Comparative study of mesiodistal crown diameters and arch dimensions between indigenous British and Pakistani immigrant populations.код для вставкиСкачать
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 72:479-483 (1987) Comparative Study of Mesiodistal Crown Diameters and Arch Dimensions Between Indigenous British and Pakistani Immigrant Populations D. RADNZIC Orthodonic Department, University of Lee& Dental Hospital, Leeds, England KEY WORDS Arch width, Arch length, Arch perimeter ABSTRACT Over the last two decades, the United Kingdom has seen a n increase in the number of immigrants from the Indian subcontinent, mainly Pakistan. The amount of information that is available regarding parameters such as mesiodistal crown diameters and dental arch dimensions is, however, somewhat limited for this population. An investigation was carried out to compare corresponding mesiodistal crown diameters and arch dimensions between samples of the indigenous British population in Leeds (England) and the Pakistani immigrant population living in Rochdale (England). Measurements were taken from dental casts. The results showed that there were no significant differences between the two ethnic groups in corresponding mesiodistal crown diameters or arch dimensions. Data are provided for the Pakistani immigrant population in Britain. Differences in mesiodistal crown diameters and dental arch dimensions between the major ethnic groups (Australoid, Caucasoid, Mongoloid, and Negroid) have been extensively studied (Moorrees, 1957; Barrett et al. 1963, 1965; Moss et al. 1967; Barrett and Brown, 1968; Lavelle, 1970, 1972a, b; Grewe, 1970; Lavelle et al., 1970, 1971; Doran and Freedman, 1973; Mack, 1981). These investigators have shown that there are differences in corresponding mesiodistal crown diameters and arch dimensions between the various ethnic groups (as measured on dental casts), but they are of a variable nature and are often smaller than the differences between the sexes in any one population. Subgroups, of course, exist within these major ethnic groups, but these do not appear to have been investigated as extensively. Although much data are available for certain ethnic groups such as Australian Aborigines and Anglo-American Caucasians, less are available for ethnic groups from the Indian subcontinent, and none was available for Pakistani immigrants living in Great Britain. A large number of Pakistani immigrants have settled in the United Kingdom over the previous two decades, principally in the mill (c) 1987 ALAN R. LISS, INC. towns of the north. In view of this, it was felt that a n investigation was necessary to provide information about some aspects of crown sizes and dental arch dimensions in the Pakistani immigrant population as a n addition to the literature on comparative odontology. MATERIALS AND METHODS A total of 60 pairs of dental casts taken from indigenous British males in Leeds and 60 pairs of casts taken from Pakistani immigrant males living in Rochdale were measured. Ages ranged from 13 years to 15 years 11 months. The samples were chosen at random from a larger sample in each group that had met the selection criteria. Ethnic origins were determined from school records, clinical (medical) records, and from records used in previous epidemiological studies. The investigation was limited to male children of the aforementioned age range for no other rea- Received August 4, 1986; revision accrpted Octoher 22. I986 This study w as carried out in partial fulfilment of t h e requirements for t h e degree of M.D.Sc while working in t h e Orthodontic Department of t h e Uiiiversity of' Leeds Dental Ilospital. England. 480 n. RADNZIC son than availability. The selection criteria were a s follows: 1. All permanent teeth were present in each arch (excluding second and third molars) and in a sufficient state of eruption to permit measurement of the mesiodistal crown diameter. 2. There was no previous orthodontic treatment involving the permanent dentition in either arch. 3. There were no large coronal restorations that might have altered both coronal shape and size. 4. Dental casts were undamaged in areas of measurement. For each pair of casts, the following parameters were recorded in each arch: 1.Mesiodistal crown diameters 2. Arch widths 3. Arch length 4.Arch perimeter. The measurements were repeated for each cast, with a minimum period of 1 week between repeated measurements. The method of making the measurements will now be described. Mesiodistal crown diameter The greatest distance between interproxima1 contact points was measured for individual teeth in each arch, up to and including the first permanent molars. Measurements were made using a vernier gauge (Homer, West Germany) to the nearest 0.1 mm, with the blades of the caliper held perpendicular to the long axis of the crown (Howe et al., 1983) and parallel to its occlusal and vestibular surfaces. Arch widths Two dimensions of arch width were used: 1.Interincisal width, that is, the maximum distance between distal surfaces of lateral incisors 2. Mean intermolar width as calculated from values obtained for buccal and lingual intermolar widths. Both buccal and lingual intermolar dimensions were measured from the point of intersection of the gingival margin with a n extension gingivally of the buccal and lin- Fig. 1. Points of measurement of arch widths. gual fissures of the first permanent molars. Measurements were made using a vernier caliper (Homer, West Germany) to the nearest 0.1 mm. (Fig. 1). Arch length The measurement of arch length was accomplished on each cast using a n engineering depth gauge (Moore and Wright, Sheffield, England), rounding up or down to the nearest millimeter. For the present study, arch length was defined as the length of a perpendicular line from the contact point between the permanent central incisors to a line joining the distal surfaces of the first permanent molars (Fig. 2). Incidentally, the point of intersection of these two lines was found to be within a range of 2 mm either side of the midline in all the dental casts used in the study. Arch perimeter This was calculated using a modification of the formula suggested by Mills and Hamilton (1965): arch perimeter where x = = J 2 y” -t :4 arch length, but substituting: Y = mean intermolar width 2 481 CROWN AND ARCH SIZES IN BRITISH VERSUS PAKISTANIS crowns rather than their buccal extremities (Radnzic, 1985).It was felt that this method was more rapid and capable of giving more reproducible results than direct measurements on the casts. In order to minimize random and systematic errors, all measurements were performed by a single observer, as suggested by Hunter and Priest (1960).All casts were then remeasured, in a random order, with an intervening period of a t least a week in order to eliminate any possibility of memory bias. Random and systematic intraobserver errors were studied as part of a larger investigation (Radnzic, 19851, but were not found to be statistically significant (at P < 0.01). Fig. 2. Arch length measurement, RESULTS Mean values for individual mesiodistal crown diameters, arch widths, arch lengths, and arch perimeters together with variances instead of: were recorded for maxillary and mandibular arches in both ethnic groups. Student’s ‘Y’ buccal intermolar width Y = tests were carried out in order to compare 2 the sample means in each group. The results for maxillary arches are presented in Table a s suggested by Mills and Hamilton. 1and for mandibular arches in Table 2. No statistically significant differences beThis gives a value for arch perimeter as tween the groups were observed (at P < 0.01) the length of a line passing through the buc- in corresponding mesiodistal crown diamecolingual centers and incisal edges of the ters or arch dimensions. TABLE 1. Comparison of m e a n values between the two ethnic population sarnples-maxillary dental arches ( N = 60) Parameter Indigenous group Mean Variance (mm) estimate I m m i g a n t group Mean Variance (mm) estimate “t” value* Crown s u e ti? 15 Li t3 12 II I_] zi !XI 4-1 ZI !u Arch length Intermolar arch width Interincisal arch width Arch perimeter 10.69 6.91 7.09 8.04 6.87 8.97 8.98 6.86 8.12 7.13 6.96 10.70 39.07 45.26 0.39 0.21 0.14 0.18 0.31 0.31 0.30 0.37 0.18 0.16 0.21 0.34 12.06 14.19 10.65 6.92 7.24 8.10 7.07 8.86 8.86 7.05 8.12 7.27 6.95 10.63 39.62 44.78 0.37 0.21 0.27 0.20 0.29 0.26 0.29 0.31 0.20 0.29 0.18 0.35 14.51 8.07 0.346 NS’ 0.130 NS 1.897 N S 0.679 NS 2.012 NS 1.163 NS 1.197 NS 1.806 N S 0.038 NS 1.607 NS 0.148 NS 0.717 NS 0.826 NS 0.796 NS 27.55 7.14 28.24 7.13 1.417 N S 105.10 44.67 105.08 49.94 1.354 NS ”Level of significance: P < 0.01 INS. not significant. 482 D. RADNZIC TABLE 2. Comparison of mean values between the two ethnic population samples--mandibular dentul urches (N = 60) Parameter Indigenous group Mean Variance --___ (mm) estimate .. Immigrant group Mean Variance (mm) estimate “t” value* Crown size 6 6 R B Iz ri il 3 3l zl 3-l a Arch length Intermolar arch width Interincisal arch width Arch perimeter 11.23 7.35 7.32 7.25 6.15 5.56 5.53 6.12 7.21 7.31 7.35 11.24 33.75 43.82 0.47 0.19 0.16 0.16 0.13 0.12 0.10 0.11 0.13 0.15 0.18 0.45 7.17 9.04 11.12 7.36 7.34 7.19 6.11 5.55 5.57 6.12 7.18 7.28 7.43 11.08 33.57 43.18 0.30 0.15 0.29 0.25 0.14 0.10 0.11 0.11 0.22 0.23 0.19 0.31 6.89 5.81 1.029 NS’ 0.145 NS 0.209 NS 0.666 NS 0.636 NS 0.147 NS 0.572 NS 0.033 NS 0.471 NS 0.361 NS 1.016 NS 1.415 NS 0.378 NS 1.280 NS 21.64 3.92 21.31 2.44 1.014 NS 95.58 31.47 94.12 25.77 1.501 NS *Level of sipificance: P < 0 01 INS, not significant. DISCUSSION The mean values obtained for the indigenous British population sample were in agreement with other workers (Lavelle, 1970, 1972a,b; Lavelle et al., 1970, 1971; Mack, 1981).There were no previous data available for the Pakistani immigrant population living in the United Kingdom; therefore, it can only be assumed, until proven otherwise, that the present findings are representative of Pakistani male children in Britain. The results showed no statistically significant differences in corresponding mesiodistal crown diameters or arch dimensions between the Asian and non-Asian groups. This was not entirely unexpected, as the indigenous British and Pakistanis are essentially of the same ethnic root stock. Also, one cannot entirely discount the possibility of influences such as racial interbreeding and environmental factors such as diet (Moore et al. 1968) in accounting for the similarities, although there was no direct evidence for this in the present study. Racial interbreeding is unlikely among the Pakistanis in view of the strict customary attitudes towards mixed marriages. There is, however, a greater likelihood of racial intermixing in the indigenous British population due to changing attitudes and the advent of the multicultural society. Regarding diet, there is no firm evidence to suggest that the dietary backgrounds of the two samples studied were in any way different. One may argue that if any Pakistani immigrants used in the sample had come from the poorer rural areas of Pakistan, then they might have existed on coarser, more abrasive diets, which would consequently have led to greater dental attrition, particularly affecting the occlusal and interproximal surfaces of the teeth and leading to a reduction in their mesiodistal crown diameters. The results of the present investigation do not support this, although it is a situation that is frequently seen in human skulls imported from the Indian subcontinent for use by medical students. Incidentally, no significant differences were observed in either ethnic group in tooth sizes between left and right sides of the dental arches. These findings accord with those of Lavelle and Plant (1969) but not with Ballard (1944). ACKNOWLEDGMENTS I am most grateful to Mr. J.F. Gravely, senior lecturer in Orthodontics, University of Leeds Dental Hospital, for his advice and CROWN AND ARCH SIZES IN BRITISH VERSUS PAKISTANIS guidance during the investigation, and also to Mr. A.J. Doyle, district dental officer, Rochdale District Health Authority, for provision of materials and facilities. LITERATURE CITED Ballard, ML (1944) Asymmetry in tooth size: A factor in the etiology, diagnosis and treatment of malocclusion. Angle Orthod. 14:67-70. 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