Computational fluid dynamics analysis of salivary flow and its effect on sialolithogenesis

Abstract

OBJECTIVE Sialolithiasis is a common disease caused by intraductal stones, formed by reduction in salivary flow, salivary stagnation, and metabolic events. We used computational fluid dynamics to investigate changes in salivary flow field around parotid stones of different shapes. MATERIALS AND METHODS Three-dimensional configurations of the Stensen’s duct were reconstructed from computed tomography sialographic images. Fluid dynamics modeling was used to analyze the salivary flow field around stones under unstimulated and stimulated conditions. RESULTS The majority of sialoliths were oval-shaped (59/98), followed by irregular (24/98) and round (15/98). Salivary velocity was significantly higher around streamlined stones, compared with round (P = 0.013) and oval (P = 0.025) types. Changes in salivary flow field around sialoliths were found to affect the pattern of mineral deposition in saliva. The area of low velocity around the round stone was double the size observed around the streamlined stone during the unstimulated state, whereas in the stimulated state, local vortexes were formed on the downstream side of round and oval stones. CONCLUSIONS Salivary flow field around sialoliths plays an important role in the progression of multicentric stones, and analysis of the salivary dynamics during sialolithiasis may provide deeper understandings of the condition and aid in developing successful treatment strategies.

Role of the Accessory Parotid Gland in the Etiology of Parotitis: Statistical Analysis of Sialographic Features

“…Zhu et al explored the effect of salivary flow on sialolithogenesis using computational fluid dynamics analysis. They demonstrated a low velocity zone and a vortex zone forming around sialoliths, which exacerbated their development [ 20 ]. We speculate that if there is a special flow field in the confluence of the AD with SD, this could block salivary flow and led to the increased risk of parotitis.…”

Mineralization of Sialoliths Investigated by Ex Vivo and In Vivo X-ray Computed Tomography

“…6), or asymmetrical (S 9 in Fig. 6) shapes (Zhu et al, 2014), while the internal structure shows growth patterns ranging from quite concentric (e.g., S 7 ) to rather irregular (e.g., S 14 ) (Nolasco et al, 2013).

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“…The sialoliths’ geometry, nearly spherical, oval, or highly asymmetrical (Zhu et al, 2014) (Fig. 6), is associated with the anatomical location (Seldin et al, 1953).…”

“…Most of the specimens investigated in the present study had relatively high aspect ratios ( Ar > 2) (Table 3), consistent with the geometric constraints in the ducts of salivary glands (Seldin et al, 1953). In addition, the mineralization process of sialoliths is conditioned by the flow dynamics of saliva at their surface (Zhu et al, 2014). Regardless of the calculi morphology, low-velocity regions are formed near the calculi anterior and posterior surfaces (Zhu et al, 2014).…”

“…In addition, the mineralization process of sialoliths is conditioned by the flow dynamics of saliva at their surface (Zhu et al, 2014). Regardless of the calculi morphology, low-velocity regions are formed near the calculi anterior and posterior surfaces (Zhu et al, 2014). This effect enhances the local precipitation of Ca 2+ , PO 4 3− , and Mg 2+ and results in an anisotropic elongation of the calculi in the saliva flow direction (Zhu et al, 2014).…”