lec 3 - classification of malocclusion Flashcards
Description of dentofacial deviations according to a common characteristic or norm.
CLASSIFICATION OF MALOCCLUSION
o Frequently referred to during communications between consultants;
o Certain identities within a subgroup will require same treatment protocols.
CLASSIFICATION OF MALOCCLUSION
Malocclusion may involve 4 tissue systems:
1) Teeth
2) Bones
3) Muscles
4) Nerves
In some cases ___________ are irregular, jaw relationship may be good and muscle + nerve function normal.
only teeth
In other cases, teeth may be regular in their alignment but_________________ may exist, so that teeth do not meet properly during function.
abnormal jaw relationship
Another case, maloccclusion may involve all 4 systems, with:
o Individual tooth malpositions
o Abnormal jaw (or bone) relationship
o Abnormal nerve
o Muscle function
Malocclusion Groups (3)
(1) Dental Dysplasias
(2) Skeletodental Dysplasias
(3) Skeletal Dysplasia
- When individual teeth within one or both jaws are abnormally related to each other.
- Only tooth system is involved.
- May involve a couple of teeth or may involve majority of teeth present.
- Relationship of upper + lower jaw is considered normal.
- Facial balance is almost always good.
- Muscular function is also considered normal.
DENTAL DYSPLASIAS
- In dental or dento-alveolar dysplasias, there is usually __________ to accommodate all teeth may be due to local factors:
o _________ of deciduous teeth
o ____________ of deciduous teeth
o Improper ___________
o But it is more likely due to ________________.
o __________discrepancy
lack of space
Premature loss
Prolonged retention
restorations
basic hereditary pattern
Tooth size
- In dental or dento-alveolar dysplasias, _____________________ + conformation of teeth to arch form dictated by configuration of upper + lower jaws is imperfect.
o _______ may be rotated.
o ________ may have insufficient room to erupt into their normal place in dental arch.
o _________ may be partially impacted or may be erupting bucally or lingually to normal positions in dental arches.
o _______ segments may have drifted mesially.
Forcing teeth anterior to them into positions of malocclusion.
inclined plane relationship
Incisors
Canines
Premolars
Molar
(4): May be good although there is a disharmonious relationship between teeth, supporting bone, resulting in individual tooth irregularities.
- Facial development
- Skeletal pattern
- Muscle development
- Function supporting bone
- Time is long past when the dentist thought of orthodontic problems as involving only the teeth.
- It is now recognized that the anteroposterior relationship of maxilla + mandible to each other and to cranial base is of vital concern.
- Individual tooth irregularities may or may not be present in this particular category but the relationship of maxilla to mandible and of both the maxilla + mandible to cranium have profound influence on orthodontic objectives.
SKELETAL DYSPLASIAS
- Frequently: (3) are involved with adaptive or compensatory muscle activity to fit skeletal dysplasia.
- Relatively few malocclusions are skeletal involvements exclusively.
o Bone system
o Neuromuscular system
o Tooth system
- It describes malocclusions where not only are the teeth, singly or in groups, in malposition, but where there is an abnormal relationship of maxilla + mandible to each other or to cranial base.
- In addition to irregularly positioned teeth, mandible may be too far forward or backward with respect to either or both cranial base + mandible.
- Skeletodysplasias are more involved.
- Require a different therapeutic approach than dental dysplasias.
- Muscle function is not normal in this group.
- All four tissue systems are involved.
- Depends on type + degree of skeletal malrelationship
- In orthodontic practice, this group makes up largest percentage of patients.
SKELETODENTAL DYSPLASIAS
- In 1899, Edward Angle classified malocclusion based on:
o _____________ of teeth, dental arches + jaws
o Considered _________________ as a fixed anatomical point in jaws + key to occlusion.
o Based his classification on relationship of this tooth to other teeth in _____________.
Mesial-distal relation
maxillary 1st permanent molar
mandibular jaw
- It is simple.
- Easy to use.
- Conveys precisely what it was conceived for:
o Relationship of ________________ with respect to _______________ - Classified malocclusion into 3 broad categories
o Designate as “_______”
o Represented by Roman numerals – I, II, III
mandibular teeth
maxillary 1st permanent molar
Classes
- Mandibular dental arch is in normal mesiodistal relation to maxillary arch.
CLASS I – MALOCCLUSION
- Mesiobuccal cusp of maxillary 1st permanent molar occludes in the buccal groove of mandibular 1st permanent molar.
CLASS I – MALOCCLUSION
- Mesiolingual cusp of maxillary 1st permanent molar occludes with occlusal fossa of mandibular 1st permanent molar.
CLASS I – MALOCCLUSION
- Occasionally, mesiodistal relationship of upper + lower 1st molars may be normal.
- Interdigitation of buccal segments correct.
- With no overt tooth malpositions.
- But entire dentition is forward on their respective bases.
Class I – Bimaxillary Protrusion
- A malocclusion may exist in the presence of abnormal perioral muscle function.
- With a normal mesiodistal 1st molar relationship.
- But with the teeth anterior to 1st molars completely out of contact during full habitual occlusion.
Class I – Open Bite
- Mandibular dental arch + body are in distal relation to maxillary arch.
CLASS II – MALOCCLUSION
- When jaws are at rest + teeth approximated in centric occlusion
CLASS I – MALOCCLUSION
- By interference, supporting maxillary + mandibula bony bases are in normal relationship.
CLASS I – MALOCCLUSION
- Malocclusion is essentially a dental dysplasia.
CLASS I – MALOCCLUSION
