Mesiodistal crown diameters of permanent teeth in male Ametican Negroes

Harris J. Keene, D.D.S. Houston, Terns

I nformation concerning tooth size in human populations is of great importance to clinicians in the diagnosis and treatment of malocclusions, and it is also of interest to anthropologists and other students of human biology. Although considerable odontometric data on numerous populations have been reported in the literature, there are few reports on the dentition of the American Negro. Moss and associates’ measured and compared both American Negro and Caucasian teeth, but their analysis was based on a limited sample of extracted specimens from the postcanine dentition of dental clinic patients living in the New York City area. The largest sample of American Negroes studied odontometrically was repotted by Richardson and Malhotra2 and included mesiodistal measurements on the permanent teeth of 162 males and females living in the Nashville, Tennessee, area. The sample included patients of an orthodontic practice, persons from the Meharry Medical College craniofacial growth study, and the school’s dental clinic patients.

In view of the limited geographic distribution apparent in the above mentioned reports, the present study was undertaken in an attempt to provide odontometric data on the American Negro male from a less restricted geographic area and to compare this informa- tion with existing measurements3 on a comparable group of 387 Caucasian males from the same broad geographic area.

Materials and methods

Subjects for this research were selected from the recruit population at the Naval Training Center, Great Lakes, Illinois, and consisted of fifty-six Negro males with com- pletely intact dentitions and no evidence of dental caries experience (DMFT = 0) at the time of examination. The Great Lakes Training Center receives recruits primarily from the eastern third of the United States, and many of the men come from large metropolitan areas east of the Mississippi River.4

Alginate impressions of maxillary and mandibular dental arches were taken, dental casts were made, and mesiodistal crown diameters (to the nearest 0.1 mm.) were obtained by the method of Moorrees and associates’ by means of sliding vernier calipers with sharpened points. In order to obtain an estimate of intraexaminer measurement error, duplicate measurements were taken of 280 teeth from the casts of ten persons. Means, standard deviations, and coefficients of variation (CV = SD X lOO/mean) for the

From the University of Texas Dental Branch, Dental Science Institute

0002-9416/79/070095+05$00.50/0 0 1979 The C.V. Mosby Co. 95

Table I. Mesiodistal crown diameters (mm.) of permanent teeth in m;~lc hegl-oca

and Caucasians -.-

Nc y ro ( ‘uu~~llsiwl*

i

Tooth No. Maul S.D. c. v. No. MCYUl S.D. C.V. .S~‘O)‘~‘.\

Maxilla I’ left I’ right I2 left I” right C left C right p’ left p’ right p’ left p’ right M’ left M’ right M’ left MY right

Mandible I, left I, right I, left I, right C left C right P, left P, right P, left P, tight M, left M, right M? left M, right

55 8.Y5 0.602 55 8.95 0.608 56 1.23 0.614 56 I. IS 0.928 56 8. I3 0.485 56 8.15 0.469 56 7.55 0.489 56 7.51 0.474 55 7.03 0.465 56 7.08 0.470 55 IO.‘)2 0.604 56 Il.00 0.594 54 IO.72 0.783 55 10.73 0.822

55 5.44 0.394 56 5.42 0.404 55 6.00 0.420 56 6.08 0.457 56 7.36 0.480 56 7.35 0.475 56 7.62 0.500 56 7.59 0.514 56 7.66 0.564 56 7.59 0.555 56 II.68 0.638 56 II.69 0.639 52 Il.30 0.867 53 11.2’) 0.844

6.73 385 x.4’1 0.568 6.69 5.75 6.79 387 8.50 0.577 6.79 5.56 8.49 384 6.53 0.545 8.35 8.97

12.98 384 6.51 0.544 8.36 7.71 5.Y7 384 7.71 0.412 5.34 7.37 5.75 383 7.72 0.42 I 5.45 7.41 6.48 384 6.73 0.401 5.96 14.64 6.31 384 6.65 0.409 6.15 15.04, 6.61 385 6.41 0.432 6.74 IO. I6 6.64 385 6.43 0.428 6.66 II.02 5.53 386 10.33 0.513 4.97 7.07 5.40 387 10.23 0.510 4.0’) 10.85 7.30 384 9.73 0.609 6.26 II.12 7.66 382 9.70 0.622 6.41 I I.32

7.24 385 5.22 0.371 7.11 4.23 7.45 385 5.20 0.353 6.79 4.49 6.90 387 5.81 0.400 6.88 5.00 7.52 385 5.79 0.397 6.86 5.27 6.52 387 6.77 0.392 5.79 10.73 6.46 387 6.75 0.391 5.79 Il.11 6.56 385 6.82 0.418 6. I3 13.79 6.77 385 6.80 0.430 6.32 13.17 7.36 383 6.93 0.462 6.67 Il.23 7.31 382 6.89 0.459 6.66 10.94 5.46 387 10.87 0.609 5.60 9.76 5.47 387 10.87 0.619 5.69 9.65 7.61 382 10.27 0.635 6.18 10.73 7.48 380 10.30 0.627 6.09 10.76

* Keen&’

twenty-eight-tooth dentition (third molars excluded) were obtained. The mean values obtained for the Negro sample were compared statistically with data previously reported for a group of 387 caries-free Caucasian recruits from the same population.” Between- group differences were evaluated for statistical significance by the “t” test for indepen- dent samples.‘j The ratios of the mean dimensions for specific morphologic tooth groups within each arch were also calculated for comparison with the data obtained by Richardson and Malhotra.2 The ratio was computed by Bolton’s method in which the smaller tooth of a pair is divided by the larger and expressed as a percent.

Findings

A comparison of the mean mesiodistal crown diameters of the Negro and Caucasian men (Table I) indicated a consistent, systematic, and highly significant (p < 0.001) size differential favoring larger Negro dimensions throughout the twenty-eight-tooth perma- nent dentition. The magnitude of size differences ranged from 4.2 percent for the man-

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Mesiodistal crown diameters oj’ teeth in male Negroes 97

Table II. Maxillary and mandibular molar size sequence frequency in Negro and Caucasian males

Molar size

sequence

Maxilla M” > M’ M’ YZ M’

MZ < M’

Negro males* Caucasian males 1-

No. Percent No. Percent

11 20.0 46 12.0 5 9. I 19 5.0

Mandible MS ’ MI M, = M, M, < M,

11 20.8 38 9.9

4 1.5 18 4.1

38 11.1 326 85.4 - 53 100.0 382 100.0

*Present study. t Keene.”

dibular central incisors to 12.5 percent for the maxillary first premolars. The largest absolute size differences were noted for the maxillary and mandibular second molar groups in which differences in excess of 1.0 mm. were observed. The over-all sum of the combined mean mesiodistal measurements for the twenty-eight maxillary and mandibular teeth in the Negro sample (235.26 mm.) was 8.4 percent greater than for the Caucasian teeth (216.96 mm.). In the measurement error analysis where duplicate measurements of 280 teeth from the casts of ten persons were made, a mean difference of 0.05 mm. was obtained and the standard deviation of the differences was 0.138 mm.

A high degree of right-left bilateral symmetry was evident for the Negro mean values of corresponding teeth on opposite sides of the midline; intrapair differences fell within +0.05 mm. for eleven of fourteen tooth groups, and in no instance did they exceed 0.1 mm. Crown size variability as expressed by the CV was found to be least for the maxillary and mandibular first molars (5.5 percent) and greatest for the maxillary lateral incisors (average, 10.7 percent), with the remaining tooth groups falling into a range between 5.8 and 7.7 percent. Greater size variability (CV) of the more distal tooth of each morphologic class was evident in eleven of twelve possible pairings, indicating that, within sets of molars, premolars, or incisors, the distal member of the pair tended to have greater size variability than the mesial member. This was especially apparent in the maxillary incisor pairings in which CV for the lateral incisor was almost 60 percent greater than for the central incisor.

A comparison of maxillary and mandibular molar size sequence frequencies on the right side of the arch for Negroes and Caucasians is given in Table II. The most frequent sequence for both arches and both samples was the M, < M, pattern, ranging from 70.9 to 85.4 percent. The Mz > M, size sequence in the maxillary and mandibular arches of the Negroes was 20.0 percent and 20.8 percent, respectively, compared to 12.0 percent and 9.9 percent in the Caucasian sample. When the molar size sequence frequencies for the two samples were tested for lack of homogeneity by chi-square analysis, the increased proportion of the M, > M, size sequence in the Negro arches was statistically significant (p = 0.05) only for the mandible.

The ratios for the mesial and distal members of each morphologic tooth class on the

Table III. Mesiodistal crown diameter ratios for the mcsial and distal teeth of different

morphologic classes in the maxilla and mandible

Morphologic class

Incisors Maxillary Mandibular

Premolar3 Maxillary Mandibular

Molars Maxillary Mandibular

xrgr-0 lnales * Nqro mdr Y -1 (‘~rucasiurl mu/c.\ $

(p~went) (p~‘?Wl/) (pelnw)

70.9 7Y 76.6 89. I YO 8Y.8

94.3 Y4 Y6.7 100.0 94 98.7

97.5 97 94.8 Y6.6 98 Y4.8

*Present study. +Richardson and Malhotra.” $ Keene.”

right side of the maxilla and mandible are given in Table III. The calculations are in excellent agreement with the data presented by Richardson and Malhotra* with the single exception of the mandibular premolar ratio, which is considerably higher in the present study. When a comparison of the ratios obtained in the two Negro samples is made with the Caucasian data,3 Negro-to-Negro concordance and Negro-to-Caucasian discordance are considerably more apparent in the maxilla than in the mandible.

Discussion

Comparative studies in which both Negro and Caucasian dentitions have been mea- sured by the same investigator or team of investigators are relatively rare in the dental literature. When tooth dimensions from different studies by different examiners have been compared, the magnitude of interexaminer measurement error is usually unknown and minor intergroup differences can fall well within the range of experimental error.’ In the present study, mean intraexaminer error was estimated from a series of duplicate mea- surements and found to be of a low order of magnitude (0.05 mm.).

The dimensions of the caries-free male Negro teeth in this study were found to be consistently larger throughout the dentition than comparable measurements previously reported.” for a group of caries-free male Caucasians from the same population. The over-all difference for the combined sum of the measurements for twenty-eight teeth was 8.4 percent, and the size difference for individual teeth ranged between 4.2 and 12.5 percent. Lavelleg excluded the second molars in his analysis of male and female Negroes and Caucasians living in the Birmingham, England area and reported differences ranging from 4.5 percent to 20.4 percent for the male mesiodistal dimensions. The Negro teeth measured by Lavelle were larger than Caucasian teeth for every morphologic class, and the combined difference was 8.7 percent, which agrees well with the 8.4 percent calcu- lated in the present study. Although the mean measurements for individual teeth reported by Lavelle were systematically larger than those reported in the present study (Negro-ten out of twelve; Caucasian-eight out of twelve), the magnitude of the Negro-Caucasian tooth size differences (with the exception of the maxillary lateral incisor) was remarkably similar in the two studies (Table IV).

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Mesiodistal crown diameters of teeth in male Negroes 99

Table IV. Magnitude of the Negro-Caucasian size differences in mean mesiodistal crown diameter expressed as percent*

Maxillaq Present teeth study

I’ 5.4 I’ 10.3 C 5.5 P’ 12.6 P2 9.9 M’ 6.6 M* 10.4

LaveNes

6.1 20.4 10.5 13.7 10.2 6.8 t

Mandibular Present teeth Study

1, 4.2 12 4.9 C 8.8 PI 11.6 P2 10.4 Ml 7.5 M2 9.8

Lavelle9

4.5 6.3 6.9 9.7

10.7 5.0 t

*Negro tooth size larger in every comparison t Not measured.

The mean tooth measurements obtained by Richardson and Malhotra2 on male Ne- groes living in the Nashville, Tennessee, area are systematically larger than those obtained in the present study (fourteen out of fourteen tooth groups). Nevertheless, the degree of correlation was excellent (r, 0.999; p < O.OOl), and the magnitude of the differences tended to be small (range, 0.01 to 0.23 mm.). In twelve out of fourteen comparisons, the difference was less than 0.20 mm.

Summary and conclusions

The mesiodistal crown diameters were measured in a group of fifty-six male American Negroes from the recruit population at the Great Lakes Naval Training Center and com- pared with previously reported data on Caucasians from the same population. The results indicate that tooth size is consistently larger in the Negro sample, averaging about 8.4 percent for the over-all maxillary and mandibular dentition, excluding third molars.

REFERENCES 1. Moss, M. L., Chase, P. S., and Flower, R. I.: Comparative odontometry of the permanent post-canine

dentition of American whites and Negroes, Am. J. Phys. Anthropol. 27: 125- 142, 1967. 2. Richardson, E. R., and Malhotra, S. K.: Mesiodistal crown dimension of the permanent dentition of

American Negroes, AM. J. ORTHOD. 68: 157-164, 1975.

3. Keene, H. J.: Epidemiologic study of tooth size variability in caries free naval recruits, J. Dent. Res. 50: 1331-1345, 1971.

4. Keene, H. J., and Catalanotto, F. A.: Impact of fluoridated water on the caries experience of naval recruits, J. Public Health Dent. 34: 66-73, 1974.

5. Moorrees, C. F. A., Thomsen, S. O., Jensen, E., and Yen, P. K.: Mesiodistal crown diameters of the deciduous and permanent teeth in individuals, J. Dent. Res. 36: 39-47, 1957.

6. Snedecor, G. W., and Cochran, W. G.: Statistical methods, ed. 6, Ames, 1967, Iowa State University Press. 7. Bolton, W. A.: The clinical application of a tooth size analysis, AM. J. ORTHOD. 48: 504-529, 1962. 8. Hunter, W. S., and Priest, W. R.: Errors and discrepancies in measurement of tooth size, J. Dent. Res. 39:

405-414, 1960. 9. Lavelle, C. L. B.: Maxillary and mandibular tooth size in different racial groups and in different occlusal

categories, AM. J. ORTHOD. 61: 29-37, 1972. 10. Garn, S. M., Lewis, A. B., and Walenga, A. J.: Maximum confidence vaiues for the human mesiodistal

crown dimension of human teeth, Arch. Oral Biol. 13: 841-844, 1968.