Qassim University-College of DentisrtyOrthodontic Department

Cephalometric Analysis

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:

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:

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:

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 ).

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 ).

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 ).

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 ).

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 ).

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 ).

Measuring

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).

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.

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).

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.

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).

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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.

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.

Measuring

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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.

Overjet & Overbite: 2 ± 2

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.

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.

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.

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.

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.

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.

Measuring

3. Soft Tissue Relationship: 1. Interlabial gap.

2. Upper Lip-EL.

3. Lower Lip-EL.

4. Nasolabial angle (NLA).

5. Labiomental angle.

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.

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.

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.

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.

3. Soft Tissue Relationship: 4. Nasolabial angle (90-100°):

>norm obtuse nasolabial angle.

Norm normal nasolabial angle.

<norm acute nasolabial angle.

3. Soft Tissue Relationship: 5. Labiomental angle:

Deep Labiomental angle.

Normal Labiomental angle.

Shallow Labiomental angle.

Measuring