Lab 2.1 Classification of Malocclusion Flashcards
When the teeth in the mandibular arch come into contact with those in the maxillary arch in any functional relation, are said to be in __________?
Occlusion
A condition in which there is a deflection from the normal relation of the teeth to other teeth in the same arch and/or to teeth in the opposing arch.
Malocclusion
Classifications of malocclusion can be divided into two types, which are?
a) Quantitative and Qualitative
b) Intra-arch and Inter-arch
This classification is based on the relationship of the mesiobuccal cusp of the maxillary first molar and the buccal groove of the mandibular first molar
Angle’s classification of malocclusion
The mesiobuccal cusp of the upper first permanent molar occludes with the mesiobuccal groove of the lower first molar, but line of occlusion is incorrect because of malposed teeth, rotations or other discrepancies.
Class I malocclusion
The mesiobuccal cusp of the lower first permanent molar occludes distal to the class I position.
Class II malocclusion
- Condition when class II molar relationship is present with proclined upper central incisors.
- There is an increase in overjet.
Class II Div 1
- Condition when class II molar relationship is present with retroclined upper central incisors, upper lateral incisors may be proclined or normally inclined.
- Overjet is usually minimal or may be increased.
Class II Div 2
Condition when the class II molar relationship exists on only one side with normal molar relationship on the other side.
Class II Subdivision
The mesiobuccal cusp of the lower first molar occludes mesial to the class I position.
Class III malocclusion
Due to occlusal prematurity, when the mandible moves from rest position to occlusion, it slides forward.
Pseudo Class III malocclusion
It’s also known as postural class III.
Pseudo Class III malocclusion
Condition in which class III molar relationship is present only on one side with normal relation on the other side.
Class III Sub-division
What are the 2 modifications of Angle’s Classifications?
- Lischer’s modification
- Dewey’s modification
He introduced following names to the Angle’s classification:
* Neutrocclusion
* Distocclusion
* Mesiocclusion
Benno Lischer
Neutrocclusion
Class I
Distocclusion
Class II
Mesiocclusion
Class III
He divided Angle’s class I & III into further types.
Martin Dewey
Identify the Class and Type:
- Crowded maxillary anterior teeth. Canines may be abnormally positioned.
Class I Type 1
Identify the Class and Type:
- Proclined or labioversion of maxillary incisors.
Class I Type 2
Identify the Class and Type:
- Anterior cross bite present.
Class I Type 3
Identify the Class and Type:
- Posterior cross bite present.
Class I Type 4
Identify the Class and Type:
- Mesioversion of molars.
Class I Type 5
Identify the Class and Type:
- Well aligned teeth & dental arches. Edge-edge relationship.
Class III Type 1
Identify the Class and Type:
- Crowded mandibular incisors.
Class III Type 2
Identify the Class and Type:
- Crowded maxillary incisors, underdeveloped maxilla. Anterior cross bite present.
Class III Type 3
What are Andrew’s 6 Keys to Normal Occlusion?
- Correct molar relationship (Class I).
- Correct crown angulations.
- Correct crown inclination
- No rotation present.
- Teeth in tight contact with no spacing.
- Occlusal plane / curve of spee should be flat. (i.e. it should not be deeper than 1.5mm; flat to slight curve).
Bannet & McLanghlan’s additional classification to Andrew’s 6 keys.
No tooth size discrepancies.
This classification considered relationship between maxilla & mandible, in anteroposterior direction.
Skeletal classification
Maxilla & mandible are in harmony with each other.
Class I (skeletal classification)
- Maxilla lies ahead of mandible with reference to anterior cranial base.
- Maxilla is PROGNATHED.
Class II (skeletal classification)
- Maxilla lies posterior to mandible with reference to anterior cranial base.
- Maxilla is RETROGNATHED.
Class III (skeletal classification)
- Based upon incisor relationship, proposed in 1983.
- Do not consider molar relationship in some cases.
British Standard Classification of Incisor Relationship
The lower incisor edges occlude with or lie immediately below the cingulum plateau of upper central incisors
Class I (British Standard Classification)
The lower incisor edges lie posterior to the cingulum plateau of the upper incisors.
Class II (British Standard Classification)
The lower incisor edges lies anterior to the cingulum plateau of the upper incisors. The overjet is reduced or reversed.
Class III (British Standard Classification)
Identify what class and division:
- The upper central incisors are proclined or of average inclination & there is an increase in overjet.
Class II Div 1
Identify what class and division:
- The upper central incisors are retroclined. The overjet is usually minimal or may be increased
Class II Div 2
When the mesial slope of upper canine coincides with the distal slope of lower canine.
Class I (Canine classification)
(Additional info)
What’s the hierarchy in choosing what classification to use?
- Angle’s classification (molars)
- Canine classification
- British classification (incisors)
From most accurate to least.
When the mesial slope of upper canine is ahead of the distal slope of lower canine
Class II (Canine classification)
When the mesial slope of the upper canine lies behind the distal slope of the lower canine.
Class III (Canine classification)
In this classification system, the dental arches are related to three anthropologic planes.
Simon’s classification
What are the 3 anthropologic planes used in Simon’s classification?
- Franfort horizontal (eye-ear plane)
- Orbital plane
- Raphe median / mid-sagittal plane
This plane helps detect deviations in the vertical plane.
Frankfort horizontal plane
Frankfort horizontal plane:
- Dental arch closer to the plane is called _________ and farther away is called _________.
Attraction = closer
Abstraction = farther
This plane helps detect deviations in the transverse plane.
Orbital plane
Orbital plane:
- Dental arch more anteriorly placed is called _________ and posteriorly placed dental arch is called ________.
Protraction = anterior
Retraction = posterior
This plane helps detect deviations in the sagittal plane.
Midsagittal plane
Mid-sagittal plane:
Dental arch closer to midsaggital plane is called _________ and farther away is called ________-.
Contraction = closer
Distraction = away
It was proposed to overcome the drawbacks of Angle’s classification.
Ackerman & Proffit’s Classification
This system includes Angle’s classification & five characteristics of malocclusion within a Venn diagram.
Ackerman & Proffit’s Classification
5 major characteristics in Ackerman & Proffit’s Classification?
- Dentofacial appearance
- Teeth/arch form
- Transverse (wide/narrow)
- Sagittal (A-P; class II/III)
- Vertical (deep/open bite)
What are the 2 addition to the 5-characteristics classification system?
- Esthetic line of occlusion
- Rotational axes
- In modern analysis, another curved line characterizing the appearance of the dentition is important.
- This follows the facial edges of the maxillary anterior and posterior teeth.
Esthetic line of occlusion
- In addition to relationship in the transverse, anteroposterior and vertical planes of space used in traditional 3-D analysis, rotations around axes perpendicular to three planes also must be evaluated.
- It’s a useful way to evaluate the relationship of the teeth to the soft tissues that frame their display.
Rotation axes
What are the 3 rotational axes?
- Pitch
- Roll
- Yaw
- The vertical relationship of the teeth to the lips & cheeks can be conventionally described as up-down deviations around the anteroposterior axes.
- Evaluated clinically & from cephalometric radiographs.
Pitch
- Describes the vertical position of the teeth when this is different on the right & left sides.
- Viewed as up-down deviations around the transverse axes.
- It’s seen with lips relaxed and more clearly on smile, in both frontal and oblique view
Roll
- Rotation of the jaw or dentition to one side or the other, around a vertical axes, produces a skeletal or dental midline discrepancy.
- Viewed as left-right deviations around the vertical axes.
Yaw
Familiarize!
VALIDITY OF ACKERMAN & PROFFIT CLASSIFICATION:
Merits
– Explained complexities of malocclusion.
– All three-dimensional problems included.
– Differentiation between skeletal & dental problems are made.
– Profile of the patient is given.
– Arch length problems are evaluated.
– Helps in complete diagnosis & treatment planning.
De-merits
– Etiological considerations not included.
– Based on static occlusion only.
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- Rotation of the jaw or dentition to one side or the other, around a vertical axes, produces a skeletal or dental midline discrepancy.
- Viewed as left-right deviations around the vertical axes.
Yaw
Transverse + Sagittal = (what kind of rotation axis)?
Yaw
Transverse + Vertical = (what kind of rotation axis)?
Roll
Vertical + Sagittal = (what kind of rotation axis)?
Pitch