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ePaper created 2016-09-20, 16:58:27 | version 1.38.0
Journal of Oral Science & Rehabilitation Volume 2 | Issue 3/2016 65 i n v i t r o s t u d y o n v i s c o s i t y teeth and lubrication of the oral cavity. Salivary viscosityisassociatedwiththeamountofmucin; both these factors are also associated with the degree of periodontal disease and clinical symp- toms.2 Thephysicalpropertiesofsaliva,including flow, pH, buffering capacity, and viscosity, have been found to be associated with caries activity in children and to act as markers of caries.5 Xe- rostomia patients are knownto have lowsalivary flow and high viscosity compared with healthy individuals.6 For the maintenance of a complete denture,thephysicalpropertiesofsalivabetween the base of the denture and the mucosa under thebaseareconsideredimportant,andthusthere are many studies on the viscosity of saliva and maintenance of dentures.7 Determining the amount and condition of saliva at the chairside with ease is important for improvement of oral function and the intra-oral environment, eating and swallowing support, and increased quality of life. Viscosityhaspreviouslybeenmeasuredusing capillaryflowmethodsorrotationalviscometry.17 Capillary flow methods are simple to operate, requireashortmeasurementtimeandareaccura- te. However,whentheviscosityofa non-Newto- nian fluid is measured, only the mean value is obtained, because the shear rate varies, depen- ding on the location within the viscometer.10–12 Generally, in rotational viscometry, a constant, that is the shear rate, allows for a constant, uni- form flow in all locations in the viscometer. This canbeusedtomeasuretheviscosityofnon-New- tonian fluids; however, the equipment is compli- cated and measurement requires 20–30 min. Furthermore, it has inferior precision compared with capillary methods, and it is not suitable for low-viscosity fluids.16, 17 A large amount of saliva is needed, and intake saliva needs to be filtered, eliminatinglargepolymersandmakingitdifficult to reflect the exact properties of saliva. Procedu- res such as equipment cleaning are complex and time-consuming, and the equipment is costly. In addition, with a conventional viscometer, a low torque is generated, making it difficultto measu- re a low-viscosity sample. A cone-plate viscometer can analyze small samples (2–3 mL). However, it is not suitable for Figs. 2 & 3 Fig. 2 Viscometer reproducibility using a viscosity standard fluid. Fig. 3 The measurements using different disposable test tubes and spheres with the viscosity standard fluid. Fig. 4 The measurements using different amounts of viscosity standard fluid. Fig. 5 Viscometer reproducibility using Saliveht. Figs. 4 & 5 Volume 2 | Issue 3/201665