Development of caries sicca in a dry calvaria

Summary

This study of the development of the bone changes in caries sicca was based upon the microscopy of over a hundred serial sections from eleven undecalcified blocks from a dry calvaria. In the absence of cells much depended upon the distribution of the mineral, the pattern of the collagen fibre bundles, the size, shape and arrangement of the vascular and osteocyte spaces, and of canaliculi. Examination by polarized light and microradiography was used. Mineral redeposition was not seen [3].

The changes observed had all occurred as relapses of active disease in a previously inflammed and now sclerotic bone. It is possible, however, to propose the changes that occur and the sequence of their development.

The first change is an inflammatory osteoporosis which starts in the deeper part of the outer table of the calvaria (Fig. 13). This spreads in all directions in the diplöe to form the destructive focus, up to 30 mm in diameter. As the inflammatory reaction subsides, fibre-bone fills the holes in the middle of the focus and follows the outward spread of the osteoporosis. This is then remodelled through further osteoporosis and lamellar bone filling until the whole focus becomes sclerotic bone in which some fibre-bone may persist. The characteristic multi-nodulation arises from localized periosteal and diplöeal bony enlargements.