A review of the methodological aspects of aspartic acid racemization analysis for use in forensic science.

Accurate age determination of adult cadavers and human remains is a key requirement in forensic practice. The current morphological methods lack accuracy and precision, require specialist training and are costly. The use of aspartic acid racemization (AAR) in human dentine provides a simple, cost-effective solution and the method can achieve accuracies of +/- 3 years at best. Currently, there are differences in AAR methodology between laboratories which produce different results on the rate of racemization in teeth. These inconsistencies must be resolved if the technique is to be successfully applied to age determinations in forensic cases. This paper reviews the differences in protocol which have been used, discusses how each method will affect the results obtained from AAR analysis and gives recommendations for optimization of the methological protocol as a first step towards international standardization.

Accuracy in establishing identity by means of intraoral radiographs.

The aim of this study was to evaluate the accuracy in establishing identity of individuals by means of different dental characteristics observed in "ante- and postmortem" bitewing radiographs. Three categories of individuals, based on dental therapy conditions, were considered: Group A) no therapy, Group B) simple therapy, and Group C) complicated therapy. Seven examiners were asked to combine "ante- and postmortem" radiographs and all reports were made on standard forms. The results show that all observers were able to determine identity for the cases in the simple therapy group. In contrast, three observers presented incorrect answers on two cases each in the nontherapy group. Further, two observers were unable correctly to determine identity for four cases in the complicated therapy group. Among a total of seven observers only two observers made no mistakes in any of the groups.

Denture marking. A study of temperature resistance of different metal bands for ID-marking.

Dentures are not always marked. In Sweden legislation now exists to enforce it. This study was undertaken to establish the frequency of marked dentures, the incidence of edentulousness and a temperature resistance test of three possible marking bands. Patients from two long-term units were included in the study (n = 58). Observation of the dental status included absence of teeth, some teeth present and influence of dentures, complete, partial, upper or lower. Marking of the dentures was also recorded. Three different types of steel bands (Jasch; Remanit; ID-band) were exposed to temperature levels of 1100, 1200 and 1300 degrees C. Of a total of 58 patients 64% were edentulous and only 17 of the patients could be identified by means of the denture markings. None of the metal bands had readable markings at 1200 and 1300 degrees C, but at 1100 degrees C the ID-band and the Jasch band were readable, but not the Remanit band.

Accuracy among dentists experienced in forensic odontology in establishing identity.

The aim of this study was to investigate the accuracy of 17 forensic odontologists identifying individuals from two sets of radiographs, one regarded as ante- and the other as postmortem. Each case was observed twice and only one pair out of 31 did not match. The observers were asked to comment about each case, classifying it as easy, moderate or difficult. The results show that one observer was totally correct in the first analysis while four observers made no errors the second time. In the first evaluation 14 observers made between one and seven errors and two observers made 11 errors each. In the second evaluation 12 observers made between one and seven errors and one observer made 13 errors. At the first evaluation, the observers judged 18 of the cases as easy, eight as medium and five as difficult. At the second evaluation, the observers pronounced 13 of the cases as easy, 13 as medium and five as difficult. The corresponding values for the authors were 6, 12 and 13. Most of the mistakes were made on the cases with no restorations and the incorrect answers were found mostly among the difficult cases. In practical forensic work however additional dental chart information is usually available to the forensic odontologist.

Accuracy in establishing identity in edentulous individuals by means of intraoral radiographs.

The aim of this study was to evaluate the degree of accuracy in establishing identity in edentulous individuals by using occlusal "ante- and postmortem" radiographs of the maxilla. Twelve examiners with the following background; six dental radiologists, four other specialists in dentistry and two dental students were asked to combine the radiographs. The results showed that six of the 12 observers were able to correctly establish identity for all 20 cases. Five of these observers were dental radiologists and one of them was a prosthodontist. The other specialists made 3-8 identifications. The senior and the junior dental students made two and four incorrect identifications. The findings from this study emphasise the importance of having more than one forensic specialist signing the identification form. The results also indicate that examiners well trained in oral radiology are able to determine a positive identity even in cases where the teeth are not present.

Accuracy of dental registrations in forensic odontology among dental students.

The registration of dental characteristics in forensic work is crucial to the identification procedure and because of this, standardised recordings of dental characteristics should be applied. In order to improve accuracy in identification it is important to evaluate the types of errors that are made during the different steps of the procedure. Attempting to identify the most common interindividual variations, twelve dental students made recordings on excised, macerated jaws at the Department of Forensic Medicine in Göteborg as a part of the course in Forensic Odontology. The most common error was incorrect judgement of the extent of single restorations. Furthermore, the students had difficulty in identifying premolars and molars, especially in the mandible, confusing the two groups of teeth. This study emphasises the importance of carefully re-examining the postmortem dental findings by an experienced forensic odontologist before comparing them with the antemortem data.

Dental condition and identification marking of dentures in homes for the elderly in Göteborg, Sweden.

Denture marking is of crucial importance especially in homes for the elderly where dentures could be misplaced, particularly during cleaning by staff where there is a chance of loss or mix-up. Recent research regarding denture marking in homes for the elderly shows that only about 50% of the dentures were marked and that the issue should receive attention. The aim of this study was to investigate the number of subjects with natural teeth and the number of edentulous subjects in homes for the elderly in Göteborg, Sweden. The results of the present work show that only about 35% of the complete dentures were ID-marked. Thus, even if the number of complete denture wearers is few, in Sweden presently there are predictions that dentures will become more common in the future, and also in other parts of the world owing to the socio-economic conditions of today and likely in the future.

Accuracy of dental registrations in forensic odontology among dentists and dental students.

In forensic odontology, registration of dental characteristics is crucial in the identification procedure. It has been found that the most common errors made are incorrect registration of restorations and confusion about premolars and molars in both jaws. In an earlier study, dental students were observers and the charting was made without radiographs. However, in practical forensic work dentists make the registrations and radiographs are usually available. In this investigation eight dental students and eight dentists made registrations on ten excised macerated jaws with the aid of radiographs. The mean number of errors for each jaw for the students and the dentist was 4 and 3 respectively. The most common error among the dentists was incorrect registration of restorations, while errors on registrations of missing teeth were most common among the students. Even though the material in this study was limited, the results indicate the importance of re-examining of postmortem findings before the comparison with the antemortem data is done. Additionally, the forensic work should be performed by specialists.

Accuracy in identification of implant treated patients by use of intraoral radiographs.

This study aimed at investigating the accuracy of seven forensic odontologists (FO) and seven police officers (PO) in determining person identity using comparable intraoral radiographs from implant treated patients, and evaluating the different characteristics used for identification. The investigation was based on 34 edentulous patients, from 26 of whom a matched pair of radiographs was constructed in such a way that one, taken after insertion of an implant supported prosthesis in the anterior part of the mandible, was regarded as the antemortem radiograph, while another picture from a later follow-up examination served as the postmortem x-ray. From each of the remaining eight patients similar radiographs were selected so that four antemortem and four postmortem ones were obtained. These eight radiographs were also paired but did not match. There were thus 30 pairs of radiographs. A classification of the 26 matched pairs regarding degree of ease (easy, moderate, difficult) in combining the radiographs, using as parameters the design of the implants, shape of the abutments, shape of the bridges and bony anatomy of the jaws was established. The total number of errors made by the FO were higher (26) than those made by the PO (18) (one PO combined all 26 matching radiographs correctly) and 12 of the 26 matchable cases were correctly paired by all observers. The design of the fixed prostheses was the most often used characteristic in the exercise.

Denture marking. Clinical and technical aspects.

The frequency of edentulousness has decreased in recent years due to the improvement in oral health. However, there is still a need to address the issue of denture marking for social and legal reasons because the oral status of populations varies in different countries and the wearing of complete dentures will be a fact for the foreseeable future. Given that only one marked denture can tell us the identity of a decreased when all other methods fail makes it a worthwhile exercise. The marking of dentures is not regulated by law in Sweden, but it is recommended by the Swedish Board of Health and Welfare (SOSFS[M]1986), that all patients should be offered the opportunity to have their dentures marked, which they may refuse. In Sweden, the dental laboratories report that they mark all dentures. The Swedish ID-Band has become the international standard and FDI accepted denture marking system, but recent research has indicated that this metal band is not resistant to very high temperatures. Since there is no international consensus regarding the matter we suggest that new materials should be explored.

On denture marking.

During the last decades in Sweden dentures have been permanently marked with a stainless steel metal band incorporated into the acrylic and containing the patient's birth date, a special number, and "S" for Sweden. The last recommendation issued by the National Board of Health and Welfare states that "the patients shall always be offered denture marking and be informed about the benefit thereof. Denture marking is not permitted if the patient refuses it". Requirements for denture markers have been that they should be biologically inert (when incorporated into the denture), not be expensive, be easy to inscribe, be possible to retrieve after an accident, and survive elevated temperatures for a reasonable time under normal circumstances. Although the frequency of edentulousness has decreased in recent years due to the improvement in oral health there remains a need to address the issue of marking of complete dentures, because there is a large variation in the oral status of populations in different countries. Given that only one marked denture can reveal the identity of a deceased person when all other methods fail to do so, makes it worthwhile. Furthermore, denture marking is important in long-term care facilities. We have investigated the issue of denture marking in Europe and in the United States. The results from the European survey show that denture marking is, to our knowledge regulated by law only in Sweden and Iceland. In the US denture marking is so far mandatory in 21 states while New York State requires dentures to be marked if the patient requests it and several other states impose the obligation to mark dentures on long-term care facilities. Since there is no international consensus regarding the issue of denture marking it is important to address it. A survey from the Nordic countries has shown that if denture marking was in general use, the contribution to the establishment of identity by forensic odontology in cases of fire would increase by about 10%. This means that about 25 more individuals could have been identified if their dentures were marked. Increased international collaboration is needed to solve the issue of denture marking for clinical and forensic purposes.

The lateral periodontal cyst. A histopathological and radiographic study of 32 cases.

The lateral periodontal cyst is a developmental odontogenic cyst usually found in the premolar area of the lower jaw. The clinical, radiographic and histopathological features of 32 previously unreported lateral periodontal cysts were reviewed. In four cases the follow-up, which extended over several years, was also studied. Different theories of pathogenesis are discussed.

Odontogenic myxoma--a radiographic study of 21 tumours.

Radiological features of 21 odontogenic myxomas found in 14 women and 7 men were analysed. Ten of the tumors were unilocular and 11 were multilocular. Unilocular lesions were mostly located in the anterior and multilocular in the posterior areas of the jaws. Intralesional trabeculation was seen in all multilocular but only in 3 unilocular lesions. Because radiological appearance of myxoma may be essentially similar with many other lesions of the jaws careful radiological examination is mandatory for planning of proper treatment.

Mandibular condyle morphology in relation to malocclusions in children.

Recent studies show that forces applied to the mandible during treatment with functional appliances and other orthodontic therapies produce changes in the TMJ. Specific malocclusions might also apply forces that can produce changes in the morphology of the TMJ. This study examined 104 orthodontic patients (44 males and 60 females) prior to treatment. The size and location of the condyle was determined on submento-vertex and tomographic films which was related to clinical findings including age, sex, malocclusion type, facial type, TMJ symptoms, tooth eruption sequence, crossbites and midline discrepancies. The medio-lateral width of the condylar head correlated positively with the patients age (p less than 0.001) and sex (p less than 0.001). Also the antero-posterior widths of the condyle were correlated with age (p less than 0.05). The condylar size in males was found to be greater than in females. Midline discrepancy significantly altered the increase in condylar size during growth. Transversel anomalies had a markedly greater influence on condylar growth compared to other characteristics of occlusion. The major change in condylar size during growth occurred in medio-lateral dimension as compared to the antero-posterior. In addition, the medio-lateral width was affected by midline discrepancy but not the antero-posterior width.

The paradental cyst a clinicopathologic study of 26 cases.

This retrospective study describes the clinical, radiographic and histological features of 26 paradental cysts. These cysts comprised 0.9% of the 2700 cases of jaw cysts diagnosed in 9 years. The true incidence is, however, probably greater since many cases are misdiagnosed. The cysts occurred in relation to partly or fully erupted teeth and were all located in the mandible. An equal sex distribution was found and clinical symptoms in the form of swelling was the main finding especially for the paradental cysts located in the first and second molar area. The radiographic characteristics of the paradental cysts were found to be rather variable. The borders of the cysts adjacent and distal to the third molars were more distinct than the borders of the cysts in the first and second molar area. Histologically, all the cysts were lined by a nonkeratinized stratified squamous epithelium with edema and migration of neutrophils through the epithelium. In most cases, the epithelium was markedly hyperplastic. The connective tissue wall was infiltrated by neutrophils, lymphocytes and plasma cells.

27 years of forensic odontology in Göteborg, Sweden.

The aim of this study was to analyze retrospectively all cases of forensic odontology during the period 1964-1990 in Göteborg. A total number of 281 cases were registered during a period of 27 years. The mean age of the victims was 39.5 years and 73 per cent of the deceased persons were men. The identification cases dominated (274). A definitive identity was established in 207 cases (75.6%) and the identity could not be determined in 34 cases (12.4%). The causes of death were also analyzed. The total number of burned victims; in buildings, boats or cars was 84. Eighty-one persons were submersed in water. There were 49 victims of mutilation due to traffic accidents. Twenty-two persons were found in the wood. Seventeen persons died in their homes or abroad and were not found immediately after death and therefore the relatives were not asked to identify the decreased. There was no information about the cause of death in 21 cases.

Knowledge among Swedish dentists about rules for patient records.

Some Swedish dentists chosen at random answered a questionnaire in 1992. The aim was to find out if the knowledge among dentists as a whole about patient record matters is as bad as patient records in disciplinary cases imply. The knowledge was good and better than expected. Specialists have a better knowledge than private practitioners and they also more often have a secretary to handle the patient records. Time of licensation and the dentist's age were of no importance. If the standard of knowledge in a few formal matters corresponds to a high standard in the observance of the rules will be investigated in the second part of this investigation (Rasmusson et al 1994), which will scrutinize patient records from the same dentists who answered the questionnaire.

Quality evaluation of patient records in Swedish dental care.

The purposes of this study were to evaluate systematically five patient records each from randomly selected dentists in different regions of Sweden in 1992, and to see whether the good knowledge of some record-keeping rules, noted earlier, was reflected in practical observance of the rules as a whole. Observance was generally poor: in nearly 40% of the variables investigated, the documentation did not follow the rules. Patient history, status, diagnosis, therapy plans and other important information were often missing among the records from the general practitioners. The specialists' records, however, were in general very accurate. As a whole, Swedish dental patient records constitute poor antemortem material for forensic odontology. The dentist's age is related to the quality of the records. The standard of the patient records must be improved.

Tooth wear and temporomandibular joint morphology in a skull material from the 17th century.

Skeletal remnants from the skulls of 69 subjects from the 17th century have been studied focusing on TMJ morphology and tooth wear. Several of the skulls were damaged and altogether 68 condyles and 28 temporal components of the TMJ, and 97 dentate jaws could be examined. Tooth wear was extensive and most of the first molars in both jaws had lost most of their occlusal morphology. This is remarkable with respect to the fact that the great majority of the subjects had died before the age of 35 years, according to the age determination performed. The TMJs showed frequent remodelling but only rarely deformative changes. The frequent observation of a broken up compact bone layer on the condyle was interpreted as a post-mortem artefact. The results indicate adaptive response of the TMJs to the probably heavy masticatory function but do not support the suggested relationship between tooth wear and TMJ osteoarthrosis.

Dental conditions and temporomandibular joints in an early mesolithic bog man.

In 1994 parts of a human skeleton were found in the county of Västergötland, Sweden. The remains were probably from a man and estimated according to 14C dating to be about 9800 years old, i.e. from the Early Mesolithic Period. As such old finds are rare and the skull was well preserved a more detailed description is presented in this paper. The facial skeleton was robust and the face shape was rectangular. The remaining teeth, one maxillary and 10 mandibular teeth, exhibited no caries but extensive occlusal wear which in some teeth had exposed the pulp and led to periapical osteitis. Besides these teeth the 4 maxillary incisors and the two canines and one incisor in the mandible had been lost post-mortem, probably because of severe marginal bone loss. Both temporomandibular joints showed remodelling, one also osteoarthrotic changes. The observations are discussed with respect to masticatory function and some background factors.