Alkali-soluble fluoride deposition on human enamel exposed to monofluorophosphate-containing toothpastes in vitro.

Enamel specimens from unerupted third molars were treated with the supernatant of monofluorophosphate (MFP)-containing toothpaste slurries in water. Calcium fluoride-like particles were formed on the enamel surface during a 24-h exposure. The globules were soluble in alkali. More particles were seen on enamel treated with a toothpaste containing both MFP and NaF. The experiments showed that the calcium fluoride-like material formed on enamel after treatment with MFP-containing toothpaste probably originates from the free fluoride present in the pastes. The relatively moderate deposition of fluoride may be of clinical significance because the teeth are so frequently exposed to toothpaste. No firmly bound fluoride was found on treatment of enamel with MFP-containing toothpaste.