Patient Assessment
Patient assessment is very important prior to orthodontic treatment. Including radiographs and study models, each patient should have an orthodontic assessment. This assessment looks at the patient's skeletal features and malocclusion. Assessment must be done to help the orthodontist assess the need for treatment and create a treatment plan that is appropriate to the patient.
A patient assessment is done in two ways:
Extra‐oral assessment
Intra‐oral assessment.
The three planes of space are used when carrying out the assessments. The extra‐oral assessment refers to outside the mouth, whereas the intra‐oral looks inside the mouth. The two assessments consider the following:
Extra‐oral assessment: assesses the facial profile.
Intra‐oral assessment: assesses the position of the upper and lower dentition.
2.1 The Three Planes of Space
The three planes of space we refer to in orthodontics are:
Antero‐posterior plane (AP): assesses the patient front to back.
Vertical plane: assesses the patient up and down.
Transverse (horizontal) plane: assesses the patient side to side.
2.2 Extra‐Oral Assessment
There are four stages to carrying out an extra‐oral assessment. The first three look at the three planes of space, whereas the fourth stage concentrates on the lower third of the face.
2.2.1 Antero‐posterior Plane
The patient is viewed from the side.
This stage looks at the patient's skeletal pattern in the AP plane (front to back).
It assesses the patient’s profile and the relationship of the maxilla, referred to as the A point, and the mandible, referred to as the B point.
Patients are assessed by the following:Skeletal class I: Mandible is 2–3 mm posterior to the maxilla (Figure 2.1).Skeletal class II: Mandible is retruded relative to the maxilla (Figure 2.2).Skeletal class III: Mandible is protruded relative to the maxilla (Figure 2.3).
2.2.2 Vertical Plane
The patient is viewed from the front and side.
This stage looks at the patient’s skeletal pattern in the vertical plane (up and down).
It assesses the lower part of the face, looking at the LAFH (lower anterior facial height) and FMPA (Frankfort‐mandibular plane angle).
LAFH:
LAFH should measure the same as UAFH (upper anterior facial height).Figure 2.1 Skeletal class I.Figure 2.2 Skeletal class II.Figure 2.3 Skeletal class III.
UAFH is measured from the eyebrow to the base of nose (Figure 2.4).
LAFH is measured from the base of the nose to the lowest point on the chin.
FMPA:
This is the angle where the Frankfort plane and mandibular plane meet (Figure 2.5).
This is assessed by placing one hand on the Frankfort plane and one hand on the mandibular plane and assessing where they cross by eye.
The measurements indicate the following:
Average LAFH and FMPA – usually seen in class I.
Decreased LAFH and low FMPA – usually seen in class II.
Increased LAFH and high FMPA – usually seen in class III.
Figure 2.4 Vertical plane measurements: frontal view.
2.2.3 Transverse Plane
The patient is viewed from the front and looking down on the face from above.
This stage looks at the patient’s skeletal pattern in the transverse plane (side to side).
This is assessed by looking at the patient’s face and recording any significant asymmetry (Figure 2.6) – all patients are asymmetrical.Figure 2.5 Vertical plane measurements: right profile.Figure 2.6 Transverse plane: frontal view looking for any asymmetry.
To assess whether the occlusal plane follows the line of asymmetry, a tongue spatula is used and the patient is asked to bite onto this (Figure 2.7). In patients who have a significant asymmetry, this will be noticeable by the tongue spatula not lying flat.
Figure 2.7 Transverse plane: frontal view looking for any asymmetry with a spatula.
2.2.4 Profile Pattern
This is assessed by looking at the LAFH.
Patients can present with different profiles: concave, straight, or convex (Figure 2.8).
In the convex profile
