In toothpaste formulated for hypersensitivity, potassium compounds such as potassium nitrate and potassium bromide are often added because it is believed that neurotransmission is blocked by the function of potassium ions. Thus far, we have proposed attaching a hydroxyapatite sheet on dentin as a treatment for hyperesthesia. We think that it may be possible to block dental tubules and relieve pain by adding potassium to the sheet for sustained release. In this study, we prepared and evaluated a potassium-doped hydroxyapatite thin film, and applied the process to the preparation of a potassium-doped hydroxyapatite sheet.