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2020 (8)

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Dissertation
Dental Age Estimation Methods Using Development of Third Molars: A Systematic Review
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Year: 2020 Publisher: Leuven KU Leuven. Faculteit Geneeskunde

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Introduction: In forensic context, age estimation in adolescents and young adults is essential to prove whether or not the individual is a minor or an adult. The study aim is to systematically review the literature regarding the age prediction performances of dental age estimation methods based on the development of one or more third molars combined. The set research question is: “What is the most accurate dental age estimation method based on third molar(s) development? Materials and methods: This systematic review was performed according to criteria set forward by PRISMA statement. An electronic search until 03/03/2020 was performed in 4 databases: MEDLINE/PubMed, Cochrane library, EMBASE and Web of Science. Results: 113 studies were considered eligible for inclusion after review of title/abstract, full-text and reference list. Since we only discussed the point prediction and related uncertainty aspect, the age prediction performance and outcomes reported as the error, mean error, mean absolute error, RMSE (root mean squared error), R2 and others were included and classified. The ultimate data extracted for analysis were classified in 3 tables (respectively based on a validation sample): a) mean error (chronological age- estimated age) +- standard deviation, mean absolute error and R*2 number=6, b)regression formula +- standard deviation and R*2 number=11. c) regression model + root mean squared error and R*2 number=5. Discussion: The staging technique turned to be the most accepted registration predictor status compared to others, maybe due to the early origin and many developed branches. And it’s obvious that Demirjian et al. 1973 and Köhler Gleiser and Hunt 1955(modified) outperformed the others. Correspoundingly, the regression formula, linear regression models and Bayesian models were broad used to calculate the estimated ages as age estimation methods. a) The Demirjian et al. method performed better (José 2005) compared to others, especially with low ME(0.07-0.1)+S.D(1.22-1.23), MAE(0.074-0.106) and high R*2(0.45-0.54) and QA score (10) in a large Spanish subadult population. b) The Iranians turned out to have better result in 4TM and 2TM. By the Köhler Gleiser and Hunt 1955(modified) staging technique, they gained a low standard deviation and a high R*2 together with high QA score 9 for the tooth position examined in the study. And in general, the Belgian population performed best in 3TM examined. While for 1 TM, Thais population gained the lowest S.D (M: 1.29-1.3 F: 1.47-1.48) and a extremely high R*2 (M: 0.892 F: 0.85-0.86) using Demirjian technique. c) The Brazilians were found having better scores in RMSE 0.74-1.56 for both genders in linear regression models. Conclusion: In forensic practice, it is difficult to select a method for age estimation based on the development of third molars. In current systematic review, the Demirjian et al.1973(both technique and method)provided the most accurate point prediction of age in Spanish population, Köhler Gleiser and Hunt 1955(modified) technique + regression formula method did the most accurate prediction in Iranians population(4TM and 2TM), Demirjian technique + regression formula outperformed others in Thais population (1TM), and Köhler Gleiser and Hunt 1955(modified) technique + linear regression model method performed best in Brazilians, while more research is needed to verify these methods in the future.

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Dissertation
Evaluation of Cameriere`s tooth development measurements on panoramic radiographs and the effect on related age prediction
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Year: 2020 Publisher: Leuven KU Leuven. Faculteit Geneeskunde

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Among dental age estimation methods in children and sub-adults, Cameriere`s method based on the measurements of open apices is regularly applied in medico-legal cases. The purpose of this study was to investigate the observer reproducibility of Cameriere`s tooth development measurements and classifications and their impact on correlated age predictions. Despite reoccurring reports on a high reproducibility of Cameriere`s measurements, in none of the related publications, a specification and detailed explanation of the gradual steps in the measurement proceedings for the different parameter was provided. Following Cameriere`s protocol, the measurements and classifications on a sample of 237 panoramic radiographs were completely or proportionately performed by 6 observers in 2 replications. The multiple regression model provided in the protocol was used for 1291 subsequent age estimates. For the statistical assessment of intra- and inter-observer agreement on the continuous measurements and the succeeding age estimates, the intraclass correlation coefficients, reproducibility coefficients, as well as the within subject coefficients of variation were determined, while the agreement on dichotomous evaluations of apical ends was analyzed with the Kappa coefficient. In contrast to a good to excellent intra-observer agreement, the inter-observer results for the tooth development measurements revealed an only poor to fair reproducibility for specific tooth positions and caused doubts about the reliability of the resulting age estimates. The partially unspecified protocol of Cameriere was found to have a remarkably negative impact on the inter-observer agreement on the allocations of landmarks and the correlated measurement techniques. Combined with tooth position dependent, impeded diagnostics of the apical ends on panoramic radiographs, this led to a reduced reproducibility of the inter-observer results. Thus, the current study results clearly contradict to the frequently reported good to excellent reproducibility of Cameriere`s measurements in previous studies and gives reasons to consider a specification of the delivered protocol. Suggestions for possible enhancements regarding specific steps in Cameriere`s method are indicated in this study, which encourages the increasement of reliability of age estimations in medico-legal cases.

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Dissertation
Deep learning based age estimation from whole panoramic dental images
Authors: --- --- ---
Year: 2020 Publisher: Leuven KU Leuven. Faculteit Ingenieurswetenschappen

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Age is an important feature of a person. Sometimes this information is not available. This is possible when you deal with migration. Because The official documentation is not available. Or a corpse where there is no identification available. In this case, a method is needed to determine the age. There exist methods to determine the age based on teeth information. However, these method’s rely on manual staging of the teeth which is time consuming. In this thesis, an automatic approach is researched to determine the age of a person. In this approach, you try to predict the age based on dental X-ray images. The proposed method tries to solve this problem using convolutional neural networks. This neural network is trained on a dataset of 4000 pictures of people between the ages of 8 and 25 year. The thesis focuses on preprocessing the data, selecting the best possible neural net architecture and finetuning the hyperparameters to get the best result possible. In the end, the proposed method was evaluated using 5-fold cross validation. The result is an MAE is 089 years and the MSE is 1.45 years. These results are very competitive towards the already available methods.

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Dissertation
Automated staging of the developing lower left second molar using a convolutional neural network
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Year: 2020 Publisher: Leuven KU Leuven. Faculteit Geneeskunde

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In the path to create a fully automated dental age estimation method for use on young individuals, automated staging techniques using deep convoluted neural networks have been studied; though promising great value in forensics, research in this topic has been restricted to only automatically stage the developing lower left third molar. To be applicable to children who have not yet acquired these teeth or whose third molars are in very early stages, classifying the remaining lower left permanent teeth is necessary. The developing lower left permanent second molar will be the first tooth evaluated for establishing automated staging techniques in individuals under 16 years. This study aimed to compare automated stage allocation performance of tooth 37 (Federation Dentaire Internationale Numbering) with that of tooth 38. It additionally aimed to determine the best model that could correctly allocate tooth development stages of the 37 and the 38. To accomplish this, 358 panoramic radiographs were established as the training set for tooth 37 by agreement in staging between three observers. This gold standard, consisting of up to 20 bounding box radiographic images of 37 for each stage and each sex, were imported to the DenseNet201 neural network. Second molar images of stages 0 to A in the modified Demirjian technique used were limited, preventing uniform distribution of stages. The gold standard for the lower left third molar prepared in a previous study were imported separately to the same neural network. That software was trained to recognize and classify developing 37 teeth, retrained to do the same for developing 38 teeth, and then the performance of automated predictions for stages of 37 and 38 were assessed. The overall performance of the automated staging of the lower left permanent second molar (measured as mean accuracy, Cohen Kappa, and mean absolute error) is much better than that of the lower left third molar in this study and in the pilot study[1]. Tooth 37 predicted in the 37 Model, with the best overall performance, had a Cohen Kappa of 0.923, a mean accuracy of 77% and a mean absolute error of 0.238; prediction of 37 stages was comparatively worse with the 38 Model . The stage allocation performance of 38 was “more worse” with the 37 model than with the 38 model; with the 37 model, it also had the worst overall performance; the Cohen Kappa was 0.600, the mean accuracy was 0.435 and the mean absolute error was 1.129. The 37 model predicts the 37 with comparably high reproducibility as attained in manual staging of 38. Future research will examine stage allocation performance using other models and, thereafter, investigate the prediction of stages of other developing permanent teeth.

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Dissertation
Unique Tooth Dimensions on Panoramic Radiographs for Human Identification Purposes
Authors: --- ---
Year: 2020 Publisher: Leuven KU Leuven. Faculteit Geneeskunde

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Dental identification relies on comparing dental treatment features, odontogenic morphological features or a combination of both. Treatment features are usually the first line of assessment used. However, factors such as incomplete dental records, ongoing decline in number of dental restorations has made morphological features become more important. There is at the moment, no conclusive evidence that the human dentition is indeed unique, which is the basis in being able to use morphological features for identification. The aim of this study is to identify unique tooth dimensions on panoramic radiograph for human identification purposes. Sixty-two digital panoramic radiograph from 31 females and 31 males (age ranged from 13 to 56 years old) were collected retrospectively from a private dental clinic in Belgium. Six tooth measurements were performed on all seven mandibular left permanent teeth (excluding third molars): tooth length (TL), crown length (CL), root length (RL), crown width (CW), cervical width (CEJW) and root width (RW). 9 length-width ratios were then calculated using these measurements: CL/CW, CL/CEJW, CL/RW, RL/CW, RL/CEJW, RL/RW, TL/CW, TL/CEJW, TL/RW. Analyses for the ratios were based on log-transformed values. Intra and inter observer reliabilities for each parameter were assessed in terms of intra-class correlation (ICC), standard error of measurement (SEM) and reproducibility coefficient (RC). Sex differences in measurements/ratios per tooth position were evaluated using two-way linear models and correlations between measurements/ratios per tooth position were verified with Spearman correlations. Univariate and multivariate analyses were performed to calculate ‘potential set’ for an indication of uniqueness. Combining all measurements for tooth 31 produced the lowest potential set, which indicates the most unique tooth for identification purposes. Compared to single parameters, combining measurements or ratios substantially improve the mean potential set.

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Dissertation
Identificatie-accuraatheid van dentale patiëntendossiers in de Vlaamse tandartspraktijk: een vergelijking van de klinische patiënttoestand met haar/zijn geregistreerde dossiergegevens
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Year: 2020 Publisher: Leuven KU Leuven. Faculteit Geneeskunde

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In deze scriptie wordt de accuraatheid van dentale gegevens in tandheelkundige dossiers in de Vlaamse tandartspraktijk nagegaan. De resultaten werden besproken met zicht op betrouwbaarheid van deze dossiers als bronnen voor de identificatie van slachtoffers. Het onderzoek bestaat uit een vergelijking van dentale informatie, zoals die in de dossierafschriften staat, met de werkelijke mondsituaties van de studiepersonen. Om de vergelijkingen van 45 afschriften op een eenduidige manier te laten verlopen is gebruik gemaakt van de Disaster Victim Identification (DVI) methode van Interpol. Samengevatte resultaten: - Het occlusiepatroon is zelden beschreven (slechts bij 6 van de 45 dossierafschriften); - Zonder OPG of dentaal schematisch overzicht is een beschrijving van de aanwezigheidsstatus van tandelementen minder accuraat; - Slechts 24 (van de 50) aanwezige retentiedraden werden correct beschreven, de aanwezigheid van radiologische beeldvorming in het afschrift had geen significante invloed hierop; - Informatie over glazuuraandoeningen en zeker afwijkingen in de tandpositie is onvoldoende genoteerd om hier te veel waarde aan te hechten in het kader van identificatie; - Uitgevoerde conserverende behandelingen en hun lokalisatie op de tand werden met respectievelijk 92,30% en 93, 75% accuraatheid beschreven; - Enkele (mogelijke) inbreuken tegen de Belgische wetgeving werden vastgesteld wat betreft de inhoud van de patiëntendossiers. - Zorgvuldige analyse van dossierafschriften is nodig om misinformatie uit te sluiten.

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Dissertation
Morphometric uniqueness of measurements between mandibular landmarks on panoramic radiographs for human identification
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Year: 2020 Publisher: Leuven KU Leuven. Faculteit Geneeskunde

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Background During human identification, forensic experts often encounter decomposed and fragmentary human remains. Poorly preserved bodies, as well as fragmented remains, limit considerably the methods used for identification and significantly increase the complexity of the identification procedures. Aim The aim of the current study is to register and evaluate measurements between mandibular landmarks and to quantify their uniqueness and their potential for identification of human remains. Materials and methods One hundred eighty-five digital panoramic radiographs (94 males and 91 females; age range 16-66 years) were retrospectively collected from the dental clinic files of the Audacia Dental Clinic, Brussels, Belgium, and imported in image enhancement software. Fourty-one parameters were measured (5 linear, 6 angles and 10 ratios) on both sides of the mandible. Univariate and multivariate analyses were performed to quantify the potential for identification of each parameter and their combinations. Results Measurements E and R 3 proved to be the most useful in identification. The best identifying measurement combination uses all the ratios parameters. Discussions and Conclusions The method described in this study allows for human identification by narrowing the AM search field based on the available PM panoramic radiograph.

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Dissertation
Comparison of tooth development staging in Panoramic and Cone Beam Computed Tomography (CBCT)

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in forensic odontology various age estimation methods and technique were published but there’s a lack in the Comparison of tooth development staging in Panoramic and Cone Beam Computed Tomography (CBCT) using Demirjian and kohler staging techniques in third molars. Retrospectively 420 patients were collected from the KU Leuven hospital. Patients with any development disorder, missing third molars or not having the CBCT and the Panoramic taken of the same date were excluded from the study. Panoramic and CBCT viewed by the Synedra view personal.

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