Longitudinal microradiography: a non-destructive automated quantitative method to follow mineral changes in mineralised tissue slices

Presents a new powerful method, longitudinal microradiography (LMR), with which it is possible to follow the mineral content in a de- or remineralising carious tooth sample as a function of position on the surface of the mineralising tissue independent of the sample thickness. Planoparallel tooth slices (thickness 300-400 mu m) are cut parallel to the labial tooth surface and then fixed on a PMMA holder. Repeated microradiographic images of the same tissue slice together with an aluminium step wedge are made on photographic film at different times of mineralisation. The images are scanned under a densitometer with a microcomputer and the mineral content per unit tooth area at the same discrete tooth-slice surface positions is calculated (maximum predefined area is 5 mm*5 mm, 15*15 positions). The change of mineral in one tooth slice per unit tooth surface area can be calculated at different times of mineralisation locally, as well as averaged over the total tooth-slice surface area.