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Using zircons taken from two granite plutons, Strontian (Caledonian, northwestern Scotland) and Kameruka (Bega Batholith, southeastern Australia), this study presents observations that have a bearing on refractory zircons as provenance indicators. Two broad textural types of refractory zircon were identified: (1) those which show simple two-stage growth histories; and (2) those which have apparently undergone repeated periods of growth, resorption, mechanical abrasion, fracturing and fracture-healing. SHRIMP U-Pb ages obtained from the Kameruka zircons indicate that the cores are the textural manifestation of inheritance. The shapes of refractory cores are not unambiguously indicative of their ultimate origin, since they may also be modified by processes that occur before and after incorporation into the magma. The cores within the two populations show a great diversity in types and styles of zoning, and in composition, implying that they have not chemically equilibrated internally, or externally with their host melt.

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Accessory minerals are often difficult to investigate with light optics as the mineral grains tend to be small and the refractive indices high. Textural features due to variations in composition are well displayed in such minerals by backscattered electron imagery under circumstances designed to select only the composition contribution to electron backscattering and displayed as atomic number (Z)-contrast imagery (ZCI). It is shown by this technique that compositional zonation patterns are very common and sector zoning in titanite is described for the first time. The compositional basis for zonation of titanites in this study is shown to be controlled by coupled substitutions involving the REE. The technique is particularly good at revealing rounded cores to zircon grains which are normally taken to be refractory grains from the magma source region, and ZCI studies may improve targeting of grains for U-Pb geochronological investigations. Several examples are presented of applications of the technique to accessory minerals encountered in polished thin sections of granitoids in the Caledonian of Scotland. The consequences of ZCI studies for trace element modelling of REE in granitoid petrogenesis are discussed.

The use of a resin-based glass ionomer as an endodontic sealer was studied in vitro. The root canals of extracted single-rooted human teeth with mature apices were prepared using a stepback technique. Subsequently, the smear layer was removed with 40% citric acid and the canals obturated using lateral condensation of cold gutta-percha and a resin-based glass ionomer as the sealer. The relationship between the sealer and the wall of the root canal was studied using scanning electron microscopy. The shear bond strength of gutta-percha to this glass ionomer was also determined. Finally, the uptake of fluoride into the wall of the root canal was studied using scanning electron microprobe analysis after storage for 2 weeks, 1 month and 3 months following root filling with gutta-percha and glass ionomer cement. The results showed that removal of the smear layer allowed the sealer to enter some of the dentinal tubules. This was observed most frequently in the middle third of the root canal, where there was good adaptation of the sealer. The shear bond strength of gutta-percha to the glass ionomer sealer was not significantly different from that obtained between gutta-percha and a proprietary zinc oxide-eugenol endodontic sealer. The concentration of fluoride in the dentine in the coronal part of the root canal increased after obturation with gutta-percha and the glass ionomer sealer at every time interval. The increase in fluoride concentration varied widely between teeth. It is concluded that a resin-based glass ionomer cement may have potential as a root canal sealer.