Cephalometric analysis
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Transcript of Cephalometric analysis
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Qassim University-College of DentisrtyOrthodontic Department
Cephalometric Analysis
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1. Skeletal relationships :A. Sagittal basal relationships ( anterior-posterior ).B. Vertical basal relationships.
2. Dentoalveolar relationships.3. Soft tissues analysis.
The cephalometric analysis can be divided into three parts:
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A.Sagittal basal relationships ( anterior-posterior ):
1. SNA.2. SNB.3. ANB.4. Wits appraisal.5. Angle of convexity (NAPog).6. Cranial base angle (NSBa, Saddle angle).
B. Vertical basal relationships:1. SN-Mxpl. 2. SN-Mnpl.3. MMpA.4. Gonial angle (Angle of the mandible, Condylar angle).5. Facial Proportion (FP).
1. Skeletal Analysis:
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A. Sagittal basal relationships ( anterior-posterior ):1. SNA.2. SNB.3. ANB.4. Wits appraisal.5. Angle of convexity (NAPog).6. Cranial base angle (NSBa, Saddle angle).
1. Skeletal Analysis:
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1. SNA.
• Measured the junction of SN line and NA line. • It evaluates the antero-posterior position of the
maxilla in relation to the anterior cranial base.• The normal average is 81±3 (normal or orthognathic
maxilla). • above the normal range it would be prognathic
maxilla. • and when it is below the normal range it would be
retrognathic maxilla.
A. Sagittal basal relationships ( anterior-posterior ).
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2. SNB.
• Measured the junction of SN line and NB line.• It evaluates the antero-posterior position of the
mandible in relation to the anterior cranial base. • The normal average is 78±3 (normal or orthognathic
mandible). • The angle is above the normal range, it would be
prognathic mandible.• The angle is below the normal range, it would be
retrognathic mandible.
A. Sagittal basal relationships ( anterior-posterior ).
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3. ANB:
• This angle is the difference between SNA and SNB angle and indicates the amount of skeletal discrepancy between maxilla and mandible in antero-posterior position.
• The normal average is 3 ±2 (skeletal class I). • A larger than normal angle would indicate a skeletal
class II.• Smaller than 1 angle a skeletal class III.
A. Sagittal basal relationships ( anterior-posterior ).
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4. Wits appraisal:
• perpendicular lines on a tracing of a lateral cephalogram from points A and B, onto the bisecting occlusal plane.
• measuring the distance between the two points of intersection of the two perpendicular lines with the bisecting occlusal plane, along the latter. The greater the deviation of this reading from 0 ±2 mm in females and 1 ±2 mm in males.
• More than normal, Skeletal Class II• Less than normal, Skeletal Class III
A. Sagittal basal relationships ( anterior-posterior ).
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5. Angle of convexity (NAPog):
• assessing the degree of convexity (or concavity) of the skeletal profile.
• The angle is formed by the lines NA and A-Pog and has a positive value in convex and negative value in concave profiles, whereas in patients with a straight profile the angle is approximately 0.
A. Sagittal basal relationships ( anterior-posterior ).
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6. Cranial base angle (NSBa, Saddle angle):
• The angle between the anterior and posterior cranial base, recorded as the inferior angle formed by the intersection of the lines BaS and SN.
• A large cranial base angle is thought to signify a posterior condylar and glenoid fossa position and a mandible that is positioned posteriorly with respect to the cranial base and the maxilla, unless it is compensated by a larger gonial angle and an increased mandibular length.
• Normal, Increased, decreased Cranial base angle.
A. Sagittal basal relationships ( anterior-posterior ).
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Measuring
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1. Skeletal Analysis: B. Vertical basal relationships:1. SN-Mxpl. 2. SN-Mnpl.3. MMpA.4. Gonial angle (Angle of the mandible, Condylar angle).5. Facial Proportion (FP).
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B. Vertical basal relationships:1. SN-Mxpl: • Measured at the intersection of SN line
to maxillary plane.
• It expresses the vertical inclination of the maxilla in relation to the anterior cranial base.
• The mean value is 8 ±3 (normal inclined maxilla).
• values greater than normal indicate a posterior inclination of the maxilla.
• Smaller values indicate an anterior inclination of maxilla.
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B. Vertical basal relationships:2. SN-Mnpl:
• Measured at the intersection of SN plane and mandibular plane.
• The mean value is 32 ±4 (normal inclined mandible).
• Angles greater than normal indicate the mandible is growing downward and backward (posterior inclination of the mandible).
• Angles less than normal indicate an anterior inclination of the mandible, (mandible is growing forward and upward, anterior inclination of the mandible).
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B. Vertical basal relationships:3. MMpA:
• Measured at the intersection of the maxillary plane with the mandibular plane and relates the inclination of the mandible and the maxilla to each other. The mean value is 27 ±4 (normal interbasal angle).
• If the angle exceeds the normal there is skeletal open bite.
• whereas an angle less than the mean indicates skeletal deep bite.
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B. Vertical basal relationships:4. Gonial angle (Angle of the mandible, Condylar angle):
• The anterior angle formed by the intersection of a line tangent to the posterior border of the ramus and the mandibular plane.
• It determines the degree of inclination of the ramus to the mandibular plane and may give an indication about mandibular growth direction. (Alternatively measured as the angle between Ar-Go and Go-Gn).
• Incre??????????
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B. Vertical basal relationships:5. Facial Proportion (FP): • Lower facial height: This is a linear measurement
from menton perpendicular to maxillary plane.
• Upper facial height: This is a linear distance is measured from Nasion perpendicular to maxillary plane.
• Total facial height = lower facial height + upper facial height.
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B. Vertical basal relationships:5. Facial Proportion (FP): • FP = Lower Facial Height \ Total Facial Height *
100
• In normal faces this index has a value of about 55% ± 2% (normal lower height).
• A larger than this ratio will indicate increased lower facial height.
• Smaller than this value will indicate decreased lower facial height.
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Measuring
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Break :)
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2. Dentoalveolar relationships:1. Uinc-Mxpl.
2. Uinc-NA.
3. Uinc-to- A-Pog distance.
4. Linc to MnPL.
5. Linc-NB.
6. Linc to A-Pog.
7. Uinc-Linc.
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Overjet & Overbite: 2 ± 2
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2. Dentoalveolar relationships:1. Uinc-Mxpl: • Measured at the intersection of long axis of the the
most prominent upper central incisor with the maxillary plane.
• It evaluates the antero-posterior inclination of the maxillary central incisor.
• This angle averages 109 ± 6 (normal inclination of upper incisor).
• A larger than normal angle would indicate proclination of the upper central incisor
• Smaller than normal angle would indicate retroclination of maxillary incisors.
•
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2. Dentoalveolar relationships:2. Uinc-NA:
• This is a linear distance measured in millimeter from the most prominent incisal edge of the upper incisor perpendicular to NA line.
• It averages 4±2mm (normal position of upper incisor).
• A larger than normal angle would indicate protrusion of upper central incisor
• Smaller than normal angle would indicate retrusion of the central incisor.
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2. Dentoalveolar relationships:3. Uinc-to- A-Pog distance:
• The perpendicular distance (in mm) of the incisal edge of the maxillary central incisors to the A-Pog line.
• A measurement of the Downs analysis, expressing the degree of protrusion of the maxillary central incisors.
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2. Dentoalveolar relationships:4. Linc to MnPL: • Measured at the intersection of the long axis of the
most prominent lower central incisor with mandibular plane.
• It evaluates the antero-posterior inclination of the mandibular central incisor.
• A larger than normal angle would indicate proclination of lower incisor
• Smaller than normal angle would indicate retroclination of the mandibular incisor.
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2. Dentoalveolar relationships:5. Linc-NB:
• This is a linear distance measured in millimeter from the most prominent incisal edge of the lower incisor perpendicular to NB line.
• It averages 4±2mm (normal position of lower incisor).
• A larger than normal angle would indicate protrusion of lower central incisor and
• Smaller than normal angle would indicate retrusion of the mandibular incisor.
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2. Dentoalveolar relationships:6. Linc to A-Pog: • This is a linear distance measured in millimeter
from the incisal edge of the lower incisor perpendicular to A-Pog line.
• This measurement averages +1±2 mm (normal position of lower incisor).
• A larger than normal measurment would indicate protrusion of lower central incisor.
• Smaller than normal would indicate retrusion of the mandibular incisor.
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2. Dentoalveolar relationships:7. Uinc-Linc:
• The interincisal angle measure at the junction of the long axis of upper central incisor with the lower central incisor.
• It averages 135 ±5 (normal proclination of upper and lower central incisors).
• The angle decreases with proclination of upper and lower incisors
• The angle increase with retroclination of incisors.
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Measuring
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3. Soft Tissue Relationship: 1. Interlabial gap.
2. Upper Lip-EL.
3. Lower Lip-EL.
4. Nasolabial angle (NLA).
5. Labiomental angle.
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3. Soft Tissue Relationship: 1. Interlabial gap:
• The vertical distance between the upper and lower lip, measured with the lips at rest.
• Normal 0-2.• more than 2 Incompetent lip position.
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3. Soft Tissue Relationship: 2. Upper Lip-EL:
• This is a linear distance measured from the most anterior point on the upper lip perpendicular to esthetic plane (tip of the nose to the soft tissue pogonion)).
• It averages -2 to -4 (normal position of upper lip which is inside the line).
• A larger angle indicates the protrusion of the upper lip
• Smaller angle indicates the retrusion of the upper lip.
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3. Soft Tissue Relationship: 3. Lower Lip-EL:
• This is a linear measurement from the most anterior point on the lower lip perpendicular to esthetic plane.
• It averages from 0 to -2 inside the esthetic line (normal position of the lower lip).
• A larger measurment indicates the protrusion of the lower.
• Smaller indicates the retrusion of the lower lip.
• According to R. M. Ricketts, the lower lip should fall slightly ahead of the upper lip when related to this line.
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3. Soft Tissue Relationship: 4. Nasolabial angle (NLA):
• The anterior inferior angle formed by the intersection of a line tangent to the columella of the nose and a line drawn from subnasale to the mucocutaneous border of the upper lip.
• It evaluates the degree of protrusion or retrusion of the upper lip, in reference to the columella of the nose.
• The nasolabial angle can influence the decision for extractions as part of the orthodontic treatment plan, as it is partially dependent on the anteroposterior position of the maxillary incisors.
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3. Soft Tissue Relationship: 4. Nasolabial angle (90-100°):
>norm obtuse nasolabial angle.
Norm normal nasolabial angle.
<norm acute nasolabial angle.
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3. Soft Tissue Relationship: 5. Labiomental angle:
Deep Labiomental angle.
Normal Labiomental angle.
Shallow Labiomental angle.
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Measuring
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