Cephalometric evaluation of the soft tissue profile

The development of cephalometrics laid the foundation for studying growth and development, treatment effects, facial forms, and esthetics. First described in 1931, initial cephalometric studies focused on analyzing the dentoskeletal pattern. Broadbent presented a mean facial pattern in “The face of the normal child,” and Brodie studied the growth pattern of the human head from the third month to the eighth year. In 1938, Brodie et al used cephalometrics as a clinical tool to analyze treated patients. A decade later, Downs established the range of skeletal and dental parameters that are associated with excellent occlusions. The cephalometric headfilm could now be used for diagnosing malocclusions. Steiner incorporated measurements from Downs, Riedel, and others into an analysis that could be used by practicing orthodontists in diagnosis and treatment evaluation. Ricketts also described a cephalometric method of planning treatment based on facial pattern and an estimate of its growth.

Although the importance of diagnosing and planning for the treatment of an esthetic result was emphasized by many, the measurement of soft tissue variables was lacking. Most thought that establishing normal dental relationships would result in an esthetic face. Hence, cephalometrics was embraced as a medium for evaluating teeth over basal bone and, therefore, the basis by which to extract premolars. As cephalometrics became the accepted method for orthodontic diagnosis, soft tissue measurements were introduced. Attention was initially paid to the areas most affected by orthodontic treatment. Ricketts’ esthetic plane, Steiner’s S-line, Burstone’s subnasale to pogonion plane, and Merrifield’s profile line and Z-angle were used to evaluate lip position in relation to the nose and chin. Lip morphology was examined with angular measures such as the nasolabial angle and upper lip angulation angle. Lip thickness was also examined. Subsequently, the length of the upper lip and the amount of maxillary incisor display at rest, the lengths of the lower lip and chin, and the interlabial gap were found to be important features in orthodontic treatment planning. Methods for evaluating chin position and thickness also were considered important in early soft tissue analyses.

In the 1950s, Burstone undertook a more extensive study of the “integumental” profile as an adjunct to treatment planning and posttreatment analysis. Using 7 soft tissue landmarks, he constructed 10 line segments from which he then computed 5 contour angles and 10 inclination angles. He concluded that average measurements are related to profile excellence. In a subsequent study, he measured the soft tissue thickness (extension measurements) in the lower face.

The Charles Tweed era

Nonextraction treatment was the law of the land until 1935, when Tweed discussed the extraction of premolars at, of all things, the annual meeting of the Edward H. Angle Society of Orthodontists. After practicing Angle’s nonextraction approach for a number of years, Tweed became dissatisfied with the relapse of incisor alignment and the worsening of facial esthetics in most of his patients. He concluded that optimal esthetics depended on the mandibular incisors’ being upright over the basal bone. Tweed’s philosophy of extracting premolars and uprighting the incisors was well founded in the treatment of patients with marked bimaxillary protrusion. However, he determined that optimal facial esthetics depended on having the mandibular incisor at 90° to the mandibular plane and, later, at 65° to the Frankfort incisor angle. As influential as Angle was in pushing his agenda of nonextraction treatment, Tweed was just as successful in promoting his extraction-retraction agenda. Tweed stated that “most of us agree that there is little likelihood of positioning the denture too far distally in relation to the basal bone, and that if we should err in this direction, function will drive the denture forward so that eventually it will find its functional balance point somewhere in the range of −5 to +5.” Extraction of the premolars soon became the norm in orthodontic treatment, even in patients without bimaxillary protrusion. But as these patients aged and were recalled for posttreatment examinations, the routine extraction of premolars began to be questioned. The postretention research by Little et al at the University of Washington showed that patients who started with crowding often had the crowding return. Most were missing 4 premolars, and many were also missing 4 third molars. Most of these patients were Caucasian, and the aging process combined with orthodontic flattening of the profile had resulted in faces that were thought to be less than ideal. Tweed’s approach had been overused, resulting in many patients looking bimaxillary retrusive, especially as they aged. It is interesting that some studies have shown no differences in the soft tissue profiles of patients treated with premolar extractions compared with those not treated.

The Charles Tweed era

Nonextraction treatment was the law of the land until 1935, when Tweed discussed the extraction of premolars at, of all things, the annual meeting of the Edward H. Angle Society of Orthodontists. After practicing Angle’s nonextraction approach for a number of years, Tweed became dissatisfied with the relapse of incisor alignment and the worsening of facial esthetics in most of his patients. He concluded that optimal esthetics depended on the mandibular incisors’ being upright over the basal bone. Tweed’s philosophy of extracting premolars and uprighting the incisors was well founded in the treatment of patients with marked bimaxillary protrusion. However, he determined that optimal facial esthetics depended on having the mandibular incisor at 90° to the mandibular plane and, later, at 65° to the Frankfort incisor angle. As influential as Angle was in pushing his agenda of nonextraction treatment, Tweed was just as successful in promoting his extraction-retraction agenda. Tweed stated that “most of us agree that there is little likelihood of positioning the denture too far distally in relation to the basal bone, and that if we should err in this direction, function will drive the denture forward so that eventually it will find its functional balance point somewhere in the range of −5 to +5.” Extraction of the premolars soon became the norm in orthodontic treatment, even in patients without bimaxillary protrusion. But as these patients aged and were recalled for posttreatment examinations, the routine extraction of premolars began to be questioned. The postretention research by Little et al at the University of Washington showed that patients who started with crowding often had the crowding return. Most were missing 4 premolars, and many were also missing 4 third molars. Most of these patients were Caucasian, and the aging process combined with orthodontic flattening of the profile had resulted in faces that were thought to be less than ideal. Tweed’s approach had been overused, resulting in many patients looking bimaxillary retrusive, especially as they aged. It is interesting that some studies have shown no differences in the soft tissue profiles of patients treated with premolar extractions compared with those not treated.

Changes in the soft tissue profile with growth and orthodontic treatment

What are the ramifications of orthodontic treatment on the soft tissue profile? We know that during orthodontic treatment, some changes occur as the result of our treatment, and some occur as a consequence of growth. When studying changes incident to growth, Subtelny found that the hard tissue chin assumes a more prominent position relative to the upper face, whereas the maxilla tends to become less protrusive. The skeletal profile thus becomes less convex. The soft tissues covering the maxilla increased to a greater degree, and Rudee found that the soft tissue chin often grew twice as much as pogonion. The nose undergoes even greater changes, increasing in prominence twice as much as the chin. The position of the lips was found to be closely related to the teeth and alveolar processes, which became more retruded in relation to the chin and bony facial plane.

Studies have shown a close association between orthodontic anterior tooth movement and lip movement. Although the thickness of the upper lip increases some, it will retract a significant percentage of the distance that the maxillary incisors retract. The lower lip retracts in relation to both maxillary and mandibular incisor retraction. Long-term studies have shown that after treatment, the soft tissue profile continues to flatten because of additional chin and nasal growth during maturation.

Orthodontic standards vs the public’s attitudes

Of course, the debate as to what constitutes an esthetic face continued. Angle’s reliance, first on Apollo’s face and then on the face resulting from nonextraction orthodontic treatment, was no longer reliable. Tweed’s initial attempts to flatten profiles with “marked bimaxillary protrusion” seemed reasonable, but extraction in patients with mild protrusion to achieve the cephalometric goal of an upright mandibular incisor began to be questioned. Who really was the best judge of an esthetic face? Most early studies on facial esthetics attempted to correlate faces judged to be esthetic by orthodontists with their underlying skeletal and dental patterns. The mandibular incisor to mandibular plane angle should be 90°. “Good” profiles had an ANB angle that did not exceed 2.5°. “Poor” profiles had a greater convex skeletal profile (N-A-P). To avoid the prejudices of orthodontists, artists were chosen to select esthetic profiles for study. However, artists also can have prejudices based on their training and study of art. Riedel thought it important to determine what “modern” concepts of facial esthetics might be from the viewpoint of the general public. He studied the profiles of queens and princesses from the Annual City of Seattle Seafair Week. Although the skeletal patterns were similar to those of previous studies on normal occlusion, the subjects showed greater protrusion of the maxillary denture base and greater axial inclination of the mandibular incisors. Peck and Peck attempted to further address the public’s attitude of esthetics by studying a large sample of television and motion picture personalities, beauty contests winners, and models. They concluded that the esthetic face presented in the mass media was more convex and more protrusive than our cephalometric standards of “normal.”

Was the northern European Caucasian ideal of beauty no longer the esthetic standard? From the 1960s to the 1980s, several things happened that changed the demographics of our patient population and the faces that we would see in the mass media. The greatest of these was the civil rights movement in the 1960s and the acceptance of African Americans in the mass media. Caucasian-looking African Americans were slowly being replaced by persons who had more African features, especially bimaxillary protrusion. The Vietnam War in the 1960s and 1970s resulted in the immigration of many Southeast Asians into our communities. The revolution in Iran brought a similar influx of Iranian immigrants. And the civil wars of Central America brought greater numbers of Hispanics into our communities and practices. Cephalometric analyses of different ethnic groups were now occurring with the thought of tailoring our orthodontic objectives to each patient’s ethnicity.

In this environment, was it possible that our esthetic standards of beauty were changing? Using profile photographs from leading fashion magazines in the 20th century, we attempted to answer that question. We examined the profiles of Caucasian female models and found that indeed the profiles shown in the later part of the 20th century were fuller in the area of the lips. And this trend was not unique to women. The male face in fashion magazines also had fuller lips in the later decades of the 20th century. And what about the African American profile? Previous studies had suggested that the esthetic African American profile was straighter and more like that of Caucasian people than the average African American profile. If the esthetic Caucasian face has fuller lips than the average Caucasian face, and the preferred African American face is more like that of Caucasian people in appearance, might these 2 profiles be more similar than their normal counterparts of the same race? To answer that question, we evaluated Caucasian and African American profile photographs from fashion magazines in the 1990s and compared them with Class I controls who were not models. The African American models and controls were almost identical. In contrast, the Caucasian models had greater lip prominence and vermilion display than did the Caucasian controls. Although the African American models showed greater lip prominence than the Caucasian models, the Caucasian models had more ethnic features than the African American models had Caucasian features. Might the esthetic African American profile shown in the mass media have experienced the same trend toward increasing lip fullness as did the esthetic Caucasian profile? Indeed, the same trend was found. Where the profiles in the mid 20th century were more like those of Caucasian people, the profiles shown in the 1990s were fuller in the area of the lips. Lip augmentation, which was an uncommon procedure just 30 years ago, has become a common cosmetic surgical procedure, especially for Caucasian women.