Biomedical subjects
Helena Ranta
Publications and source records attributed to Helena Ranta.
Reliability and validity of eight dental age estimation methods for adults.
This paper evaluates the reliability and validity of eight published dental age estimation methods for adults that may aid in victim identification. Age was calculated on 20 Caucasian teeth of known age according to the methods of Kvaal (for in situ and extracted teeth), Solheim (for in situ and sectioned teeth), Lamendin (for extracted teeth), Johanson (for sectioned teeth) and Bang (for extracted and sectioned teeth) by one independent observer. For each method, mean age error and standard error were assessed as the measures of accuracy and precision. In addition, method simplicity, requirements for tooth preparation and the equipment necessary were assessed and recommendations given for forensic use in various situations. Methods for sectioned teeth gave more reliable results when compared to methods for intact teeth.
Tooth formation and the mandibular symphysis during the first five postnatal months.
Schedules based on tooth development are useful in age assessments of children, but in early infancy they are based on only a few studies. The radiographic appearance of the mandibular symphysis during the first postnatal months has not gained attention. The present study describes the formation of teeth and the development of fusion between the mandibular halves during the first five postnatal months, as seen in panoramic tomograms taken in medicolegal autopsies of 29 ethnic Finns, 19 boys and 10 girls, at the Department of Forensic Medicine, University of Helsinki. In the majority of the infants, the criteria of sudden infant death (SID) were fulfilled. The stages of tooth formation used were those applied by Moorrees et al. with one modification (Nyström et al.). Mineralization of all primary teeth proceeded rapidly during the first postnatal months, the change being on average two developmental stages in four months. Considerable variation in tooth development existed in infancy. The mandibular halves were separated at birth. Complete fusion had occurred in the majority of infants aged four months, and the tomograms of the remaining infants showed a thin vertical line in a part of the symphysis. The marked changes, which during the first postnatal months occur in the radiographical appearance of the mandibular symphysis, and in the formation of primary teeth, provide valuable information for age assessments of infants.
Dentists' qualifications affect the accuracy of radiographic identification.
This study assessed the effects of forensic odontologists' training and experience upon the accuracy of their dental radiographic identifications. Forty participating odontologists with various levels of training and experience completed a Web-based survey of their qualifications and then completed nine Web-based radiographic identification cases. They made their identifications using the American Board of Forensic Odontology Categories and Terminology for Body Identification. The results indicate that odontologists with high levels of training and experience performed significantly more accurately than those with lower levels. We conclude that high levels of training and experience in forensic odontology should be developed, maintained, and required of dentists who participate in a forensic team dealing with challenging identification cases.
Morphology of experimental assault rifle skin wounds.
Finnish forensic experts who had performed investigations of victims of alleged political violence in Kosovo, in the Federal Republic of Yugoslavia, under the mandate of the European Union, carried out experimental shooting in Finland to confirm observations made during the earlier forensic investigation. Experimental shooting can be of benefit for autopsy conclusions, because the wounding potential of military weapons differs from that of non-military weapons. Assault rifle gunshot wounds were inflicted upon anaesthetised swine from various distances and angles and with variable shielding of the skin. The morphology of the skin wounds was studied and post-mortem changes were documented while the wounds were being observed in cool and room temperature conditions for 13 days. Large variation was found in the size, form, and regularity, and in the presence and width of the abrasion zone of entrance and exit wounds, in addition to secondary wounds. The maximum diameter of entrance wounds varied between 4 and 40 mm and that of exit wounds between 10 and 110 mm. The width of the abrasion zone surrounding entrance wounds ranged from 2 to 11 mm. Extreme care and caution are needed when drawing conclusions with regard to cases of multiple gunshot injuries, and especially when post-mortem changes are considerable.