IADR Abstract Archives
Enamel Remineralization Characterized Using Microhardness Measurements and TOF-SIMS With44Ca
Objectives: The use of time-of-flight secondary-ion mass spectrometry (TOF-SIMS) has rarely been applied to study enamel remineralization even though it is ideally suited to the task. The aim here was to investigate four dentifrices regarding remineralization potential by microhardness measurements and to characterize/visualize the remineralized lesions using TOF-SIMS measurements of 40Ca, 44Ca, and F as a new promising evaluation method.
Methods: Artificial caries lesions were made in ground, polished enamel using a Carbopol-based demineralization solution. Following demineralization, a cellulose-based artificial biofilm layer of controlled thickness was placed over the caries lesion and was affixed with a plastic ring. Specimens were cycled in a 1:3 slurry of toothpaste:water in the morning and afternoon and stored in remineralization solution at 37°C. Solutions are based on those previously published [Stookey et al., 2011] with the addition of 0.2% Carbopol 907 to the demineralization solution at pH 4.3. Toothpaste treatments included: a) 0 ppm F; b) 1100 ppm F; c) 5000 ppm F as NaF/silica; and d) 1100 ppm F as stabilized SnF2/silica. Lesion volumes were determined by cross-sectional microhardness according to Stookey et al., 2011. TOF-SIMS measurements were made of the SnF2/silica treatment specimens only.
Results: The lesion volumes (vol%min-µm) following remineralization for the four groups were: a) 3292 ± 1027a; b) 1489 ± 663b; c) 976 ± 733c; and d) 1217 ± 649bc. Treatments with different letters were significantly different: student’s t-test, p<0.05. The use of 44Ca allowed clear disambiguation of the new mineral phase. The distribution of F, while mainly limited to the new mineral, was more widespread throughout the lesion. F and 44Ca penetrated the inter-rod spaces at the interface of sound and demineralized enamel.
Conclusions: The experimental SnF2/silica toothpaste was as effective as the NaF/silica toothpaste for the remineralization of enamel. High-resolution TOF-SIMS has proven here highly useful for studying enamel remineralization.
Methods: Artificial caries lesions were made in ground, polished enamel using a Carbopol-based demineralization solution. Following demineralization, a cellulose-based artificial biofilm layer of controlled thickness was placed over the caries lesion and was affixed with a plastic ring. Specimens were cycled in a 1:3 slurry of toothpaste:water in the morning and afternoon and stored in remineralization solution at 37°C. Solutions are based on those previously published [Stookey et al., 2011] with the addition of 0.2% Carbopol 907 to the demineralization solution at pH 4.3. Toothpaste treatments included: a) 0 ppm F; b) 1100 ppm F; c) 5000 ppm F as NaF/silica; and d) 1100 ppm F as stabilized SnF2/silica. Lesion volumes were determined by cross-sectional microhardness according to Stookey et al., 2011. TOF-SIMS measurements were made of the SnF2/silica treatment specimens only.
Results: The lesion volumes (vol%min-µm) following remineralization for the four groups were: a) 3292 ± 1027a; b) 1489 ± 663b; c) 976 ± 733c; and d) 1217 ± 649bc. Treatments with different letters were significantly different: student’s t-test, p<0.05. The use of 44Ca allowed clear disambiguation of the new mineral phase. The distribution of F, while mainly limited to the new mineral, was more widespread throughout the lesion. F and 44Ca penetrated the inter-rod spaces at the interface of sound and demineralized enamel.
Conclusions: The experimental SnF2/silica toothpaste was as effective as the NaF/silica toothpaste for the remineralization of enamel. High-resolution TOF-SIMS has proven here highly useful for studying enamel remineralization.