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American Journal of ORTHODONTICS and DENTOFACIAL ORTHOPEDICS

Founded in 1915 Volume 103 Number 5 May 1993

Copyright �9 1993 by the American Association of Orthodontists

SPECIAL ARTICLE

Facial keys to orthodontic diagnosis and treatment planning--part H

G. William Arnett, DDS, ~ and Robert T. Bergman, DDS, MS b Santa Barbara, Calif.

This isPart II of a two-part article. Part I was published in the AMERICAN JOURNAL OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS, "VoI. 103, No. 4. Part I discussed the problem of accurate orthodontic diagnosis. Part I1 discusses the solution to the orthodontic diagnostic problem. (AM J ORTHOD DENTOFAC ORTHOP 1993;103:395-411 .)

N i n e t e e n facial traits were selected for this examination (Table I). Two views of the patient are used for identification of problems in three planes of space:

I. Frontal A. Relaxed lip B. Functional analysis

1. Closed lip 2. Smile

II. Profile A. Relaxed lip

FRONTAL VIEW

Natural head posture, centric relation, and relaxed lip posture are used to accurately assess the frontal view.

Outline form and symmetry (Fig. 1)

General outline form and asymmetries are noted. ' The widest dimension of the face is the zygomatic width

'Private Practice, Orthognathic Surgery; lecturer, orthognathic surgery at Uni- versity of California at Los Angeles and Loma Linda University; clinical in- structor, Orthognathic Surgery at University of California at Los Angeles and Valley Medical Center; attending staff at St. Francis llospital and Cottage Hospital, Santa Barbara. bln private orthodontic practice. Copyright �9 1993 by the American Association of Orthodontists. 0889-5406/93/Sl.00 + 0.10 811142808

Table I. Frontal and profile facial examination: the 19 facial traits included in the facial examination are listed

1. Frontal view A. Outline form B. Facial level C. Midline alignments D. Facial one-thirds E. Lower one-third evaluation

I. Upper and lower lip lengths 2. Incisor to relaxed upper lip 3. Interlabial gap 4. Closed lip position 5. Smile-lip level

II. Profile view A. Profile angle B. Nasolabial angle C. Maxillary sulcus contour D. Mandibular sulcus contour E. Orbital rim F. Cheekbone contour G. Nasal base-lip contour H. Nasal projection I. Throat length J. Subnasale-pogonion line

(Fig. 1). The bigonial width is approximately 30% less than the bizygomatie dimension. Farkas ''2 has established normal values for height and width. Tile height to width proportion is 1.3:1 for females and 1.35:1 for

395

396 Arnett and Bergman American Journal of Orthodontics and Dentofacial Orthopedics May 1993

Go ~

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Fig. 1. Facial height: Hairline (H) to soft tissue menton (Me').. Facial widths: Zygomatic arch (ZA) to zygomatic arch (ZA),. Gonion (Go') to gonion (Go').

males. An alternative to measuring height and widtiJ is to artistically describe the face. Faces are wide or narrow, short or long, round or oval, square or rectangular.

The important question when assessing these di- mensions is: Will orthodontic and/or surgical care necessary for bite correction correct or accentuate existing height and width imbalance? An example of orthodontic correction of height-width imbalance is the use of bite opening mechanics to lengthen the face during bite cor- rec t io~ An example of surgical correction is maxillary impaction to shorten the long face.

The extremes of disproportion are short and wide or long and narrow. Short, square facial outlines are indicative of deep bite Class II malocclusion, vertical maxillary deficiency, and in some cases, masseteric hyperplasia. Long, narrow faces are associated with vertical maxillary excess or mandibular protrusion with dental interferences leading to open bite. The bizygomatic dimension is often deficient (cheekbone deficiency) in combination with maxillary retrusion. The bigonial dimension may be deficient in combination with mandibular retrusion.

Height and width disproportion is corrected in two ways:

1.

.

Maxillary or mandibular surgery is used simultaneously to correct the bite and to lengthen or shorten the facial height. "'- Augmentation or reduction of the facial height or width.

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Fig. 2. Pupil plane (PP) is horizontal line drawn through pupils. This line is usually parallel to the horizon and is referred to as frontal postural horizontal. Upper dental arch (UDA) level is a line formed through the left and right maxillary canine tips. Lower dental arch (LDA) level is a line formed through the left and right mandibular canine tips. Chin-jaw line (CJL) is assessed by a line drawn on the under surface of the chin at maximum iissue contact. All four lines should be parallel to each ether.

Examples of the latter are chin lengthening to increase facial height (H to Me'), cheekbone augmentation to increase the bizygomatic width (Zy to Zy), or augmentation of the mandibular angles to increase the bigonial dimension (Go' to Go'). Buccal lipectomies can help reduce excessive width in the submalar cheek areas.

As a general rule, the maxilla should rarely be moved up and back. This movement decreases lip support, increases the nasolabial folds, decreases incisor exposure, and can make the facial outline appear short and wide. These changes give the appearance of premature facial aging.

The most common to least common sites of facial asymmetry are chin, mandibular angles, and cheek~ bones. The maxilla is rarely in skeletal asymmetry. Asymmetries can occur with any growth abnormality but are strongly associated with unilateral condylar hyperplasia.

Correction of asymmetries are accomplished with (1) cant correction or midline movement of the maxilla and mandible simultaneous with occlusal correction or (2) augmentation dr reduction of the skeletal surfaces. Examples of the latter include unilateral cheekbone,

American Journal of Orthodontics and Dentofacial Orthopedics Arnelt and Berg/nan 397 Volume 103. No. 5

Fig. 3. Constructed horizontal reference line is formed by drawing line through pupil area parallel to floor. This line is used when the pupil plane is not parallel to the floor (eyes are not level) when the head is in frontal postural horizontal.

angle, or body augmentation. A common asymmetry correction is chin shifting to the right or left to center the chin on the facial midline.

Facial level (Fig. 2)

To examine facial levels a rel iable horizontal land- mark line is necessary. With the patient in natural head posture, 3 the pupils are assessed for level with the horizon. If the pupils are level, they are used as the horizontal reference line and adjacent structures are measured relative to this line (Fig. 2). Structures compared with the pupil line are (1) upper canine level, (2) lower canine level, and (3) chin and jaw level.

Mandibular deviations commonly have upper and lower occlusal cants with chin and jaw line canting associated. Deviations from level should be noted and correction integrated into the overall bite treatment plan. If bimaxillary surgery is contemplated, occlusal cant is corrected routinely at surgery. If one jaw surgery is contemplated, the occlusal cant can be neglected unless it is esthetically problematic. When problematic, either orthodontic tooth movement or bimaxillary surgery must be used to correct the cant.

If the pupils, in natural head posture, are not level to the horizon, a constructed frontal horizontal reference line is used (Fig. 3). This line is visualized as follows:

I. Frontal natural head posture.

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Fig. 4. Important midline structures are assessed. Nasal bridge (NB), nasal tip (NT), filtrurrt (F), upper incisor midline (UIM), lower incisor midline (LIM), and chin midline point (Me') should be on a line that is perpendicular to the frontal postural horizontal. Filtrum is usually the least asymmetric of these points and is therefore generally used as a starting point for midline structure assessment. All midline points may not line up. The dental midlines and chin should be placed to integrate with other midlines (most importantly the filtrum center).

2. Horizontal line parallel to the horizon through the pupil area.

3. Assess other structures relative to this line (Fig. 3).

Midline alignments (Fig. 4)

Midlines are assessed with uppermost condyle position and first tooth contact. If occlusai slides alter joint position, no reliable midline assessment can be made. The relative positions of soft tissue landmarks (nasal bridge, nasal tip, filtrum, chin point) and dental midline landmarks (upper incisor midline, lower incisor midline) are noted. Needed changes are incorporated into the surgical/orthodontic treatment plan to position these structures on the vertical midline of the face. Filtrum is usually a reliable midline'structure and can be used as the basis for midline assessment most often. When the pupils are level in natural head posture, a vertical line through filtrum midpoint is used to assess

. .other hard and soft tissue midline structures (Fig. 4). If the pupils are not level, a vertical line through filtrum midpoint, perpendicular to postural horizontal, is used to assess midline structures (Fig. 5). With the evalu-

398 Arnett a/zd Bergman American Journal of Orthodontics and Dentofacial Orthopedics May 1993

Constructed Posaa-al Horizontal

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Fig. 5. When pupils are not level, constructed horizontal reference line (Fig. 3) is used. A perpendicular to the constructed horizontal line through filtrum is used to assess other midline structures.

1/3

,_7 Middle 1/3

Me I

Fig. 6. Face is .divided into thirds by drawing lines through hairline (H), midbrow (Mb), subnasale (Sn), and soft tissue menton (Me').

ation of skeletal or dental midlines, etiologic factors are assigned.

Dental midline shifts are the result of multiple dental factors including:

1. Spaces 2. Tooth rotations 3. Missing teeth 4. Buccally or lingually positioned teeth 5. Crowns or fillings which change tooth mass 6. Congenital tooth mass difference from left to

right

Model examination is used to distinguish dental midline shift etiologic factors (spaces, rotations). Den- tal midline shifts are treated orthodontically. Asym- metric premolar extractions may be necessary to align dental and skeletal midlines. Skeletal midline shifts are not corrected orthodontically, surgery is employed. When the dental and skeletal midlines deviate together, the etiologic factor is usually skeletal, and surgery is used to correct (i.e., chin and lower incisor midline are 3 mm to the left). Stability, periodontal health, and facial balance are optimized when dental shifts the result of skeletal deviation are treated with surgical, rather- than orthodontic, tooth movement. Attempts to orth-

odontically correct the bite when the etiologic factor is skeletal can produce buccal plate violation and gingival recession.4'~

Facial one thirds (Fig. 6)

The face divides vertically into thirds from hairline to midbrow, midbrow to subnasale, and subnasale to soft tissue menton (Fig. 6). The thirds are within a range of 55 to 65 mm, vertically.' The hairline is vari- able, and the upper third is frequently low range. In- creased lower one-third height is frequently found with vertical maxillary excess and Class III malocclusions (lack of interdigitation opens vertical height). De- creased lower one-third height is associated with vertical maxillary deficiency and mandibular retrusion deep bites. Production of correct proportion influences the choice of surgical procedure used to correct the occlusion (i.e., maxillary impaction to correct Class II malocclusion associated with long lower one-third rather than mandibular advancement). The equality of the middle and the lower thirds should not be used as the determining factor in facial height changes. The appearance of the landmarks (incisor exposure, interlabial gap) within the lower third are more important in assessing balance than are the equality of the middle and the lower thirds.

American Journal of Orthodontics and Dentofitcial Orthopedics Arnett and Berg/nan 309 Vohtme 103, No. 5

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Upper Lip Length

F , . , / I i Lower Lip Length

Me'

Fig. 7. With lips relaxed, lower third is subdivided by drawing lines through subnasale (Sn), upper lip inferior (ULI), lower lip superior (LLS), and soft tissue menton (Me'). The upper lip is half the length of the lower.

Lower one-third evaluation (Figs. 7 through 9)

This area of facial analysis is extremely important in surgical orthodontic diagnosis and treatment planning. The importance of relaxed lip position for these measurements cannot be overemphasized.

Upper and lower lip lengths (Fig. 7). The lips are measured independently in a relaxed position (Fig. 7). The normal length from subnasale to upper lip inferior is 19 to 22 mm. x If the upper lip is anatomically short (18 mm or less), an increased interlabial gap and incisor exposure is seen with a normal lower face height. This should not be confused with vertical maxillary excess (increased interlabial gap, increased upper incisor exposure, increased lower one-third facial height).

The lower lip is measured from lower lip superior to soft tissue menton and normally measures in a range of 38 to 44 mm. ~ Anatomic short lower lip is sometimes associated with Class II malocclusion and is verified by cephalometric measurement of the lower anterior dental height (lower incisor tip to hard tigsue menton; women, 40 mm + 2 mm, and men, 44 mm - 2 mm).6 Anatomic short lower lip should not be confused with a short lower lip secondary to posture (upper incisor interferences) seen in Class II deep bite cases with normal anterior dental height. Anatomic short lower lip can be lengthened with a lengthening genioplasty.

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UTTL

Fig. 8. Incisor exposure is measured with lips relaxed from upper lip inferior (ULI) to maxillary incisor edge (MxlE). The upper tooth to lip (UTTL) is the vertical dimension of the incisor exposed between ULI and MxlE.

Anatomic long lower lip can be associated with Class III malocclusions. This should be verified with the cephalometric anterior dental height measurement. A closed lip position will produce a long lower lip in combination with increased lower facial height (vertical maxillary excess and Class II1) as the lip elongates to close. The closed lip length is misleading and should not be used for treatment planning. The normal ratio of upper to lower lip is 1:2. j Proportionate lips har- monize regardless of length; disproportionate lips may need length modification to appear in balance. Lip measurements identify normal or abnormal soft tissue length that can be related to dentoskeletal length normalcy, excess, or deficiency.

Lip redundancy is seen in cases of vertical maxillary deficiency and mandibular retrusion with deep bite and, rarely, long lip lengths. To accurately assess lip lengths with redundant lips, the patient 's bite must be opened until the lips separate (Figs. 7). ~ This is best accomplished with a pink base plate wax bite used to open the bite on centric relation (no translation), t The face is examined in that posture, and vertical skeletal increases are planned.

Upper tooth to lip relationship (Fig. 8). The distance from upper lip inferior to maxillary incisal edge is measured (Fig. 8). The normal range is 1 to 5 mm.t Women show more within this range. Surgical and orthodontic vertical changes are based primarily on this measurement (i.e., postsurgical incisor exposure range o f l t o 5 m m ) .

Conditions of disharmony are produced by four variables:

1. Increased or decreased anatomic upper lip length (infrequently).

2. Increased or decreased maxillary skeletal length (frequently).

400 Arnett and Bergman American Journal of Orthodontics and Dentofacial Orthopedics May 1993

r .} Interlabial Gap

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Fig. 9. Interlabial gap is measured in relaxed lip position from upper lip inferior (ULI) to lower lip superior (LLS).

3. Thick upper lips expose less incisor than thin upper lips, all other factors being equal.

4. The angle of view changes the amount of incisor visible to the viewer. The three variables that contribute to the angle of view are (1) the patient's height, (2) the observer's height, and (3) the distance from the facial surface of the upper lip to the incisive edge (increased lip thickness reveals less relative tooth exposure).

Overimpaction of upper incisor teeth leads to the appearance of premature aging, especially in conjunc- tion with maxillary retraction. This type of surgical movement is rarely indicated. Posterior movement of the maxillary incisors is indicated only for true maxillary protrusion. Orthodontic overretraction, which is used to occlusally correct mandibular retrusion, produces premature aging of the face.

lnterlabial gap (Fig. 9). With the lips relaxed, a space of 1 to 5 mm ~ between upper lip inferior and lower lip superior is present (Fig. 9). Females show a larger gap within the normal range." This measurement is also dependent on lip lengths and vertical dentoskeletal height.

Increases in interlabial gap are seen with anatomic short upper lip, vertical maxillary excess, and mandibular protrusion with open bite secondary to cusp interferences. Decreased interlabial gap is found with vertical maxillary deficiency, anatomically long upper lip

(natural change with aging, especially in males), and mandibular retrusion with deep bite. Abnormalities should be considered when planning skeletal changes. An anatomically short upper lip should be recognized as a soft tissue problem and should not be treated by excessively shortening the maxilla. This can lead to a short, round facial outline.

Closed lip position. Even though an understanding of relaxed lip position is essential, an understanding of closed lip position adds support to diagnostic patterns. The closed lip position also reveals disharmony between skeletal and soft tissue lengths.

Increased mentalis contraction (mentalis strain), lip strain, and alar base narrowing are observed in vertical skeletal excess, anatomic short upper lip and some cases of mandibular protrusion with open bite.

Lip redundancy is seen with vertical maxillary deficiency and mandibular retrusion with deep bite. With balanced lip and skeletal lengths, the lips should ideally close from a relaxed, separated position without lip, mentalis, or alar base strain. The maxilla should not be impacted to idealize the short upper lip closure unless the facial outline will tolerate such a change.

Smile positidn lip level. When examining the smile posture, different lip elevations are observed in normal and abnormal skeletal patterns. Ideal exposure with smile is three-quarters of the crown height to 2 mm of gingiva, females more than males.~ Variability in gingival exposure is related to (I) lip length, (2) vertical maxillary length, (3) maxillary anatomic crown length, and (4) magnitude of lip elevation with smile.

Excess gingival exposure may be caused by a short upper lip, vertical maxillary excess, short clinical crown, and/or large lip elevation with smiling. Because of etiologic variability, surgical shortening of the maxilla is indicated only when excess gingival exposure is found in combination with increased interlabial gap, increased tooth exposure, increased lower face height, and/or mentalis strain.

Deficient exposure etiologic factors include a long upper lip, vertical maxillary deficiency, and/or minimal smile lip elevation. Decreased incisor exposure is treated with maxillary lengthening when found in combination with decreased interlabial gap-lip redundancy, short lower one-third face height, and normal upper lip length.

When impacting or lengthening the maxilla on the basis of reposed incisor exposure, gingival smile exposure should also be considered. For example, if the patient has normal smile gingival exposure (1 to 2 mm) and the incisors are lengthened to treat decreased relaxed lip incisor exposure, excessive smile gingival exposure will result.

Particular care should be taken with short clinical

American Journal of Orthodontics and Dentofacial Orthopedics Arnetl and Bergman 401 Volume 103, No. 5

G,

Sn

Fig. 10. Profile angle is measured by connecting points glabella (G'), subnasale (Sn), and soft tissue pogonion (Pg'). The angle is measured on the left hand side with the patient facing right.

Fig. 11. Nasolabial angle is developed by connecting columella line (inferior nasal septum) (C), subnasaTe (Sn), and upper lip anterior point (ULA).

crowns. A 3 to 4 mm repose incisor exposure may expose unacceptable amounts of gingiva when smiling because of short maxillary incisor crowns. This situa- tion is properly treated by placing normal length crowns (veneers) on the maxillary incisors and treatment planning from the repose and smile perspective. The "gingival smile" is never treated to ideal at the expense of underexposing the incisors in the relaxed lip position.

PROFILE VIEW

Natural head posture, centric relation, and relaxed lips are used to accurately assess profile.'

Profile angle (Fig. 10)

This angle is formed by connecting soft tissue gla- belle, subnasale, and soft tissue pogonion'(Fig. 10). 7.8 General harmony of the forehead, midface, and lower face is appraised with this angle. Maxillary and mandibular basal bone anteroposterior discrepancies are easily visualized. Class I occlusion presents a total facial angle range of 165 ~ to 175~ ' Class II angles are less than 165 ~ and Class III are greater than 175 ~ Skeletal discrepancies producing Class II angulation

include maxillary protrusion (rare), vertical maxillary excess (common), and mandibular retrusion (common). Class III skeletal patterns include maxillary retrusion (common), vertical maxillary deficiency (rare), and mandibular protrusion (common).

Surgical procedures should generally address the cosmetic imbalance established with this angle. The profile angle is the most important key to the need for anteroposterior surgical correction. When values are less than 165 ~ or greater than 175 ~ skeletal malocclusions needing surgery are probably the cause. Angles at the extreme of normal (greater than 175 ~ or less than 165 ~ ) are usually caused by skeletal disharmony. Soft tissue thickness differences are not capable of causing these extreme angle changes.

Nasolablal angle (Fig. 11)

This angle is formed by the intersection of the upper lip anterior and columella at subnasale (Fig. 11). This angle can change noticeably with orthodontic and surgical procedures that alter the anteroposterior position or inclination of the maxillary anterior teeth. 9I' All procedures should place this angle in the cosmetically

402 A rnetl altd Hergma/z American Journal of Orthodontics and Dentofacial Orthopedics May 1993

MxSC

Fig. 12. Maxillary sulcus contour (MxSC) is subjectively assessed. The contour is described as either accentuated, gentle curve (normal) or flat. Measurement of this contour is impractical.

desirable range of 85 ~ to 105~ I Female patients will usually be more obtuse within this range. Factors to be considered in treatment planning to correctly achieve this angle are as follows:

I. Existing angle. 2. Tilting versus bodily movement of maxillary

teeth (orthodontic and surgical) and predicted effect on the existing lip position.

3. Estimation of lip tension present. Tense lips may move more posteriorly with tooth and basal bone movement and less anteriorly. Flaccid lips may move less with posterior tooth and basal bone movement and less with anterior.'-""

4. Anteroposterior lip thickness. Thin lips (6 to 10 ram) 9"12"~3 may move more with tooth retraction movement than thick lips (12 to 20 mm). I-''~4

5. The magnitude of the mandibular retrusion (overjet). The larger the overjet distance, the more retraction of the maxillary incisors will be necessary, thus opening the nasolabial angle..gL 'z

6. The following factors affect the anteroposterior movement of incisor teeth after extractions: Amount of anterior crowding, spaces, tooth

mass proportion (upper versus lower), posterior rotations, curve of Spee (upper versus lower), and anchorage (headgear, Class II elastics).

7. Extraction versus nonextraction. 8. Extraction pattern (first versus second pre-

molars).

If the nasolabial angle is open (approximately,105~ retraction of anterior teeth orthodontically and surgically should be avoided in treatment planning. Like- wise, a long nose will become adversely prominent with lip retraction. Present limited knowledge of how lips respond to anteroposterior movement of the teeth dictates a conservative approach when large movements are contemplated. Crowding dictates the need for extraction, facial balance influences which teeth are ex- tracted and how spaces are closed.

Surgical movement of the maxilla also affects the nasolabial angle. The same factors that affect orthodontic change should be analyzed when considering maxillary movement. As a general rule, the maxi l la should not be moved posteriorly in treating dentofacial deformities, especially in combination with superior repositioning. This creates nasal elongation, alar base depression, and opening of the nasolabial angle, all of which create facial premature aging. Inadvertent maxillary retraction occurs with isolated LeFort surgery when the VTO x-ray film is taken with the condyles on the eminence rather than seated in the fossa.

Maxillary sulcus contour (Fig. 12)

Normally this sulcus is gently curved 15 and gives information regarding upper lip tension (Fig. 12). With lip tension, the sulcus contour flattens. Flaccid lips form an accentuated curve with the vermilion lip area show- ing an accentuation of curve. ,2 The flaccid lip generally is thick (12 to 20 mm from anterior vermilion to labial incisor) giving the lip (i.e., headgear with Class II elastics or functional appliance treatment) the appearance of beingtoo far forward relative to the teeth. '2 The maxilla should not be retracted significantly when a deeply curved, thick lip is present since this produces poor lip support and cosmetics. If possible, the maxilla should be moved forward into a thick, curved lip to improve lip support.

Mandibular sulcus contour (Fig. 13)

This contour is a gentle curve '~ (Fig. 13) and can indicate lip tension. When deeply curved, the lower lip is flaccid in character (Class I1, vertical maxillar3/deficiency). The deep curve is usually secondary to maxillary incisor impingement in the case of deep bite Class II and vertical maxillary deficiency. When flattened, the lower lip demonstrates tension of tissues (Class I11).

American Journal of Orthodontics and Dentofacial Orthopedics Arnett and Bergman 403 Volume 103, No. 5

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M~SC

Fig. 13. Mandibular sulcus contour (MdSC) is subjectively assessed. The contour is either accentuated, gentle curve (normal) or flat. Measurement of this contour is impractical.

Fig. 14. Orbital rim projection is measured from the anterior most globe (Gb) to the orbital rim point (OR). A subjective orbital rim description is also given: Normal, flat, or protruded.

Surgical procedures that correct the basal bone generally will improve the mandibular sulcus angle (i.e., deep contour associated with deep bite Class II malocclusion or flatness associated with mandibular protrusion).

Orbital rim(Fig. 14)

The orbital rim is an anteroposterior indicator of maxillary position. Deficient orbital rims may correlate positionally with a retruded maxillary position because the osseous structures are often deficient as groups, rather than in isolation. The globe normally is positioned 2 to 4 mm anterior to the orbital rim (Fig. 14). t The surgical maxillary versus mandibular decision is influenced by the orbital rim position. Deficient orbital rims dictate maxillary advancement, all other factors being equal.

Cheekbone contour (Figs. 15 and 16)

Cheekbone assessment requires frontal and profile examination simultaneously (Figs. 15 and 16). Cheek- bone contour (CC) correlates with maxillary anteroposterior position, frequently the cheekbone contour is

deficient in combination with maxillary retrusion. De- ficient cheekbones may correlate positionally with a retruded maxillary position because the osseous structures are often deficient as groups, rather than in isolation. Cheekbone contour is used as one of the main indicators of maxillary retrusion. This area should have an apex at the cheekbone point (CP) and not appear fiat. The CP is located 20 to 25 mm inferior and 5 to 10 mm anterior to the outer canthus (OC) of the eye when viewed in profile (Fig. 15). When viewed frontally the CP is 20 to 25 mm inferior and 5 to 10 mm lateral to the OC (Fig. 16). It should be noted that true mandibular prognathism can show mild malar flatness as a relative observation to the extreme chin protrusion. True maxillary hypoplasia often is associated with true malar deficiency.

Nasal base-lip contour (Figs. 15 and 16)

The nasal base-lip contour (Nb-LC) line requires -'-frontal and profile examination simultaneously (Figs.

15 and 16). The line is the continuation of the cheekbone contour line. This area is an indicator of maxillary and mandibular skeletal anteroposterior position. Nor-

4 0 4 Arlzell atzd Bergman American Jot*rnal of Orthodontics and Dentofacial Orthopedics May 1993

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Figs. 15 and 16. Cheekbone contour is anteriorly facing, curved line that starts just anterior to ear, extending forward through cheekbone point (CP), then extending anteridr-inferiorly ending at maxilla point (MxP) adjacent to alar base of nose. F.or descriptive purposes the cheekbone contour is divided into three areas: (1) zygomatic arch, (2) middle contour area, and (3) subpupil areas. These three areas, when taken together, constitute the cheekbone contour. Reconstruction of cheekbone contour, when deficient, should analyze all three parts separately in terms of correction. CP and MxP indicates osseous cheekbone and maxillary base positions, respectively. The nasal base-lip contour (Nb-LC) extends inferiorly from the maxilla point (MxP) as a gentle, anteriorly facing curve, ending just below and lateral to the mouth commissure. In normoskeletal patients the cheekbone-nasal base-lip contour complex is a smooth continuation, anteriorly facing, curved line. This line, when viewed frontally or from the side, is a definite flowing curve with no interruptions which are apparent with skeletal deformities.

Maxillary Retrusion mal position is indicated by the maxilla point (MxP) directly behind the alar base. The MxP is the most anterior point on the continuum of the cheekbone-nasal- lip contour and is an indication of maxillary anteroposterior position.

Maxillary retrusion is indicated by a straight or concave contour at MxP (Fig. 17). When this anatomic area is concave or fiat, maxillary advancement is necessary.

Mandibular protrusion interrupts the nasal base-lip line in the length of the upper lip (Fig. 18). When the line is interrupted within the height of the upper lip a mandibular setback may be indicated.

Nasal projection (Fig. 19)

The nasal projection (NP) measured horizontally from subnasale to nasal tip is normally 16 to 20 mm

Fig. 17. Maxillary retrusion: Cheekbone-nasal base-lip curve is interrupted at MxP.

American Journal of Orthodontics and Dentofacial Orthopedics Arnelt and Bergnlan 405 Volume 103, No. 5

Mandibular Protrusion

Fig. 18. Mandibular protrusion: Cheekbone-nasal base-lip curve is interrupted in upper lip area.

(Fig. 19).' Nasal projection is an indicator of maxillary anteroposterior position. This length becomes particu- larly important when contemplating anterior movement of the maxilla. Decreased nasal projection contraindi- cates maxillary advancement. With a Class III malocclusion, short nose, and all other factors equal,�9 mandibular setback is indicated.

Throat length and contour (Fig. 20)

The distance from the neck-throat junct ion to the soft tissue menton should be noted (Fig. 20). No mil- limeter measurement is necessary, but a planned mandibular setback will change this length. The predicted esthetic result should produce a normal appearing length without sagging. A patient with a short, sagging throat length is not a good candidate for mandibular setback. A long, straight throat length is amenable to mandibular setback. Often a mandibular setback is necessary with chin augmentation to balance lips with chin and main- tain throat length. Suction lipectomy is a useful adjunct for controlling submental sag with setbacks or when isolated fat accumulation is present.

Subnasale-pogonion line (Sn-Pg') (Fig. 21)

Burstone reported that the upper lip is in front of the Sn-Pg' line by 3.5 mm • 1.4 mm, and the lower lip is in front of the line by 2.2 mm --- 1.6 mm. 16

The relationship of the lips to the Sn-Pg' line is an important aid in orthodontic soft tissue analysis and treatment. Tooth movement changes the relationship of the lips to the Sn-Pg' line and therefore the esthetic

NP

NT

Fig. 19. Nasal projection (NP) is measured from subnasale (Sn) to nasal tip (NT). The lines through Sn and NT are perpendicular to the floor when the head is in a natural postural position.

Fig. 20. Throat length (TL) is assessed from neck-throat point (NTP) to soft tissue menton "(Me'). This distance is subjectively described as either normal, long or short length, and with or without sag.

406 Arnett and Bergman American Journal of Orthodontics and Demofacial Orthopedics May 1993

Sn

Fig. 21. Subnasale-pogonion reference line is generated through points subnasale (Sn) and soft tissue pogonion (Pg'). Lip projections are evaluated relative to this line.

result. All tooth movements should be assessed in regard to the anticipated lip change to the Sn-Pg' line. Extractions should be avoided when they move the teeth and create retraction of the lips (dished-in) behind this line (Fig. 22). On the other hand, if unravelling the crowding with extractions allows for lip balance to the Sn-Pg' line, the extractions are esthetically acceptable.

The relationship of the lips to this line is affected by the following factors:

1. Skeletal relationship: When anterior or posterior skeletal disharmony exists, producing overjet abnormalities (positive or negative), the Sn-Pg' has no validity.

2. Incisor inclinations: With a Class I skeletal pattern, the upper and lower incisors must be at proper overjet and axial inclination to produce proper protrusion of the lips relative to the Sn- Pg' line.

3. Lip thickness: The lip relationship to the Sn-Pg' line is dependent on lip thickness. The Burstone relationship t6 is true only if the lips are the same thickness, all other factors being ideal. Class I incisors (upper incisor in front of lower incisor) produce Class I lips (upper lip in front of lower lip) only if the lips are of equal thickness.

This line is also used when planning surgery on the VTO (Fig. 23). The Sn-Pg' line is ideally drawn to the

lips through subnasale. If Pg' is significantly posterior to the line, a chin augmentation is indicated. Female chins are softer relative to this line.

SOFT TISSUE CHARACTERISTICS OF COMMON SKELETAL DEFORMITIES

With the 19 facial keys, 8 pure skeletal deformities with predictable soft tissue appearances can be defined. The greater magnitude of the skeletal deformity the more distinct the soft tissue pattern. Skeletal deformities may occur hz combination (i.e., vertical maxillary excess with mandibular prognathism) and facial traits are therefore blended. In all cases, facial traits are helpful in diagnosing skeletal problems. The eight uncombined or pure or unmixed anteroposterior facial-skeletal types are as follows:

A. Class I facial and dental (facial angle Class l) (Fig. 24) 1. Vertical maxillary excess (Table lI) 2. Vertical maxillary deficiency (Table III)

B. Class II facial and dental (facial angle Class II) (Fig. 25) 3. Maxillary protrusion (Table IV) 4. Vertical maxillary excess (Table II) 5. Mandibular retrusion (Table V)

C. Class III facial and dental (facial angle Class III) (Fig. 26) 6. Maxillary retrusion (Table VI) 7. Vertical maxillary deficiency (Table Ill) 8. Mandibular protrusion (Table VII)

Knowing the eight unmixed skeletal patterns is helpful in organizing facial analysis information into a co- hesive, meaningful whole. Without facial analysis, dis- tinguishing the skeletal source of the malocclusion can be difficult. Facial trait identification and categorization leads to a differential diagnosis of skeletal patterns (Table VIII Class II, Table IX Class Ill). Cephalometric analysis has been shown to be ineffective in this regard. The advantage of a diagnosis based on facial traits is important. Skeletal malocclusions have profound soft tissue imbalance that patients expect to be corrected. Facial based treatment planning ensures that facial change will be correct, whereas cephalometrics have been shown to he unreliable.

ORTHODONTIC PREPARATION FOR SURGERY

Facial and dental discrepancies may not be proportionate because of dental compensations to the anteroposterior skeletal malalignment. ~7 Dental compensations are incisor axial inclination changes in response to increased or decreased overjet. Mandibular retrusion and, occasionally, vertical maxillary excess are associated with lower incisor flaring and upper incisor up-

American Journal of OrthtMontics and Dente~acial Orthopedics Arne t t and Bergman 407 Volume 103, No. 5

' / A :'

~'~'Sn

Fig. 22. A, Normal lip relationship to Sn-Pg' line. B, Premature aging associated with premolar extractions and incisor retraction. The lips fall on or behind the Sn.~Pg' line giving the "dished-in" orthodontic appearance. The nasolabial angle may also open to unacceptable ranges.

righting. Mandibular protrusion, maxillary retrusion and vertical maxillary deficiency are associated ~vith upper incisor flaring and lower incisor uprighting.

Extraction patterns and mechanics are aimed at re- moving dental compensations.before surgery. Compen- sation removal leads to better facial results. An example of this is a 10 mm skeletal mandibular retrusion. Incisor dental compensations to the overjet may decrease the 10 mm overjet to 5 ram. If the mandible is advanced with the compensations present, the chin deficiency is still 5 mm. In contrast, when dental compensations are removed, the 10 mm overjet and 10 mm chin retrusion are simultaneously and totally corrected with surgical advancement.

Inappropriate orthodontic preparation (e.g., upper first premolar extractions, headgear and Class II elastics to treat a skeletal mandibular retrusion) distorts the equality of the dental and facial problems far more than dental compensations. In an attempt to correct the bite without surgery, the dental discrepancy becomes much less than the facial discrepancy magnitude. Subse- quently, if surgery is used for dental correction, the soft tissue problem is only minimally corrected. This problem leads to the conclusion that surgery should be planned from the beginning to obtain optimal facial changes with bite correction.'7"~ Extractions should be planned around factors including, most importantly, crowding, periodontal needs, and facial implications. Generally, extraction patterns decrease dental compen- sation to the incisor overjet problem.

The most common appropriate extractions for rou- tine facial-skeletal deformities are as follows:

r S n

Ideal

t pg' lk Needed Chl.e Augmmtatloe

Fig. 23. Sn-Pg' line is frequently used to surgically assess chin- lip-nasal base balance. With the v-ro occlusion in Class I, the line is oriented from Sn through ideal lip position. If Pg' falls on the chin, balance of chin-lip-nasal base is ideal. If Pg' falls behind the line, a chin advancement is necessary to obtain balance.

A. Class 1 facial and dental (chin in balance with the face) 1. Vertical maxillary excessIvar iable 2. Vertical maxillary deficiencyIvariable

American Journal of Orthodontics and Dentofaeial Orthopedics 408 Arnett and Bergman May 1993

CLASS I's

Oe ien

Fig, 24. Class I occlusion and chin projection can occur in combination with vertical maxillary excess or vertical maxillary deficiency. The anteropOsterior profile is normal, but the vertical height of the face is long or short.

Table II. Vertical maxil lary excess: common facial characteristics o f vertical maxil lary excess are listed

Vertical maxillary excess

Increased lower one-third Increased interlabial gap Increased incisor exposure Increased gingival smile Mentalis strain Decreased total profile angle* Accentuated mandibular sulcus contour Decreased throat length Normal nasal projection Normal nasotabial angle

*Class I VME can have a normal total facial angle.

B. Class II facial and dental (chin retruded) 1. Maxil lary p r o t r u s i o n - - l o w e r second and /o r

upper first premolars, orthodontic correction. No surgery required.

2. Vertical maxil lary e x c e s s - - u p p e r extraction based on extent and location o f crowding, lower extraction based on effects on upper lip support when LeFort I is done to correct vertical maxil lary excess.

3. Mandibular r e t r u s i o n - - u p p e r second premolar and /o r lower first premolars . . . . .

C. Class III facial and dental (chin protruded)

4 '

Table Ill. Vertical maxil lary deficiency: common facial characteristics o f vertical maxil lary deficiency are listed

Vertical maxillary deficiency

Decreased lower one-third Decreased interlabial gap Decreased incisor exposure Decreased incisor exposure with smile Lip redundancy Straight to Class Ill profile angle* Accentuated mandibular sulcus contour Normal nasal projection Normal to decreased nasolabial angle Increased throat length Normal cheekbones, alar base

*Class I VMD can have a normal total facial angle.

1, Maxil lary r e t r u s i o n - - u p p e r first and lower second premolars

2. Vertical maxil lary de f i c i e nc y - -uppe r first and lower second premolars

3. Mandibular p ro t ru s ion - -uppe r first and lower second premolars

An additional benefit of the surgical extraction pattern is that the anticipated surgical relapse becomes the opposite o f the orthodontic relapse pattern. An example of this is mandibular advancement with lower first pre-

American Journal of Orthtxlontics and Dentofacia/ Orthopedics Arnell and Bergman 409 Volume 103, No. 5

Class II's

-<~

/

Exce~

Fig. 25. Class II bite and chin projection can be produced by entirely different skeletal patterns. Maxillary protrusion, mandibular retrusion and vertical maxillary excess all can produce identical bites with similar chin profiles. The a r r o w s indicate the skeletal abnormality responsible for the bite and profile disharmony.

Class III's

(.

V ~ l l a r y Deficienc'~

Fig. 26. Class III bite and chin projection can be produced by entirely different skeletal patterns. Maxillary retrusion, mandibular protrusion, and vertical maxillary deficiency all can demonstrate identical Class III bite and similar profile characteristics. The a r r o w s indicate the skeletal abnormality responsible for bite and facial profile disharmony.

molar extractions that have uprighted the lower incisors. Surgical relapse is posterior, and orthodontic relapse at the lower incisors is anterior, in the opposite direction. The orthodontic relapse is a mechanism to compensate for surgical relapse.

CONCLUSION

Orthodontists use dental and facial keys to diagnose and to treat malocclusions. Dental keys include overjet, c~fiine occlusion, and molar occlusion. The dental keys are given much weight in the determination of treat-

410 Arnett and Bergman

Table IV. Maxi l la ry protrusion: c o m m o n facial

characterist ics o f maxi l lary protrusion are listed

Marillary protrusion*

Normal lower one-third Normal interlabial gap Normal incisor exposure Normal smile Decreased profile angle Normal mandibular sulcus contour Normal throat length Normal to short nasal projection Decreased nasolabial angle

*Skeletal maxillary protrusion is rare.

Table V. Mandibular retrusion: c o m m o n facial

characterist ics o f mandibula r retrusion

are listed

Mandibular retrusion

Decreased or normal lower one-third Decreased or normal interlabial gap Normal incisor exposure Normal smile Normal-to-lip redundancy Decreased profile angle Accentuated mandibular sulcus contour Decreased throat length Normal nasolabial angle Normal nasal projection

merit. Facial keys are not used by some orthodontists

and spar ingly by others. Typical ly , facial keys used by

orthodontists include the relat ive posi t ions o f the upper

lip, lower lip, and chin. These g ive informat ion, but

only l imited insight into the comprehens ive diagnosis .

In contrast , we have presented an organized , com-

prehensive approach to facial analysis. With this anal-

ysis normal facial traits are maintained and abnormal

characterist ics are corrected with or thodont ics and sur-

gery. Informat ion f rom facial examina t ion o f the patient

dictates which procedures result in opt imal cosmet ics

with Class I function. Mere correct ion to Class 1 oc-

c lusion can g ive random, and often poor, cosmet ic re-

suits. Further, arbitrary correct ion to Class I occlusion

does not ensure even presurgical cosmet ic levels, there-

fore esthetic guidel ines must be fo l lowed when deter-

mining surgical or thodont ic plans: For this purpose 19

key traits have been descr ibed.

REFERENCES I. Amett GW, Bergman RT. Facial Keys to Orthodontic Diagnosis

and Treatment Planning - Part I. AM J ORrHOD DEN'I-OFAC ORTIIOP 1993;103:299-312.

American Journal of Orthodontics and Dentofacial Orthopedics May 1993

Table VI. Maxi l la ry retrusion: c o m m o n facial

characterist ics o f maxi l la ry retrusion are listed

Mo.rillary retrusion

Normal lower one-third Normal interlabial gap Normal incisor exposure Normal smile No mentalis strain Straight to Class I!I profile angle Normal mandibular sulcus contour Increased nasal projection Nasal base deficiency Cheekbone/orbital rim deficiency Normal to increased nasolabial angle Normal throat length

Tab l e VII. Mandibu la r protrusion: c o m m o n

facial characteris t ics o f mandibular protrusion

are listed

Mandibular protrusion (may have increased vertical secondary to lack of dental interdigitation)

Normal to increased lower one-third Normal to increased interlabial gap Normal inciso~" exposure Normal tooth exposure with smile No increased mentalis strain Straight to Class III profile angle Normal to flat mandibular sulcus contour Normal nasal projection, alar base, and cheekbones Normal nasolabial angle Increased throat length

2. Farkas LG. Anthropometry of the head and face in medicine. New York: Elsevier North Holland Inc, 1981.

3. Moorrees CFA, Keen MR. Natural head position, a basic con- sideration in the interpretation of cephalomctrie radiographs. Am J Phys Anthropol 1958;16:213-34.

4. Wennstrom JL, Lindhe J, Sinclair F, Thilander B. Some periodontal tissue reactions to orthodontic tooth movement in mon- keys. J Clin Periodontol 1987;14:121-9.

5. Sadowsky C, Begole E. Long-tern1 effects of orthodontic treatment on periodontal health. AM J ORmOO 1981;80:156-72.

6. Wolford LM, ltilliard FW, Dugan DJ. Surgical treatment ob- jective. St. Louis: CV Mosby, 1985.

7. Legan HL, Burstone CJ. Soft tissue cephalometric analysis for orthognathic surgery. J Oral Surg 1980;38:744-51.

8. Burstone CJ. The integumental profile. AM J OR'roOD 1958;44:1- 25.

9. Talass MF, Baker RC. Soft tissue profile changes resulting from retraction of maxillary incisors. AM J ORTttOD DEN'I'OFAC OR'HIOP ! 987;9 ! (5):385-94.

10. Drobocky OB, Smith RJ. Changes in facial profile during orthodontic treatment with extraction of four first premolars. AM J ORTIIOD DENTOFAC ORTIIOP 1989;95(5):220-30.

I I. Lo FD, Hunter WS. Changes in nasolabial angle related to maxillary incisor retraction. Ar, t J OR'roOD 1982;82:384-91.

12. tloldaway RA. A soft-tissue cephalometric analysis and its use

American Journal of Orthodontics and Dentofacial Orthopedics Arnell and Bergtnan 411 ~?dume 103, No. 5

T a b l e VIII. C lass II m a l o c c l u s i o n s can be p roduced b y m a n d i b u l a r r e t rus ion (mos t c o m m o n ) , maxi l l a ry

p ro t rus ion ( rare*) , or ver t ica l max i l l a ry excess ( c o m m o n ) . (Facia l traits in the facial ana lys i s o f this ar t icle

d i s t ingu i sh a m o n g these skele ta l p r o b l e m s )

Class II profiles

Mandibular retrusion J Maxi'laD" protrusion I Vertical tncL~illary excess

Lower one-third Normal to decreased (1) Normal Increased lnterlabial gap Normal to decreased (I) Normal Increased Incisor exposure Normal Normal Increased Smile Normal Normal Gingiva Mentalis strain Yes (2) Yes (2) Yes Profile angle Decreased Normal to decreased Decreased Mandibular sulcus contour Increased (2) Increased (2) Increased Nasal projection Normal Normal to short Nornml Alar base Normal Normal to increased Normal Cheekbone Normal Normal Normal Nasolabial angle Normal Decreased Normal Throat length Decreased Normal Decreased

*Maxillary d~ntal protrusion is common (i.e., thumb sucking), but true maxillary basal bone with dental protrusion is extremely rare. (1) Decrease d secondary to deep bite. (2) Upper incisors impinge on lower lip and make lip closure strained.

T a b l e IX. Class III m a l occ l u s i on can be p roduced b y m a n d i b u l a r p ro t rus ion ( c o m m o n ) , max i l l a ry re t rus ion

(mos t c o m m o n ) , or ver t ica l max i l l a ry def ic iency (rare) . (Fac ia l trai ts in the facial arlalysis o f this ar t ic le

d i s t ingu i sh a m o n g these skeleta l pi-oblems)

Class I11 profiles

Mandibular protrusion J Ma~illat)" retrusion J Vertical maxillary deficiency I I

Lower one-third Normal to increased (1) Normal Decreased Interlabial gap Normal to increased (I) Normal Decreased Incisor exposure Normal Normal Decreased Smile Normal Normal Decreased incisor Mentalis strain None to increased None None, redundant Profile angle Straight to Class III Straight to Class Ill Straight to Class III Mandibular sulcus contour Normal to flat Normal Accentuated Nasal projection Normal Long Normal Alar base Normal Depressed Normal Cheekbones Normal Flat Normal Nasolabial angle Normal Normal to increased Normal to decreased Throat length Increased Normal Increased

(I) Increased secondary to lack of dental interdigitation.

in orthodontic treatment planning. Part I. AM J ORTIIOD

1983;84(1):1-28. 13. lloldaway RA. A soft-tissue cephalometfic analysis and its use

in orthodontic treatment planning. Part II. AM J ORTIIOD 1984;85:279-93.

14. Oliver BM. The influence of lip thickness and strain on upper lip response to incisor retraction. Ast J ORTIIOD 1982;82(2): 141-9.

15. Peck H, Peck S. A concept of facial esthetics. Angle Orthod 1970;40:284-317.

16. Burstone CJ. Lip posture and its significance in treatment planning. AM J ORTIIOD 1967;53:262-84.

17. Worms I"W, Spiedel TM, Bevis RR, Waite DE. Posttreatment stability and esthetics of orthognathic surgery. Angle Orthod 1980;50(4):251-73.

18. Worms FW, Isaacson R J, Speidel TM. Surgical orthodontic treatment planning: profile analysis and mandibular surgery. Angle Orthod 1976;46(1):1-25.

Reprint requests to: Dr. G. William Arnett 9 E. Pedregosa St. Santa Barbara, CA 93101

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