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Measurement of normal and reportedly malformed palatal vaults
162
T h e ]ournal o/ P E D I A T R I C S
Measurement of normal and reportedly malformed palatal vaults III. Down's
s y n d r o m e ( t r i s o m y 21, m o n g o l i s m )
Comparisons o[ measurements o[ palatal forms of adult~ with Down's syndrome with those o[ normal adults suggest that "'high arched" or narrow palate is not characteristic o[ the syndrome. In addition, the palates o[ affected adults appear to be appreciably smaller in all dimensions than those o[ normal adults.
Robert S. Redman, D.D.S., M.S.D., Burton L. Shapiro, D.D.S., M.S.D., and Robert J. Gorlin, D.D.S., M.S. MINNEAPOLIS, MINN.
''HIGH ARCHED PALATE '~ reportedly is a manifestation of a number of syn-
dromes? Because the reports have been based on subjective observations rather than actual measurements, it is apparent that the possibility of erroneous conclusions needs to be evaluated. Down's syndrome is a well-known entity, and its descriptive details need not be listed here. High arched palate has been listed as a typical finding in this syndrome by Warner,'-' and Levinson, Friedman, and Stamps 3 have noted that almost 75 per cent have this anomaly. The purpose of the present study is to determine if an unusuallv high or narrow From the Division o[ Oral Pathology, School o[ Dentistry, University o[ Minnesota. Supported in part by Program Grant DE 0-I770-02, United States Pubhc Health Service.
palatal arch is characteristic of Down's syndrome.
MATERIALS AND METHODS An instrument was devised to measure those dimensions of the palate which could be used to determine its arch form. A description of the instrument and a table of the measurements of normal adult palates have been published?' 4 The measurements are made to the nearest millimeter as follows (See Fig. 1) : The width of the palate is the distance between the maxillary first permanent molars at the lingual cervical lines (points A and B). The length is the distance from the peak of the interdental papilla of the permanent maxillary central incisors (point C) to a point marking the midline of the junction of the hard and soft palates (point D).
Volume 67 Number 2
Palatal vaults in Down's syndrome
A
B
Fig. 1. Dimensions of the palate used to determine its arch form.
height is the shortest distance bepoint D and the plane established by A, B, and C. index provides an indication of the of the palate relative to its width, height and is determined by the formula: width x 100. The greater the index value, the higher a n d / o r narrower is the palate.
The tween points The height
SAMPLES
Palatal measurements were taken of 48 adults with Down's syndrome at the Faribault (Minnesota) State School and Hospital. These represented virtually all of the Caucasian patients over 17 years of age at the institution who had the necessary teeth for the use of the instrument, and who also were capable of cooperating. Diagnosis of Down's syndrome was based on the subject's physical characteristics. The normal sample consisted of students at the University of Minnesota and patients at the Admissions Clinic of the University of Minnesota School of Dentistry. HYPOTHESES
In order to determine whether high arched palate is a characteristic feature of Down's syndrome, the mean palatal indices of the adults with the syndrome were compared with those of normal adults by. means of Student's t tests. The hypothesis was as follows:
16 3
There is no significant difference (i.e., p < 0.05) between the mean palatal indices of adults with Down's syndrome and normal adults of the same sex. An F test for equality of variance (p < 0.10) was used to determine the appropriate t test for each comparison? During the course of obtaining measurements of the patients with Down's syndrome, it was noted that their palates appeared to be smaller than normal. Therefore, t tests and null hypotheses similar to the above were also used to compare the mean heights, widths, and lengths of the palates. RESULTS 'Fable I presents the mean palatal dimensions and indices of the affected and normal adults, together with other descriptive statistical data. From the table it can be seen that the mean palatal indices of both males and females with Down's syndrome were higher than the mean palatal indices of normal males and females, respectively. The difference between normal and affected females was significant (0.01 < p < 0.05), but the difference between the normal and affected males was not (p > 0.40). The table also shows that all of the mean dimensions of the palates of the affected individuals were smaller than the mean dimensions of the normal individuals of the same sex. All of these differences are significant (p < 0.05) except that of the mean palatal heights for the females (0.10 < p < 0.9_0). Fig. 2 depicts the approximate frequency distribution of the palatal indices of the patients with Down's syndrome superimposed on a line showing two standard deviation limits above and below the normal mean for each sex. COMMENTS
To summarize the results, it appears that there is no difference in the relative height or width of the palates of males with Down's syndrome and of normal males, and that, though the females with the syndrome have
164
August 1965
R e d m a n , Shapiro, and Gorlin
Table I. Descriptive statistical data of palatal measurements of adults with Down's syndrome and normal adults Females Affected N -- 28; Normal N = 123 Range (ram.) Height Normal Affected
Index Normal Affected
Difference of means
Standard deviation of mean
Range (ram.)
Mean (ram.)
l
Standard deviation o[ mean
12.7 12.2 0.5
2.45 2.39
7-22 10-17
14.9 13.4 1.5
2.93 3.02
25-42 24-34
32.6 28.8 3.8
2.80 2.55
24-42 27-35
34.6 30.9 3.7
3.03 2.35
42-57 38-47
49.6 42.9 6.7
3.03 2.37
44-60 39-47
51.8 42.9 8.9
3.28 2.48
21.2-62.5 21.9-60.7
39.0 43.6 4.6
7.04 9.46
18.4-70.8 31.2-55.6
43.4 43.6 0.5
9.68 7.72
Difference of means Length Normal Affected Difference of means
Mean (ram.)
7-20 7-17
Difference of means Width Normal Affected
] 1
Males Affected N = 20; Normal N ~- 101
a somewhat higher distribution of palatal indices than the normal females, this distribution is not higher than that of the normal males. These findings suggest that a high or narrow palatal arch cannot be considered characteristic of Down's syndrome. T h e fact that the palatal dimensions of adults with the syndrome are appreciably smaller than those of normal adults perhaps explains the observations of "high arched palate." T h e observer m a y be accustomed to seeing palates of the same width and length in children which are considerably shallower. 6 It should be noted that the choice of landmarks for measuring palates used in this study m a y not detect real differences in palatal height. For example, if the hard palate slopes steeply just anterior to point D, then the measurement to that point would
be misleading. However, such a slope was not noted in the patients with Down's syndrome. SUMMARY
T h e palatal measurements of 28 female and 20 male adults with Down's syndrome were compared with those of 123 female and 101 male normal adults. T h e results suggest that the distributions of palatal indices are approximately equal a m o n g normal males, males with Down's syndrome, and females with Down's syndrome. T h e palatal index distribution of normal adult females appears to be somewhat lower than that of the other three groups. The palates of adults with Down's syndrome appear to be appreciably smaller in all dimensions than those of norreal adults. These data do not support the contention that high arched or narrow palate is a characteristic feature of Down's syndrome.
Volume 67 Number 2
Palatal vaults in Dawn's syndrome
165
MALES j
9
9
9
2E~o
+2so
43.1 MEANofNotmol Moles
FEMALES 9 I
20
9149
25
!
_L --2 SD
I
30
9 I
35
9
9149 I
40
I
45
9149149 9 I
50
9 I
55
t 99 9 J9 + 2 SD 39.0 MEANOfNormalgemales e= individualpalatal
I
60
4
6,5
index
Fig. 2. Frequency distribution of trisomy 21 palatal indices with +2 standard deviation limits of normal palatal indices. The authors express appreciation to Dr. H. H. Bruhl, Chief of Pediatrics at the Faribault, Minnesota, State School and Hospital, and to the staff of the institution. REFERENCES 1. Shapiro, B. L., Redman, R. S., and Gorlin, R. J.: Measurement of normal and reportedly malformed palatal vaults. 1. Normal adult measurements, J. D. Res. 42: 1039, 1963. 2. Warner, E. N.: A survey of mongolism, with a review of one hundred cases, Canad. M. A. J. 33: 495, 1935.
3. Levinson, A., Friedman, A., and Stamps, F.: Variability of mongolism, Pediatrics 16: 43, 1955. 4. Gorlin, R. J., and Pindborg, J. J.: Syndromes of the head and neck, New York, 1964, Blakiston Company, p. 552. 5. Walker, A. M., and Lev, J.: Statistical Inference, New York, 1953, Holt, Rinehart and Winston, pp. 154-158 and 186-187. 6. Redman, R. S., Shapiro, B. L., and Gorlin, R. J.: Measurement of normal and reportedly malformed palatal vaults. II. Normal juvenile measurements. In press.
T h e ]ournal o/ P E D I A T R I C S
Measurement of normal and reportedly malformed palatal vaults III. Down's
s y n d r o m e ( t r i s o m y 21, m o n g o l i s m )
Comparisons o[ measurements o[ palatal forms of adult~ with Down's syndrome with those o[ normal adults suggest that "'high arched" or narrow palate is not characteristic o[ the syndrome. In addition, the palates o[ affected adults appear to be appreciably smaller in all dimensions than those o[ normal adults.
Robert S. Redman, D.D.S., M.S.D., Burton L. Shapiro, D.D.S., M.S.D., and Robert J. Gorlin, D.D.S., M.S. MINNEAPOLIS, MINN.
''HIGH ARCHED PALATE '~ reportedly is a manifestation of a number of syn-
dromes? Because the reports have been based on subjective observations rather than actual measurements, it is apparent that the possibility of erroneous conclusions needs to be evaluated. Down's syndrome is a well-known entity, and its descriptive details need not be listed here. High arched palate has been listed as a typical finding in this syndrome by Warner,'-' and Levinson, Friedman, and Stamps 3 have noted that almost 75 per cent have this anomaly. The purpose of the present study is to determine if an unusuallv high or narrow From the Division o[ Oral Pathology, School o[ Dentistry, University o[ Minnesota. Supported in part by Program Grant DE 0-I770-02, United States Pubhc Health Service.
palatal arch is characteristic of Down's syndrome.
MATERIALS AND METHODS An instrument was devised to measure those dimensions of the palate which could be used to determine its arch form. A description of the instrument and a table of the measurements of normal adult palates have been published?' 4 The measurements are made to the nearest millimeter as follows (See Fig. 1) : The width of the palate is the distance between the maxillary first permanent molars at the lingual cervical lines (points A and B). The length is the distance from the peak of the interdental papilla of the permanent maxillary central incisors (point C) to a point marking the midline of the junction of the hard and soft palates (point D).
Volume 67 Number 2
Palatal vaults in Down's syndrome
A
B
Fig. 1. Dimensions of the palate used to determine its arch form.
height is the shortest distance bepoint D and the plane established by A, B, and C. index provides an indication of the of the palate relative to its width, height and is determined by the formula: width x 100. The greater the index value, the higher a n d / o r narrower is the palate.
The tween points The height
SAMPLES
Palatal measurements were taken of 48 adults with Down's syndrome at the Faribault (Minnesota) State School and Hospital. These represented virtually all of the Caucasian patients over 17 years of age at the institution who had the necessary teeth for the use of the instrument, and who also were capable of cooperating. Diagnosis of Down's syndrome was based on the subject's physical characteristics. The normal sample consisted of students at the University of Minnesota and patients at the Admissions Clinic of the University of Minnesota School of Dentistry. HYPOTHESES
In order to determine whether high arched palate is a characteristic feature of Down's syndrome, the mean palatal indices of the adults with the syndrome were compared with those of normal adults by. means of Student's t tests. The hypothesis was as follows:
16 3
There is no significant difference (i.e., p < 0.05) between the mean palatal indices of adults with Down's syndrome and normal adults of the same sex. An F test for equality of variance (p < 0.10) was used to determine the appropriate t test for each comparison? During the course of obtaining measurements of the patients with Down's syndrome, it was noted that their palates appeared to be smaller than normal. Therefore, t tests and null hypotheses similar to the above were also used to compare the mean heights, widths, and lengths of the palates. RESULTS 'Fable I presents the mean palatal dimensions and indices of the affected and normal adults, together with other descriptive statistical data. From the table it can be seen that the mean palatal indices of both males and females with Down's syndrome were higher than the mean palatal indices of normal males and females, respectively. The difference between normal and affected females was significant (0.01 < p < 0.05), but the difference between the normal and affected males was not (p > 0.40). The table also shows that all of the mean dimensions of the palates of the affected individuals were smaller than the mean dimensions of the normal individuals of the same sex. All of these differences are significant (p < 0.05) except that of the mean palatal heights for the females (0.10 < p < 0.9_0). Fig. 2 depicts the approximate frequency distribution of the palatal indices of the patients with Down's syndrome superimposed on a line showing two standard deviation limits above and below the normal mean for each sex. COMMENTS
To summarize the results, it appears that there is no difference in the relative height or width of the palates of males with Down's syndrome and of normal males, and that, though the females with the syndrome have
164
August 1965
R e d m a n , Shapiro, and Gorlin
Table I. Descriptive statistical data of palatal measurements of adults with Down's syndrome and normal adults Females Affected N -- 28; Normal N = 123 Range (ram.) Height Normal Affected
Index Normal Affected
Difference of means
Standard deviation of mean
Range (ram.)
Mean (ram.)
l
Standard deviation o[ mean
12.7 12.2 0.5
2.45 2.39
7-22 10-17
14.9 13.4 1.5
2.93 3.02
25-42 24-34
32.6 28.8 3.8
2.80 2.55
24-42 27-35
34.6 30.9 3.7
3.03 2.35
42-57 38-47
49.6 42.9 6.7
3.03 2.37
44-60 39-47
51.8 42.9 8.9
3.28 2.48
21.2-62.5 21.9-60.7
39.0 43.6 4.6
7.04 9.46
18.4-70.8 31.2-55.6
43.4 43.6 0.5
9.68 7.72
Difference of means Length Normal Affected Difference of means
Mean (ram.)
7-20 7-17
Difference of means Width Normal Affected
] 1
Males Affected N = 20; Normal N ~- 101
a somewhat higher distribution of palatal indices than the normal females, this distribution is not higher than that of the normal males. These findings suggest that a high or narrow palatal arch cannot be considered characteristic of Down's syndrome. T h e fact that the palatal dimensions of adults with the syndrome are appreciably smaller than those of normal adults perhaps explains the observations of "high arched palate." T h e observer m a y be accustomed to seeing palates of the same width and length in children which are considerably shallower. 6 It should be noted that the choice of landmarks for measuring palates used in this study m a y not detect real differences in palatal height. For example, if the hard palate slopes steeply just anterior to point D, then the measurement to that point would
be misleading. However, such a slope was not noted in the patients with Down's syndrome. SUMMARY
T h e palatal measurements of 28 female and 20 male adults with Down's syndrome were compared with those of 123 female and 101 male normal adults. T h e results suggest that the distributions of palatal indices are approximately equal a m o n g normal males, males with Down's syndrome, and females with Down's syndrome. T h e palatal index distribution of normal adult females appears to be somewhat lower than that of the other three groups. The palates of adults with Down's syndrome appear to be appreciably smaller in all dimensions than those of norreal adults. These data do not support the contention that high arched or narrow palate is a characteristic feature of Down's syndrome.
Volume 67 Number 2
Palatal vaults in Dawn's syndrome
165
MALES j
9
9
9
2E~o
+2so
43.1 MEANofNotmol Moles
FEMALES 9 I
20
9149
25
!
_L --2 SD
I
30
9 I
35
9
9149 I
40
I
45
9149149 9 I
50
9 I
55
t 99 9 J9 + 2 SD 39.0 MEANOfNormalgemales e= individualpalatal
I
60
4
6,5
index
Fig. 2. Frequency distribution of trisomy 21 palatal indices with +2 standard deviation limits of normal palatal indices. The authors express appreciation to Dr. H. H. Bruhl, Chief of Pediatrics at the Faribault, Minnesota, State School and Hospital, and to the staff of the institution. REFERENCES 1. Shapiro, B. L., Redman, R. S., and Gorlin, R. J.: Measurement of normal and reportedly malformed palatal vaults. 1. Normal adult measurements, J. D. Res. 42: 1039, 1963. 2. Warner, E. N.: A survey of mongolism, with a review of one hundred cases, Canad. M. A. J. 33: 495, 1935.
3. Levinson, A., Friedman, A., and Stamps, F.: Variability of mongolism, Pediatrics 16: 43, 1955. 4. Gorlin, R. J., and Pindborg, J. J.: Syndromes of the head and neck, New York, 1964, Blakiston Company, p. 552. 5. Walker, A. M., and Lev, J.: Statistical Inference, New York, 1953, Holt, Rinehart and Winston, pp. 154-158 and 186-187. 6. Redman, R. S., Shapiro, B. L., and Gorlin, R. J.: Measurement of normal and reportedly malformed palatal vaults. II. Normal juvenile measurements. In press.