SECTION I — WHAT TO SEND TO FMBODS

Before the case is sent to FMBODS for analysis, certain information is normally recorded by the orthodontist from his clinical examination and/or plaster models.

a. Lips and mouth

b. Musculature

c. Arch form

d. Other history

A wax impression may be made of the lower arch using the special FMBODS plastic-backed wax wafer and sent to FMBODS. Remove the water from the plastic bag. Place the wafer in hot water for approximately one minute. Remove from the water and apply as one would a regular impression tray. Label it with the patient’s name. Replace it in the plastic bag. No special procedure is necessary in packaging the wafer, as the plastic tray protects it. Placing it in the plastic bag ensures that the wax will not mar the X-rays.

The wax wafer is used by FMBODS technicians for an arch length analysis by measuring imbrication. If deciduous teeth are present, a correction for “E” space will be made using Moyer/Wylie correlations between widths of incisors vs. canines and bicuspids at the 50 percent probability level, i.e., the error in the estimate is as likely to be on the high side as on the low side. The error for this method is usually within 2mm.

The history sheet is for the doctor’s use as a checklist and also to store extensive records for your data bank. It should be completed at the time of the clinical examination. It is optional and may be filled out partially, completely, or not at all, if preferred. The more data you feed into your data bank, the more value there will be in the future.

The illustration below shows a completed order form requesting only the materials discussed in this manual. Other materials will be discussed in other publications.

The order form requests birthdate, race, X-ray date, and the assumptions for the Visual Treatment Objective (V.T.O.).

You may specify the assumptions of the work-up, such as extraction, high pull headgear, if you wish, or have the computer formulate an assumption based upon the mechanical logic explained later on.

If you wish to perform your own arch length analysis rather than sending a wax bite, you must enter the resulting shortage or excess on the order form.

It is most important that the doctor note any missing or supernumerary teeth, or any other unusual circumstances, as it is easy to make errors in tracing if these are not recognized.

The frontal and lateral headplates are then to be sent along with the order form, history sheet and wax wafer in the blue envelope provided. You will receive materials for 20 cases initially and additional materials after every tenth case.

If necessary, a wrist plate may also be included to evaluate skeletal age. Assessing skeletal maturity can be valuable for patients when determining growth potential or when maturation timing is a significant factor in the clinical assessment.

The illustrations below show the proper positioning for the frontal and lateral head-plates. The lateral assumes the patient’s cheek to be as close to the film as possible. The frontal should be aligned using a ruler. A line is scribed on the head holder 15mm above the ear rod and parallel to the ground. The ruler is used to extend this line to the canthus of the eye, as shown. Note that the patient’s face is closest to the film, thus giving a posterior - anterior (P.A.) film.

SECTION II – RECOGNITION OF THE SOURCE OF THE MALOCCLUSION IN THE MORPHOLOGY

The first step in using the Data Systems materials is to quickly scan the tracing to get an overall feel for the case.

Seven lateral and four frontal factors are shown on the tracing. The lateral factors are:

Facial axis - the angle between the Basion-Nasion plane and the plane from Foramen Rotundum to Gnathion - this gives the direction of growth of the chin.

Facial depth - the angle between the Frankfort plane and the facial plane N-Po.

Convexity - the distance between Pt A and the facial plane N-Po. This measures the horizontal relation between the upper and lower jaws.

Mandibular plane angle to Frankfort plane.

Lower incisor to A/Po - this gives the position of the lower arch in the jaw.

Upper molar position - the distance between the pterygoid vertical and the distal of the upper first molar.

Interincisal angle - the angle defined by the long axis of the central incisors. This gives the protrusion of the incisors.

The frontal factors include:

Intermolar width (lower arch).

Midline asymmetry - upper to lower incisor midlines.

Maxillo - mandibular width, right and left, to compare the relative widths of the upper and lower jaws.

This gives a basic description of the case today, and is the first step in the analysis.

COMPREHENSIVE CEPHALOMETRIC DESCRIPTION

The second analysis is the 50-factor comprehensive description. This is intended for an in-depth study of the problem areas. The use of individual factors will be discussed later.

You will notice that the factors in the printout (pg. 8-9) are given generalized conceptual names so that the actual points of measurement need not be memorized. The column "Clinical Deviations from the Norm" gives a degree of severity for each factor. The normal range is by definition -1 to +1, and severe abnormalities are those in excess of ±2. For consistency, we always measure the upper arch to the lower arch. A positive quantity indicates protrusion, prognathism, or mesial position as appropriate for each factor. A negative quantity indicates retrusion, retrognathism or distal position.

The norms are selected for the individual based upon age, sex, size (facial volume), and race.

THE COMPUTER PROBLEM ANALYSIS

The real importance of the cephalometric measurements is in their use in pinpointing the problems of the cases:

Thus, the computer provides a cephalometric interpretation of the printout. We call it our Computer Problem Analysis.

It groups orthodontic problems into five classifications, i.e.:

Horizontal - Class II, Class III.

Vertical - Open and deep bites.

Transverse - Crossbites.

Symmetry - Midline shifts.

Contributory problems such as TMJ, lip sucking, and thumb sucking.

The analysis of each problem tells in words if there are cephalometric indications of the following:

Whether you have a malocclusion.

Whether the malocclusion is due to the lower or upper arch.

Whether the problem is skeletal.

Whether the skeletal problem is due to the lower or upper jaw.

This verbal discussion will be based upon an analysis of all 50 factors or more of the Comprehensive Cephalometric Description.

USING THE FMBODS COMPUTER PROBLEM ANALYSIS

(See page for definitions of landmarks)

I. HORIZONTAL PROBLEMS

(1)

Clinical Question:

Is there a Class II, Class III malocclusion?

Measurement:

Molar relation

Canine relation

Overjet (Field I)

Illustration:

Treatment Implication:

Basic directions of treatment

(2)

Clinical Question:

Is the problem due to the upper or lower molars?

Measurement:

Upper molar position (Field III)

Illustration:

Treatment Implication:

Class II due to upper implies good non-ext. HG case. Due to lower implies would not want to move lower molar distally to gain arch length. Would prefer to treat moving lower forward.

(3)

Clinical Question:

Is the problem skeletal?

Measurement:

Convexity (Field II)

Illustration:

Treatment Implication:

If normal skeletal implies avoid use of headgear (Orthopedic force).

(4)

Clinical Question:

Is the skeletal problem due to the maxilla or mandible?

Measurement:

Maxillary depth

Facial depth

Confirmed by:

anterior cranial base length corpus length ramus position mandibular arc porion location(Field V & VI)

Illustration:

Treatment Implication:

Skeletal Class II due to maxilla implies good prognosis for HG early correction.

Due to mandible implies poor prognosis, try to minimize rotation during treatment. Class III due to forward ramus position and porion location implies probable excessive mandibular growth in future.

II. VERTICAL PROBLEMS

(1)

Clinical Question:

Is there a deep or open overbite?

Measurement:

Overbite (Field I)

Illustration:

Treatment Implication:

Basic directions of treatment

(2)

Clinical Question:

Is it due to the upper or lower incisor?

Measurement:

Lower incisore

Extrusion (Field I)

Lip embrasure to occlusal plane

Illustration:

Treatment Implication:

Should the upper or lower incisor be intruded? (Check growth forecast for amount and direction.)

(3)

Clinical Question:

Is there an open or deep bite skeletal pattern?

Measurement:

Lower face height (Field II)

Illustration:

Treatment Implication:

Will growth be causing a problem in treatment? Is the dental problem skeletal?

(4)

Clinical Question:

Is the skeletal open or deep bite due to the maxilla or mandible?

Measurement:

Mandibular plane

Palatal plane

Maxillary height

Mandibular arc

Illustration:

Treatment Implication:

Deep bite due to mandible implies cervical traction, open bite due to mandible implies high pull H.G., open bite due to tipped palate cervical H.G.

III. TRANSVERSE PROBLEMS

(1)

Clinical Question:

Is there a lingual or buccal crossbite?

Measurement:

Molar relation left and right (Field I)

Treatment:

Basic directions of treatment.

Clinical Question:

Is the crossbite due to the lower or upper arch?

Measurement:

Molar to jaw left and right (Field III)

Treatment:

Lower arch width for this individual’s jaws implies a poor case for buccal expansion. (Unless the upper jaw can be widened.)

Illustration:

(2)

Clinical Question:

Is there a “skeletal” crossbite?

Measurement:

Maxillo-mandibular width left and right (Field II) confirmed by maxilla proportion and mandible proportion (Field VI)

Illustration:

Treatment Implication:

Skeletal lingual crossbite implies orthopedic expansion

Crossbite not skeletal implies habit pattern must be alleviated and healthy oral environment created

(3)

Clinical Question:

Is the skeletal crossbite due to the maxilla or mandible?

Measurement:

Maxilla proportion

Mandible proportion

Illustration:

Treatment Implication:

Skeletal crossbite due to narrow maxilla better orthopedic expansion.

IV. SYMMETRY

(1)

Clinical Question:

Is there a midline shift?

Measurement:

Denture midline (Field I).

Illustration:

Treatment Implication:

Basic directions of treatment.

(2)

Clinical Question:

Is the shift dental discrepancy or a positional shift of the mandible?

Measurement:

Maxillo-mandibular midline (Field II).

Illustration:

Treatment Implication:

Denotes degree of difficulty.

(3)

Clinical Question:

Is the asymmetry skeletal?

Measurement:

Occlusal plane tilt (Field III)

Postural symmetry (Field V)

Antigonial height

Illustration:

Treatment Implication:

Possible unilateral extractions or surgery. Should retake frontal to verify positioning if postural asymmetry.

POSSIBLE CONTRIBUTORY PROBLEM

(1)

Theory:

Low tongue position - causing a wide lower arch and narrow upper. The key is crossbite due to environmental rather than skeletal causes.

Measurement:

Molar relation (left and right)

Maxillo-mandibular width (left and right)

Molar to jaw (left and right)

Illustration:

(2)

Theory:

Mouth breathing - similar to above with a narrow nasal cavity.

Measurement:

Nasal width

Plus the above measurements

Illustration:

(3)

Theory:

TMJ growth problem - cephalometric clues are skeletal asymmetry, short ramus.

Measurement:

Posterior face height

Mandibular arc

Occlusal plane tilt

Postural symmetry

Illustration:

(4)

Theory:

Thumb sucking - protrusive upper incisor, maxillary alveolar protrusion.

Measurement:

Maxillary incisor protrusion

Maxillary depth

Maxillary height

Overjet

Illustration:

(5)

Theory:

Microrhinodysplasia - palate tipped upward - narrow nasal cavity.

Measurement:

Palatal plane

Nasal width

Illustration:

(6)

Theory:

Pathologic Class III growth - this type tends to grow more in the mandible and less in the maxilla than normal.

Measurement:

Ramus position

Porion location

Illustration:

(7)

Theory:

Condyle forward in fossa - false bite.

Measurement:

Distance from the distal of the condyle to the porion.

Illustration:

SECTION III - PRELIMINARY SELECTION OF TREATMENT ALTERNATIVES

The service can make a preliminary selection among various treatment alternatives, assuming:

You would wish to have the treatment method that would tend to move toward the normal range.

You would prefer not to extract if the patient can be treated within the normal ranges without extraction.

The problem analysis then tells whether the following possibilities would be indicated, not indicated, or neutral:

"Neutral" implies that the cephalometric indications are neither clearly in favor of; or against the considered therapy. Therefore, considerations other than cephalometrics must form the basis of the decision.

High pull headgear - indicated on open-bite patterns, due to the mandible

Cervical headgear - indicated on deep bite patterns or cases where it is desirable to tip the palate.

Activator - indicated on deep-bite Class II with square jaws, retruded lower incisor when moderate convexity change is required.

Buccal expansion lower arch - indicates when the lower arch is narrow compared with the skeletal pattern.

Palate expansion - indicated when orthopedic expansion is desired.

Lower molar distal movement - indicated when the lower molar is forward, and more arch length is required. A maximum of 2mm may be suggested.

The service then provides an analysis of the factors involved in extraction:

Lower arch length shortage or excess - from the wax bite or supplied by you.

Effect of positioning lower incisor at +1 to A/Po after growth and convexity change (2mm arch length per mm incisor movement).

Effect of compromising convexity at the end of the normal range.

Possible compromise of the lower incisor depending upon the facial pattern.

Possible arch length gain through buccal expansion of molars and bicuspids to the end of the normal range (actually +.5CD on each side).

The total arch length shortage or excess after all compromises.

If there is still a shortage, the computer will assume extraction for your consideration. If excess, non-extraction in the lower arch.

The computer will then evaluate:

The predicted position of the upper molar, assuming non-extraction. If eventually there is not sufficient room for the second (12mm) and third molars (20mm) at the end of growth, it will indicate extraction in the upper arch*.

*Assumes average-sized teeth - smaller teeth will require less space.

The facial pattern will be evaluated. In a vertical pattern, less compromise of the incisors from the norm will be allowed; in a horizontal pattern, a more protrusive incisor will be allowed

The result is a readable summary of what cephalometrics has to say about the case

However, it should not be considered a complete diagnosis as many other factors, which are not cephalometric, must be evaluated in the final decision, such as musculature, tissue health, and cooperation. Further, while the FMBODS analysis is believed to be the most thorough analysis available, the interpretations may not agree with other cephalometric analyses based upon other reference frames.

PRELIMINARY SELECTION OF TREATMENT ALTERNATIVES

(1)

Clinical Decision:

Choices of headgear.

Theory:

Headgear assumed in Class II if convexity reduction is desired.

Cervical is indicated in deep bite cases with a deep bite skeletal pattern, good horizontal growth expected or, if the palatal plane is tipped upward.

High pull is indicated in open bite cases with open bite skeletal patterns or vertical growth due to the mandible.

Measurements:

Overbite

Lower face height

Facial axis

Mandibular plane

Palatal plane

Posterior face height

Mandibular arc

Convexity

Molar relation

Illustration:

(2)

Clinical Decision:

Activator.

Theory:

Activator recommended in deep bite facial pattern with square jaw, retruded lower incisor, moderate convexity, Class II.

Measurements:

Molar relation

Convexity

Lower incisor protrusion

Lower face height

Mandibular arc

Illustration:

(3)

Clinical Decision:

Buccal Expansion Lower Arch.

Theory:

Buccal expansion is preferred in cases with good growth potential and a narrow lower arch for facial type.

Measurements:

Molar to jaw (left and right) facial axis age.

Illustration:

(4)

Clinical Decision:

Palate expansion is preferred in cases of severe crossbite with a narrow maxilla and a narrow nasal cavity. Preferably in a deep bite pattern due to the tendency to open bite.

Theory:

Molar relation (left and right)

Maxillo-mandibular wide

Measurements:

Molar relation (left and right)

Maxillo-mandibular width (left and right)

Nasal width

Facial axis

Overbite

Illustration:

(PRELIMINARY SELECTION - Cont’d)

EXTRACTION—CONSIDERING FACTORS FOR INCREASING ARCH LENGTH

(1)

Arch Length Factor:

Lower arch length discrepancy (Model arch length)

Theory & Calculation:

Measured from wax bite - the total imbrication less spaces is calculated using calipers. If deciduous teeth, we use Wylie/Moyer correlation to estimate 3, 4, 5. Accuracy: Normally \(\pm \) 2mm for correlation.

Illustration:

(2)

Arch Length Factor:

Position lower incisor at ideal to A/Po. (Cephalometric Arch Length)

Theory & Calculation:

Each 1mm incisor movement changes arch length 2mm. Using a growth forecast, we locate the expected position of Pogonion and the desired position of Point A (maxilla) after treatment, and the new occlusal plane. The ideal position of the lower incisor is then 1mm ahead of the "ideal" A/Po plane. We then calculate the mm lingual or labial movement to achieve this ideal.

Illustration:

(3)

Arch Length Factor:

Possible gain through convexity compromise.

Theory & Calculation:

Each mm of retraction of Point A due to orthopedic force causes a \(1/2\)mm lingual movement of the A/Po plane at the occlusal plane. This necessitates a \(1/2\)mm lingual movement of the lower incisor to maintain a +1mm to A/Po and thus 1mm loss of arch length. Thus, if arch length is required, we may accept a more forward position of Point A. If necessary, the computer will accept a +4mm convexity maximum, if attainable.

Illustration:

(4)

Arch Length Factor:

Possible gain through lower incisor compromise.

Theory & Calculation:

The normal range of lower incisor to A/Po is +1mm \(\pm \) 2mm or -1 to +3. We may, therefore, move the incisor to +3 to A/Po and gain 4mm of arch length still within normal ranges. The computer will accept a greater compromise in brachyfacial patterns, less in vertical patterns.

Illustration:

(5)

Arch Length Factor:

Gain through expansion of molars & bicuspids.

Theory & Calculation:

After evaluating the width of the lower molars to the jaws, the computer calculates the expansion allowable in molars to ᐩ ½ clinical deviation on each side. For each 4mm molar expansion, it assumes 3 mm second bicuspids and 2 mm first bicuspids for an arch length gain of 3 mm along the entire arch.

Illustration:

(6)

Arch Length Factor:

Possible gain through retraction of the lower molar.

Theory & Calculation:

Each mm lower 6 distal movement is 2 mm arch length gain. Computer calculates "norm" for lower molar and will allow retraction to 1½ mm distal to that norm (age 6 mm. A maximum of 2 mm will be suggested.

Illustration:

(7)

Arch Length Factor:

Total arch length discrepancy after compromise.

Theory & Calculation:

Gives the resulting shortage or excess if all above factors are compromised to limits of the normal ranges. "-mm" indicates the case could not be treated non-extraction within normal cephalometric ranges.

Illustration:

SPACE FOR UPPER MOLAR IF NON-EXTRACTION

The distance at maturity between the pterygoid vertical (PTV) and the upper first molar is critical for the successful eruption of the upper second and third molars. There is less than a 10 percent chance of successful eruption of third molars if the distance is less than 20mm. Second molars require a minimum of 12 mm.*

The expected space available is calculated as follows:

The position of the lower molar in space is predicted for the duration of treatment with normal growth

This is corrected for mandibular rotation during treatment and,

Desired mesial or distal movement during treatment to give the expected position of the lower molar without treatment

The upper molar is then placed in a Class I to the lower and,

The amount and direction of growth to maturity of the upper molar is estimated to give the final expected position

The predicted position compared to the PTV is then calculated.

*Not applicable in cases with unusually small or large teeth

SECTION IV — A STATEMENT OF SPECIFIC OBJECTIVES

THE VISUAL TREATMENT OBJECTIVE (CEPHALOMETRIC SETUP).

The next step in the FMBODS system is to arrive at a specific objective for this individual patient at the end of treatment, recognizing:

His expected amount and directions of growth.

The preliminary selection of treatment alternatives in Section III (orthopedics).

The expected result of the above on his growth pattern during treatment.

Arch length shortage.

A denture location and occlusion within the cephalometric "normal ranges".

Changes in the soft tissue profile due to tooth movement.

The ideal treatment objective is then an objective that has stood the test of logic; it places the plan on paper where you can visualize interrelationships to help you test your plan before beginning treatment. It must then be tested against other biological, cooperative, and mechanical factors by the orthodontist before a final diagnosis can be made.

SPECIFIC INFORMATION ON YOUR VTO

On your red VTO tracing (Growth Forecast with Treatment), you will find several items of information:

Displayed are two numbers in the form 24 months, 2.0 modules. The first refers to the number of months of growth requested. The second is the "equivalent" units of growth expected for this patient, based upon his age (preferably skeletal age) and sex. One module is equal to the average yearly growth of boys and girls between the ages of 8 and 13. Thus, 24 months, 3 modules might be typical for a boy during the spurt, 24 months, .5 modules would apply to a 14-year-old girl, 24 months, 2.0 modules to a girl age 9.

The label on the tracing gives the assumptions used in drawing up the V.T.O. by the technician. These will generally agree with the computer summary but will be rounded off to the nearest ½ mm.

While the computer may call for molar movement of "2.7", this is only for machine accuracy and is impractical.

One special situation should be noted. If the lower arch can be treated within normal ranges, but extraction is indicated in the upper arch, the doctor may wish to extract in the upper arch only, leaving the case in a Class II, or extract the second or the third molars, obtaining a Class I. This molar will be shown as a Class I on the forecast, but with diagonal lines indicating you may wish to leave it in a Class II.

The technician will also check the "reasonableness" of the computer assumptions in terms of treatment limitations. In addition, the final esthetic appearance will be evaluated, and if you give us special instructions, the decision to extract in borderline cases could be made according to your esthetic preferences, measured by the lower lip to the esthetic plane. We could change an extraction to a non-extraction if the profile is too flat (compared to the esthetic plane), or change a non-extraction case to an extraction if it is too full.

The lower lip to the E plane will form the basis of this evaluation.

HOW THE COMPUTER PREPARES A V.T.O.

Calculate the expected units of growth during the treatment period as a function of skeletal age and sex.

Grow the patient without treatment. (Each point has its own rate of growth & direction.) Establish assumptions of orthopedics - headgear, palate split, etc.

Rotate mandible for treatment effects due to the above, assuming non-extraction. The first trial by the computer is always non-extraction unless instructed by the doctor.

Select a reasonable objective for the maxilla accounting for growth, age, limitations of orthopedics, and cephalometric standards (2mm ±2mm convexity) based upon the expected position of the mandible. Draw the ideal A/Po plane.

Change the occlusal plane if necessary to blend with the lip embrasure (computer will go halfway to the ideal).

Measure arch length discrepancy from models or wax bite.

Position the lower incisor to "ideal" +1mm to A/Po, and 22°.

Calculate the effect on the arch length of "ideal" position.

If the "model" arch length discrepancy plus ideal incisor position shows a resulting shortage, consider gaining arch length through:

Compromising convexity to +4mm, thus allowing a more forward A/Po plane and a more labial ideal position.

Compromising lower incisor to +3 (or as allowed by facial pattern)

Buccal expansion (see criteria)

You gain 1mm arch length with each

4mm Molar Expansion

3mm 1st bicuspids

2mm 2nd bicuspids

Lower molar distal movement (see criteria)

If the above will accommodate tooth mass within normal limits of lower molar and lower incisor positions, continue the non-extraction assumption; if not, assume extraction.

If extraction

Position the lower molar to account for arch length excess.

Assume loss of two lower bicuspids

(Average 14mm)

Reduce mandibular rotation for extraction. This assumes you use mechanics that prevent the eruption of the lower molars.

Place the upper molar in Class I to lower and extend the prediction to maturity.

Check the upper molar prediction to PTV at maturity. Is there adequate room? If not, extraction in the upper arch may be indicated, due to probable interference with the 2nd and 3rd molars.

Place the upper incisor at a 2½ mm overbite and overjet and 130° to the lower.

Complete soft tissue to conform to tooth movement.

Check esthetics. Is the result too flat or too protrusive?

SECTION V – YOUR FINAL INDIVIDUALIZED TREATMENT PLAN CHOICE USING THE TREATMENT OBJECTIVE ANALYSIS OVERLAYS

The essentials of the V.T.O. are displayed on the treatment objective analysis sheet. This overlay shows graphically where the patient is now (white), where he will be without treatment (shaded), and where you would have to treat him in order to obtain the objectives (stripes). On the actual overlay sent with the case, these are respectively: before treatment - blue; growth without treatment - green; treatment objective - red. It compares:

Profile change (superimposed on the esthetic plane).

Direction of growth of the chin and position of the upper molar (superimposed on the Basion-Nasion planes at PTV).

The maxilla (superimposed along Basion-Nasion at Nasion).

The maxillary dentition (superimposed on the palate).

The mandibular dentition is superimposed along the corpus axis at the pogonion.

It can be seen from this overlay what direction the mechanical force must take and whether natural growth will be working for or against the mechanical effect. Our subscribers have found this sheet to be the most useful aspect of the service for treatment planning and visualization of mechanics.

The next step is to accept or reject the V.T.O.

Can you accomplish the required movement mechanically?

Will the patient adapt to the new tooth positions?

Does the proposed treatment meet your esthetic requirements?

When you have decided on an objective that is desirable and feasible, you can then plan the mechanics necessary to achieve it.

You can visualize intrusion, distal movement, holding against growth, or allowing growth to do the work for you.

ILLUSTRATION

ILLUSTRATION

ILLUSTRATION

ILLUSTRATION

ILLUSTRATION

SECTION VI – MONITORING YOUR CASE USING THE TREATMENT OBJECTIVE ANALYSIS OVERLAYS.

The fact that you have a specific roadmap telling you where you are now and where you want to be gives you a useful tool to monitor patient progress.

At 6-8 month intervals, a progress headplate can be taken. Using the Treatment Analysis overlays, there is no need to trace the progress headplate, nor take measurements. It will be sufficient just to lay the overlays on the progress headplate over a light box.

For short-range progress X-rays, you may substitute areas more easily seen than the areas of superposition used for long-range growth that might be difficult to locate on an X-ray, i.e., PT point, XI point, etc.

Thus, checking the progress of the upper molar and chin, you may superimpose on S-N at S. (You may have to pick a point between the red and blue nasions.)

To check the movement of the lower incisor and molar, you may superimpose on the symphysis.

To check the movement of the maxilla, superimpose on S-N at N if the basion is difficult to locate.

By visualizing where you are now, where you would be without treatment (normal growth), and the objective, you will be able to distinguish between lack of growth, poor reaction to mechanics, or lack of cooperation by noting whether progress is in the treated or untreated direction.

Finally, when the case is completed, the overlays will tell you how close the case came to the objective.

You can then consider the reasons and utilize the information in setting and accomplishing individual treatment objectives for future patients.

FIGURE 1. LATERAL TRACING (CEPHALOMETRIC POINTS)

*) Point location not stored; used for QC measurement checks

FIGURE 2. FRONTAL TRACING (CEPHALOMETRIC POINTS)

SECTION VII – DEFINITIONS OF LANDMARKS

LATERAL CEPHALOMETRIC ANALYSIS POINTS (Part 1)

LATERAL CEPHALOMETRIC ANALYSIS POINTS (Part 2, Cont.)

LATERAL CEPHALOMETRIC ANALYSIS PLANES

FRONTAL CEPHALOMETRIC ANALYSIS POINTS

A3 - Cuspid (left) - Tips of upper permanent canines.

3A (right)

A6 - Molar - Bilateral points on the frontal occlusal plane perpendicular to the buccal surfaces of the crowns of the upper first permanent molars. A6 - left, 6A - right.

6A

AG - Mandible - Points at the lateral inferior margin of the antigonial protuberances. AG - left, GA - right.

GA

B3 - Cuspid (left) - Tips of lower permanent canines.

3B (right)

B6 - Molar - Bilateral points on the occlusal plane perpendicular to the buccal surfaces of the crowns of the lower first permanent molars. B6 - left, 6B - right.

6B

JL - Maxilla - Bilateral points on the jugal process at the intersection of the outline of the tuberosity and zygomatic buttress. JL - left, JR - right.

JR

MM - Menton/Mandible - Point on the inferior border of the symphysis directly inferior to the mental protuberance and below the center of trigonium mentali.

NC - Nasal - Points on the outline of the nasal cavity at the widest area in frontal perspective. NC - left, CN - right.

CN

ZL - Zygomatic - Zygomatic Bilateral points on the medial margin of the zygomatico-frontal suture, at the intersections of the orbits. ZL - left, ZR - right.

ZR

ZA - Zygomatic - Zygomatic-Center of the root of the zygomatic arch, mid-points. ZA - left, AZ - right.

AZ

AN - Anterior Nasal Spine - Tip of the anterior nasal spine just below the nasal cavity and above the hard palate.

1A - Point 1A - Selected at the interdental pappilia of the upper incisors at the junction of crowns and gingiva.

1B - Point 1B - Selected at the interdental pappilia of the lower incisors at the junction of crowns and gingiva.

Occlusal Plane - Selected from the bisection of the overbite of the upper and lower first permanent molars, both left and right sides.

* In all groups of two, the first entry indicates left, the second indicates right.

(Refer to Appendix for Mathematical Definitions of Factors and notations used.)