No description available.

Various traumatic events such as automobile accidents, structure fires, or terrorist attacks result in traumatic and thermal injury. Fire is a destructive force that can alter or destroy evidence, and thermal alterations have negative effects on forensic and anthropological recovery and analysis. Blunt force trauma is particularly difficult to analyze because of the multiple ways in which this trauma appears on a body and the variety of objects that can impact and fracture a bone or the variety of ways a body can impact a blunt surface. As fire is a common way to cover up a crime and blunt force trauma is used as a means to kill or injure an individual, it is necessary to understand the differences between these two types of fractures that can present together on bone. The present study was performed to determine the amount of survivability of traumatic fracture patterns in remains that have been exposed to a burning event. The sample used for this investigation was composed of twenty limbs (forty long bones) from five full-grown, domestic, female sheep (Ovis aries) obtained from a farm in Connecticut. Thirty specimens were traumatized with the head of an Estwing ball peen hammer and ten were left as controls. After specimens were subjected to blunt force trauma, each was radiographed using Computed Tomography. They were then placed in a small structure, 8' x 8', that was constructed to simulate the conditions of a house fire. Each post-burn bone was analyzed based on a number of characteristics. A trauma score of "1" no trauma, "2" ambiguous, and "3" traumatic fractures were given based on these observations. CT scans were examined after bone samples had been analyzed. Again, each specimen's CT scan was given a trauma score ("1" no trauma, "2" ambiguous, and "3" traumatic fractures). Results from the bone analysis on the 30 traumatized and burned specimens revealed that 15 did not have trauma, 2 were ambiguous (i.e., they may have trauma but traumatic characteristics were not distinct), and 13 presented with distinguishable traumatic injury. Comminuted was the most prominent type of fracture, and the next most common fracture was oblique. The majority of traumatic injury was found on the middle portion of the bone. CT examination showed that 12 specimens had suffered traumatic injury. The two analyses were compared and showed an agreement of 83.3% between the trauma scores. Results show that differentiation of traumatic and thermally induced fractures is possible using various fracture characteristics as well as taphonomic indicators to determine the sequence of events.

This project examined the effects of burning on saw mark characteristics of isolated semi-fleshed white-tailed deer (Odocoileus virginianus) long bones as a substitute for human remains. Different classes of saws were examined to determine which type of saw mark characteristics are obliterated when burned and which are not. The saw mark characteristics that were examined are superficial false start scratches, false start kerfs, and completely sectioned cuts with breakaway spurs/notches. The long bones were burned at the Boston University School of Medicine using a muffle furnace, at differing temperatures and at differing time increments. The author hypothesized that the higher the temperature and the longer the duration of bone burning, the greater will be the obliterative effect on saw mark characteristics. All samples were examined using a Motic® Digital Light Microscope 12 VDC with a Nikon® MKII Fiber Optic Light attached with accompanying Motic® imaging and measuring software. Distances were measured between striations on complete cuts, false start kerf widths, and false start scratch widths using the Motic® imaging and measuring software. Images were also taken of the cross sections of the kerf floors. The striations on the kerf walls, false start kerf widths, and false start scratch widths were compared to the control samples. Measurements taken from false start scratches, false start kerfs, and complete cuts were averaged and compared to the averages from each temperature and the control samples, to assess the degree of shrinkage from thermal alteration. The false start kerf profile shapes were blindly examined and classified into Class A, B, C, or D(following the system of Symes 1992) and compared to the control samples. Kerf flare and blade drift were examined to determine if thermal alteration obliterated those saw mark characteristics. The chainsaw false start kerfs and complete cuts were examined macroscopically to determine what effects thermal alteration had on those types of marks. All thermally altered samples were assessed for color change, heat-related fracturing, and whether or not the saw marks were still visible. The author found that all saw marks made with the mitre saw, crosscut saw, and bow saw were still visible and identifiable, even in a fractured state and, when burned up to 700°C for one hour. Most of the false start kerf samples were classified into the correct kerf profile shape as outlines in Symes (1992). False start kerfs and complete cuts made with the chainsaw were blindly examined and showed that these marks are distinct and easily identifiable when the bone is completely intact or has very minimal fracturing. The crosscut saw false start scratch and crosscut saw complete cut samples showed signs of shrinkage. The average width of the false start scratch samples burned at 700°C for one hour was about 50% smaller than the control sample's average width. The same was true for the complete cut striation widths. Shrinkage did not appear to alter the crosscut saw false start kerf widths or the bow saw false start scratch widths. For all cuts made with the mitre saw shrinkage did appear to alter the samples. Warping did occur where some of the burned averages were larger than the control sample averages. This suggests that some warping did take place by widening the kerf, thus changing the analysis of the saw mark characteristics. Blade drift and kerf flare were seen in the samples and thus were not affected by thermal alteration. The author's hypothesis was not rejected, because in some cases thermal alteration did modify the saw mark characteristic measurements and in some cases thermal alteration did not alter the measurements. Some of the saw marks were affected by shrinkage, while others were not. False start kerf profile shape classification was not affected by thermal alteration. The chainsaw samples were affected most by the thermal alteration, because of the obliterative effects of heat-related fracturing which progressed generally with the greater temperature.

No description available.

O objetivo deste estudo foi avaliar a alteração de temperatura durante preparo cavitário em dentina cariada e hígida e a eficiência na remoção de tecido cariado com Er:YAG. Foram utilizados 30 terceiros molares humanos hígidos, doados pelo Banco de Dentes da FORP-USP, os quais tiveram suas raízes removidas e as coroas seccionadas, obtendo-se 60 fragmentos de 2,5mm de espessura. Os espécimes foram divididos em 2 grupos (n=30): dentina cariada e dentina hígida (controle) e em 3 subgrupos (n=10), de acordo com as freqüências de laser aplicadas (4, 6 e 10Hz). Foi empregada energia constante de 200mJ no modo não-contato, focado e sob refrigeração. A indução das lesões artificiais de cárie foi realizada pelo modelo bacteriano, no qual foram utilizadas cepas de Streptococcus mutans. O registro da temperatura foi realizado antes do inicio da irradiação, após 10 segundos e ao final do preparo. Após este procedimento, os fragmentos foram analisados por DIAGNOdent® e microscopia óptica de luz, utilizando-se o software Axio Vision 4.3 LE, para quantificar a remoção de dentina cariada. Para a análise morfológica, 5 espécimes de cada grupo foram aleatoriamente selecionados e preparados para microscopia eletrônica de varredura. Os dados foram submetidos à Análise de Variância α=5% e, quando apropriado, ao teste de Fisher. Os resultados mostraram que todas as freqüências do laser Er:YAG promoveram aumento gradual e significante da temperatura durante o preparo cavitário, independente do substrato. Com relação às freqüências de laser empregadas, observou-se que apenas a de 10Hz promoveu aumento diferencial de temperatura, sendo observado neste subgrupo o maior acúmulo de calor, em ambos os substratos. A análise por Diagnodent® revelou que a remoção de tecido cariado foi semelhante entre os subgrupos de 4 e 6Hz, e maior no de 10Hz. Contudo, por microscopia óptica de luz, os subgrupos de 6 e 10Hz foram estatisticamente iguais e o de 4Hz apresentou os menores valores de remoção de tecido cariado. A avaliação morfológica da superfície e subsuperfície dos espécimes revelou a presença de tecido dentinário desmineralizado em todos os subgrupos estudados. Contudo, em preparos realizados com 4Hz, foi observado que a dentina cariada remanescente apresentava sua estrutura colágena desnaturada. Assim, conclui-se que o aumento da freqüência do laser Er:YAG promove aumento gradativo e significante da temperatura em função do tempo, independentemente do substrato, não atingindo níveis nocivos ao tecido pulpar e uma ablação mais eficiente do tecido dentinário cariado e que a irradiação do tecido dentinário cariado resulta em uma superfície mais uniforme em relação ao tecido dentinário hígido. / The aim of this study was to evaluate the thermal alterations during cavity preparation with sound and caries dentin and dentin caries removal efficiency using Er:YAG laser. Thirty humans molars, donated by FORP-USP Teeth Bank, had the root removed and the crown sectioned getting sixty fragments with 2.5-mm thick. The fragments were assigned into two groups (n=30): artificial dentin caries and sound dentin (control group) and 3 subgroups (n=10), according to the irradiation frequency used (4, 6, or 10Hz) at a constant energy level of 200mJ, focused-mode and under refrigeration. The artificial caries lesion was obtained by the bacterial model with was used Streptococcus mutans. Before irradiation, a thermocouple, adapted to the tooth fragment, recorded the initial temperature value (°C); then, the temperature was measured at every 10s during irradiation and after finishing irradiation. A caries detection system (DIAGNOdentTM) and a light microscopy software (Axion VisionTM) was employed to evaluate the demineralized dentin removal. The morphologic analyses used 5 fragments randomly selected from each group and processed for the accomplishment scanning electron microscope. Data were analyzed by ANOVA and Fishers tests (α=5%). The results revealed that the temperature increased gradually over time for all groups, independent the type of substrate. Concerning the frequencies it was observed that irradiation with 10Hz promoted the highest temperature values for both substrates and it was statistical different of remaining frequencies. The caries detection system revealed that the caries removal was similar with 4 and 6Hz, and was superior with 10Hz. However with the light microscopy software the frequency the caries removal was similar with 6 and 10Hz and the frequency of 4Hz presented the lowest caries removal values. The surface and subsurface morphologic analyses revealed the presence of demineralized dentin in all frequencies studied. However in the preparation carried through with 4Hz, the remaining dentine beyond demineralized, presented its collagen structure disorganized. It can be concluded by the present study that the Er:YAG laser frequency increase provides a higher temperature increase for sound and caries dentin, however without reaching harmful levels to the dental pulp, as well a greater caries dentin removal and the caries dentin irradiation provides a regular surface compared with sound dentin.

O objetivo deste estudo foi avaliar a alteração de temperatura durante preparo cavitário em dentina cariada e hígida e a eficiência na remoção de tecido cariado com Er:YAG. Foram utilizados 30 terceiros molares humanos hígidos, doados pelo Banco de Dentes da FORP-USP, os quais tiveram suas raízes removidas e as coroas seccionadas, obtendo-se 60 fragmentos de 2,5mm de espessura. Os espécimes foram divididos em 2 grupos (n=30): dentina cariada e dentina hígida (controle) e em 3 subgrupos (n=10), de acordo com as freqüências de laser aplicadas (4, 6 e 10Hz). Foi empregada energia constante de 200mJ no modo não-contato, focado e sob refrigeração. A indução das lesões artificiais de cárie foi realizada pelo modelo bacteriano, no qual foram utilizadas cepas de Streptococcus mutans. O registro da temperatura foi realizado antes do inicio da irradiação, após 10 segundos e ao final do preparo. Após este procedimento, os fragmentos foram analisados por DIAGNOdent® e microscopia óptica de luz, utilizando-se o software Axio Vision 4.3 LE, para quantificar a remoção de dentina cariada. Para a análise morfológica, 5 espécimes de cada grupo foram aleatoriamente selecionados e preparados para microscopia eletrônica de varredura. Os dados foram submetidos à Análise de Variância α=5% e, quando apropriado, ao teste de Fisher. Os resultados mostraram que todas as freqüências do laser Er:YAG promoveram aumento gradual e significante da temperatura durante o preparo cavitário, independente do substrato. Com relação às freqüências de laser empregadas, observou-se que apenas a de 10Hz promoveu aumento diferencial de temperatura, sendo observado neste subgrupo o maior acúmulo de calor, em ambos os substratos. A análise por Diagnodent® revelou que a remoção de tecido cariado foi semelhante entre os subgrupos de 4 e 6Hz, e maior no de 10Hz. Contudo, por microscopia óptica de luz, os subgrupos de 6 e 10Hz foram estatisticamente iguais e o de 4Hz apresentou os menores valores de remoção de tecido cariado. A avaliação morfológica da superfície e subsuperfície dos espécimes revelou a presença de tecido dentinário desmineralizado em todos os subgrupos estudados. Contudo, em preparos realizados com 4Hz, foi observado que a dentina cariada remanescente apresentava sua estrutura colágena desnaturada. Assim, conclui-se que o aumento da freqüência do laser Er:YAG promove aumento gradativo e significante da temperatura em função do tempo, independentemente do substrato, não atingindo níveis nocivos ao tecido pulpar e uma ablação mais eficiente do tecido dentinário cariado e que a irradiação do tecido dentinário cariado resulta em uma superfície mais uniforme em relação ao tecido dentinário hígido. / The aim of this study was to evaluate the thermal alterations during cavity preparation with sound and caries dentin and dentin caries removal efficiency using Er:YAG laser. Thirty humans molars, donated by FORP-USP Teeth Bank, had the root removed and the crown sectioned getting sixty fragments with 2.5-mm thick. The fragments were assigned into two groups (n=30): artificial dentin caries and sound dentin (control group) and 3 subgroups (n=10), according to the irradiation frequency used (4, 6, or 10Hz) at a constant energy level of 200mJ, focused-mode and under refrigeration. The artificial caries lesion was obtained by the bacterial model with was used Streptococcus mutans. Before irradiation, a thermocouple, adapted to the tooth fragment, recorded the initial temperature value (°C); then, the temperature was measured at every 10s during irradiation and after finishing irradiation. A caries detection system (DIAGNOdentTM) and a light microscopy software (Axion VisionTM) was employed to evaluate the demineralized dentin removal. The morphologic analyses used 5 fragments randomly selected from each group and processed for the accomplishment scanning electron microscope. Data were analyzed by ANOVA and Fishers tests (α=5%). The results revealed that the temperature increased gradually over time for all groups, independent the type of substrate. Concerning the frequencies it was observed that irradiation with 10Hz promoted the highest temperature values for both substrates and it was statistical different of remaining frequencies. The caries detection system revealed that the caries removal was similar with 4 and 6Hz, and was superior with 10Hz. However with the light microscopy software the frequency the caries removal was similar with 6 and 10Hz and the frequency of 4Hz presented the lowest caries removal values. The surface and subsurface morphologic analyses revealed the presence of demineralized dentin in all frequencies studied. However in the preparation carried through with 4Hz, the remaining dentine beyond demineralized, presented its collagen structure disorganized. It can be concluded by the present study that the Er:YAG laser frequency increase provides a higher temperature increase for sound and caries dentin, however without reaching harmful levels to the dental pulp, as well a greater caries dentin removal and the caries dentin irradiation provides a regular surface compared with sound dentin.