8 research outputs found
The application of dental age estimation methods
Die Studie âThe chronology of third molar mineralization in the Austrian populationâa
contribution to forensic age estimationâ legt Referenzdaten zur Mineralisation des dritten
Molaren in der österreichischen Population vor. Im Rahmen dieser Querschnittsuntersuchung
wurden Panoramaröntgenaufnahmen von 610 ĂsterreicherInnen im Alter zwischen 12 und 24
Jahren gemÀà dem 8-gradigen Entwicklungsschema nach Demirjian et al. (1973) beurteilt.
Es wurde festgestellt, dass 78,2% der beurteilten Individuen beide mandibulÀren Molaren
besaĂen; bei 11,3% der Subjekte wurde ein unterer dritter Molar erfasst. Bisherige Erfahrungen
ĂŒber den zeitigeren Beginn der Weisheitszahnmineralisation bei Frauen wurden bestĂ€tigt. Ein
statistisch signifikanter Sexualdimorphismus wurde in den Stadien E (p<0,01) und F (p<0,05)
nach Demirjian beobachtet. Weiters wurde die Wahrscheinlichkeit eines österreichischen
Individuums ermittelt wenigstens 18 Jahre alt zu sein. Waren beide mandibulÀren Molaren
vorhanden, so betrug die Wahrscheinlichkeit wenigstens 18 Jahre alt zu sein 99,5 bzw. 99,3 % fĂŒr
MĂ€nner bzw. fĂŒr Frauen, jeweils im Falle der vollendeten Zahnmineralisation (Stage H nach
Demirjian). Dies legt nahe, dass Demirjians Stage H eine wertvolle Hilfe in der dentalen
AltersschĂ€tzung darstellt. Die gewonnenen Daten sind ausschlieĂlich fĂŒr österreichische
Individuen gĂŒltig und können nicht zur AltersschĂ€tzung in anderen Populationen herangezogen
werden. GemÀà den Empfehlungen der interdisziplinĂ€ren Arbeitsgemeinschaft fĂŒr Forensische
Altersdiagnostik inkludiert eine Altersbestimmung am Lebenden auĂerdem ein Handröntgen
sowie eine körperliche Untersuchung. Die Autorin befĂŒrwortet eine kombinierte Technik die
dazu beitrÀgt, inkorrekte AltersschÀtzungen aufgrund der biologischen Varianz eines einzelnen
Merkmals zu vermeiden. Trotzdem fehlt noch immer eine groĂe Studie, welche die Verwendung
der Methodenkombination validiert, obwohl sich selbige bereits in Verwendung befindet.
Die zweite Untersuchung âOn the applicability of secondary dentin formation to radiological age
estimation in young adultsâ untersuchte, ob bisher publizierte Regressionsgleichungen zur
dentalen AltersschÀtzung, basierend auf radiographischen, zweidimensionalen Messungen der
PulpagröĂe, zu reproduzierbaren und korrekten Ergebnissen fĂŒhren. Es wurden
Panoramaröntgenaufnahmen von 44 österreichischen Individuen, im Alter zwischen 13 und 24
Jahren, ausgesucht um die Messungen nach Kvaal et al. (1995) vorzunehmen. Die Verwendung
der Regressionsgleichung von Paewinsky et al. (2005) fĂŒhrte zu einer konsistenten
ĂberschĂ€tzung, die Gleichungen nach Kvaal et al. (1995) resultierten in einer konstanten
UnterschÀtzung des Alters. Aufgrund dieser Ergebnisse kann gefolgert werden, dass die Formeln
The Application of Dental Age Estimation Methods Zusammenfassung auf Deutsch
93
nach Kvaal et al. (1995) und Paewinsky et al. (2005) fĂŒr die dentale AltersschĂ€tzung junger
Erwachsener nicht geeignet sind. Es wird empfohlen SekundÀrdentinbildung anhand einer
groĂen Stichprobe der vorliegenden Altersgruppe zu evaluieren um verlĂ€ssliche Referenzdaten
hierzu erhalten. Weiters könnte es hilfreich sein, die Verminderung der PulpagröĂe anhand
zusÀtzlicher Parameter, wie von Cameriere et al. (2007b) vorgeschlagen zu ermitteln, oder aber
mittels Computertomographie (Yang et al. 2006).
Die dritte Studie âComparison of the validity of three dental methods for the estimation of age
at deathâ konzentrierte sich auf den Vergleich der Genauigkeit, des Bias sowie der PraktikabilitĂ€t
zweier makroskopischer und einer histologischen dentalen Methode zur SchÀtzung des
Sterbealters. Die Stichprobe bestand aus 67 ZĂ€hnen von 37 Individuen im Alter zwischen 20
und 91 Jahren. Die SchÀtzung des chronologischen Alters erfolgte gemÀà den Methoden nach
Lamendin et al. (1992) (LAM), Bang and Ramm (1970) (BR), sowie der Quantifizierung von
Zahnzementannulationen (TCA). Die höchste Genauigkeit des SchÀtzergebnisses zeigte die
TCA- Methode bei ZĂ€hnen der jungen, mittleren und alten Altersgruppe. LAM zeigte die
höchste PrÀzision in der jungen und alten Altersgruppe, wohingegen sich in der mittleren
Altersgruppe TCA als prÀziser erwies. TCA war die prÀziseste Methode, sofern die
Altersgruppen nicht getrennt analysiert wurden. BezĂŒglich des Bias hatten alle Methoden die
Tendenz das Alter in jungen Proben zu ĂŒberschĂ€tzen, sowie in alten Proben zu unterschĂ€tzen.
Die Ausnahme war hier TCA, die junge Erwachsene ohne Bias schÀtzte. Aufgrund der höheren
Genauigkeit und PrÀzision wird es empfohlen die TCA-Methode LAM und BR vorzuziehen,
sofern entsprechendes Wissen und Ausstattung vorhanden sind. Weitere Studien in Bezug auf
den genauen Mechanismus und die Chronologie der Zahnzementannulationen, der
SekundĂ€rdentinapposition, sowie der Dentintransparenz wĂŒrden die Genauigkeit von
AltersschÀtzungen verbessern. Weiters wÀre eine allgemein anerkannte Prozedur zur PrÀparation
und Evaluation von Zahnzementannulationen wĂŒnschenswert um einen gemeinsamen Standard
zu etablieren.The study âThe chronology of third molar mineralization in the Austrian populationâa
contribution to forensic age estimationâ provides reference data on third molar mineralization in
the Austrian population. Within the present cross-sectional evaluation panoramic radiographs of
610 Austrians between 12 and 24 years of age were assessed using the 8 developmental stages of
Demirjian et al. (1973).
It was found that 78.2% of the analyzed individuals possessed both mandibular third
molars; 11.3% of the subjects were recorded to have one lower third molar. Previous records
about an earlier occuring third molar mineralization in females were confirmed. A statistically
significant sexual dimorphism was noted in Demirjianâs stages E (p<0.01) and F (p<0.05). A
comparison with previous study data suggests ethnic differences in the timing of third molar
mineralization. Moreover, the probability of whether an Austrian individual is at least 18 years
old was determined. In the case where two mandibular third molars were present, the probability
for an Austrian individual to be at least 18 years is 99.5% and 99.3% for males and females,
respectively in the case were tooth mineralization is completed (Demirjianâs stage H). This
indicates that Demirjianâs stage H constitutes a reliable aid in dental age estimation. The obtained
data is exclusively valid in Austrian individuals and cannot be used for dental age estimation in
other populations. According to the recommendations of the interdisciplinary Study Group on
Forensic Age Diagnostics, an age analysis of living persons also includes an X-ray of the hand
and a physical examination. The author supports a combined technique that helps to avoid
incorrect age estimates due to the biological variance of a single trait. Nonetheless, a large study
that validates the use of the combination of methods is still lacking although this procedure is
already in use.
The second investigation âOn the applicability of secondary dentin formation to
radiological age estimation in young adultsâ aimed to explore whether previously published
regression formulae for dental age estimation based on radiographic two-dimensional
measurements of the pulp size lead to reproducible and statistically sound results. Panoramic
radiographs of 44 Austrian individuals, aged between 13 and 24 years, were selected to carry out
the measurements proposed by Kvaal et al. (1995). The use of the regression formulae reported
by Paewinsky et al. (2005) led to a consistent overestimation, the equations of Kvaal et al. (1995)
resulted in a constant underestimation of age. From these results it can be concluded that the
formulae of Kvaal et al. (1995) and Paewinsky et al. (2005) are not suitable for dental age
The Application of Dental Age Estimation Methods Summary of the Results and Outlook
91
estimation in young adults. It is suggested to evaluate secondary dentin formation with a large
sample size in the present age group to obtain reliable reference data. Furthermore, it could be
helpful to assess the decrease of the pulp size also by additional parameters as proposed by
Cameriere et al. (2007b) or via computerized tomography (Yang et al. 2006).
The third study âComparison of the validity of three dental methods for the estimation
of age at deathâ focused on the comparison of accuracy, bias, and practicability of two
macroscopic and one histological dental age at death estimation methods. The study sample
comprised of 67 teeth, obtained from 37 individuals aged 20 to 91 years. Chronological age was
estimated by means of the methods proposed by Lamendin et al. (1992) (LAM), Bang and
Ramm (1970) (BR), and the quantification of tooth cementum annulations (TCA). TCA was
found to be the most accurate age at death estimation method in young, middle, and old age
group teeth. LAM displayed the highest precision in the young, and the old age group whereas
TCA was more precise in the middle age group. TCA showed to be the most precise method
when the precision was calculated for all ages. Considering the bias, all methods displayed a
tendency to overestimate age in young and to underestimate it in old specimens. The exception
to this rule was TCA, which provided unbiased estimates for young adults. The higher accuracy
and precision recommends favouring TCA over LAM and BR, provided that the required knowhow
and equipment are available. Further studies in order to assess the exact mechanism and
timing of tooth cementum layering, secondary dentin apposition, and dentin sclerosis would be
helpful to improve the accuracy of age estimates. Moreover, a generally accepted procedure for
the preparation and evaluation of root cementum annulations would be desirable to establish
common standards
Silk fibroin microparticles as carriers for delivery of human recombinant bone morphogenetic protein-2 : in vitro and in vivo bioactivity
The in vitro and in vivo efficiency of fibroin microparticles as a delivery carrier for bone morphogenetic protein-2 (BMP-2) was evaluated. BMP-2 was encapsulated in silk fibroin particles that were produced by a simple and very mild processing method. The dose-response of BMP-2-loaded fibroin particles was examined in C2C12 cells, after 5 days of culture. The BMP-2 retained most of its activity as observed by the increase in alkaline phosphatase activity, which was much higher when BMP-2 was encapsulated into the particles rather than just surface-adsorbed. After 2 weeks of culture, increased mineralization was observed with BMP-2-loaded particles in comparison to soluble added growth factor. No significant cytotoxicity was detected. When implanted in a rat ectopic model, bone formation was observed by in vivo micro-computed tomography after 2 and 4 weeks postimplantation, with particles loaded with 5 or 12.5âmicrog BMP-2. An increase in bone density was observed over time. Histology revealed further evidence of ectopic bone formation, observed by strong alizarin red staining and osteocalcin immunostaining. Our findings show that fibroin microparticles may present an interesting option for future clinical applications in the bone tissue engineering field, and therefore, further studies have been planned.The authors acknowledge Anna Hofmann and Anna Khadem for additional help with some experiments, and Karin Brenner for animal maintenance. This work was supported by Fundacao para a Ciencia e Tecnologia (Ph.D. grant SFRH/BD/17049/2004), project ElastM (POCI/CTM/57177/2004 funded by FEDER and the Fundacao para a Ciencia e Tecnologia), Marie Curie Alea Jacta EST short-term grant (MEST-CT-2004-8104), and European STREP Project HIP-POCRATES (NMP3-CT-2003-505758). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
Non-invasive in vivo tracking of fibrin degradation by fluorescence imaging
Fibrin-based sealants consist of natural coagulation factors involved in the final phase of blood coagulation, during which fibrinogen is enzymatically converted by thrombin to form a solid-phase fibrin clot. For applications in tissue regeneration, a controlled process of matrix degradation within a certain period of time is essential for optimal wound healing. Hence, it is desirable to follow the kinetics of fibrinolysis at the application site. Non-invasive molecular imaging systems enable real-time tracking of processes in the living animal. In this study, a non-invasive fluorescence based imaging system was applied to follow and quantify site-specific degradation of fibrin sealant. To enable non-invasive tracking of fibrin in vivo, fibrin-matrix was labelled by incorporation of a fluorophore-conjugated fibrinogen component. Protein degradation and release of fluorescence were, in a first step, correlated in vitro. In vivo, fluorophore-labelled fibrin was subcutaneously implanted in mice and followed throughout the experiment using a multispectral imaging system. For the fluorescent fibrin, degradation correlated with the release of fluorescence from the clots in vitro. In vivo it was possible to follow and quantify implanted fibrin clots throughout the experiment, demonstrating degradation kinetics of approximately 16âdays in the subcutaneous compartment, which was further confirmed by histological evaluation of the application site
Gelatin embedding for the preparation of thermoreversible or delicate scaffolds for histological analysis
Thermoreversible hydrogels for tissue engineering (TE) purposes have gained increased attention in recent years as they can be combined with cells and drugs and directly injected into the body. Following the fate of transplanted cells in situ is essential in characterizing their distribution and survival, as well as the expression of specific markers or cell-matrix interactions. Existing histological embedding methods, such as paraffin wax embedding, can mechanically damage some biomaterials during processing. In this study, we describe a broadly applicable preparation protocol that allows the handling of delicate, thermoreversible scaffolds for histological sectioning. The gelatin solution permits the embedding of samples at 37 °C, which suits the solid phase of most TE scaffolds. A thermoreversible scaffold of polycaprolactone microparticles, combined with poly(polyethylene glycol methacrylate ethyl ether) and containing human adipose-derived stem cells, was prepared for histology by an initial gelatin embedding step in addition to the standard cryosectioning and paraffin processing protocols. Sections were evaluated by hematoxylin eosin staining and immunostaining for human vimentin. The gelatin embedding retained the scaffold particles and permitted the complete transfer of the construct. After rapid cooling, the solid gelatin blocks could be cryosectioned and paraffin infiltrated. In contrast to direct cryosectioning or paraffin infiltration, the extended protocol preserved the scaffold structure as well as the relevant cell epitopes, which subsequently allowed for immunostaining of human cells within the material. The gelatin embedding method proposed is a generalizable alternative to standard preparations for histological examination of a variety of delicate samples
Sunlight exposure exerts immunomodulatory effects to reduce multiple sclerosis severity
Multiple sclerosis (MS) disease risk is associated with reduced sunexposure. This study assessed the relationship between measures of sun exposure (vitamin D [vitD], latitude) and MS severity in the setting of two multicenter cohort studies (n(NationMS) = 946, n(BIONAT) = 990). Additionally, effect-modification by medication and photosensitivity-associated MC1R variants was assessed. High serum vitD was associated with a reduced MS severity score (MSSS), reduced risk for relapses, and lower disability accumulation over time. Low latitude was associated with higher vitD, lower MSSS, fewer gadolinium-enhancing lesions, and lower disability accumulation. The association of latitude with disability was lacking in IFN-beta-treated patients. In carriers of MC1R:rs1805008(T), who reported increased sensitivity toward sunlight, lower latitude was associated with higher MRI activity, whereas for noncarriers there was less MRI activity at lower latitudes. In a further exploratory approach, the effect of ultraviolet (UV)-phototherapy on the transcriptome of immune cells of MS patients was assessed using samples from an earlier study. Phototherapy induced a vitD and type I IFN signature that was most apparent in monocytes but that could also be detected in B and T cells. In summary, our study suggests benefidal effects of sun exposure on established MS, as demonstrated by a correlative network between the three factors: Latitude, vitD, and disease severity. However, sun exposure might be detrimental for photosensitive patients. Furthermore, a direct induction of type I IFNs through sun exposure could be another mechanism of UV-mediated immune-modulation in MS