Down’s Analysis

Down’s Analysis

• It is the measurement of slope of occlusal plane to Frankfort horizontal plane.
• Occlusal plane is formed by drawing a line bisecting overlapping cusps of first molars and overbite of incisors.
• Cant of occlusal plane is gained by measuring angle between occlusal plane and Frankfort horizontal plane.
• Mean value is 9.3°

“Understanding the role of Down’s analysis in cephalometric evaluation”

• Decrease in the value occurs in the cases of long ramus while it is increased in cases of short ramus.

• It is formed by long axis of maxillary and mandibular incisor.
• Mean value is 135.4°.
• Interincisal angle is less in people whose incisors are tipped forward.

“Common challenges in using Down’s analysis effectively”

• It is formed where the occlusal plane and long axis of mandibular incisor meets at an intersection.
• Its mean value is +14.5°.
• At the point of intersection inside the angle can be positive or negative based on deviation from right angle.
• Its value is increased in proclined mandibular incisors and decreased in retroclined mandibular incisors.

• It is formed where the mandibular plane and long axis of mandibular incisor meets at an intersection.
• Its mean value is +1.40.
• At the point of intersection inside, the angle can be positive or negative based on deviation from right angle.
• Its value is increased in proclined mandibular incisors and decreased in retroclined mandibular incisors.

“Role of angular measurements in Down’s analysis”

• It is gained by drawing a line from point A to pogonion and calculating the distance between incisal edge of maxillary central incisor to A-pog line.
• Mean value is + 2.7 mm.
• When incisal edge lies ahead of A-Pog line the value is positive.
• Increase in value is suggestive of protruded maxillary incisors while decrease in value is suggestive on retruded maxillary incisors.

“Asymptomatic vs symptomatic effects of misinterpreted Down’s analysis data”