The purpose of this study was to investigate maxillary and mandibular transverse growth in untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18.

1. ORIGINAL ARTICLE
Transverse growth of the maxilla and mandible
in untreated girls with low, average, and high
MP-SN angles: A longitudinal study
Dawn M. Wagnera
and Chun-Hsi Chungb
Philadelphia, Pa
Introduction: The purpose of this study was to investigate maxillary and mandibular transverse growth in
untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18.
Methods: Eighty-one untreated white girls with low (Յ 27°, n ϭ 16), average (Ͼ 27° to Ͻ 37°, n ϭ 41), and
high (Ն 37°, n ϭ 24) mandibular plane angles at age 6 were selected from the Bolton-Brush and Burlington
Growth Studies. For each subject, longitudinal posteroanterior cephalograms at different ages (from ages 6
to 18) were traced, and the widths of maxilla and mandible were measured. All the measurements were
converted by using a magnification factor of 8.5% (the subject-to-film distance was set at 13 cm). Results:
At age 6, the high-angle group had narrower maxillary and mandibular widths than the low-angle group, and
this trend continued until age 18. From ages 6 to 14, maxillary width showed a steady and similar rate of
increase for all 3 groups (0.90-0.95 mm per year), yet a plateau was reached at age 14 for all groups.
Mandibular width increased at a steady rate (about 1.6 mm/year) for all 3 groups until age 14, and a plateau
was reached for the high-angle group. For the low- and average-angle groups, mandibular growth continued
from ages 14 to 18 but at a slower rate (0.85 mm and 0.39 mm per year, respectively). Conclusions: Vertical
facial patterns (with low or high mandibular plane angles) might play a strong role in the transverse growth
of the maxilla and the mandible. (Am J Orthod Dentofacial Orthop 2005;128:716-23)
I
t is well known that, during growth, the changes in
size and shape of the facial bones are determined
by sutural, cartilagenous, and periosteal and en-
dosteal bone deposition and resorption (remodeling).1
Soft tissues relating to the bones and functional needs
are believed to play an important role in the remodeling
process.1-5
The influence of jaw muscles on facial form has
intrigued many investigators. Finn6
reported that max-
imum biting force in the molar region was greater in
brachyfacial (short-face) subjects than in dolichofacial
(long face) subjects. Proffit et al7
found that long-face
adults have significantly less occlusal force during
maximum-effort, simulated chewing and swallowing
than do subjects with normal vertical facial dimensions.
Christie8
evaluated orthodontic records of 82 white
adults (43 women, 39 men) with normal untreated
occlusions and found that short-face men had greater
maxillary and mandibular widths than normal men.
However, no differences in width were found between
short-face and normal women. They did not provide
data on long-face subjects because the sample size was
too small (only 4). Weijs and Hillen9
and van Sprosen
et al10
found that the cross-sectional areas of the
temporalis and masseter muscles correlated positively
with facial width. They suggested that the jaw muscles
affect facial growth and partly determine the final facial
dimensions. Kiliaridis11
also suggested that the increased
loading of the jaws from masticatory muscle hyperfuction
might lead to increased sutural growth and bone apposi-
tion, resulting in increased transversal growth of the
maxilla and broader bone bases for the dental arches.
Tsunori et al12
reported that, when compared with
average and long-face persons, short-face subjects had
larger intermolar widths and greater buccal cortical
bone thicknesses in the molar area of the mandible.
They suggested a possible link between the develop-
ment of the maxillofacial complex in the vertical and
transverse dimensions and measures of increased mus-
cularity.
Clinicians often pay much attention to the inclina-
tion of the mandibular plane, because it is a major
determinant of the vertical dimension of a face (long,
average, or short). A person with a steeper mandibular
plane to cranial base (larger MP-SN angle) often has a
From the Department of Orthodontics, School of Dental Medicine, University
of Pennsylvania, Philadelphia.
a
Former orthodontic resident; US Air Force.
b
Associate professor.
Reprint requests to: Dr Chun-Hsi Chung, Department of Orthodontics, Univer-
sity of Pennsylvania School of Dental Medicine, Robert Schattner Center,
240 S 40th St, Philadelphia, PA 19104-6030; e-mail, chunc@pobox.upenn.edu.
Submitted, May 2004; revised and accepted, September 2004.
0889-5406/$30.00
Copyright © 2005 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2004.09.028
716

2. long anterior facial height, a smaller ratio of posterior
to anterior facial height, and a short mandibular ramus
height. Conversely, a person with a flat mandibular
plane (smaller MP-SN angle) has a short anterior facial
height, a larger ratio of posterior to anterior facial
height, and a long mandibular ramus height.13-16
The
purpose of this study was to investigate the maxillary
and mandibular transverse growth in untreated female
subjects with low, average, and high MP-SN angles
longitudinally from ages 6 to 18.
MATERIAL AND METHODS
The sample consisted of 81 white girls, including
31 from the Bolton-Brush Growth Study at Case
Western Reserve University in Cleveland, Ohio, and 50
from the Burlington Growth Centre at the University of
Toronto in Canada. The subjects were selected based
on the following criteria: (1) lateral and posteroanterior
(PA) cephalograms available at about age 6 and longi-
tudinal PA cephalograms available every 1-3 years to
about age 18, (2) ANB angle between 0° and 5° at age
6, (3) normal maxillary and mandibular arch forms
without anterior or posterior crossbite, (4) in good
health with no history of head or facial trauma, steroid
or growth-hormone therapy, or orthodontic treatment.
The definitions of the landmarks of the PA and
lateral cephalograms corresponded to those given by
Ricketts et al17
and Riolo et al.18
For each subject, the
lateral cephalogram about age 6 was traced by hand on
acetate paper by an examiner (D.M.W.), and the SNA,
SNB, ANB, and MP-SN angles were measured (Fig 1).
MP was defined as a line drawn from menton to the
inferior border of the angular area of the mandible.13,15,16
The sample was divided into 3 groups according to
the MP-SN angles at age 6: (1) low angle (Յ 27°,
n ϭ 16), (2) average angle (Ͼ27° to Ͻ37°, n ϭ 41), and
(3) high angle (Ն 37°, n ϭ 24). These MP-SN values
represented about 1 SD from the mean MP-SN angle of
children aged 8 to 11 reported by Riedel.19
The mean
Fig 1. Hand-traced lateral cephalogram of subject at
age 6. SNA, SNB, ANB, and MP-SN angles were
measured.
Fig 2. Jugale (J): at jugal process, intersection of out-
line of tuberosity of maxilla and zygomatic buttress; and
antegonion (Ag): at antegonial notch, lateral inferior
margin of antegonial protuberances.
Table I. Group descriptions at about age 6
Groups n
Mean
ANB (°)
Range
(°)
Mean
MP-SN (°)
Range
(°)
Low-angle 16 2.19 0-5 26.19 21-27
Average-angle 41 3.44 1-5 33.37 30-36
High-angle 24 3.33 1-5 38.70 37-44
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 128, Number 6
Wagner and Chung 717

3. MP-SN angles at about age 6 were 26.19° for the
low-angle group, 33.37° for the average-angle group,
and 38.70° for the high-angle group (Table I). The
mean ANB angles were 2.19° (low angle), 3.44°
(average angle), and 3.33° (high angle) (Table I).
Each subject’s PA cephalogram for each age was
traced on acetate paper by an examiner (D.M.W.).
The following landmarks were identified: jugale (J),
at the jugal process, the intersection of the outline of
the tuberosity of the maxilla and the zygomatic
buttress; and antegonion (Ag), at the antegonial notch,
the lateral inferior margin of the antegonial protuber-
ances (Fig 2).17
The distances of J-J, and Ag-Ag were
measured with a digital caliper (Orthopli, Philadelphia,
Pa), accurate to 0.01 mm.
Because subjects from 2 growth studies were ex-
amined, all linear measurements had to be converted
because of different enlargement factors for each
cephalostat. At the Burlington Growth Centre, all PA
cephlaograms, regardless of the subject’s age, were
magnified by 9.84%. The anode-to-subject distance and
the film-to-porionic axis distance (FPD) were set at
152.4 cm and 15 cm, respectively.20
In the Bolton-
Brush Growth Study, magnification was regulated ac-
cording to the subject’s age (age 6-7, 7.2%; age 8,
7.4%; age 9-10, 7.5%, age 11, 7.7%; age 12, 7.9%; age
13, 8.0%; age 14, 8.1%; age 15-16, 8.2%; age 17-18,
8.4%).21
Because 13 cm is commonly used in American
institutions and practices as the FPD, all J-J and Ag-Ag
values were converted to the recommended distance of 13
cm FDP with a magnification factor of 8.5%.22
In addition, 6 subjects were randomly selected, and
their PA cephalograms for each age (total, 39 films)
were retraced and remeasured by the same examiner
(D.M.W.) to assess whether any intraexaminer error
resulted from landmark selection, tracing, and measure-
ment error. The same measurements were made in the
subjects to be studied. Also, 6 subjects were randomly
chosen, and their PA cephalograms for each age (total,
47 films) were traced and measured by another exam-
iner to determine the interexaminer reliability. Pearson
correlation analysis and the paired Student t test were
conducted for all first and second linear and angular
measurements to determine whether they were signifi-
Table II. Transverse maxillary growth (mm) from ages 6 to 18 for low average- and high-angle groups and statistical
significance between groups; measurements calculated based on 13-cm subject-to-film distance with magnification
of 8.5%
Age
Low-angle group Average-angle group High-angle group P value
n J-J SD n J-J SD n J-J SD L vs A A vs H L vs H
6 11 57.47 1.88 36 56.66 2.73 19 55.74 2.38 0.14 0.10 0.02*
7 7 58.66 1.26 23 57.99 2.7 14 56.6 2.06 0.19 0.04* 0.01*
8 9 59.77 1.61 26 59.57 2.45 19 57.35 1.66 0.39 0.00* 0.00*
9 12 60.75 2.2 40 60.95 2.63 21 58.46 2.23 0.40 0.00* 0.00*
10 10 62.8 2.16 34 62.26 2.74 19 59.67 1.96 0.26 0.00* 0.00*
11 10 63.74 2.93 27 63.18 2.62 16 61.1 2.46 0.30 0.01* 0.01*
12 16 63.52 2.87 45 63.09 2.55 22 61.23 2.77 0.30 0.01* 0.01*
13 10 64.4 2.34 30 63.9 2.56 16 62.52 2.73 0.29 0.05* 0.04*
14 16 64.15 2.15 38 64.21 2.46 23 62.1 2.63 0.46 0.00* 0.01*
15 6 64.79 2.32 18 64.09 2.56 4 61.63 1.3 0.27 0.01* 0.01*
16 15 64.41 1.9 35 64.3 2.49 23 62.3 3.07 0.43 0.01* 0.01*
17 5 64.53 2.92 19 64.26 2.96 11 61.61 2.83 0.43 0.01* 0.05*
18 5 64.57 3.15 17 63.6 2.42 10 61.79 3.36 0.28 0.08 0.08
J, jugale; L, low angle; A, average angle; H, high angle.
*Statistically significant.
Table III. Predicted transverse maxillary growth (mm)
from regression analysis of data in Table II
Age
Predicted J-J
Low-angle Average-angle High-angle
6 58.07 57.50 55.85
7 58.97 58.45 56.74
8 59.88 59.41 57.63
9 60.79 60.36 58.53
10 61.70 61.31 59.42
11 62.60 62.27 60.31
12 63.51 63.22 61.21
13 64.42 64.17 62.10
14 65.32 65.13 62.99
15 65.38 65.02 62.93
16 65.44 64.92 62.86
17 65.50 64.81 62.80
18 65.56 64.71 62.74
J, jugale.
American Journal of Orthodontics and Dentofacial Orthopedics
December 2005
718 Wagner and Chung

4. cantly different. The significance of differences was
predetermined at P Ͻ .05.
The mean and standard deviation for J-J and Ag-
Ag, and the ratio of J-J to Ag-Ag from ages 6 to 18
were computed, and the regression analysis was per-
formed. The differences of each variable between the
groups were tested with the Student 2-tailed t test. The
significance of differences was predetermined at P Ͻ .05.
RESULTS
The intraexaminer reliability measurement showed
a high correlation, with r ϭ 0.96 and r ϭ 0.99 between
repeated measurements for J-J and Ag-Ag, respec-
tively. Interexaminer reliability showed a high correla-
tion, with r ϭ 0.91 and r ϭ 0.95 between repeated
measurements for J-J and Ag-Ag, respectively.
Table II shows the longitudinal maxillary width
(J-J) of each group and statistical data between the
groups from ages 6 to 18. Table III and Figure 3
represent the predicted longitudinal width of the max-
illa determined from a regression analysis of the data in
Table II. The maxillary width in the low-angle group
was 57.47 mm at age 6 and increased to 64.57 mm by
age 18. The J-J of the average-angle group was 56.66
mm at age 6 and increased to 63.60 mm at age 18, and
the high-angle group was 55.74 mm at age 6 and 61.79
mm at age 18. A steady width increase was seen from
ages 6 to 14; then a plateau was seen until age 18 for all
3 groups. From ages 6 to14, the growth rates were 0.90
mm per year for the low- and high-angle groups and
0.95 mm for the average-angle group.
Table IV shows the longitudinal mandibular width
(Ag-Ag) from ages 6 to 18. Table V and Figure 4
represent the predicted Ag-Ag determined from a
regression analysis of the data in Table IV. The growth
of Ag-Ag in the low-angle group displayed a steady
increase from 73.50 mm at age 6 to 85.74 mm at age
14—a rate of 1.57 mm per year—and then a slower rate
(0.85 mm per year) from ages 14 to 18. In the
average-angle group, Ag-Ag was 72.87 mm at age 6
and increased to 85.36 mm at age 14. A steady increase
was noted from ages 6 to 14 at a rate of 1.55 mm per
year, and then a decrease in rate (0.39 mm) was noted
from ages 14 to 18. The high-angle group started at
72.18 mm at age 6 and increased to 84.81 mm at age
14. A steady increase was noted from ages 6 to 14 at a
rate of 1.57 mm per year, and then a plateau was seen
from ages 14 to 18.
Table VI shows the annual ratio of J-J to Ag-Ag
from ages 6 to 18. Table VII and Figure 5 represent the
predicted ratio values generated from a regression
analysis of the data in Table VI. The ratio generally
decreased as the ages of subjects increased. In the
high-angle group, there was a plateau in the ratio from
ages 14 to 18. The ratio tended to be smaller in the
high-angle group than in the other groups.
DISCUSSION
We examined only untreated girls because male and
female subjects have different sizes in all 3 dimen-
sions.15,16,23,24
Unfortunately, many previous studies,
in their measurements of linear transverse dimension,
combined male and female subjects.17,22,25
Our sample
included 16 low-angle, 41 average-angle, and 24 high-
angle girls. We gathered all information available at the
Bolton-Brush and Burlington growth studies for each
untreated patient used in this study. Because of limited
records, we found only 16 low-angle subjects.
Because of different magnification factors, a direct
comparison could not be made between cephalograms
Fig 3. Predicted transverse maxillary growth (J-J) of low-, average-, and high-angle groups from
ages 6 to 18.
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 128, Number 6
Wagner and Chung 719

5. taken at a different FPD. To eliminate this factor, we
corrected the values of J-J and Ag-Ag to the recom-
mended standard of 13 cm FPD with a magnification of
8.5%.22
If clinicians desire to compare their PA ceph-
alometric values to our data, they must first confirm that
the FPD is the same before a valid comparison can be
made. We suggest that the FPD is required in reporting
any linear cephalometric measurement; it is lacking in
some reports.17,23,25,26
In our study, the maxilla had a steady transverse
growth rate from ages 6 to 14, but there was little or no
growth after 14 years in all groups. Similar findings
were reported by Cortella et al.27
Snodell et al26
showed that maxillary growth was complete for most of
his female subjects by age 15. The Rocky Mountain
analysis of Ricketts et al,17
commonly used for diag-
nosis of transverse dimensions of the maxilla and
mandible, showed steady growth from ages 9 to 16.
Yet, he did not separate his norms for boys and girls.
For the mandible, we found steady growth from ages 6
to 14 for all groups. But after 14, some differences were
noted. For the high-angle group, no more increase in
Ag-Ag was found, but the average-angle and low-angle
groups continued to grow to age 18. Snodell et al26
showed that girls’ mandibular growth continued until
age 18. Differently, Krogman28
suggested that growth
in the width of both jaws tends to be completed before
the adolescent growth spurt and is affected minimally
by adolescent growth changes.
In this study, little or no growth spurt was demon-
strated in J-J and Ag-Ag for all groups. Thus, a
regression analysis was performed, and the rate of
growth was determined for each group. For the maxilla,
from ages 6 to 14, we found a similar rate of
transverse growth (0.90-0.95 mm per year) for all
groups. Differently, Ricketts et al17
reported 0.6 mm
per year in J-J from ages 9 to 16. With implants,
Björk and Skieller29,30
reported maxillary transverse
growth of 0.4 mm/year in 9 boys between 4 and 20
years of age. Korn and Baumrind31
also studied trans-
verse maxillary development longitudinally with im-
plants in the zygomatic regions. They reported a mean
transverse maxillary growth of 0.38 mm per year in
girls from ages 8.5 to 10.5 or 15.5 years. For the
mandible, our data showed that Ag-Ag had a general
Table IV. Transverse mandibular growth (mm) from ages 6 to 18 for low- average- and high-angle groups and
statistical significance between groups; measurements calculated based on 13-cm subject-to-film distance with
magnificantion of 8.5%
Age
Low-angle group Average-angle group High-angle group P value
n Ag-Ag SD n Ag-Ag SD n Ag-Ag SD L vs A A vs H L vs H
6 11 73.50 3.65 36 72.87 3.79 19 72.18 2.41 0.31 0.21 0.15
7 7 77.20 2.48 23 74.80 4.05 14 74.40 3.85 0.04* 0.38 0.03*
8 9 78.57 2.47 26 76.94 3.78 19 76.27 2.69 0.08 0.25 0.02*
9 12 79.33 3.6 40 78.53 3.88 21 77.97 3.01 0.26 0.27 0.14
10 10 82.26 2.68 34 80.05 4.28 19 78.84 2.58 0.03* 0.10 0.00*
11 10 83.28 3.31 27 81.40 4.25 16 80.61 3.54 0.09 0.26 0.03*
12 16 84.08 3.79 45 82.82 3.93 22 82.58 3.33 0.13 0.40 0.11
13 10 86.42 3.53 30 84.29 3.98 16 84.02 3.95 0.06 0.42 0.06
14 16 85.74 3.77 38 85.36 3.76 23 84.81 3.89 0.37 0.30 0.23
15 6 85.73 2.65 18 86.21 4.47 4 83.88 4.29 0.38 0.19 0.24
16 15 87.11 3.69 35 85.95 3.75 23 85.59 3.41 0.16 0.35 0.11
17 5 87.75 3.8 19 86.53 4.66 11 83.60 3.12 0.28 0.02* 0.04*
18 5 89.01 3.11 17 87.15 4.14 10 84.43 4.83 0.15 0.08 0.02*
Ag, antegonion; L, low angle; A, average angle; H, high angle.
*Statistically significant.
Table V. Predicted transverse mandibular growth (mm)
from regression analysis of data in Table IV
Age
Predicted Ag-Ag
Low-angle Average-angle High-angle
6 75.05 73.47 72.77
7 76.57 75.02 74.34
8 78.10 76.57 75.92
9 79.63 78.12 77.50
10 81.15 79.67 79.08
11 82.68 81.22 80.65
12 84.21 82.78 82.23
13 85.73 84.33 83.81
14 87.26 85.88 85.38
15 88.12 86.27 85.28
16 88.97 86.66 85.18
17 89.83 87.05 85.07
18 90.68 87.44 84.97
Ag, antegonion.
American Journal of Orthodontics and Dentofacial Orthopedics
December 2005
720 Wagner and Chung

6. increase from ages 6 to 14 at a rate of 1.6 mm per year
for all 3 groups. However, after age 14, there were
differences between the groups. From ages 14 to 18, the
low-angle group had an increase of 0.85 mm per year,
the average-angle group had a slower rate of growth of
0.39 mm per year, and the high-angle group showed no
growth. Ricketts et al17
reported that, from ages 9 to 16,
the increase of Ag-Ag was 1.4 mm per year. Snodell et
al26
reported an average of 1.3 mm per year increase in
the width of the mandible when measuring from the
most lateral margin of the angle of the mandible.
Regardless of the groups, in our study, the growth in
mandibular width seemed to be different from that of
the maxilla because Ag-Ag continued to increase past
age 14 in the low-angle and average-angle groups.
The use of a ratio in a PA cephalometric study is
Fig 4. Predicted transverse mandibular growth (Ag-Ag) of low-, average-, and high-angle groups
from ages 6 to 18.
Table VI. Ratio of J-J to Ag-Ag from ages 6 to 18 in low-, average-, and high-angle groups and statistical significance
between groups
Age
Low-angle group Average-angle group High-angle group P value
n J-J/Ag-Ag SD n J-J/Ag-Ag SD n J-J/Ag-Ag SD L vs A A vs H L vs H
6 11 0.784 0.047 36 0.779 0.051 19 0.773 0.036 0.40 0.29 0.26
7 7 0.760 0.025 23 0.777 0.054 14 0.762 0.037 0.13 0.16 0.45
8 9 0.761 0.019 26 0.776 0.046 19 0.752 0.026 0.10 0.02* 0.17
9 12 0.767 0.035 40 0.776 0.039 21 0.750 0.033 0.22 0.00* 0.10
10 10 0.764 0.026 34 0.779 0.042 19 0.757 0.03 0.09 0.02* 0.28
11 10 0.766 0.035 27 0.778 0.043 16 0.759 0.037 0.20 0.07 0.31
12 16 0.757 0.043 45 0.763 0.039 22 0.743 0.034 0.29 0.02* 0.15
13 10 0.746 0.032 30 0.759 0.040 16 0.745 0.033 0.15 0.10 0.47
14 16 0.749 0.037 38 0.753 0.039 23 0.733 0.031 0.37 0.02* 0.08
15 6 0.756 0.034 18 0.745 0.040 4 0.737 0.048 0.25 0.38 0.25
16 15 0.740 0.032 35 0.750 0.039 23 0.728 0.03 0.20 0.01* 0.13
17 5 0.736 0.035 19 0.744 0.046 11 0.738 0.037 0.33 0.33 0.47
18 5 0.726 0.033 17 0.731 0.033 10 0.733 0.042 0.21 0.16 0.36
J, jugale; Ag, antegonion; L, low angle; A, average angle; H, high angle.
*Statistically significant.
Table VII. Predicted ratio of J-J to Ag-Ag from regres-
sion analysis of data in Table VI
Age
Predicted J-J/Ag-Ag
Low-angle Average-angle High-angle
6 0.774 0.783 0.768
7 0.771 0.780 0.764
8 0.768 0.777 0.760
9 0.765 0.774 0.756
10 0.762 0.771 0.753
11 0.758 0.768 0.749
12 0.755 0.765 0.745
13 0.752 0.762 0.742
14 0.749 0.759 0.738
15 0.742 0.755 0.738
16 0.735 0.750 0.738
17 0.729 0.746 0.738
18 0.722 0.741 0.738
J, jugale; Ag, antegonion.
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 128, Number 6
Wagner and Chung 721

7. advantageous because the results can be compared with
other subjects or groups whose radiographs have been
taken with uncontrolled enlargement of the various
skull structures on a x-ray film. The results of our study
demonstrate that the J-J/Ag-Ag ratios were smaller than
the Rocky Mountain norms of Ricketts et al17
at all
ages. There is a general trend of ratio decrease from
ages 6 to 18 in the low- and average-angle groups. For
the high-angle group, the ratio decreased from ages 6 to
14 and then a plateau was seen.
Our data clearly showed the significant differences
among the high-, average-, and low-angle groups in the
growth of J-J and Ag-Ag. This might indicate that
different facial morphological patterns (short or long
face) play a strong role in the growth and basic
configuration of the maxillary and mandibular apical
bases as suggested by Enlow and Hans.1
CONCLUSIONS
The following conclusions can be made from this
study:
1. At age 6, the high-angle group had smaller maxil-
lary (J-J) and mandibular (Ag-Ag) widths than the
low-angle group. This trend was consistent until
age 18 years.
2. Maxillary transverse growth (J-J) increased at a
similar rate of 0.90 to 0.95 mm per year from ages
6 to 14 for all 3 groups. There was little or no more
maxillary transverse growth after age 14.
3. Mandibular transverse growth (Ag-Ag) increased at
a steady rate (1.6 mm/year) for the low-, average-,
and high-angle girls until age 14. A plateau at age
14 was noted for the high-angle group, and contin-
ued growth was seen in the low- and average-angle
groups until age 18 (0.85 mm and 0.39 mm per
year, respectively).
4. Vertical facial patterns (with low or high MP-SN
angles) might play a strong role in the transverse
growth of the maxilla and the mandible.
We thank Drs Seong Han and Solomon Katz for
their help.
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Editors of the International Journal of Orthodontia (1915-1918),
International Journal of Orthodontia & Oral Surgery (1919-1921),
International Journal of Orthodontia, Oral Surgery and Radiography (1922-1932),
International Journal of Orthodontia and Dentistry of Children (1933-1935),
International Journal of Orthodontics and Oral Surgery (1936-1937), American
Journal of Orthodontics and Oral Surgery (1938-1947), American Journal of
Orthodontics (1948-1986), and American Journal of Orthodontics and Dentofacial
Orthopedics (1986-present)
1915 to 1932 Martin Dewey
1931 to 1968 H. C. Pollock
1968 to 1978 B. F. Dewel
1978 to 1985 Wayne G. Watson
1985 to 2000 Thomas M. Graber
2000 to present David L. Turpin
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 128, Number 6
Wagner and Chung 723