Publications by authors named "H M Liversidge"

50 Publications

Status of Mandibular Third Molar Development as Evidence in Legal Age Threshold Cases.

J Forensic Sci 2019 May 8;64(3):680-697. Epub 2018 Oct 8.

Institute of Dentistry, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AD, U.K.

The completion of the third molar roots has played an important role in ascertaining whether individuals may be at or over a legal threshold of age, often taken as 18 years. This study demonstrates that root apex completion in the third molar is relatively uninformative regarding the threshold of age 18 years in a sample of 1184 males, where mean age-of-attainment of root apex completion for third mandibular molars is about 19.4 years. This paper also considers the legal age threshold problem for cases where the third mandibular molar is not completely formed, and outlines the use of parametric models and Bayes' factors to evaluate dental evidence in statistically appropriate ways. It attempts to resolve confusion over age-within-stage versus age-of-attainment, likelihood ratios versus other diagnostic tests, and prior odds for a case versus the prior density for an age distribution.
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http://dx.doi.org/10.1111/1556-4029.13926DOI Listing
May 2019

A Reappraisal of Developing Deciduous Tooth Length as an Estimate of Age in Human Immature Skeletal Remains.

J Forensic Sci 2019 Mar 20;64(2):385-392. Epub 2018 Aug 20.

Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Institute of Dentistry, Turner Street, London, E1 2AD, U.K.

This study provides an update on a quantitative method for immature age estimation based on postnatal deciduous mandibular tooth length. Two known sex and age skeletal collections from Western Europe were sampled (n = 97). Linear regression models for age estimated were calculated for each individual tooth, each sex, and sex combined sample using classical calibration. Prediction errors, residuals, and percentage of individuals whose real age fell within the 95% prediction interval were calculated. The teeth which develop earlier in life, the incisors and the first molar, showed the greatest precision, while the canine showed the least. This method has greater applicability to archeological skeletons or to children in developing countries than for use in North American or European forensic contexts. The method can be applied to incomplete or poorly preserved remains of unknown sex, particularly when dental radiographs are not an option or when teeth have been removed from the alveolus or crypt.
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http://dx.doi.org/10.1111/1556-4029.13892DOI Listing
March 2019

Estimating age using permanent molars and third cervical vertebrae shape with a novel semi-automated method.

J Forensic Leg Med 2018 Aug 27;58:140-144. Epub 2018 Jun 27.

Institute of Dentistry, Queen Mary University of London, UK.

Estimating chronological age accurately in young adults is difficult and additional methods are required to increase the accuracy. This study explored a new semi-automated method to assess shape change of third cervical vertebra (C3) with age in the living; comparing this as a method to determine whether individuals could be categorised into being less than 18 years of age (<18), or at least 18 years of age (≥18) with tooth formation of the second and third mandibular molars (M2 and M3). The sample was panoramic and lateral skull radiographs of 174 dental patients (78 males, 96 females aged 15-22 years). Twelve variables were compared in two age categories: younger than 18 and at least 18 years of age in males and females separately using a t-test. Tooth formation of M2 and M3 was assessed. Mean values of eight variables of C3 in males and one variable in females were significantly different between the two age categories (p < 0.05). Results for males showed that the best age indicator for age ≥18 was the ratio between height and width of C3 and for females, the ratio between diagonals. Results for molars showed that M2 was mature in 69% of males and 83% of females, within the expected age range of 14-16 years. M3 was highly variable ranging from stages 6-14 for both; M3 was missing in 24% of males and 28% of females and mature in 14% of males and 15% of females. The conclusion was that shape change of C3 has potential as an additional method to group individuals <18 and ≥ 18 years of age.
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http://dx.doi.org/10.1016/j.jflm.2018.05.010DOI Listing
August 2018

Response to Comment on "The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain)".

Science 2018 03;359(6380)

Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK.

The comment by DeSilva challenges our suggestion that brain growth of the El Sidrón J1 Neandertal was still incomplete at 7.7 years of age. Evidence suggests that endocranial volume is likely to represent less than 90% adult size at El Sidrón as well as Neandertal male plus Krapina samples, in line with further evidence from endocranial surface histology and dural sinus groove size.
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http://dx.doi.org/10.1126/science.aar3820DOI Listing
March 2018

A radiographic study of the mandibular third molar root development in different ethnic groups.

J Forensic Odontostomatol 2017 Dec 1;35(2):97-108. Epub 2017 Dec 1.

Institute of Clinical Dentistry, University of Oslo, Oslo, Norway.

Background: The nature of differences in the timing of tooth formation between ethnic groups is important when estimating age.

Aim: To calculate age of transition of the mandibular third (M3) molar tooth stages from archived dental radiographs from sub-Saharan Africa, Malaysia, Japan and two groups from London UK (Whites and Bangladeshi).

Materials And Methods: The number of radiographs was 4555 (2028 males, 2527 females) with an age range 10-25 years. The left M3 was staged into Moorrees stages. A probit model was fitted to calculate mean ages for transitions between stages for males and females and each ethnic group separately. The estimated age distributions given each M3 stage was calculated. To assess differences in timing of M3 between ethnic groups, three models were proposed: a separate model for each ethnic group, a joint model and a third model combining some aspects across groups. The best model fit was tested using Bayesian and Akaikes information criteria (BIC and AIC) and log likelihood ratio test.

Results: Differences in mean ages of M3 root stages were found between ethnic groups, however all groups showed large standard deviation values. The AIC and log likelihood ratio test indicated that a separate model for each ethnic group was best. Small differences were also noted between timing of M3 between males and females, with the exception of the Malaysian group. These findings suggests that features of a reference data set (wide age range and uniform age distribution) and a Bayesian statistical approach are more important than population specific convenience samples to estimate age of an individual using M3.

Conclusion: Some group differences were evident in M3 timing, however, this has some impact on the confidence interval of estimated age in females and little impact in males because of the large variation in age.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6100223PMC
December 2017