Fluoride compounds are major substances that inhibit the growth of oral bacteria, increase the hardness of the
tooth surface, and promote recalcification. However, caution must be exercised regarding fluoride exposure, as
it may cause side effects to the human body due to its toxicity if swallowed. Accordingly, this study was conducted
to evaluate the residual amount of fluoride remaining in saliva after using mouthwashes containing high
and low fluoride concentrations. After rinsing with five commercially available high-fluoride mouthwashes
according to the manufacturer’s instructions, the fluoride concentration remaining in saliva was quantitatively
evaluated over time through Fluorine (19F) NMR (magnetic field: 9.4 Tesla) immediately, 1 minute, and 2 minutes
later. When gargling with DH 2000 ppm fluoride, the residual salivary fluoride content was 30.3960%
immediately after gargling, 0.0041% after 1 minute, and 0.0020% (0.0401 ppm) after 2 minutes; when gargling
with EB 1000 ppm, it was 16.5001 % immediately after gargling, 10.6269 % after 1 minute, and 0.0034%
after 2 minutes; and when gargling with BS 1000 ppm, it was 17.1169 % immediately after gargling, 13.2337%
after 1 minute, and 0.0019% (0.0188 ppm) after 2 minutes. When gargling with LIS 220 ppm, the residual salivary
fluoride content was 56.3716 % immediately after gargling, 0.0842% after 1 minute, and 0.0180%
(0.0396 ppm) after 2 minutes; and when gargling with R 90 ppm, it was 0.0302% immediately after gargling,
0.0151 % after 1 minute, and 0.0077% (0.0069 ppm) after 2 minutes. Even when mouthwashes containing various
fluoride concentrations were used, only the fluoride content of existing normal saliva remained after 2 minutes,
confirming that swallowing the saliva is safe and does not affect the human body.