This study will evaluate the effect of experimental sodium fluoride-silica dentifrice formulations, with and without zinc, on remineralization of enamel in situ. Following the remineralization phase, the acid resistance of the new mineral formed will be assessed. Fluoride uptake during the remineralization phase will also be measured.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
62
Non-zinc, 1426ppm fluoride as sodium fluoride in a silica gel base
Non-zinc, 1150ppm fluoride as sodium fluoride in a silica gel base
Non-zinc, 250ppm fluoride as sodium fluoride in a silica gel base
GSK Investigational Site
Indianapolis, Indiana, United States
Percentage Surface Microhardness Recovery (% SMHR)
Changes in the mineral content of the four centrally-located enamel specimens were evaluated using the Surface Microhardness (SMH) Test. The SMH was measured using a Wilson 2100 Hardness Tester. The baseline SMH was determined prior to the in vitro acid challenge. SMH was determined again after the in vitro acid challenge, after the in situ remineralization test, and again after the second in vitro acid challenge. The extent of remineralization was calculated as the % recovery in SMH using the equation: % SMHR= \[(D1-R)/(D1-B)\]\*100 Where B = indentation length (μm) of sound enamel at baseline; D1 = indentation length (μm) after first acid challenge; R = indentation length (μm) after in situ remineralization.
Time frame: Baseline to 4 hours
Enamel Fluoride Uptake
The microdrill enamel biopsy technique was used to analyze the fluoride uptake by enamel. Each enamel specimen was mounted on the long axis of a drill attached to a microdrill and drilled to a depth of approximately 100 micrometer (μm) through the entire lesion (four cores per specimen). The enamel powder pooled from four drilling sample was then immediately analyzed for fluoride content using fluoride specific electrode and pH/ion meter. The amount of fluoride-uptake by enamel was calculated based on the amount of fluoride divided by the area of the enamel cores and expressed as microgram per square centimeter (μg/cm\^2).
Time frame: Baseline to 4 hours
Percentage Net Acid Resistance (% NAR)
Changes in the mineral content of the four centrally-located enamel specimens were evaluated using the SMH Test. The SMH was measured using a Wilson 2100 Hardness Tester. The baseline SMH was measured prior to the in vitro acid challenge. SMH was measured again after the in vitro acid challenge, after the in situ remineralization test, and again after the second in vitro acid challenge. The % NAR was calculated using the equation: % NAR= \[(D1-D2)/(D1-B)\]\*100 where B= Indentation length (μm) of sound enamel at baseline; D1= Indentation length (μm) after first acid challenge and D2= Indentation length (μm) after second acid challenge.
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Zinc base A, 1426ppm fluoride as sodium fluoride in a silica gel base
Zinc base B, 1426ppm fluoride as sodium fluoride in a silica gel base
Non-zinc, 0ppm fluoride in a silica gel base
Time frame: Baseline to 4 hours
Percentage Comparative Acid Resistance (% CAR)
Changes in the mineral content of the four centrally-located enamel specimens were evaluated using the SMH Test. The SMH was measured using a Wilson 2100 Hardness Tester. The baseline SMH was measured prior to the in vitro acid challenge. SMH was measured again after the in vitro acid challenge, after the in situ remineralization test, and again after the second in vitro acid challenge. The % CAR was calculated using the equation: % CAR= \[(D2-R)/(D1-B)\]\*100 where B= Indentation length (μm) of sound enamel at baseline; R= Indentation length (μm) of enamel after in situ remineralization; D1= Indentation length (μm) after first acid challenge; D2= Indentation length (μm) after second acid challenge.
Time frame: Baseline to 4 hours