NEET MDS Shorts
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OrthodonticsSOLUTION
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OrthodonticsAngle Class III Malocclusion:
Angle Classification:
The Angle classification system, developed by Edward Angle, is a
widely used method for categorizing malocclusions based on the
relationship of the first molars and the canines.
Class III Malocclusion:
In Angle Class III malocclusion, the lower first molar is positioned
more mesially (toward the midline) relative to the upper first molar.
This means that when the first molars are in occlusion, the lower first
molar is ahead of the upper first molar.
Clinical Implications:
Class III malocclusion is often associated with a prognathic
mandible (where the lower jaw is positioned forward) or a retruded
maxilla (where the upper jaw is positioned backward). This can lead to
various functional and aesthetic concerns, including difficulties with
biting and chewing, as well as facial profile changes.
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Orthodontics
The primary purpose of Howe's Analysis is to assess the width of the
dental arches and to identify any discrepancies between the maxillary
(upper) and mandibular (lower) arches. This is particularly important in
cases of malocclusion, where the alignment of the teeth and the relationship
between the jaws may be compromised.
The analysis involves measuring specific distances on the dental casts,
including:
Intercanine Width: The distance between the cusp
tips of the canines.
Interpremolar Width: The distance between the cusp
tips of the first premolars.
Intermolar Width: The distance between the cusp
tips of the first molars.
These measurements are used to calculate the Percentage of
Maxillary Buccal Arch Width (PMBAW%), which is a key indicator in
the analysis.
The results of Howe's Analysis can indicate different treatment needs:
Normal Case: A PMBAW% within a certain range
(typically around 50-60%).
Narrow Case: A PMBAW% below the normal range,
indicating a need for arch expansion.
Wide Case: A PMBAW% above the normal range, which
may suggest the need for extraction or other interventions.
Borderline Case: A PMBAW% around 44, indicating
that the arch width is at a threshold where careful consideration is
needed for treatment options.
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OrthodonticsExplanation: Thumb sucking is a common behavior in children and does not always lead to maxillary prognathism, psychological disturbances, or the need for appliance therapy. Many children stop thumb sucking on their own without intervention.
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OrthodonticsSolution
Circumferential supracrestal fibrotomy (CSF) eliminates the pull of the stretched supracrestal gingival fibres which are the major cause of orthodontic relapse.
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OrthodonticsReverse labial bow is so called as activation of the bow is done by opening the U-loop, instead of compressing as is seen in the conventional labial bows.
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OrthodonticsSOLUTION
Angle of Convexity The angle of convexity is formed by the intersection of line from N to point A, to point A to pogonion.
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OrthodonticsSOLUTION
The reason is found in the concept of "dental compensation for skeletal discrepancy. This can occur naturally as well as being created by orthodontic camouflage treatment.
In mandibular prognathism, for instance, as the individual grows the upper incisors tend to protrude while the lower incisors incline lingually.
By the time growth is completed, the dental discrepancy usually is smaller than the jaw discrepancy.
Tooth position has compensated at least partially for the jaw discrepancy.