The objective of this study was to obtain information on the mineralisation patterns within calculi from images of their internal structure. 3D images were obtained using; non-destructive X-ray microtomography (XMT) to visualise the internal micro-architecture, and confocal microscopy (CM) to examine surface characteristics, of a number of salivary calculi.
Methods: Submandibular calculi were collected from 20 patients, and placed in 1 cm diameter plastic tubes containing deionised water. Each tube was positioned onto the XMT apparatus and projection data collected over periods of up to 24 h. XMT datasets were reconstructed to obtain images at a resolution of 15.71 mm. The XMT image files were between 0.25 and 1.25 Gbytes. The XMT images were analysed using 3D visualisation software to reveal the internal structure of all of the specimens. Confocal microscopy was used at wavelength 543nm to construct z series of the surfaces.
Results: The XMT images revealed three different types of mineralisation pattern within the salivary calculi. Type 1 was highly mineralised, and quite dense. Type 2 was lamellar in structure. Type 3 showed no apparent organised structure. Most calculi demonstrated at least two types of mineralisation pattern, often with Type 1 at the centre. However, some calculi demonstrated only Type 1 mineral pattern, and others only Type 3.
Conclusions: The different mineralisation patterns within the internal structure of salivary calculi suggests a range of different of biomineral deposition processes. The common feature of microglobuli and globuli of calcified material suggest that these are not necessarily based on organic foci but represent a form of calcification proceeding in a mucoid matrix.
Acknowledgements: EPSRC Grant No. GR/R28911/01