Spectroscopic and Microscopic Characterisation of Parotid and Submandibular Ductal Sialoliths: A Comparative Preliminary Study

Abstract

Sialoliths, the calcified structures that develop within the salivary gland parenchyma and its ductal system, are the major cause of acute and chronic sialadenitis. Various theories of aetiology have been postulated, yet unclear. Aim of our study is to study the submandibular and parotid ductal sialoliths ultra-structurally and chemically to derive its respective mechanism of lithogenesis. Two parotid and a submandibular intraductal sialoliths were retrieved from sialadenitis patients, and each was analysed using high-resolution scanning electron microscope, energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy and compared with each other. Scanning electron microscopic analysis of parotid sialoliths revealed irregular scaly pattern of rudely spike-like crystals with tubular porosities which might suggest earlier harbour of bacilli, whereas submandibular sialolith revealed globular, roughly rhombohedral crystals with spherical intercrystal porosities. From EDS analyses, it was evident that levels of calcium and phosphorus found to be three times more in submandibular sialolith than parotid sialolith. FTIR spectroscopic analysis showed more hydroxyl vibration spectra in submandibular sialolith, whereas parotid sialolith showed more amide and CO stretching. Above results suggest that the submandibular sialoliths are composed mainly of inorganic contents while parotid sialoliths predominantly with organic contents. Henceforth, chronic sialadenitis and morpho-anatomical disadvantage of ductal orientation plays a major role in the submandibular sialolith formation while organic nidus in the parotid sialolithogenesis.