Visual-DxÓ Ceph Analysis

Ted Rothstein DDS, PhD

1. Trace your patient’s radiograph.
2. Select the standard most suitable for age and sex.
3. On your tracing locate point Sella.
4. On your tracing, locate point Occipitale (the lowest point on the occipital bone) and Maxillon ("directly below" the key ridge and midway between the superior and inferior contours of the palate). Draw a line connecting these two points. This line is the K-W Plane of Orientation (K-W P of O).
5. Superimpose (register) (overlay) Sella^tracing on Sella^standard and position tracing so that

K-W P of O^tracing is made parallel to the K-W P of O^standard. The tracing is now oriented in the Standard-Tracing Observation Position (STOP).

                                                     A. Use STOP, or as an option, if the locus of Nasion is assumed to be in "normal" position, you can

B. Register Nasion^tracing on Nasion^standard with K-W P of O^tracing parallel to the
K-W P of O^standard to obtain information about the anterior-posterior relation of the Maxilla and the Mandible relative to the Anterior Cranial Base.

C. Observe where the end point^tracing lies in relation to the mean and its standard deviation arms^standard and then mark it using the diagram of boxes provided.

Suggestion: Using the 9 x 3 grid of boxes provided on the analysis sheet, place a dot (· ) in the box that best describes the anterior-posterior position of the points Nas, A and B or Pog. Connect the dots. Choose the words that best describe your patient’s skeletal profile (See the Visual-Dx Analysis sheet). For example an arrangement of points Nas ^tracing, A ^tracing and B ^tracing which denotes "moderate prognathic" skeletal profile would appear as shown:

                                               

Total Ant. Face Ht.: (Nas-Me)

A. Use STOP or

B. Register Nas^tracing on Nas^standard and make K-W P of O^tracing parallel to the K-W P of O^standard.

C. Observe where the end point^tracing lies in relation to the mean and its standard deviation arms^standard and
then mark it using the diagram of boxes provided.

Dentition-Max.:

B. Register apex of U1^tracing on U1^standard and make K-W P of O^tracing parallel to the K-W P of O^standard

Dentition-Man.:

B. Register apex of L1^tracing on apex of L1^standard and make Go-Gn^tracing parallel to
Go-Gn^standard.

A. Use STOP to assess:

Register Ar^tracing on Ar^standard and superimpose Ar-Go^tracing on Ar-Go^standard.

C. For symphyseal height and chin button: register Me^tracing on Me^standard and make
K-W P of O^tracing parallel to the K-W P of O^standard.

Usefulness of the SD (standard deviation) crosses on each Normal standard

1. The cross marks of the standard deviation are centered on the mean location of the end point and show in actual size ± 1 SD in the horizontal and vertical directions. Such a visualization of the range of normal variation helps you to graphically characterize the extent of your patient’s deviation from the mean.
1. Accuracy of the reproduced standard may be verified by comparing the actual computed X and Y coordinate measurement of point A (shown on the standard) with the X and Y coordinate measurements you can measure for point A on the standard you have.

Features of the standards:

1. Age and Sex Specific

1. Mandibular size (ramus, corpus), form, position, inclination (MPA) and rotation
2. Horizontal and vertical position of molars and incisors
3. Total facial height (ant. and post); upper facial height; lower facial height
4. Anterior cranial base length

3. Provides insight into angular data that don’t "fit"; Now you can understand why angular measurement employing Nasion are so deceptive. For example in the study, angle S-N-A was not statistically different between all the samples of Class II and the controls except for the 10 year old males with Class II whose S-N-A angle was significantly larger than the controls. The reason became apparent when you examined the means for S-N and S-A along the X-axis: In the Class II male sample S-N was significantly larger while S-A showed no statistical difference when compared to the normal controls. These standards make you aware of where your patient fits along the spectrum of size differential for anterior cranial base length which is extremely important in the interpretation of angles which include Nasion.
4. You can determine the true reason for the Class II or Class III and pinpoint which jaw is the one that is oversized or undersized.
5. No actual measurements are required; the composite in toto is the norm. If you desire having numerical or angular norms either measure them on the standard or look them up in the dissertation.
6. Relative ease of use: overlay your tracing (or simply the end points you are interested in) on the standard using STOP (see above).
7. Interpretation is based on visual comparison of size, form and position.
8. Understanding of the mandibular parameters that are deviant is enhanced.