Three-dimensional photo-elastic stress analysis of maxillary and mandibular complete dentures

Three-dimensional photo-elasticity was used to study the stress distribution in complete dentures in functional positions. A new loading device was developed utilizing a linear motion bearing as its main component and mandibular dentures were evaluated for the first time. The stress concentrations were highest (2.5 fringes) on the working side of the mandibular denture. This was also demonstrated in the maxillary denture; however, the magnitude was less (1.8 fringes). The results indicate that this method could be used to quantitatively evaluate the effect of various occlusal schemes upon the denture bases.     

Quantitative analysis of histological parameters in giant cell lesions of the jaws and long bones

Stereological techniques have been used to compare histological parameters of the giant cell component in 10 giant cell tumours of long bones, 10 central giant cell granulomas of the jaws and 10 peripheral giant cell granulomas of the jaws. The giant cell parameters investigated were: mean profile diameter, mean diameter, mean profile axial ratio, volume-to-surface ratios, nuclear numerical density, profile area and cell volume. Serial sections were cut at 4 micron from routinely fixed, paraffin-embedded specimens of each case and two sections, separated by 100 micron, were stained with haematoxylin and eosin. Random fields were photographed until at least 25 giant cell profiles had been recorded from each of the two sections of each lesion. The processed film was projected for point and intersect counting, the entire procedure ensuring double-blind assessment of the cases under investigation. In general there was no significant difference for any of the parameters between the giant cells of central and peripheral jaw lesions. There was a significant difference, however, between the giant cells of central jaw lesions and long bone tumours in respect of both nuclear numerical density and mean absolute cell volume.