Biomedical subjects

T Darvann

Publications and source records attributed to T Darvann.

7 recordsLinked to original sources

PubMed2000

Quantitative ultrasound image analysis of the supraspinatus muscle.

OBJECTIVE: To develop and validate a method, based on quantitative ultrasound image analysis, to objectively analyse and characterize the ultrasound images of m. supraspinatus. DESIGN: Quantitative ultrasonography was performed on the supraspinatus muscle of 14 healthy subjects. METHODS: A computerized analysis using first-order grey-scale statistics to evaluate the muscle tissue composition was developed and validated. RESULTS: Data from one scanning site were not representative for the whole muscle due to muscle inhomogenity. Using first-order grey-scale statistics the scanning direction was of no importance. By using a scanning session consisting of three different scanning sites along the muscle in two directions, longitudinally and transversely, to characterize the tissue composition of the muscle, a high day-to-day reproducibility was obtained. CONCLUSION: The described scanning session is a relatively sensitive and reproducible method for studying the muscle tissue composition. RelevanceQuantitative ultrasonography seems to be a potential clinical and occupational examination method to detect tissue composition of myalgic muscles compared to healthy muscles.

Adult↗

PubMed1999

A computerized analysis of the relation between the occlusal enamel caries lesion and the demineralized dentin.

It has previously been shown that the demineralized dentin does not spread laterally along the enamel-dentin junction in non-cavitated approximal lesions. This study examined the spread of the dentinal part of occlusal lesions along the enamel-dentin junction. The material consisted of 48 well-defined occlusal lesions with histological evidence of dentin demineralization. The teeth were embedded in methylmethacrylate, serially-sectioned, ground, and contrast-stained. The sections with the deepest lesion penetration from each lesion were photographed and scanned by a high-quality scanner in order to produce images for computerized histomorphometric analysis. Two variables were measured on the images: i) the length of the contact area of the enamel lesion along the enamel-dentin junction; and ii) the length of the contact area of the demineralized part of the dentin lesion along the enamel-dentin junction. The results showed a gradual increase in the lengths of the enamel and dentin contact areas between the sections, each representing well-defined progressive stages of lesion formation. In two-thirds of the non-cavitated lesions, the enamel lesion was larger than the demineralized part of the dentin lesion, and in 50% of the cavitated cases the extension of the demineralized dentin was less than the affected enamel. Our conclusion is that the dentin demineralization did not spread significantly in a lateral direction in non-cavitated occlusal lesions.

Coloring Agents↗

PubMed1999

External and internal macromorphology in 3D-reconstructed maxillary molars using computerized X-ray microtomography.

AIM: The aim of this study was to perform a qualitative analysis of the relationship between the external and internal macromorphology of the root complex and to use fractal dimension analysis to determine the correlation between the shape of the outer surface of the root and the shape of the root canal. METHODOLOGY: On the basis of X-ray computed transaxial microtomography, a qualitative and quantitative analysis of the external and internal macromorphology of the root complex in permanent maxillary molars was performed using well-defined macromorphological variables and fractal dimension analysis. Five maxillary molars were placed between a microfocus X-ray tube with a focal spot size of 0.07 mm, a Thomson-SCF image intensifier, and a CCD camera compromising a detector for the tomograph. Between 100 and 240 tomographic 2D slices were made of each tooth. Assembling slices for 3D volume was carried out with subsequent median noise filtering. Segmentation into enamel, dentine and pulp space was achieved through thresholding followed by morphological filtering. Surface representations were then constructed. A useful visualization of the tooth was created by making the dental hard tissues transparent and the pulp chamber and root-canal system opaque. On this basis it became possible to assess the relationship between the external and internal macromorphology of the crown and root complex. RESULTS: There was strong agreement between the number, position and cross-section of the root canals and the number, position and degree of manifestation of the root complex macrostructures. Data from a fractal dimension analysis also showed a high correlation between the shape of the root canals and the corresponding roots. CONCLUSIONS: It is suggested that these types of 3D volumes constitute a platform for preclinical training in fundamental endodontic procedures.

Anatomy, Cross-Sectional↗

PubMed1999

A light microscopic study of odontoblastic and non-odontoblastic cells involved in tertiary dentinogenesis in well-defined cavitated carious lesions.

This study examines cellular and microradiographic findings in thin, undemineralized sections of 46 cavitated lesions, that were clinically well-defined with respect to lesion activity and estimated lesion age at extraction time. The progressive stages of surface breakdown ranged from enamel cavitation to larger dentine exposures classified as closed and open lesion environments. Measurements of the following parameters were performed using computerized image processing software: (a) the cytoplasm:nucleus ratio of primary odontoblast cells; (b) the cell:dentinal tubule ratio; (c) the adjacent predentine area (mum2), and (d) the cytoplasm: nucleus ratio of non-odontoblastic cells, and secondary odontoblast-like cells, where estimation of these cell types were based on structural criteria. In active enamel cavitated lesions, reduced odontoblast-predentine regions and indistinct subodontoblastic regions were noted. During initial dentine exposures, non-odontoblastic cells along the pulp-dentinal interface were observed as well. The first indication of tertiary dentine was seen in old lesions with exposed dentine. The tertiary dentine appeared more atubular in the closed/active lesions than in the open/slow-progressing lesions. The involved odontoblastic cells in tubular tertiary dentine in small open/slow-progressing lesions were comparable to the primary odontoblast cells, however, new dentinal tubules were also noted presenting a mixture between reactionary and reparative dentinogenesis. In close/active lesions non-primary odontoblastic cells were aligning the atubular tertiary dentine, whereas well-defined signs of secondary odontoblast-like cells were first seen in larger open lesions, producing tubular tertiary dentine. In conclusion, a strong relationship between external lesion environments and corresponding different formations of tertiary dentine was noted in advanced cavitated lesions. It is additionally suggested that the stimulation of tubular tertiary dentine could be a closely related reaction when an active lesion complex changes into a slower progressing lesion environment.

Adult↗

PubMed1998

A quantitative light microscopic study of the odontoblast and subodontoblastic reactions to active and arrested enamel caries without cavitation.

This study describes cellular and microradiographic findings in thin undemineralized enamel-dentine sections from 36 enamel caries lesions from freshly extracted third molars. Lesions activity was determined by clinical examination and the estimated age of the lesion at extraction time. The cellular reactions to the enamel/dentine lesion complex were measured using computerized histomorphometry under the following conditions: (a) the cytoplasm:nucleus ratio of the odontoblast cell; (b) the odontoblast cell:dentinal tubule ratio, and (c) the adjacent predentine area (microm2). The first cellular reactions were observed beneath superficial enamel lesions before visible alterations in dentine mineralization. The cytoplasm:nucleus ratio of the odontoblast cells was markedly reduced, and only active lesions showed evidence of cellular proliferation into the cell-free zone. In more advanced active lesions the affected odontoblast cells had a significantly lower cytoplasm:nucleus ratio compared with the controls. Similar changes were not seen in arrested or slow-progressing lesions. Before onset of tertiary dentine formation there was a positive correlation between odontoblast cell size and predentine formation. Primary odontoblast cells were involved in early tertiary or reactionary dentine formation without odontoblast cell replacement. Reactionary dentine was only seen in active lesions, suggesting that reactions in the dentine/pulp complex are closely associated with the external environment.

Adult↗

PubMed1997

Automated image analysis applied to the odontoblast-predentine region in undemineralized sections of human permanent third molars.

A computerized histomorphometric analysis was made by Karnovsky-fixed, hydroxethylmethacrylate embedded and toluidine blue/pyronin-stained sections to determine: (1) the two-dimensional size of the coronal odontoblasts given by their cytoplasm:nucleus ratio; (2) the ratio between the number of coronal odontoblasts and dentinal tubules; and (3) the relation between odontoblast size and adjacent predentine. All conditions were measured in relation to three well-defined sectioning profiles of the dentinal tubules. The sections were randomly taken from 10 unerupted and erupted third-molar crowns. Sixty-three photomicrographs (x100), equally distributed among the three sectioning profiles, were scanned in a high-resolution scanner to produce images for the analysis. After initial user interaction for the description of training classes on one image, an automatic segmentation of the images with respect to odontoblast cell nuclei, cytoplasm and background was computed by statistical discriminant analysis. In longitudinal profiles of the dentinal tubules the cytoplasm:nucleus ratio in erupted teeth was 3.1 +/- 0.54, and the mean of the odontoblast cell:dentinal tubule ration was 1.19 +/- 0.20. Analysis of cytoplasm:nucleus ratio and the adjacent predentine in relation to the chosen sectioning profiles disclosed that there was less variation in the predentine measurements in the longitudinal sections. Thus, in future two-dimensional studies of the odontoblast-predentine region only longitudinal sectioning profiles should be analysed. The use of advanced image processing on undemineralized tooth sections provides a rational foundation for further work on the reactions of the odontoblasts to external injuries including dental caries.

Analysis of Variance↗

PubMedDate not supplied

Anomalies of craniofacial skeleton and teeth in cleidocranial dysplasia.

Mutations involving the transcription factor CBFA1 cause cleidocranial dysplasia (CCD) in man. Recently, a mouse model of CCD has been generated (Cbfal +/-) [Komori et al., 1997], and disturbances of osteoclast differentiation have been documented. It has been shown that these animals exhibit hypoplastic clavicles and nasal bones, and retarded ossification of parietal, interparietal, and supraoccipital bones. Humans with CCD show all these features, including severely retarded ossification of the cranial base, strongly suggesting that both intramembranous ossification and endochondral ossification are affected. In addition, CCD patients have multiple supernumerary teeth and delayed tooth eruption. The present report presents 3D reconstructions of computerised tomography (CT) scans of the craniofacial region of a CCD boy examined at both 1 and 7 years of age. The anomalies in craniofacial skeleton and teeth are analysed and compared to the findings of our previous clinical studies and to the findings in the animal model. Based on the available information, we suggest that osteoblast, osteoclast, and dentinoclast differentiation may be disturbed in CCD.

Child↗