Occlusal and craniof acial growth changes during puberty Hideo
Mitani,
D.D.S., MS.,
D.D.k.
Tokyo, Japan
S
ince the human skull is essentially divided into two bones, i.e., the mandible and the rest of the head (craniomaxillary bone) ,I the maxillary dental arch is considered to be fixed to the cranium with the nasomaxillary complex and thus immobilized, whereas the mandible is a single bone which is the movable component in mastication. Therefore, the maxillary dentition seems to be governed by the growth of the craniomaxillary complex, while the mandibular dentition is carried in a general downward and forward direction by growth on the posterior border of the ramus and top of the condyle. Viewed in this manner, the balanced occlusion would imply that the morphogenetic pattern of each facial component and its growth and development are also so synchronized that they maintain a reasonable proportion of size and form together with a proper spatial relationship of the basal bones of the upper and lower dentitions.2 This primarily requires the synchronization of the growth of the craniomaxillary complex and mandible in rate and time of growth, sequences, and size attainment as a whole. However, facial bones and areas to which they contribute show wide ranges of variability in these matters, and the variants are not always in the same direction .3 Therefore, the lack of synchronization among them will cause a dysplastic facial pattern in all or some of the components, unless the variants compensate each other to some degree.4r h Thus, the proper occlusion of teeth would reflect the result of the dynamic as well as the static synchronization or compensation of the growth which each face confronts. However, growth of the craniomaxillary complex and the mandible with the mixtures of cartilaginous component (cranial base synchondrosis, nasal septum, and mandibular condyle) and of membranous elements, all under the control or influence of morphogenetic factors or function, is still not completely understood.6 This means that the growth of the mandible and the craniomaxillary complex could be considered to be governed by different growth mechanisms of From
76
the
Department
of
Orthodontics,
Tokyo
Medical
and
Dental
University
Pdxrtnl
Fig. 1. Tracing ployed in this
of lateral study.
changes itr occlusal and crakfacial
cephalometric
roentgenograms
showing
points
growth
and
planes
77
em-
the head skeleton, if any. These different growth mechanisms would underlie the pattern of the whole development and the spatial relationship of the dentures. Therefore, the occlusion of the teeth could help one determine whether or not the facial skeletal pattern and its growth and development have been balanced (either synchronized or compensated) as a whole in the growing process. However, the growth process in any person is continuous ; its state changes continuously over time and demonstrates distinct characteristics. Particularly at puberty, it is commonly recognized that remarkable growth takes place in the face as well as in body height and weight, and the occlusion of the permanent den& tion is mainly accomplished during this period. The present investigation was undertaken to gain further insight into the role of facial growth in establishing a proper relationship of occlusion by studying the growth changes of several facial components during puberty. Materid
Materials used in this study were composed of an B-year series of lateral cephalometric roentgenograms of thirty Japanese children (seventeen boys and thirteen girls). Each series was taken annually between the ages of 7 (6.5 to 7.7) and 15 (14.5 to 15.8) years. For two boys the films from the initial year were missing, and in another case the film from the last year was missing. The sample consisted of a random selection of skeletal patterns, the choice of material being based solely an age and on the quality of roentgenograms. However, since certain types of facial growth may be associated with a tendency toward certain kinds of malocclusion, the cases were limited to those with normal occlusion or minor Class I malocclusion. None of the subjects underwent orthodontic therapy. All materials were obtained from the files of the Department of Orthodontics, Tokyo Medical and Dental University.
78
Mitani
Am.
J. Orthod. July 1977
Method
Lat,eral cephalometric films were traced. The method of gaining measurements was based mainly on Coben’s coordinate system in which the Frankfort horizontal plane was employed as a plane of orientation. 4 Fig. 1 illustrates the points and planes used in this study and shows a diagram of the method of measurement. Measurements of craniofacial depth were taken parallel to the Frankfort plane; vertical height was measured along lines perpendicular to Frankfort. Some measurements, however, were made directly between two points to avoid the effect of angular change in length during growth when projected to the Frankfort plane. For instance, Ar-Pog could show decreased length between two different stages when measured on the Frankfort plane if its angle to FH were increased. The following measurements were used, and they were divided into two groups for the purpose of this study. Group A measurements were taken from the craniomaxillary complex, and Group B were from mandible. Group A: Ba-N, Ba-S, N-Ans, S-Ar, Ba-A, X-N Group B : ilr-Pog, Ar-Go, Go-Pog, M-L1 (Italics
indhte
direct measurement.)
A set of growth increment data constitutes a discrete time series which shows the state of a process at several points in time. The process is described by combining each point as a curve if it shows the changes in the incremental ratio. This was gained by the percentage ratio of an annual increment to the total in this study and combining each point was made by the French curves. Mean curves of the craniomaxillary group and the mandibular group were obtained individually by averaging each value at each age. Then, each curve was examined with respect to the following points : 1. Timing of occurrence of the growth spurt between two groups. 2. Ages at occurrence of the growth spurt, 3. Correlation of each process of changing rate between two groups. 4. Synchronization of timing of changing rate between two groups. The correlation coefficients between two curves were determined to examine the synchronization of each process of the changing rate. Mean curves of two groups were applied to the statistical manner of time lag correlation. Time lag correlation in this study means the method of analysis of time correlation of growth pattern between the craniomaxillary group and the mandibular group by a unit of annual lag. I8 For the examination of statistical significance of correlation coefficients, a 10 per cent level of probability was used because of the small numbers of the measurement interval. Results
Individual mean curves of growth rate of two groups are shown in Figs. 2 and 3. Distribution of age at occurrence of the maximum growth peaks is summarized in Fig. 4. The time lag correlation coefficients between two groups were obtained individually to examine the synchronization of each process of the changing rate. The results are shown in Table I. The maximum annual increment and the total increment of each component during the period studied are shown in Table II.
Pubertal
chavzges in occl~csal and craniofacial
growth
79
0 10 0
8
9
10
11
12
13
14
15
ape
10 0
7
8
9
10
Fig. 2. Male individual craniomaxillary group. mum peak rate.
11
13
12
curves Broken
of line:
14
growth Mean
-5'w rate curve
(percentage). of mandibular
Solid line: Mean group. Arrowhead:
curve of Maxi-
Discussion
The biologic environment of the dentofacial region consists of various orders, such as the morphogenetic, physiologic, functional, etc., which govern the skeletal and nonskeletal patterns of the face as well as its growth and development. The lack of balance and harmony among them will cause the dysplastic pattern on the face in all or some of the components. This has been considered as the cause
Am.
I
I
7 Fig.
8 3.
9
Female
craniomaxillary Maximum
peak
10 individual group. rate.
11
12 curves Broken
13 of line:
14
15
growth Mean
I 9
8
I
I 10
6. Orthod. July 1957
I
I
ace
11
12
13
Solid
line:
Mean
14
15 -
age
rate
(percentage).
curve
of
mandibular
group.
curve
of
Arrowhead:
of malocclusion. Since there are wide variations of facial growth in amount, timing, rate, and direction, no two faces would ever show an identical form of growth pattern. Therefore, the balanced face will include a very wide range of facial types, and variability is seen not only in racial characteristics but also within each of the racial groups and their various subdivisions.15 Furthermore, faces exhibiting malocclusion vary from those with a comparatively good skeletal balance to those with a severely unbalanced pattern. This is due to the variation of each order. In the present study, each growth curve of the craniomaxillary group and the mandibular group represented various types of peak velocity which indicate that the growth rate was accelerated and then decelerated. Among several peaks in each curve, the maximum peak was indicated by a small arrowhead in Figs. 2 and 3, and this was mostly taken to indicate the puberal growth spurt. The growth spurt in the face during puberty has been reported by many investi-
age
,lOel 00 :oO 00
female
l craniomaxillary Omandibular Fig.
4.
Table
Age
distributions
I. Time
mandibular
lag
of
occurrence
correlation
group
group
of
of
the
growth
growth
rate
between
spurt
(maximum
annual
craniomaxillary
group
increment).
and
group
Year lime
lag
-2
-1
+J
16 B 17 Total
*Significant iSignificant $Significant
-I
0
4-l
+2
Gl
G2 G3 G4 GS G6 G7 G8 G9 G 10 G 11 G 12 G 13
0.786* 0.702* 0.698* 0.701;
IO II 12 13 14 15
-2
+2
0.763t
Bl
B2 B3 B4 B5 B6 Bl B8 B9 B B B B B B B
0
0.740t 0.736t 0.749*
o&50* 0.7 lot 0.783t 0.729* 0.809t 0.9295 0.839$ 0.850t
0.8.54t
1
I
0.881$ 0.821t 8
1
0
0
I
5
2
0
at the 10 per cent level of probability. at the 5 per cent level of probability. at the 1 per cent level of probability.
gators7-14 A spurt occurred on the endocranial base (Ba-S) and the maxillary complex, as well as the mandible, of both boys and girls.17y I8 As for the timing of occurrence of the maximum peak between two groups, eleven out of seventeen boys (64.7 per cent) and seven out of thirteen girls (53.8 per cent) coincided. Therefore, on the average, approximately 60 per cent of the sample (eighteen of thirty) showed coincidence of timing of the maximum peak occurrence. This
Am.
Table
II.
Total
increment
and Total
maximum
increment
Ba-N Ba-S S-N N-Am S-AT Ba-A Ar-Pog Ar-Go Go-Pog M-L1
15.2 10.3 7.5 11.4 8.6 12.7 20.7 12.5 17.2 9.1
increment
(mm.)
Male Mean
annual
of Maximum
Female S.D.
2.8 1.8 2.2 2.1 2.0 2.8 3.6 3.6 3.2 1.7
Mean
11.7 7.5 5.5 8.7 6.4 10.3 17.4 9.6 13.3 8.0
1
each
component annual
increment
Male SD.
1.7 1.7 I .4 1.6 1.8 I.7 1.9 2.2 2.1 1.7
Mean
3.6 2.7 1.7 2.4 2.4 3.2 4.6 3.8 4.1 2.6
J. Ortkod. July 1977
(mm.) Female
( S.D.
0.8 0.8 0.7 0.4 0.5 0.8 0.8 0.9 1.1 0.7
Mean
3.4 2.3 1.6 2.6 2.3 2.6 4.3 2.8 3.6 2.0
S. D.
0.6 0.6 0.4 I.0 0.9 0.7 I.2 0.7 0.7 0.4
seems to indicate that the pubertal growth spurt will occur predominantly at the same time (year unit) in the whole face. For the age at the maximum peak occurrence, the craniomaxillary group showed ten out of seventeen boys (58.8 per cent) at the ages of 12 and 13 years and ten out of thirteen girls (76.9 per cent) at 10, 11, and 12 years (Fig. 4). The mandibular group also showed its maximum peak mostly like the craniomaxillary group; ten out of seventeen boys (58.8 per cent) at 12 and 13 years and eleven out of thirteen girls (84.4 per cent) at 10, 11, and 12 years. This seems to indicate the average ages at the pubertal growth spurt in the faces of Japanese children. The female growth spurt seems to occur 2 years earlier than the male spurt; therefore, girls tend to mature earlier than boys at puberty, although they exhibited a wider range of variation with respect to the onset of the peak velocity. However, the magnitude of the growth spurt and its total increment are considerably greater in boys than in girls (Table II) .14,‘l Time lag correlation revealed that the growth pattern of the craniomaxillary group and the mandibular group was synchronized in its changing rate in eleven out of seventeen boys (64.7 per cent) and eight out of thirteen girls (61.5 per cent). This means that approximately 63 per cent of the sample showed synchronization of the growth rate pattern between the craniomaxillary complex and the mandible. However, not all of them showed the simultaneity of timing of the changing rates. Among the samples which showed the synchronization of pattern, eight out of eleven boys (72.7 per cent) and’ five out of eight girls (62.5 per cent) showed simultaneity with the age increase. Thus, the synchronization of each process of the changing rate between the eraniomaxillary complex and the mandible appeared at the same year in approximately 43 per cent (thirteen of thirty) of the sample. In Fig. 2, Case B17 shows a typical sample of growth curves in which appeared the synchronization of each process of the changing rates with simultaneous timing per year, and Case G9 in Fig. 3 shows such synchronization but with different timing of growth changes. Although the study was done on a relatively small sample and the result was based on a 10 per cent level of probability for the statistical significance, this
Volume
Number
72
Pubertal
1
changes in occlusal and craniofacial
growth
03
may indicate a tendency of the facial growth at puberty. In other words, the growth of the maxilla and mandible is primarily correlated as a whole in its rate and timing to produce and maintain a proper basal relationship of the dentures. However, this may not always take place in every face. Rate and timing may be only one of the variants which could contribute to a part of the mechanism of compensation or synchronization of various facial components during the growth process, or it may have an independent role in the construction of a dysplastic face pattern or in occlusion. For instance, although the maxilla and mandible may attain the adequate size and be balanced by the end of adolescence, if their growth timing does not synchronize anteroposteriorly during the completion of occlusion, the occlusal relationship of the teeth may be under the influence of a’ tendency toward the Class II or Class III type of basal bone relationship. However, anteroposterior malrelationship of the upper and lower dental arches may not occur on the occlusal level if the tendency is within certain limits. This is because the differing behavior in the direction of inclination of the crown and root of a tooth seems to occur mesiodistally as well as buccolingually during growth,‘” and this behavior may compensate such tendency until the growth is over. Thus, although growth in the face is essential to produce anti maintain a proper dental relationship, it must be kept in mind that the crowns of teeth which belong to the digestive system’” may play a compensative role in the completion of a balanced occlusion. The present study did not deal with the amount and direction of growth of each component, but all samples represented neither vertical nor anteropost,erior discrepancy in occlusion. Since any variation in growth would not exist by itself but would be related to others, every combination of variants should be taken into account in each face when the resulting facial pattern is analyzed. Thercfore, in the samples which did not show a synchronization in growth rate and timing, the amount and direction would have had a chief role in compensation to produce and maintain a proper occlusal relationship in this study. This seems to indicate that the process of construction of a balanced occlusion would imply the necessity of the static (amount and direction of growth) as well as the dynamic (rate and timing of growth) synchronization or compensation of growth in the face. However, individual bones of the body may show different rates of maturation, and rates of maturation may vary from one time to the nextZ2 The statistical method in the present study revealed only a tendency toward synchronization of growth changes, but this tendency was relatively small in degree. However, over-all images of two curves of individuals seem to indicate a basic similarity of trend of growth rate between the craniomaxillary complex and the mandible, although each trend is different and unique in details. If we are to gain further insight into the growth behavior of the maxillary complex and mandible as related to the construction of a proper occlusion, a more criticsal investigation is indicated. REFERENCES
1. Coben, 2. Coben, 3. Brodie,
8. E.: Growth S. E.: Growth A. G.: Facial
concept, Angle Orthod. 31: 194-201, 1961. and Class II treatment, AM. J. ORTHOD. 52: pattern; a theme on variation, Angle Orthod.
5-26,
16:
1966.
l-14,
1946.
Am.
J. Orthod. July 1977
4. Coben, S. E.: The integration of facial variants, Aaa. J. ORTHOD. 41: 407-434, 1955. 5. Enlow, D. H., Kuroda, T., and Lewis, A. B.: The morphological and morphogenetic basis for craniofacial form and pattern, Angle Orthod. 41: 161-188, 1971. 6. Limborgh, J. V.: The role of genetic and local environmental factors in the control of postnatal craniofacial morphogenesis; Mechanism and Regulation of Craniofacial Morphogenesis, Amsterdam, 1972, Swets land Zeitlinger N. V. pp. 37-47. 7. Bushra, E.: Correlations between certain craniofacial measurement, trunk, length, and stature, Hum. Biol. 21: 246256, 1949. 8. Bambha, J. K.: Longitudinal cephalometric roentgenographic study of face and cranium in relation to body height, J. Am. Dent. Assoc. 63: 776-799, 1961. 9. Hunter, C. J.: The correlation of facial growth with body height and skeletal maturation at adolescence, Angle Orthod. 36: 44-54, 1966. 10. Fukuhara, T., and Matsumoto, M.: A longitudinal study of facial growth in relation to general body height during adolescence, Bull. Tokyo Med. Dent. Univ. 15: 161-170, 1968. 11. Bergersen, E. 0. : The male adolescent facial growth spurt: Its prediction and relation to skeletal maturation, Angle Orthod. 42: 319-338, 1972. 12. Singh, I., Savara, B. S., and Miller, P. A.: Interrelations of skeletal measurements of the face and body in preadolescent and adolescent girls, Growth 31: 119-131, 1967. 13. Tofani, M. I.: Mandibular growth at puberty, AM. J. ORTHOD. 62: 176-194, 1972. 14. Nanda, R. S.: The rate of growth of several facial components measured from serial cephalometric roentgenograms, AM. J. ORTHOD. 41: 658673, 1955. significance in treatment and 15. Downs, W. B.: Variations in facial relationship ; their prognosis, AX J. ORTHOD. 34: 812840, 1948. of the digestive and skeletal systems as determinants of 16. Brodie, A. G.: The interrelation tooth position, Am. J. Anat. 120: 71-77, 1967. 17. Lewis, A. B., and Roche, A. F.: Elongation of the cranial base in girls during pubescence, Angle Orthod. 42: 358-367, 1972. 18. Mitani, H.: Contributions of the posterior cranial base and mandibular condyles to facial depth and height during puberty, Angle Orthod. 43: 337-343, 1973. 19. Mitani, II.: Behaviour of the maxillary first molar in three planes with emphasis on its role of providing room for the second and third molars during growth, Angle Orthod. 45: 159-168, 1975. Process of maturation and growth 20. Sehuttleworth, F. K. : Quoted by Burstone, C. J.: prediction, AM. J. O~THOD. 49: 914, 1963. 21. Burstone, C. J.: Process of maturation and growth prediction, AM. J. ORTHOD. 49: 907919, 1963. 22. Hewitt, D., and Aeheson, R. M.: Some aspects of skeletal development through adolescence, Am. J. Phys. Anthropol. 19: 321-344, 1961. Yzls&ma
I-Chome, Bmlcyo-Ku
Mitani,
D.D.S., MS.,
D.D.k.
Tokyo, Japan
S
ince the human skull is essentially divided into two bones, i.e., the mandible and the rest of the head (craniomaxillary bone) ,I the maxillary dental arch is considered to be fixed to the cranium with the nasomaxillary complex and thus immobilized, whereas the mandible is a single bone which is the movable component in mastication. Therefore, the maxillary dentition seems to be governed by the growth of the craniomaxillary complex, while the mandibular dentition is carried in a general downward and forward direction by growth on the posterior border of the ramus and top of the condyle. Viewed in this manner, the balanced occlusion would imply that the morphogenetic pattern of each facial component and its growth and development are also so synchronized that they maintain a reasonable proportion of size and form together with a proper spatial relationship of the basal bones of the upper and lower dentitions.2 This primarily requires the synchronization of the growth of the craniomaxillary complex and mandible in rate and time of growth, sequences, and size attainment as a whole. However, facial bones and areas to which they contribute show wide ranges of variability in these matters, and the variants are not always in the same direction .3 Therefore, the lack of synchronization among them will cause a dysplastic facial pattern in all or some of the components, unless the variants compensate each other to some degree.4r h Thus, the proper occlusion of teeth would reflect the result of the dynamic as well as the static synchronization or compensation of the growth which each face confronts. However, growth of the craniomaxillary complex and the mandible with the mixtures of cartilaginous component (cranial base synchondrosis, nasal septum, and mandibular condyle) and of membranous elements, all under the control or influence of morphogenetic factors or function, is still not completely understood.6 This means that the growth of the mandible and the craniomaxillary complex could be considered to be governed by different growth mechanisms of From
76
the
Department
of
Orthodontics,
Tokyo
Medical
and
Dental
University
Pdxrtnl
Fig. 1. Tracing ployed in this
of lateral study.
changes itr occlusal and crakfacial
cephalometric
roentgenograms
showing
points
growth
and
planes
77
em-
the head skeleton, if any. These different growth mechanisms would underlie the pattern of the whole development and the spatial relationship of the dentures. Therefore, the occlusion of the teeth could help one determine whether or not the facial skeletal pattern and its growth and development have been balanced (either synchronized or compensated) as a whole in the growing process. However, the growth process in any person is continuous ; its state changes continuously over time and demonstrates distinct characteristics. Particularly at puberty, it is commonly recognized that remarkable growth takes place in the face as well as in body height and weight, and the occlusion of the permanent den& tion is mainly accomplished during this period. The present investigation was undertaken to gain further insight into the role of facial growth in establishing a proper relationship of occlusion by studying the growth changes of several facial components during puberty. Materid
Materials used in this study were composed of an B-year series of lateral cephalometric roentgenograms of thirty Japanese children (seventeen boys and thirteen girls). Each series was taken annually between the ages of 7 (6.5 to 7.7) and 15 (14.5 to 15.8) years. For two boys the films from the initial year were missing, and in another case the film from the last year was missing. The sample consisted of a random selection of skeletal patterns, the choice of material being based solely an age and on the quality of roentgenograms. However, since certain types of facial growth may be associated with a tendency toward certain kinds of malocclusion, the cases were limited to those with normal occlusion or minor Class I malocclusion. None of the subjects underwent orthodontic therapy. All materials were obtained from the files of the Department of Orthodontics, Tokyo Medical and Dental University.
78
Mitani
Am.
J. Orthod. July 1977
Method
Lat,eral cephalometric films were traced. The method of gaining measurements was based mainly on Coben’s coordinate system in which the Frankfort horizontal plane was employed as a plane of orientation. 4 Fig. 1 illustrates the points and planes used in this study and shows a diagram of the method of measurement. Measurements of craniofacial depth were taken parallel to the Frankfort plane; vertical height was measured along lines perpendicular to Frankfort. Some measurements, however, were made directly between two points to avoid the effect of angular change in length during growth when projected to the Frankfort plane. For instance, Ar-Pog could show decreased length between two different stages when measured on the Frankfort plane if its angle to FH were increased. The following measurements were used, and they were divided into two groups for the purpose of this study. Group A measurements were taken from the craniomaxillary complex, and Group B were from mandible. Group A: Ba-N, Ba-S, N-Ans, S-Ar, Ba-A, X-N Group B : ilr-Pog, Ar-Go, Go-Pog, M-L1 (Italics
indhte
direct measurement.)
A set of growth increment data constitutes a discrete time series which shows the state of a process at several points in time. The process is described by combining each point as a curve if it shows the changes in the incremental ratio. This was gained by the percentage ratio of an annual increment to the total in this study and combining each point was made by the French curves. Mean curves of the craniomaxillary group and the mandibular group were obtained individually by averaging each value at each age. Then, each curve was examined with respect to the following points : 1. Timing of occurrence of the growth spurt between two groups. 2. Ages at occurrence of the growth spurt, 3. Correlation of each process of changing rate between two groups. 4. Synchronization of timing of changing rate between two groups. The correlation coefficients between two curves were determined to examine the synchronization of each process of the changing rate. Mean curves of two groups were applied to the statistical manner of time lag correlation. Time lag correlation in this study means the method of analysis of time correlation of growth pattern between the craniomaxillary group and the mandibular group by a unit of annual lag. I8 For the examination of statistical significance of correlation coefficients, a 10 per cent level of probability was used because of the small numbers of the measurement interval. Results
Individual mean curves of growth rate of two groups are shown in Figs. 2 and 3. Distribution of age at occurrence of the maximum growth peaks is summarized in Fig. 4. The time lag correlation coefficients between two groups were obtained individually to examine the synchronization of each process of the changing rate. The results are shown in Table I. The maximum annual increment and the total increment of each component during the period studied are shown in Table II.
Pubertal
chavzges in occl~csal and craniofacial
growth
79
0 10 0
8
9
10
11
12
13
14
15
ape
10 0
7
8
9
10
Fig. 2. Male individual craniomaxillary group. mum peak rate.
11
13
12
curves Broken
of line:
14
growth Mean
-5'w rate curve
(percentage). of mandibular
Solid line: Mean group. Arrowhead:
curve of Maxi-
Discussion
The biologic environment of the dentofacial region consists of various orders, such as the morphogenetic, physiologic, functional, etc., which govern the skeletal and nonskeletal patterns of the face as well as its growth and development. The lack of balance and harmony among them will cause the dysplastic pattern on the face in all or some of the components. This has been considered as the cause
Am.
I
I
7 Fig.
8 3.
9
Female
craniomaxillary Maximum
peak
10 individual group. rate.
11
12 curves Broken
13 of line:
14
15
growth Mean
I 9
8
I
I 10
6. Orthod. July 1957
I
I
ace
11
12
13
Solid
line:
Mean
14
15 -
age
rate
(percentage).
curve
of
mandibular
group.
curve
of
Arrowhead:
of malocclusion. Since there are wide variations of facial growth in amount, timing, rate, and direction, no two faces would ever show an identical form of growth pattern. Therefore, the balanced face will include a very wide range of facial types, and variability is seen not only in racial characteristics but also within each of the racial groups and their various subdivisions.15 Furthermore, faces exhibiting malocclusion vary from those with a comparatively good skeletal balance to those with a severely unbalanced pattern. This is due to the variation of each order. In the present study, each growth curve of the craniomaxillary group and the mandibular group represented various types of peak velocity which indicate that the growth rate was accelerated and then decelerated. Among several peaks in each curve, the maximum peak was indicated by a small arrowhead in Figs. 2 and 3, and this was mostly taken to indicate the puberal growth spurt. The growth spurt in the face during puberty has been reported by many investi-
age
,lOel 00 :oO 00
female
l craniomaxillary Omandibular Fig.
4.
Table
Age
distributions
I. Time
mandibular
lag
of
occurrence
correlation
group
group
of
of
the
growth
growth
rate
between
spurt
(maximum
annual
craniomaxillary
group
increment).
and
group
Year lime
lag
-2
-1
+J
16 B 17 Total
*Significant iSignificant $Significant
-I
0
4-l
+2
Gl
G2 G3 G4 GS G6 G7 G8 G9 G 10 G 11 G 12 G 13
0.786* 0.702* 0.698* 0.701;
IO II 12 13 14 15
-2
+2
0.763t
Bl
B2 B3 B4 B5 B6 Bl B8 B9 B B B B B B B
0
0.740t 0.736t 0.749*
o&50* 0.7 lot 0.783t 0.729* 0.809t 0.9295 0.839$ 0.850t
0.8.54t
1
I
0.881$ 0.821t 8
1
0
0
I
5
2
0
at the 10 per cent level of probability. at the 5 per cent level of probability. at the 1 per cent level of probability.
gators7-14 A spurt occurred on the endocranial base (Ba-S) and the maxillary complex, as well as the mandible, of both boys and girls.17y I8 As for the timing of occurrence of the maximum peak between two groups, eleven out of seventeen boys (64.7 per cent) and seven out of thirteen girls (53.8 per cent) coincided. Therefore, on the average, approximately 60 per cent of the sample (eighteen of thirty) showed coincidence of timing of the maximum peak occurrence. This
Am.
Table
II.
Total
increment
and Total
maximum
increment
Ba-N Ba-S S-N N-Am S-AT Ba-A Ar-Pog Ar-Go Go-Pog M-L1
15.2 10.3 7.5 11.4 8.6 12.7 20.7 12.5 17.2 9.1
increment
(mm.)
Male Mean
annual
of Maximum
Female S.D.
2.8 1.8 2.2 2.1 2.0 2.8 3.6 3.6 3.2 1.7
Mean
11.7 7.5 5.5 8.7 6.4 10.3 17.4 9.6 13.3 8.0
1
each
component annual
increment
Male SD.
1.7 1.7 I .4 1.6 1.8 I.7 1.9 2.2 2.1 1.7
Mean
3.6 2.7 1.7 2.4 2.4 3.2 4.6 3.8 4.1 2.6
J. Ortkod. July 1977
(mm.) Female
( S.D.
0.8 0.8 0.7 0.4 0.5 0.8 0.8 0.9 1.1 0.7
Mean
3.4 2.3 1.6 2.6 2.3 2.6 4.3 2.8 3.6 2.0
S. D.
0.6 0.6 0.4 I.0 0.9 0.7 I.2 0.7 0.7 0.4
seems to indicate that the pubertal growth spurt will occur predominantly at the same time (year unit) in the whole face. For the age at the maximum peak occurrence, the craniomaxillary group showed ten out of seventeen boys (58.8 per cent) at the ages of 12 and 13 years and ten out of thirteen girls (76.9 per cent) at 10, 11, and 12 years (Fig. 4). The mandibular group also showed its maximum peak mostly like the craniomaxillary group; ten out of seventeen boys (58.8 per cent) at 12 and 13 years and eleven out of thirteen girls (84.4 per cent) at 10, 11, and 12 years. This seems to indicate the average ages at the pubertal growth spurt in the faces of Japanese children. The female growth spurt seems to occur 2 years earlier than the male spurt; therefore, girls tend to mature earlier than boys at puberty, although they exhibited a wider range of variation with respect to the onset of the peak velocity. However, the magnitude of the growth spurt and its total increment are considerably greater in boys than in girls (Table II) .14,‘l Time lag correlation revealed that the growth pattern of the craniomaxillary group and the mandibular group was synchronized in its changing rate in eleven out of seventeen boys (64.7 per cent) and eight out of thirteen girls (61.5 per cent). This means that approximately 63 per cent of the sample showed synchronization of the growth rate pattern between the craniomaxillary complex and the mandible. However, not all of them showed the simultaneity of timing of the changing rates. Among the samples which showed the synchronization of pattern, eight out of eleven boys (72.7 per cent) and’ five out of eight girls (62.5 per cent) showed simultaneity with the age increase. Thus, the synchronization of each process of the changing rate between the eraniomaxillary complex and the mandible appeared at the same year in approximately 43 per cent (thirteen of thirty) of the sample. In Fig. 2, Case B17 shows a typical sample of growth curves in which appeared the synchronization of each process of the changing rates with simultaneous timing per year, and Case G9 in Fig. 3 shows such synchronization but with different timing of growth changes. Although the study was done on a relatively small sample and the result was based on a 10 per cent level of probability for the statistical significance, this
Volume
Number
72
Pubertal
1
changes in occlusal and craniofacial
growth
03
may indicate a tendency of the facial growth at puberty. In other words, the growth of the maxilla and mandible is primarily correlated as a whole in its rate and timing to produce and maintain a proper basal relationship of the dentures. However, this may not always take place in every face. Rate and timing may be only one of the variants which could contribute to a part of the mechanism of compensation or synchronization of various facial components during the growth process, or it may have an independent role in the construction of a dysplastic face pattern or in occlusion. For instance, although the maxilla and mandible may attain the adequate size and be balanced by the end of adolescence, if their growth timing does not synchronize anteroposteriorly during the completion of occlusion, the occlusal relationship of the teeth may be under the influence of a’ tendency toward the Class II or Class III type of basal bone relationship. However, anteroposterior malrelationship of the upper and lower dental arches may not occur on the occlusal level if the tendency is within certain limits. This is because the differing behavior in the direction of inclination of the crown and root of a tooth seems to occur mesiodistally as well as buccolingually during growth,‘” and this behavior may compensate such tendency until the growth is over. Thus, although growth in the face is essential to produce anti maintain a proper dental relationship, it must be kept in mind that the crowns of teeth which belong to the digestive system’” may play a compensative role in the completion of a balanced occlusion. The present study did not deal with the amount and direction of growth of each component, but all samples represented neither vertical nor anteropost,erior discrepancy in occlusion. Since any variation in growth would not exist by itself but would be related to others, every combination of variants should be taken into account in each face when the resulting facial pattern is analyzed. Thercfore, in the samples which did not show a synchronization in growth rate and timing, the amount and direction would have had a chief role in compensation to produce and maintain a proper occlusal relationship in this study. This seems to indicate that the process of construction of a balanced occlusion would imply the necessity of the static (amount and direction of growth) as well as the dynamic (rate and timing of growth) synchronization or compensation of growth in the face. However, individual bones of the body may show different rates of maturation, and rates of maturation may vary from one time to the nextZ2 The statistical method in the present study revealed only a tendency toward synchronization of growth changes, but this tendency was relatively small in degree. However, over-all images of two curves of individuals seem to indicate a basic similarity of trend of growth rate between the craniomaxillary complex and the mandible, although each trend is different and unique in details. If we are to gain further insight into the growth behavior of the maxillary complex and mandible as related to the construction of a proper occlusion, a more criticsal investigation is indicated. REFERENCES
1. Coben, 2. Coben, 3. Brodie,
8. E.: Growth S. E.: Growth A. G.: Facial
concept, Angle Orthod. 31: 194-201, 1961. and Class II treatment, AM. J. ORTHOD. 52: pattern; a theme on variation, Angle Orthod.
5-26,
16:
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J. Orthod. July 1977
4. Coben, S. E.: The integration of facial variants, Aaa. J. ORTHOD. 41: 407-434, 1955. 5. Enlow, D. H., Kuroda, T., and Lewis, A. B.: The morphological and morphogenetic basis for craniofacial form and pattern, Angle Orthod. 41: 161-188, 1971. 6. Limborgh, J. V.: The role of genetic and local environmental factors in the control of postnatal craniofacial morphogenesis; Mechanism and Regulation of Craniofacial Morphogenesis, Amsterdam, 1972, Swets land Zeitlinger N. V. pp. 37-47. 7. Bushra, E.: Correlations between certain craniofacial measurement, trunk, length, and stature, Hum. Biol. 21: 246256, 1949. 8. Bambha, J. K.: Longitudinal cephalometric roentgenographic study of face and cranium in relation to body height, J. Am. Dent. Assoc. 63: 776-799, 1961. 9. Hunter, C. J.: The correlation of facial growth with body height and skeletal maturation at adolescence, Angle Orthod. 36: 44-54, 1966. 10. Fukuhara, T., and Matsumoto, M.: A longitudinal study of facial growth in relation to general body height during adolescence, Bull. Tokyo Med. Dent. Univ. 15: 161-170, 1968. 11. Bergersen, E. 0. : The male adolescent facial growth spurt: Its prediction and relation to skeletal maturation, Angle Orthod. 42: 319-338, 1972. 12. Singh, I., Savara, B. S., and Miller, P. A.: Interrelations of skeletal measurements of the face and body in preadolescent and adolescent girls, Growth 31: 119-131, 1967. 13. Tofani, M. I.: Mandibular growth at puberty, AM. J. ORTHOD. 62: 176-194, 1972. 14. Nanda, R. S.: The rate of growth of several facial components measured from serial cephalometric roentgenograms, AM. J. ORTHOD. 41: 658673, 1955. significance in treatment and 15. Downs, W. B.: Variations in facial relationship ; their prognosis, AX J. ORTHOD. 34: 812840, 1948. of the digestive and skeletal systems as determinants of 16. Brodie, A. G.: The interrelation tooth position, Am. J. Anat. 120: 71-77, 1967. 17. Lewis, A. B., and Roche, A. F.: Elongation of the cranial base in girls during pubescence, Angle Orthod. 42: 358-367, 1972. 18. Mitani, H.: Contributions of the posterior cranial base and mandibular condyles to facial depth and height during puberty, Angle Orthod. 43: 337-343, 1973. 19. Mitani, II.: Behaviour of the maxillary first molar in three planes with emphasis on its role of providing room for the second and third molars during growth, Angle Orthod. 45: 159-168, 1975. Process of maturation and growth 20. Sehuttleworth, F. K. : Quoted by Burstone, C. J.: prediction, AM. J. O~THOD. 49: 914, 1963. 21. Burstone, C. J.: Process of maturation and growth prediction, AM. J. ORTHOD. 49: 907919, 1963. 22. Hewitt, D., and Aeheson, R. M.: Some aspects of skeletal development through adolescence, Am. J. Phys. Anthropol. 19: 321-344, 1961. Yzls&ma
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