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Variability of the craniofacial skeleton
Variability of the craniofacial skeleton II. Comparison between two age groujx Heli
Vinkka,
LOdont.,
and
Kalevi
Koski,
D.Odont.*
Pidand
lTurku,
T
he variability of the craniofacial skeleton was recently analyzed in a sample of child skulls.” The analytical method was constructed to focus on some presumabl>- meaningful anatomic relationships. The sample was selected not only according to age but also on the basis of occlusal normality. At the time of collection of the infant skull material, a very small samplr of adult skulls was also available. I’rcliminary observations from the two samples indicated that the application of the method to a coniparat,ive study on different age groups might bc rewarding, and the present stutly was therefore undertaken. Muterial
and
methods
The material consisted of two samples of lateral s-ray cephalograms, forty in each sample. The first sample was from a collection of ccphalograms of Finnish schoolgirls, 6 to 8 years of age, radiographed without selection.“’ The second sample was drawn from a collection of radiograms of Finnish fcmalr dental ‘~1 to 28 scars, also taken without selection.” A st,andardized studrnts, aged __ tcchniyuc dcscribctl it) the original publications was used. The method of analysis was essentially the same as in the previous study,” but two new lines were added to the original twelve lines’” (Fig. 1). The mutual angular relationship of thcsc fourtccti lines were studied. Since it was obvious that the definition of some of the lines would be tiiffieult in some instances. both of us c~hcckctl through tht> whole material togct’hcr, determining how the lines should bc visnalizcd. Thcreaftcr, the first author alone measured the material. [Ysing tracing sticcts pln~ecl on the films, the lines w’cro drawn to the anatomic lengths of the structures to b(> rcpresentetl ant1 were not estcndcd to uoss each other. Tn casts of double images in the films, the lines wcr”c drawn to rcprescnt the geometric means of the double images. A large, speciall) made protractor, equipped with a movable indicator ilrtn, was used to measure the angles formed by the line ORB with all the other lines, tllatI is, a set of thirteen “Chairman, University
34
Department of Turku.
of
Pcdodontics
and
Orthodontics,
Institute
of
Dentistry,
Variability
Fig.
1. The
lines
used
in the
analysis:
1, Tangent
to the
of craniofacial
posterior
slope
of the
skeleton
orbital
35
roof,
ORB; 2, tangent to the spheno-ethmoidal line, SPHEN; 3, line depicting the infraorbital canal, INFRA; 4, tangent to the nasal floor posterior to the incisal canal, PAL; 5, occlusal line, through the most anterior and posterior contact points between the upper and lower deciduous molars/premolars and first permanent molars, OCCL; 6, line depicting the anterior part of the mandibular canal under the occlusal line, AMC; 7, tangent to the mandibular base, MAND; 8, line depicting the posterior part of the mandibular canal, PMC; 9, tangent to the posterior border of the ramus, condylar process excluded, RAMUS; 10, tangent to the posterior border of the condylar process, COND; 11, tangent to the cerebral surface of the clivus, dorsum sellae excluded, CLIVUS; 12, tangent to the ventral surface of the pterygoid process, PTER; 13, tangent to the pharyngeal surface of the clivus, PHAR; 14, the foraminal line, opisthion-basion, FOR.
angles. The angular relationships between the rest of the lines were then calculated, thus obtaining figures for a total of ninety-one angles between the fourteen lines. The readings were taken to the nearest 0.5 degrees. The majority of the angles were measured or calculated as opening ventrally, and only in instances where this would have led to values greater than 180 degrees was the dorsally opening angle recorded. The statistical treatment of the recorded and calculated values included the computation of means and variances and the testing of their differences by using the t test resp. the F test.
The means and variances of the angles between the fourteen lines in both age groups are given in Tables I and II.
36
l’ixkka
Table
I.
Koski
and
Means
and /
variances ORB
of SPIIEN
angles
/ 11VFRA
"5.3
ORB
in
a
PAL
j
sample
of
forty
OCCL
/
AMC
child
x-ray
1 MANI)
4!).3
22.4
36.8
50.2
51.0
23.9
3.0
Il.5
L’5.:
26.9
12.4
24.9 0.9 27.x
1.7
13.4
14.2
SPHEiY
12.6i
ISFRA
32.00
26.40
PAI,
14.86
20.77
o(‘cr,
16.19 '5.62
20.99
26.39
13.21
AM (’
:16.65
35.05
30.33
27.84
15.22
3IAND
39.98 26.19
34.24
32.67
24.15
13.41
7.51
22.19
24.28
12.41
14.45
23.99
32.51
41.06
34.30
35.11
49.50
43.99
COND
31.31 33.20
38.59
29.60
31.13
34.93
39.51
PTER
48.71
53.85
32.89 36.30
36.17
31.16
48.02
45.54
CLIVUS
23.78
22.35
14.46
21.81
37.69
34.90
PHAR
34.86
21.2i 40.88
36.91
24.82
32.63
48.95
47.94
FOR
38.86
39.30
21.32
23.88
25.40
45.71
43.42
PM< RAMUS
The
underlined
Table
II.
means
Means
and
do not
differ
variances ORB
from
of
craniofacial
25.4
PAL
18.55 15.97
OCCL AMC MAND
INFRA
adult
angles
INFRA 45.5 20.1
5.84
SPHEN
14.4
the corresponding
SPHEN
ORB
The
craniofacial
18.03
1
in
means
a
28.6 0.8
(p <
17.47
0.01 j.
sample
of
forty
PAL
OCCL
)
AiW
24.1 1.3
30.0 4.6
42.5
47.8
17.0
22.4
2iz
15.5
-3.0 18.4
2.4 2E
12.4
17.8
5.9
adult
x-ray
] MAND
15.15
16.03 14.07
"1.79 17.18
13.26
40.77
39.86
37.03
45.86
21.22
34.50 25.48
27.06 19.04
36.44
16.57
6.20
PMC
33.99 27.27
24.08
23.94
18.44 15.27
20.40
26.74
18.20 18.03
26.87
RAMUS
43.31
32.72
COND
33.32
43.35
36.92
31.59
37.44
66.35
53.59
PTER
31.53
35.78
33.52
28.48 31.41
42.82
34.27
67.36
52.34
-
5.4
CLIVUS
36.92
37.10
46.17
27.71 25.06
PHAR
51.55
43.42
61.31
44.21
38.95
84.72
70.07
FOR
21.85
24.28
32.47
29.62
26.42
58.09
50.11
underlined
means
do
not
differ
from
the
corresponding
child
means
(p
<
0.01).
It appears that forty-seven of the ninety-one angles are not, on an average, statistically different in the two age groups, at the 0.01 risk level (t = 2.640). The smallest difference between means is 0.1 degree (ORB/SPHEN) ; the largest, 12.4 degrees (AMQ'PTER). The average figures indicate that several line patterns are similar in both age groups (Figs. 2 to 4). If the combination OCCL/AMC (these two lines have only this one mutual unchanging relationship) is omitted, the patterns can also be schematized in Chart 1. Several parallelisms, within 5 degrees from 0, were found between pairs of lines in the two age groups; four of these were the same in both groups. The angle INFRA/AMC had statistically different means in the two groups, but this
Variability
of waniofacia~l skeleton
37
cephalograms PMC
RAMUS
87.1 -
105.5
61.8
80.1
(
COWD -89.7 64.4
1
(
PTER
CLZPUS
PHAR
FOE 15.0
91.8
140.0
5.8
66.4
114.7
148.9
10.3
37.9
58.2
40.4
42.5
90.8
125.0
34.2
64.7 50.3
83.1 68.6
112.7
110.6
62.4
28.2
127.2
125.1
'i6.8
42.6
7.4 eix
143.1
124.7
140.5
138.4
89.8
56.0
143.9
125.5
141.3
139.2
5'6.8 92.9
18.4 28.52
35.2 36.0
2.6
4.7
91.0 127.1
-15.8
13.7
145.4
111.2
xi-
129.7
95.5
105.3
48.2
82.5
103.2
34.2 -
125.0
25.96
-
37.75
51.50
41.61
69.12
42.44
20.52
31.80
45.28
41.85
36.46
46.34
53.61
48.03
13.44
26.87
47.48
51.07
30.79
16.25
lo'i.9 89.6
159.2
cephalograms PMC
RAMUS
COND
PTER
85.1 59.6
108.2 82.8
91.8
96.5
140.2
66.4
71.1
39.6 61.0
62.8
46.3
51.0
114.7 94.7
149.1 129.0
84.1
112.3
107.6
55.0
78.2
118.3
113.5
-63.9 69.9
29.5 35.5
1ZZ
137.4
114.2
130.7
126.0
97.7
47.9
26.9
142.8
119.6
136.1
131.4
87.7
53.3
32.2
11.4
124.9 148.1
90.5 113.7
110.5
131.6 43.7
97.2 78.1
103.8
34.4 -
124.6
23.2 22.13
6.7 18.5 -
11.8 47 A
(
CLZVUS
37.35
40.73
23.82
33.60
32.95
38.83
38.28
54.56 39.56
42.51 30.75
46.53 62.76
29.78 58.44
21.75
48.75
37.96
34.26
1
PHAR 5.4
FOR 15.5 9.9 2G 8.6
87.3
99.1 159.0
49.32
angle fluctuates around 0, and the average parallelism still existed. This became clear when all the infraorbital and mandibular canals were drawn on the same paper, superimposing on the short, straight infraorbital canals (Fig. 5). A number of angles were within 5 degrees of 90 degrees, and again some of these were the same in both age groups. The variability of the angular relationships, expressed by the variances, can be inspected both within the total framework and by detail relationships. When the variances for each line are totalled, it can be seen that the order and range of values are different in the two age groups. Certain lines are involved in relationships of low variability in both age groups: PAL, OCCL, PMC, SPHEN, ORB, INFRA. The line COND has a large total variance in both age groups.
Fig. 2. Two patterns two age anatomic
groups, structures
of at
lines
whose
the 0.01 risk are illustrated.
mutual angular relationships level; instead of the actual
are lines,
in the not different the corresponding
ORB SPHEN .
. .
PAL .
.
.
INFRA .
.
.
. .
.
.-.-. .
MAND .
. -
pMC -
:
.
RAMUS
.
.
COND
.
.
.
.
PTER
.
CLIVUS
.
PHAR
PHAR
FOR CHART
1.
It may also be noticed how the CLIVUS, AMC, and PHAR lines become more variable when we move from the child sample to the adult one, whereas the lines RAMUS and PTER do just the opposite. Both ends of the mandibular canal, AMC and PMC, have their least variable relationship within the mandible with the MAND line and the most variable one with the line COND; the differences are statistically significant in both age groups (p < 0.05,F = 1.70). The AMC/RAMUS angle has a significantly larger variance in both age groups than the AMC/MAND angle (p < 0.01, F = 2.13). The RAMUS/ COND angle variance is nearly the largest of all variances involving the ramus in both age groups,
Variability
fig. 3. Two more patterns of lines whose mutual angular in the two age groups, at the 0.01 risk level, drawn to involved.
of craniofacial
relationships indicate the
skeleton
39
are not different anatomic structures
The variances related to the OCCL line are also interesting. The smallest variance in both age groups is found for the OCCL/PAL angle, but the occlusal plane seems to have relatively small variability to the mandibular body and canal (MAND resp. AMC, PMC) also, whereas its relationship with the condylar process (COND) is greatly variable. The OCCL/RAMUS angle has a large variance in the child group, but one of the smallest in the adult group. Discussion
From the technical point of view, mcasurcments on roentgen films should be taken directly from films, using clearly definable points and connecting lines and observing some other pertinent details.‘, 4, 23 In the present study the conceptual basis of the analysis has not permitted the ideal procedure. It has been shown elsewhere, however, that the methodologic error which represents the intraobserver error is within acceptable limits.2G The average parallelism between the infraorbital canal and the anterior part of the mandibular canal, found in the first study,12 was seen in the present two samples also. It can be mentioned here that the same relationship has been found also in young macaca monkeys. 27 The fact that the angular relationship between the infraorbital canal and the posterior part of the mandibular canal is different in the two age groups is readily explained by the size differcncc; the general form of the mandibular canal, stated to be a logarithmic spiral,2f seems remarkably constant (Fig. 5). The parallelism between the posterior part of the mandibular canal and the condyle (PMC/COND) , found here in children but not as clearly in
Fig. 4. The fifth level, illustrating
pattern of similar configurations the anatomic structures.
Fig. 5. The infraorbital and imposed on the infraorbital the right.
mandibular canals. The
in
both
canals drawn from child sample on the
age
the left
groups,
two and
at
the
samples the adult
0.01
risk
and supersample on
adults, is interesting since the spatial relationship between these two elements in human fetuses seems to be a close one.zi The present findings support the notion that the pterygoid process and the condylar process have a biologically meaningful perpendicular relationship to the lateral cranial base, here represented by the ORB line.12 The cranial base shape or, to be exact, the shape of the midline cranial base has been found to be relatively stable in cross-sectional studies, although longitudinally conducted investigations have revealed some age changes in angular relationships.ll *Tlop ** It is not surprising, therefore, that the present study also
Variability reveals an unchanging
of
craniofaciu.1
skeleton
41
complex within the cranial base, consisting of the lines and FOR. The stability of the nasal floor in relation to the cranial structures has been observed in the past.3, I3322 It is confirmed at present by the parallelism between the lines SPHEN and PAL in both age groups and by the very low variability of this angle in both samples. The SPHEN line seems to represent fairly well the olfactory area recently pointed out as a determining arca for the arrangement of the facial skeleton.” However, the roof and the floor of the nasal chamber are parts of the larger nasopharyngeal complex which, on an average, was also found to be relatively stable (Fig. 2) in agreement with many previous studies 1, 9, 16,2%22,28 The occlus~.l plane seems to occupy a special place in the ranks of the plants studied. Its variability is very low, and it has only one unchanging angular rclationship (in cross-sectional terms), with the anterior part of the mandibular canal. The position of the occlusal plane, recently the subject of an interesting study and discussion,Z” can be described as being a plane around which most other planes rotate during growth, keeping their mutual relations to it still relatively invariable. Further support was found in this study for the suggested close relationship between the occlusal plane and the mandibular canal.‘* Likewise, the earlier observation that the mandibular canal is more closely associated with the mandibular body than with the ramus or the condyle seems to be confirmed by the present results. The relatively loose association between the horizontal and the vertical rami of the mandible has been known for a long time”? l-1>I53I8 and has been confirmed in several recent biometric and experimental investigations.3, 5, I29 I71I9 The ramus appears to have a dual function as a link between the tooth-bearing body of the mandible and the skull and as a protective wall of the pharynx, and the condyle is the most adaptive part of the link12; similar suggestions have been made by other authors.3s I9 It has been stated also that the remodeling of the ramus is dependent on the growth direction of the condyle.Y However, causal dependency cannot be proved by numerical associations, and it could be just as logically argued that the condylar growth is dependent on the growth direction of the ramus. Actually, in view of both biometric and experimental evidence available, it seems that the condyle, ramus, and other functional parts of the mandible depend in their postnatal growth not so much on each other as on some outside factors, which remain unidentified at the present time. When the variances related to the fourteen lines are summed up, the totals in the two groups are found to be within 10 per cent of each other. The assumption that the structural variability increases with age is thus not supported by the present figures. Some of the lines change their position along the variability scale with age in our cross-sectional terms. For instance, the variability of the angular relationships of CLIVUS and PHAR with other lines increases with age in almost every instance; the exceptions are the angles CLIVUS/RAMUS, CLIVUS/COND, CLIVUS/PTER, PHW’SPHEN, and PHAR/RAMUS; that is, the pharyngeal complex is found here ORB,
SPHEN,
CLIVUS,
PHAR,
42
Viwkka a.nd Koslci
Am.
J. Orthod.
.?nnunry1975
again. T-, at first glance, seem confusing. Perhaps this overlapping is indicative of multidirectional connections within a holistic system7? In other words, when w’t look for factors, structural or functional, which govern the growth of the components of the craniofacial skeleton, we should be aware of the possibility that, for each part there may exist several potential “governors” which may exercise their influence singly or jointly, depending on prevailing circumstances. Furthermore, what is a governed part in one pattern may be a “governor ” in another combination or at another time. Summary
Samples of lateral s-ray cephalograms of forty young girls and forty young female adults were analyzed by a previously described mrthod. Many of the findings made in an earlier study on a sample of dry skulls of children were supported by the present findings. Several similar configurations among the x-ray anatomic lines were found in the two age groups. These configuratiorts suggest cert,ain functional associations between craniofacial components. They also lend support to the holistic view of the craniofacial biology. This Turku
study Research
has been supported Fund (H. V.) , and
by grants the Academy
from the Institute of Finland (K.
of K.)
Dentistry, .
University
of
Varitrbility
of cramiofacinl
skeletm
43
REFERENCES
1. B~~rghtnd, 0. : The bony nasopharynx, Acta Odontol. Scmd. 21: Supp. 35, 1963. 2. Bjork, A.: The face in profile, Lund, 1947, Berlingska Boktryckeriet. 3. Rjijrk, A., and Skieller, V. : Facial dwc~lopmerrt and tooth wuption, AM. J. OKTIIOD. 62: x39-‘383 t ,* 1072. 4. Bjiirk, A., and Holow, H.: Measurement on radiographs, J. Dent. Res. 41: 672683, 1962. 5. lhO\\-11, T.: Skull of the Australian aboriginal, Thesis, University of Adelaide, 1967. 6. Cleaver, F. FT.: A caontribution to the biometric study of the human mandible, Biometrika
29:
80-112,
1937.
7. Dullrmrijer, P. : Methodology in craniofac-ial biology, Actn Morphol. Neerl. Stand. 10: P-23, 1972. 8. Enlo\\-, I). II., and McNamura, *J. A., Jr. : The neurocrunial basis for facial form and pattern, Angle Orthod. 43: 256-270, 1973. 9. Horowitz, H. I,., Osborne, B. H., and DrGeorge, F. V.: A cephalomctric study of erxniofacial variation in adult twins, Angle Orthod. 30: l-5, 1960. 10. Koski, K.: Growth changes in the relationships between some basicranial planes and the pnlatal phtnr, Suom. Hammasl%ik. Toim. 57: 15-26, 1961. 11. Koski, K.: The Finnish female face in norma lateralis, Trans. Eur. Orthod. Sot. 1964, pp. 463.46Q, 1965. 12. Koski, K.: Variability of the crxniofacinl skeleton, Aor. J. ORTHOD. 64: 188-196, 1973. 13. Koski, K., and Virolninen, K.: Relation of the His’ lint to the nasal floor, Dent. Rec. 75: 45-50, 1955. 14. Mnj, G., and Luzi, C.: Analysis of mandilmlar growth on 28 normal children followed from 9 to 13 years of age, Trans. Eur. Orthod. Sot. 1962, pp. 141-158, 1963. 15. Maj, G.: 1%synchronism in growth of the mandible, Trans. Eur. Orthod. Sot. 1968, pp. 83-93, 1969. 16. Melsen, B.: A radiographic craniometric study of dimensional changes in the nasal septum from infancy to maturity, Acta Odontol. &and. 25: 514-561, 1967. 17. Moorr, W. J.: An experimental study of the functional components of growth in the rat mandible, Aeta Anat. 85: 378-385, 1973. 18. Morant, G. M.: A biometric study of the human mandible, Biometrika 28: 84-122, 1936. 19. Moss, M. L.: Functional cranial analysis of mammalian nrnndibular ramal morphology, Actu Andt. 71: 423-44i, 1968. 20. MOSS, M. L., and Salentijn, L.: The capsular mat,rix, Aai. J. ORTHOD. 56: 474-490, 1969. 21. MOSS, M. L., and Salentijn, I~.: The logarithmic growth of the human mandible, Acta Anat. 77: 341-360, 1970. 22. Schouboe, Ii., and Hauge, M.: The application of twin methods in orthodontic research, Stand. J. Dent. Res. 81: 563-566, 1973. "3. Solom, B.: The pattern of craniofacial association, Actn Odontol. &and. 24: Supp. 46, 1966. 24. Stramrud, L.: External and internal cranial base, Acta Odontol. &and. 17: 239-266, 1959. 25. Vinkkx, H.: Kallon luuston rakenteen vaihtelevaisuus, Proc. Finn. Dent. Sot. 68: 171, 1972. 26. Vinkka, II., and Koski, K.: Interand intraobservrr variability in an x-ray craniometric analytical method, Proc. Finn. Dent. Sot. 70: 156.160, 1974. 27. Vinkka, H., Koski, Ii., and McXamara, J. A., Jr.: Unpublished data. 28. Zingeser, M. R.: Nasomnxillary proportional constancy, AM. J. ORTHOR 46: 674.684, 1960. 29. Zingeser, M. R. : Occlusofaeinl morphological integration, Fourth International (‘ongress of Primatology, vol. 3. Craniofacial biology of Primates, Bawl, 1973, S. Knrger, pp. 241-257. Lernminkiiisenkatzc
20580 Turku 51 Finland
2
Vinkka,
LOdont.,
and
Kalevi
Koski,
D.Odont.*
Pidand
lTurku,
T
he variability of the craniofacial skeleton was recently analyzed in a sample of child skulls.” The analytical method was constructed to focus on some presumabl>- meaningful anatomic relationships. The sample was selected not only according to age but also on the basis of occlusal normality. At the time of collection of the infant skull material, a very small samplr of adult skulls was also available. I’rcliminary observations from the two samples indicated that the application of the method to a coniparat,ive study on different age groups might bc rewarding, and the present stutly was therefore undertaken. Muterial
and
methods
The material consisted of two samples of lateral s-ray cephalograms, forty in each sample. The first sample was from a collection of ccphalograms of Finnish schoolgirls, 6 to 8 years of age, radiographed without selection.“’ The second sample was drawn from a collection of radiograms of Finnish fcmalr dental ‘~1 to 28 scars, also taken without selection.” A st,andardized studrnts, aged __ tcchniyuc dcscribctl it) the original publications was used. The method of analysis was essentially the same as in the previous study,” but two new lines were added to the original twelve lines’” (Fig. 1). The mutual angular relationship of thcsc fourtccti lines were studied. Since it was obvious that the definition of some of the lines would be tiiffieult in some instances. both of us c~hcckctl through tht> whole material togct’hcr, determining how the lines should bc visnalizcd. Thcreaftcr, the first author alone measured the material. [Ysing tracing sticcts pln~ecl on the films, the lines w’cro drawn to the anatomic lengths of the structures to b(> rcpresentetl ant1 were not estcndcd to uoss each other. Tn casts of double images in the films, the lines wcr”c drawn to rcprescnt the geometric means of the double images. A large, speciall) made protractor, equipped with a movable indicator ilrtn, was used to measure the angles formed by the line ORB with all the other lines, tllatI is, a set of thirteen “Chairman, University
34
Department of Turku.
of
Pcdodontics
and
Orthodontics,
Institute
of
Dentistry,
Variability
Fig.
1. The
lines
used
in the
analysis:
1, Tangent
to the
of craniofacial
posterior
slope
of the
skeleton
orbital
35
roof,
ORB; 2, tangent to the spheno-ethmoidal line, SPHEN; 3, line depicting the infraorbital canal, INFRA; 4, tangent to the nasal floor posterior to the incisal canal, PAL; 5, occlusal line, through the most anterior and posterior contact points between the upper and lower deciduous molars/premolars and first permanent molars, OCCL; 6, line depicting the anterior part of the mandibular canal under the occlusal line, AMC; 7, tangent to the mandibular base, MAND; 8, line depicting the posterior part of the mandibular canal, PMC; 9, tangent to the posterior border of the ramus, condylar process excluded, RAMUS; 10, tangent to the posterior border of the condylar process, COND; 11, tangent to the cerebral surface of the clivus, dorsum sellae excluded, CLIVUS; 12, tangent to the ventral surface of the pterygoid process, PTER; 13, tangent to the pharyngeal surface of the clivus, PHAR; 14, the foraminal line, opisthion-basion, FOR.
angles. The angular relationships between the rest of the lines were then calculated, thus obtaining figures for a total of ninety-one angles between the fourteen lines. The readings were taken to the nearest 0.5 degrees. The majority of the angles were measured or calculated as opening ventrally, and only in instances where this would have led to values greater than 180 degrees was the dorsally opening angle recorded. The statistical treatment of the recorded and calculated values included the computation of means and variances and the testing of their differences by using the t test resp. the F test.
The means and variances of the angles between the fourteen lines in both age groups are given in Tables I and II.
36
l’ixkka
Table
I.
Koski
and
Means
and /
variances ORB
of SPIIEN
angles
/ 11VFRA
"5.3
ORB
in
a
PAL
j
sample
of
forty
OCCL
/
AMC
child
x-ray
1 MANI)
4!).3
22.4
36.8
50.2
51.0
23.9
3.0
Il.5
L’5.:
26.9
12.4
24.9 0.9 27.x
1.7
13.4
14.2
SPHEiY
12.6i
ISFRA
32.00
26.40
PAI,
14.86
20.77
o(‘cr,
16.19 '5.62
20.99
26.39
13.21
AM (’
:16.65
35.05
30.33
27.84
15.22
3IAND
39.98 26.19
34.24
32.67
24.15
13.41
7.51
22.19
24.28
12.41
14.45
23.99
32.51
41.06
34.30
35.11
49.50
43.99
COND
31.31 33.20
38.59
29.60
31.13
34.93
39.51
PTER
48.71
53.85
32.89 36.30
36.17
31.16
48.02
45.54
CLIVUS
23.78
22.35
14.46
21.81
37.69
34.90
PHAR
34.86
21.2i 40.88
36.91
24.82
32.63
48.95
47.94
FOR
38.86
39.30
21.32
23.88
25.40
45.71
43.42
PM< RAMUS
The
underlined
Table
II.
means
Means
and
do not
differ
variances ORB
from
of
craniofacial
25.4
PAL
18.55 15.97
OCCL AMC MAND
INFRA
adult
angles
INFRA 45.5 20.1
5.84
SPHEN
14.4
the corresponding
SPHEN
ORB
The
craniofacial
18.03
1
in
means
a
28.6 0.8
(p <
17.47
0.01 j.
sample
of
forty
PAL
OCCL
)
AiW
24.1 1.3
30.0 4.6
42.5
47.8
17.0
22.4
2iz
15.5
-3.0 18.4
2.4 2E
12.4
17.8
5.9
adult
x-ray
] MAND
15.15
16.03 14.07
"1.79 17.18
13.26
40.77
39.86
37.03
45.86
21.22
34.50 25.48
27.06 19.04
36.44
16.57
6.20
PMC
33.99 27.27
24.08
23.94
18.44 15.27
20.40
26.74
18.20 18.03
26.87
RAMUS
43.31
32.72
COND
33.32
43.35
36.92
31.59
37.44
66.35
53.59
PTER
31.53
35.78
33.52
28.48 31.41
42.82
34.27
67.36
52.34
-
5.4
CLIVUS
36.92
37.10
46.17
27.71 25.06
PHAR
51.55
43.42
61.31
44.21
38.95
84.72
70.07
FOR
21.85
24.28
32.47
29.62
26.42
58.09
50.11
underlined
means
do
not
differ
from
the
corresponding
child
means
(p
<
0.01).
It appears that forty-seven of the ninety-one angles are not, on an average, statistically different in the two age groups, at the 0.01 risk level (t = 2.640). The smallest difference between means is 0.1 degree (ORB/SPHEN) ; the largest, 12.4 degrees (AMQ'PTER). The average figures indicate that several line patterns are similar in both age groups (Figs. 2 to 4). If the combination OCCL/AMC (these two lines have only this one mutual unchanging relationship) is omitted, the patterns can also be schematized in Chart 1. Several parallelisms, within 5 degrees from 0, were found between pairs of lines in the two age groups; four of these were the same in both groups. The angle INFRA/AMC had statistically different means in the two groups, but this
Variability
of waniofacia~l skeleton
37
cephalograms PMC
RAMUS
87.1 -
105.5
61.8
80.1
(
COWD -89.7 64.4
1
(
PTER
CLZPUS
PHAR
FOE 15.0
91.8
140.0
5.8
66.4
114.7
148.9
10.3
37.9
58.2
40.4
42.5
90.8
125.0
34.2
64.7 50.3
83.1 68.6
112.7
110.6
62.4
28.2
127.2
125.1
'i6.8
42.6
7.4 eix
143.1
124.7
140.5
138.4
89.8
56.0
143.9
125.5
141.3
139.2
5'6.8 92.9
18.4 28.52
35.2 36.0
2.6
4.7
91.0 127.1
-15.8
13.7
145.4
111.2
xi-
129.7
95.5
105.3
48.2
82.5
103.2
34.2 -
125.0
25.96
-
37.75
51.50
41.61
69.12
42.44
20.52
31.80
45.28
41.85
36.46
46.34
53.61
48.03
13.44
26.87
47.48
51.07
30.79
16.25
lo'i.9 89.6
159.2
cephalograms PMC
RAMUS
COND
PTER
85.1 59.6
108.2 82.8
91.8
96.5
140.2
66.4
71.1
39.6 61.0
62.8
46.3
51.0
114.7 94.7
149.1 129.0
84.1
112.3
107.6
55.0
78.2
118.3
113.5
-63.9 69.9
29.5 35.5
1ZZ
137.4
114.2
130.7
126.0
97.7
47.9
26.9
142.8
119.6
136.1
131.4
87.7
53.3
32.2
11.4
124.9 148.1
90.5 113.7
110.5
131.6 43.7
97.2 78.1
103.8
34.4 -
124.6
23.2 22.13
6.7 18.5 -
11.8 47 A
(
CLZVUS
37.35
40.73
23.82
33.60
32.95
38.83
38.28
54.56 39.56
42.51 30.75
46.53 62.76
29.78 58.44
21.75
48.75
37.96
34.26
1
PHAR 5.4
FOR 15.5 9.9 2G 8.6
87.3
99.1 159.0
49.32
angle fluctuates around 0, and the average parallelism still existed. This became clear when all the infraorbital and mandibular canals were drawn on the same paper, superimposing on the short, straight infraorbital canals (Fig. 5). A number of angles were within 5 degrees of 90 degrees, and again some of these were the same in both age groups. The variability of the angular relationships, expressed by the variances, can be inspected both within the total framework and by detail relationships. When the variances for each line are totalled, it can be seen that the order and range of values are different in the two age groups. Certain lines are involved in relationships of low variability in both age groups: PAL, OCCL, PMC, SPHEN, ORB, INFRA. The line COND has a large total variance in both age groups.
Fig. 2. Two patterns two age anatomic
groups, structures
of at
lines
whose
the 0.01 risk are illustrated.
mutual angular relationships level; instead of the actual
are lines,
in the not different the corresponding
ORB SPHEN .
. .
PAL .
.
.
INFRA .
.
.
. .
.
.-.-. .
MAND .
. -
pMC -
:
.
RAMUS
.
.
COND
.
.
.
.
PTER
.
CLIVUS
.
PHAR
PHAR
FOR CHART
1.
It may also be noticed how the CLIVUS, AMC, and PHAR lines become more variable when we move from the child sample to the adult one, whereas the lines RAMUS and PTER do just the opposite. Both ends of the mandibular canal, AMC and PMC, have their least variable relationship within the mandible with the MAND line and the most variable one with the line COND; the differences are statistically significant in both age groups (p < 0.05,F = 1.70). The AMC/RAMUS angle has a significantly larger variance in both age groups than the AMC/MAND angle (p < 0.01, F = 2.13). The RAMUS/ COND angle variance is nearly the largest of all variances involving the ramus in both age groups,
Variability
fig. 3. Two more patterns of lines whose mutual angular in the two age groups, at the 0.01 risk level, drawn to involved.
of craniofacial
relationships indicate the
skeleton
39
are not different anatomic structures
The variances related to the OCCL line are also interesting. The smallest variance in both age groups is found for the OCCL/PAL angle, but the occlusal plane seems to have relatively small variability to the mandibular body and canal (MAND resp. AMC, PMC) also, whereas its relationship with the condylar process (COND) is greatly variable. The OCCL/RAMUS angle has a large variance in the child group, but one of the smallest in the adult group. Discussion
From the technical point of view, mcasurcments on roentgen films should be taken directly from films, using clearly definable points and connecting lines and observing some other pertinent details.‘, 4, 23 In the present study the conceptual basis of the analysis has not permitted the ideal procedure. It has been shown elsewhere, however, that the methodologic error which represents the intraobserver error is within acceptable limits.2G The average parallelism between the infraorbital canal and the anterior part of the mandibular canal, found in the first study,12 was seen in the present two samples also. It can be mentioned here that the same relationship has been found also in young macaca monkeys. 27 The fact that the angular relationship between the infraorbital canal and the posterior part of the mandibular canal is different in the two age groups is readily explained by the size differcncc; the general form of the mandibular canal, stated to be a logarithmic spiral,2f seems remarkably constant (Fig. 5). The parallelism between the posterior part of the mandibular canal and the condyle (PMC/COND) , found here in children but not as clearly in
Fig. 4. The fifth level, illustrating
pattern of similar configurations the anatomic structures.
Fig. 5. The infraorbital and imposed on the infraorbital the right.
mandibular canals. The
in
both
canals drawn from child sample on the
age
the left
groups,
two and
at
the
samples the adult
0.01
risk
and supersample on
adults, is interesting since the spatial relationship between these two elements in human fetuses seems to be a close one.zi The present findings support the notion that the pterygoid process and the condylar process have a biologically meaningful perpendicular relationship to the lateral cranial base, here represented by the ORB line.12 The cranial base shape or, to be exact, the shape of the midline cranial base has been found to be relatively stable in cross-sectional studies, although longitudinally conducted investigations have revealed some age changes in angular relationships.ll *Tlop ** It is not surprising, therefore, that the present study also
Variability reveals an unchanging
of
craniofaciu.1
skeleton
41
complex within the cranial base, consisting of the lines and FOR. The stability of the nasal floor in relation to the cranial structures has been observed in the past.3, I3322 It is confirmed at present by the parallelism between the lines SPHEN and PAL in both age groups and by the very low variability of this angle in both samples. The SPHEN line seems to represent fairly well the olfactory area recently pointed out as a determining arca for the arrangement of the facial skeleton.” However, the roof and the floor of the nasal chamber are parts of the larger nasopharyngeal complex which, on an average, was also found to be relatively stable (Fig. 2) in agreement with many previous studies 1, 9, 16,2%22,28 The occlus~.l plane seems to occupy a special place in the ranks of the plants studied. Its variability is very low, and it has only one unchanging angular rclationship (in cross-sectional terms), with the anterior part of the mandibular canal. The position of the occlusal plane, recently the subject of an interesting study and discussion,Z” can be described as being a plane around which most other planes rotate during growth, keeping their mutual relations to it still relatively invariable. Further support was found in this study for the suggested close relationship between the occlusal plane and the mandibular canal.‘* Likewise, the earlier observation that the mandibular canal is more closely associated with the mandibular body than with the ramus or the condyle seems to be confirmed by the present results. The relatively loose association between the horizontal and the vertical rami of the mandible has been known for a long time”? l-1>I53I8 and has been confirmed in several recent biometric and experimental investigations.3, 5, I29 I71I9 The ramus appears to have a dual function as a link between the tooth-bearing body of the mandible and the skull and as a protective wall of the pharynx, and the condyle is the most adaptive part of the link12; similar suggestions have been made by other authors.3s I9 It has been stated also that the remodeling of the ramus is dependent on the growth direction of the condyle.Y However, causal dependency cannot be proved by numerical associations, and it could be just as logically argued that the condylar growth is dependent on the growth direction of the ramus. Actually, in view of both biometric and experimental evidence available, it seems that the condyle, ramus, and other functional parts of the mandible depend in their postnatal growth not so much on each other as on some outside factors, which remain unidentified at the present time. When the variances related to the fourteen lines are summed up, the totals in the two groups are found to be within 10 per cent of each other. The assumption that the structural variability increases with age is thus not supported by the present figures. Some of the lines change their position along the variability scale with age in our cross-sectional terms. For instance, the variability of the angular relationships of CLIVUS and PHAR with other lines increases with age in almost every instance; the exceptions are the angles CLIVUS/RAMUS, CLIVUS/COND, CLIVUS/PTER, PHW’SPHEN, and PHAR/RAMUS; that is, the pharyngeal complex is found here ORB,
SPHEN,
CLIVUS,
PHAR,
42
Viwkka a.nd Koslci
Am.
J. Orthod.
.?nnunry1975
again. T
Samples of lateral s-ray cephalograms of forty young girls and forty young female adults were analyzed by a previously described mrthod. Many of the findings made in an earlier study on a sample of dry skulls of children were supported by the present findings. Several similar configurations among the x-ray anatomic lines were found in the two age groups. These configuratiorts suggest cert,ain functional associations between craniofacial components. They also lend support to the holistic view of the craniofacial biology. This Turku
study Research
has been supported Fund (H. V.) , and
by grants the Academy
from the Institute of Finland (K.
of K.)
Dentistry, .
University
of
Varitrbility
of cramiofacinl
skeletm
43
REFERENCES
1. B~~rghtnd, 0. : The bony nasopharynx, Acta Odontol. Scmd. 21: Supp. 35, 1963. 2. Bjork, A.: The face in profile, Lund, 1947, Berlingska Boktryckeriet. 3. Rjijrk, A., and Skieller, V. : Facial dwc~lopmerrt and tooth wuption, AM. J. OKTIIOD. 62: x39-‘383 t ,* 1072. 4. Bjiirk, A., and Holow, H.: Measurement on radiographs, J. Dent. Res. 41: 672683, 1962. 5. lhO\\-11, T.: Skull of the Australian aboriginal, Thesis, University of Adelaide, 1967. 6. Cleaver, F. FT.: A caontribution to the biometric study of the human mandible, Biometrika
29:
80-112,
1937.
7. Dullrmrijer, P. : Methodology in craniofac-ial biology, Actn Morphol. Neerl. Stand. 10: P-23, 1972. 8. Enlo\\-, I). II., and McNamura, *J. A., Jr. : The neurocrunial basis for facial form and pattern, Angle Orthod. 43: 256-270, 1973. 9. Horowitz, H. I,., Osborne, B. H., and DrGeorge, F. V.: A cephalomctric study of erxniofacial variation in adult twins, Angle Orthod. 30: l-5, 1960. 10. Koski, K.: Growth changes in the relationships between some basicranial planes and the pnlatal phtnr, Suom. Hammasl%ik. Toim. 57: 15-26, 1961. 11. Koski, K.: The Finnish female face in norma lateralis, Trans. Eur. Orthod. Sot. 1964, pp. 463.46Q, 1965. 12. Koski, K.: Variability of the crxniofacinl skeleton, Aor. J. ORTHOD. 64: 188-196, 1973. 13. Koski, K., and Virolninen, K.: Relation of the His’ lint to the nasal floor, Dent. Rec. 75: 45-50, 1955. 14. Mnj, G., and Luzi, C.: Analysis of mandilmlar growth on 28 normal children followed from 9 to 13 years of age, Trans. Eur. Orthod. Sot. 1962, pp. 141-158, 1963. 15. Maj, G.: 1%synchronism in growth of the mandible, Trans. Eur. Orthod. Sot. 1968, pp. 83-93, 1969. 16. Melsen, B.: A radiographic craniometric study of dimensional changes in the nasal septum from infancy to maturity, Acta Odontol. &and. 25: 514-561, 1967. 17. Moorr, W. J.: An experimental study of the functional components of growth in the rat mandible, Aeta Anat. 85: 378-385, 1973. 18. Morant, G. M.: A biometric study of the human mandible, Biometrika 28: 84-122, 1936. 19. Moss, M. L.: Functional cranial analysis of mammalian nrnndibular ramal morphology, Actu Andt. 71: 423-44i, 1968. 20. MOSS, M. L., and Salentijn, L.: The capsular mat,rix, Aai. J. ORTHOD. 56: 474-490, 1969. 21. MOSS, M. L., and Salentijn, I~.: The logarithmic growth of the human mandible, Acta Anat. 77: 341-360, 1970. 22. Schouboe, Ii., and Hauge, M.: The application of twin methods in orthodontic research, Stand. J. Dent. Res. 81: 563-566, 1973. "3. Solom, B.: The pattern of craniofacial association, Actn Odontol. &and. 24: Supp. 46, 1966. 24. Stramrud, L.: External and internal cranial base, Acta Odontol. &and. 17: 239-266, 1959. 25. Vinkkx, H.: Kallon luuston rakenteen vaihtelevaisuus, Proc. Finn. Dent. Sot. 68: 171, 1972. 26. Vinkka, II., and Koski, K.: Interand intraobservrr variability in an x-ray craniometric analytical method, Proc. Finn. Dent. Sot. 70: 156.160, 1974. 27. Vinkka, H., Koski, Ii., and McXamara, J. A., Jr.: Unpublished data. 28. Zingeser, M. R.: Nasomnxillary proportional constancy, AM. J. ORTHOR 46: 674.684, 1960. 29. Zingeser, M. R. : Occlusofaeinl morphological integration, Fourth International (‘ongress of Primatology, vol. 3. Craniofacial biology of Primates, Bawl, 1973, S. Knrger, pp. 241-257. Lernminkiiisenkatzc
20580 Turku 51 Finland
2