The aim of this study was to examine electron microscopic features of canalicular concretions obtained from patients with canaliculiths.
Canalicular concretions were obtained from 10 patients diagnosed as canaliculiths and were immediately fixed for ultrastructural analysis. Surface structure and transmission electron microscopical sections were studied. Multiple longitudinal and transverse ultrathin sections were obtained at different levels and all were studied using standard protocols of scanning electron microscopy and transmission electron microscopy.
Three different types of canalicular concretions were noted; predominantly coccoid and bacilloid, predominantly filamentous, and mixed varieties. The surfaces and the cut sections showed typical and distinctive features for each of the concretion types. The filamentous subtypes were common accounting for 50% (5/10) of all canalicular concretions. The surface of predominantly filamentous concretions revealed typical honeycomb patterns, the walls and base of which were formed by definitive and peculiar arrangement of Actinomyces. Transmission electron microscopy confirmed the findings of scanning electron microscopy and demonstrated typical structural features of Actinomyces and some other bacteria undergoing binary fission. The most interesting feature was the lack of immune cells and blood products within the substance of canalicular concretions as compared with the mucopeptide concretions.
Ultrastructural features of canalicular concretions reveal 3 distinct microbial subtypes and opens up avenues toward better understanding of the etiopathogenesis of canaliculiths and possible structural resistance to host defenses or antibiotics.