
What is a lower lip trap
When the lower lip function behind the upper incisors
In whom is a lower lip trap more common
Patients with class II div I malocclusion
Why is a lower lip trap a concern
As the activity of the lower lip prolines the upper icons further increasing the patients overjet
What is a high lower lip line
Where the lower lip covers the upper central incurs and retroclines them
What can a high lower lip line lead to
Class II div 2 malocclusion
