The soft tissue cephalometric analysis can be performed on a good quality cephalogram that shows reasonable to excellent soft tissue details of the facial profile and related structures. The cephalogram should be obtained with the lips relaxed without strain on the lips and chin. The soft tissue profile of the face can be recorded by using one of the following techniques:

• 1.

  Attaching an aluminium or copper wedge covering the area behind the soft tissue profile to block X-rays is the most used method in day-to-day practice.

• 2.

  Using a radiopaque barium meal, the same as a contrast in abdominal radiography: The barium meal is painted on the midline structures of the face from the forehead to below the chin. This technique was popular until the 1980s but is no longer used because it is a messy procedure.

• 3.

  Adapting a thin lead wire on the midline contours of the face extending from forehead to chin is another way of providing a good profile line on a cephalogram. However, it requires considerable time and experience to position the wire in such a way as to conform accurately to the facial profile.

• 4.

  Soft tissue could be recorded better by reducing kilovoltage during radiation exposure.

• 5.

  Simultaneous exposure of non-screen and screen film in the same cassette is a good way of recording hard and soft tissues.

• 6.

  Jacobson advocated reducing film density over the anterior bony landmarks using black paper in the cassette.

• 7.

  Painting an absorbing dye on the intensifying screen.

• 8.

  Arnett et al. advocated placing metallic markers on the right side of the face to mark the profile.

• 9.

  With contemporary advances in digital cephalometry, which has nearly replaced film-based cephalograms, photo editing tools are used to manage contrast sharpness and brightness which also assist to locate facial profiles on digital cephalometric pictures .

The commonly used landmarks on the soft tissue profile of a cephalogram are depicted in Fig. 27.1 .

Cephalometric landmarks of the soft tissue of the face.

The soft tissue profile can be evaluated by dividing the face into four regions for easy and methodical analysis.

• •

  upper one-third

• •

  middle one-third

• •

  lower one-third

• •

  chin/neck region

A. M. Schwarz devised a profile analysis using a lateral cephalometric radiograph in 1938. ^, He used the spina-palate plane, which separates the dentition from the skull.

Landmarks and constructed reference lines used in the Schwarz’s analysis:

Gnathic profile field (GPF)

The area between the two perpendicular lines constructed is termed the gnathic profile field (GPF) by Schwarz. The two perpendicular lines are the Pn line and the Po line.

The Pn line is drawn perpendicular to the H line at the soft tissue nasion, and the Po line is drawn perpendicular from the orbital point to the H line. According to Schwarz, H line is a soft tissue FH plane. It should not be confused with the H line of Holdaway.

Usually, the upper lip touches the Pn line, and the lower lip lies one-third posterior to the width of the GPF. In the ideal case, the T line bisects the upper lip’s vermillion border and touches the lower lip’s anterior vermillion curvature ( Fig. 27.2 ).

Profile analysis by A. M. Schwarz (1929).

(A) Normally, the upper lip touches the Pn line, and the lower lip lies one-third the width of the GPF posterior to it. (B) In the ideal case, the T line bisects the vermilion border of the upper lip and touches the anterior vermilion curvature of the lower lip.

Subtelny was the first to document downward and forward growth of the nose with maturity. He also found that not all parts of the soft tissue profile directly follow underlying skeletal structures. He studied growth changes in the facial integument, which was one of the first longitudinal cephalometric studies to include the soft tissue of the face. This analysis provides information on the convexity of the profile and distinguishes convexity among:

• •

  the skeletal profile,

• •

  the soft tissue profile,

• •

  and a complete soft tissue profile, including the nose.

Total soft tissue profile

Total soft tissue profile is measured by NS-No-PS. Convexity of the nose is included because the nose has a marked influence on the overall cosmetics of the soft tissue profile. In men, the average value is 133 degrees, while in women, it is 131 degrees. Bishara found that total facial convexity increases with age. All male and female subjects demonstrated an increase in total facial convexity from 5 years to adulthood ( Fig. 27.3 ). These are summarised as follows:

SN	Parameter		Male	Female	Remarks
1	Skeletal profile convexity	N-A-Pg	179 degrees	177 degrees
2	Soft tissue profile	NS-Sn-Pg	162 degrees	161 degrees	Stable after 6 years?
3	Total soft tissue profile	NS-No-PS	133 degrees	131 degrees	Total soft tissue profile shows an increase from 5 years to adulthood in both sexes.

Subtelny’s analysis: soft tissue facial convexity.

Steiner’s S line is drawn from the Pog to the midpoint of the S-shaped curve between the Sn and nasal tip. Usually, the upper and lower lips touch the S line. The lips resting behind this line are considered retrusive, while those lying ahead are protrusive ( Figs 27.4 and 27.5 ).

Steiner’s S line.

Soft tissue planes used by various authors (1) Soft tissue facial line; (2) Steiner’s S line; (3) E plane by Ricketts; and (4) Holdaway’s H line.

Holdaway’s analysis introduced the concept of the harmony line, or H line, which is drawn as a tangent to the chin and the upper lip. Holdaway’s analysis contains 11 measurements as follows ( Table 27.1 and Fig. 27.6 ):

• 1.

  Soft tissue facial angle : The soft tissue facial angle measures a line drawn from the soft tissue nasion (Na or n) to the soft tissue chin (Pog or pg) measured along the FHP. A measurement of 91 degrees is ideal, with an acceptable range of ±7 degrees. This measurement helps categorise whether a case is prognathic (>91 degrees) or retrognathic (<91 degrees). There is an extensive range of 7 degrees; therefore, it must be carefully correlated with other parameters.

• 2.

  Skeletal profile convexity : Skeletal profile convexity is a linear measurement from point A to Downs’ facial plane (N-pg). Although it is not a soft tissue measurement, it provides a good assessment of skeletal convexity in relation to the lip position. The ideal measurement ranges from 2 to +2 mm and provides a guideline for achieving the dental relationship needed for facial harmony.

• 3.

  Holdaway ’ s H angle : Holdaway’s H angle measures the H line to the soft tissue facial plane drawn at nasion and soft tissue pogion (Na-Pog). Measurements of 7–15 degrees are in the ideal range and are correlated with skeletal profile convexity. Ideally, as skeletal convexity increases, the H angle must also increase if a harmonious drape of soft tissues is to be realised in varying degrees of profile convexity. The H line signifies that as skeletal convexity increases, so does the convexity of the soft tissue profile if the entire facial complex is to be one of balance and harmony.

  • H angle measures the prominence of the upper lip in relation to the overall soft tissue profile. The H angle increases as we go from concave to convex skeletal patterns. Changes in the H angle reflect the direction of growth, especially of the mandible. The H angle changes during treatment or observation periods in the same patient and helps quantify differences between one patient and another.

• 4.

  Nose prominence : Nose prominence can be measured using a line perpendicular to the FHP and running tangent to the vermillion border of the upper lip. This measures the nose from its tip in front of the line and the depth of the incurvation of the upper lip to the line. Although the nasal form is judged on an individual basis, measurements less than 14 mm are considered small, while those above 24 mm are considered large.

• 5.

  Superior sulcus depth : Superior sulcus depth is measured as the distance between a line perpendicular to the FHP and tangent to the upper lip. A 1–4 mm range is acceptable, with 3 mm being ideal. During orthodontic treatment or surgical orthodontic procedures, efforts should be made to allow this measurement to be around 1.5 mm. Decreased values are suggestive of upper lip strain.

• 6.

  Soft tissue chin thickness : Soft tissue chin thickness is the horizontal distance between hard and soft tissue facial planes (N-Pg/n-Pog’). Average values are between 10 and 12 mm. In a very thick soft tissue chin, leaving the lower incisors in a more anterior position is best to provide much-needed lip support.

• 7.

  Upper lip thickness: Upper lip thickness is measured near the base of the alveolar process, at about 3 mm below point A. It is at a level just below the point at which nasal structures influence the drape of the upper lip. This measurement is useful when comparing the lip thickness overlying the incisor crowns at the level of the vermillion border and when determining the amount of lip strain or incompetency present as the patient closes his/her lips over protrusive teeth.

• 8.

  Upper lip strain : Upper lip strain is commonly seen on cephalograms of patients with proclined upper lips. In this situation, the patient habitually tries to close his/her lips to hide proclined teeth. In doing so, the average thickness of the upper lip is not recorded on the cephalogram. While taking the cephalogram, asking the patient to relax his/her lips by licking them and keeping them in repose is always advisable. When lip strain is present, strain measurement can be done horizontally from the vermillion border of the upper lip to the labial surface of the crown of the most proclined incisor.

  • The difference between the two measurements, if more than 1 mm, suggests lip strain. The usual lip thickness at the vermillion border is 13–14 mm. If this measurement is less than the thickness of the lip (beyond the acceptable range), then the lips are considered strained. The difference between the two measurements is called the strain factor.

  • It also reveals the amount of retraction needed to produce standard lip form and thickness. It is important to note that inherent lip thickness matters when predicting the response of the lips to retraction. Thick lips do not retract significantly. The ratio between a change of position of the upper lip and the linear retraction of maxillary incisors is usually 1:3.

  • When lip thickness at the vermillion border is larger than the average thickness measurement, this usually identifies a lack of vertical growth of the lower face with a deep overbite and resulting lip redundancy.

• 9.

  Upper lip sulcus depth : The upper lip sulcus depth is measured from the Sn to the H line. The ideal is 5 mm, with a 3–7 mm range. When the skeletal convexity of a patient is from −3 to 5 mm, the lips can usually be aligned nicely along the H line, especially when the superior sulcus measurement is at or near 5 mm. With short and thin lips, 3 mm will be adequate. In longer and thicker lips, 7 mm may give excellent balance. If this measurement is 8 or 9 mm with no evidence of lip strain or lack of harmony of facial lines, extracting premolars may not be necessary.

• 10.

  Lower lip to the H line : The lower lip to the H line is measured from the most prominent point on the outline of the lower lip. The ideal is 0–0.5 mm anterior to the H line, ranging from 1 mm behind to 2 mm in front of the H line. Lack of chin may be a factor when the lower lip appears very prominent. Sliding genioplasty surgical procedures can be very beneficial in some of these cases.

• 11.

  Inferior sulcus to the H line : The inferior sulcus to the H line is measured from the point of greatest incurvation between the vermillion border of the lower lip and the soft tissue chin to the H line. The contour in the inferior sulcus area should fall into harmonious lines with the superior sulcus.

TABLE 27.1

Summary of Holdaway’s variables, norms and interpretation

S.no.		Variable	Norm value	Interpretation
1	Soft tissue facial angle	Soft tissue nasion (Na or n) to the soft tissue chin (Pog or pg) measured along the Frankfurt horizontal plane (FHP).	91±7 degrees	Indicates soft tissue face prognathism.
2	Skeletal profile convexity	A point to Downs’ facial plane (N-pg).	2 to +2 mm	Indicates face skeletal prominence.
3	Holdaway’s H angle	Angle formed by H line to the soft tissue facial plane drawn at nasion and soft tissue pogion (Na-Pog).	7–15 degrees	As the skeletal convexity increases, the H angle must also increase in a harmonious face profile.
4	Nose prominence	Linear measurement using a line perpendicular to the FHP and running tangent to the vermillion border of the upper lip.	14–21 mm	Small: <14 mm Large: >24 mm
5	Superior sulcus depth	Superior sulcus depth is measured as the distance between a line perpendicular to the FHP and tangent to the upper lip.	1–4 mm 3 mm ideal	Decreased values suggest upper lip strain.
6	Soft tissue chin thickness	Soft tissue chin thickness is the horizontal distance between hard and soft tissue facial planes (N-Pg/n-Pog’).	10–12 mm	Excessive chin thickness may require support from lower incisors by their more anterior position.
7	Upper lip thickness	Upper lip thickness is measured near the base of the alveolar process, at about 3 mm below point A.	3 mm just below point A	Helps in interpreting lip strain.
8	Upper lip strain	Upper lip strain measurement is made horizontally from the vermillion border of the upper lip to the labial surface of the crown of the most proclined incisor.	The usual lip thickness at the vermillion border is 13–14 mm.	The difference between the two measurements, if more than 1 mm, suggests lip strain. a
9	Upper lip sulcus depth	The upper lip sulcus depth is measured from the Sn to the H line.	5 mm, range 3–7 mm	This measurement is used conjunction with skeletal convexity.
10	Lower lip to the H line	The lower lip to the H line is measured from the most prominent point on the outline of the lower lip.	The ideal is 0–0.5 mm, range −1 mm to 2 mm	Chin thickness will influence this measurement.
11	Inferior sulcus to the H line	It is measured from the point of greatest incurvation between the vermillion border of the lower lip and the soft tissue chin to the H line.	Qualitative observation	Upper and lower lip sulcus to be in coordination with H line.

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