A secondary ion mass spectroscopic study of the elemental composition pattern in rat incisor dental enamel during different stages of ameloblast differentiation.

In most earlier studies on the elemental composition pattern of dental enamel, a picture is presented which describes a limited region. In this study, estimates of the incorporation of some critical elements into enamel were correlated with the differentiation stages of the ameloblasts through out the whole tooth. Elemental analyses of rat incisor dental enamel during the secretory, transitional and maturation phases were performed using two different modes of secondary ion mass spectrometry (SIMS). The results were presented as ion images and three-dimensional spatial resolution graphs. In the elemental images of 23Na, 26CN, 35Cl and 39K, counts were detected during the secretory and maturation phases of amelogenesis. Variations were interpreted as resulting from secretion of elements during the secretory phase and resorption during the maturation phase. In line scans the ion yield from enamel during different stages of differentiation of the ameloblasts was analysed. The elements investigated were 12C, 19F, 23Na, 31P, 39K and 77CaCl. As seen in the images, most elements exhibited a higher ion yield during the earlier stages of secretion, and lower yields during the maturation-phase resorption. Cl, together with P, increased during the phases of maturation. In the most apical portions of the teeth, corresponding to a presecretory phase, an inverse pattern was seen for most of the elements. If the surface yield was high at the onset of the secretory phase, the presecretory yields were lower, and vice versa.

Dental conditions and temporomandibular joints in an early mesolithic bog man.

In 1994 parts of a human skeleton were found in the county of Västergötland, Sweden. The remains were probably from a man and estimated according to 14C dating to be about 9800 years old, i.e. from the Early Mesolithic Period. As such old finds are rare and the skull was well preserved a more detailed description is presented in this paper. The facial skeleton was robust and the face shape was rectangular. The remaining teeth, one maxillary and 10 mandibular teeth, exhibited no caries but extensive occlusal wear which in some teeth had exposed the pulp and led to periapical osteitis. Besides these teeth the 4 maxillary incisors and the two canines and one incisor in the mandible had been lost post-mortem, probably because of severe marginal bone loss. Both temporomandibular joints showed remodelling, one also osteoarthrotic changes. The observations are discussed with respect to masticatory function and some background factors.

Denture marking. Clinical and technical aspects.

The frequency of edentulousness has decreased in recent years due to the improvement in oral health. However, there is still a need to address the issue of denture marking for social and legal reasons because the oral status of populations varies in different countries and the wearing of complete dentures will be a fact for the foreseeable future. Given that only one marked denture can tell us the identity of a decreased when all other methods fail makes it a worthwhile exercise. The marking of dentures is not regulated by law in Sweden, but it is recommended by the Swedish Board of Health and Welfare (SOSFS[M]1986), that all patients should be offered the opportunity to have their dentures marked, which they may refuse. In Sweden, the dental laboratories report that they mark all dentures. The Swedish ID-Band has become the international standard and FDI accepted denture marking system, but recent research has indicated that this metal band is not resistant to very high temperatures. Since there is no international consensus regarding the matter we suggest that new materials should be explored.

The use of the stable isotope 44Ca in studies of calcium incorporation into dentin.

The incorporation into rat incisor dentin of two calcium isotopes, the stable 44Ca and the radioactive 45Ca, was studied using secondary ion mass spectrometry (SIMS) step-scanning and imaging, and autoradiography, respectively. The results demonstrated a time-dependent incorporation of the calcium isotopes into the mineral phase of dentin. With the SIMS step-scanning, detecting 44Ca, the ion yield was high in the odontoblasts 2 min after intravenous injection. After 10 min a marked increase in signal intensity was found at the dentin mineralization front. This result was consistent with those obtained by 45Ca autoradiography; a peak of incorporation occurred 10 min after injection of the isotope. Likewise, localization of 44Ca to the mineralization front could be demonstrated 10 min after injection by SIMS imaging. In images obtained at earlier intervals, no such increase in ion yield could be detected. The results show that the nonradioactive, stable isotope 44Ca can be used as a marker for biomineralization in a similar way to radioactive 45Ca.

The absence of correlations between a clinical classification and ultrastructural findings in amelogenesis imperfecta.

This study was performed to examine whether a clinical classification of different phenotypes of amelogenesis imperfecta could be discernible at the ultrastructural level. Seventeen primary teeth from 16 children with hypomineralization, hypomaturation, or hypoplastic variants of the disease were collected for histologic studies of the enamel by means of polarized light microscopy, scanning electron microscopy (SEM), and secondary ion mass spectrometry (SIMS). Polarization microscopy showed that the enamel was hypomineralized; in six teeth a wavy configuration of the enamel prisms also appeared. Three histomorphologic main types could be discerned. In 10 of the teeth extensive hypomineralization of the bulk of the enamel was found. One tooth had an unusually thick enamel with only a thin normally mineralized surface layer. SIMS images showed less pronounced signals from Ca2+ and Na+ but with stronger signals from Cl- and CN-, representing the organic component of enamel. The SEM images showed an irregular prism pattern with marked interprismatic areas. Irrespective of the clinical appearance or the hereditary pattern the main findings were hypomineralized enamel with or without wavy bands. Neither of the analytical methods used in this paper distinguishes between the clinical phenotypes of amelogenesis imperfecta.