Ultrastructure of the predentinal-dentinal border zone of human teeth exposed to basic chromium (III) sulfate. A method for contrasting of collagen fibrils.
An electron microscopic investigation was undertaken to study a method for contrasting predentine collagen fibrils by their cross-striations after exposure of tissue to chromium solution for various periods. After 1 day of treatment, the cross-striations of collagen fibrils in predentine were clearly visible. The contrast of the cross-striations increased with longer periods of exposure to chromium. This method makes it possible to study the orientation of crystallites as well as collagen fibrils.
A new technique for decalcifying thin ground specimens of adult human enamel.
Abstract A new decalcification technique is described for the recovery of the organic matrix from thin ground specimens of adult human enamel. An aqueous solution of chromium sulphate which has both fixing and decalcifying properties is used. The results are compared with those obtained when an adjacent part of the same ground specimen was decalcified with the hydrochloric acid solution of Brain (1962). Dependent on slight differences in pH of the chromium solutions, two different appearances of the recovered matrix are obtained: above pH $ 3.2 a structural matrix which is positively birefringent at refractive index 1.55, whereas below this pH a matrix which is homogeneous and non-birefringent and almost similar to the matrix obtained after hydrochloric acid decalcification. The two types of matrices are discussed and the one favoured on morphological grounds, the chromium sulphate structural matrix, is related to present concepts of the structure of the native enamel matrix.
A new method for the preparation of decalcified sections of human enamel in situ.
Abstract A simple technique suitable for the preparation of decalcified sections from human material is described. A slice from a tooth and supporting bone 4 mm in thickness is decalcified in a solution of 4 N sodium acetate hydrochloric acid buffer, pH 3.5, and subsequently embedded in paraffin wax. With this method it is possible to preserve a considerable proportion of the enamel. Both the enamel and cellular elements stain deeply with haematoxylin, enabling them to be observed and studied at varying magnifications.