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Journal of Oral Science & Rehabilitation No. 3, 2016

Journal of Oral Science & Rehabilitation Volume 2 | Issue 3/2016 63 i n v i t r o s t u d y o n v i s c o s i t y Introduction Saliva is mainly secreted by the three major sal- ivary glands: the parotid, submandibular and sublingual glands. The saliva secreted from all three glands mixes in the oral cavity and exerts physiological functions. Saliva has important bacteriological, biochemical, and physicaleffects on the inside of the mouth, and is relevant to studies in many different fields. In particular, the viscosity of saliva is mainly responsible for the lubricating action that aids inthe movement ofthetongue and lips. It is also essential for ingestion, swallowing, speech and other functions.1 Salivary viscosity is correlated with periodontal disease,2, 3 dental caries4, 5 and xerostomia,6 and plays a role in the mainten- ance and stability of dentures;7–9 therefore, it is an important research topic. Various rotational viscometers and capillary viscometers have been usedto measure salivaryviscosity, butthey are not easy to use and require large amounts of saliva.10–17 Theelectromagneticallyspinning(EMS)visc- ometer, developed bySakai et al. in 2008,18 uses a minute metal sphere of approximately 2 mm in diameter submerged in a sealed sample and subjected to electromagnetic induction, which is a remote operation that applies rotational torque. In this newsystem, theviscoelasticityof a substance is assessed bya camerathat records the rotational movement of this sphere. This method uses disposabletubes and spheres, pre- venting the possibility of infection. The use of this device might make the chairside measure- ment of salivary viscosity simple. To the best of our knowledge, no report has examined the reproducibility of this device. The aim of the present study was to evaluate the reproducibility of measurements of salivaryvis- cosity using an EMS viscometer. Materials and methods AnEMSviscometer(KyotoElectronicsManufac- turing, Kyoto, Japan) was used to measure vis- cosity (Fig. 1). An amount of 300 μL of a viscos- ity standard fluid (Showa Essential Oils, Tokyo, Japan) was poured into the test tube, the sphere submerged, and the test tube covered with a sealed cap and inserted into the device. The thermostatic bath in the device was set to 36 °C and a rotational speed of 1,000 rpm. Once the temperature of the viscosity standard fluid had stabilized, measurements were taken. All mea- surements were repeated five times at 30 min intervalswithinthe same dayusingthe same set of tubes, spheres and viscosity standard fluid. We prepared five different sets oftest tubes, spheres and viscosity reference solutions. A 300 μLaliquotofviscosityreferencesolutionwas addedtothedevice,andfivemeasurementswere taken after the temperature of the solution had stabilized. This procedure was then repeated usingvarious amounts ofviscositystandardfluid (300 μL, 500 μL, 750 μL and 1,000 μL) placed into different test tubes with different spheres, and these spheres were then inserted into the device. Measurements were repeated five times within the same day. R e p r o d u c i b i l i t y w i t h a l o w - v i s c o s i t y s o l u t i o n , S a l i v e h t Asolution of100% Saliveht (Teijin, Osaka,Japan) was used as test. The thermostatic bath inside the device was set at 36 °C and the rotational speed was set at 1,000 rpm. The Saliveht (300 μL) was placed into a test tube and the sphere was immersed in the solu- tion. The tube was then capped with a sealing cap and inserted into the device. Once the tem- perature inside the device had stabilized, the measurements were repeated five times every 30 min using the same sample, the same test tube and the same sphere on the same day. The procedure was then repeated using dif- ferent five sets of tubes, spheres and Saliveht (300 μL), and the measurements were repeated five times within the same day. This procedure was then repeated usingvarious amounts of Sa- liveht (300 μL, 500 μL, 750 μL and 1,000 μL) placed into different test tubes with different spheres, and these spheres were then inserted into the device. S t a t i s t i c a l a n a l y s i s Themeanandstandarddeviationwerecalculated for the data obtained. Results Using the same viscositystandard fluid, test tube and sphere,the results ofthefive repeated meas- urementswithinthe same dayshowed mean and Volume 2 | Issue 3/201663

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