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Item Carious lesion remineralizing potential of fluoride- and calcium-containing toothpastes(Elsevier, 2019-05) Lippert, Frank; Gill, Karmjeet K.; Cariology, Operative Dentistry and Dental Public Health, School of DentistryBackground The authors conducted a laboratory study to determine the carious lesion remineralization and fluoridation potential of fluoride (F)- and calcium-containing toothpastes. Methods The authors created early carious lesions in bovine enamel specimens and assigned them to 7 treatment groups on the basis of their surface Vickers microhardness: Clinpro Tooth Crème (Clinpro) (3M ESPE), CTx4 Gel 1100 (CTx4) (Oral Biotech), Enamelon Fluoride Toothpaste (Enamelon) (Premier Dental), MI Paste ONE (MI-One) (GC America), Crest Cavity Protection Toothpaste (Crest) (Procter & Gamble), and 2 F-dose controls (low F, high F). The authors pH cycled the specimens for 10 days by using an established model, determined changes in surface microhardness, calculated percentage of surface microhardness recovery (%SMHr; primary outcome variable), and measured enamel F uptake (EFU). The authors used a 1-way analysis of variance for data analysis. Results Study results showed an F-dose response for both %SMHr (low-F control: mean, 9.8; 95% confidence interval [CI], 5.7 to 13.8); Crest: mean, 26.2; CI, 21.8 to 30.6; high-F control: mean, 33.5; CI, 29.4 to 37.5) and EFU (low-F control: mean, 47; CI, 12 to 83; Crest: mean, 225; CI, 189 to 260; high-F control: mean, 307; CI, 271 to 342; all micrograms of F per cubic centimeter). For %SMHr, Clinpro (mean, 26.5; CI, 22.5 to 30.6) and CTx4 (mean, 27.3; CI, 23.1 to 31.5) were similar to Crest, all being superior to Enamelon (mean, 15.6; CI, 11.6 to 19.7), which was superior to MI-One (mean, 4.3; CI, 0.3 to 8.3). For EFU, there were no differences between Clinpro (mean, 189; CI, 153 to 224), CTx4 (mean, 177; CI, 142 to 213), Enamelon (mean, 196; CI, 161 to 232), and Crest, all being superior to MI-One (mean, 66; CI, 30 to 102). Conclusions This study’s results failed to show superior remineralizing efficacy of any of the toothpastes compared with those of a calcium-free F toothpaste, with 2 of the 4 toothpastes being inferior. Clinical testing will be required to establish conclusive evidence.Item Effect of fluoride and abrasives on artificial enamel caries lesions(2012) Nassar, Hani M., 1979-; Hara, Anderson T.; González-Cabezas, Carlos, 1966-; Lippert, Frank; Fontana, Margherita Ruth, 1966-; Chu, Tien-Min GabrielHypothesis: The interaction between the abrasive level and fluoride concentration of dentifrice slurries modulates the surface loss (SL) and remineralization of incipient enamel caries (IEC). Methods: Three types of IEC were created and six experimental slurries with different combinations of fluoride content and abrasive level were tested. In experiment 1, the three IEC were subjected to brushing (with experimental slurries) and remineralization cycles for 5 days. Fluoride concentrations (0 and 275 ppm as NaF) and abrasive levels (Low and High) were tested. SL was determined by optical profilometry at baseline and after 1, 3, and 5 days. In experiment 2, changes in IEC mineral content (Δ(ΔZ)C) and depth (ΔLC) were investigated at baseline and after the 5-day cycling with transverse microradiography. In experiments 3 and 4, SL of MeC and CMC lesions were further studied, respectively; testing not only fluoride concentration (275 and 1250 ppm as NaF) and abrasivity (low and high) of the slurry, but also the brushing frequency (1x, 2x, and 3x/day). Brushing-remineralization cycles were performed for 7 days. Statistical analyses were performed at 5% significance level. Results: Experiment 1: overall, brushing with the high-abrasive slurry caused more SL than with the low-abrasive. For CMC and MeC lesions, 0 ppm F had more SL than 275 ppm F only after day 3. Fluoride had no effect on the SL of HEC lesions. Experiment 2: fluoride and abrasives did not have a significant effect on IEC. HEC had significantly lower Δ(ΔZ)C than CMC and MeC, with CMC and MeC not differing from each other. Lesion type had no effect on ΔLC. Experiment 3: brushing CMC lesions 3x/day with 1250 ppm F increased SL compared to 1x/day, after 5 and 7 days. Study 4: brushing MeC lesions with high abrasive slurry containing 1250 ppm F increased SL after 5 and 7 days. Conclusions: The IEC tested showed different SL and remineralization behaviors. The fluoride content and abrasive level of the toothpaste showed to be relevant modulating the SL of enamel caries lesions as well as their remineralization behavior.Item Effect of Fluoride, Lesion Baseline Severity and Mineral Distribution on Lesion Progression(Karger, 2012) Lippert, Frank; Butler, A.; Lynch, R. J. M.; Hara, Anderson T.; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryThe present study investigated the effects of fluoride (F) concentration, lesion baseline severity (ΔZbase) and mineral distribution on lesion progression. Artificial caries lesions were created using three protocols [methylcellulose acid gel (MeC), hydroxyethylcellulose acid gel (HEC), carboxymethylcellulose acid solution (CMC)] and with low and high ΔZbase groups by varying demineralization times within protocols. Subsequently, lesions were immersed in a demineralizing solution for 24 h in the presence of 0, 1, 2 or 5 ppm F. Changes in mineral distribution characteristics of caries lesions were studied using transverse microradiography. At baseline, the protocols yielded lesions with three distinctly different mineral distributions. Secondary demineralization revealed differences in F response between and within lesion types. In general, lowΔZ lesions were more responsive to F than highΔZ lesions. LowΔZ MeC lesions showed the greatest range of response among all lesions, whereas highΔZ HEC lesions were almost unaffected by F. Laminations were observed in the presence of F in all but highΔZ HEC and CMC lesions. Changes in mineral distribution effected by F were most pronounced in MeC lesions, with remineralization/mineral redeposition in the original lesion body at the expense of sound enamel beyond the original lesion in a dose-response manner. Both ΔZbase and lesion mineral distribution directly impact the F response and the extent of secondary demineralization of caries lesions. Further studies – in situ and on natural white spot lesions – are required to better mimic in vivo caries under laboratory conditions.Item The effects of lesion baseline characteristics and different Sr:Ca ratios in plaque fluid-like solutions on caries lesion de- and remineralization(Elsevier, 2012-10) Lippert, Frank; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryThis study investigated the effects of lesion baseline characteristics and different strontium (Sr) to calcium (Ca) ratios in plaque fluid-like solutions (PF) on lesion de- and remineralization. Caries lesions were formed in enamel using three protocols: methylcellulose acid gel (MeC) and partially saturated lactic acid solutions containing carboxymethylcellulose (CMC) or not (SOLN). Lesions were exposed to PF with four distinct Sr:Ca molar ratios (0:1/3:1:3), but otherwise identical composition and total Sr+Ca molarity, for seven days. Lesions were characterized using transverse microradiography (TMR) at baseline and post-treatment. At baseline, MeC and CMC had similar integrated mineral loss values, whereas SOLN lesions were more demineralized. All lesions showed significant differences in their mineral distributions, with CMC and SOLN having lower R values (integrated mineral loss to lesion depth ratio) than MeC. Post-PF exposure, no interaction was found between lesion type and Sr:Ca ratio. Within lesion type, MeC demineralized, whereas CMC and SOLN exhibited some remineralization, with the differences between MeC and the other lesion types being of statistical significance. Within Sr:Ca ratio, the 1:3 ratio exhibited some remineralization whereas other groups tended to demineralize. Only the difference between groups SrCa1/3 and SrCa0 was of statistical significance. In summary, both lesion baseline characteristics and Sr:Ca ratio were shown to effect lesion de- and remineralization. Under the conditions of the study, high-R lesions are more prone to demineralize under PF-like conditions than low-R lesions. In addition, partial Sr substitution for Ca in PF was shown to enhance lesion remineralization.