**2.1.4 Result**

54 Macro to Nano Spectroscopy


The rate of potassium chloride clearance from the gels into a large, stirred volume was determined. One involved suspending the filled chambers in one liter of 100 ppm NaCl, stirred by a magnetic stirrer, either at room temperature or at 37℃. The diffusion chambers were taken from the fluid at selected time intervals and the gels transferred quantitatively with a sewing needle to flasks containing 500 ml of 100 ppm sodium chloride. The fluid was agitated intermittently for 90 min, since preliminary studies showed that the remaining potassium chloride was extracted from the gel in this time interval. The potassium concentration was also measured in identically prepared agarose discs which had not been

A least-squares straight line was fitted, by computer, to the potassium concentration plotted against the square root of time. This gives a very good approximation of the theoretical clearance curve until about 65% of the diffusant has been lost from the gel (see 2-1-5). From

The subjects were 6 adults with a mean age of 26 years. They had a complete dentition up to

 Seven different sites in the mouth were chosen for measurements. These were the Lower anterior lingual (LALi) and buccal (LAB), lower posterior buccal (LPB) and lingual (LPLi), upper posterior lingual (UPLi) and buccal (UPB), and upper anterior buccal (UAB). The flow rate of unstimulated whole saliva was measured on each occasion for 5 min by being

Fig. 4. Acrylic chamber attached to the upper central incised

put into the 100 ppm NaCl, to give the initial concentration.

allowed to drip off the lower lip into a weighed container.

& Dawes, 1987) for clearance.

the results, the half-time was calculated.

the second molar and no malocclusion.

**2.1.3 Subjects and locations** 

The half-times in the mouth varied with locations and with salivary flow rate, as shown in Fig. 5 When the flow rate was unstimulated, the shortest halftimes occurred in the LALi site and the longest in the UAB site. In both groups, the difference was significant at p<0.001.

Fig. 5. Half-time when salivary flow rate is unstimulated
