Remineralization potential of 5,000 ppm fluoride dentifrices evaluated in a pH cycling model

Robert L. Karlinsey¹*, Allen C. Mackey¹, Emily R. Walker¹, Bennett T. Amaechi², Ramalingam Karthikeyan², Kaveh Najibfard² and Aaron M. Pfarrer³

¹Indiana Nanotech, LLC, 351 West 10^th Street, Suite 309, Indianapolis, IN 46202, USA.

²University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.

³3M ESPE, 3M Center, St. Paul MN 55144, USA.

*Corresponding author. E-mail: rkarlins@gmail.com. Tel: 317-278-7892.

Accepted 11 December, 2009

   Abstract

Prescription 1.1% sodium fluoride (NaF) dentifrices designed to either have fast dispersion for improved enamel fluoride uptake (that is, PreviDent® Booster 5000) or contain an innovative tricalcium phosphate system for enhanced remineralization (that is, Clinpro® 5000) were evaluated for anticaries potential in an in vitro pH cycling model. Polished bovine enamel specimens were initially softened in a white-spot-forming solution comprising 0.1 M lactic acid plus 100 kDa polyacrylic acid (PAA, pH = 5.0) for 26 h at 37°C.  Specimens were then measured for baseline Vickers microhardness and stratified (N = 12) into the following groups: Group A: Tom’s of Maine fluoride-free dentifrice (negative control); Group B: Colgate PreviDent® Booster 5000 (5000 ppm fluoride) and Group C: 3M Clinpro® 5000 (5000 ppm fluoride). The groups were then cycled for 10 days in a pH cycling model consisting of four one-minute treatment periods (diluted 1:3 with distilled water) and one four-hour acid challenge (lactic acid-PAA , pH = 5.0) per day. Between these events, specimens were immersed in artificial saliva (pH = 7.0). After 10 days of cycling, the specimens were evaluated for Vickers surface microhardness, mineral loss and lesion depth using microindentation, transverse microradiography and polarized light microscopy. For all analyses, statistical differences (t-tests, p<0.05) were found to exist among the groups, with Clinpro® 5000 conferring superior surface and subsurface remineralization potential relative to both PreviDent® Booster 5000 and Tom’s of Maine fluoride-free paste. Due to this superiority, these results suggest the combination of 5,000 ppm fluoride plus the tricalcium phosphate system may provide significant anticaries benefits relative to fluoride-only and fluoride-free dentifrices.

Key words: Dental caries, clinpro 5000, prevident booster 5000, 5000 ppm fluoride, 1.1% NaF,tricalcium phosphate, microhardness, transverse microradiography, polarized light microscopy, pH ycling,remineralization.