Background:To evaluate morphologic,radiographic,and stereomicroscopic changes of teeth when subjected to specific high temperatures in both direct heat and gradual heat and to compare the changes among two heat groups...Background:To evaluate morphologic,radiographic,and stereomicroscopic changes of teeth when subjected to specific high temperatures in both direct heat and gradual heat and to compare the changes among two heat groups and also among different types of teeth.Materials and Methods:An in vitro study was conducted on 90 healthy extracted human teeth,in which the teeth were divided into two groups.Group 1(45)was subjected to direct heat and Group 2(45)was subjected to gradual heat.Group 1 and Group 2 were further subdivided into three subgroups(A)anteriors,(B)premolars,and(C)molars each consisting of 15 teeth.Teeth were subjected to temperatures of 200°C,400°C,600°C,800°C,and 1000°C in a muffle electric furnace.The color changes were noted using the Revised Munsell soil color chart and the radiographic and stereomicroscopic changes were evaluated.The results obtained were subjected to statistical analysis.Results:Teeth in direct heat showed more destructive changes at lower temperatures,i.e.,400°C and 600°C when compared to gradual heat where changes are observed at 600°C and 800°C.Among different types of teeth,anteriors and premolars showed more changes when compared to molars.Interpretation and Conclusion:It can be concluded that dental evidence may provide clues to solve the mystery in fire investigations as dental structures are the last to be destroyed under extreme conditions,whether temperature,acid,or putrefaction.展开更多
Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depe...Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depends on the relationship between the generation time of the document?s content and its stamping.Usually,a formal(legal)document would become effective once a seal is affixed,and normally,the content of the document is generated first and then subsequently stamped after being approved by the relevant personnel.Therefore,correctly identifying the sequence used to produce a document is necessary to detennine whether it is authentic or whether it may have been forged.However,because of the interference of many factors,the identification of such kind of forged documents has long been considered one of the most difficult technical issues in the field of questioned document identification.In this work,four nondestructive approaches to determine the order of photocopying and stamping were investigated:The stereomicroscope method,fluorescence microscopy,the three-dimensional pseudo-color method,and the contour ring method.Each method is associated with its own advantages and disadvantages,but all have been shown to produce some useful results relevant for determining the sequence of photocopying and stamping.展开更多
文摘Background:To evaluate morphologic,radiographic,and stereomicroscopic changes of teeth when subjected to specific high temperatures in both direct heat and gradual heat and to compare the changes among two heat groups and also among different types of teeth.Materials and Methods:An in vitro study was conducted on 90 healthy extracted human teeth,in which the teeth were divided into two groups.Group 1(45)was subjected to direct heat and Group 2(45)was subjected to gradual heat.Group 1 and Group 2 were further subdivided into three subgroups(A)anteriors,(B)premolars,and(C)molars each consisting of 15 teeth.Teeth were subjected to temperatures of 200°C,400°C,600°C,800°C,and 1000°C in a muffle electric furnace.The color changes were noted using the Revised Munsell soil color chart and the radiographic and stereomicroscopic changes were evaluated.The results obtained were subjected to statistical analysis.Results:Teeth in direct heat showed more destructive changes at lower temperatures,i.e.,400°C and 600°C when compared to gradual heat where changes are observed at 600°C and 800°C.Among different types of teeth,anteriors and premolars showed more changes when compared to molars.Interpretation and Conclusion:It can be concluded that dental evidence may provide clues to solve the mystery in fire investigations as dental structures are the last to be destroyed under extreme conditions,whether temperature,acid,or putrefaction.
文摘Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depends on the relationship between the generation time of the document?s content and its stamping.Usually,a formal(legal)document would become effective once a seal is affixed,and normally,the content of the document is generated first and then subsequently stamped after being approved by the relevant personnel.Therefore,correctly identifying the sequence used to produce a document is necessary to detennine whether it is authentic or whether it may have been forged.However,because of the interference of many factors,the identification of such kind of forged documents has long been considered one of the most difficult technical issues in the field of questioned document identification.In this work,four nondestructive approaches to determine the order of photocopying and stamping were investigated:The stereomicroscope method,fluorescence microscopy,the three-dimensional pseudo-color method,and the contour ring method.Each method is associated with its own advantages and disadvantages,but all have been shown to produce some useful results relevant for determining the sequence of photocopying and stamping.
