Textbook for Orthodontic Therapists. Ceri Davies
aesthetics as they are on the labial/buccal surface of teeth.
Any decalcification occurring from treatment will be visible.
Aesthetic brackets can fracture during debonding.
1.8 Lingual Appliances
Lingual appliances (Figure 1.7):
First developed in the 1970s in the USA.
The brackets are bonded onto the palatal/lingual surface of the upper and lower arches.
Lingual appliances use preadjusted ribbonwise brackets, which are thicker vertically than horizontally.
All brackets and archwires are custom made to reduce speech problems and tongue irritation and to help improve finishing.
Custom‐made brackets are good as they can be rebonded directly back on if they debond during treatment; however, if a bracket is lost, new ones have to be specially ordered.
Brackets come in a jig and are all bonded together at once (indirect bonding). It is important to keep the bracket in the jig, because there can be undesired tooth movement if it comes out or is bonded directly to the tooth without a jig.
Lingual appliances can also come in a self‐ligating form.
Advantages:
Good aesthetics.
Decalcification less likely to occur with lingual appliances compared to labial appliances; however, if present it will not be visible.
Upper anterior brackets can act as a bite plane, which is good for treating overbites (flat anterior bite plane or FABP).
Disadvantages:
Can affect patient’s speech.
Much more ulceration can appear.
Discomfort to patient’s tongue.
Clinically demanding on clinicians.
Inter‐bracket span is reduced.
Increased chairside time.
Finishing and detailing are difficult to achieve due to the reduced inter‐bracket span, and archwire bending can be made difficult.
Indirect bonding of brackets or debonding of brackets can result in poor positioning if not bonded back in the correct position.
Increased cost.
Longer treatment time.
Figure 1.7 Typhodont showing Harmony lingual appliance.
2 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