Forensic Sci Med Pathol (2015) 11:339–344 DOI 10.1007/s12024-015-9688-2
ORIGINAL ARTICLE
The radiographic visibility of the root pulp of the third lower molar as an age marker Daniel Pe´rez-Mongiovi1 • Alexandra Teixeira2 • Ineˆs Morais Caldas3,4
Accepted: 10 June 2015 / Published online: 24 June 2015 Springer Science+Business Media New York 2015
Abstract Purpose The aim of this work was to determine the usefulness of the visibility of the dental pulp in lower third molars in forensic age estimation. Methods Dental pulp visibility on lower third molars was assessed using a sample of 487 orthopantomograms. Intra and inter-observer agreement was determined using the Cohen’s kappa test. A descriptive analysis of the stages according to age was done. The relationship between age and stage attainment was assessed using Chi square test and the strength and direction of the linear relationship between pulp visualization stage and chronological age was evaluated using Spearman rank order correlation (rho). Equations for predicting an age above 21 years were developed using logistic regression. The level of significance was defined at p \ 0.05. Results The relationship between age and stage attainment had statistical significance for both sexes (p \ 0.001). There was a medium positive correlation between the two variables for both genders (Spearman q = 0.420, p \ 0.001 and Spearman q = 0.454, p \ 0.001, for males
& Ineˆs Morais Caldas [email protected] 1
Department of Sciences, Advanced Institute of Health Sciences-North (ISCS-N), CESPU, CRL, Rua Central de Gandra, 13174585-116 Gandra PRD, Portugal
2
Private Practice, Porto, Portugal
3
Faculty of Dental Medicine of the University of Porto, Faculdade de Medicina Denta´ria da Universidade do Porto, Rua Dr. Manuel Pereira da Silva, 4200-393 Porto, Portugal
4
CENCIFOR - Center of Forensic Sciences, Associac¸a˜o Centro de Cieˆncias Forenses, Largo da Se´ Nova, INML IP, 3000-213 Coimbra, Portugal
and females respectively). The model built for age estimation successfully predicted age over 21 in 96.2 % of the females and in 96.9 % of the males. However, only 19.6 and 27.0 % of predictions were accurate for the group that was younger than 21, for females and males, respectively. Conclusions The accuracy of predictions for the group younger than 21 years of age was low, meaning that this methodology may not be suitable for age estimation. Still, stage 3 alone proved to be a suitable age marker for determining an age over 21 years. Keywords Forensic sciences Forensic odontology Age estimation Third molar Pulp visibility
Introduction Currently, mainly due to problems arising from globalization, forensic age estimation has become increasingly important. In fact, the increasing number of non-national subjects with doubtful information regarding their birth date makes forensic age estimation necessary in several contexts, namely in the course of criminal, civil, or asylum proceedings [1–7]. Meanwhile, the Study Group on Forensic Age Diagnostics (Arbeitsgemeinschaft fu¨r Forensische Altersdiagnostik, AGFAD) has proposed guidelines for forensic age estimation. These consist of: (a) a clinic examination, performing anthropometric measures and assessment of sexual maturity signs; (b) an X-ray examination of the left hand; (c) a dental evaluation with a clinical examination and analysis of an orthopantogram (OPT); and (d) an X-ray examination or CT scan of the clavicles when hand skeletal development is completed [4, 6–10]. The information that is needed often relates to the probability of an individual being older than 14, 16, 18, or
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340
21 years old [4, 11, 12]; the third molars may be the only teeth that can be used to provide valuable information since they have not finished their developmental processes at these ages. However, the mineralization process may be completed before age 21 [13, 14] or even before age 18 [11, 15, 16]. In the Portuguese population, a previous study has showed that stage H of the eight-grade Demirjian scheme was found to be a useful marker for diagnosing an age equal to or older than 18 years, in both males and females [12], but for determining an age equal to or older than 21 years this methodology showed no usefulness, as most teeth have already completed their root development by the age of 18 years. Recently several new dental techniques have been proposed to estimate age in these cases. For instance, Olze et al. [3] referred to the use of the periodontal ligament in the lower third molars as potential age estimation criterion after completed formation of the root. We have already tested this methodology in a previous study [17] and found that there was a statistically significant relationship between age and stage of periodontal ligament development for both sexes. Furthermore, the results indicated that stage 3 of periodontal ligament visibility (i.e., when the periodontal ligament is invisible along almost the full length of two roots) could be used to state that a male is over 21 years-old; however, in females, the technique was not as accurate, and we have concluded that another marker should be used for this purpose in females. Olze et al. [18] described another methodology for forensic age estimation, using the radiographic visibility of the root pulp in the lower third molars. According to the authors, this methodology can be useful for determining both an age over 18 years as well as an age over 21-years. Thus, similarly to what we have done previously with the visibility of the periodontal ligament, the aim of this work is to assess the radiographic visibility of the root pulp in third molars, using OPT from a Portuguese population, in order to determine the suitability of this methodology in forensic age assessment, especially for determining an age over 21 years.
Materials and methods A total of 487 OPTs from Portuguese subjects aged from 17 to 30 years was assessed; 228 belonged to females, and 259 to males; subjects were divided into two groups: group a: age below 21 years; group b: age equal to or older than 21 years. Subjects attended the residency dental clinic of the Faculty of Dental Medicine of University of Porto. OPTs were taken from each subject for diagnostic purposes, and their date of birth was recorded but not revealed to the examiners. The socioeconomic background of the sample population we studied can be described as middle
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to low and the general health status of the study population was good, with no known systemic pathologies. The population affinity of the study subjects could not be verified, however all subjects had Portuguese last names and it was assumed they were born and lived in Portugal (other authors have previously adopted the procedure of assuming ethnicity based on last name, in similar circumstances [3, 11, 19]). All OPTs with unclear images, or presenting impacted third lower molars, or with incomplete root formation, carious lesions or endodontic treatment were excluded. Third molars with a single root were excluded, as the four stages could not be applied. Age and sex distribution of the material can be observed in Table 1. The visibility of the root pulp of lower third molars with completed root formation (including apical closure) was recorded, as defined by Olze et al. [18] in the following four stages (Fig. 1): • • •
•
Stage 0: The root pulp is visible along the full length of all roots; Stage 1: The root pulp is invisible in one root from apex to more than half root; Stage 2: The root pulp is invisible along almost the full length of one root or along part of the root in two roots or both; Stage 3: The root pulp is invisible along almost the full length of two roots.
The root pulp visibility was assessed in the left lower third molar (38) and, when this tooth presented any of the exclusion criteria referred, the right lower third molar (48) was used. Table 1 Age and sex distribution of the sample population Age
Females n (%)
Males n (%)
17.0–17.9
4 (1.75)
0
18.0–18.9
6 (2.63)
14 (5.41)
19.0–19.9
13 (5.70)
26 (10.04)
20.0–20.9 21.0–21.9
23 (10.09) 22 (9.65)
23 (8.89) 30 (11.58)
22.0–22.9
27 (11.84)
17 (6.56)
23.0–23.9
22 (9.65)
18 (6.95)
24.0–24.9
17 (7.46)
23 (8.89)
25.0–25.9
21 (9.21)
21 (8.11)
26.0–26.9
22 (9.65)
17 (6.56)
27.0–27.9
14 (6.14)
22 (8.49)
28.0–28.9
12 (5.26)
19 (7.34)
29.0–29.9
14 (6.14)
11 (4.25)
30.0–30.9
11 (4.82)
18 (6.95)
Total
228
259
Forensic Sci Med Pathol (2015) 11:339–344
341
Fig. 1 Schematic drawings and pictures of stages of radiographic visibility of the root pulp in lower molars (adapted from [18])
To assess reliability, 30 randomly selected OPTs were examined by two authors (DPM and AT), and 30 randomly selected OPTs were assessed twice by the first author, with a 1 month interval between the two observations. Intra and inter-observer agreement was determined using the Cohen’s kappa test. A descriptive analysis of the stages of visualization of the root pulp according to age was done. The relationship between age and stage attainment was assessed using a Chi square test and the strength and direction of the linear relationship between pulp visualization stage and chronological age was evaluated using Spearman rank order correlation (rho). Equations for predicting an age over 21 were developed using logistic regression. The level of significance was defined at p \ 0.05. Microsoft Excel (Microsoft Corp., Redmond, WA, USA) was used for data registration and IBM SPSS Statistics 22 (SPSS Inc., Chicago, IL, USA) was used for statistical analyses. This study was submitted and approved by the Ethical Board of the Faculty of Dental Medicine of University of Porto.
Results Repeated scoring of 30 radiographs revealed good agreement in both cases (k [ 0.80), indicating that there was high reproducibility and repeatability. Stage 0 first appeared at 18.2 and 17.0 years, for males and females respectively. Stage 1 was first attained at 18.4 years for males, and 17.4 years for females. Stage 2 was achieved first at 18.8 years for females and 18.1 years in males. The earliest appearance of stage 3 happened at
age 19.1 years for males and 21.2 years for females (Table 2). The relationship between age and stage attainment had statistical significance for both sexes (p \ 0.001). Stage 3 was only attained by females older than 21 years of age and by 91.7 % of males older than 21 (Tables 3, 4). Spearman rho correlation was performed to assess the strength and direction of the linear relationship between pulp visualization stage and chronological age; it was found that there was a strong positive correlation between the two variables, for both genders (Spearman q = 0.420, p \ 0.001 and Spearman q = 0.454, p \ 0.001, for males and females respectively). A logistic regression analysis was performed for each sex, with age (coded into older or younger than 21 years of age) as a dependent variable, and pulp visibility stage as the predictor variable. For females, a total of 228 cases were analyzed and the full model significantly predicted pulp stage (omnibus Chi square = 48.61, df = 1, p \ 0.0005). The model accounted for between 19.2 and 30.3 % of the variance in age, with 96.2 % of the females over 21 years of age successfully predicted. However, only 19.6 % of predictions for females younger than 21 were accurate. Overall, 80.7 % of predictions were accurate. Table 5 gives coefficients and the Wald statistic and associated degrees of freedom and probability values for the predictor variable. For males, a total of 259 cases were analyzed and the full model significantly predicted pulp stage (omnibus Chi square = 50.86, df = 1, p \ 0.0005). The model accounted for between 17.8 and 26.6 % of the variance in age, with 96.9 % of the males over 21 years of age successfully predicted. However, only 27.0 % of predictions for males younger than 21 were accurate. Overall, 79.9 % of predictions were accurate. Table 5 gives coefficients and the Wald
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Forensic Sci Med Pathol (2015) 11:339–344
Table 2 Descriptive analyses of the different stages of visualization of the root pulp according to age
Sex
Female
Male
Stage
Age (in years)
Age (in years)
n
Mean
SD
Minimum
Maximum
n
Mean
SD
Minimum
Maximum 30.0
0
16
20.3
2.1
17.0
25.2
23
21.1
3.2
18.2
1
60
22.2
2.5
17.4
29.1
55
21.9
2.7
18.4
28.7
2
108
24.9
3.2
18.8
30.8
133
24.7
3.3
18.1
30.6
3
44
25.3
2.7
21.2
30.9
48
26.6
3.2
19.1
30.7
SD standard deviation
Table 3 Stage distribution according to age (under or over 21 years), in females, n (%) Stages
0
1
2
3
Age \21
6 (46.2)
25 (42.4)
11 (10.2)
0 (0)
C21
7 (53.8)
34 (57.6)
97 (89.8)
44 (100)
Total
13 (100)
59 (100)
108 (100)
44 (100)
Table 4 Stage distribution according to age (under or over 21), in males, n (%) Stages
0
1
2
3
17 (73.9)
24 (43.6)
18 (13.5)
4 (8.3)
C21
6 (26.1)
31 (56.4)
115 (86.5)
44 (91.7)
Total
23 (100)
55 (100)
133 (100)
48 (100)
Age \21
statistic and associated degrees of freedom and probability values for the predictor variable. Equations for age prediction were developed for each sex, as follows: • •
Females: Age = -0.993 ? 1.559 9 pulp stage Males: Age = -0.981 ? 1.324 9 pulp stage
Discussion Determining if a person over the age of 18 years is also over the 21 years of age threshold can be of utmost importance, since in some countries, the legal age is 21, and not 18 years-old. Traditionally, for determining age over 14 years, third molar mineralization analysis is used. Still, often the mineralization process in these teeth is completed around age 20. Hence, the development of new methodologies focusing on this age threshold is mandatory. AGFAD recommends that when skeletal development of the hand is completed, an examination of the clavicles
123
(X-ray examination or CT scan) should be performed [4]. Several authors [7, 9] state that this analysis can be very useful to determine whether an individual has attained 21 years of age or not. On the other hand, it has been stated that studying clavicle ossification only provides information until the age of 19 years [8] and, additionally, it can be difficult to determine the ossification stage of the medial clavicular epiphyseal cartilage based on conventional postero-anterior radiographic images due to the superimposition of other structures and discrepancies in staging between cases assessed by conventional radiography and CT [20]. Furthermore, it can be expensive and health issues may also rise, since another X-ray must be performed. Additionally, the ossification rate can be affected by the socio-economic status of the patient, meaning that the use of X-ray standards on a person of a lower socio-economic status than that of the reference population usually leads to an underestimation of their age [21]. Still, similarly to other skeletal maturation methods, there is a low impact of ethnicity, allowing X-ray standards for forensic age estimation to be applied in different ethnic groups, regardless of the reference population sample. In an attempt to overcome the problems referred to above, some alternate methodologies for determining age have been proposed. One of those methodologies is the visualization of the periodontal ligament in lower third molars, which was proposed by Olze et al. [3], the main advantage of which is, perhaps, that it relies on an OPT observation. We tested this methodology in a previous investigation in a Portuguese population and have found it can be applicable in males, whereas in females, another marker should be used [17]. In the present investigation we have tried to overcome these shortcomings and have used another methodology proposed by Olze et al. [18] which assesses the root pulp visibility in third molars. No significant intra- or inter-observer differences were found, indicating the reliability and reproducibility of this method. A positive correlation between age and root pulp staging, for both males and females (Spearman q = 0.420, p \ 0.001 and Spearman q = 0.454, p \ 0.001, respectively) was found. The positive rho correlation indicates
Forensic Sci Med Pathol (2015) 11:339–344 Table 5 Coefficients, the Wald statistic and associated degrees of freedom, and probability values for the pulp stage visibility
Sex
343
B
SE
Wald
df
Sig.
Exp(B)
95.0 % CI for Exp(B) Lower
Upper
2.849
7.936
2.496
5.659
Females Pulp stage Constant
1.559
0.261
35.597
1
0.000
4.755
-0.993
0.394
6.350
1
0.012
0.370
1.324
0.209
40.171
1
0.000
3.758
-0.981
0.346
8.030
1
0.005
0.375
Males Pulp stage Constant
that as age increases so does the pulp stage. Regarding the strength of the relationship, different authors suggest different interpretations; however, Cohen [22] suggests the following guidelines: • • •
r = 0.10–0.29 or r = -0.10 to -0.29, small; r = 0.30–0.49 or r = -0.30 to -0.49, medium; r = 0.50–1.0 or r = -0.50 to -1.0, large;
The strength of the relationship was considered as medium, which agrees with data from other authors [18]. Nevertheless, some differences were also noticed. For instance, Olze et al. [18]. stated that if stage 1 was observed the examined individual is most probably over 21 years of age and if stages 2 and 3 were observed the age can safely be stated to be over 21 years of age. Our results do not agree with these data, since almost half of the stage 1 females (42.4 %) and males (43.6 %) were younger than 21 years of age. Stage 2 did account for a better discriminatory capacity; 10.2 % of the females and 13.5 % of the males in stage 2 were younger than 21 years of age. On the other hand, stage 3 proved to be a very useful marker, since all the females in stage 3 were older than 21 years of age; for males, the results were not as discriminatory and 8.3 % of the stage 3 males were younger than 21. The model for each sex, with age as a dependent variable, and pulp visibility stage as the predictor variable, successfully predicted age over 21 years in 96.2 % of the females and in 96.9 % of the males. However, only 19.6 % and 27.0 % of predictions were accurate for the group younger than 21 years, for females and males respectively. This means that using the different stages of pulp visibility as an age marker may not be suitable, as it may produce ethically unacceptable errors by claiming that a person is older than they really are. Nevertheless, a specific stage can be used as an age marker. That being said, one can state that in females in this sample, root pulp stage 3 can be used as a marker for age over 21 years. However, in males, other markers should be used, since root pulp visibility staging can produce ethically unacceptable errors, namely stating that a person is older than they are. In fact, according to Garamendi et al. [8], in forensic age estimation two types of errors can occur: technically unacceptable errors and ethically unacceptable. The first are incorrect
estimates that lead to a more benevolent criminal treatment and may also generate social expenses due to the need of special protective measures implementation. The latter leads to a violation of the minor’s rights. Consequently, in forensic age estimation, although all errors should be kept to minimum, ethically unacceptable errors should, in fact, be eliminated. Hence, the recommendation for an additional marker for forensic age estimation in males is made.
Conclusions Root pulp visualization of lower third molars may become an important methodology in forensic age estimation. In this population, stage 3 can be used to state that a female person is over 21 years-old; for males, other markers should be used. Differences between studies are evident, suggesting that specific population standards should be used when applying this technique.
Key points 1. 2.
3. 4. 5.
Third molar mineralization may not be a useful technique for forensic age estimation over age 18. New methodologies to determine age are required since the attainment of 21 years may be a useful marker for legal investigations. The visualization of the third molar root pulp is a process related with age. Stage 3 can be used to state that a person is over 21 years-old in females of our study population. Differences between studies in different populations are evident, suggesting that specific population standards should be used when applying this technique.
References 1. Karaarslan K, Karaarslan ES, Ozesevik AS, Ertas E. Age estimation for dental patients using orthopantographs. Eur J Dent. 2010;4:389–94.
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344 2. Olze A, Bilang D, Schmidt S, Wernecke KD, Geserick G, Schmeling A. Validation of common classification systems for assessing the mineralization of third molars. Int J Legal Med. 2005;119:22–6. 3. Olze A, Solheim T, Schulz R, Kupfer M, Pfeifer H, Schmeling A. Assessment of the radiographic visibility of the periodontal ligament in the lower third molars for the purpose of forensic age estimation in living individuals. Int J Legal Med. 2010;124:445–8. 4. Schmeling A, Grundmann C, Fuhrmann A, Kaatsch HJ, Knell B, Ramsthaler F, et al. Criteria for age estimation in living individuals. Int J Legal Med. 2008;122(6):457–60. 5. Schmeling A, Reisinger W, Geserick G, Olze A. The current state of forensic age estimation of live subjects for purpose of criminal prosecution. Forensic Sci Med Pathol. 2005;1(4):465–9. 6. Knell B, Ruhstaller P, Schmeling A. Dental age diagnostics by means of radiographical evaluation of the growth stages of lower wisdom teeth. Int J Legal Med. 2009;123(6):465–9. 7. Schmeling A, Schulz R, Reisinger W, Mu¨hler M, Wernecke KD, Geserick G. Studies on the time frame for ossification of the medial clavicular epiphyseal cartilage in conventional radiography. Int J Legal Med. 2004;118:5–8. 8. Garamendi PM, Landa MI, Botella MC, Alema´n I. Forensic age estimation on digital X-ray images: medial epiphyses of the clavicle and first rib ossification in relation to chronological age. J Forensic Sci. 2011;56(1):S3–12. 9. Kellinghaus M, Schulz R, Vieth V, Schmidt S, Schmeling A. Forensic age estimation in living subjects based on the ossification status of the medial clavicular epiphhysis as revealed by thinslice multidetector computed tomography. Int J Legal Med. 2010;124:149–54. 10. Garamendi PM, Landa MI, Ballesteros J, Solano MA. Reliability of the methods applied to assess age minority in living subjects around 18 years old. A survey on a Moroccan origin population. Forensic Sci Int. 2005;154(1):3–12. 11. Caldas IM, Ju´lio P, Simo˜es RJ, Matos E, Afonso A, Magalha˜es T. Chronological age estimation based on third molar development in a Portuguese population. Int J Legal Med. 2011;125(2):235–43.
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Forensic Sci Med Pathol (2015) 11:339–344 12. Olze A, Peschke C, Schulz R, Schmeling A. Studies of the chronological course of wisdom tooth eruption in a German population. J Forensic Leg Med. 2008;15:426–9. 13. Orhan K, Ozer L, Orhan AI, Dogan S, Paksoy CS. Radiographic evaluation of third molar development in relation to chronological age among Turkish children and youth. Forensic Sci Int. 2007;165(1):46–51. 14. Prieto JL, Barberia E, Ortega R, Magana C. Evaluation of chronological age based on third molar development in the Spanish population. Int J Legal Med. 2005;119(6):349–54. 15. Zeng DL, Wu ZL, Cui MY. Chronological age estimation of third molar mineralization of Han in southern China. Int J Legal Med. 2010;124(2):119–23. 16. Olze A, Pynn BR, Kraul V, Schulz R, Heinecke A, Pfeiffer H, et al. Studies on the chronology of third molar mineralization in first Nations people of Canada. Int J Legal Med. 2010;124(5):433–7. 17. Sequeira CD, Teixeira A, Caldas IM, Afonso A, Perez-Mongiovi D. Age estimation using the radiographic visibility of the periodontal ligament in lower third molars in a Portuguese population. J Clin Exp Dent. 2014;6(5):e546–50. 18. Olze A, Solheim T, Schulz R, Kupfer M, Schmeling A. Evaluation of the radiographic visibility of the root pulp in the lower third molars for the purpose of forensic age estimation in living individuals. Int J Legal Med. 2010;124(3):183–6. 19. Caldas IM, Carneiro JL, Teixeira A, Matos E, Afonso A, Magalha˜es T. Chronological course of third molar eruption in a Portuguese population. Int J Legal Med. 2012;126:107–12. 20. Schulz R, Muhler M, Reisinger W, Schmidt S, Schmeling A. Radiographic staging of ossification of the medial clavicular epiphysis. Int J Legal Med. 2008;122(1):55–8. 21. Schmeling A, Reisinger W, Loreck D, Vendura K, Markus W, Geserick G. Effects of ethnicity on skeletal maturation: consequences for forensic age estimations. Int J Legal Med. 2000;113(5):253–8. 22. Cohen JW. Statistical power analysis for the behavioral sciences. 2nd ed. Hillsdale, NJ: Lawrence Erlbaum Associates; 1989.
ORIGINAL ARTICLE
The radiographic visibility of the root pulp of the third lower molar as an age marker Daniel Pe´rez-Mongiovi1 • Alexandra Teixeira2 • Ineˆs Morais Caldas3,4
Accepted: 10 June 2015 / Published online: 24 June 2015 Springer Science+Business Media New York 2015
Abstract Purpose The aim of this work was to determine the usefulness of the visibility of the dental pulp in lower third molars in forensic age estimation. Methods Dental pulp visibility on lower third molars was assessed using a sample of 487 orthopantomograms. Intra and inter-observer agreement was determined using the Cohen’s kappa test. A descriptive analysis of the stages according to age was done. The relationship between age and stage attainment was assessed using Chi square test and the strength and direction of the linear relationship between pulp visualization stage and chronological age was evaluated using Spearman rank order correlation (rho). Equations for predicting an age above 21 years were developed using logistic regression. The level of significance was defined at p \ 0.05. Results The relationship between age and stage attainment had statistical significance for both sexes (p \ 0.001). There was a medium positive correlation between the two variables for both genders (Spearman q = 0.420, p \ 0.001 and Spearman q = 0.454, p \ 0.001, for males
& Ineˆs Morais Caldas [email protected] 1
Department of Sciences, Advanced Institute of Health Sciences-North (ISCS-N), CESPU, CRL, Rua Central de Gandra, 13174585-116 Gandra PRD, Portugal
2
Private Practice, Porto, Portugal
3
Faculty of Dental Medicine of the University of Porto, Faculdade de Medicina Denta´ria da Universidade do Porto, Rua Dr. Manuel Pereira da Silva, 4200-393 Porto, Portugal
4
CENCIFOR - Center of Forensic Sciences, Associac¸a˜o Centro de Cieˆncias Forenses, Largo da Se´ Nova, INML IP, 3000-213 Coimbra, Portugal
and females respectively). The model built for age estimation successfully predicted age over 21 in 96.2 % of the females and in 96.9 % of the males. However, only 19.6 and 27.0 % of predictions were accurate for the group that was younger than 21, for females and males, respectively. Conclusions The accuracy of predictions for the group younger than 21 years of age was low, meaning that this methodology may not be suitable for age estimation. Still, stage 3 alone proved to be a suitable age marker for determining an age over 21 years. Keywords Forensic sciences Forensic odontology Age estimation Third molar Pulp visibility
Introduction Currently, mainly due to problems arising from globalization, forensic age estimation has become increasingly important. In fact, the increasing number of non-national subjects with doubtful information regarding their birth date makes forensic age estimation necessary in several contexts, namely in the course of criminal, civil, or asylum proceedings [1–7]. Meanwhile, the Study Group on Forensic Age Diagnostics (Arbeitsgemeinschaft fu¨r Forensische Altersdiagnostik, AGFAD) has proposed guidelines for forensic age estimation. These consist of: (a) a clinic examination, performing anthropometric measures and assessment of sexual maturity signs; (b) an X-ray examination of the left hand; (c) a dental evaluation with a clinical examination and analysis of an orthopantogram (OPT); and (d) an X-ray examination or CT scan of the clavicles when hand skeletal development is completed [4, 6–10]. The information that is needed often relates to the probability of an individual being older than 14, 16, 18, or
123
340
21 years old [4, 11, 12]; the third molars may be the only teeth that can be used to provide valuable information since they have not finished their developmental processes at these ages. However, the mineralization process may be completed before age 21 [13, 14] or even before age 18 [11, 15, 16]. In the Portuguese population, a previous study has showed that stage H of the eight-grade Demirjian scheme was found to be a useful marker for diagnosing an age equal to or older than 18 years, in both males and females [12], but for determining an age equal to or older than 21 years this methodology showed no usefulness, as most teeth have already completed their root development by the age of 18 years. Recently several new dental techniques have been proposed to estimate age in these cases. For instance, Olze et al. [3] referred to the use of the periodontal ligament in the lower third molars as potential age estimation criterion after completed formation of the root. We have already tested this methodology in a previous study [17] and found that there was a statistically significant relationship between age and stage of periodontal ligament development for both sexes. Furthermore, the results indicated that stage 3 of periodontal ligament visibility (i.e., when the periodontal ligament is invisible along almost the full length of two roots) could be used to state that a male is over 21 years-old; however, in females, the technique was not as accurate, and we have concluded that another marker should be used for this purpose in females. Olze et al. [18] described another methodology for forensic age estimation, using the radiographic visibility of the root pulp in the lower third molars. According to the authors, this methodology can be useful for determining both an age over 18 years as well as an age over 21-years. Thus, similarly to what we have done previously with the visibility of the periodontal ligament, the aim of this work is to assess the radiographic visibility of the root pulp in third molars, using OPT from a Portuguese population, in order to determine the suitability of this methodology in forensic age assessment, especially for determining an age over 21 years.
Materials and methods A total of 487 OPTs from Portuguese subjects aged from 17 to 30 years was assessed; 228 belonged to females, and 259 to males; subjects were divided into two groups: group a: age below 21 years; group b: age equal to or older than 21 years. Subjects attended the residency dental clinic of the Faculty of Dental Medicine of University of Porto. OPTs were taken from each subject for diagnostic purposes, and their date of birth was recorded but not revealed to the examiners. The socioeconomic background of the sample population we studied can be described as middle
123
Forensic Sci Med Pathol (2015) 11:339–344
to low and the general health status of the study population was good, with no known systemic pathologies. The population affinity of the study subjects could not be verified, however all subjects had Portuguese last names and it was assumed they were born and lived in Portugal (other authors have previously adopted the procedure of assuming ethnicity based on last name, in similar circumstances [3, 11, 19]). All OPTs with unclear images, or presenting impacted third lower molars, or with incomplete root formation, carious lesions or endodontic treatment were excluded. Third molars with a single root were excluded, as the four stages could not be applied. Age and sex distribution of the material can be observed in Table 1. The visibility of the root pulp of lower third molars with completed root formation (including apical closure) was recorded, as defined by Olze et al. [18] in the following four stages (Fig. 1): • • •
•
Stage 0: The root pulp is visible along the full length of all roots; Stage 1: The root pulp is invisible in one root from apex to more than half root; Stage 2: The root pulp is invisible along almost the full length of one root or along part of the root in two roots or both; Stage 3: The root pulp is invisible along almost the full length of two roots.
The root pulp visibility was assessed in the left lower third molar (38) and, when this tooth presented any of the exclusion criteria referred, the right lower third molar (48) was used. Table 1 Age and sex distribution of the sample population Age
Females n (%)
Males n (%)
17.0–17.9
4 (1.75)
0
18.0–18.9
6 (2.63)
14 (5.41)
19.0–19.9
13 (5.70)
26 (10.04)
20.0–20.9 21.0–21.9
23 (10.09) 22 (9.65)
23 (8.89) 30 (11.58)
22.0–22.9
27 (11.84)
17 (6.56)
23.0–23.9
22 (9.65)
18 (6.95)
24.0–24.9
17 (7.46)
23 (8.89)
25.0–25.9
21 (9.21)
21 (8.11)
26.0–26.9
22 (9.65)
17 (6.56)
27.0–27.9
14 (6.14)
22 (8.49)
28.0–28.9
12 (5.26)
19 (7.34)
29.0–29.9
14 (6.14)
11 (4.25)
30.0–30.9
11 (4.82)
18 (6.95)
Total
228
259
Forensic Sci Med Pathol (2015) 11:339–344
341
Fig. 1 Schematic drawings and pictures of stages of radiographic visibility of the root pulp in lower molars (adapted from [18])
To assess reliability, 30 randomly selected OPTs were examined by two authors (DPM and AT), and 30 randomly selected OPTs were assessed twice by the first author, with a 1 month interval between the two observations. Intra and inter-observer agreement was determined using the Cohen’s kappa test. A descriptive analysis of the stages of visualization of the root pulp according to age was done. The relationship between age and stage attainment was assessed using a Chi square test and the strength and direction of the linear relationship between pulp visualization stage and chronological age was evaluated using Spearman rank order correlation (rho). Equations for predicting an age over 21 were developed using logistic regression. The level of significance was defined at p \ 0.05. Microsoft Excel (Microsoft Corp., Redmond, WA, USA) was used for data registration and IBM SPSS Statistics 22 (SPSS Inc., Chicago, IL, USA) was used for statistical analyses. This study was submitted and approved by the Ethical Board of the Faculty of Dental Medicine of University of Porto.
Results Repeated scoring of 30 radiographs revealed good agreement in both cases (k [ 0.80), indicating that there was high reproducibility and repeatability. Stage 0 first appeared at 18.2 and 17.0 years, for males and females respectively. Stage 1 was first attained at 18.4 years for males, and 17.4 years for females. Stage 2 was achieved first at 18.8 years for females and 18.1 years in males. The earliest appearance of stage 3 happened at
age 19.1 years for males and 21.2 years for females (Table 2). The relationship between age and stage attainment had statistical significance for both sexes (p \ 0.001). Stage 3 was only attained by females older than 21 years of age and by 91.7 % of males older than 21 (Tables 3, 4). Spearman rho correlation was performed to assess the strength and direction of the linear relationship between pulp visualization stage and chronological age; it was found that there was a strong positive correlation between the two variables, for both genders (Spearman q = 0.420, p \ 0.001 and Spearman q = 0.454, p \ 0.001, for males and females respectively). A logistic regression analysis was performed for each sex, with age (coded into older or younger than 21 years of age) as a dependent variable, and pulp visibility stage as the predictor variable. For females, a total of 228 cases were analyzed and the full model significantly predicted pulp stage (omnibus Chi square = 48.61, df = 1, p \ 0.0005). The model accounted for between 19.2 and 30.3 % of the variance in age, with 96.2 % of the females over 21 years of age successfully predicted. However, only 19.6 % of predictions for females younger than 21 were accurate. Overall, 80.7 % of predictions were accurate. Table 5 gives coefficients and the Wald statistic and associated degrees of freedom and probability values for the predictor variable. For males, a total of 259 cases were analyzed and the full model significantly predicted pulp stage (omnibus Chi square = 50.86, df = 1, p \ 0.0005). The model accounted for between 17.8 and 26.6 % of the variance in age, with 96.9 % of the males over 21 years of age successfully predicted. However, only 27.0 % of predictions for males younger than 21 were accurate. Overall, 79.9 % of predictions were accurate. Table 5 gives coefficients and the Wald
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Table 2 Descriptive analyses of the different stages of visualization of the root pulp according to age
Sex
Female
Male
Stage
Age (in years)
Age (in years)
n
Mean
SD
Minimum
Maximum
n
Mean
SD
Minimum
Maximum 30.0
0
16
20.3
2.1
17.0
25.2
23
21.1
3.2
18.2
1
60
22.2
2.5
17.4
29.1
55
21.9
2.7
18.4
28.7
2
108
24.9
3.2
18.8
30.8
133
24.7
3.3
18.1
30.6
3
44
25.3
2.7
21.2
30.9
48
26.6
3.2
19.1
30.7
SD standard deviation
Table 3 Stage distribution according to age (under or over 21 years), in females, n (%) Stages
0
1
2
3
Age \21
6 (46.2)
25 (42.4)
11 (10.2)
0 (0)
C21
7 (53.8)
34 (57.6)
97 (89.8)
44 (100)
Total
13 (100)
59 (100)
108 (100)
44 (100)
Table 4 Stage distribution according to age (under or over 21), in males, n (%) Stages
0
1
2
3
17 (73.9)
24 (43.6)
18 (13.5)
4 (8.3)
C21
6 (26.1)
31 (56.4)
115 (86.5)
44 (91.7)
Total
23 (100)
55 (100)
133 (100)
48 (100)
Age \21
statistic and associated degrees of freedom and probability values for the predictor variable. Equations for age prediction were developed for each sex, as follows: • •
Females: Age = -0.993 ? 1.559 9 pulp stage Males: Age = -0.981 ? 1.324 9 pulp stage
Discussion Determining if a person over the age of 18 years is also over the 21 years of age threshold can be of utmost importance, since in some countries, the legal age is 21, and not 18 years-old. Traditionally, for determining age over 14 years, third molar mineralization analysis is used. Still, often the mineralization process in these teeth is completed around age 20. Hence, the development of new methodologies focusing on this age threshold is mandatory. AGFAD recommends that when skeletal development of the hand is completed, an examination of the clavicles
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(X-ray examination or CT scan) should be performed [4]. Several authors [7, 9] state that this analysis can be very useful to determine whether an individual has attained 21 years of age or not. On the other hand, it has been stated that studying clavicle ossification only provides information until the age of 19 years [8] and, additionally, it can be difficult to determine the ossification stage of the medial clavicular epiphyseal cartilage based on conventional postero-anterior radiographic images due to the superimposition of other structures and discrepancies in staging between cases assessed by conventional radiography and CT [20]. Furthermore, it can be expensive and health issues may also rise, since another X-ray must be performed. Additionally, the ossification rate can be affected by the socio-economic status of the patient, meaning that the use of X-ray standards on a person of a lower socio-economic status than that of the reference population usually leads to an underestimation of their age [21]. Still, similarly to other skeletal maturation methods, there is a low impact of ethnicity, allowing X-ray standards for forensic age estimation to be applied in different ethnic groups, regardless of the reference population sample. In an attempt to overcome the problems referred to above, some alternate methodologies for determining age have been proposed. One of those methodologies is the visualization of the periodontal ligament in lower third molars, which was proposed by Olze et al. [3], the main advantage of which is, perhaps, that it relies on an OPT observation. We tested this methodology in a previous investigation in a Portuguese population and have found it can be applicable in males, whereas in females, another marker should be used [17]. In the present investigation we have tried to overcome these shortcomings and have used another methodology proposed by Olze et al. [18] which assesses the root pulp visibility in third molars. No significant intra- or inter-observer differences were found, indicating the reliability and reproducibility of this method. A positive correlation between age and root pulp staging, for both males and females (Spearman q = 0.420, p \ 0.001 and Spearman q = 0.454, p \ 0.001, respectively) was found. The positive rho correlation indicates
Forensic Sci Med Pathol (2015) 11:339–344 Table 5 Coefficients, the Wald statistic and associated degrees of freedom, and probability values for the pulp stage visibility
Sex
343
B
SE
Wald
df
Sig.
Exp(B)
95.0 % CI for Exp(B) Lower
Upper
2.849
7.936
2.496
5.659
Females Pulp stage Constant
1.559
0.261
35.597
1
0.000
4.755
-0.993
0.394
6.350
1
0.012
0.370
1.324
0.209
40.171
1
0.000
3.758
-0.981
0.346
8.030
1
0.005
0.375
Males Pulp stage Constant
that as age increases so does the pulp stage. Regarding the strength of the relationship, different authors suggest different interpretations; however, Cohen [22] suggests the following guidelines: • • •
r = 0.10–0.29 or r = -0.10 to -0.29, small; r = 0.30–0.49 or r = -0.30 to -0.49, medium; r = 0.50–1.0 or r = -0.50 to -1.0, large;
The strength of the relationship was considered as medium, which agrees with data from other authors [18]. Nevertheless, some differences were also noticed. For instance, Olze et al. [18]. stated that if stage 1 was observed the examined individual is most probably over 21 years of age and if stages 2 and 3 were observed the age can safely be stated to be over 21 years of age. Our results do not agree with these data, since almost half of the stage 1 females (42.4 %) and males (43.6 %) were younger than 21 years of age. Stage 2 did account for a better discriminatory capacity; 10.2 % of the females and 13.5 % of the males in stage 2 were younger than 21 years of age. On the other hand, stage 3 proved to be a very useful marker, since all the females in stage 3 were older than 21 years of age; for males, the results were not as discriminatory and 8.3 % of the stage 3 males were younger than 21. The model for each sex, with age as a dependent variable, and pulp visibility stage as the predictor variable, successfully predicted age over 21 years in 96.2 % of the females and in 96.9 % of the males. However, only 19.6 % and 27.0 % of predictions were accurate for the group younger than 21 years, for females and males respectively. This means that using the different stages of pulp visibility as an age marker may not be suitable, as it may produce ethically unacceptable errors by claiming that a person is older than they really are. Nevertheless, a specific stage can be used as an age marker. That being said, one can state that in females in this sample, root pulp stage 3 can be used as a marker for age over 21 years. However, in males, other markers should be used, since root pulp visibility staging can produce ethically unacceptable errors, namely stating that a person is older than they are. In fact, according to Garamendi et al. [8], in forensic age estimation two types of errors can occur: technically unacceptable errors and ethically unacceptable. The first are incorrect
estimates that lead to a more benevolent criminal treatment and may also generate social expenses due to the need of special protective measures implementation. The latter leads to a violation of the minor’s rights. Consequently, in forensic age estimation, although all errors should be kept to minimum, ethically unacceptable errors should, in fact, be eliminated. Hence, the recommendation for an additional marker for forensic age estimation in males is made.
Conclusions Root pulp visualization of lower third molars may become an important methodology in forensic age estimation. In this population, stage 3 can be used to state that a female person is over 21 years-old; for males, other markers should be used. Differences between studies are evident, suggesting that specific population standards should be used when applying this technique.
Key points 1. 2.
3. 4. 5.
Third molar mineralization may not be a useful technique for forensic age estimation over age 18. New methodologies to determine age are required since the attainment of 21 years may be a useful marker for legal investigations. The visualization of the third molar root pulp is a process related with age. Stage 3 can be used to state that a person is over 21 years-old in females of our study population. Differences between studies in different populations are evident, suggesting that specific population standards should be used when applying this technique.
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