Effects of Abrasives on F Deposition by Fluoride-Calcium-Phosphate Slurries

Objectives: Oral rinses containing a stable fluoride-calcium-phosphate (FCP) complex were previously reported to deposit significantly greater F amounts in the mouth in vivo and on tooth surfaces in vitro. OBJECTIVE: To determine the effects of abrasive particles on F deposition by FCP slurries.
Methods: METHODS: All FCP slurries contained 87.7mM NaF, 146mM CaCl₂, and 14.6mM H₃P0₄, and 77.3 g/L of one of the abrasives: (1) Zeodent 113, (2) PVA coated Zeodent 113, and (3) calcined alumina. The F and abrasive contents of the slurries corresponded to a 3-fold diluted 5000 ppm F dentifrice. For each abrasive, both freshly prepared and 1-d old slurries were tested. F deposition was measured using a previously established in vitro mode (Takagi et al Caries Res 2001).
Results: RESULTS:
Treatment slurry F deposition, µg/cm²
(mean±std; n=3)

FCP + Zeodent (fresh) 9.0±0.2
FCP + Zeodent (1-d old) 1.9±0.1

FCP + PVA coated Zeodent (fresh) 10.6±1.0
FCP + PVA coated Zeodent (1-d old) 1.9±0.1

FCP + Calcined alumina (fresh) 21.0±1.1
FCP + Calcined alumina (1-d old) 16.1±0.3

All freshly prepared FCP slurries deposited significantly higher amounts of F than that (2.2±0.4 µg/cm²) produced by an NaF slurry of the same F content. However, the 1-d old slurry containing either the uncoated or PVA coated Zeodent produced much lower F deposition. On the other hand, the 1-d old alumina containing slurry continued to produce significantly higher F deposition. FCP was shown to decompose and precipitate CaF₂ when in contact with “active” surfaces including teeth and mucosa. Current results indicate that Zeodent surfaces were sufficiently active for FCP decomposition, rendering the slurry ineffective in producing high F deposition, while alumina appears more compatible with the FCP.
Conclusions: CONCLUSIONS: FCP may be suitable for formulating dentifrices with improved F deposition providing a compatible abrasive system is used. Supported by ADAF and NIST.