SCIJUS-00512; No of Pages 5 Science and Justice xxx (2015) xxx–xxx
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Third molar observations in a sample of British male young offenders Sally E. Andrews Bengough's Lodge, Breadstone, Berkeley, Glos GL13 9 HF, United Kingdom
a r t i c l e
i n f o
Article history: Received 4 May 2014 Received in revised form 22 February 2015 Accepted 25 February 2015 Available online xxxx Keywords: Dental Third molar Development
a b s t r a c t Development, morphology and eruption of third molars are highly variable, and it is generally accepted that the emergence time is between the ages of 17 and 21 years. This study reports on variation in timing encountered in a sample of 155 young males (15–18 years) of British nationality who were detained at Her Majesty's Prison and Young Offenders Institution (HMP&YOI) Ashfield as young offenders. All 155 participants were self-reported in terms of their chronological age and their ethnic origin. Of the 17 year-olds, 68% of Black males displayed one or more erupted third molars compared to 39% of the White males. For those who were of mixed ancestry, 50% showed evidence of eruption of at least one third molar in this age group. This difference between Black and White ethnicity was further supported when missing first or second molars were taken into consideration. Whilst it has been suggested in the literature that ethnicity plays no major part in eruption timings for the third molars, this clinical observation poses some interesting questions about the accuracy of dental age assessment. © 2015 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction Dental age assessment is acknowledged as an important, although not necessarily precise, process for assigning age around the 18 year threshold and is utilised when individuals present without documentation, for example, asylum seekers, disaster victims, forensic and archaeological cases [1]. The accuracy of age assessment can have far reaching implications for those who seek protection under international humanitarian laws and for those who are sentenced under criminal law [2]. Population differences in third molar development had been reported until the early 1960's [3,4] yet interest in this appeared to wane when investigation into tooth development using radiographic methods seemed to take precedence with little attention to ethnicity [5,6]. However, in more recent years, there has been a resurgence of interest reflecting the legal requirement to assign an age to an individual who attempts to enter a country without documentation or who comes to the attention of the courts without possessing the authorised means to confirm their age. Population differences in dental development are being investigated more thoroughly and there is increasing debate surrounding possible ethnic, geographical or social causes and their significance [7,8]. Even though some ethnic differences have been reported in the literature, it has been suggested that geographical or environmental effects may be of greater relevance [9], and some debate as to whether ethnic differences can be substantiated [10,11]. It has also been suggested that steroid hormones could be involved with dental development [8,12].
E-mail address: [email protected].
Based on data from Schour and Massler [13], standard textbooks cite 17–21 years as the standard eruption time for third molars which are the most variable of all human teeth. The atlas approach of pictorial comparison is widely used for dental assessments in individuals under 15 years of age but precision is lost in the older stages of childhood, mainly because all teeth but the third molars have completed their development. More recently, the London Atlas [14] has provided one pictorial representation for each year between 16.5 and 23.5 years of age. Demirjian et al. [5] and Moorrees [6] have established age estimation systems relying on radiographic appearance of developing teeth. These are well-accepted methods and very good correlation between the estimated age and actual age has been reported [15]. Demirjian's method, incorporating the third molar, has been used to evaluate third molars in a number of populations including American Black and White, British, Texas Hispanic and Indian [1,16–19]. Using clinical and radiological methods, studies have confirmed wide age ranges at each third molar stage [3,4,8,16,18–29] and, whilst highlighting the need for more population-specific data, have specifically suggested that ancestry affects the development of third molars. Odusanya and Abayomi [21] studied third molars in 258 Nigerian adolescents and found that the average age at initial clinical eruption was as young as 13 for females and 15 for males. Moreover, all third molars had clinically erupted by age 19 and lower molars erupted before upper molars in both sexes. Harris [8] has highlighted significant ethnic variation in a sample of American Blacks and Whites. Blankenship et al. [16] found third molar developmental stages occurring a year or so earlier in American Blacks compared to Whites, and earlier in males than females. They stated that the likelihood that an African American having fully developed third molars and is at least
http://dx.doi.org/10.1016/j.scijus.2015.02.005 1355-0306/© 2015 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
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S.E. Andrews / Science and Justice xxx (2015) xxx–xxx
18 years old is 93%, and 90% for Whites. Using their own and worldwide data, Liversidge and Marsden [10] also calculated the probability of an individual being over or under 18 on the basis of third molar development. They concluded that, for all populations, if the third molar has its apex half or fully complete, age is more than likely to be at least 18 and reported that a single individual from any ethnic group is not significantly different from one in any other group. Demirjian's method for assessment of tooth development requires a radiograph to be taken. As a general rule, radiographs should only be taken to benefit a person's health. There is no therapeutic benefit in taking a radiograph for age estimation and informed consent becomes dubious if a child feels under pressure to agree to a radiograph in order for an asylum claim to be properly dealt with. Considering these two issues together with lack of accuracy in age determination, it has been argued that exposure to radiation would unlawfully inflict harm upon a person [30]. However, Demirjian's method is considered to be one of the most reliable methods to conduct age assessment in children and young adults. As justice hangs on the outcome of the age assessment, it is imperative that it must be accurate in order to justify the exposure to radiation. Without radiographs, forensic odontologists would lose the benefit of Demirjian's methods and would have to be reliant upon clinical eruption of teeth. The likelihood of successful eruption can be improved markedly by removing a molar anterior to a third molar lacking space. Fanning [4] showed that third molars emerge earlier when teeth anterior to them have been removed and pointed out the importance of comparing third molar eruption in “non-mutilated” dentitions. Another factor is agenesis, or failure of formation, which is not an uncommon for third molars but its incidence varies. Chagula [3] quotes studies ranging from as much as 30% in Chinese to 0% in West African Negroes and gives 1.6% in his own study of East Africans. In White American women third molar agenesis has been put at 9% by Nanda [31] and also at 9% in Whites by Levesque et al. [32]. In a study by Forjani et al. [33] of White and Bangladeshi UK citizens, all with third molar agenesis, one missing third molar was found in 45% of the sample, whilst 34% had 2 missing third molars, 6% had 3 missing and 15% had agenesis of all four third molars. The aim of this study was to assess whether there is ethnic variation in third molar emergence by evaluating ethnically diverse young male offenders at HMP&YOI Ashfield. 2. Methods Ethical permission was granted by the University of Glamorgan Ethics Committee and HMP&YOI Ashfield for every young person (YP)
attending the dental unit for treatment to be invited to take part in the study. At the time of the study, HMP&YOI Ashfield accommodated up to 400 males between the ages of 15 and 18 years, representing about 18% of the UK young male offender population. The proportions of ethnic groups in young offenders' institutions (YOI) differ in comparison with the general population. The majority are White, but Black and Minority Ethnic (BME) groups are significantly over-represented compared to the general population. The following data was collected for each individual: date of birth, confirmation of UK citizenship and upbringing, self-assessed ethnicity, any relevant medical history, medication, missing teeth and history of extractions. Third molars were assessed by clinical observation only and data recorded on one single visit. No radiographs were taken for the purposes of this research and therefore it is accepted that missing, unerupted and/or impacted third molars could not be assessed. If not visible, third molars were classified as unerupted. Eruption, or gingival emergence, was defined as penetration of the gingiva by at least one dental cusp. Erupted third molars were further classified as partiallyerupted or, if in occlusion with an opposing tooth, fully-erupted. Participants were asked to self assign to one of fifteen possible ethnic groups (Office of National Statistics classification) and were later assigned by the author to five broader ethnic groups: Asian, Black, White, Mixed or Other. There was a concern that YPs might present with third molar symptoms thereby creating a bias in the sample but this occurred on only one occasion and was not the main presenting complaint. Data was collected from 155 males between the ages of 15 and 18 years. 3. Results The Ashfield sample consisted of 155 British males between 15 and 18 years of age and of diverse ethnicity (Table 1). 88%, were either 16 or 17 years of age, 5% were 15 years of age and 7% had attained 18 years of age. Fifty-six percent of the total sample self-assessed as White, 19% as Black, 17% as being of mixed ethnicities 7% as Asian and 1% gave their ethnicity as “Other”. In total, 83 mandibular and 55 maxillary third molars had emerged. On the left, 27 maxillary and 42 mandibular third molars had emerged (a total of 69 left third molars). On the right, 28 maxillary and 41 mandibular third molars had emerged (a total of 69 right third molars). In the small group of 15 year olds, two of the three Black YPs had erupted third molars and the single mixed ethnicity YP had two partially erupted lower third molars, one in a quadrant where another molar had been lost (Table 2). No third molars were observed in
Table 1 Distribution of ethnic groups in the Ashfield sample of British males. Ethnic group
Age 15
Asian-Indian Asian-Other Asian-Pakistani
Age 16
Age 17
Age 18
Broad ethnic group
Total number (% of total)
1 3 7
Asian
11 (7%)
6 13
9 19 1
Black
29 (19%)
5
Mixed
26 (17%)
1 3
Black-African Black-Caribbean Mixed Black-African/Black-Caribbean
1 2
Mixed Other Black-African/Asian Black-African/Black-African Black-African/Black-Caribbean
1
2 4 1
3 4
4
3 12
6 1 3 16
1
1
2
Other
2 (1%)
11
82 2 1 2
White
87 (56%)
11
155
1
Other
Total number
White-British White-Irish White-Irish traveller White-Other
4
13 1 1
54 1
Total number
8
32
104
2
155
Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
S.E. Andrews / Science and Justice xxx (2015) xxx–xxx Table 2 Number of Ashfield young persons (YP) with erupted third molars (M3), by age and ethnicity. Number of YPs with one or more M3 emerged/total number for that age group and ethnicity
Asian Black Mixed Other White Total
15 year-olds
16 year-olds
17 year-olds
18 year-olds
– 2/3 1/1 – 0/4 3/8
1/4 1/7 2/5 0/1 3/15 7/32
5/7 13/19 10/20 0/1 22/57 50/104
– – – – 3/11 3/11
the four White YPs in this age group. Of the 16 year-olds (n = 32), 14.3% of Black YPs, 40% of the Mixed ethnicity YPs, 25% of the Asian YPs and 20% of White YPs had at least one clinically erupted third molar. For 17 year-olds (n = 104) the small number of Asians had the highest percentage of clinically erupted third molars (71.4%) compared to any other ethnic group at any age; the Black group (68.4%) are also advanced over the White group (38.6%); and the Mixed group (50%) fall between the Black and the White groups. The small group of eleven 18-year-olds were all White and three of those had one or more erupted third molars. As 18 year-olds only stay at Ashfield if their remaining sentence is short, ten of the individuals in this group were aged less than 18 years and 3 months. Of the four major ethnic groupings, the Black 16 year old YPs have the lowest percentage eruption of third molars but by 17 years of age they are almost as high as the Asian group. Those of self-assessed Mixed origin have the highest percentage eruption at 16 years of age and the White teenagers at 17 years have the lowest percentage emergence (Table 2). A Chi square test was applied to investigate statistical association between emergence and ethnic group and a significant difference was only found between 17 year-old Blacks and Whites (p = 0.024). 3.1. Effect of first or second molar extraction Extracted, and therefore missing, first or second molars are a common finding in the Ashfield sample. As first or second molar extraction can affect third molar eruption success, results for percentages of maxillary and mandibular third molars erupted in 17 year-old YPs with and without previous extraction of molars in the same quadrant are shown in Table 3. For example, the chance of a maxillary third molar being present when no other molars in the same quadrant had been removed was 24.6%, or 43 out of a possible 175 cases. 3.2. Comparison of non-mutilated dentitions in Ashfield Black and White ethnic groups The percentage of Black YPs aged 17 without molar extractions and with one or more erupted third molars is 60%. This represents 9 YPs in a group of 15; and 5 of them, or 33%, had all 4 third molars erupted. In comparison, there were 39 White 17 year-olds without molar extractions and 12 of them, or 30.8%, had at least one erupted third molar and 7.7% had 4 erupted third molars.
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Table 4 Table to show 16.75–18.25 year-old White and Black groups and “non-mutilated” third molar (M3) status. Presence of 1 or more
Ashfield
Ashfield
M3 without molar extraction Yes No Chi square = 5.49
White 14 37 Degrees of freedom = 1
Black 10 7 P = 0.019
To further compare the “non-mutilated dentitions” of Ashfield Black and White groups, YPs aged 16.75 years–18.25 years were used (Table 4). This age group was chosen because 10 of the 11 18-yearolds at Ashfield were within this range; and extending the 17 year-old sample by 3 months either side provided a larger sample for this comparison. Having discounted any individuals with missing first or second molars, a sample of 17 Black YPs and 51 White YPs remained. 19.6% of the White and 58.8% of the Black group had clinically erupted third molars in non-mutilated dentitions. The Chi square test shows a strong association (p = 0.019) between ethnicity and erupted third molars at age 16.75 to 18.25 years. The Black group at Ashfield is ahead of the White group. It was also noted that eleven YPs in the Ashfield sample, or 7%, had been diagnosed with attention deficit hyperactivity disorder (ADHD). Eight of these were White 17 year-olds of whom four had at least one erupted third molar. The Ashfield results for percentages of one or more third molars clinically erupted were compared with those from studies by Chagula [3], Fanning [4] and Hassanali [20] (Table 5). Chi square tests confirm similar findings for Ashfield Whites and Fanning's Bostonians, differences being neither significant at 16 (p = 0.849) nor 17 (p = 0.623) years of age. Ashfield 16 year-old Blacks appear to be lagging considerably behind both Hassanali and Chagula groups, but Chagula admits concern that his 16 year-olds may actually have been older. The Chi square test gives p = 0.001 between the Ashfield and Chagula groups to show this lack of association. For the other relationships between Ashfield Black 16 and 17 year-olds and the above comparison groups, Chi square tests do not show discrepancy. Chi square tests show a strong association at age 17 between Ashfield Asians, even though the group is very small, and more third molar eruption compared to Hassanali's Asian sample (p = 0.006). The Chi square test does not show this at age 16 (p = 0.268). 4. Discussion The diverse ethnicity of the Ashfield population allowed comparisons to be made between third molar emergence in different groups. Most third molars were seen in the Black group and a difference between the Black and White groups in the sample at Ashfield has been shown. The Ashfield sample confirms Fanning's [4] finding that extraction of a molar in the same quadrant results in earlier eruption of the third molar and, as Fanning suggested, “non-mutilated dentitions” were identified within the results. Dental practitioners and forensic odontologists in the UK may be interested not only in the ethnic difference revealed in Ashfield population of mainly 16 and 17 year olds, and the fact that three out of the
Table 3 Percentage of 17 year-old YP's third molars present with or without extraction of other molars in the same quadrant. % of M3 present with extraction of other permanent molars in same quadrant
% of M3 present without extraction of other permanent molars in same quadrant
Maxilla 32.1% (9 in 23 quadrants)
Maxilla 24.6% (43 in 175 quadrants)
Mandible 46.4% (13 in 28 quadrants)
Mandible 28.9% (52 in 180 quadrants)
Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
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S.E. Andrews / Science and Justice xxx (2015) xxx–xxx
Table 5 Ashfield and 16 and 17 year-old comparison groups with one or more third molars clinically erupted. White male Fanning, Bostonian Age
% (n)
16 17
22.0 (589) 36.0 (437)
Black male Ashfield, British
Chagula African
Asian male Hassanali Kenyan
Ashfield British
% (n) 20.0 (15) 38.6 (57)
75.0 (62) 76.0 (47)
five Black or Mixed 15 year-olds had at least one erupted third molar; but perhaps also in the common observation of third molars in White individuals. With radiographic assessment, a chronological age may be assigned to these individuals but it seems likely that their age would be overestimated. It has been shown that mandibular third molars erupt between Demirjian stages G and H [32]. According to current practice, if any third molars are observed as emerging in this study, then the individuals could be deemed on the balance of probabilities to be at least 18 years of age [10], as this is the age associated with stage G and H for third molars. This has obvious implications for the carriage of justice. Any scheme devised to estimate age from dental development requires the population providing the reference dataset to be suitable for the individuals to whom it will be applied. Datasets available in the UK to determine age from third molar development at the present time are not population specific. Although ethnic classification has been accepted, migration has caused genetic diversity, the fastest growing ethnicities in the UK are now the mixed groups and, as Harris [8] states, to define a distinct ethnic group is naive. As well as being overrepresented by BME groups, a feature of the young offender population is antisocial behaviour found to be related to high levels of testosterone [34]: a steroid hormone also associated with ethnic variation [35] and suggested to be linked with ADHD [36]. The correlation between third molar eruption and maturational factors such as steroid hormones may warrant further attention. This study has, however, demonstrated ethnic variation in the third molar development and suggests that further work is required to understand population differences and increase the accuracy of dental age assessment. 5. Conclusions 48% of the entire 17 year-old Ashfield group, 68% of the Black and 39% of White 17 year-olds, had one or more clinically erupted third molars. The average age for third molar eruption in Blacks in this study was shown to be less than 18. With radiographic assessment, a chronological age may be assigned to these individuals, but because previous studies show that mandibular third molars erupt between Demirjian stages G and H it seems likely that their age would be overestimated to be at least 18 years of age. Ethnic variation in third molar clinical development between the British Black and White populations at HMP&YOI Ashfield has been demonstrated, illustrating for the first time a difference which is likely to be occurring in the wider population. Radiological assessment will undoubtedly be required to further explore possible ethnic or maturational differences. Acknowledgements I am grateful for the assistance and support of the University of Glamorgan and HMP/YOI Ashfield for making this study possible. References [1] G.J. Roberts, S. Parekh, A. Petrie, V.S. Lucas, Dental age assessment (DAA): a simple method for children and emerging adults, BDJ 204 (2008) E7. [2] L. Brownlees, Z. Yazdani, OCC report: the fact of age: review of case law and authority practice since the supreme court judgement in R(A) v Croydon LBC [2009], Children's Commissioner July 20122012.
Hassanali Kenyan
Ashfield British
% (n) 36.3 (124) 62.0 (92)
14.3 (7) 68.4 (19)
8.2 (49) 22.2 (54)
25.0 (4) 71.4 (7)
[3] W.K. Chagula, The age at eruption of third permanent molars in male East Africans, Am. J. Phys. Anthropol. 18 (1960) 77–82. [4] E. Fanning, Third molar emergence in Bostonians, Am. J. Phys. Anthropol. 20 (1962) 339–345. [5] A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211–227. [6] C.F. Moorrees, E.A. Fanning, E.E. Hunt Jr., Age variation of formation stages for ten permanent teeth, J. Dent. Res. 42 (1963) 1490–1502. [7] J.M. Lewis, D.R. Senn, Dental age estimation using third molar development: a review of principles, methods, and population studies used in the United States, Forensic Sci. Int. 201 (2010) 79–83. [8] E.F. Harris, Mineralization of the mandibular third molar: a study of American blacks and whites, Am. J. Phys. Anthropol. 132 (2007) 98–109. [9] S. Martin-de las Heras, P. Garcia-Fortea, A. Ortega, S. Zodocovich, A. Valenzuela, Third molar development according to chronological age in populations from Spanish and Magrebian origin, Forensic Sci. Int. 174 (2008) 47–53. [10] H.M. Liversidge, P.H. Marsden, Estimating age and the likelihood of having attained 18 years of age using mandibular third molars, Br. Dent. J. 209 (2010) E13 (Published online). [11] G.J. Roberts, V. Lucas, (Letter) Ethical dental age assessment, Br. Dent. J. 207 (2009) 251–254. [12] A. Lewis, S. Garn, The relationship between tooth formation and other maturational factors, Angle Orthod. 30 (1960) 70–77. [13] L. Schour, M. Massler, The development of the human dentition, J. Am. Dent. Assoc. 28 (1941) 1153. [14] S.J. AlQahtani, Atlas of tooth development and eruption, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, 2009. (M Clin Dent and http:/www.atlas.dentistry.qmul.ac.uk). [15] J.C. Mitchell, G.J. Roberts, A.N.A. Donaldson, V.S. Lucas, Dental age assessment (DAA): reference data for British Caucasians at the 16 year threshold, Forensic Sci. Int. 189 (2009) 19–23. [16] J.A. Blankenship, H.H. Mincer, K.M. Anderson, M.A. Woods, E.L. Burton, Third molar development in the estimation of chronologic age in American blacks as compared with whites, J. Forensic Sci. 52 (2007) 428–483. [17] Roberts GJ, Petrie A, − with contributions by Boonpitaksahit T, Parekh S, Percival T, Mitchell J, Yadava M, Donaldson N, Moze K, Lucas VS. (2009) Dental Age Assessment (DAA): of children and emerging adults: a practical guide. Published by Prof Graham Roberts, Dept of Paediatric Dentistry, King’s College Hospital, Bessemer road, London SE5 9RS [18] K.A. Kasper, D. Austin, A.H. Kvanli, T.R. Rios, D.R. Senn, Reliability of third molar development for age estimation in a Texas Hispanic population: a comparison study, J. Forensic Sci. 54 (2009) 651–657. [19] A.B. Acharya, Age estimation in Indians using Demirjian's 8-teeth method, J. Forensic Sci. 56 (2011) 124–127. [20] J. Hassanali, The third permanent molar eruption in Kenyan Africans and Asians, Ann. Hum. Biol. 12 (1985) 517–523. [21] S.A. Odusanya, I.O. Abayomi, Third molar eruption among rural Nigerians, Oral Surg. Oral Med. Oral Pathol. 71 (1991) 151–154. [22] A. Olze, M. Taniguchi, A. Schmeling, B. Zhu, Y. Yamada, H. Maeda, G. Geserick, Comparative study on chronology of third molar mineralization in a Japanese and German population, Legal Med. 5 (2003) S256–S260. [23] A. Olze, A. Schmeling, M. Taniguchi, H. Maeda, P. Niekerk, K. Wernecke, G. Geserick, Forensic age estimation in living subjects: the ethnic factor in wisdom tooth mineralization, Int. J. Legal Med. 118 (2004) 170–173. [24] A. Olze, P. van Niekerk, R. Schulz, A. Schmeling, Studies of the Chronological Course of Wisdom Tooth Eruption in a Black African Population, 2007. [25] A. Olze, T. Ishikawa, B.L. Xhu, R. Schulz, A. Heinecke, H. Maeda, A. Schmeling, Studies of the chronological course of wisdom tooth eruption in a Japanese population, Forensic Sci. Int. 174 (2008) 203–206. [26] A. Olze, B.R. Pynn, A. Schmeling, Dental age estimation in living individuals, Oral Health J. (Can.) (2008). http://www.oralhealthgroup.com/news/dental-age-estimation-in-living-individuals/1000224841/, (Accessed online on 12 March 2015). [27] A. Schmeling, A. Olze, B.R. Pynn, V. Kraul, R. Schulz, A. Heinecke, H. Pfeiffer, Dental age estimation based on third molar eruption in first nations people of Canada, J. Forensic Odontostomatol. 28 (1) (2010) 32–38. [28] P.W. Thevissen, P. Pittayapat, S. Fieuws, G. Willems, Estimating age of majority on third molars developmental stages in young adults from Thailand using a modified scoring technique, J. Forensic Sci. 54 (2009) 428–432. [29] P.W. Thevissen, S. Fieuws, G. Willems, Human third molars development: comparison of 9 country specific populations, Forensic Sci. Int. 201 (2010) 102–105. [30] Immigration Law Practitioners Association (ILPA) information sheet, Age Disputes (Dental X-Rays)2012. [31] R.S. Nanda, Agenesis of the third molar in man, Am. J. Orthod. 40 (1954) 698–706 (abstract only).
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S.E. Andrews / Science and Justice xxx (2015) xxx–xxx [32] G.-Y. Levesque, A. Demirjian, R. Tanguay, Sexual dimorphism in the development, emergence, and agenesis of the mandibular third molar, J. Dent. Res. 60 (1981) 1734–1740. [33] A. Forjani, J. Sarri, M.P. Hector, H.M. Liversidge, The pattern of third molar agenesis, Presented at Pan European Federation of the International Association for Dental Research 2008, 2008 (Available online at http://iadr.confex.com/iadr/pef08/techprogram/ abstract_111423.htm, Accessed on 10 August 2011 and 30 April 2014).
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[34] A. Mazur, A. Booth, Testosterone and dominance in men, Behav. Brain Sci. 21 (1998) 353–397. [35] L. Ellis, H. Nyborg, Racial/ethnic variations in male testosterone levels: a probable contributor to group differences in health, Steroids 57 (2) (1992) 72–75. [36] S.E. Chance, R.T. Brown, J.M. Dabbs Jr., R. Casey, Testosterone, intelligence and behavior disorders in young boys, Personal. Individ. Differ. 28 (2000) 437–445.
Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
Contents lists available at ScienceDirect
Science and Justice journal homepage: www.elsevier.com/locate/scijus
Third molar observations in a sample of British male young offenders Sally E. Andrews Bengough's Lodge, Breadstone, Berkeley, Glos GL13 9 HF, United Kingdom
a r t i c l e
i n f o
Article history: Received 4 May 2014 Received in revised form 22 February 2015 Accepted 25 February 2015 Available online xxxx Keywords: Dental Third molar Development
a b s t r a c t Development, morphology and eruption of third molars are highly variable, and it is generally accepted that the emergence time is between the ages of 17 and 21 years. This study reports on variation in timing encountered in a sample of 155 young males (15–18 years) of British nationality who were detained at Her Majesty's Prison and Young Offenders Institution (HMP&YOI) Ashfield as young offenders. All 155 participants were self-reported in terms of their chronological age and their ethnic origin. Of the 17 year-olds, 68% of Black males displayed one or more erupted third molars compared to 39% of the White males. For those who were of mixed ancestry, 50% showed evidence of eruption of at least one third molar in this age group. This difference between Black and White ethnicity was further supported when missing first or second molars were taken into consideration. Whilst it has been suggested in the literature that ethnicity plays no major part in eruption timings for the third molars, this clinical observation poses some interesting questions about the accuracy of dental age assessment. © 2015 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction Dental age assessment is acknowledged as an important, although not necessarily precise, process for assigning age around the 18 year threshold and is utilised when individuals present without documentation, for example, asylum seekers, disaster victims, forensic and archaeological cases [1]. The accuracy of age assessment can have far reaching implications for those who seek protection under international humanitarian laws and for those who are sentenced under criminal law [2]. Population differences in third molar development had been reported until the early 1960's [3,4] yet interest in this appeared to wane when investigation into tooth development using radiographic methods seemed to take precedence with little attention to ethnicity [5,6]. However, in more recent years, there has been a resurgence of interest reflecting the legal requirement to assign an age to an individual who attempts to enter a country without documentation or who comes to the attention of the courts without possessing the authorised means to confirm their age. Population differences in dental development are being investigated more thoroughly and there is increasing debate surrounding possible ethnic, geographical or social causes and their significance [7,8]. Even though some ethnic differences have been reported in the literature, it has been suggested that geographical or environmental effects may be of greater relevance [9], and some debate as to whether ethnic differences can be substantiated [10,11]. It has also been suggested that steroid hormones could be involved with dental development [8,12].
E-mail address: [email protected].
Based on data from Schour and Massler [13], standard textbooks cite 17–21 years as the standard eruption time for third molars which are the most variable of all human teeth. The atlas approach of pictorial comparison is widely used for dental assessments in individuals under 15 years of age but precision is lost in the older stages of childhood, mainly because all teeth but the third molars have completed their development. More recently, the London Atlas [14] has provided one pictorial representation for each year between 16.5 and 23.5 years of age. Demirjian et al. [5] and Moorrees [6] have established age estimation systems relying on radiographic appearance of developing teeth. These are well-accepted methods and very good correlation between the estimated age and actual age has been reported [15]. Demirjian's method, incorporating the third molar, has been used to evaluate third molars in a number of populations including American Black and White, British, Texas Hispanic and Indian [1,16–19]. Using clinical and radiological methods, studies have confirmed wide age ranges at each third molar stage [3,4,8,16,18–29] and, whilst highlighting the need for more population-specific data, have specifically suggested that ancestry affects the development of third molars. Odusanya and Abayomi [21] studied third molars in 258 Nigerian adolescents and found that the average age at initial clinical eruption was as young as 13 for females and 15 for males. Moreover, all third molars had clinically erupted by age 19 and lower molars erupted before upper molars in both sexes. Harris [8] has highlighted significant ethnic variation in a sample of American Blacks and Whites. Blankenship et al. [16] found third molar developmental stages occurring a year or so earlier in American Blacks compared to Whites, and earlier in males than females. They stated that the likelihood that an African American having fully developed third molars and is at least
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Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
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S.E. Andrews / Science and Justice xxx (2015) xxx–xxx
18 years old is 93%, and 90% for Whites. Using their own and worldwide data, Liversidge and Marsden [10] also calculated the probability of an individual being over or under 18 on the basis of third molar development. They concluded that, for all populations, if the third molar has its apex half or fully complete, age is more than likely to be at least 18 and reported that a single individual from any ethnic group is not significantly different from one in any other group. Demirjian's method for assessment of tooth development requires a radiograph to be taken. As a general rule, radiographs should only be taken to benefit a person's health. There is no therapeutic benefit in taking a radiograph for age estimation and informed consent becomes dubious if a child feels under pressure to agree to a radiograph in order for an asylum claim to be properly dealt with. Considering these two issues together with lack of accuracy in age determination, it has been argued that exposure to radiation would unlawfully inflict harm upon a person [30]. However, Demirjian's method is considered to be one of the most reliable methods to conduct age assessment in children and young adults. As justice hangs on the outcome of the age assessment, it is imperative that it must be accurate in order to justify the exposure to radiation. Without radiographs, forensic odontologists would lose the benefit of Demirjian's methods and would have to be reliant upon clinical eruption of teeth. The likelihood of successful eruption can be improved markedly by removing a molar anterior to a third molar lacking space. Fanning [4] showed that third molars emerge earlier when teeth anterior to them have been removed and pointed out the importance of comparing third molar eruption in “non-mutilated” dentitions. Another factor is agenesis, or failure of formation, which is not an uncommon for third molars but its incidence varies. Chagula [3] quotes studies ranging from as much as 30% in Chinese to 0% in West African Negroes and gives 1.6% in his own study of East Africans. In White American women third molar agenesis has been put at 9% by Nanda [31] and also at 9% in Whites by Levesque et al. [32]. In a study by Forjani et al. [33] of White and Bangladeshi UK citizens, all with third molar agenesis, one missing third molar was found in 45% of the sample, whilst 34% had 2 missing third molars, 6% had 3 missing and 15% had agenesis of all four third molars. The aim of this study was to assess whether there is ethnic variation in third molar emergence by evaluating ethnically diverse young male offenders at HMP&YOI Ashfield. 2. Methods Ethical permission was granted by the University of Glamorgan Ethics Committee and HMP&YOI Ashfield for every young person (YP)
attending the dental unit for treatment to be invited to take part in the study. At the time of the study, HMP&YOI Ashfield accommodated up to 400 males between the ages of 15 and 18 years, representing about 18% of the UK young male offender population. The proportions of ethnic groups in young offenders' institutions (YOI) differ in comparison with the general population. The majority are White, but Black and Minority Ethnic (BME) groups are significantly over-represented compared to the general population. The following data was collected for each individual: date of birth, confirmation of UK citizenship and upbringing, self-assessed ethnicity, any relevant medical history, medication, missing teeth and history of extractions. Third molars were assessed by clinical observation only and data recorded on one single visit. No radiographs were taken for the purposes of this research and therefore it is accepted that missing, unerupted and/or impacted third molars could not be assessed. If not visible, third molars were classified as unerupted. Eruption, or gingival emergence, was defined as penetration of the gingiva by at least one dental cusp. Erupted third molars were further classified as partiallyerupted or, if in occlusion with an opposing tooth, fully-erupted. Participants were asked to self assign to one of fifteen possible ethnic groups (Office of National Statistics classification) and were later assigned by the author to five broader ethnic groups: Asian, Black, White, Mixed or Other. There was a concern that YPs might present with third molar symptoms thereby creating a bias in the sample but this occurred on only one occasion and was not the main presenting complaint. Data was collected from 155 males between the ages of 15 and 18 years. 3. Results The Ashfield sample consisted of 155 British males between 15 and 18 years of age and of diverse ethnicity (Table 1). 88%, were either 16 or 17 years of age, 5% were 15 years of age and 7% had attained 18 years of age. Fifty-six percent of the total sample self-assessed as White, 19% as Black, 17% as being of mixed ethnicities 7% as Asian and 1% gave their ethnicity as “Other”. In total, 83 mandibular and 55 maxillary third molars had emerged. On the left, 27 maxillary and 42 mandibular third molars had emerged (a total of 69 left third molars). On the right, 28 maxillary and 41 mandibular third molars had emerged (a total of 69 right third molars). In the small group of 15 year olds, two of the three Black YPs had erupted third molars and the single mixed ethnicity YP had two partially erupted lower third molars, one in a quadrant where another molar had been lost (Table 2). No third molars were observed in
Table 1 Distribution of ethnic groups in the Ashfield sample of British males. Ethnic group
Age 15
Asian-Indian Asian-Other Asian-Pakistani
Age 16
Age 17
Age 18
Broad ethnic group
Total number (% of total)
1 3 7
Asian
11 (7%)
6 13
9 19 1
Black
29 (19%)
5
Mixed
26 (17%)
1 3
Black-African Black-Caribbean Mixed Black-African/Black-Caribbean
1 2
Mixed Other Black-African/Asian Black-African/Black-African Black-African/Black-Caribbean
1
2 4 1
3 4
4
3 12
6 1 3 16
1
1
2
Other
2 (1%)
11
82 2 1 2
White
87 (56%)
11
155
1
Other
Total number
White-British White-Irish White-Irish traveller White-Other
4
13 1 1
54 1
Total number
8
32
104
2
155
Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
S.E. Andrews / Science and Justice xxx (2015) xxx–xxx Table 2 Number of Ashfield young persons (YP) with erupted third molars (M3), by age and ethnicity. Number of YPs with one or more M3 emerged/total number for that age group and ethnicity
Asian Black Mixed Other White Total
15 year-olds
16 year-olds
17 year-olds
18 year-olds
– 2/3 1/1 – 0/4 3/8
1/4 1/7 2/5 0/1 3/15 7/32
5/7 13/19 10/20 0/1 22/57 50/104
– – – – 3/11 3/11
the four White YPs in this age group. Of the 16 year-olds (n = 32), 14.3% of Black YPs, 40% of the Mixed ethnicity YPs, 25% of the Asian YPs and 20% of White YPs had at least one clinically erupted third molar. For 17 year-olds (n = 104) the small number of Asians had the highest percentage of clinically erupted third molars (71.4%) compared to any other ethnic group at any age; the Black group (68.4%) are also advanced over the White group (38.6%); and the Mixed group (50%) fall between the Black and the White groups. The small group of eleven 18-year-olds were all White and three of those had one or more erupted third molars. As 18 year-olds only stay at Ashfield if their remaining sentence is short, ten of the individuals in this group were aged less than 18 years and 3 months. Of the four major ethnic groupings, the Black 16 year old YPs have the lowest percentage eruption of third molars but by 17 years of age they are almost as high as the Asian group. Those of self-assessed Mixed origin have the highest percentage eruption at 16 years of age and the White teenagers at 17 years have the lowest percentage emergence (Table 2). A Chi square test was applied to investigate statistical association between emergence and ethnic group and a significant difference was only found between 17 year-old Blacks and Whites (p = 0.024). 3.1. Effect of first or second molar extraction Extracted, and therefore missing, first or second molars are a common finding in the Ashfield sample. As first or second molar extraction can affect third molar eruption success, results for percentages of maxillary and mandibular third molars erupted in 17 year-old YPs with and without previous extraction of molars in the same quadrant are shown in Table 3. For example, the chance of a maxillary third molar being present when no other molars in the same quadrant had been removed was 24.6%, or 43 out of a possible 175 cases. 3.2. Comparison of non-mutilated dentitions in Ashfield Black and White ethnic groups The percentage of Black YPs aged 17 without molar extractions and with one or more erupted third molars is 60%. This represents 9 YPs in a group of 15; and 5 of them, or 33%, had all 4 third molars erupted. In comparison, there were 39 White 17 year-olds without molar extractions and 12 of them, or 30.8%, had at least one erupted third molar and 7.7% had 4 erupted third molars.
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Table 4 Table to show 16.75–18.25 year-old White and Black groups and “non-mutilated” third molar (M3) status. Presence of 1 or more
Ashfield
Ashfield
M3 without molar extraction Yes No Chi square = 5.49
White 14 37 Degrees of freedom = 1
Black 10 7 P = 0.019
To further compare the “non-mutilated dentitions” of Ashfield Black and White groups, YPs aged 16.75 years–18.25 years were used (Table 4). This age group was chosen because 10 of the 11 18-yearolds at Ashfield were within this range; and extending the 17 year-old sample by 3 months either side provided a larger sample for this comparison. Having discounted any individuals with missing first or second molars, a sample of 17 Black YPs and 51 White YPs remained. 19.6% of the White and 58.8% of the Black group had clinically erupted third molars in non-mutilated dentitions. The Chi square test shows a strong association (p = 0.019) between ethnicity and erupted third molars at age 16.75 to 18.25 years. The Black group at Ashfield is ahead of the White group. It was also noted that eleven YPs in the Ashfield sample, or 7%, had been diagnosed with attention deficit hyperactivity disorder (ADHD). Eight of these were White 17 year-olds of whom four had at least one erupted third molar. The Ashfield results for percentages of one or more third molars clinically erupted were compared with those from studies by Chagula [3], Fanning [4] and Hassanali [20] (Table 5). Chi square tests confirm similar findings for Ashfield Whites and Fanning's Bostonians, differences being neither significant at 16 (p = 0.849) nor 17 (p = 0.623) years of age. Ashfield 16 year-old Blacks appear to be lagging considerably behind both Hassanali and Chagula groups, but Chagula admits concern that his 16 year-olds may actually have been older. The Chi square test gives p = 0.001 between the Ashfield and Chagula groups to show this lack of association. For the other relationships between Ashfield Black 16 and 17 year-olds and the above comparison groups, Chi square tests do not show discrepancy. Chi square tests show a strong association at age 17 between Ashfield Asians, even though the group is very small, and more third molar eruption compared to Hassanali's Asian sample (p = 0.006). The Chi square test does not show this at age 16 (p = 0.268). 4. Discussion The diverse ethnicity of the Ashfield population allowed comparisons to be made between third molar emergence in different groups. Most third molars were seen in the Black group and a difference between the Black and White groups in the sample at Ashfield has been shown. The Ashfield sample confirms Fanning's [4] finding that extraction of a molar in the same quadrant results in earlier eruption of the third molar and, as Fanning suggested, “non-mutilated dentitions” were identified within the results. Dental practitioners and forensic odontologists in the UK may be interested not only in the ethnic difference revealed in Ashfield population of mainly 16 and 17 year olds, and the fact that three out of the
Table 3 Percentage of 17 year-old YP's third molars present with or without extraction of other molars in the same quadrant. % of M3 present with extraction of other permanent molars in same quadrant
% of M3 present without extraction of other permanent molars in same quadrant
Maxilla 32.1% (9 in 23 quadrants)
Maxilla 24.6% (43 in 175 quadrants)
Mandible 46.4% (13 in 28 quadrants)
Mandible 28.9% (52 in 180 quadrants)
Please cite this article as: S.E. Andrews, Third molar observations in a sample of British male young offenders, Sci. Justice (2015), http://dx.doi.org/ 10.1016/j.scijus.2015.02.005
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S.E. Andrews / Science and Justice xxx (2015) xxx–xxx
Table 5 Ashfield and 16 and 17 year-old comparison groups with one or more third molars clinically erupted. White male Fanning, Bostonian Age
% (n)
16 17
22.0 (589) 36.0 (437)
Black male Ashfield, British
Chagula African
Asian male Hassanali Kenyan
Ashfield British
% (n) 20.0 (15) 38.6 (57)
75.0 (62) 76.0 (47)
five Black or Mixed 15 year-olds had at least one erupted third molar; but perhaps also in the common observation of third molars in White individuals. With radiographic assessment, a chronological age may be assigned to these individuals but it seems likely that their age would be overestimated. It has been shown that mandibular third molars erupt between Demirjian stages G and H [32]. According to current practice, if any third molars are observed as emerging in this study, then the individuals could be deemed on the balance of probabilities to be at least 18 years of age [10], as this is the age associated with stage G and H for third molars. This has obvious implications for the carriage of justice. Any scheme devised to estimate age from dental development requires the population providing the reference dataset to be suitable for the individuals to whom it will be applied. Datasets available in the UK to determine age from third molar development at the present time are not population specific. Although ethnic classification has been accepted, migration has caused genetic diversity, the fastest growing ethnicities in the UK are now the mixed groups and, as Harris [8] states, to define a distinct ethnic group is naive. As well as being overrepresented by BME groups, a feature of the young offender population is antisocial behaviour found to be related to high levels of testosterone [34]: a steroid hormone also associated with ethnic variation [35] and suggested to be linked with ADHD [36]. The correlation between third molar eruption and maturational factors such as steroid hormones may warrant further attention. This study has, however, demonstrated ethnic variation in the third molar development and suggests that further work is required to understand population differences and increase the accuracy of dental age assessment. 5. Conclusions 48% of the entire 17 year-old Ashfield group, 68% of the Black and 39% of White 17 year-olds, had one or more clinically erupted third molars. The average age for third molar eruption in Blacks in this study was shown to be less than 18. With radiographic assessment, a chronological age may be assigned to these individuals, but because previous studies show that mandibular third molars erupt between Demirjian stages G and H it seems likely that their age would be overestimated to be at least 18 years of age. Ethnic variation in third molar clinical development between the British Black and White populations at HMP&YOI Ashfield has been demonstrated, illustrating for the first time a difference which is likely to be occurring in the wider population. Radiological assessment will undoubtedly be required to further explore possible ethnic or maturational differences. Acknowledgements I am grateful for the assistance and support of the University of Glamorgan and HMP/YOI Ashfield for making this study possible. References [1] G.J. Roberts, S. Parekh, A. Petrie, V.S. Lucas, Dental age assessment (DAA): a simple method for children and emerging adults, BDJ 204 (2008) E7. [2] L. Brownlees, Z. Yazdani, OCC report: the fact of age: review of case law and authority practice since the supreme court judgement in R(A) v Croydon LBC [2009], Children's Commissioner July 20122012.
Hassanali Kenyan
Ashfield British
% (n) 36.3 (124) 62.0 (92)
14.3 (7) 68.4 (19)
8.2 (49) 22.2 (54)
25.0 (4) 71.4 (7)
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