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Anatomic measurements of human teeth extracted from males between the ages of 17 and 21 years
Anatomic measurementsof human teeth extracted from males betweenthe ages of 17 and 21 years Arne M. Bjorndal, D.D.S., M.S.,” William G. Henderson, M.P.H., Ph.D.,*’ Iowa City, Iowa, Arthur Eddy Skidmore, D.D.S., M.S.,**# Morgatitown, W. Va., and Frank H. Kellner, D.D.S.,##‘* Charleston, S. C. Experience has found older published studies describing anatomic measurements of human teeth to be unsatisfactory for present-day clinical use. This article presents new measurements made on all types of teeth extracted from Caucasian males between the ages of 17 and 21 years. These data should prove to be helpful to the practitioner for performing successful endodontic treatment.
S
ince endodontic treatment is performed today more than ever before and on all teeth in the mouth, renewed interest has developed in dental anatomy and morphology. It is important that the practitioner know how many roots, root canals, ramifications, and possible exceptions are present in each tooth. Also, knowledge of the overall length of the teeth, the mesiodistal and buccolingual crown diameters, and other measurements is critical, sometimes determining success or failure of treatment. Several investigators have reported dimensions of human teeth, but we have found none of these studies to be completely satisfactory for clinical use. G. V. Black,l in his Descriptive Anatomy of the Human. Teeth, reported measurements of all human teeth. However, he did not mention his sample sizes, nor did he define the age groups from which the teeth were secured. Miihlreiter,2 in his anatomy text, lists some of these measurements, but not all. Hess3 and others *Professor
and Head, Division
of Endodontics,
College
*‘Assistant Professor of Biostatistics, Department tistry, College of Dentistry, University of Iowa. ***Assistant Professor, Department of Endodontics, University. ****Commander,
U. S. Navy,
Charleston,
of Dentistry,
of Preventive College
University
of Iowa.
and Community
of Dentistry,
Den-
West Virginia
5. C.
791
792
Bjomdal
Oral November,
et al.
-----
Surg. 1974
--
1 I I 4 Y a %--_ -4 IAl --I I L,
’ 4 --
I 1 I
d
-- 1 - 1 I -DIP-
Fig. 1. D,, Length over all; D2, crown height; crown diameter; D,, labiolingual crown diameter.
single
root
length
; Dn, mesiodistal
Table I. Measurement key D, = length overall; D, = crown height; D, = single root length; D, = mesial root length; D, = distal root length; D, = labial root length; D, = lingual root length; D, = mesiobuccal root length; D8 = distobuccal root length; D,, = palatal root length; D,, = mesiodistal crown diameter; D,, = labiolingual crown diameter
have described the anatomy of teeth, but very little is said about dimensions. In the text by Pucci,4 figures are given which appear to be different from those of Black’s, and the calculations of average, maximum, and minimum lengths are suspect because extreme values were eliminated. Ingle5 has listed figures “modified” from Pucci. Weine’s’j method of measuring over-all length may not accurately assess actual tooth size. The purpose of this article is to fill partially this void in the dental anatomy literature by presenting certain measurements made on extracted teeth of all types from males in the age group 17 to 21 years. METHODS AND MATERIALS The material for the study consisted of teeth extracted from recruits at the United States Naval Training Center, Great Lakes, Illinois. The subjects were Caucasian males between the ages of 17 and 21 years. Anatomic measurements were made on all types of teeth except third molars. The measurements included over-all length, crown height, root length,’ mesiodistal crown diameter, and labiolingual crown diameter. Most sample sizes were large enough (greater than fifteen) to produce statistically reliable estimates of the dimensions measured. Exceptions to this were the mesiodistal *All roots were measured for multirooted
teeth.
Volume 38 Number 5
Anatomic
measurements of human teeth
793
-Dlg 1 -’1----
FQ. d. DI, Length over all; D,, crown height; crown diameter; D,, lingual root length.
D,, labial root length;
D,, labiolingual
I I 41 I 1-- L-J ----- - , 0 ’ % % 1 I em10. I
YE e
- - ‘,I
Fig. J. Dz, Crown height; D4, me&l crown diameter.
root length; 4, distal root length; D=, labiolingual
crown diameter for some teeth and all dimensions for the mandibular cuspid. All teeth were stored in jars of formalin, from which they were removed and cleaned, and were then placed in jars of distilled water prior to the taking of the measurements. The measurements of over-all length, crown height, and root length were made in a plane parallel to the long axis of the tooth. The measurements of mesiodistal and labiolingual crown diameter were made perpendicular to the long axis of the tooth. Table I defines all measurements, and Figs. 1 through 4 illustrate them. Two examiners took each measurement independently. Whenever a disagreement resulted, the measurements were repeated until the discrepancy was resolved. The following descriptive statistics were compiled for each measurement on each type of tooth :
794
Oral Surg. November, 1974
BjorndaZ et al.
i--D,,
-
Fig. 4. D,, Length over all; D,, crown height; root length; root length.
D,,, mesiodistal
crown
diameter;
D,, mesiobuccal root length ; D9, distobuccal D,?, labiolingual crown diameter; D,,, palatal
1. Mean 2. Standard deviation 3. Coefficient of variation 4. Maximum 5. Minimum 6. Range 7. Selected percentiles 8. Absolute frequency distribution 9. Per cent frequency distribution 10. Cumulative per cent frequency distribution To present all of these statistics in this paper would be prohibitive. Therefore, only statistics (1) through (6) are given for all measurements on all teeth. Selected percentiles, and the absolute, per cent, and cumulative per cent frequency distributions are presented for the overall length of the maxillar? central incisor in order to give the reader an idea of the usefulness of these statistics. The complete set of statistics is available from the authors upon request. No measurements were taken where restorations or excessive occlusal wear or caries made them inaccurate. No three-rooted maxillary first premolars or tworooted maxillary second premolars were recorded in this material. One mandibular seconci premolar with two roots was found, but was not included because of a root fracture. One mandibular cuspid had two roots. RESULTS
Table II presents the sample size (n), mean, standard deviation (X.1).), coefficient of variation (C.V.) , maximum, minimum, and range for the measurements of the maxillary teeth. Table 111 presents these same statistics for the mandibular teeth. The following brief explanation of these descriptive statistical tools may
Volume Number
38 5
Anatomic
measurements of human teeth
795
II. Measurements of maxillary teeth (mm.)
Table
LQbiodistal lingual mown m-own I diameter I diameter Mesio-
Tooth Central
Overall length
Crown height
Root length
incisor
Lean
::Dv: Max. Mill. Range Lateral incisor Gean S.D. iii& Mill.’ Range Cuspid n Mean S.D. C.V. Max. Min.
37 23.7 1.5 6.5 27.3 21.5 5.8
39
42 23.1 1.7 7.2 26.0
42
40 12.5 1.5 12.1 15.2
11.2
0.9 7.6 12.7
0.6 6.7 10.3 8.0 2.3
9.1 6.1
9.3 3.4
46 13.0 1.6 12.1 15.8
09:: 8.3 11.7
21
t3 13:5 8.2 5.0 3.2
8.1
9.8
6.8
3.6
6.0
51 11.0 1.0
53 16.3 2.0 12.3
1E
20.9
ii4
12.2 8.7
6:s 1.5
51 27.3 2.6
9.6 33.3 22.3
8:7
5.1
30
i::
41
;:
5:8 8.3 6.7 1.6 44
06.46 !i*E 6:5
2:o 51 8.4 0.6 7.0
9.6 6.9 2.7
Lingual
Labial premolar
Gean S.D. C.V. Max. Min. Range Second premolar Gean S.D. C.V. Max. Min. R,ange
33 13.7 1.5 10.8 16.1
11.5 7.8 3.7
46, 22.3 2.1
42 8.5 0.8
48 14.4
9.2
8.9 10.1
13.0
26.4 16.7
9.7
36
i3 9:3
9
36 13.7 1.5
36 22.3 1.7 7.7 25.8 18.8 7.0
7.0 0.2 3.3 7.6 6.8 0.8
11.0 17.2 10.7 6.5
10.0 6.1
1.9
7.0 3.1
Mesiobuccal First
9.0
19.2
11.0 First
20
18.9 9.7 9.2 Diatobucd
29 9.5 0.5 5.3 10.5 8.5 2.0
15 7.2 0.6 7.8 8.5 6.3 2.2
40
9 10.9
31 11.8 0.4 3.8 12.5 10.7 1.8
9.4 0.6
5.9 10.7 8.5 2.2
Palatal
molar
n Mean 8.D. C.V. Max. Min. Range Second molar n Mean E Max. Min. Range
46 22.3 1.4 6.5 25.0
19.6
37 8.4 0.6
si.9 7:3
49 12.9 1.2
9.5 15.6 10.4 5.2
48 13.1 1.5 11.7 18.0 10.4 7.6
49 14.2 1.3 9.5 17.1 11.9
1z 9.9
5.2
2.0
40 13.8
5.4
2.3
40 22.2 1.2 5.5 25.2 20.1 5.1
31 8.4 0.6 7.5
40 13.3 1.3
40 12.8
1.0
1.1
9.8
9.6
16.3 10.2
8.0 14.5
8.1 15.8
11.0
10.9 4.9
7.3 2.3
6.1
3.5
0.7
9 10.2 0.7
1!:! 8.9 2.2
28 11.8 0.7 6.1 13.2 10.5 2.7
796 Bjorndd
et al.
Oral November,
Ill. Measurements of mandibular teeth (mm.)
Table
Mesioaistal cmwn
Overall
Crown
length
height
LXi.ll
16 21.8
9
CE Ma;. Min. Range Lateral incisor
i-i 25:l 19.4 5.7
16 9.7 1.0 10.5 11.5 7.6 3.9
16 23.3 1.2 4.9 25.0 21.0 4.0
16 10.4 0.5 4.9 11.3 9.2 2.1
8 6.0 0.4
8 26.0 1.4 2G.i 24:6 2.8
8 11.6 0.8 7.0 12.2 10.1 2.1
1s:o 13.6 4.4
17 22.9 0.9 4.0 24.2 21.2 3.0
16 8.9 0.6 6.3 9.6 7.7 1.9 17 8.6 0.5
Tooth Central
Root length
I
aiamtar
Labiolingual c-i-own I diameter
incisor
Lean
E: Max. Min. Range Cuspid* n Mean E: Max. Min. Range First premolar n Mean S.D. C.V. Max. Min. Range Second premolar n Mean S.D. C.V. Max. Min. Range First
Surg. 1974
ii3 2:1 9.3 25.0 19.3 5.7
5.7 0.3 5.2 6.2 5.4 0.8
2
15 6.2 0.3 5.6 6.8 5.5 1.3
6 6.7 0.5 7.1 7.1 5.9 1.2
6 7.8 1.0 13.1 8.7 6.0 2.7
17 15.0 1.1 7.3 16.7 12.9 3.8
6 7.2 0.2 3.4
9 7.9 0.3 4.4 8.5 7.4 1.1
23 14.4 1.8 12.2 17.0 11.0 6.0
6 7.4
2
16.0 10.3 5.7 1:.7
if
iti s:o 1.7
18 5.9 0.2 3.6 6.3 5.5 0.8
E 0:7
50.54 s:o 6.9 1.1
16 8.6 0.5 6.2 9.5 7.7 1.8
Me&al
Distal
2% 19:3 5.7
46 8.3 0.7 9.0 10.2 6.4 3.8
68 15.1 1.2 8.0 17.3 11.9 5.4
61 13.6 1.2 9.0 16.1 10.9 5.2
25 11.8 0.5 4.5 12.8 11.1 1.7
19 10.8 0.7 6.1 12.4 9.4 3.0
60 21.7 1.5 6.8 25.8 19.0 6.8
49 8.7 0.9 10.8 13.1 6.8 6.3
62 13.8 1.3
63 13.4
19 11.4 0.7 6.4 13.2 10.0 3.2
38 10.3 0.4 3.9 11.5 9.5 2.0
molar
n Mean S.D. C.V. Max. Min. Range Second molar n Mean S.D. C.V. Max. Mill. Range
45 22.0 1.4
*One mandibular cuspid tooth lingual root 13.0 mm. in length.
had two
1% 10.3 7.3 root-a
2 17:o 10.3 6.7 labia.1 root
14.5 mm. in length
and z
Volume Number
38 5
Table
IV.
maxillary
Anatomic Selected percentiles central incisor
measurements of human teeth
of the distribution
of overall
lengths
797
for the
Percentiles
Tooth Maxillary
central
incisor
20th
1 dOth
( SOth
1 40th
) 50th
21.6
22.1
22.6
23.0
23.9
1 60th 1 70th 1 80th 1 90th 24.5
V. Absolute, per cent, and cumulative per cent frequency for over-all length of the maxillary central incisor
Table
Overall
length
(mm.)
Absolute
21.0 - 21.9 22.0 - 22.9 23.0 - 23.9 24.0 - 24.9 25.0 - 25.9 26.0 - 26.9 27.0 - 27.9 Total
frequewy
Per oent frequency
6 9 4 10 5 2 1 37
25.0
24.6
25.7
distributions
Czllnulative per oent freqwwy
16.2% 24.4. 10.8 27.0 13.5 E 100.0
16.2% 40.6 51.4 78.4 91.9 97.3 100.0
be helpful to the uninitiated reader. The lengths and widths of teeth, like most biologic variables, tend to cluster around a central value, a good measure of which is the arithmetic mean,* or simply the mean. The mean can be considered as the most typical or representative value of the set of observations. However, in spite of this property of central tendency, the individual teeth do display some degree of variation. The amount of variability can be estimated by either the standard deviation* or the coefficient of variation.* The standard deviation is a measure of absolute variation. The coefficient of variation is a measure of relative variation, i.e., the amount of variability of the observations (as measured by the SD) relative to their magnitude (as measured by the mean). The coefficient of variation is a unitless quantity which can be used to compare the relative variations between two or more sets of observations having different units or different means. The maximum and minimum observations are exactly *If we denote a set of n observations defined as follows:
by YU Y3 . . . . .Y., the descriptive
statistics
m Mean = p =
Standard
Coefficent
*
=
deviation
of variation
Sum of individual observations Total number of observations
(S.D.)
(C.V.)
=
=
= $&
X 100 =
Square root of the sum of squares of the deviations of the observations from their mean divided by n-l. the SD expressed as a percentage of the mean.
are
798
Bjorndal
Table
VI. Comparison
Oral Surg. November, 1974
et al.
Measurement (mm.) Overall length Mean Max. Min. Range Crown height Mean Max. Min. Range Root length Mean Max. Min. Range Mesiodistal crown diameter Mean Max. Min. Range La.biolingual crown diameter Mean Max. Min. Range
of tooth measurements from present study with those in study
Central
indsor
Laterul
incisor
Cuspid
Black
1 BEHS
BEa&
1 BKHS
Black
1 BKHS
22.5 27.0 18.0 9.0
23.7 27.3 21.5 5.8
22.0 26.0 17.0 9.0
23.1 26.0 19.2 6.8
26.5 32.0 20.0 12.0
27.3 33.3 22.3 11.0
10.0 12.0
8.8 10.5 8.0 2.5
9.9 11.7
:::
11.2 12.7 9.3 3.4
9.5 12.0 8.0 4.0
11.0 13.8 8.7 5.1
12.0 16.0 8.0 8.0
12.5 15.2 9.1 6.1
13.0 16.0 8.0 8.0
13.0 15.8
17.3 20.5 11.0 9.5
16.3 20.9 12.2 8.7
9.0 10.0 8.0 2.0
9.0 10.3
6.4 7.0 5.0 2.0
6.9 8.2 5.0 3.2
;*i
7.7 8.3 6.8 1.5
ii::
ii4
6.0 7.0 5.0 2.0
6.6 7.5 5.5 2.0
ii
6:7 1.6
38::
i::
7:o 2.0 E 7:o 2.0
what the names entail-the largest value in the set of observations and the smallest value. The range of the observations is the difference between the maximum and minimum observations. The range is also a measure of variability. However, all three quantities (maximum, minimum, and range) are dependent upon sample size: as the sample size increases, the maximum value observed tends to become larger, the minimum tends to become smaller, and the range tends to increase. Therefore, these values should be used for comparative purposes between two or more sets of data only when the sample sizes are the same or nearly the same. With these explanations in mind, the reader can use Tables II and III to find and interpret the measurements of particular interest to him and to make any desired comparisons between dimensions of the various maxillary and mandibular teeth. The distribution of the over-all length of the maxillary central incisor is described in Table IV. This table presents selected percentiles (tenth, twentieth, for the distribution of the overall length. The Xth thirtieth, . . ., ninetieth) percentile is that value of the variable such that X per cent of the observations are less than the value, and (100-X) per cent of the observations are greater than the value. Thus, for example, 50 per cent of the maxillary central incisors
8.4 9.6 6.9 2.7
Volume 38 Number 5
Anatomic
measurements of human teeth
799
by G. V. Black Maxillary First
arch
Second premolar
premolar
First molar
Second molar Black ( BKHS
Blade
) BEHS
Black
( BKHS
Black
1 BKHS
20.6 22.5 17.0 5.5
22.3 25.8 18.8 7.0
21.5 27.0 16.0 9.0
22.3 26.4 16.7 9.7
20.8 24.0 17.0 7.0
22.3 25.0 19.6 5.4
20.0 24.0 16.0 8.0
22.2 25.2 20.1 5.1
8.2 9.0 7.0 2.0
9.1 11.5 7.8 3.7
7.5 9.0 7.0 2.0
8.5 10.1 7.0 3.1
it;; 7.0 2.0
8.4 9.6 7.3 2.3
E 6:0 2.0
E 7:3 2.3
14.0 19.0 10.0 9.0
14.4 18.9 9.7 9.2
7.0 7.6 6.8 0.8
6.8 8.0 6.0 2.0
9.5
8.8 10.0 7.5 2.5
12.4 14.0 10.0 4.0 7.2 8.0 7.0 1.0 9.1 10.0 8.0 2.0
La 13.7 16.1 10.0 6.1
MD
Li
13.7 17.2 10.7 6.5 ,
10.5
8.5 2.0
DB
P
’
,MD
MB
P
13.2 12.9 13.1 14.2 16.0 15.6 18.0 17.1 10.0 10.4 10.4 5.2 , 7.6 11.9 6.0 5.2
13.0 13.3 12.8 13.8 17.0 16.3 14.5 15.8 10.2 11.0 10.9 i:: 6.1 3.5 4.9
7.2 8.5 6.3 2.2
10.7 12.0 9.0 3.0
10.9
9.2
11.9 9.9 2.0
10.0 7.0 3.0
10.2 11.1 8.9 2.2
9.4 10.7 8.5 2.2
11.8 12.0 11.0 1.0
11.8 12.5 10.7 1.8
11.5 12.5 10.0 2.5
11.8 13.2 10.5 2.7
have overall lengths less than 23.9 mm. (the 50th percentile), and 50 per cent have overall lengths greater than 23.9 mm. Table V presents the absolute, per cent, and cumulative per cent frequency distributions for the overall length of the maxillary central incisor. The per cent and cumulative per cent frequency distributions also are displayed graphically in Figs. 5 and 6. Frequency distributions are useful for relating the frequencies with which the various values of the measurement occur. The per cent frequency distribution is of greater use than the absolute frequency distribution because it enables one to compare more readily the sizes of the classes relative to the entire group. For example, it is more meaningful to say that 27.0 per cent of the maxillary central incisors have an overall length between 24.0 mm. and 24.9 mm. than it is to say that ten out of thirty-seven of them have an overall length within this range. The cumulative per cent frequency distribution accumulates the per cent frequencies of the individual classes. The line graph in Fig. 6 can be used to determine what percentage of maxillary central incisors have an overall length greater than or less than a given length. One needs only to extend a vertical
BOO Bjorndal Table
Oral Surg. November, 1974
et al.
VII. Comparison
of tooth measurements from present study with those in study Central
Measwrement (mm.) Overall length Mean Max. Min. Range Crown height Mean Max. Min. Root length Mean Max. Min. Range Mesiodistal crown diameter Mean Max. Min. Range Labiolingual crown diameter Mean Max. Min. Range
incisor
Lateral
incisor
CUspid
Bla.ok
1 BEHS
1 Blaok
1 BKHS
1 Black
1 BKHS
20.7 24.0 16.0 8.0
21.8 25.1 19.4 5.7
21.1 27.0 18.0 9.0
23.3 25.0 21.0 4.0
25.6 32.5 20.0 12.5
26.0 27.4 24.6 2.8
9.7 11.5 7.6 3.9
9.6 12.0
10.4 11.3 9.2 2.1
10.3 12.0 8.0 4.0
11.6 12.2 10.1 2.1
11.8 16.0 9.0 7.0
12.8 15.0 10.7 4.3
12.7 17.0 11.0 6.0
13.5 16.0 10.3 5.7
15.3 21.0 11.0 10.0
15.7 18.0 13.6 4.4
5.4 6.0 5.0 1.0
5.7 6.2 5.4 0.8
5.9 6.5 5.0 1.5
6.0 6.6 5.5 1.1
6.9 9.0 5.0 4.0
6.7 7.1 5.9 1.2
6.0 6.5 5.5 1.0
5.9 6.3 5.5 0.8
6.4
6.2
i:;: 1.5
t-E 1:3
7.9 10.0 6.0 4.0
7.8 8.7 6.0 2.7
line above the given length, and where it intersects the curve is the desired cumulative per cent. For example, from Fig. 6, by extending a line above the point 24.5 mm. on the horizontal axis and where it intersects the graph across to the vertical axis, it can be determined that approximately 62 per cent of maxillary central incisors have an overall length less than 24.5 mm., whereas 38 per cent of the lengths are greater than 24.5 mm. Conversely, the same graph can be used to determine the value for which X per cent of the teeth have overall lengths less than this value, and (100-X) per cent have lengths greater than the value. In this case a horizontal line is extended from the point X per cent on the vertical axis, and where it intersects the graph is the desired value for overall length. Thus, it can be seen from Fig. 6 that 50 per cent of the maxillary central incisors have an overall length less than 23.9 mm. Comparison
with
Black’s
data
The results of the present study were compared with the data published by G. V. Black in his Descriptive Anatomy of tb Human Teeth. Only the means, maximums, minimums, and ranges could be compared since these were the only descriptive statistics reported by Black. Tables VI and VII present the results of these comparisons.
Volume 38 Number 5
Anatomic
measurements of human teeth
801
by G. V. Black arch
~llXi&Ty
First
premlar
Seed
premolar
1
First
molar
Second molar
Black
1 BEHS
1 Black
1 BKHS
1 Black
1 BKHS
21.6 26.0 18.0 8.0
22.9 24.2 21.2 3.0
22.3 26.0 18.0 8.0
22.3 25.0 19.3 5.7
21.0 24.0 18.0 6.0
22.0 25.0 19.3 5.7
19.8 22.0 18.0 4.0
21.7 25.8 19.0 6.8
ri::
if:
10.0 7.9
8.6
10.0 7.7
10.2 8.3
6.9
13.1 8.7
6.5 2.5
717 1.9
6.0 4.0
i-i 1:7
7.0 3.0
6.4 3.8
E 2.0
6.8 6.3
14.0 18.0 11.0 7.0
15.0 16.7 12.9 3.8
14.4 17.5 11.5 6.0
14.4 17.0 11.0 6.0
6.9 8.0 6.0 2.0
i.:
i::,
0.7
6.5 1.5
11.2 12.0 11.0 1.0
11.8 12.8 11.1 1.7
10.7 11.0
619
7.4 8.0 6.9 1.1
1.0
11.4 13.2 10.0 3.2
ifi
8.5 7.9
9.0 8.0
9.5 8.6
11.5 10.3
12.4 10.8
10.5 10.1
11.5 10.3
::':
2'::
1:;
11.0 0.5
9.4 3.0
9.5 1.0
9.5 2.0
7:o 1.0
Y . 15.1 13.2 17.3 15.0 11.9 11.0 4.0 _ 5.4
1 Black
& 16:l 10.9 5.2
I I
1 BKES
M , 12.9 13.8 14.0 17.6 12.0 10.3 2.0 _ 7.3
10.0
D
13.4 17.0 10.3 6.7
The mean lengths and diameters from the present study are greater than those from Black’s study, with few exceptions. The differences are largest for overall length and crown height. The root lengths for multirooted teeth were difficult to compare since only one root length was presented in Black’s data, and the measured root was not specified. Although the mean values for the present study were greater than those for Black’s study, the range in values (the maximum minus the minimum) tended to be larger in Black’s data. This could have resulted from Black having had larger samples of teeth. No statistical testing could be done since Black did not specify the standard deviation or size of his samples. SUMMARY Anatomic measurements were made on all types of teeth, except third molars, extracted from Caucasian males between the ages of 17 and 21 years. The measurements included over-all length, crown height, root length, mesiodistal crown diameter, and labiolingual crown diameter. Statistics computed for each measurement on each tooth included: the mean; standard deviation; coefficient of variation ; maximum; minimum; range; selected percentiles; and absolute, per cent, and cumulative per cent frequency distributions. Because of space limitations, only the first six statistics could be presented for all teeth. A com-
802
Bjorndal
Oral Surg. November, 1974
et al.
a 25.0-
1
20.0-
LL 15.0. I o.oI
5.0.
Ovmll Length (mm) F6g. 5. Per cent frequency distribution of over-all length of the maxillary
cential incisor.
Overall Length (mm) of over-all length of the maxillary
Fig. 6. Cumulative per cent frequency distribution
central incisor.
plete set of statistics is available from the authors upon request. These measurements should be helpful to the practitioner for performing successful endodontic treatment. The data from the present study were compared to the measurements presented by G. V. Black in his Descriptive Anatomy of the HUWWYLTeeth. The mean lengths and diameters from the present study were found to be greater than those from Black’s study, with few exceptions. However, the ranges in values in Black’s study were larger than those of the present study. These differences are difficult to explain with certainty since Black failed to report his sample sizes or the population from which the teeth were obtained. REFRRCNCES
1. Black, G. V.: Descriptive Anatomy of the Human Teeth, Philadelphia, White Dental Manufacturing Co., pp. 16-21.
1902, The S. S.
Volume Number
38 5
Anatomic
measurements of human teeth
803
2. Miihlreiter, E.: Anatomy des menschlichen Gebisses, Leipzig, 1928, Publisher Arthur Felix, pp. 40, 48, 88, 112. 3. Hess, W.: Anatomy of the Root Canals of the Teeth of the Permanent Dentition, Part I, New York, 1925, Wm. Wood and Company, p. 51. 4. Pucci, F. M.: Conductos Radiculares Anatomia, Patologia Y Terapia, Vol. II, Second Part, Montevideo, 1945, Medico Quirurgica. 5. Ingle, J. I.: Endodontics., Philadelphia, 1965, Lea & Febiger, p. 180. 6. Weine, F. S.: Endodontlc Therapy, St. Louis, 1973, The C. V. Mosby Company, p. 148. Reprint reqzlests to : Dr. A. M. Bjorndal Division of Endodontics College of Dentistry University of Iowa Iowa City, Iowa 52242
S
ince endodontic treatment is performed today more than ever before and on all teeth in the mouth, renewed interest has developed in dental anatomy and morphology. It is important that the practitioner know how many roots, root canals, ramifications, and possible exceptions are present in each tooth. Also, knowledge of the overall length of the teeth, the mesiodistal and buccolingual crown diameters, and other measurements is critical, sometimes determining success or failure of treatment. Several investigators have reported dimensions of human teeth, but we have found none of these studies to be completely satisfactory for clinical use. G. V. Black,l in his Descriptive Anatomy of the Human. Teeth, reported measurements of all human teeth. However, he did not mention his sample sizes, nor did he define the age groups from which the teeth were secured. Miihlreiter,2 in his anatomy text, lists some of these measurements, but not all. Hess3 and others *Professor
and Head, Division
of Endodontics,
College
*‘Assistant Professor of Biostatistics, Department tistry, College of Dentistry, University of Iowa. ***Assistant Professor, Department of Endodontics, University. ****Commander,
U. S. Navy,
Charleston,
of Dentistry,
of Preventive College
University
of Iowa.
and Community
of Dentistry,
Den-
West Virginia
5. C.
791
792
Bjomdal
Oral November,
et al.
-----
Surg. 1974
--
1 I I 4 Y a %--_ -4 IAl --I I L,
’ 4 --
I 1 I
d
-- 1 - 1 I -DIP-
Fig. 1. D,, Length over all; D2, crown height; crown diameter; D,, labiolingual crown diameter.
single
root
length
; Dn, mesiodistal
Table I. Measurement key D, = length overall; D, = crown height; D, = single root length; D, = mesial root length; D, = distal root length; D, = labial root length; D, = lingual root length; D, = mesiobuccal root length; D8 = distobuccal root length; D,, = palatal root length; D,, = mesiodistal crown diameter; D,, = labiolingual crown diameter
have described the anatomy of teeth, but very little is said about dimensions. In the text by Pucci,4 figures are given which appear to be different from those of Black’s, and the calculations of average, maximum, and minimum lengths are suspect because extreme values were eliminated. Ingle5 has listed figures “modified” from Pucci. Weine’s’j method of measuring over-all length may not accurately assess actual tooth size. The purpose of this article is to fill partially this void in the dental anatomy literature by presenting certain measurements made on extracted teeth of all types from males in the age group 17 to 21 years. METHODS AND MATERIALS The material for the study consisted of teeth extracted from recruits at the United States Naval Training Center, Great Lakes, Illinois. The subjects were Caucasian males between the ages of 17 and 21 years. Anatomic measurements were made on all types of teeth except third molars. The measurements included over-all length, crown height, root length,’ mesiodistal crown diameter, and labiolingual crown diameter. Most sample sizes were large enough (greater than fifteen) to produce statistically reliable estimates of the dimensions measured. Exceptions to this were the mesiodistal *All roots were measured for multirooted
teeth.
Volume 38 Number 5
Anatomic
measurements of human teeth
793
-Dlg 1 -’1----
FQ. d. DI, Length over all; D,, crown height; crown diameter; D,, lingual root length.
D,, labial root length;
D,, labiolingual
I I 41 I 1-- L-J ----- - , 0 ’ % % 1 I em10. I
YE e
- - ‘,I
Fig. J. Dz, Crown height; D4, me&l crown diameter.
root length; 4, distal root length; D=, labiolingual
crown diameter for some teeth and all dimensions for the mandibular cuspid. All teeth were stored in jars of formalin, from which they were removed and cleaned, and were then placed in jars of distilled water prior to the taking of the measurements. The measurements of over-all length, crown height, and root length were made in a plane parallel to the long axis of the tooth. The measurements of mesiodistal and labiolingual crown diameter were made perpendicular to the long axis of the tooth. Table I defines all measurements, and Figs. 1 through 4 illustrate them. Two examiners took each measurement independently. Whenever a disagreement resulted, the measurements were repeated until the discrepancy was resolved. The following descriptive statistics were compiled for each measurement on each type of tooth :
794
Oral Surg. November, 1974
BjorndaZ et al.
i--D,,
-
Fig. 4. D,, Length over all; D,, crown height; root length; root length.
D,,, mesiodistal
crown
diameter;
D,, mesiobuccal root length ; D9, distobuccal D,?, labiolingual crown diameter; D,,, palatal
1. Mean 2. Standard deviation 3. Coefficient of variation 4. Maximum 5. Minimum 6. Range 7. Selected percentiles 8. Absolute frequency distribution 9. Per cent frequency distribution 10. Cumulative per cent frequency distribution To present all of these statistics in this paper would be prohibitive. Therefore, only statistics (1) through (6) are given for all measurements on all teeth. Selected percentiles, and the absolute, per cent, and cumulative per cent frequency distributions are presented for the overall length of the maxillar? central incisor in order to give the reader an idea of the usefulness of these statistics. The complete set of statistics is available from the authors upon request. No measurements were taken where restorations or excessive occlusal wear or caries made them inaccurate. No three-rooted maxillary first premolars or tworooted maxillary second premolars were recorded in this material. One mandibular seconci premolar with two roots was found, but was not included because of a root fracture. One mandibular cuspid had two roots. RESULTS
Table II presents the sample size (n), mean, standard deviation (X.1).), coefficient of variation (C.V.) , maximum, minimum, and range for the measurements of the maxillary teeth. Table 111 presents these same statistics for the mandibular teeth. The following brief explanation of these descriptive statistical tools may
Volume Number
38 5
Anatomic
measurements of human teeth
795
II. Measurements of maxillary teeth (mm.)
Table
LQbiodistal lingual mown m-own I diameter I diameter Mesio-
Tooth Central
Overall length
Crown height
Root length
incisor
Lean
::Dv: Max. Mill. Range Lateral incisor Gean S.D. iii& Mill.’ Range Cuspid n Mean S.D. C.V. Max. Min.
37 23.7 1.5 6.5 27.3 21.5 5.8
39
42 23.1 1.7 7.2 26.0
42
40 12.5 1.5 12.1 15.2
11.2
0.9 7.6 12.7
0.6 6.7 10.3 8.0 2.3
9.1 6.1
9.3 3.4
46 13.0 1.6 12.1 15.8
09:: 8.3 11.7
21
t3 13:5 8.2 5.0 3.2
8.1
9.8
6.8
3.6
6.0
51 11.0 1.0
53 16.3 2.0 12.3
1E
20.9
ii4
12.2 8.7
6:s 1.5
51 27.3 2.6
9.6 33.3 22.3
8:7
5.1
30
i::
41
;:
5:8 8.3 6.7 1.6 44
06.46 !i*E 6:5
2:o 51 8.4 0.6 7.0
9.6 6.9 2.7
Lingual
Labial premolar
Gean S.D. C.V. Max. Min. Range Second premolar Gean S.D. C.V. Max. Min. R,ange
33 13.7 1.5 10.8 16.1
11.5 7.8 3.7
46, 22.3 2.1
42 8.5 0.8
48 14.4
9.2
8.9 10.1
13.0
26.4 16.7
9.7
36
i3 9:3
9
36 13.7 1.5
36 22.3 1.7 7.7 25.8 18.8 7.0
7.0 0.2 3.3 7.6 6.8 0.8
11.0 17.2 10.7 6.5
10.0 6.1
1.9
7.0 3.1
Mesiobuccal First
9.0
19.2
11.0 First
20
18.9 9.7 9.2 Diatobucd
29 9.5 0.5 5.3 10.5 8.5 2.0
15 7.2 0.6 7.8 8.5 6.3 2.2
40
9 10.9
31 11.8 0.4 3.8 12.5 10.7 1.8
9.4 0.6
5.9 10.7 8.5 2.2
Palatal
molar
n Mean 8.D. C.V. Max. Min. Range Second molar n Mean E Max. Min. Range
46 22.3 1.4 6.5 25.0
19.6
37 8.4 0.6
si.9 7:3
49 12.9 1.2
9.5 15.6 10.4 5.2
48 13.1 1.5 11.7 18.0 10.4 7.6
49 14.2 1.3 9.5 17.1 11.9
1z 9.9
5.2
2.0
40 13.8
5.4
2.3
40 22.2 1.2 5.5 25.2 20.1 5.1
31 8.4 0.6 7.5
40 13.3 1.3
40 12.8
1.0
1.1
9.8
9.6
16.3 10.2
8.0 14.5
8.1 15.8
11.0
10.9 4.9
7.3 2.3
6.1
3.5
0.7
9 10.2 0.7
1!:! 8.9 2.2
28 11.8 0.7 6.1 13.2 10.5 2.7
796 Bjorndd
et al.
Oral November,
Ill. Measurements of mandibular teeth (mm.)
Table
Mesioaistal cmwn
Overall
Crown
length
height
LXi.ll
16 21.8
9
CE Ma;. Min. Range Lateral incisor
i-i 25:l 19.4 5.7
16 9.7 1.0 10.5 11.5 7.6 3.9
16 23.3 1.2 4.9 25.0 21.0 4.0
16 10.4 0.5 4.9 11.3 9.2 2.1
8 6.0 0.4
8 26.0 1.4 2G.i 24:6 2.8
8 11.6 0.8 7.0 12.2 10.1 2.1
1s:o 13.6 4.4
17 22.9 0.9 4.0 24.2 21.2 3.0
16 8.9 0.6 6.3 9.6 7.7 1.9 17 8.6 0.5
Tooth Central
Root length
I
aiamtar
Labiolingual c-i-own I diameter
incisor
Lean
E: Max. Min. Range Cuspid* n Mean E: Max. Min. Range First premolar n Mean S.D. C.V. Max. Min. Range Second premolar n Mean S.D. C.V. Max. Min. Range First
Surg. 1974
ii3 2:1 9.3 25.0 19.3 5.7
5.7 0.3 5.2 6.2 5.4 0.8
2
15 6.2 0.3 5.6 6.8 5.5 1.3
6 6.7 0.5 7.1 7.1 5.9 1.2
6 7.8 1.0 13.1 8.7 6.0 2.7
17 15.0 1.1 7.3 16.7 12.9 3.8
6 7.2 0.2 3.4
9 7.9 0.3 4.4 8.5 7.4 1.1
23 14.4 1.8 12.2 17.0 11.0 6.0
6 7.4
2
16.0 10.3 5.7 1:.7
if
iti s:o 1.7
18 5.9 0.2 3.6 6.3 5.5 0.8
E 0:7
50.54 s:o 6.9 1.1
16 8.6 0.5 6.2 9.5 7.7 1.8
Me&al
Distal
2% 19:3 5.7
46 8.3 0.7 9.0 10.2 6.4 3.8
68 15.1 1.2 8.0 17.3 11.9 5.4
61 13.6 1.2 9.0 16.1 10.9 5.2
25 11.8 0.5 4.5 12.8 11.1 1.7
19 10.8 0.7 6.1 12.4 9.4 3.0
60 21.7 1.5 6.8 25.8 19.0 6.8
49 8.7 0.9 10.8 13.1 6.8 6.3
62 13.8 1.3
63 13.4
19 11.4 0.7 6.4 13.2 10.0 3.2
38 10.3 0.4 3.9 11.5 9.5 2.0
molar
n Mean S.D. C.V. Max. Min. Range Second molar n Mean S.D. C.V. Max. Mill. Range
45 22.0 1.4
*One mandibular cuspid tooth lingual root 13.0 mm. in length.
had two
1% 10.3 7.3 root-a
2 17:o 10.3 6.7 labia.1 root
14.5 mm. in length
and z
Volume Number
38 5
Table
IV.
maxillary
Anatomic Selected percentiles central incisor
measurements of human teeth
of the distribution
of overall
lengths
797
for the
Percentiles
Tooth Maxillary
central
incisor
20th
1 dOth
( SOth
1 40th
) 50th
21.6
22.1
22.6
23.0
23.9
1 60th 1 70th 1 80th 1 90th 24.5
V. Absolute, per cent, and cumulative per cent frequency for over-all length of the maxillary central incisor
Table
Overall
length
(mm.)
Absolute
21.0 - 21.9 22.0 - 22.9 23.0 - 23.9 24.0 - 24.9 25.0 - 25.9 26.0 - 26.9 27.0 - 27.9 Total
frequewy
Per oent frequency
6 9 4 10 5 2 1 37
25.0
24.6
25.7
distributions
Czllnulative per oent freqwwy
16.2% 24.4. 10.8 27.0 13.5 E 100.0
16.2% 40.6 51.4 78.4 91.9 97.3 100.0
be helpful to the uninitiated reader. The lengths and widths of teeth, like most biologic variables, tend to cluster around a central value, a good measure of which is the arithmetic mean,* or simply the mean. The mean can be considered as the most typical or representative value of the set of observations. However, in spite of this property of central tendency, the individual teeth do display some degree of variation. The amount of variability can be estimated by either the standard deviation* or the coefficient of variation.* The standard deviation is a measure of absolute variation. The coefficient of variation is a measure of relative variation, i.e., the amount of variability of the observations (as measured by the SD) relative to their magnitude (as measured by the mean). The coefficient of variation is a unitless quantity which can be used to compare the relative variations between two or more sets of observations having different units or different means. The maximum and minimum observations are exactly *If we denote a set of n observations defined as follows:
by YU Y3 . . . . .Y., the descriptive
statistics
m Mean = p =
Standard
Coefficent
*
=
deviation
of variation
Sum of individual observations Total number of observations
(S.D.)
(C.V.)
=
=
= $&
X 100 =
Square root of the sum of squares of the deviations of the observations from their mean divided by n-l. the SD expressed as a percentage of the mean.
are
798
Bjorndal
Table
VI. Comparison
Oral Surg. November, 1974
et al.
Measurement (mm.) Overall length Mean Max. Min. Range Crown height Mean Max. Min. Range Root length Mean Max. Min. Range Mesiodistal crown diameter Mean Max. Min. Range La.biolingual crown diameter Mean Max. Min. Range
of tooth measurements from present study with those in study
Central
indsor
Laterul
incisor
Cuspid
Black
1 BEHS
BEa&
1 BKHS
Black
1 BKHS
22.5 27.0 18.0 9.0
23.7 27.3 21.5 5.8
22.0 26.0 17.0 9.0
23.1 26.0 19.2 6.8
26.5 32.0 20.0 12.0
27.3 33.3 22.3 11.0
10.0 12.0
8.8 10.5 8.0 2.5
9.9 11.7
:::
11.2 12.7 9.3 3.4
9.5 12.0 8.0 4.0
11.0 13.8 8.7 5.1
12.0 16.0 8.0 8.0
12.5 15.2 9.1 6.1
13.0 16.0 8.0 8.0
13.0 15.8
17.3 20.5 11.0 9.5
16.3 20.9 12.2 8.7
9.0 10.0 8.0 2.0
9.0 10.3
6.4 7.0 5.0 2.0
6.9 8.2 5.0 3.2
;*i
7.7 8.3 6.8 1.5
ii::
ii4
6.0 7.0 5.0 2.0
6.6 7.5 5.5 2.0
ii
6:7 1.6
38::
i::
7:o 2.0 E 7:o 2.0
what the names entail-the largest value in the set of observations and the smallest value. The range of the observations is the difference between the maximum and minimum observations. The range is also a measure of variability. However, all three quantities (maximum, minimum, and range) are dependent upon sample size: as the sample size increases, the maximum value observed tends to become larger, the minimum tends to become smaller, and the range tends to increase. Therefore, these values should be used for comparative purposes between two or more sets of data only when the sample sizes are the same or nearly the same. With these explanations in mind, the reader can use Tables II and III to find and interpret the measurements of particular interest to him and to make any desired comparisons between dimensions of the various maxillary and mandibular teeth. The distribution of the over-all length of the maxillary central incisor is described in Table IV. This table presents selected percentiles (tenth, twentieth, for the distribution of the overall length. The Xth thirtieth, . . ., ninetieth) percentile is that value of the variable such that X per cent of the observations are less than the value, and (100-X) per cent of the observations are greater than the value. Thus, for example, 50 per cent of the maxillary central incisors
8.4 9.6 6.9 2.7
Volume 38 Number 5
Anatomic
measurements of human teeth
799
by G. V. Black Maxillary First
arch
Second premolar
premolar
First molar
Second molar Black ( BKHS
Blade
) BEHS
Black
( BKHS
Black
1 BKHS
20.6 22.5 17.0 5.5
22.3 25.8 18.8 7.0
21.5 27.0 16.0 9.0
22.3 26.4 16.7 9.7
20.8 24.0 17.0 7.0
22.3 25.0 19.6 5.4
20.0 24.0 16.0 8.0
22.2 25.2 20.1 5.1
8.2 9.0 7.0 2.0
9.1 11.5 7.8 3.7
7.5 9.0 7.0 2.0
8.5 10.1 7.0 3.1
it;; 7.0 2.0
8.4 9.6 7.3 2.3
E 6:0 2.0
E 7:3 2.3
14.0 19.0 10.0 9.0
14.4 18.9 9.7 9.2
7.0 7.6 6.8 0.8
6.8 8.0 6.0 2.0
9.5
8.8 10.0 7.5 2.5
12.4 14.0 10.0 4.0 7.2 8.0 7.0 1.0 9.1 10.0 8.0 2.0
La 13.7 16.1 10.0 6.1
MD
Li
13.7 17.2 10.7 6.5 ,
10.5
8.5 2.0
DB
P
’
,MD
MB
P
13.2 12.9 13.1 14.2 16.0 15.6 18.0 17.1 10.0 10.4 10.4 5.2 , 7.6 11.9 6.0 5.2
13.0 13.3 12.8 13.8 17.0 16.3 14.5 15.8 10.2 11.0 10.9 i:: 6.1 3.5 4.9
7.2 8.5 6.3 2.2
10.7 12.0 9.0 3.0
10.9
9.2
11.9 9.9 2.0
10.0 7.0 3.0
10.2 11.1 8.9 2.2
9.4 10.7 8.5 2.2
11.8 12.0 11.0 1.0
11.8 12.5 10.7 1.8
11.5 12.5 10.0 2.5
11.8 13.2 10.5 2.7
have overall lengths less than 23.9 mm. (the 50th percentile), and 50 per cent have overall lengths greater than 23.9 mm. Table V presents the absolute, per cent, and cumulative per cent frequency distributions for the overall length of the maxillary central incisor. The per cent and cumulative per cent frequency distributions also are displayed graphically in Figs. 5 and 6. Frequency distributions are useful for relating the frequencies with which the various values of the measurement occur. The per cent frequency distribution is of greater use than the absolute frequency distribution because it enables one to compare more readily the sizes of the classes relative to the entire group. For example, it is more meaningful to say that 27.0 per cent of the maxillary central incisors have an overall length between 24.0 mm. and 24.9 mm. than it is to say that ten out of thirty-seven of them have an overall length within this range. The cumulative per cent frequency distribution accumulates the per cent frequencies of the individual classes. The line graph in Fig. 6 can be used to determine what percentage of maxillary central incisors have an overall length greater than or less than a given length. One needs only to extend a vertical
BOO Bjorndal Table
Oral Surg. November, 1974
et al.
VII. Comparison
of tooth measurements from present study with those in study Central
Measwrement (mm.) Overall length Mean Max. Min. Range Crown height Mean Max. Min. Root length Mean Max. Min. Range Mesiodistal crown diameter Mean Max. Min. Range Labiolingual crown diameter Mean Max. Min. Range
incisor
Lateral
incisor
CUspid
Bla.ok
1 BEHS
1 Blaok
1 BKHS
1 Black
1 BKHS
20.7 24.0 16.0 8.0
21.8 25.1 19.4 5.7
21.1 27.0 18.0 9.0
23.3 25.0 21.0 4.0
25.6 32.5 20.0 12.5
26.0 27.4 24.6 2.8
9.7 11.5 7.6 3.9
9.6 12.0
10.4 11.3 9.2 2.1
10.3 12.0 8.0 4.0
11.6 12.2 10.1 2.1
11.8 16.0 9.0 7.0
12.8 15.0 10.7 4.3
12.7 17.0 11.0 6.0
13.5 16.0 10.3 5.7
15.3 21.0 11.0 10.0
15.7 18.0 13.6 4.4
5.4 6.0 5.0 1.0
5.7 6.2 5.4 0.8
5.9 6.5 5.0 1.5
6.0 6.6 5.5 1.1
6.9 9.0 5.0 4.0
6.7 7.1 5.9 1.2
6.0 6.5 5.5 1.0
5.9 6.3 5.5 0.8
6.4
6.2
i:;: 1.5
t-E 1:3
7.9 10.0 6.0 4.0
7.8 8.7 6.0 2.7
line above the given length, and where it intersects the curve is the desired cumulative per cent. For example, from Fig. 6, by extending a line above the point 24.5 mm. on the horizontal axis and where it intersects the graph across to the vertical axis, it can be determined that approximately 62 per cent of maxillary central incisors have an overall length less than 24.5 mm., whereas 38 per cent of the lengths are greater than 24.5 mm. Conversely, the same graph can be used to determine the value for which X per cent of the teeth have overall lengths less than this value, and (100-X) per cent have lengths greater than the value. In this case a horizontal line is extended from the point X per cent on the vertical axis, and where it intersects the graph is the desired value for overall length. Thus, it can be seen from Fig. 6 that 50 per cent of the maxillary central incisors have an overall length less than 23.9 mm. Comparison
with
Black’s
data
The results of the present study were compared with the data published by G. V. Black in his Descriptive Anatomy of tb Human Teeth. Only the means, maximums, minimums, and ranges could be compared since these were the only descriptive statistics reported by Black. Tables VI and VII present the results of these comparisons.
Volume 38 Number 5
Anatomic
measurements of human teeth
801
by G. V. Black arch
~llXi&Ty
First
premlar
Seed
premolar
1
First
molar
Second molar
Black
1 BEHS
1 Black
1 BKHS
1 Black
1 BKHS
21.6 26.0 18.0 8.0
22.9 24.2 21.2 3.0
22.3 26.0 18.0 8.0
22.3 25.0 19.3 5.7
21.0 24.0 18.0 6.0
22.0 25.0 19.3 5.7
19.8 22.0 18.0 4.0
21.7 25.8 19.0 6.8
ri::
if:
10.0 7.9
8.6
10.0 7.7
10.2 8.3
6.9
13.1 8.7
6.5 2.5
717 1.9
6.0 4.0
i-i 1:7
7.0 3.0
6.4 3.8
E 2.0
6.8 6.3
14.0 18.0 11.0 7.0
15.0 16.7 12.9 3.8
14.4 17.5 11.5 6.0
14.4 17.0 11.0 6.0
6.9 8.0 6.0 2.0
i.:
i::,
0.7
6.5 1.5
11.2 12.0 11.0 1.0
11.8 12.8 11.1 1.7
10.7 11.0
619
7.4 8.0 6.9 1.1
1.0
11.4 13.2 10.0 3.2
ifi
8.5 7.9
9.0 8.0
9.5 8.6
11.5 10.3
12.4 10.8
10.5 10.1
11.5 10.3
::':
2'::
1:;
11.0 0.5
9.4 3.0
9.5 1.0
9.5 2.0
7:o 1.0
Y . 15.1 13.2 17.3 15.0 11.9 11.0 4.0 _ 5.4
1 Black
& 16:l 10.9 5.2
I I
1 BKES
M , 12.9 13.8 14.0 17.6 12.0 10.3 2.0 _ 7.3
10.0
D
13.4 17.0 10.3 6.7
The mean lengths and diameters from the present study are greater than those from Black’s study, with few exceptions. The differences are largest for overall length and crown height. The root lengths for multirooted teeth were difficult to compare since only one root length was presented in Black’s data, and the measured root was not specified. Although the mean values for the present study were greater than those for Black’s study, the range in values (the maximum minus the minimum) tended to be larger in Black’s data. This could have resulted from Black having had larger samples of teeth. No statistical testing could be done since Black did not specify the standard deviation or size of his samples. SUMMARY Anatomic measurements were made on all types of teeth, except third molars, extracted from Caucasian males between the ages of 17 and 21 years. The measurements included over-all length, crown height, root length, mesiodistal crown diameter, and labiolingual crown diameter. Statistics computed for each measurement on each tooth included: the mean; standard deviation; coefficient of variation ; maximum; minimum; range; selected percentiles; and absolute, per cent, and cumulative per cent frequency distributions. Because of space limitations, only the first six statistics could be presented for all teeth. A com-
802
Bjorndal
Oral Surg. November, 1974
et al.
a 25.0-
1
20.0-
LL 15.0. I o.oI
5.0.
Ovmll Length (mm) F6g. 5. Per cent frequency distribution of over-all length of the maxillary
cential incisor.
Overall Length (mm) of over-all length of the maxillary
Fig. 6. Cumulative per cent frequency distribution
central incisor.
plete set of statistics is available from the authors upon request. These measurements should be helpful to the practitioner for performing successful endodontic treatment. The data from the present study were compared to the measurements presented by G. V. Black in his Descriptive Anatomy of the HUWWYLTeeth. The mean lengths and diameters from the present study were found to be greater than those from Black’s study, with few exceptions. However, the ranges in values in Black’s study were larger than those of the present study. These differences are difficult to explain with certainty since Black failed to report his sample sizes or the population from which the teeth were obtained. REFRRCNCES
1. Black, G. V.: Descriptive Anatomy of the Human Teeth, Philadelphia, White Dental Manufacturing Co., pp. 16-21.
1902, The S. S.
Volume Number
38 5
Anatomic
measurements of human teeth
803
2. Miihlreiter, E.: Anatomy des menschlichen Gebisses, Leipzig, 1928, Publisher Arthur Felix, pp. 40, 48, 88, 112. 3. Hess, W.: Anatomy of the Root Canals of the Teeth of the Permanent Dentition, Part I, New York, 1925, Wm. Wood and Company, p. 51. 4. Pucci, F. M.: Conductos Radiculares Anatomia, Patologia Y Terapia, Vol. II, Second Part, Montevideo, 1945, Medico Quirurgica. 5. Ingle, J. I.: Endodontics., Philadelphia, 1965, Lea & Febiger, p. 180. 6. Weine, F. S.: Endodontlc Therapy, St. Louis, 1973, The C. V. Mosby Company, p. 148. Reprint reqzlests to : Dr. A. M. Bjorndal Division of Endodontics College of Dentistry University of Iowa Iowa City, Iowa 52242