Timing of Demirjian's tooth formation stages.

BACKGROUND: Global differences in Demirjian et al.'s method of assessing dental maturity are thought to be due to population differences. AIM: The aim of this study was to investigate the timing of individual tooth formation stages in children from eight countries. RESEARCH DESIGN: This was a meta-analysis of previously published data from retrospective cross-sectional studies of dental maturity. METHOD: Data of mandibular permanent developing teeth from panoramic radiographs (Demirjian's stages) were combined from Australia, Belgium, Canada, England, Finland, France, South Korea and Sweden (n = 9002, ages 2-16.99 years). Age-of-attainment was calculated using logistic regression for each group by sex and meta-analysis of the total. Overlapping 95% confidence intervals of the means was interpreted as no significant difference. RESULTS: Mean ages for each group and total were significantly different in 65 out of 509 comparisons (p < 0.05). Some of these were of small sample size but there was no consistent pattern. Apex closure of the first molar was significantly later in children from Quebec and this might explain differences found in the dental maturity score. CONCLUSIONS: These results suggest no major differences in the timing of tooth formation stages between these children. This fails to explain previous findings of differences using Demirjian's dental maturity method.

A modification of the Demirjian method for age estimation in children.

The Demirjian method for age estimation in children by means of dental development is widely used and forms a basis on which a universal dental maturity score can be calculated. This score is then translated into a chronological age with aid of tables specific for each population. Such tables are, however, available for only a few populations and usually not where age estimations are needed. In several studies on age estimation in children it has been found that the original studies by Demirjian and co-workers do not give enough information to allow the construction of corresponding tables for other populations. The main reason for this is that the regression lines in the original graphs were obtained by manual smoothing to combine the individual plots and the tables were thereafter compiled from these graphs. In an attempt to avoid manual, and more or less subjective, construction of the regression line, an attempt was made to fit the plots into a regression line by a series of predefined functions. The aim was to find a model with the best possible explanation factor of the correlation between dental maturity score and chronological age. A cubic function was found to give a good fit to the plots with an R2 of about 0.95. This modification of the original Demirjian method for age estimation of children is therefore recommended for the construction of population-specific tables. The use of a mathematical function also makes it possible to calculate confidence intervals to be used to describe the accuracy of an individual estimation.

A comparison between dental maturity rate in the Swedish and Korean populations using a modified Demirjian method.

Several studies have examined variations in the rate of dental development in children from different populations using the Demirjian method for age estimation in children. Most of them have shown a more or less consistent difference between the French-Canadian population, used to construct the original method, and the population studied. In most instances the Canadian population was lagging behind in the dental development, varying from a few months up to about 1 year. In an earlier study we have showed that there may be problems with the Demirjian method and a modification using a cubic regression model was suggested instead of the manually fitted original model. With this new model the rate of dental development between the Swedish and Korean populations was compared. There were highly statistically significant differences for both boys and girls, demonstrating that Swedish boys are about 2 months, and girls about 6 months earlier in their dental development at certain ages when compared to Korean children.

Demonstration and semi-quantification of mtDNA from human dentine and its relation to age.

In order to study if mitochondrial DNA (mtDNA) could be retrieved from isolated human dentine, small pieces of dentine were cut out from the central part of the apical half of wisdom teeth from 21 individuals aged 15 to 85 years. The dental pulp was used as a control. After extraction, amplification and agarose gel electrophoresis the amount of mtDNA was semi-quantified from the intensity of the stained bands in the gel. Mitochondrial DNA was retrieved from all samples and the sequences were identical in pulp and dentine from each individual. There was a clear age-dependent decrease in the amount of amplified mtDNA. Since the odontoblastic processes in the apical dentine undergo degeneration with age and the dentinal tubules subsequently become occluded with calcium phosphate crystals, the conclusion was drawn that even after dissolution of the odontoblastic processes, at least remains of the mtDNA are trapped in the dentine. This well protected mtDNA could thus be regarded a good source of DNA in identification cases with severe degradation.

Gender determination by odontometrics in a Swedish population.

Gender determination of skeletal remains is fraught with uncertainty, especially in subadults. Many anatomical structures have been studied, but the teeth and their measurements seem to be the most reliable method in individuals whose secondary sexual characteristics have not yet developed. The purpose of this study was to investigate the accuracy with which gender can be differentiated by odontometric analyses in the Swedish population. The material consisted of 58 dental casts, 29 male and 29 female, ranging in age from 14 to 38 (mean 19) years. Measurements were made on the mesio-distal, bucco-lingual, mesiobuccal-distolingual and distobuccal-mesiolingual diameters. The mean diameters for males were larger than those for females in all variables and 27 out of the 56 differences were statistically significant (p < 0.05). The upper canine had significant mean differences in all measurements. Lower canines, second upper and lower premolars, upper second molars and the lower first molars all had significant mean values in three of four variables. These findings support the usefulness of especially the canines in gender determination by odontometric analyses. It also shows high significant dimorphic values for some of the other variables investigated.

Mitochondrial DNA extraction and typing from isolated dentin-experimental evaluation in a Korean population.

This study reports mtDNA polymorphisms in both hypervariable segments HV1 and HV2 of the non coding D-loop region from 60 unrelated Koreans. In contrast to two previous Korean data base studies, mtDNA was extracted separately from pulp tissue and root dentin of teeth obtained from dentists. Dentin turned out to be a reliable source of mitochondrial DNA. This can be of practical importance in forensic identification case work after a long post-mortem interval since pulp decomposes rapidly. The extraction method is explained in detail. The mtDNA polymorphisms obtained from 60 teeth of unrelated Koreans were compared with the already existing Korean data base.

Prevalence of perceived symptoms of dry mouth in an adult Swedish population--relation to age, sex and pharmacotherapy.

The aim of the study was to evaluate the prevalence of subjective perception of dry mouth in an adult population and to determine the prevalence of pharmacotherapy in this population. An additional aim was to assess a possible co-morbidity between symptoms of dry mouth and continuing pharmacotherapy. Four-thousand-two-hundred persons were selected at random from the national census register of the adult population of the southern part of the province of Halland, Sweden. The sample was stratified according to age and sex, and 300 men and an equal number of women aged 20, 30, 40, 50, 60, 70 and 80, were included. A newly developed questionnaire was mailed to each individual. In addition to questions about subjective perception of dry mouth, the subjects were asked to report on present diseases and continuing pharmacotherapy. Three-thousand-three-hundred and thirteen (80.5%) evaluable questionnaires were returned. The estimated prevalence of xerostomia in the population was 21.3% and 27.3% for men and women, respectively. This difference between the sexes was statistically significant. In non-medicated subjects, women tended to report a higher prevalence of xerostomia compared with men, 18.8% vs. 14.6%, and also among medicated subjects the estimated prevalence of dry mouth was higher for women than for men, 32.5% vs. 28.4%. There was a strong association between xerostomia and increasing age and also between xerostomia and continuing pharmacotherapy. The average prevalence of dry mouth among medicated and non-medicated subjects was 32.1% and 16.9%, respectively, the difference being statistically significant. There was also a strong association between xerostomia and the number of medications. In a logistic regression, the probability of reporting mouth dryness was significantly greater in older subjects and in women, and the probability increased with the number of medications taken. In conclusion, this epidemiological survey of an adult population has demonstrated that women, independent of age, do report a higher prevalence of xerostomia than men and that the symptom of dry mouth is strongly associated with age and pharmacotherapy. It is, however, not possible to discriminate between disease and pharmacotherapy as causal factors.

Enamel incremental lines as recorders for disease in infancy and their relation to the diagnosis of SIDS.

The sudden infant death syndrome (SIDS) is a major diagnosis of post-neonatal mortality in the industrialised countries. The cause of death is, however, still elusive. The development of complementary diagnostic methods widening the possibility to analyse the postmortem findings is therefore important. The aim of this study was to histologically examine the enamel of teeth from children dying suddenly and unexpectedly in order to disclose if the presence of enamel disturbances corresponded to neo- or postnatal disorders. During enamel formation ameloblasts are susceptible to local and systemic disturbances which may be reflected in the fully formed enamel as hypoplasia, hypocalcification or accentuated incremental lines. Nineteen consecutive cases of deaths in infants between 1-19 months of age were investigated at the Department of Forensic Pathology, Stockholm, Sweden. The analyses of anamnestic and postmortem data and the analyses of incremental lines were done independently without knowledge of the conclusion of the other part. The results show a good agreement between enamel changes on one hand and the antemortem history and the autopsy findings on the other. This type of investigation may be a valuable complement to the ordinary postmortem investigations of a child who has suddenly and unexpectedly died.

Individual variation of tooth development in Swedish children.

The distributions of the developmental stages of the mandibular teeth have been studied according to the method by Demirjian et al (1973), in Swedish children. 197 panoramic radiographs of children aged 5, 6, 9 and 12 years were collected and examined by each of 13 independent pedodontists, radiologists and forensic odontologists. The results showed that the individual variation of tooth development was large, and that children of the same age generally showed a dispersion over four stages, and that, in extreme cases, children of 5 and 12 years of age could show the same developmental stages. Generally girls were ahead of the boys in development at all ages. It thus appears as if any method for age determination of children with aid of tooth development will be suffering from a rather wide range of uncertainty owing to the individual variation.

Intra- and inter-examiner variations in four dental methods for age estimation of children.

The intra- and inter-examiner variations of the estimated chronological ages of children were studied with the methods described by Gustafson & Koch (1974), Liliequist & Lundberg (1971), Demirjian et al. (1973) and Haavikko (1974). Orthopantomographs of 197 children aged 5, 6, 9, and 12 years were evaluated by 13 independent examiners to study the inter-examiner variations, and 28 orthopantomographs were examined twice by 12 examiners to evaluate the intra-examiner variation. The result showed an overall good agreement between the first and second rating, even if there were some non-systematic differences between the two ratings with some methods at some ages. However, different examiners could differ considerably from each other when rating the same radiograph, and consequently a wide range of estimated ages was obtained. There was no single outlier examiner who systematically differed from the others, but the extremes varied from examiner to examiner for the different children.

Estimation of chronologic age using the aspartic acid racemization method. I. On human rib cartilage.

Determinations of chronologic age are of great importance in forensic science. At present the aspartic acid racemization method on teeth provides one of the best means in adult individuals. However, if teeth are not available, some other stable tissue has to be used. In this study, the applicability of cartilage from the ribs has been tested. Specimens of rib cartilage were obtained at autopsy from 24 individuals aged 0.2-96 years. An acid-soluble peptide (SP) fraction and an insoluble collagen-rich (IC) fraction were prepared, and the ratio of D/L aspartic acid was determined using the HPLC technique. The correlation coefficient between the D/L ratio and age was r = 0.91 in SP and r = 0.97 in IC. It thus seems as if cartilage from non-weight-bearing areas may be a useful source of tissue for the estimation of chronologic age with the aspartic acid racemization method when teeth are not available.

Estimation of chronologic age using the aspartic acid racemization method. II. On human cortical bone.

Over the last 20 years a new chemical method, base on the racemization of aspartic acid, has been developed to be used for the estimation of chronologic age in adult individuals. The method has a good accuracy when used on dental enamel, dentine and cartilage. However, in forensic and archeological cases teeth and cartilage are not always available. Since preliminary studies have shown that there are some age-related changes of the D/L aspartic acid ratio also in bone, this study was carried out to further explore if the method could be used for age estimations of bone. Bone samples from 24 individuals, aged 0.2 to 95.6 years were analysed for the D/L ratios with HPLC-technique. Two different fractions of the bone were examined, an acid-soluble peptide fraction and an acid-insoluble collagen-rich fraction. The analyses showed age-related racemizations in both fractions, although of different rates. The correlation coefficients with age were 0.72 in the peptide fraction, and 0.84 in the collagen-rich fraction. It thus seems as if bone may be used for age estimations when more stable tissues like dentine and cartilage are not available.

The validity of four methods for age determination by teeth in Swedish children: a multicentre study.

Four principally different methods for age determination of children by means of teeth have been tested on a Swedish population. 197 panoramic radiographs of children aged 5, 6, 9 and 12 years were collected and examined by 13 independent pedodontists, radiologists and forensic odontologists. The results showed a satisfactory precision for those methods which have been developed on a Scandinavian population, but a method from a French-Canadian population showed a consistent over-estimation when used on the Swedish children.

Estimation of dental age using HPLC-technique to determine the degree of aspartic acid racemization.

Age determinations of adult individuals are of great importance within the forensic sciences. Presently, age changes in the teeth provide good means for this. The best method up to now has been "Gustafson's method" with modifications. Over the last 10 years a new chemical method, based on the racemization of aspartic acid in enamel and dentine, has been developed. Enamel and dentine belong to the very few tissues that do not have metabolic turn-over after formation. Both reliability and validity have been shown to be high, and this method therefore seems to be the best choice for the future. However, most studies to date have been using expensive and special instruments (gas chromatographs or amino acid analyzers) for these determinations. This study was performed to explore if the same determinations can be carried out with ordinary HPLC technique. It was shown that there is a good correlation between the ratio of D- and L-forms of the aspartic acid and age of the tooth. The correlation coefficient was 0.97, which is close to those presented with the other techniques, where r has been 0.95 - 0.99. The prediction of an individual age can be made with a 95% confidence interval of about +/- 12 years.

Age estimation with the aid of tooth development: a new method based on objective measurements.

The common methods of age determination with the aid of teeth have been criticized because they rely on subjective estimations of tooth development, as seen in radiographs, and subsequent comparisons with pictures and descriptions in compiled dental charts. The distribution around an estimated age with these methods is usually more than +/- 2 yr between the 10th and 90th percentiles. In an attempt to avoid subjective estimations, objective measurements of developing teeth were correlated with subjects' chronologic ages. The structures measured were crown height, apex width, and root length. With the aid of a multiple regression model, a linear relationship between some of these distances and age was shown. The distances which were best correlated with age differed according to sex and age. This method has a 95% C.I. of about +/- 2 yr around an estimated age. It therefore seems to be more accurate than the earlier methods. Thus, the individual variation in tooth development is of the same order of magnitude, and a better estimation can therefore not be done in children 6-14 yr of age.

Ten years of forensic odontology: a report from the Department of Forensic Odontology, Stockholm, Sweden.

The practical activities of the Department of Forensic Odontology at the National Board for Forensic Medicine in Stockholm, Sweden, have been reviewed over a ten year period (1980-1989). The number of cases has increased from 72 in 1980 to 278 in 1989, and a total of 1402 tasks have been carried out. Seventy-five per cent of the cases have concerned identification of single individuals, 14% have involved the National Register of Missing Persons with the remaining cases being age determination (34), bite marks (27), oral examination after criminal assault (69), examination of skeletal remains, dentures, restorative materials (33) and written reports to be presented at court (159).

Comprehensive medical examination of a group of patients with alleged adverse effects from dental amalgams.

Mercury from dental amalgams does not seem to cause dose-related intoxications. However, animal studies have shown that high-dose exposure to mercury may support various types of immunologic reactions. Ten patients claiming that their symptoms were caused and aggravated by amalgam therapy were selected for a study of the effects of removal of one amalgam restoration followed by placing of a composite filling. Clinical symptoms and the result of laboratory tests were recorded. Six patients had contact allergies to metals, three of them to mercury ammonium chloride. The comparison of pre- and post-experimental test results showed significant reductions in p-IgE and dU-albumin and significant increases in p-C3d and dU-beta 2-microglobulin. There was no laboratory evidence of a direct toxic effect by mercury on the patients. The observed response by some of the studied factors to the low acute exposure to amalgam may imply that an activation of the immune system occurred.

Age estimation based on tooth development: a test of reliability and validity.

The precision and accuracy of three commonly used methods for age determination by teeth were studied in 541 children aged 5.5-14.5 yr. These methods rely on estimation of tooth development as seen in radiographs compared with compiled dental charts. It was found that charts made from Scandinavian populations gave a rather good precision, while one from a Canadian population gave a consistent overestimate. Dependent on the method used, sex, and age, the 95% confidence interval for an individual prediction could be more than +/- 2 yr.

Effects of chronic stimulation of salivary gland beta-adrenoceptors on saliva composition and caries development in the rat.

The effects of long-term beta-adrenoceptor stimulation or inhibition on parotid and submandibular glands, saliva secretion, and caries development were studied. Groups of rats were treated daily with: 0.5 or 5 mg/kg body weight of isoproterenol (IPR), 0.5 or 5 mg/kg bw propranolol (PRO), or saline. After 42 days, saliva was collected and analyzed for secretion rate, total protein, amylase, sialic acid and electrolytes. Total protein and amylase in saliva decreased and potassium increased in the high IPR group. Phosphate increased in both IPR groups and decreased in the high PRO group. The average weight of parotid glands increased 3.7 times in the high IPR group and 1.8 times in the low IPR group. Amylase and total protein in parotid gland extracts decreased in both IPR groups. The submandibular gland weight increased 1.5 times in the high IPR group. Total protein decreased in the high IPR group. There was no difference in caries development.