**2.3. Vibrotactile stimuli on the parotid and submandibular glands**

time from the previous experiment [2]. We carried out the examinations and used 19 normal subjects (male: 6 and female: 13, average age 22) for the resting-stimulating examination. This

*Second, as shown in* **Figure 2**, *we used three different frequencies (89, 114 and 180 Hz) and two different amplitudes (1.9 and 3.5 μm) on the parotid and/or submandibular glands. Amplitudes of vibrotactile stimuli were measured by the CCD laser displacement gauge (LK-G3000, KEYENCE Co.). After three different frequencies were attempted on the parotid glands, we explored the most effective frequency, and we arrived at a frequency of 89 Hz. We examined the frequency of 89 and 114 Hz and we used also oscillating bodies added as the frequency with double motors (one motor is 1.9 μm amplitude and double motors is 3.5 μm amplitude). Namely, the second experiment was practiced by 89 and 114 Hz with one motors (1.9 μm amplitude), and 89 and 114 Hz with double motors (3.5 μm amplitude). We examined the amount of salivation in four different trials, as shown in* **Figure 2***. We carried out the examinations and used 17 normal subjects (male: 15 and female: 2, average age: 22) for the resting-stimulating examination. This experiment was performed between 3 and 5 pm in a* 

Finally, as shown in **Figure 2**, since the most effective salivation by vibrotactile stimuli was at 89 Hz frequency with one motor (1.9 μm amplitude), we examined salivations on 89 Hz vibrotactile stimulation *continuously for* 4 or 5 days. *As patients continuously utilized the apparatus, we examined if adaptation develops with everyday usage and whether or not the decrease of salivation arises*. We investigated the adaptation of periods with the continuous use of vibrotactile stimuli for 4 continuous days in the same subjects. We carried out *this examination* and used 26

experiment was performed between 3 and 5 pm in a temperature-controlled room.

*temperature-controlled room.*

108 Salivary Glands - New Approaches in Diagnostics and Treatment

**Figure 2.** Salivations in each vibration frequency.

As shown in **Figure 1**, we examined the difference between vibrotactile stimuli on the parotid glands and the submandibular glands. First, we tried three different vibrotactile stimuli, 89, 114, and 180 Hz, on the parotid glands and explored the frequency for the most effective salivation, as shown in **Figure 2**. Next, we inferred the most effective salivation of 89 Hz with the one motor depending on vibrotactile stimuli on the parotid or submandibular glands [2]. Furthermore, we investigated the most effective salivation depending on the difference of amplitudes (1.9 and 3.5 μm amplitudes). We inferred the most effective salivation of 89 Hz with the one motor (1.9 microm amplitude) on the submandibular glands (significant difference *P* < 0.05, 89 Hz with 1.9 μm amplitude and 114 Hz with 1.9 and 3.5 μm amplitude), as shown in Hiraba et al. [2].

### **2.4. Total salivation after the vibrotactile stimulation on the parotid or submandibular and sublingual glands**

In 89 Hz vibrotactile stimulation with 1.9 μm amplitude on the parotid glands, we observed the most effective salivation in each gland, the right parotid, left parotid, right submandibular and sublingual, and left submandibular and sublingual glands. *Vibrotactile stimuli on the parotid or submandibular glands in any case showed that at 89 Hz more effective salivation in the right and left parotid and in the left and right submandibular and sublingual glands happened in comparison with the resting salivation in each gland.* On the other hand, vibrotactile stimuli with 1.9 μm (89 and 114 Hz—1) or 3.5 μm amplitudes (89 and 114 Hz—2) on the parotid or submandibular glands were examined. The 89 Hz with one motor, was the most effective salivation in the parotid, and the submandibular and sublingual glands, and the 89 Hz with double motors, was the more effective salivation in the parotid, and submandibular and sublingual glands, as shown in Hiraba et al. [2]. From these reasons, we suggested that vibrotactile stimulation at 89 Hz with 1.9 μm amplitude showed the most effective salivation in many glands.

Finally, we assumed that 89 Hz with 1.9 μm amplitude vibrotactile stimulation *produced the most effective salivation,* and then the vibrotactile stimuli on the parotid and submandibular glands *showed* hardly any difference. We then decided to use the apparatus to patients affected by poor salivation.
