A study of dental development in a Caucasian population compared with a non-Caucasian population.
AIM: The aim of the present investigation was to compare dental
development in children from a non-Caucasian population (Saudi Arabia)
with age- and gender- matched children from a Caucasian population
(Australia). STUDY DESIGN: Randomised study comparing two population
groups using a common set of standards. METHODS: Dental ages of 842
Australian and 456 Saudi Arabian children were assessed from
orthopantomograms (OPGs) using the method of Demirjian and co-workers.
The children were divided into male and female groups of 5-6, 7-8, 9-10,
11-12, and 13-14 year-olds, and the dental age of each child compared to
that the corresponding calendar age group. RESULTS: In both Australian
and Saudi Arabian children, the dental ages were higher than the
corresponding calendar ages. The largest difference between calendar and
dental ages (1.10 [+ or -] 0.80 years, p<0.001) was noted in 11-12
year-old Saudi Arabian girls, and the smallest difference (0.33 [+ or -]
1.19 years, p<0.01) in 11-12 year-old Australian boys. These
discrepancies between calendar and dental ages were significantly
different between Australian and Saudi Arabian children (p<0.01).
CONCLUSIONS: Although the results suggest that dental development of
both Caucasian and non-Caucasian children are generally underestimated
by current standards, a few age-specific differences between the two
types of population can be discerned.
Key words: dental development, dental growth, dental maturity, Caucasian children
|Publication:||Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2011 European Academy of Paediatric Dentistry ISSN: 1818-6300|
|Issue:||Date: Feb, 2011 Source Volume: 12 Source Issue: 1|
|Topic:||Event Code: 310 Science & research|
|Product:||Product Code: E121920 Children|
|Geographic:||Geographic Scope: Australia Geographic Code: 8AUST Australia|
As development of the teeth is an aspect of physical development, the assessment of dental age has relevance for diagnosis and management of growth conditions in children. It also has significant applications in clinical and forensic paediatric dentistry as well as in orthodontics [Sierra, 1987; Chaillet et al., 2004]. Although examining the number of erupted teeth may crudely assess dental maturity, the timing of emergence of the permanent teeth is not likely to be useful for prediction of biological ages and long-term treatment planning, as it is crude and inaccurate. Other methods of assessing biological and skeletal maturity such as evaluating growth changes in the small bones of the hand usually involve more invasive techniques such as exposure to general skeletal radiographs [Coutinho et al., 1993]. Current methods for the evaluation of dental age generally employ radiographic assessment of developmental ages of the teeth in comparison with the corresponding chronological or calendar ages of the subjects. This method was pioneered by Demirjian and co-workers [Demirjian et al., 1973; Demirjian and Goldstein, 1976], and uses standards based on the radiographic presentations of the stages of formation of the permanent teeth [Moorrees et al., 1963].
Although the validity and reliability of Demirjian's method has been confirmed by several studies [Farah et al., 1999; Frucht et al., 2000; Eid et al., 2002; Chaillet et al., 2004; De Salvia et al., 2004; Chaillet et al., 2005; Behbehani et al., 2006; Al-Emran 2008; Bagherpour et al., 2010; Chen et al,. 2010] some investigations have found that Demirjian's standards, which are based on a relatively small French-Canadian sample, are not applicable to non-Caucasian groups due to racial and other differences [Liversidge et al., 1999; Rozylo-Kalinowska et al., 2008]. Demirjian et al.  had recognised that the centiles for dental maturity at given ages is dependent on the population studied.
Although data is available on isolated samples of children from various parts of the world in separate publications, there have been no previous studies comparing the dental development of non-Caucasian and Caucasian children using primary data in a single analysis. Therefore, the present study aims to compare the dental development of a non-Caucasian population (Saudi Arabian) and Caucasian population (Australian) at various ages to determine differences in dental maturity of these population groups using the standards of Demirjian and co-workers .
Materials and methods
Ethical approval and permission for the study was obtained from the relevant institutions and directors of the clinical facilities involved. Orthopantomograms (OPGs) of children aged 5-14 years, which were exposed for screening and orthodontic purposes were employed for study. The OPGs of Caucasian Australian children were selected from a large health service district in the State of Queensland in Australia. The race of each subject was obtained from the parental/ guardian self-declaration of race in the routine consent forms that are required for treatment of children at the government school-based clinic. OPGs of Saudi Arabian children were similarly selected from the paediatric and orthodontic clinics at the Dental School at King Abdulaziz University, Jeddah, Saudi Arabia.
Medical and dental records of each subject were checked and children with chronic medical conditions were excluded from the study. In addition, children with hypodontia [Kan et al., 2010] and unusual dental conditions involving several teeth e.g. amelogenesis imperfecta [Seow, 1995] and pre-term births [Seow, 1996] were also excluded, as these conditions have been associated with altered rates of dental development. All OPGs of children meeting the selection criteria were included until the required number of subjects was obtained.
Assessment of dental development. The assessment of dental development from the radiographs was performed by one of the authors (AAT) and research assistant (AA--in Acknowledgement). The OPGs were viewed on a standard radiographic light-box without magnification. The technique of evaluation of dental development was based on the original method described by Demirjian and co-workers ). The method involved assessing the developmental stage of seven permanent teeth on the left side of the mandible, namely, the first and second molars, first and second premolars, canines and central and lateral incisors. An eight-grade stageing system was used to denote the particular stage of development of each tooth as observed on the radiograph. From the tables of standards provided, a numerical score for each stage of development for the particular tooth was given. The scores for the seven teeth were summed for each subject, and the dental age computed from the total score by reference to standard tables [Demirjian et al., 1973].
Data processing. The data were entered into standard spreadsheets. The children were divided into age groups of 5.0-6.9, 7.00-8.9, 9.0-10.9, 11.0-12.9, 13.0-14.9 years of age. The computed dental ages were compared with the respective calendar ages and differences were noted for each subject. The mean dental age [+ or -] S.D. for each age and gender group was computed for both Australian and Saudi Arabian populations respectively, and the differences noted. For each subject, the difference in dental and chronological ages demonstrated either matching of the ages or an acceleration or retardation of dental age relative to calendar age.
Determination of inter- and intra- examiner consistency. To determine intra-examiner and inter-examiner consistency, the examiners each evaluated 13 OPGs on two separate occasions and compared the scores given for each tooth appearance on the OPG [Levesque and Demirjian, 1980; Reventlid et al., 1996]. The kappa statistic [Landis and Koch, 1977] was used to determine intra- and inter- examiner consistency.
Statistical analysis. ANOVA and student's t-tests were employed for statistical analysis of data, using an alpha value of 0.05.
The reproducibility of the assessments was very good. The intra- and inter-examiner consistency tests for assessment of dental ages revealed agreement of 0.95 for both examiners and within the examiners.
As shown in Table 1, there were a total of 1,307 children in the study (842 Australian and 465 Saudi Arabian children). In most of the age groups, there were approximately similar proportions of males and females except for Saudi children in the age groups 13-14 years and 9-10 years where there were a predominance of girls (Table 1).
The chronological and the dental ages of Australian and Saudi Arabian male children are illustrated in Fig 1. As shown in this figure, in both Australian and Saudi Arabian boys, at all calendar ages (CA), the corresponding mean dental ages (DA) were generally higher compared with the standards of Demirjian and co-workers. In the case of male children, Australian boys in the 5-6 year-old age group showed the greatest mean difference of 0.96 [+ or -] 0.61 years (p<0.001) between their calendar and dental ages (CA-DA) whereas the 11-12 year-old age group showed the least difference of 0.33 [+ or -] 1.19 years) (p<0.01). The Australian males in age groups 7-8 years, 9-10 years and 13-14 years of age showed mean differences between calendar and dental ages (CADA) which were 0.51 [+ or -] 0.74 years (p<0.001), 0.47 [+ or -] 1.02 years (p<0.01) and 0.77 [+ or -] 1.26 years (p<0.001) respectively. ANOVA analysis revealed that among the whole sample of Australian males, the mean difference between the groups aged 11-12 years and 13-14 years was statistically significant (p<0.05).
Saudi Arabian male children, as shown in Fig. 1 on the other hand, showed the greatest increase in mean dental age compared with their calendar ages in the 3-14 year-old age group (0.87 [+ or -] 0.75 years) (p<0.05). Correspondingly the comparative data was 0.80 [+ or -] 0.97 years (p<0.01) in the 11-12 year-old age group; 0.57 [+ or -] 0.88 years (p<0.01) in the 9-10 year-old age group; 0.59 [+ or -] 0.57 years (p<0.001) in the 7-8 year-old group and 0.72 [+ or -] 0.38 years (p<0.001) in the 5-6 year-old age group. As shown in Fig. 1 all the calendar ages differed significantly from the respective dental ages within each age group (the p-values for each group are shown). However, the differences were not significantly different among the whole sample of Saudi Arabian boys.
In the case of female children, as shown in Fig. 2, Australian girls in 5-6 year-old group showed the greatest mean difference between calendar and dental ages (CA-DA) of 0.94 [+ or -] 0.71 years (p<0.001) whereas the 7-8 year-old age group showed the least (0.51 [+ or -] 0.67 years). Australian females in age groups 9-10 years, 11-12 years and 13-14 years showed mean dental ages which were 0.76 [+ or -] 1.16 years (p<0.001), 1.03 [+ or -] 1.16 years (p<0.001), 0.80 [+ or -] 1.23 years (p<0.001) greater than their respective chronological ages. ANOVA analysis also revealed that among the whole sample of Australian females, the mean difference in (CA-DA) between the 7-8 year-old and 11-12 year-old age groups was statistically significant (p<0.05).
Figure 2 also shows the data for Saudi Arabian girls that demonstrated that the greatest difference in mean dental age compared with their calendar ages (CA-DA) in the 11-12 year-old group (1.10 [+ or -] 0.80 years) (p<0.001) by comparison with 0.47 [+ or -] 0.72 years (p<0.05) in the 13-14 year-old group. Correspondingly the data was 0.71 [+ or -] 0.92 years (p<0.001) in the 9-10 year-old group, 0.63 [+ or -] 0.64 years (p<0.001) in the 7-8 year-olds and 0.77 [+ or -] 0.55 years (p<0.001) in the 5-6 year-old group. However, considering these age groups in the Saudi Arabian female sample, the differences were not statistically significant.
The differences of Australian (CA-DA) and Saudi Arabian (CADA) values for comparison are shown in Fig. 3. As depicted in the figure, Australian boys in the 5-6 year-old group had more advanced dental ages compared with similarly-aged Saudi Arabian counterparts. In contrast, in all other age groups from 7 to 14 years of age, Australian boys had higher dental ages compared with their respective calendar age groups. On the other hand, the differences between Australian and Saudi Arabian female children showed a different pattern (Fig. 3). At the age groups of 5-6 years, 9-10 years and 13-14 years, Australian female children had more advanced dental ages compared with Saudi Arabian girls. However, at the age groups of 7-8 years and 11-12 years, Australian girls had lower dental ages compared with similarly aged Saudi Arabian female children. These differences are statistically significant (p<0.01).
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
The assessment of dental ages of two population groups by the same investigators has the advantage of reducing assessor error. Furthermore, the use of the same set of standards provide a common platform to analyse data from both populations simultaneously so that direct comparison can be made regardless of whether the standards are applicable for the populations tested. Thus, this method was applied in the present study to facilitate the detailed comparison of two racial groups that do not have established dental developmental standards for the respective populations.
Although a comparison of dental maturity among various population groups is possible using meta analysis of data from previous studies, such reports are likely to show mainly general trends and not reveal detailed differences between groups. To the best of the authors' knowledge, this is the first study to compare the dental development of two population groups directly in one analysis. The present results thus demonstrate that while Australian Caucasian and Saudi Arabian children share a general trend of showing advanced dental ages, compared with those of French-Canadian children, on which the current standards were based, interesting differences could be detected between male and female children. At the age groups of 7-8 years and 11-12 years, Australian girls had lower dental ages compared with similarly aged Saudi Arabian girls. In contrast, Australian boys in the 5-6 year-old group had more advanced dental ages compared to similarly-aged Saudi Arabian boys.
The present results also extend a previous study [Al-Emran, 2008] which examined Saudi Arabian children aged from 8.5 years to 17 years of age, and reported that in that study boys were 0.3 years and girls 0.4 years ahead of French-Canadian children used in the standards. Thus, although this study showed similar trends, the present investigation demonstrated much larger mean increases in dental ages of 0.71 years for Saudi Arabian boys and 0.74 years for Saudi Arabian girls. In addition, the present results also provided the first dental values for Saudi Arabian children in the age group 5-6 years that are not available in the previous study. However, another study of children from Kuwait, a neighbouring country, had reported contrasting results of delayed mean dental ages of approximately 0.69 years using similar standards [Qudeimat and Behbehani, 2009].
Two previous studies allow comparison with the Australian children in the present investigation. The first investigation reported similar results to the present Australian children in that the standards of Demirjian et al.,  underestimated the dental ages of Western Australian children and that the mean difference of chronological and dental ages ranged between 0.02 and 1.47 years for girls and 0.08 and 1.38 years for boys [Farah et al., 1999]. The second Australian study also reported underestimation of dental ages of approximately 0.46 years for males and 0.71 years for females aged below 15 years [McKenna et al., 2002]. The differences between calendar and dental ages in both previous studies were thus within the ranges observed in Australian children in the present investigation.
Dental development is likely to be primarily influenced by hereditary factors such as race and gender, although epigenetic and environmental conditions such as nutrition may also be important [Liversidge et al., 1999; Eid et al., 2002]. Sexual dimorphism in dental development is well recognised, although there is some disagreement among the studies. A few investigators reported boys having more accelerated dental ages compared with girls although some studies have suggested the opposite [Nystrom et al., 2001; Krailassiri et al., 2002]. In addition, the original standards for dental development of Demirjian and co-workers  have been usefully employed to study dental development in many cohorts of children who with medical syndromes [Seow, 1995; Seow and Hertzberg, 1995; Seow et al., 1995]. However, the standards have been criticised for their lack of applicability to many groups due to racial differences, as well as contemporary population groups due to secular and other differences. These criticisms are based on reports from more recent studies on Western populations that have generally found accelerated dental development in contemporary cohorts of children compared with the original standards.
While Australian and Saudi Arabian children generally show advanced dental ages using the standards of Demirjian et al.,  in the age groups of 7-8 years and 11-12 years, Australian girls had relatively delayed dental ages compared to similarly aged Saudi Arabian girls. In contrast, male Australian 5-6 year-olds had more advanced dental ages compared to their Saudi peers. These results suggest that ethnic specific standards for Caucasian and non-Caucasian children are required for the assessment of dental development.
The authors thank Dr Ari Amaratunge, honorary research assistant, University of Queensland, for her assistance with the dental age assessments.
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A. Al-Tuwirqi *, T. Holcombe **, W.K. Seow *
* Centre for Paediatric Dentistry, School of Dentistry, The University of Queensland, ** Logan-Beaudesert Division, Metro South Health Service District, Queensland Health; Brisbane, Queensland, Australia.
Postal address: Dr. W.K. Seow. Centre for Paediatric Dentistry, School of Dentistry, The University of Queensland, 200 Turbot Street, Brisbane 4000, Brisbane, Australia.
Table 1. Demography of the subjects in a study of dental development in a Caucasian population compared to a non-Caucasian population. Australian Saudi Total Children Arabian Children Girls n (%) 431 (51%) 276 (59%) 707 (54%) Boys n (%) 411 (49%) 189 (41%) 600 (46%) Total n (%) 842 (100%) 465 (100%) 1307 (100%) Mean Age (5-6 years) Girls n (%) 19 (44%) 56 (54%) 75 (51%) Boys n (%) 24 (56%) 48 (46%) 72 (49%) Total n (%) 43 (100%) 104 (100%) 147 (100%) Mean Age (7-8 years) Girls n (%) 54 (45%) 77 (58%) 131 (52%) Boys n (%) 65 (55%) 56 (42%) 121 (48%) Total n (%) 119 (100%) 133 (100%) 252 (100%) Mean Age (9-10 years) Girls n (%) 119 (52%) 82 (62%) 201 (56%) Boys n (%) 110 (48%) 50 (38%) 160 (44%) Total n (%) 229 (100%) 132 (100%) 361 (100%) Mean Age (11-12 years) Girls n (%) 138 (52% ) 34 (54%) 172 (53%) Boys n (%) 125 (48%) 29 (46%) 154 (47%)
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