3 - Classificaiton Of Malocclusion Flashcards
Lecture Aims:
1. How to classify malocclusion in all 3 planes of space: Anterior-Posterior, Vertical, and
Transverse.
2. Learn how to assess the face, teeth, and skeletal pattern clinically and using
radiographs.
What is orthodontics?
- The study of growth of the craniofacial complex, including the maxilla, mandible and cranial vault.
- Development of the occlusion
- The prevention and correction of occlusal anomalies or malocclusion.
Occlusal Terminology:
- Normal Occlusion
- Maloccluion
- Ideal occlusion
Normal Occlusion = Minor deviations from the ideal
Malocclusion = Appreciable deviations from the ideal considered functionally or aesthetically unsatisfactory.
Ideal Occlusion = Andrew’s 6 keys.
Classification of malocclusion
- Classification made of face, teeth and skeletal pattern.
- Relating the maxilla and mandible to the cranial vault. Understanding how the teeth are related to the maxilla, mandible and cranial vault.
Examination
- Examine the face – Skeletal pattern/soft tissues.
- Examine the teeth – Occlusion classified.
- Examine radiographs – Classify the skeletal pattern
Facial Examination:
- The face is first examined in 3 planes of space which gives us a picture of the soft tissues and an idea of the underlying skeletal pattern
- The teeth are then examined both at rest and in function and occlusion needs to be classified
- The radiographs are then examined to classify the skeletal pattern
We confirm our diagnosis with x-rays.
The facial examination needs to be done in 3 planes of space:
Horizontal or Transverse
- Symmetry and chin point
Vertical
- Facial thirds and Frankfort Mandibular- Planes Angle
Sagittal or Profile (Anterior-Posterior relationship)
- Class I, II, III soft tissue profile
Profile assessment - Sagittal or Profile
Profile assessment - how do you carry it out?
Ask the patient to look in the natural head position straight in front of them, like they are looking in the mirror
You are looking to make sure that the face is balanced
The two main points we are looking at are:
- Point A – Deepest concavity just below the nose
- Point B – Deepest concavity in the mandible (just under the lower lip)
Profile assessment - Class I profile
Maxilla and mandible are in reasonable balance with cranial base
Intraorally teeth may not be well aligned but if ideal occlusion there will be perfect alignment
Profile assessment - Class II profile
One patient has reduced lower face height - blonde patient + can get lips together
Other patient has increased vertical dimension
Profile assessment - Class III
Facial examination - Vertical
The Frankfort - mandibular plans angle FMPA used to assess the vertical
Explain
Vertical facial assessment
When assessing the vertical plane, you need to look for balance and harmony in the patients facial thirds:
- Upper third of face
- Middle third of face
- Lower third of face A well balanced face means a patient has equal facial thirds. In orthodontics, we don’t normally look at the upper third of the face, but we focus on how the lower facial third relates to the middle facial third. Clinically we want the proportion between middle and lower thirds to be 50:50
(From glebela to subnasale to soft tissue menton)
Vertical assessment
Describe facial balance
Good facial balance
Vertical assessment
Effects of increased vertical dimension
Vertical assessment
Reduced lower face height
Reduced vertical proportions
What can you see here?
Reduced lower face height and has a deep bite
Deep bite = vertical overlap between upper and lower incisors
Had jaw surgery leading to return of facial harmony between uppper and lower part of face
Explain
Pt has increase in lower face height
Intraorally - anterior open bite = vertical opening in the front, no overlap between upper and lower incisors
After surgery, well balanced and no anterior open bite and has normal overbite
Facial examination - Horizontal or transverse
Class I Incisal relationship
Lower incisors must lie below or at cingulum plateau
Class II Division I Incisal Relationship
The lower incisor edges occlude or pre- occlude posterior to the middle palatal 1/3rd or cingulum plateau of the upper central incisors. The division I aspect comes from the fact that the overjet is increased, and the upper central incisors are usually proclined, although they can be normal
Class II division 2 incisor relationship
The lower incisal edges occlude or pre- occlude posterior to the middle palatal 1/3rd or cingulum plateau of the upper central incisors. The division II aspects comes from the fact that the upper central incisors are retroclined.
Most Class II Div II are on a mild skeletal II base, but there are some patients with an increased overjet, but the upper incisors are still retroclined.
Class III Incisor Relationship –
The lower incisors edges occlude or pre-occlude anterior to the middle palatal 1/3rd or cingulum plateau of the upper central incisors. If the overlap of the upper and lower teeth are normal, then the patient will appear to have normal vertical proportions.
Molar relationship
Angle’s Class I molar relationship
Andrew’s Class I molar relationship
Molar relationship
Class II
Molar relationship
Class III
Canine relationship
Class I
Canine relationship
Class II
This can also be Full unit or half unit class II
In full unit, the upper canine is in the embrasure between the lower canine and lateral incisor
In half unit, the upper canine cusp is in line with the lower canine cusp.
Canine relationship
Class III
Full unit 3 shown below
If occluding cusp to cusp - half unit 3
Radiographic skeletal classification
Lateral Skull Cephalometric Radiograph – The relationship of how the maxilla is related to the mandible and the cranial base. It can be classified as Skeletal Class I, II or III.
The cranial base is marked by the two yellow points on the top of the radiograph: The sella (the middle of the sella turcica) and the nasion (junction of the frontal bone and nasal bone).
With cephalometric radiographs, there is some degree of magnification, so this will affect some of the measurements.
However, we are also interested in angular measurements, and these are not affected by magnification
Standard cephalometric landmarks
Identify below
Cephalometric skeletal classification
Identify 2 commonly used analysis to classify the skeletal pattern and what they are:
Cephalometric skeletal classification
Eastman analysis
What do we measure?
