ORIGINAL ARTICLES
Vertical growth of the anterior face: A new approach A.S.W.M.R. Ligthelm-Bakker," E. Wattel, b I.H. Uljee, b and B. PrahI-Andersen" Amsterdam, The Netherlands
The mechanism of anterior vertical facial growth was studied in normal subjects between 7 and 22 years of age. This subsample (n = 60) of participants in the Nijmegen Growth Study was representative of normal variation with respect to vertical facial proportions. A negative correlation was found between the average growth rate of the upper and lower anterior facial height in boys. Boys with a relatively large.facial height exhibited a higher than average growth rate of the lower anterior facial height compared with the upper facial height. In girls a similar trend was present. The individual average growth rate of the anterior upper and lower facial height maintains or accentuates the early established facial form. (AM J ORTHOD DENTOFACORTHOP 1992;101:509-13.) D i f f e r e n t i a l growth of the upper and lower components I of the face seems to be important in the developmen! of different facial patterns. The development of subjects with open and deep bite faces have been studied in detail *,2 and subjects were found to grow differently. 2~ Subjects with deep bite faces show an increased upper anterior facial height, whereas increased lower anterior facial height is observed in subjects with open bite faces. Usually these dimensions of the face are studied cross-sectionally and from a morphologic point of view. Several authors 37 found that the total anterior facial height was relatively large in subjects with open bite faces and reduced in subjects with deep bite faces. The hypothesis that a key factor contributing to the open bite structure is a reduction in posterior facial height 3'4"8'9 was rejected by Nanda 2 and indirectly by Bj6rk ~~ and Fields et al. 7 In contrast to the former authors they found that ramal height is often excessive in subjects with open bite faces, and although anterior facial height demonstrated significant differences between different facial patterns, no significant differences in posterior facial height were found. These studies of the facial structure give little insight into the actual growth mechanisms of the face. Longitudinal data analysis is more meaningful in this respect. ''2 Because the postnatal facial growth changes are small with a relatively large variation, they are not easily observed when dealing with a crosssectional data set. Also, when analyzing the growth of children according to chronologic age, differences in general maturation or biologic age may add to the variation found. It could also be argued that instead of Supported in part by a grant from "'tier Prc',entiefonds," The tlague, The Netherlands. 'Department of Orthodontics, Academic Centre for. Dentist D' Amsterdam
(ACTA). *D,:partment of Mathematics, Vrije Universiteit Amsterdam. 8/1/27062
describing longitudinal changes in selected extreme facial types, 2 one should study the complete range of normal facial development to describe the growth mechanisms of the face. By doing this, the level of generalization is increased. The purpose of this study was to analyze the relationship between the rate of growth in uplSer and lower anterior facial height in normal children. MATERIAL AND METHODS
The subjects were participants in the Nijmegen Growth Study." This study was a mixed longitudinal, interdisciplinary study of growth and development. Lateral cephalograms were obtained biannually between the ages of 9 and 14 years and annually between the ages of 7 and 9 years. A final set of records was also available at the age of 22 years. The cephalograms were collected under standardized conditions. Simultaneously with the celphalogramsl body height and other anthropometric data were collected. All subjects were white, had no physical abnormalities, and had not undergone orthodontic treatment. The subsample used consisted of 32 girls and 28 boys for whom 6 to 12 lateral cephalograms were available. To minimize the influence of biologic variability when considering growth rate, morphologic age was used instead of chronologic age. As a measure of morphologic age, the percentage of mature height was used, assuming that the mature body height (100%) was attained at the age of 22 years. The cephalograms were digitized according to the procedure published by Sluiter et al.'-" The following cephalometric landmarks were used in this study: skeletal landmarks of Nasion (N), point A (A), anterior nasal spine (ANS), pogonion (Pg), and menton (Me), and soft tissue landmarks (N'), subnasale (Sn), (Pg'). The definitions generally accepted in the international literature were used. From the digitized coordinates of the landmarks, six linear measurements were derived (Table I). The average growth rate of these dimensions was calculated for each person in the following way. For each person the linear measurements (Y-axis) were plotted against the perccntage of mature height (X axis). A straight line through these points was fitted with the method of least squares. The 509
51 0
Am. J. Orthod. Dentofac. Orthop.
t l o d z e l n , - R a k k e r et al.
June 1992
N - Ans,
facial length 70 mm A n 65
A n s - Me
16591 s
-
M
e (LFH)
60 (UFH) 55
N
-
A
75
80
r
t
s
50 45 40 I
70
I
1
t
I
I
I
85 90 95 100% Percentage bodylength
(Open bite) facial length 70 -ram
38531
6065 .
55
(LFH) Ans-Me N-Ans (UFH)
50 45 40 I
70
I
75
I
80
I
I
I
1
85 90 95 100% Percentage body length
(Deep bite) Dashed lines represent individual growth, continuous lines represent population means. Fig. 1. Illustrations of extremes. Average growth rate of the dimensions Na-Ans, Arts-Me for two boys
(broken lines). The straight lines are the means for the sample. The X axis represents the percentage of mature height; 100% is the height of the boys at the age of 22 years.
RESULTS
slope of this line was used as individual average growth rate relative to percentage of mature height (Fig. 1). Th'd'hy': pothesis that the growth of the upper and the lower anterior facial height show no correlation was tested with a one-sided test on the basis of the Kendall's "r test." Boys and girls were considered separately.
In Tables I, II, and III the descriptive statistics for boys and girls of the absolute and average growth rate of the six linear measurements are presented. To make sure that the presented material was representative of normal variation with respect to facial form, the lower
Volume 101 Number6
Vertical growth
511
Table I. Mean and standard deviation in millimeters of six linear measurements, four skeletal and two soft tissue measurements (Only age groups with more than 10 girls are shown)
Skeletal
Soft tissue
N-A
N-Ans
A-Pg
Ans-Me
Age
Mean l SD
Mean l SD
Atean l SD
Mean l SD
Mean
9.5 10.5 11.5 12.5 13.5 22.0
50.3 51.4 52.9 54.7 55.3 55.6
46.0 47.0 48.5 49.6 50.9 50.5
47.7 48.1 48.8 50.6 51.3 52.5
59.6 60.2 60.5 62.8 63.5 65.7
46.6 47.2 48.7 49.7 50.8 52.8
2.6 3.0 3.0 3.8 3.6 3.2
2.2 2.8 2.8 3.3 3.0 2.7
4.3 4.2 3.8 3.2 3.7 5.5
N'-Sn
3.2 3.2 3.4 3.5 3.3 5.1
Sn-Pg"
l SD
Mean l SD
3.0 3.5 3.8 4.0 3.1 3.4
46.0 44.8 46.0 47.8 49.9 50.0
4.3 4.8 4.0 3.7 2.9 4.4
Table II. Mean and standard deviation in millimeters of six linear measurements, four skeletal and two soft tissue measurements (Only age groups with more than 10 boys are shown)
Skeletal
Soft tissue
N-A
N-Arts
Age
Mean ] SD
Mean I SD
Mean
9.5 10.5 11.5 12.5 13.5 22.0
!52.5 53.8 55.6 58.4 59.5 61.7
48.0 49.1 50.7 53.3 54.7 56.1
47.3 47.7 48.7 49.5 52.4 54.8
3.3 3.2 4.0 4.1 4.5 4.0
A-Pg
2.8 3.1 3.4 3.6 3.7 3.8
[ SD
Table III. Average growth rate in millimeters per percentage of mature height
Girls
Measurement
Mean
N-A A-Pg
I
3.7 3.53.9 4.2 5.1 4.9
N'-Sn
Sn.Pg '
Mean [ SD
Mea,,
[ SD
59.8 60.7 61.6 62.7 64.9 69.3
50.'3 51.3 52.0 55.6 59.1 60.6
4.5 4.5 4.2 6.3 5.6 5.1
5.0 4.5 4.6 4.8 5.9 6.0
Mean [ SD 45.1 46.2 46.7 45.8 47.3 51.4
4.4 4.5 4.2 5.0 4.6 4.9
Table IV. Mean and standard deviation of lower
facial height (LFH) as a percentage of total anterior facial height (TAFH) for selected age groups
Boys I
Ans-Me
SD
Mean
SD
0.30 0.26
0.11 0.12
0.38 0.32
0.12 0.13
N-Ans Ans-Me
0.26 0.34
0.08 0.13
0.33 0.39
0.09 0. ! 2
N'-Sn Sn-Pg'
0.33 0.28
0.10 0.18
0.46 0.25
0.13 0.15
facial height (LFH) as a percentage of total anterior facial height (TAFH) was calculated (Table" IV). Plots of individual average growth velocity for a linear measurement of two different boys are given in (Fig. 1). Subjects, Nos. 16591 and 38531, show two different patterns of average growth rate for the dimensions N-Ans and Ans-Me. A negative correlation was found between the average growth rate of the upper and the lower anterior facial height (Table V). A further analysis showed that boys with a high percentage of LFH to TAFH exhibited
Girls
Boys
Age
Mean I
SD (%)
Mean I
(%)
(%)
SD (%)
9.5 10.5 11.5 12.5 13.5 22.0
57.6 57.2 56.5 56.7 56.5 57.3
2.2 2.5 2.4 2.7 2.1 2.6
56.6 56.4 55.8 55.0 55.2 55.9
2.7 2.8 2.8 2.3 2.5 2.7
(yr)
less growth changes in the upper facial height than in the lower facial height. Boys with a low percentage of LFH to TAFH exhibited larger growth changes in the upper facial height than-m the lower facial height. This was statistically significant. This could not be shown for girls (Table IV), although a trend towards a negative correlation was present. In Fig. 2 the smoothed curve represents graphically
512
Am. J. Orthod. Dentofac. Orthop.
L i g t h e h n - B a k k e r et al.
June
1992
growth difference 0.5
m/y
-
-
dl,
~
JL
0
. . . . . . . . .
~
_4. ~
_.',..*... ~ . . . . . . . . . . . . .
.~.- - ..A .....
1_
I
m
i
I
-0.5 521;
57~
62', 1; LFH
Difference in growth UFH-LFH vs. percentage LFH of TFH DoLLed lines bounds standard deviation region Fig. 2. Differences in rates of growth of upper and lower anterior facial height against percentage of lower facial height to total anterior facial height. The curve is the smoothed average growth velocity difference. The stars represent the individual differences. Dotted lines represent plus or minus one standard deviation.
the difference in rate of growth between the upper and the lower anterior facial height. The horizontal axis represents the lower facial height as a percentage of total facial height. The points are the individual measurements. The graph shows a negative tendency (
Vertical growth of the anterior face: A new approach A.S.W.M.R. Ligthelm-Bakker," E. Wattel, b I.H. Uljee, b and B. PrahI-Andersen" Amsterdam, The Netherlands
The mechanism of anterior vertical facial growth was studied in normal subjects between 7 and 22 years of age. This subsample (n = 60) of participants in the Nijmegen Growth Study was representative of normal variation with respect to vertical facial proportions. A negative correlation was found between the average growth rate of the upper and lower anterior facial height in boys. Boys with a relatively large.facial height exhibited a higher than average growth rate of the lower anterior facial height compared with the upper facial height. In girls a similar trend was present. The individual average growth rate of the anterior upper and lower facial height maintains or accentuates the early established facial form. (AM J ORTHOD DENTOFACORTHOP 1992;101:509-13.) D i f f e r e n t i a l growth of the upper and lower components I of the face seems to be important in the developmen! of different facial patterns. The development of subjects with open and deep bite faces have been studied in detail *,2 and subjects were found to grow differently. 2~ Subjects with deep bite faces show an increased upper anterior facial height, whereas increased lower anterior facial height is observed in subjects with open bite faces. Usually these dimensions of the face are studied cross-sectionally and from a morphologic point of view. Several authors 37 found that the total anterior facial height was relatively large in subjects with open bite faces and reduced in subjects with deep bite faces. The hypothesis that a key factor contributing to the open bite structure is a reduction in posterior facial height 3'4"8'9 was rejected by Nanda 2 and indirectly by Bj6rk ~~ and Fields et al. 7 In contrast to the former authors they found that ramal height is often excessive in subjects with open bite faces, and although anterior facial height demonstrated significant differences between different facial patterns, no significant differences in posterior facial height were found. These studies of the facial structure give little insight into the actual growth mechanisms of the face. Longitudinal data analysis is more meaningful in this respect. ''2 Because the postnatal facial growth changes are small with a relatively large variation, they are not easily observed when dealing with a crosssectional data set. Also, when analyzing the growth of children according to chronologic age, differences in general maturation or biologic age may add to the variation found. It could also be argued that instead of Supported in part by a grant from "'tier Prc',entiefonds," The tlague, The Netherlands. 'Department of Orthodontics, Academic Centre for. Dentist D' Amsterdam
(ACTA). *D,:partment of Mathematics, Vrije Universiteit Amsterdam. 8/1/27062
describing longitudinal changes in selected extreme facial types, 2 one should study the complete range of normal facial development to describe the growth mechanisms of the face. By doing this, the level of generalization is increased. The purpose of this study was to analyze the relationship between the rate of growth in uplSer and lower anterior facial height in normal children. MATERIAL AND METHODS
The subjects were participants in the Nijmegen Growth Study." This study was a mixed longitudinal, interdisciplinary study of growth and development. Lateral cephalograms were obtained biannually between the ages of 9 and 14 years and annually between the ages of 7 and 9 years. A final set of records was also available at the age of 22 years. The cephalograms were collected under standardized conditions. Simultaneously with the celphalogramsl body height and other anthropometric data were collected. All subjects were white, had no physical abnormalities, and had not undergone orthodontic treatment. The subsample used consisted of 32 girls and 28 boys for whom 6 to 12 lateral cephalograms were available. To minimize the influence of biologic variability when considering growth rate, morphologic age was used instead of chronologic age. As a measure of morphologic age, the percentage of mature height was used, assuming that the mature body height (100%) was attained at the age of 22 years. The cephalograms were digitized according to the procedure published by Sluiter et al.'-" The following cephalometric landmarks were used in this study: skeletal landmarks of Nasion (N), point A (A), anterior nasal spine (ANS), pogonion (Pg), and menton (Me), and soft tissue landmarks (N'), subnasale (Sn), (Pg'). The definitions generally accepted in the international literature were used. From the digitized coordinates of the landmarks, six linear measurements were derived (Table I). The average growth rate of these dimensions was calculated for each person in the following way. For each person the linear measurements (Y-axis) were plotted against the perccntage of mature height (X axis). A straight line through these points was fitted with the method of least squares. The 509
51 0
Am. J. Orthod. Dentofac. Orthop.
t l o d z e l n , - R a k k e r et al.
June 1992
N - Ans,
facial length 70 mm A n 65
A n s - Me
16591 s
-
M
e (LFH)
60 (UFH) 55
N
-
A
75
80
r
t
s
50 45 40 I
70
I
1
t
I
I
I
85 90 95 100% Percentage bodylength
(Open bite) facial length 70 -ram
38531
6065 .
55
(LFH) Ans-Me N-Ans (UFH)
50 45 40 I
70
I
75
I
80
I
I
I
1
85 90 95 100% Percentage body length
(Deep bite) Dashed lines represent individual growth, continuous lines represent population means. Fig. 1. Illustrations of extremes. Average growth rate of the dimensions Na-Ans, Arts-Me for two boys
(broken lines). The straight lines are the means for the sample. The X axis represents the percentage of mature height; 100% is the height of the boys at the age of 22 years.
RESULTS
slope of this line was used as individual average growth rate relative to percentage of mature height (Fig. 1). Th'd'hy': pothesis that the growth of the upper and the lower anterior facial height show no correlation was tested with a one-sided test on the basis of the Kendall's "r test." Boys and girls were considered separately.
In Tables I, II, and III the descriptive statistics for boys and girls of the absolute and average growth rate of the six linear measurements are presented. To make sure that the presented material was representative of normal variation with respect to facial form, the lower
Volume 101 Number6
Vertical growth
511
Table I. Mean and standard deviation in millimeters of six linear measurements, four skeletal and two soft tissue measurements (Only age groups with more than 10 girls are shown)
Skeletal
Soft tissue
N-A
N-Ans
A-Pg
Ans-Me
Age
Mean l SD
Mean l SD
Atean l SD
Mean l SD
Mean
9.5 10.5 11.5 12.5 13.5 22.0
50.3 51.4 52.9 54.7 55.3 55.6
46.0 47.0 48.5 49.6 50.9 50.5
47.7 48.1 48.8 50.6 51.3 52.5
59.6 60.2 60.5 62.8 63.5 65.7
46.6 47.2 48.7 49.7 50.8 52.8
2.6 3.0 3.0 3.8 3.6 3.2
2.2 2.8 2.8 3.3 3.0 2.7
4.3 4.2 3.8 3.2 3.7 5.5
N'-Sn
3.2 3.2 3.4 3.5 3.3 5.1
Sn-Pg"
l SD
Mean l SD
3.0 3.5 3.8 4.0 3.1 3.4
46.0 44.8 46.0 47.8 49.9 50.0
4.3 4.8 4.0 3.7 2.9 4.4
Table II. Mean and standard deviation in millimeters of six linear measurements, four skeletal and two soft tissue measurements (Only age groups with more than 10 boys are shown)
Skeletal
Soft tissue
N-A
N-Arts
Age
Mean ] SD
Mean I SD
Mean
9.5 10.5 11.5 12.5 13.5 22.0
!52.5 53.8 55.6 58.4 59.5 61.7
48.0 49.1 50.7 53.3 54.7 56.1
47.3 47.7 48.7 49.5 52.4 54.8
3.3 3.2 4.0 4.1 4.5 4.0
A-Pg
2.8 3.1 3.4 3.6 3.7 3.8
[ SD
Table III. Average growth rate in millimeters per percentage of mature height
Girls
Measurement
Mean
N-A A-Pg
I
3.7 3.53.9 4.2 5.1 4.9
N'-Sn
Sn.Pg '
Mean [ SD
Mea,,
[ SD
59.8 60.7 61.6 62.7 64.9 69.3
50.'3 51.3 52.0 55.6 59.1 60.6
4.5 4.5 4.2 6.3 5.6 5.1
5.0 4.5 4.6 4.8 5.9 6.0
Mean [ SD 45.1 46.2 46.7 45.8 47.3 51.4
4.4 4.5 4.2 5.0 4.6 4.9
Table IV. Mean and standard deviation of lower
facial height (LFH) as a percentage of total anterior facial height (TAFH) for selected age groups
Boys I
Ans-Me
SD
Mean
SD
0.30 0.26
0.11 0.12
0.38 0.32
0.12 0.13
N-Ans Ans-Me
0.26 0.34
0.08 0.13
0.33 0.39
0.09 0. ! 2
N'-Sn Sn-Pg'
0.33 0.28
0.10 0.18
0.46 0.25
0.13 0.15
facial height (LFH) as a percentage of total anterior facial height (TAFH) was calculated (Table" IV). Plots of individual average growth velocity for a linear measurement of two different boys are given in (Fig. 1). Subjects, Nos. 16591 and 38531, show two different patterns of average growth rate for the dimensions N-Ans and Ans-Me. A negative correlation was found between the average growth rate of the upper and the lower anterior facial height (Table V). A further analysis showed that boys with a high percentage of LFH to TAFH exhibited
Girls
Boys
Age
Mean I
SD (%)
Mean I
(%)
(%)
SD (%)
9.5 10.5 11.5 12.5 13.5 22.0
57.6 57.2 56.5 56.7 56.5 57.3
2.2 2.5 2.4 2.7 2.1 2.6
56.6 56.4 55.8 55.0 55.2 55.9
2.7 2.8 2.8 2.3 2.5 2.7
(yr)
less growth changes in the upper facial height than in the lower facial height. Boys with a low percentage of LFH to TAFH exhibited larger growth changes in the upper facial height than-m the lower facial height. This was statistically significant. This could not be shown for girls (Table IV), although a trend towards a negative correlation was present. In Fig. 2 the smoothed curve represents graphically
512
Am. J. Orthod. Dentofac. Orthop.
L i g t h e h n - B a k k e r et al.
June
1992
growth difference 0.5
m/y
-
-
dl,
~
JL
0
. . . . . . . . .
~
_4. ~
_.',..*... ~ . . . . . . . . . . . . .
.~.- - ..A .....
1_
I
m
i
I
-0.5 521;
57~
62', 1; LFH
Difference in growth UFH-LFH vs. percentage LFH of TFH DoLLed lines bounds standard deviation region Fig. 2. Differences in rates of growth of upper and lower anterior facial height against percentage of lower facial height to total anterior facial height. The curve is the smoothed average growth velocity difference. The stars represent the individual differences. Dotted lines represent plus or minus one standard deviation.
the difference in rate of growth between the upper and the lower anterior facial height. The horizontal axis represents the lower facial height as a percentage of total facial height. The points are the individual measurements. The graph shows a negative tendency (
