The morphology of salivary calculi. A scanning electron microscopic study.

Salivary calculi are a common disorder in the submandibular gland duct system, but the etiology and pathogenesis of the concrements remain unclear. Ten submandibular gland calculi were examined in a scanning electron microscope after critical-point drying, fracturing, and gold coating. The surface of the calculi was built up of numerous knobs covered by a smooth and occasionally filamentous substance, probably of mucinous origin. Microorganisms were commonly found at the surface. The nuclei of the calculi, which were rather homogeneous, were surrounded by lamellated structures. Between the lamellae spheroid bodies, 20-100 microns in diameter, were present. These spheroid bodies are probably of mucinous origin, which together with an amorphous granulated substance builds up the matrix. Microorganism-like structures occasionally appeared at the interface between lamellae. Microorganisms can be an important factor by providing an organic matrix in the later phase of the pathogenesis of salivary calculi. However, the nuclei did not show morphological evidence of any particular factor explaining the etiology of salivary calculus.