The Increased Y-Axis Angle In Downs
Write short note on Y-axis.
Answer. The angle is obtained by joining the FH plane with sellagnathion line.
Y-axis is of the two types, i.e. Down’s Y-axis and Rakosi’s Y-axis.
“Understanding the role of the Y-axis angle in orthodontic diagnosis”
Down’s Y-axis
- Down’s Y-axis is also known as growth axis.
- Y-axis forms an integral part of assessment of skeletal pattern in Down’s analysis.
- Y-axis indicates growth pattern of individual.
- Cephalometric plane used in Y-axis is Frankfort horizontal plane.
- Cephalometric landmarks used are sella, gnathion, porion and orbitale.
- Mean value is 59.4° and it ranges from 53° to 66°.
“Importance of studying increased Y-axis angle for better orthodontic outcomes”
Interpretation
- Increment in Y-axis is indicative of vertical growth pattern.
- Decrease in Y-axis is indicative of horizontal growth pattern.
- It indicates the position of chin in anteroposterior and vertical plane.
- Y-axis indicates the downward, rearward and forward position of chin.
“Common challenges in addressing an increased Y-axis angle effectively”
Rakosi’s Y-axis
- It is the measured angle between nasion, sella and gnathion.
- It determines the position of mandible in relation to cranial base.
- Its mean value is 66°
- If angle is greater than 66° it implies retrognathic mandible with vertical growth pattern.
- If angle is lesser than 66° it implies prognathic mandible with horizontal growth pattern.
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