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Transverse Growth of Maxilla and Mandible
Ram Nanda, Stephen F. Snodell, and Prashanti Bollu
Growth in the transverse plane has not received due emphasis in the
diagnosis of craniofacial and dentoalveolar anomalies. Because the research
focus has largely been on sagittal and vertical planes of the face, inferences
on normal and abnormal growth patterns have been limited to these planes.
This article is based on a section of the extensive research done on growth
and development of dentofacial structures at the University of Oklahoma.
Nine transverse craniofacial and dentoalveolar measurements were made
on anteroposterior radiographs of 25 male and 25 female subjects between
the ages of 6 and 18 years. The average measurements at each age are
presented. Regression models suggest a strong prediction of adult size at
age 12. Large prospective longitudinal studies using regression models are
needed to validate this evidence. (Semin Orthod 2012;18:100-117.) © 2012
Elsevier Inc. All rights reserved.
rowth of the human face is a multidimensional and dynamic continuum. To measure and interpret the incremental changes occurring during growth, the use of appropriate
diagnostic tools is paramount. A comprehensive analysis of craniofacial growth includes
monitoring growth changes in all 3 planes of
space, that is, transverse, sagittal and vertical.
Each plane offers unique information on the
extent and direction of growth status, ultimately
aiding in the overall treatment planning. Transverse growth changes shed light on dentofacial
asymmetries, expanded/constricted jaws, and
dental crossbites. The sagittal or anteroposterior
(AP) dimension offers a great deal of information on facial profile, arch length discrepancies,
and excessive/inadequate overjets. Vertical
growth patterns allow visualizing facial proportions, deep bites, and open bites.
G
Professor Emeritus, Department of Orthodontics, College of Dentistry, University of Oklahoma, Oklahoma City, OK; Orthodontist,
Private Practice, Cedar Park, TX; Orthodontic Resident, College of
Dental Medicine, Roseman University of Health Sciences, Henderson, NV.
Address correspondence to Ram Nanda, BDS, DDS, MS, PhD,
Department of Orthodontics, College of Dentistry, University of
Oklahoma, 7600 Dorset Drive, Oklahoma City, OK 73116.
E-mail: [email protected]
© 2012 Elsevier Inc. All rights reserved.
1073-8746/12/1802-0$30.00/0
doi:10.1053/j.sodo.2011.10.007
100
The timing of orthodontic intervention is often challenging to even the most experienced
practitioners. A good understanding is needed
on the growth of jaws, including the total
amount of growth, timing of growth spurts, and
cessation or near completion of growth. Many
longitudinal growth studies have been done to
measure these incremental changes and to develop normative values. Although it is important
to note that individual variations exist, these
norms serve as a useful guide for the clinician in
the overall decision process.
An invaluable aid in the proper diagnosis and
orthodontic treatment planning of a growing
child is the ability to predict future growth potential. Assessment of growth potential requires
a thorough knowledge on the extent and sequence of growth completion. Although development and maturation continue throughout
life, growth reaches its maximum potential at a
certain age. In assessing the completion of
craniofacial growth, it is important to note that
growth in all 3 dimensions does not stop at the
same time. Several longitudinal studies have attempted to identify the age at near completion
of growth of the jaws. More congruence exists on
the sequence of growth patterns than the age at
which maximum growth is achieved. Growth follows the sequential completion of cranium followed by facial width (transverse), then facial
depth (sagittal), and lastly height (vertical).1 Al-
Seminars in Orthodontics, Vol 18, No 2 (June), 2012: pp 100-117
Transverse Growth of Maxilla and Mandible
though AP and vertical growth continue well
into adulthood, Class II, Class III relations and
relapse of deep bites and open bites are often
seen.2 These continued structural changes are
also responsible for deterioration of occlusal relationships and the relapse of malocclusion after
completion of orthodontic treatment.3
Interestingly, facial width, the largest facial
dimension at infancy, shows the least relative
growth rate compared with the facial depth and
height.4 Transverse growth is found to achieve
near completion by late adolescence; however,
sagittal and vertical growth continue well into
adulthood. Recent research, however, contests
this accepted phenomenon on sequential completion and shows evidence of overlap in 3 dimensions, indicating that although growth of
some transverse dimensions, such as cranial and
interjugal width, end much before AP and vertical growth, interzygomatic and intergonial
widths continue to increase well into adulthood.5 Careful attention to these details is important in effective orthodontic treatment management, especially during the retention period
to control for the effects of late growth changes.
Developing an effective orthodontic diagnostic workup is a challenging process. Several
cephalometric radiographic analyses developed
over the years assist the clinician in diagnosing
transverse relationships between jaws. The
Rocky Mountain analysis6 and the Ricketts analysis7 are among the most popular and widely
used cephalometric analyses. These analyses,
however, represent a certain demographic profile, and hence, caution must be applied in using
them as true norms.
Annual growth increments assist in measuring the growth extent and rate. Various landmarks have been used to monitor growth increments. Transverse craniofacial measurements
include widths of cranial, facial, nasal, maxillary,
and mandibular structures. The use of interjugal
distance (bijugale) in measuring maxillary width
has been validated by previous studies.8-10 Mandibular width, however, has been measured using the distance between gonions10 and antegonial notches.8,11 Hesby et al9 measured both
intergonial and interantegonial distances. Dental arch dimensions change gradually as a result
of growth and as a result of orthodontic treatment. These changes in the transverse plane are
typically measured at the intercanine, interpre-
101
molar, and intermolar regions of the maxilla as
well as the mandible.
To measure transverse growth changes in the
dentoalveolar structures of upper and lower
jaws, previous studies used dental casts, whereas
more recent studies used posteroanterior (PA)
views. Arch width measurements are usually
taken at the intercanine, interpremolar, and intermolar areas of the maxilla and mandible.
Some studies recorded the intermolar distances
at first as well as second molars. Different methods have been used in measuring these widths.
For instance, intermolar width measurements
were done between bilateral gingival points of
first molars,9 central fossae of maxillary first
molars, and distobuccal cusp tips of mandibular first molars.12,13 Other studies used the
most prominent lateral points on buccal surfaces of the molars to measure the intermolar
distance.14
An overview of recent scientific literature
shows the limited emphasis and evidence available on the transverse growth of jaws. A significant number of people present with transverse
jaw discrepancies, demanding special attention
to this plane of space. Intraarch asymmetries are
found to be more severe in the transverse than
in the AP plane.15 Early diagnosis is critical for
the correction and treatment of such discrepancies. The multifactorial etiology behind the development of transverse discrepancies makes
identifying and eliminating the etiologic factor
difficult. The goal of the present article is to
provide an in-depth summary on transverse
growth changes of the craniofacial and dentoalveolar complex. In addition, the potential for
predictive growth changes at 6 years and 12 years
will be presented.
Methods
The research16 done at the University of Oklahoma presents information on longitudinal records of 25 males and 25 females between the
ages of 6 and 18 years. All subjects had Class I
occlusion with absence of crossbites and no history of orthodontic treatment. The current study
uses the same data to investigate the age at
which predictive potential of future growth is
the strongest. The information recorded as average size and annual increments of 9 transverse
dimensions (Fig. 1) identified relationships be-
102
Nanda, Snodell, and Bollu
Figure 1. Transverse measurements. 1: cranial width
(bieuryon width); 2: facial width (bizygomatic width);
3: nasal width (bialare width); 4: maxillary width; 5:
mandibular width (bigonial width); 6, 7: maxiallary
intermolar width (6-6 and 7-7); 8, 9: mandibular intermolar width (6-6 and 7-7). (Reprinted with permission from Snodell et al.10)
tween various facial measurements, indicated
growth patterns, and formulated predictive
equations. Transverse growth of all 9 measurements at 6, 12, and 18 years was compared.
Regression analysis was performed to assess the
predictive potential at 12 years, using 18 years as
the adult size.
Findings
In this section, craniofacial and dentoalveolar
transverse measurements between 6 and 18 years
will be summarized. The percentage growth
completions have been assessed with reference
to an adult size. The terminal age in this report
is 18 years, hence all references to adult size
mean 18 years. Small growth increments may
still be taking place in some measurements even
after age 18 years, and hence, it is important to
note that the projected adult sizes are the closest
possible approximations. Least square means for
all measurements at each age were calculated.
Cranial width is about 95% complete at age 6
years. Adult size is attained by 14 years in females
and 17 years in males. Cranial width was found
not to be statistically correlated with any skeletal
transverse measurement except facial width.
Facial width increases between 6 and 11 years
in females and 6-13 years in males at a rate of
1.5-2 mm per year, with a peak growth spurt at
14 years for females and 15 years for males.
Growth is complete at 17.5 years in females, but
it continues at the rate of 1.75 mm per year in
males even at 18 years. By 6 years, males reached
83% and females reached 86% of adult facial
width. Facial width showed positive correlation
with all skeletal transverse measurements in females; however, this correlation was not observed in males.
The least square means for nasal width at 18
years ranged from 25.6 to 33.7 mm for females
and from 29.2 to 36.5 mm for males (Table 1).
The total increment was 5.8 mm for females and
7.5 mm for males, although both had about the
same nasal widths at 6 years. At 6 years, about
75% of nose width is complete in males and 80%
in females. The maximum increase in nasal
width is between 10 and 11 years in females. In
males, it was observed at 8-10 years and again at
15 years. Nasal width showed a positive correlation with facial width.
Bizygomatic width, a measure of maxillary
width, increases most from 2 to 6 years. Bizygomatic width is larger in males when compared
with females by 2.0 mm at 2 years, 3.4 mm at 10
years, and 6.2 mm at 18 years. Maxillary width on
an average increased 10.1 mm in males and 7.4
mm in females (Table 2). The curve for total
percent completion of growth of the maxilla
shows accelerated growth from 8 to 12 years and
a steady increase until full width is achieved at 15
and 16 years in males and females, respectively.
The incremental pattern suggests accelerated
growth in width with development of maxillary
molars. At 12 years, maxillary width is complete
by 98% in females and 95% in males.
The least square means of mandibular width
from 6 to 18 years are shown in Table 3. The
mandibular width increased by 15.8 mm in females and 20.9 mm in males from age 6 to 18
years. The growth increments during 8-11 years
contributed 6.3 mm in females and 7.3 mm in
males. At 18 years, mandibular width continued
to show a small increase in males and females.
Maxillary intermolar width from 6 to 18 years
is shown in Table 4. The intermolar width at the
maxillary first molars increased by 2.0 mm in
females and 6.3 mm in males. The average width
at 18 years was 55.7 mm for females and 59.5 for
103
Transverse Growth of Maxilla and Mandible
Table 1. LSMean, SD, Min, and Max Values for Nasal Width in Millimeters for Males and Females Aged 6-18
Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
6
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
22
17
19
20
21
22
21
21
19
22
19
21
21
23
20
22
16
21
18
17
19
14
20
15
11
9
22.93
22.88
23.48
23.17
24.56
24.09
24.70
24.58
26.12
24.94
26.49
26.14
27.39
26.55
27.84
27.14
27.81
27.70
28.98
28.12
29.10
28.32
29.88
28.76
30.48
28.64
1.92
1.66
2.03
2.10
1.87
2.16
2.06
2.42
2.11
2.55
1.77
2.23
2.54
2.45
2.44
2.60
2.64
2.15
2.66
2.50
2.42
3.13
2.40
3.12
2.07
2.49
18.21
19.87
20.77
19.13
20.13
20.16
21.05
21.83
23.30
20.09
23.98
20.09
23.02
21.38
23.54
21.10
22.93
25.08
25.48
25.31
24.57
22.90
24.81
21.72
29.25
25.56
26.98
26.42
27.50
26.78
27.86
27.97
28.88
29.60
29.72
29.87
29.72
29.87
32.20
30.58
32.70
32.40
31.93
33.06
33.88
34.08
35.07
33.25
35.26
34.62
36.55
33.68
7
8
9
10
11
12
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
males. Interestingly, by 6 years of age, the maximum intermolar width achieved was 96% in
females and 88% in males. Maxillary intermolar
width at second molars showed an increase of
1.4 mm in females, whereas the males showed an
increase of 3.7 mm (Table 5).
The least square means of mandibular intermolar width are shown in Table 6. Transverse
growth change in this area was found to be little,
with a slight decrease until 11 years. The mandibular intermolar width at the second molars
(Table 7) decreased by 2.1 mm in females and
1.2 mm in males from age 12 to 18 years.
Table 8 presents the percentage completion
of each transverse craniofacial dimension at 6
years and at age at which 100% growth was
found to be complete. All dental measurements
were found to be highly correlated with each
other. Although most skeletal and dental transverse growth was almost complete before 18
years in females, mandibular width continued to
grow beyond 18 years. Mandibular intermolar
width at first and second molars, however, was
fully complete before 15 years in both males and
females. In males, except for facial width, most
skeletal and dentoalveolar measurements continued to increase beyond 18 years.
Predictions of Dental Arch Widths
Different approaches have been proposed to
predict the maxillary and mandibular arch
widths. Some well-recognized indices to predict
maxillary arch width include analyses by Pont,17
Howe et al,18 and Schwarz and Gratzinger.19
Mandibular arch width measurements have
been done in several different ways. Bonwill20
used the sum of 6 anterior teeth to predict mandibular arch width. Many earlier studies developed indices based on limited variables leading
to potential biases. Recent investigations by Nimkarn et al21 criticized the inaccuracies inherent
in several indices. The advantages of using regression analyses over indices in making growth
predictions of dental arches were first used by
Snodell et al10 (Figs. 2–19) and more recently by
Alvaran et al.22
Our research at University of Oklahoma indicates that growth at 6, 12, and 18 years showed
reliable and discernible patterns. Our investiga-
104
Nanda, Snodell, and Bollu
Table 2. LSMean, SD, Min, and Max Values for Maxillary Width in Millimeters for Males and Females Aged
6-18 Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
6
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
22
17
21
21
21
24
22
23
19
22
21
22
21
23
23
22
18
20
15
17
20
14
20
15
11
9
56.17
54.44
57.67
55.52
58.63
56.71
60.04
58.06
61.37
58.86
62.81
59.73
63.03
60.26
63.51
60.83
64.16
61.42
65.81
62.09
66.02
61.96
66.17
61.88
66.24
61.80
2.34
1.86
2.23
2.10
2.16
2.23
2.53
2.39
2.88
2.34
2.82
2.68
2.99
2.79
2.99
2.57
3.20
3.19
3.17
3.06
3.56
2.49
3.34
2.54
3.12
2.97
51.13
51.28
53.66
51.28
54.76
51.34
55.83
54.60
57.18
55.25
58.17
55.03
59.69
56.73
59.69
56.73
59.20
56.65
62.41
57.65
60.49
57.42
60.73
56.32
61.08
58.67
60.19
59.00
61.64
60.04
62.55
62.45
64.56
63.40
66.42
64.07
68.73
65.30
68.90
66.68
68.90
66.68
68.69
68.40
72.07
68.32
72.22
64.84
71.51
64.86
70.80
66.88
7
8
9
10
11
12
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
tion highlights the correlation between strength
of predictability and percentage growth-related
changes. Cranial width increased only by 4%-6%
between 6 and 18 years, indicating that most of
the transverse cranial width is completed by this
age, and that growth at 6 years could serve as a
valuable reference point when predicting transverse growth. However, predictability of growth
completion based on growth at 12 years was
more significant than that at 6 years (Table 9).
At 12 years, maxillary width is complete by 98%
in females and 95% in males.
Factors Influencing Transverse Growth
Genetics
“It is estimated that about two-thirds of the
25000 human genes are involved in the complex
process of craniofacial development.”2 External
or internal influences on this process could alter
the pattern of craniofacial growth and development. Developmental disturbances, such as
clefts in the lip and palate, may adversely influence growth in the transverse dimension.
Age
Age is an important determinant of skeletal as
well as dental maturation. In this context, it is
important to emphasize that chronologic age
and dental age do not match quite often. Although most transverse craniofacial growth is
complete by age 18 years, our research shows
that dental transverse measurements (maxillary
and mandibular intermolar widths) reach adult
size by age 6 years. The timing of the adolescent
growth spurt largely influences treatment decisions, and hence, it is important to seek appropriate diagnostic measures, such as hand-wrist
x-rays or cervical vertebrae, to identify peak of
the adolescent growth spurt. Transverse growth
of the maxilla, for instance, shows a distinct
adolescent peak at 14-15 years.23 The findings
from our research substantiate further the role
of age in understanding transverse growth.
Gender
Transverse dimensional differences between
boys and girls were most notable at age 16 years
105
Transverse Growth of Maxilla and Mandible
Table 3. LSMean, SD, Min, and Max Values for Mandibular Width in Millimeters for Males and Females
Aged 6-18 Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
6
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
23
17
22
23
21
24
22
23
19
21
22
23
21
24
23
22
18
23
18
17
20
14
20
14
11
9
78.43
76.33
80.99
78.56
83.17
80.72
85.15
82.67
86.65
84.16
88.43
85.51
89.66
87.03
91.20
88.29
92.81
90.21
95.71
90.94
97.24
91.80
98.47
91.86
99.36
92.17
4.42
2.77
4.92
3.40
5.07
3.22
4.85
3.68
5.61
3.21
5.11
3.84
5.27
3.89
5.25
4.20
5.25
4.06
6.36
3.87
6.20
5.06
6.46
4.90
5.17
3.96
72.48
72.37
75.43
71.57
72.94
73.36
77.82
74.42
78.83
78.07
79.97
77.02
80.73
77.72
82.60
79.10
83.74
80.75
85.95
81.55
86.31
83.63
88.45
83.30
89.70
84.89
90.15
81.14
93.40
83.17
95.08
85.57
95.98
88.97
97.76
90.47
99.94
90.00
100.40
92.82
103.30
93.99
104.53
96.62
108.55
96.62
110.53
98.58
112.46
97.57
108.92
96.39
7
8
9
10
11
12
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
in the maxilla and at age 17-18 years in the
mandible.10,11 Gender differences in arch widths
were reported at later ages by some authors24
and at younger ages by others.13,22 Boys have
larger arch widths than girls, which become
more prominent in adolescence. Girls show
more arch dimensional changes than boys. Gender differences in intermolar widths were more
pronounced than interpremolar or intercanine
widths with boys having larger intermolar
widths.22 The difference in facial widths between
males and females is more prominent at the end
of adolescence, with males having a facial width
of ⫹3.4 mm at 10 years and ⫹6.2 mm at 18
years.25 The adolescent growth spurt was found
to be 1-3 years later in boys when compared with
girls.23 Transverse growth changes were found to
reach near completion by about 15 years of age
in females and about 17 years of age in males.
Race and Ethnicity
Race is one of the biggest challenges in developing or using normative data. The transverse skeletal and dentoalveolar measurements, mean
growth rates, and maximum extent vary signifi-
cantly between races. Chinese adults present
with significantly larger facial widths when compared with the American white population.26
Another parallel phenomenon is the issue of
secular changes. Cranial size and morphology
have experienced a notable change over the past
century. Although mandibular body width and
bigonial breadth show significant decrease, the
mandibular body length has increased. These
secular changes were more pronounced in
whites than blacks.27
Growth Patterns
Growth of the craniofacial region occurs around
an axis of rotation. There appears to be a definite correlation between maxillary and mandibular transverse dimensional changes.28 The extent of transverse growth has been found to have
a relation to the morphogenetic facial pattern.
Vertical growers with a high mandibular plane
angle have been hypothesized to have lesser
transverse growth, and thereby lesser gain in
intermolar width. Wagner and Chung8 studied
this relation in a final sample of 81 patients
extracted from the Bolton and Burlington stud-
106
Nanda, Snodell, and Bollu
Table 4. LSMean, SD, Min, and Max Values for Maxillary Intermolar Width (6-6) in Millimeters for Males
and Females Aged 6-18 Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
6
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
9
10
12
15
18
24
22
23
19
22
21
23
21
22
21
22
17
22
17
16
21
14
18
15
10
9
53.18
53.67
55.40
53.87
55.25
54.55
56.95
54.55
57.46
54.88
58.00
55.41
58.22
55.63
58.25
55.72
58.38
55.55
58.65
55.86
58.98
55.98
59.41
56.17
59.46
55.67
2.66
2.58
2.43
2.25
2.80
2.22
2.66
2.42
2.86
1.90
2.75
2.17
2.69
2.19
2.91
2.03
3.02
2.07
3.27
2.58
3.25
2.77
3.54
2.70
2.71
1.51
50.98
49.13
51.14
49.07
51.22
48.60
52.60
48.70
53.85
50.85
54.04
49.63
57.23
49.77
53.98
49.53
53.85
48.93
52.38
48.95
53.98
48.01
53.35
53.54
54.26
54.60
58.45
56.79
59.28
57.00
60.72
57.47
61.39
58.20
61.67
58.43
62.17
58.62
64.95
59.95
62.83
58.27
63.36
58.29
63.40
60.25
64.11
59.53
65.05
64.47
63.39
59.29
7
8
9
10
11
12
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
ies, including low, average, and high mandibular
plane angles. Intermolar width increased gradually from 6 to 14 years and plateaued by age 14
in high-angle patients. Growth continued, although at a slower rate in patients with low and
average mandibular plane angles. This study
confirms that the vertical growth pattern exhibited by high-angle patients has a correlation to
lesser gain in intermolar widths. Chen et al29
analyzed 3-dimensional relationships between
maxilla and mandible in relation to the mandibular plane angle in a Japanese sample of 56
subjects between 8 and 14 years. They found that
the ratio of maxillary and mandibular width ([JJ/Ag-Ag] Jugale-Jugale and Antegonion–Antegonion) decreased and reported a higher
change in the low-angle group. Greater width
increases were noticed in the mandible when
Table 5. LSMean, SD, Min, and Max Values for Maxillary Intermolar Width (7-7) in Millimeters for Males
and Females Aged 12-18 Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
12
M
F
M
F
M
F
M
F
M
F
M
F
M
F
9
11
12
14
14
18
16
17
21
14
20
15
11
9
61.27
59.32
61.94
60.26
62.51
60.53
63.20
60.86
64.05
60.73
64.32
60.87
65.01
60.72
3.54
3.09
3.24
2.88
2.77
3.04
3.47
2.79
3.53
2.87
3.43
2.77
3.10
2.07
57.89
54.78
57.94
54.20
57.16
54.40
57.96
54.16
58.43
52.93
59.83
53.54
60.53
58.58
67.03
64.34
67.13
64.18
66.22
65.97
68.90
65.84
69.78
64.52
69.16
64.47
70.12
64.00
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
107
Transverse Growth of Maxilla and Mandible
Table 6. LSMean, SD, Min, and Max Values for Mandibular Intermolar Width in Millimeters for Males and
Females Aged 6-18 Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
6
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
M
F
10
13
18
20
20
23
22
23
19
22
21
22
20
24
22
22
18
22
17
17
21
14
20
15
10
9
56.00
54.10
55.70
54.22
55.90
53.90
55.74
54.30
55.68
54.19
55.92
54.17
56.33
54.32
55.93
54.03
55.86
54.23
55.94
54.07
56.39
53.84
56.30
54.05
56.12
53.72
2.96
2.17
2.83
2.08
2.89
2.04
2.35
1.97
2.39
1.67
2.23
2.07
2.39
2.33
2.45
2.34
2.69
2.61
2.97
2.74
2.61
2.91
3.18
3.21
2.17
1.55
49.66
49.45
50.92
50.33
52.11
48.00
51.55
48.38
52.61
51.14
52.30
48.30
52.38
47.56
52.02
47.17
50.67
45.56
49.84
45.93
51.17
46.45
51.19
45.91
51.57
52.28
62.38
59.84
63.03
60.18
63.77
57.37
60.54
57.37
61.90
57.21
61.22
57.57
61.56
58.22
60.75
57.25
61.92
57.66
61.89
57.84
60.88
57.12
62.20
57.43
58.39
56.98
7
8
9
10
11
12
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
compared with the maxilla, confirming the findings of previous studies.11
Habits
Habits, such as mouth breathing, have a profound effect on the extent of transverse
growth of the jaws. An absolute correlation
exists between respiratory pattern and craniofacial growth. Although muscular imbalance
has been regarded as one of the main contributors,30 the true mechanism responsible for
arch constriction is beyond the scope of this
article. Paul and Nanda31 in their experimental study comparing mouth breathers with nasal breathers found that the maxillary arch
width was highly constricted, but the arch
length was much longer in the mouth breathers. Mouth breathers tend to have a poor lip
Table 7. LSMean, SD, Min, and Max Values for Mandibular Intermolar Width (7-7) in Millimeters for Males
and Females Aged 12-18 Years
Age (Years)
Gender
Subjects
LSMean
SD
Min
Max
12
M
F
M
F
M
F
M
F
M
F
M
F
M
F
12
16
21
21
17
23
17
17
20
14
19
15
10
9
64.55
62.43
63.72
61.17
63.03
61.26
63.21
60.65
63.46
60.39
63.72
60.73
63.36
60.37
3.24
2.88
2.73
2.48
2.43
2.71
3.39
2.69
3.06
2.77
3.77
3.29
2.71
1.36
58.13
56.33
58.25
55.47
57.00
55.06
56.52
54.09
57.74
54.17
58.29
52.50
57.20
52.28
68.84
65.65
67.65
64.74
66.69
65.34
71.07
63.89
70.89
64.14
72.59
64.63
66.49
63.98
13
14
15
16
17
18
LSMean, least squares mean; SD, standard deviation; Min, minimum; Max, maximum; F, females; M, males.
108
Nanda, Snodell, and Bollu
Table 8. Percentage Completion of Width at 6
Years, with 100% Being Considered at 18 Years
Transverse
Measurement
Facial width
Nasal width
Maxilla width
Mandibular width
Maxillary intermolar
width (6-6)
Maxillary intermolar
width (7-7)
Mandibular
intermolar width
(6-6)
Mandibular
intermolar width
(7-7)
Extent of Growth
Completed at 6
Years (%)
100% Complete
at Age (Years)
Female
Male
Female
Male
83
75
85
78
89
86
80
88
88
89
18
18
16
18
17
17
17
15
16
17
94
94
14
18
100
101
—
—
102
103
—
—
tonicity leading to increased growth in the
sagittal plane. Hence, these patients often
present with an increased overjet. The limited
arch width was more noticeable in the maxilla,
whereas in the mandible, perhaps the tongue
Figure 3. Regression line and 95% confidence interval
for facial width in males. Values at ages 6 or 7 and 18 or
19 years were used to calculate the regression line.
prevents the collapse of the arch form, thereby
preserving the arch width.
Muscles
Figure 2. Regression line and 95% confidence interval
for cranial width in females. Values at ages 6 or 7 and 18
or 19 years were used to calculate the regression line.
The role of muscles on facial dimensions and
proportions has been studied extensively. The
review article by Kiliardis32 explores this topic
and identifies elevator muscles of the mandible
to exert an influence on the transverse and vertical facial dimensions. The biomechanics involved in this phenomenon are complex; heavy
muscle forces because of masticatory muscle hyper function, perhaps increase the sutural
growth and bone apposition, ultimately resulting in an increased transverse growth of the
maxilla and broader bone bases for the dental
arches. A definite correlation seems to exist between cross-sectional areas of temporalis and
masseter muscles with facial width.33 In the
lower jaw, the tongue being a very strong muscle
influences the arch width. Lateral growth of the
lower jaw was significantly reduced in glossectomized animals, leading to highly constricted intercanine and intermolar widths.34
Transverse Growth of Maxilla and Mandible
109
however, may be due to a deficiency in the initial
size and not because of growth differences in
later stages. Bishara et al38 confirmed that no
differences were observed in the growth changes
between normal and Class II subjects. Class II
tendency is observed early on in the primary
dentition and tends to persist into the mixed
dentition.39,40 If this problem is not corrected in
the initial stages, the discrepancy will not selfcorrect and the same discrepancy continues into
adulthood.
Orthodontic Intervention
Beside changes observed in growth, increases in
transverse arch dimensions are often observed
during orthodontic treatment.41 A definite pattern seems to exist between molar uprighting
and increase in transverse maxillary basal bone
width.9 Prolonged use of orthodontic appliances
could actually hinder growth.22
Discussion
Figure 4. Regression line and 95% confidence interval for facial width in females. Values at ages 6 or 7
and 18 or 19 years were used to calculate the regression line.
Early growth studies were based on direct anthropometric measurements of human faces or
Skeletal Differential
The mandibular posterior extent acts as a limiting factor to the width of the maxillary intermolar width. The review article by Vanarsdall35 provides great insights into this concept of skeletal
differential and highlights the importance of
early diagnosis of transverse discrepancy. The
difference in intermolar widths of the maxilla
and mandible is referred to as posterior transverse interarch discrepancy. The clinical implication is that mandibular posterior teeth affect
the maximum extent of maxillary expansion
that a clinician can expect to achieve.
Malocclusions
Transverse development of jaws has been found
to be influenced by malocclusions, such as openbite36 or Class II division 1.12 Maxillary skeletal
base widths are smallest in the Class II division 1
category, and the difference in maxillary and
mandibular intermolar widths remained the
same from 7 to 15 years of age.37 The transverse
deficiency seen in Class II malocclusion patients,
Figure 5. Regression line and 95% confidence interval
for nasal width in males. Values at ages 6 or 7 and 18 or
19 years were used to calculate the regression line.
110
Nanda, Snodell, and Bollu
Figure 6. Regression line and 95% confidence interval for nasal width in females. Values at ages 6 or 7 and
18 or 19 years were used to calculate the regression
line.
dried skulls (craniometry).42 Variations in softtissue thickness limited the accuracy of this approach. Another major limitation of the anthropometry and craniometry is the inability to
perform longitudinal studies.2 As radiography
evolved, numerous growth studies have been
done using lateral cephalograms as the primary
imaging resource. Implants’ studies alongside
cephalometry have since been used by several
other researchers to monitor growth changes.
Although lateral cephalometric radiographs
can provide a good view to assess vertical and
sagittal growth, the frontal view (A-P) offers a
better perspective in measuring transverse and
vertical growth changes of the face. One major
concern with PA views, however, has been the
potential for magnification errors due to varying
distances between the objects and film. The
weaknesses inherent in PA views were pointed
out by Woods43 several decades ago. For instance, the intercanine width was argued to be
less magnified than the bigonial width because
the gonial angles are farther away from the film
when compared with the upper canines. Lack of
access to better imaging modalities has limited
researchers to continue using PA views for
growth studies. However, several geometrical approaches have since been developed to correct
the magnification errors,44 thereby aiding in better interpretation of the data from PA views.
Beside superimpositions and image magnifications inherent in 2-dimensional images, any
attempts to extrapolate a multidimensional concept with 2-dimensional views are debatable.
With the increasing access to cone-beam computed tomography technology, more studies
may be expected to use the benefits that this
advanced imaging can offer. More importantly,
the use of multiple views to evaluate growth
changes is warranted.
Chronologic age serves as a simple milestone
in evaluating growth patterns and making predictions of future growth. However, several studies have investigated the accuracy of using
chronologic age as an indicator in comparison
with biological age.45,46 In an attempt to provide
a general guideline to the clinician when evaluating growth patterns, we have used chronologic
age as a marker to identify key growth mile-
Figure 7. Regression line and 95% confidence interval
for maxillary width in males. Values at ages 6 or 7 and 18 or
19 years were used to calculate the regression line.
Transverse Growth of Maxilla and Mandible
Figure 8. Regression line and 95% confidence interval for mandibular width in males. Values at ages 6 or
7 and 18 or 19 years were used to calculate the regression line.
stones, using observations from previous studies.
It is imperative that the readers take into account individual variations when making inferences on growth patterns and predictions.
A caveat to readers is the potential issue of
secular changes. The longitudinal records used
in the current research article were taken from
archives of the Child Research Council, Denver,
CO. The records were collected from the early
1930s to the mid-1960s of the 20th century. It is
possible that the growth behavior and size of the
current population may be earlier maturing and
larger.
A major limitation observed in the majority of
growth studies attempting to predict growth extent is the use of a certain age as near completion. Although transverse growth may be complete by late adolescence, growth is found to
continue in other dimensions. Relative growth
in other dimensions could erroneously hamper
true calculations when one attempts to identify
the complete extent of growth in 1 dimension.
Several studies showed that the skeletal and
dentoalveolar growth increments are different
111
for the maxilla and the mandible. The mandibular width showed greater increase than the
maxillary width.11,47,48 In contrast, the intermolar width showed greater increases in the maxilla
than the mandible.10,14,24 This distinction is of
great clinical significance in determining the
timing and extent of expansion.
Overdependence on the linear dentoalveolar
dimensional changes carries the risk of overlooking underlying skeletal discrepancies. To establish sound treatment objectives, it is important
to recognize the correlation between dentoalveolar and supporting skeletal structures. This correlation in transverse growth between craniofacial skeletal and dentoalveolar structures has
been highlighted several decades ago.49
A review of some recent literature on transverse growth follows. Using Bjork-type implants,
Korn and Baumrind50 reported longitudinal
data on transverse dimensions of the maxilla
and mandible on a sample of 31 subjects between ages 8.5 and 15.5 years. Lateral and frontal radiographs were taken annually. Transverse
widening was observed in the posterior-most
Figure 9. Regression line and 95% confidence interval for mandibular width in females. Values at ages 6
or 7 and 18 or 19 years were used to calculate the
regression line.
112
Nanda, Snodell, and Bollu
Figure 10. Regression line and 95% confidence interval for facial width in males. Values at ages 11 or 12
and 18 or 19 years were used to calculate the regression line.
area of the palate at a mean annual rate of 0.43
mm.
With the goal of establishing normative data,
Athanasiou et al14 performed a cross-sectional
investigation on a sample of 588 Australian children between 6 and 15 years of age. Findings
from this study showed a gradual increase in the
transverse skeletal dimensions during the study
period. The maxillary and mandibular intermolar widths, however, remained relatively constant
between 9 and 12 years. The ratio between the
maxillary intermolar width and interorbital
width decreased between 8 and 13 years but
increased during 14 and 15 years.
Cortella et al11 in an attempt to generate new
norms for PA cephalometric analyses used the
Bolton-Brush study sample to examine the transverse relationship between the maxilla and mandible during growth. This study adjusted the
norms from Bolton-Brush study in accordance
with radiographic enlargement. Statistically significant increases in annual rates of growth were
observed at 7 and 10 years. This study focused on
the differences in growth patterns between boys
and girls. The authors found that the growth
patterns are similar in both genders until 11
years, and some differences are observed beyond
12 years.
The implant study by Gandini and Buschang28
was performed on a sample of 25 subjects between
12 and 18 years of age. Using Bjork’s technique,51
implants were placed on the maxillary and mandibular corpora. In the maxilla, implants were
placed on either side of the anterior nasal spine
for anterior measurement and on the zygomatic
process bilaterally for the posterior measurements.
In the mandible, implants were placed inferior to
the first molar bilaterally for posterior measurement and in the midsymphyseal region anteriorly.
Lateral and frontal radiographs were taken periodically during the study to capture the movement
of the implants along with skeletal growth-related
dimensional changes. The anterior maxillary implants showed a decrease of 0.2 mm, whereas posteriorly, the distance increased by 0.6 mm in the
mandible and 0.8 mm in the maxilla. The maxillary growth was found to be 0.4 mm per year,
whereas the mandibular growth rate was at 0.1 mm
per year.
Figure 11. Regression line and 95% confidence interval
for facial width in females. Values at ages 11 or 12 and 18
or 19 years were used to calculate the regression line.
Transverse Growth of Maxilla and Mandible
113
was achieved at about 4-5 years later in the second molar region. Accelerated increases in the
canine arch width were noted between 5 and 8
years. Maxillary arch width increase was found to
be larger than that of the mandibular arch.
Yavuz et al47 investigated longitudinal transverse and vertical growth changes between 10
and 14 years in a Turkish sample of 45 subjects.
The largest incremental width changes were observed in mandibular intermolar width for the
study period. Gender differences were more notable in the transverse skeletal measurements
when compared with the vertical changes. Mandibular widths measured at 10 years were 93.2
mm in males and 92.3 mm in females.
Hesby et al9 investigated the growth-related
molar movements and torque changes. They reported that maxillary and mandibular intermolar crown torque changes are accompanied by
concurrent increases in the corresponding intermolar widths. Maxillary skeletal and dentoalveolar transverse measurements were found to
reach adult extents by 16.5 years. Greatest width
Figure 12. Regression line and 95% confidence interval for nasal width in males. Values at ages 11 or 12
and 18 or 19 years were used to calculate the regression line.
The longitudinal PA cephalometric study by
Lux et al13 used radiographs and dental models
of 18 normal occlusion subjects with the aim of
identifying craniofacial and dental transverse
growth patterns. These changes were observed
at 2-year intervals from ages 7 to 15 years. In
both males and females, statistically significant
growth changes were observed in the intermolar
widths between 7 and 11 years. The authors
found that except mandibular intermolar width,
all skeletal and dental transverse dimensions increased from 7 to 15 years. Gender differences
were found to be most pronounced at 15 years.
Stephens et al52 evaluated arch dimensional
changes using radiographs of 21 Caucasian children between 2 and 20 years of age. An interesting finding from this study was that the maximum arch width was achieved not soon after
tooth eruption but 2-3 years later, in general.
The arch width gain was delayed further in the
molar region. The maximum arch width was
noted about 6-8 years, following eruption in the
permanent first molar region, whereas the same
Figure 13. Regression line and 95% confidence interval for nasal width in females. Values at ages 11 or
12 and 18 or 19 years were used to calculate the
regression line.
114
Nanda, Snodell, and Bollu
Figure 14. Regression line and 95% confidence interval for mandibular width in males. Values at ages 11
or 12 and 18 or 19 were used to calculate the regression line.
changes were observed at the jugale points and
the smallest in the midalveolar point of the mandible. The authors indicated that because the
posterior teeth become upright and expand simultaneously by 3 mm in the maxilla and 2 mm
in the mandible, spontaneous mandibular molar
uprighting can be expected after maxillary expansion.
Chvatal et al53 developed the multilevel statistical models for longitudinal craniofacial growth
prediction. Longitudinal cephalograms taken
on subjects from 6 to 10 years were used to
predict craniofacial growth changes from 10 to
15 years. The authors concluded that longitudinal growth curves based on multilevel procedures can accurately reflect on the population
growth curves. They confirmed that 5-year predictions using these models are highly accurate
and that more longitudinal data do not increase
prediction accuracy. Correlations between predicted and actual measurements ranged between 0.81 and 0.96. The study also verified
external validity of the sample using predictions
with multilevel models.
Alvaran et al22 developed multiple regression
models for predicting arch widths, using anthropometric measurements, including body size, facial breath, and height along with tooth sizes. In
this study, a sample size of 473 Colombian mestizo children was grouped into primary, early
mixed, late mixed, and permanent dentitions.
The analysis of variance test showed nonsignificant interactions with age, gender and occlusion. Using calipers, interpremolar and intermolar widths were measured in each group.
Multiple regression analyses were used to delineate the influences of each independent variable. Beta coefficients were used to predict arch
widths. Bigonial width was found to be the most
influential predictor of interpremolar and intermolar arch widths. The sum of the incisor mesiodistal widths proved to be the best predictor of
maxillary and mandibular intercanine widths. In
essence, a direct correlation was observed between arch widths, incisors, and bigonial distance. For instance, individuals with large incisors and wide bigonial widths can be predicted
to have wide dental arches. Comparing their
Figure 15. Regression line and 95% confidence interval for mandibular width in females. Values at ages
11 or 12 and 18 or 19 years were used to calculate the
regression line.
Transverse Growth of Maxilla and Mandible
Figure 16. Regression line and 95% confidence interval for maxillary width in males. Values at ages 11
or 12 and 18 or 19 years were used to calculate the
regression line.
115
width was an exception that was only 75%
complete by 6 years of age.
2. Statistically significant differences were found
between male and female measurements: at
age 6 years, between mean width of cranium,
face, and maxilla; at age 12 years, the differences were between cranial width, maxillary
width, and maxillary-mandibular intermolar(6-6) widths; at age 18 years, all variables
were different, except the nasal width and
mandibular intermolar (6-6) width.
3. In females, the cranial and facial width spurts
were at 8 years and nasal width was at 11
years. In males, the cranial width growth
spurt was at 12 and 14 years, facial width was
at 7 and 15 years, and nasal width spurt was at
10 and 17 years. No growth spurts in the
maxillary and mandibular widths for females
were recorded.
4. Transverse growth of the face is near complete by age 18 years, although, nasal width
still shows growth increments. As growth in
the width of the maxilla and the nose largely
occurs between 7 and 11 years of age, patients
results with Pont’s index, Schwarz analysis, and
the McNamara rule of thumb, the authors of this
study concluded that multiple regressions serve
as better tools in predicting arch widths.
Summary
Longitudinal records of 50 (25 male, 25 female)
AP cephalometric radiographs were selected
from the archives of Child Research Council,
Denver, CO. From serial cephalometric measurements, growth was evaluated from the group
means. Annual increments for each variable and
periods of growth acceleration were identified.
Growth spurts were defined as the rate of mean
annual growth increment exceeding that in the
preceding annual interval by at least 0.75 mm.
The following observations may be considered:
1. The transverse growth was completed for the
majority of measurements for both males and
females by age 18 years. Each of the measurements was complete by over 80% by age 6
years relative to the size at 18 years. Nasal
Figure 17. Regression line and 95% confidence interval for maxillary width in females. Values at ages 11
or 12 and 18 or 19 years were used to calculate the
regression line.
116
Nanda, Snodell, and Bollu
Table 9. Predictability for Each Variable at Ages 6
Years and 12 Years
Transverse
Measurement
Cranial width
Facial width
Nasal width
Maxillary width
Mandibular width
Maxillary intermolar
width (6-6)
Mandibular
intermolar width
(6-6)
Figure 18. Percentage change for each variable in
males and females from age 6 to 12 years expressed as
a proportion of the value at age 6 years. (Color version of figure is available online.)
requiring orthopedic expansion of the maxilla may be treated with advantage during this
period.
5. Linear regression analysis at 6 years revealed
strong predictability (R2 ⱖ 0.60) in both genders for cranial width, facial width, and mandibular width. The predictability was only
moderate (R2 ⬎ 0.40 ⬍ 0.60) for nasal width
and maxillary width. However, at age 12
years, the predictability for all craniofacial
and dentoalveolar transverse measurements
was strong.
Our data show a strong predictive potential at
12 years of age when measuring transverse
growth in the craniofacial and dentoalveolar
structures. Considering the clinical implications
of growth predictions in effective orthodontic treat-
Figure 19. Percentage change for each variable in
males and females from age 6 to 18 years expressed as
a proportion of the value at age 6 years. (Color version of figure is available online.)
Male
Female
6 Years 12 Years 6 Years 12 Years
XXX
XXX
XX
XX
XXX
—
XXX
XXX
XXX
XXX
XXX
XXX
XXX
XXX
X
XXX
XXX
—
—
XXX
—
XXX
XXX
XX
XXX
XXX
XXX
X
XXX, strong; XX, moderate; X, weak.
ment planning, further research is warranted in this
area.
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