Age estimation based on tooth development: a test of reliability and validity
VERA STAAF', HAKAN
MORNSTAD'
AND ULF WELANDER'
'Department of Oral Radiology and 'Department of Cariology University of Umea, Umea, Sweden
Staaf V, Mornstad H, Welander U; Age estimation based on tooth development; a test of reliability and vahdity. ScandJ Dent Res 1991; 99; 281-6. Abstract - The precision and accuracy of three commonly used methods for age determination by teeth were studied in 541 children aged 5.5-14.5 yr. These methods rely on estimation of tooth development as seen in radiographs compared with compiled dental charts. It was found that charts made from Scandinavian populations gave a rather good precision, while one from a Canadian population gave a consistent overestimate. Dependent on the method used, sex, and age, the 95% confidence interval for an individual prediction could be more than + 2 yr. Key words; age determination by teeth; forensic odontology; mineralization, teeth; panoramic radiography; permanent dentition; tooth calcification. H4kan Mornstad, Department of Forensic Odontology, Karolinska institutet, P.O. Box 4064, S-141 04 Huddinge, Sweden. Accepted for publication 28 November 1990.
Immigration of children from developing to industrialized countries is steadily increasing, and the need for accurate birth data has put pre.ssLtre on the medieal and dental professions to find as precise a method as possible for determination of the physiologic age in eases where birth data are lacking or doubted. Evaluation of the dental development has usually played an important part in the process of age determination of children with unknown birth data. The dental maturity has often been considered a good indicator of chronologic age and has been regarded as superior to other methods for evaluation of an individual's somatic maturity, such as
methods based on the development of the hand skeleton (1). The methods employed for age determination in Scandinavia have usually been those designed by HAAVIKKO (2, 3), LiLiEQ,tiisT & LUNDBERG (4), and DEMIRJIAN et al. (5, 6).
All these methods are based on the comparison of tooth development, as seen in radiographs, with standard charts compiled from a large number of individuals in a well-defined geographic region. The precision of these methods has generally been considered high, with an uncertainty of only about 2-3 months (7, 8), in spite of the rather large dispersion around an estimated age given by the original authors. DEMIRJIAN et al. (5) thus
282
STAFF ET AL.
gave a range of up to 3 yr between the 3rd and 97th percentile. HAAVIKKO (2) reported an average of + 2.3 yr between the 10th and 90th percentile. In a newly published article (9), the accuracy of some of these methods (4, 5) for age estimation was evaluated and it was concluded that the 95% confidence interval could be up to 2 yr. This newly expressed uncertainty of age determination when using tooth development as a single factor has caused us to test three of the original and most commonly used methods on a rather large and homogeneous material in order to find out with what certainty an age determination can be made when applying these methods. In order to examine the intraindividual reliability, part of the material was studied twice and the results were then compared. Material and methods
AGE DISTRIBUTION (270 BOYS, 271 GIRLS)
120
10 8
The age of the child at the time of examination was calculated in days. From the orthopantomographs the degrees of development ofthe 16 mandibular teeth were determined according to three original methods: DEMIRJIAN et al. (5), modified by DEMIRJIAN & GOLDSTEIN (6), HAAVIKKO (2),
Orthopantomographs of 541 children (270 boys and 271 girls), aged 5.5-14.5 yr (Fig. 1) were collected from the Public Dental Service in the county of Norrbotten, Sweden. This area is demographically rather homogeneous and con.sists mainly of people from the northern parts of Swe-
6
den and Finland. There is some influence of Lappish origin, but this group does not differ ethnically from Scandinavians as regards dental development. Most of the radiographs were exposed by two experienced radiographers using the same panoramic machine (Orthopantomograph 3) over a 3-yr-period at the Public Dental Service in Kiruna. A few supplementary radiographs were obtained from other clinics. Most ofthe material was eollected during a period when orthopantomographs were employed for the tracing of cases with a need of orthodontic treatment at the age of 8-9 yr. Children with lower and higher ages are more sparsely represented due to infrequent clinical indications for radiographic examinations at these ages. Cases with general diseases which could be expected to affect tooth development, and cases with missing teeth or blurred radiographic images were excluded.
14 12
AGE (YEARS)
Fig. 1. Age distribution of material (270 boys and 271 girls) pooled into 1-yr-groups.
and LiLiEQ^uiST & LUNDBERG (4).
DEMIRJIAN// al. (5, 6) identified and described eight stages of mineralization for each tooth and gave each one a score. The sum of the scores for an individual provides an estimate of dental maturity. This sum, measuring from 1 to 100, is then converted to an age between 3 and 16 yr. Since all calculations in our study were automatized, the tables in their first paper (5) were used, with the adjustments given in the updated report (6). HAAVIKKO (2) identified 12 radiographic stages of tooth formation, six of them relating to the crown and six of them to the root. For each tooth and developmental stage, a median age and its dispersion is given. In the original study, the corresponding ages for all permanent teeth present were summed and divided with the number of teeth, giving a mean age. In a later modification (3), a set of only four teeth were used. One set of teeth was used for individuals below 10 yr of age and another for individuals above this age. LiLiEQ^uisT & LUNDBERG (4) did not publish their tables, but these are available in later papers and textbooks (8, 10). For each tooth, the dental development is scored as one of seven developmental stages. The sum of the scores is then entered
283
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AGE DETERMINATION METHOD: Liliequist & Lundberg (1970)
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and in the second test 8.20 yr. There was no significant difference between the two tests {t= -0.48, P = 0.632, ?z = 37), but there was a significant correlation (r = 0.932, P
VERA STAAF', HAKAN
MORNSTAD'
AND ULF WELANDER'
'Department of Oral Radiology and 'Department of Cariology University of Umea, Umea, Sweden
Staaf V, Mornstad H, Welander U; Age estimation based on tooth development; a test of reliability and vahdity. ScandJ Dent Res 1991; 99; 281-6. Abstract - The precision and accuracy of three commonly used methods for age determination by teeth were studied in 541 children aged 5.5-14.5 yr. These methods rely on estimation of tooth development as seen in radiographs compared with compiled dental charts. It was found that charts made from Scandinavian populations gave a rather good precision, while one from a Canadian population gave a consistent overestimate. Dependent on the method used, sex, and age, the 95% confidence interval for an individual prediction could be more than + 2 yr. Key words; age determination by teeth; forensic odontology; mineralization, teeth; panoramic radiography; permanent dentition; tooth calcification. H4kan Mornstad, Department of Forensic Odontology, Karolinska institutet, P.O. Box 4064, S-141 04 Huddinge, Sweden. Accepted for publication 28 November 1990.
Immigration of children from developing to industrialized countries is steadily increasing, and the need for accurate birth data has put pre.ssLtre on the medieal and dental professions to find as precise a method as possible for determination of the physiologic age in eases where birth data are lacking or doubted. Evaluation of the dental development has usually played an important part in the process of age determination of children with unknown birth data. The dental maturity has often been considered a good indicator of chronologic age and has been regarded as superior to other methods for evaluation of an individual's somatic maturity, such as
methods based on the development of the hand skeleton (1). The methods employed for age determination in Scandinavia have usually been those designed by HAAVIKKO (2, 3), LiLiEQ,tiisT & LUNDBERG (4), and DEMIRJIAN et al. (5, 6).
All these methods are based on the comparison of tooth development, as seen in radiographs, with standard charts compiled from a large number of individuals in a well-defined geographic region. The precision of these methods has generally been considered high, with an uncertainty of only about 2-3 months (7, 8), in spite of the rather large dispersion around an estimated age given by the original authors. DEMIRJIAN et al. (5) thus
282
STAFF ET AL.
gave a range of up to 3 yr between the 3rd and 97th percentile. HAAVIKKO (2) reported an average of + 2.3 yr between the 10th and 90th percentile. In a newly published article (9), the accuracy of some of these methods (4, 5) for age estimation was evaluated and it was concluded that the 95% confidence interval could be up to 2 yr. This newly expressed uncertainty of age determination when using tooth development as a single factor has caused us to test three of the original and most commonly used methods on a rather large and homogeneous material in order to find out with what certainty an age determination can be made when applying these methods. In order to examine the intraindividual reliability, part of the material was studied twice and the results were then compared. Material and methods
AGE DISTRIBUTION (270 BOYS, 271 GIRLS)
120
10 8
The age of the child at the time of examination was calculated in days. From the orthopantomographs the degrees of development ofthe 16 mandibular teeth were determined according to three original methods: DEMIRJIAN et al. (5), modified by DEMIRJIAN & GOLDSTEIN (6), HAAVIKKO (2),
Orthopantomographs of 541 children (270 boys and 271 girls), aged 5.5-14.5 yr (Fig. 1) were collected from the Public Dental Service in the county of Norrbotten, Sweden. This area is demographically rather homogeneous and con.sists mainly of people from the northern parts of Swe-
6
den and Finland. There is some influence of Lappish origin, but this group does not differ ethnically from Scandinavians as regards dental development. Most of the radiographs were exposed by two experienced radiographers using the same panoramic machine (Orthopantomograph 3) over a 3-yr-period at the Public Dental Service in Kiruna. A few supplementary radiographs were obtained from other clinics. Most ofthe material was eollected during a period when orthopantomographs were employed for the tracing of cases with a need of orthodontic treatment at the age of 8-9 yr. Children with lower and higher ages are more sparsely represented due to infrequent clinical indications for radiographic examinations at these ages. Cases with general diseases which could be expected to affect tooth development, and cases with missing teeth or blurred radiographic images were excluded.
14 12
AGE (YEARS)
Fig. 1. Age distribution of material (270 boys and 271 girls) pooled into 1-yr-groups.
and LiLiEQ^uiST & LUNDBERG (4).
DEMIRJIAN// al. (5, 6) identified and described eight stages of mineralization for each tooth and gave each one a score. The sum of the scores for an individual provides an estimate of dental maturity. This sum, measuring from 1 to 100, is then converted to an age between 3 and 16 yr. Since all calculations in our study were automatized, the tables in their first paper (5) were used, with the adjustments given in the updated report (6). HAAVIKKO (2) identified 12 radiographic stages of tooth formation, six of them relating to the crown and six of them to the root. For each tooth and developmental stage, a median age and its dispersion is given. In the original study, the corresponding ages for all permanent teeth present were summed and divided with the number of teeth, giving a mean age. In a later modification (3), a set of only four teeth were used. One set of teeth was used for individuals below 10 yr of age and another for individuals above this age. LiLiEQ^uisT & LUNDBERG (4) did not publish their tables, but these are available in later papers and textbooks (8, 10). For each tooth, the dental development is scored as one of seven developmental stages. The sum of the scores is then entered
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into a table, where the corresponding age can be read. Duplicate readings were made for 37 randomly selected cases, and the calculated ages were compared. The scores read from the radiographs were directly entered into a microcomputer, and the calculations and statistical treatments were made with the aid ofthe SPSS/PC-h statistical package (12). The variables included were: identification number of the individual, sex, age in days, and the score for each tooth according to each of the three methods, giving a total of 51 variables. The following parameters were calculated: true age in years with one decimal place, assessed age with each of the three methods, and finally the difference between true age and the age assessed with each one of the methods. Calculations for boys and girls were kept separate since girls are generally several months earlier in their development of teeth (13).
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AGE DETERMINATION METHOD: Liliequist & Lundberg (1970)
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Fig. 4. Differences between true and assessed age with methods devised by LILIEQUIST & LUNDBERG (4).
and in the second test 8.20 yr. There was no significant difference between the two tests {t= -0.48, P = 0.632, ?z = 37), but there was a significant correlation (r = 0.932, P
