Before baseline of application of toothpaste with hydroxyapatite, tooth brushing instruction was done respectively and the several indices were measured at baseline, 2, 4, 8 weeks. Clinical indices were estimated, and responses to cold, compressive air, tactile stimulus were evaluated with verbal rating score. Relief effects and visual analogue scale were also evaluated.

The results of this study were as follows

1. The occurrence rate of hypersensitivity in upper jaw was higher than that of lower jaws, and molar area showed more hypersensitivity than premolar and incisor area. Buccal site was hypersensitive followed by interproximal and lingual site.

2. Plaque index, gingival index and probing depth reduction were gradually improved after Tooth Brushing Instruction and using toothpaste.

3. Subjects showed most sensitive response to cold stimuli than compressive air and tactile stimuli.

4. The relief effect was increased during using tooth paste and complete relief was increased especially at 8 weeks.

5. Visual analogue scale was increased.

In conclusion, it was confirmed that toothpaste containing microcrystalline hydroxyapatite have the relief effect of tooth hypersensitivity. During 8 weeks, stimulus responses were decreased and hypersensitivity relief effect was increased.