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A cephalometric evaluation of American Negro women
A cephalometric evaluation American Negro worn/en
of
Raymond J. Fonseca, D.M.D.,* and W. Douglas Klein, D.M.D.** Chapel
Hill,
N.
C.,
and
Portland,
Ore.
T
he racial subgroups of man are differentiated, in part, on the basis of their facial features. In the modem era of combined surgical-orthodontic therapy, mom adults from different racial backgrounds are receiving treatment. The accurate use of cephalometric roentgenology is essential in growth prediction, diagnosis, and treatment planning. However, an important part of it is predicated on the knowledge of standard or normal values of the patient population. Although it is a common assumption that there are intra- and interracial variations of normal, them is very little firm normative information about the characteristics of one very large portion of our population, The American adult female Negro. The present investigation was designed, therefore, to determine normal cephalometric measurements of the American Negro woman. If these results were found to be significantly different from the Caucasian norms, it would indicate that diagnostic workups and treatment plans should not be interchanged from one racial group to another without a consideration of the racial norms of each group. Review of the lbrature Several early anthropologic studies on non-white ethnic groups demonstrated that significant skeletal, dental, and soft-tissue differences exist between the races.5’ “, “. ‘* One such study by Hnllicka,l” in 1928, revealed some interesting differences. The face and mouth of the American black were larger than those of the American white, whereas the head and ears were smaller. The nose of the black was broader, shorter, and flatter. Since the advent of cephalometry, several analyses have been presented by various authors. After the introduction of Downs’ analysis’ several orthodontists investigated whether his mean skeletofacial measurements of American Caucasians were applicable to other ethnic groups6 Altemus’ compared the cephalometric relationships of the American Negro to the Downs analysis. The skeletal pattern was more protrusive and the teeth were more procumbent in the black group than in the white group of Downs. He also studied’ the soft-tissue profiles of Negro children by a method described by Burstone. Results showed that means were similar to those of Caucasians in the areas of menton, incisionstomion, and glabella; yet Negroes had greater values in other areas except subspinale, which was smaller. In all these studies it was demonstrated that the Downs normal values were not applicable in Negroes. *Assistant **Senior
152
Professor, Department of Oral Surgery, University Resident in Oral Surgery, University of Oregon.
of North
Carolina.
Volume 13 Number 2
Cephalometric
evaluation
of American Negro women
153
Fig. 1. Skeletal measurements taken on the Negro sample. Fig. 2. Dentoalveolar measurements taken on the Negro sample.
Drummond,8 in 1968, using various measurements from the Riedel13 and Holdaway analyses, determined lateral cephalometric norms in the American Negro. He compared his sample with the norms of forty Southern Caucasian children taken from a study performed at the University of Alabama” and demonstrated differences between the two groups. The American Negro children had a steeper mandibular plane, bimaxillary dental protrusion, and an anterior placement of the maxilla. Kowalski, Nasjleti, and Walker” compared the distributions of the Steineri variables in large samples of American black and white men. They concluded that the proclination of the lower incisor to the NB line was much higher in Negroes, as was the degree of maxillary prognathism, whereas the interincisal angle was considerably more obtuse in the Caucasian sample. The forty Negroes used in the Drummond sample had ranged in age from 8 to 23 years, and Altemus performed his study on children representing a chronologic age of 12 to 16 years. When one considers that orthodontists are mainly interested in the diagnosis, growth prediction, and treatment planning of children and adolescents, it is understandable that these two groups were the subjects of the earlier investigations. The combined surgical and orthodontic approach has established a need, however, to document cephalometric norms for the adult female Negro population. Materials and methods Forty Negro women with an age range from 20 to 30 years and a mean age of 24.6 years were selected for study. All subjects had a Class I molar and/or canine relationship, a clinically acceptable occlusion, and good general health, with no obvious facial abnormalities. The subjects were placed in natural head position, and standardized lateral cephalometric roentgenogmms were taken with a Broadbent-Bolton cephalometer. The lateral cephalograms were traced and measured by standard techniques, and linear and angular measurements were recorded to the nearest millimeter and degree, respectively.
154
Fonseca
and
Klein
Nasion
-S.T.
Nasion
POG - ST. POG
?
Fig. 3. Soft-tissue measurements taken on the Negro sample.
Table 1. A comparison of cephalometric skeletal values between Negro and Caucasiansamples Negro Skeletal
measurements
SNA SNB ANB FNA FNB Y axis SN-Go-Gn N-A/A-Pog MPA
Mean
88.2 83.9 4.3 93.1 88.7 65.5 32.9 54.6155.5 27.7
sample Standard
Caucasian error
0.7 0.7 0.4 0.6 0.1 0.7 I .o 0.6/0.9
Mean
82.5 79.6 3.0 88.0 8.5.1 67.3 32.1 59.5152 26.6
Standard
sample error
1.0 I.0 0.5 0.8 I.0 0.9 1.3 0.7/0.9 1.3
Probability
0.001 0.01 0.05 0.001 0.01 N.S. N.S. 0.001/0.01 N.S.
Skeletal, dental, and soft-tissue analyses of the cephalogram were performed as described in Figs. 1, 2, and 3. The results of the measurements were then compared to a group of twenty Caucasian female subjects ranging in age from 18 to 25 years. The mean age of the group was 20 years. The same criteria for selection and cephalographic technique were used as described above for the Negro sample. Comparisons were then made between the mean and standard error, using the Student t test to determine whether any of the Negro norms were statistically different from the Caucasian norms.
Volume 73 Number
Cephalometric
2
evaluation
of American
Negro
women
155
Table II. A comparison of cephalometric dentoalveolar values between Negro and Caucasian samples Negro Dental
measurements
INA INA INB INB I/I I-SN IMPA FMIA
Mean
(degrees) (mm.) (degrees) (mm.)
26. I 6.6 38.5 9.3 112.8 114.0 101.2 51.1
(degrees)
Caucasian
sample Standard
error
Mean
1.3 0.5 I.1 0.3 1.5 1.3 I.1 1.1
Standard
23. I 3.4 23.9 4.6 131.0 105.6 92.5 61.0
sample error
Probability
1.4 0.4 1.5 0.6 2.5 1.9 1.7 2.2
N.S. 0.001 0.001 0.001 0.001 0.001 0.001 0.001
Table Ill. A comparison of cephalometric soft tissue values between Negro and Caucasian samples Negro So&tissue Nasion-soft-tissue
sample
Mean
nasion sulcus plane of
6.7 31.2 14.0 24.9 11.2
0.2 0.5 0.3 0.5 0.3
6.8 33.5 13.9 17.8 11.1
0.3 0.7 0.3 0.9 0.3
N.S. 0.02 N.S. 0.001 N.S.
of
13.1
0.3
12.8
0.3
N.S.
plane sulcus
23.2 13.2 14.0
0.5 0.4 0.3
15.8 11.9 12.1
0.8 0.3 0.4
0.001 0.02 0.001
Point A-superior labial Lab&e superius-facial Labrale superius-labial maxillary incisor Labrale inferius-labial mandibular incisor Lab&e inferius-facial Point B-inferior labial Pogonion-Point C
error
Mean
Standard
sample
measurements
Nasaltip-facial plane
Standard
Caucasian
error
Probability
Results
Skeletal, dental, and soft-tissue measurements for the Negro sample and a comparison with the Caucasian sample are shown in Tables I, II, and III and Figs. 4, 5, 6, 7, and 8. The means and standard deviations of the white variables compared favorably with those of other studies. 3, 4, l4 The maxilla and mandible in relation to the cranial base were found to be more anteriorly placed in the black as measured by the SNA, SNB, FNA, and FNB angles. The inclination of the mandible (AN-Go-Gn and the Tweed FMPA) was essentially the same in both samples. Middle facial height (N-A) was greater in Caucasian subjects, whereas lower facial height (A-Pog) was larger in the Negro group. The ratio of middle facial to lower facial height was 8 to 7 in the Caucasian sample and 1 to 1 in the Negro sample. There was also a significant difference in the proclination of the lower incisor between the two populations as revealed by measurement of the INB, IMPA, and FMIA. The lower incisor of the Negro sample was much more procumbent, whereas the maxillary incisor showed only a slight degree of procumbency when compared to the Caucasian
156
Fonsrca
and
Klrirl
Fig. 4. A comparison of Negro [left) and Caucasian (right) skeletal measurements.
Fig. 5. A comparison of Negro (left) and Caucasian (right) dentwakeoiar
measurements.
group. Upper and lower incisors met at a more acute angle because of this increased proclination. A comparison of the soft-tissue profiles between the two groups showed significant differences. Nasal tip projection (facial plane to nasal tip) was shorter in the Negro group, whereas upper and lower lip anteroposterior projection (superior and inferior labialis to facial plane) was significantly greater. However, soft-tissue thickness of the upper and lower lips was essentially the same. Distances between point B and the inferior labial
Volume 13 Number 2
Cephalometric
evaluation
of American
Negro women
157
mm
Fig. 6. A comparison of Negro (left) and Caucasian (right) soft-tissue measurements.
1 54.6 mm
, 1:
55.1 mm
J’
Fig. 7. A comparison of Negro (left) and Caucasian (right) middle and lower facial heights.
sulcus and between pogonion and soft-tissue pogonion were larger in the Negro group. The measurements of point A to superior labial sulcus and nasion to soft-tissue nasion were approximately the same in both groups. Discussion These studies using lateral cephalograms on Negro subjects have shown that there are differences in the skeletal, dental, and soft-tissue profiles when compared to Caucasians.
158
Fonseca
and
Klein
Fig. 8. A comparison of Negro (left) and Caucasian (right) upper and lower lip thickness.
A skeletal bimaxillary protrusion existed in the black females when compared to the white females. Drummonds’ study showed similar results in the direction but not in the magnitude of diffenznce between the two groups. This could possibly be explained by the ages of his subjects, which ranged from 8 to 23 years, and the inclusion of both sexes. Since some of his subjects had not completed their growth, mandibular and maxillary skeletal measurements could be different when compared to an adult sample. Not only was the relationship of the maxilla and mandible to the cranial base more prognathic in the present study than in the Drummond variables, but the angle formed by the intersection of the mandibular plane and the cranial base (SN-Go-Gn) was not as steep as in his sample of younger patients . The SNA, SNB, ANB, and AN-Go-Gn angular measurements determined in this investigation compared more favorably with Kowalski, Nasjleti, and Walker’s” findings on black adult male subjects. This indicated that perhaps growth of the maxillomandibular complex was a reason for the difference between the present study and Drummond’s investigation. Although the I-NA angle was not significantly different in the two groups investigated, significant differences did exist in the I-SN (angular) and I-NA (linear) measurements. It appeared therefore, that a maxillary dentoalveolar protrusion did exist. The mandibular incisor was considerably more protrusive in the Negro subject as determined by the ?-NB (angular)T-NB (linear) and iMPA variables. The acuteness of the II I angle substantiated the existence of a bimaxillary dentoalveolar protrusion in the Negro woman. The soft-tissue profile differed mainly in the decreased anteroposterior projection of the nose and the forward position of the upper and lower lips in relation to the facial plane. However, lip thickness, when compared to the Burstone study of twenty-five young adult females with a mean age of 23.8 years was not significantly different. In the present study lip thickness was not found to differ between black and white groups. The most significant soft-tissue measurement was the projection of the upper and lower lips beyond the facial plane when compared to the Caucasian sample, which reflected the protrusive
Volume 13 Number
2
Cephalometric
evaluation
of American
Negro
women
159
pattern of the underlying skeletal and dental framework. What clinically appears to be an increase in lip thickness in the Negro woman is probably an eversion of the lips revealing more lip tissue between upper and lower vermilion borders. The differences between black and white groups for the other soft-tissue measurements were less than 2 mm. and, although some may be numerically significant, the practical difference is insignificant when one considers the variance of intraracial measurements. The observed differences suggest that different cephalometric norms may be necessary for the treatment of Negro and Caucasian populations. Summary
A cephalometric study of forty American Negro women with an average age of 24.6 years and a Class I molar and/or canine relationship was performed. When measurements were compared to a control population of twenty Caucasian women, using several standard analyses, significant differences were demonstrated between the sample populations. 1. The maxilla and mandible were more protrusive in the Negro sample. 2. The upper and lower incisors were more proclined and the interincisal angle was more acute in the Negro sample. 3. Middle facial height was shorter and lower facial height was longer in the Negro sample. 4. The projection of the soft-tissue nasal tip was less in the Negro sample. 5. The projection of the upper and lower lips as related to the facial plane was greater in the Negro sample. 6. Lip thickness was approximately the same in the two groups. REFERENCES 1. Altemus, L. A.: A comparison of cephalofacial relationships, Angle Orthond. 30: 223-239, 1960. 2. Altemus, L. A.: Comparative integumental relationships, Angle Orthod. 33: 217-221, 1963. 3. Anderson, J. P.: A serial cephalometric study of soft tissue profile changes in orthodontically treated cases ten years out of retention, Master’s Thesis, University of Washington, Seattle, Washington, 1971. 4. Burstone, C. J.: Integumental contours and extension patterns, Angle Orthond. 29: 93-104, 1959. 5. Cameron, J.: Craniometric studies, XIV. The level of the nasion in white and negro, Am. J. Phys. Antbropol. 12: 164-175, 1928. 6. Cotton, W. N., Takano, W. S., Wong, M. N., and Wylie, W. L.: The Downs analysis applied to three other ethnic groups, Angle Orthond. 21: 2 13-220, 195 1. 7. Downs, W. B.: Variations in facial relationships: Their significance in treatment and prognosis, AM. J. ORTHOND. 34: 812-840, 1948. 8. Drummond, R.: A determination of cephalometric norms for the negro race, AM. J. ORTHOND. 54: 670-682, 1968. 9. Holdaway, R. A.: Changes in relationship of point A and B during orthodontic treatment, AM. J. ORTHOND. 42: 177-193, 1956. 10. Hrdlicka, A.: The full-blood American Negro, Am. J. Phys. Anthropol. 12: 15-33, 1928. 11. Kowalski, C. J., Nasjleti, C. E., and Walker, G. F.: Differential diagnosis of adult male black and white populations, Angle Orthond. 44: 346-350, 1974. 12. Limson, M.: Observations on the bones of the skull in white and Negro fetuses and infants, Carnegie Institute in Washington (Publication 433) 136: 205-222 (Biological Abstract, Vol. 9, 1935). 13. Riedel, R. A.: The relation of maxillary structures to cranium in malocclusion and in normal occlusion, Angle Orthond. 22: 142-145, 1952. 14. Riolo, M. L., Moyers, R. E., McNomara, J. A., Jr., and Hunter, W. S.: An atlas of craniofacial growth: Cephalometric standards from the University School of Growth Study, the University of Michigan, Monograph No. 2, Craniofacial Growth Series, pp. 321-330, 1974.
160
Fonseca
und
Klein
15. Steiner, C. C.: Cephalometrics for you and me, AM, J. ORTHOD. 39: 729-755, 1953. 16. Taylor, W. H., and Hitchcock, H. P.: The Alabama Analysis, AM. J. ORTHOD. 52: 24.5-265, 1966. 17. Todd, T. W., and Lindala, A.: Dimensions of the body: whites and American Negroes of both sexes, Am. J. Phys. Anthropol. 12: 35-119, 1928. 18, Todd, T. W., and Tracey, B.: Racial features in the American Negro cranium. Am. J. Phys. Anthropol. 1.5: 53-l 10, 1930. 209 H, University
THE .JOWMAL February,
of North
89 YEARS
Carolina
School
of Dentistry
(27514)
AGO
1918
The Income Tax Act of 1917, levying on aH incomes over $2,000, and those of the unmanied over $1,000, will apply to many professional men not affected by former income tax laws. Unn?arriedpersons must pay 2% on net income over $1,000, and 2% additional on all over $3,000. Married parsons or heads of farnil& must pay 2% on net income over $W3OO, and % add&W& on all over $4,000, less an exemption of $200 for each dependent child under 18 years of age. In a&&ion a surtax of 1% must be paid on income over $5,000,2% over $7,500, and 3?k over $10,000. There is an increaaingrateup to $2,000,000, but any exclusive dentist with afive fiwe income should not waste his valuable time or risk his mental poise by sordid calculation, and any “popular price” generat practitioner who has “speeded up” to more than $10,000 need not worry about income tax. The administrator will attend to this along with the other details in closing the estate. (Clarence 0. Simpson, M.D.: lncome Tax lnformation for Dentists. international Journal of Orthodontia, predecessor of the Afnerican Journal of orfhodontics, 3: 79, 1918.)
of
Raymond J. Fonseca, D.M.D.,* and W. Douglas Klein, D.M.D.** Chapel
Hill,
N.
C.,
and
Portland,
Ore.
T
he racial subgroups of man are differentiated, in part, on the basis of their facial features. In the modem era of combined surgical-orthodontic therapy, mom adults from different racial backgrounds are receiving treatment. The accurate use of cephalometric roentgenology is essential in growth prediction, diagnosis, and treatment planning. However, an important part of it is predicated on the knowledge of standard or normal values of the patient population. Although it is a common assumption that there are intra- and interracial variations of normal, them is very little firm normative information about the characteristics of one very large portion of our population, The American adult female Negro. The present investigation was designed, therefore, to determine normal cephalometric measurements of the American Negro woman. If these results were found to be significantly different from the Caucasian norms, it would indicate that diagnostic workups and treatment plans should not be interchanged from one racial group to another without a consideration of the racial norms of each group. Review of the lbrature Several early anthropologic studies on non-white ethnic groups demonstrated that significant skeletal, dental, and soft-tissue differences exist between the races.5’ “, “. ‘* One such study by Hnllicka,l” in 1928, revealed some interesting differences. The face and mouth of the American black were larger than those of the American white, whereas the head and ears were smaller. The nose of the black was broader, shorter, and flatter. Since the advent of cephalometry, several analyses have been presented by various authors. After the introduction of Downs’ analysis’ several orthodontists investigated whether his mean skeletofacial measurements of American Caucasians were applicable to other ethnic groups6 Altemus’ compared the cephalometric relationships of the American Negro to the Downs analysis. The skeletal pattern was more protrusive and the teeth were more procumbent in the black group than in the white group of Downs. He also studied’ the soft-tissue profiles of Negro children by a method described by Burstone. Results showed that means were similar to those of Caucasians in the areas of menton, incisionstomion, and glabella; yet Negroes had greater values in other areas except subspinale, which was smaller. In all these studies it was demonstrated that the Downs normal values were not applicable in Negroes. *Assistant **Senior
152
Professor, Department of Oral Surgery, University Resident in Oral Surgery, University of Oregon.
of North
Carolina.
Volume 13 Number 2
Cephalometric
evaluation
of American Negro women
153
Fig. 1. Skeletal measurements taken on the Negro sample. Fig. 2. Dentoalveolar measurements taken on the Negro sample.
Drummond,8 in 1968, using various measurements from the Riedel13 and Holdaway analyses, determined lateral cephalometric norms in the American Negro. He compared his sample with the norms of forty Southern Caucasian children taken from a study performed at the University of Alabama” and demonstrated differences between the two groups. The American Negro children had a steeper mandibular plane, bimaxillary dental protrusion, and an anterior placement of the maxilla. Kowalski, Nasjleti, and Walker” compared the distributions of the Steineri variables in large samples of American black and white men. They concluded that the proclination of the lower incisor to the NB line was much higher in Negroes, as was the degree of maxillary prognathism, whereas the interincisal angle was considerably more obtuse in the Caucasian sample. The forty Negroes used in the Drummond sample had ranged in age from 8 to 23 years, and Altemus performed his study on children representing a chronologic age of 12 to 16 years. When one considers that orthodontists are mainly interested in the diagnosis, growth prediction, and treatment planning of children and adolescents, it is understandable that these two groups were the subjects of the earlier investigations. The combined surgical and orthodontic approach has established a need, however, to document cephalometric norms for the adult female Negro population. Materials and methods Forty Negro women with an age range from 20 to 30 years and a mean age of 24.6 years were selected for study. All subjects had a Class I molar and/or canine relationship, a clinically acceptable occlusion, and good general health, with no obvious facial abnormalities. The subjects were placed in natural head position, and standardized lateral cephalometric roentgenogmms were taken with a Broadbent-Bolton cephalometer. The lateral cephalograms were traced and measured by standard techniques, and linear and angular measurements were recorded to the nearest millimeter and degree, respectively.
154
Fonseca
and
Klein
Nasion
-S.T.
Nasion
POG - ST. POG
?
Fig. 3. Soft-tissue measurements taken on the Negro sample.
Table 1. A comparison of cephalometric skeletal values between Negro and Caucasiansamples Negro Skeletal
measurements
SNA SNB ANB FNA FNB Y axis SN-Go-Gn N-A/A-Pog MPA
Mean
88.2 83.9 4.3 93.1 88.7 65.5 32.9 54.6155.5 27.7
sample Standard
Caucasian error
0.7 0.7 0.4 0.6 0.1 0.7 I .o 0.6/0.9
Mean
82.5 79.6 3.0 88.0 8.5.1 67.3 32.1 59.5152 26.6
Standard
sample error
1.0 I.0 0.5 0.8 I.0 0.9 1.3 0.7/0.9 1.3
Probability
0.001 0.01 0.05 0.001 0.01 N.S. N.S. 0.001/0.01 N.S.
Skeletal, dental, and soft-tissue analyses of the cephalogram were performed as described in Figs. 1, 2, and 3. The results of the measurements were then compared to a group of twenty Caucasian female subjects ranging in age from 18 to 25 years. The mean age of the group was 20 years. The same criteria for selection and cephalographic technique were used as described above for the Negro sample. Comparisons were then made between the mean and standard error, using the Student t test to determine whether any of the Negro norms were statistically different from the Caucasian norms.
Volume 73 Number
Cephalometric
2
evaluation
of American
Negro
women
155
Table II. A comparison of cephalometric dentoalveolar values between Negro and Caucasian samples Negro Dental
measurements
INA INA INB INB I/I I-SN IMPA FMIA
Mean
(degrees) (mm.) (degrees) (mm.)
26. I 6.6 38.5 9.3 112.8 114.0 101.2 51.1
(degrees)
Caucasian
sample Standard
error
Mean
1.3 0.5 I.1 0.3 1.5 1.3 I.1 1.1
Standard
23. I 3.4 23.9 4.6 131.0 105.6 92.5 61.0
sample error
Probability
1.4 0.4 1.5 0.6 2.5 1.9 1.7 2.2
N.S. 0.001 0.001 0.001 0.001 0.001 0.001 0.001
Table Ill. A comparison of cephalometric soft tissue values between Negro and Caucasian samples Negro So&tissue Nasion-soft-tissue
sample
Mean
nasion sulcus plane of
6.7 31.2 14.0 24.9 11.2
0.2 0.5 0.3 0.5 0.3
6.8 33.5 13.9 17.8 11.1
0.3 0.7 0.3 0.9 0.3
N.S. 0.02 N.S. 0.001 N.S.
of
13.1
0.3
12.8
0.3
N.S.
plane sulcus
23.2 13.2 14.0
0.5 0.4 0.3
15.8 11.9 12.1
0.8 0.3 0.4
0.001 0.02 0.001
Point A-superior labial Lab&e superius-facial Labrale superius-labial maxillary incisor Labrale inferius-labial mandibular incisor Lab&e inferius-facial Point B-inferior labial Pogonion-Point C
error
Mean
Standard
sample
measurements
Nasaltip-facial plane
Standard
Caucasian
error
Probability
Results
Skeletal, dental, and soft-tissue measurements for the Negro sample and a comparison with the Caucasian sample are shown in Tables I, II, and III and Figs. 4, 5, 6, 7, and 8. The means and standard deviations of the white variables compared favorably with those of other studies. 3, 4, l4 The maxilla and mandible in relation to the cranial base were found to be more anteriorly placed in the black as measured by the SNA, SNB, FNA, and FNB angles. The inclination of the mandible (AN-Go-Gn and the Tweed FMPA) was essentially the same in both samples. Middle facial height (N-A) was greater in Caucasian subjects, whereas lower facial height (A-Pog) was larger in the Negro group. The ratio of middle facial to lower facial height was 8 to 7 in the Caucasian sample and 1 to 1 in the Negro sample. There was also a significant difference in the proclination of the lower incisor between the two populations as revealed by measurement of the INB, IMPA, and FMIA. The lower incisor of the Negro sample was much more procumbent, whereas the maxillary incisor showed only a slight degree of procumbency when compared to the Caucasian
156
Fonsrca
and
Klrirl
Fig. 4. A comparison of Negro [left) and Caucasian (right) skeletal measurements.
Fig. 5. A comparison of Negro (left) and Caucasian (right) dentwakeoiar
measurements.
group. Upper and lower incisors met at a more acute angle because of this increased proclination. A comparison of the soft-tissue profiles between the two groups showed significant differences. Nasal tip projection (facial plane to nasal tip) was shorter in the Negro group, whereas upper and lower lip anteroposterior projection (superior and inferior labialis to facial plane) was significantly greater. However, soft-tissue thickness of the upper and lower lips was essentially the same. Distances between point B and the inferior labial
Volume 13 Number 2
Cephalometric
evaluation
of American
Negro women
157
mm
Fig. 6. A comparison of Negro (left) and Caucasian (right) soft-tissue measurements.
1 54.6 mm
, 1:
55.1 mm
J’
Fig. 7. A comparison of Negro (left) and Caucasian (right) middle and lower facial heights.
sulcus and between pogonion and soft-tissue pogonion were larger in the Negro group. The measurements of point A to superior labial sulcus and nasion to soft-tissue nasion were approximately the same in both groups. Discussion These studies using lateral cephalograms on Negro subjects have shown that there are differences in the skeletal, dental, and soft-tissue profiles when compared to Caucasians.
158
Fonseca
and
Klein
Fig. 8. A comparison of Negro (left) and Caucasian (right) upper and lower lip thickness.
A skeletal bimaxillary protrusion existed in the black females when compared to the white females. Drummonds’ study showed similar results in the direction but not in the magnitude of diffenznce between the two groups. This could possibly be explained by the ages of his subjects, which ranged from 8 to 23 years, and the inclusion of both sexes. Since some of his subjects had not completed their growth, mandibular and maxillary skeletal measurements could be different when compared to an adult sample. Not only was the relationship of the maxilla and mandible to the cranial base more prognathic in the present study than in the Drummond variables, but the angle formed by the intersection of the mandibular plane and the cranial base (SN-Go-Gn) was not as steep as in his sample of younger patients . The SNA, SNB, ANB, and AN-Go-Gn angular measurements determined in this investigation compared more favorably with Kowalski, Nasjleti, and Walker’s” findings on black adult male subjects. This indicated that perhaps growth of the maxillomandibular complex was a reason for the difference between the present study and Drummond’s investigation. Although the I-NA angle was not significantly different in the two groups investigated, significant differences did exist in the I-SN (angular) and I-NA (linear) measurements. It appeared therefore, that a maxillary dentoalveolar protrusion did exist. The mandibular incisor was considerably more protrusive in the Negro subject as determined by the ?-NB (angular)T-NB (linear) and iMPA variables. The acuteness of the II I angle substantiated the existence of a bimaxillary dentoalveolar protrusion in the Negro woman. The soft-tissue profile differed mainly in the decreased anteroposterior projection of the nose and the forward position of the upper and lower lips in relation to the facial plane. However, lip thickness, when compared to the Burstone study of twenty-five young adult females with a mean age of 23.8 years was not significantly different. In the present study lip thickness was not found to differ between black and white groups. The most significant soft-tissue measurement was the projection of the upper and lower lips beyond the facial plane when compared to the Caucasian sample, which reflected the protrusive
Volume 13 Number
2
Cephalometric
evaluation
of American
Negro
women
159
pattern of the underlying skeletal and dental framework. What clinically appears to be an increase in lip thickness in the Negro woman is probably an eversion of the lips revealing more lip tissue between upper and lower vermilion borders. The differences between black and white groups for the other soft-tissue measurements were less than 2 mm. and, although some may be numerically significant, the practical difference is insignificant when one considers the variance of intraracial measurements. The observed differences suggest that different cephalometric norms may be necessary for the treatment of Negro and Caucasian populations. Summary
A cephalometric study of forty American Negro women with an average age of 24.6 years and a Class I molar and/or canine relationship was performed. When measurements were compared to a control population of twenty Caucasian women, using several standard analyses, significant differences were demonstrated between the sample populations. 1. The maxilla and mandible were more protrusive in the Negro sample. 2. The upper and lower incisors were more proclined and the interincisal angle was more acute in the Negro sample. 3. Middle facial height was shorter and lower facial height was longer in the Negro sample. 4. The projection of the soft-tissue nasal tip was less in the Negro sample. 5. The projection of the upper and lower lips as related to the facial plane was greater in the Negro sample. 6. Lip thickness was approximately the same in the two groups. REFERENCES 1. Altemus, L. A.: A comparison of cephalofacial relationships, Angle Orthond. 30: 223-239, 1960. 2. Altemus, L. A.: Comparative integumental relationships, Angle Orthod. 33: 217-221, 1963. 3. Anderson, J. P.: A serial cephalometric study of soft tissue profile changes in orthodontically treated cases ten years out of retention, Master’s Thesis, University of Washington, Seattle, Washington, 1971. 4. Burstone, C. J.: Integumental contours and extension patterns, Angle Orthond. 29: 93-104, 1959. 5. Cameron, J.: Craniometric studies, XIV. The level of the nasion in white and negro, Am. J. Phys. Antbropol. 12: 164-175, 1928. 6. Cotton, W. N., Takano, W. S., Wong, M. N., and Wylie, W. L.: The Downs analysis applied to three other ethnic groups, Angle Orthond. 21: 2 13-220, 195 1. 7. Downs, W. B.: Variations in facial relationships: Their significance in treatment and prognosis, AM. J. ORTHOND. 34: 812-840, 1948. 8. Drummond, R.: A determination of cephalometric norms for the negro race, AM. J. ORTHOND. 54: 670-682, 1968. 9. Holdaway, R. A.: Changes in relationship of point A and B during orthodontic treatment, AM. J. ORTHOND. 42: 177-193, 1956. 10. Hrdlicka, A.: The full-blood American Negro, Am. J. Phys. Anthropol. 12: 15-33, 1928. 11. Kowalski, C. J., Nasjleti, C. E., and Walker, G. F.: Differential diagnosis of adult male black and white populations, Angle Orthond. 44: 346-350, 1974. 12. Limson, M.: Observations on the bones of the skull in white and Negro fetuses and infants, Carnegie Institute in Washington (Publication 433) 136: 205-222 (Biological Abstract, Vol. 9, 1935). 13. Riedel, R. A.: The relation of maxillary structures to cranium in malocclusion and in normal occlusion, Angle Orthond. 22: 142-145, 1952. 14. Riolo, M. L., Moyers, R. E., McNomara, J. A., Jr., and Hunter, W. S.: An atlas of craniofacial growth: Cephalometric standards from the University School of Growth Study, the University of Michigan, Monograph No. 2, Craniofacial Growth Series, pp. 321-330, 1974.
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15. Steiner, C. C.: Cephalometrics for you and me, AM, J. ORTHOD. 39: 729-755, 1953. 16. Taylor, W. H., and Hitchcock, H. P.: The Alabama Analysis, AM. J. ORTHOD. 52: 24.5-265, 1966. 17. Todd, T. W., and Lindala, A.: Dimensions of the body: whites and American Negroes of both sexes, Am. J. Phys. Anthropol. 12: 35-119, 1928. 18, Todd, T. W., and Tracey, B.: Racial features in the American Negro cranium. Am. J. Phys. Anthropol. 1.5: 53-l 10, 1930. 209 H, University
THE .JOWMAL February,
of North
89 YEARS
Carolina
School
of Dentistry
(27514)
AGO
1918
The Income Tax Act of 1917, levying on aH incomes over $2,000, and those of the unmanied over $1,000, will apply to many professional men not affected by former income tax laws. Unn?arriedpersons must pay 2% on net income over $1,000, and 2% additional on all over $3,000. Married parsons or heads of farnil& must pay 2% on net income over $W3OO, and % add&W& on all over $4,000, less an exemption of $200 for each dependent child under 18 years of age. In a&&ion a surtax of 1% must be paid on income over $5,000,2% over $7,500, and 3?k over $10,000. There is an increaaingrateup to $2,000,000, but any exclusive dentist with afive fiwe income should not waste his valuable time or risk his mental poise by sordid calculation, and any “popular price” generat practitioner who has “speeded up” to more than $10,000 need not worry about income tax. The administrator will attend to this along with the other details in closing the estate. (Clarence 0. Simpson, M.D.: lncome Tax lnformation for Dentists. international Journal of Orthodontia, predecessor of the Afnerican Journal of orfhodontics, 3: 79, 1918.)