Non-destructive dental-age calculation methods in adults: intra- and inter-observer effects
Introduction
Estimation of age in individuals has received considerable attention in the forensic scientific literature as well as in archaeological cases. Some age estimates are based on the degree of closure of the sutures and epiphyseal plates [1], others on the degree of dental attrition [2], [3]. Many other techniques have been reported but scientific statistical methods or specific dental methods are rarely used. However, forensic odontologists have a number of such methods available for use in their discipline. The search for optimal age estimation procedures has continued over the years until the present day. Age estimation in individuals, dead or alive, will continue to be of tremendous importance in various circumstances such as in the case of adult refugees.
Several techniques are available for dental-age estimation in children and because of the presence of a multitude of developing teeth, the accuracy of dental-age estimation in children is much greater (standard error (S.E.) ±1–2 years) [4], [5], [6], [7] compared to adults (S.E. ±10 years) [8]. Basically, two main groups of well-known techniques based on dental maturation are available for this purpose, the atlas-techniques [4], [5], [6] and the scoring-techniques [7], [9].
The same techniques may be applied in estimating the age in disaster victims. Any dental examination of a deceased person whose identity is unknown should include an estimation of age. In cases where there is no indication of the identity, age estimation may be crucially important for the progress of the investigation. It narrows down the search within the missing persons’ files and enables a more efficient approach.
For adults, the literature offers different possibilities, such as morphological [10], [11], [12], [13], [14], [15] and radiological techniques [16], [17]. Among these techniques are very fine and relatively accurate methods that nowadays are available for forensic odontologists [18]. Some of these methods do not require grinding or sectioning of teeth and as such do not cause destruction of tooth substance. This may be important since the forensic odontologist does not always have permission to produce tooth sections in order to make an age estimation. Clearly tooth sectioning is not appropriate for living adults. Especially when determining the criminal responsibility of a young adult, the individual’s chronological age might be out of the age range of the techniques developed for children. Non-destructive techniques for adults could then be used. As a first step, the experienced forensic odontologist should perform a visual age estimation of the tooth, teeth or dentition to be evaluated. This seemingly unscientific approach has shown to be of value in dental-age estimation, especially after obtaining conflicting and contradictory results when using different techniques [8]. The visual age estimation should be complemented by at least one other and preferably more age estimation techniques. In living individuals, only radiological techniques [16], [17] may complement the visual age estimation. For deceased persons where no permission was granted for tooth sectioning, both the radiological age estimation techniques mentioned and an age estimation based on the length of the translucent zone of the tooth apex [12] are techniques that can be used in addition to visual age estimation. All these techniques are well described in the literature and offer the advantage of non-destructive age evaluation. However, questions may be raised concerning their reliability and reproducibility and whether non-experienced dentists are able to produce age estimation as accurate as their experienced colleagues.
The purpose of this study was to evaluate the inter- and intra-observer effects on two non-destructive age estimation methods in adults, one morphological [12] and one radiological [17] in order to obtain data on the reliability and reproducibility of these techniques.
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Materials and methods
Anterior teeth and bicuspids from Belgian Caucasian origin, scheduled for extraction, were collected in the University Hospital St. Raphael (Katholieke Universiteit Leuven, Leuven, Belgium) and the University Hospital of Antwerp (University of Antwerp, Antwerp, Belgium). Each extracted tooth was stored separately in a plastic container filled with an aqueous solution of chloramine 0.5%.
The dentists who performed the extractions were given instructions on how to code the containers. They made
Results
The results of the statistical analysis of the age estimations are displayed in Table 1, Table 2, Table 3, Table 4. The P-values for the morphological method [12] are listed in Table 1. No significant differences were found between the real age of the tooth and the estimated age. This was true for both examiners A and B. On the other hand, intra-observer evaluation for examiner B showed a significant difference between the two measurements (B1 versus B2, Table 1). Inter-observer evaluation
Discussion
In some studies, the extracted teeth have been stored in tap water at room temperature for up to 6 weeks or more, without disinfection or sterilization [20]. Pulp tissue and components of dentin may be degraded and bacteria may alter the pulpo–dental complex. The same applies to teeth stored in physiological saline solution [21].
In order to avoid infection and preserve tooth structure, teeth have been stored either in buffered 10% formalin [22], [23] or in a 70% alcohol solution [24] for
Conclusion
Two techniques for non-destructive age estimation described in literature have been compared in this pilot study. The morphological technique [12] resulted in accurate dental-age estimation regardless of the experience of the forensic odontologist. The radiological technique makes accurate age estimations possible in living adults, at least when the original protocol is carefully followed. This necessitates the use of a stereomicroscope. Further research is needed to evaluate whether the
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