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Item Dose-Response Effects of Zinc and Fluoride on Caries Lesion Remineralization(Karger, 2012-02) Lippert, Frank; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryThe present mechanistic in vitro study aimed to investigate dose-response effects of zinc and fluoride on caries lesion remineralization and subsequent protection from demineralization. Artificial caries lesions were created using a methylcellulose acid gel system. Lesions were remineralized for 2 weeks using citrate-containing artificial saliva which was supplemented with zinc (0–153 µmol/l) and fluoride (1.1 or 52.6 µmol/l) in a 7 × 2 factorial design. Lesions were also remineralized in the absence of zinc and citrate, but in the presence of fluoride. After remineralization, all lesions were demineralized for 1 day under identical conditions. Changes in mineral distribution characteristics of caries lesions after remineralization and secondary demineralization were studied using transverse microradiography. At 1.1 µmol/l fluoride, zinc exhibited detrimental effects on remineralization in a dose-response manner and mainly by preventing remineralization near the lesion surface. At 52.6 µmol/l fluoride, zinc retarded remineralization only at the highest concentration tested. Zinc enhanced overall remineralization at 3.8–15.3 µmol/l. At 76.5 and less so at 153 µmol/l, zinc showed extensive remineralization of deeper parts within the lesions at the expense of remineralization near the surface. Citrate did not interfere with remineralization at 1.1 µmol/l fluoride, but enhanced remineralization at 52.6 µmol/l fluoride. Lesions exhibiting preferential remineralization in deeper parts showed higher mineral loss after secondary demineralization, suggesting the formation of more soluble mineral phases during remineralization. In summary, zinc and fluoride showed synergistic effects in enhancing lesion remineralization, however only at elevated fluoride concentrations.Item Effect of phytate and zinc ions on fluoride toothpaste efficacy using an in situ caries model(Elsevier, 2018) Parkinson, Charles; Burnett, Gary R.; Creeth, Jon; Lynch, Richard; Budhawant, Chandrashekhar; Lippert, Frank; Hara, Anderson T.; Zero, Domenick T.; Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjectives To compare and explore the dose-response of phytate-containing 1150 ppm fluoride toothpastes on model caries lesions and to determine the impact of zinc ions. Methods This was a single-centre, randomised, blinded (examiner/laboratory analyst), six-treatment, four-period crossover, in situ study in adults with a removable bilateral maxillary partial denture. Study treatments were toothpastes containing: 0.425% phytate/F; 0.85% phytate/F; 0.85% phytate/Zn/F; F-only; Zn/F and a 0% F placebo. Where present, F was 1150 ppm as NaF; Zn was 0.3% as ZnCl2. Human enamel specimens containing early-stage, surface-softened (A-lesions) or more advanced, subsurface (B-lesions) caries lesions were placed into the buccal flanges of participants’ modified partial denture (one of each lesion type per side). A-lesions were removed after 14 days of twice-daily treatment use; B-lesions were removed after a further 14 days. A-lesions were analysed for surface microhardness recovery. Both lesion types were analysed by transverse microradiography and for enamel fluoride uptake, with B-lesions additionally analysed by quantitative light-induced fluorescence. Comparison was carried out using an analysis of covariance model. Results Statistically significant differences between 1150 ppm F and the placebo toothpastes (p < 0.05) were shown for all measures, validating the model. No differences between fluoride toothpastes were observed for any measure with little evidence of a dose-response for phytate. Study treatments were generally well-tolerated. Conclusions Results suggest phytate has little impact on fluoride’s ability to promote early-stage lesion remineralisation or prevent more advanced lesion demineralisation in this in situ caries model. Similarly, results suggest zinc ions do not impair fluoride efficacy.Item Effect of silver diamine fluoride on the prevention of erosive tooth wear in vitro(Elsevier, 2020) Ainoosah, Sultan E.; Levon, John; Eckert, George J.; Hara, Anderson T.; Lippert, Frank; Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjectives To investigate the ability of silver diamine fluoride (SDF) to prevent erosive tooth wear in enamel and dentin. Methods SDF (38 %) was compared to deionized water (DIW, negative control), potassium fluoride (KF, fluoride control), silver nitrate (AgNO3, silver control), and fluoride varnish (FV, clinical reference) using erosion and erosion-abrasion cycling models. Bovine enamel and dentin slabs were embedded in resin blocks. Two resin blocks were glued to form study blocks (n = 8, per treatment), one for erosion and the other for the erosion-abrasion model. The blocks were treated once and then subjected to a five-day cycling model, with five daily citric acid erosive challenges (0.3 % citric acid/pH 2.6). Abrasion was performed using a toothbrushing machine with a medium-abrasive silica as abrasive (erosion-abrasion model only). Artificial saliva was used to remineralize the specimens after erosion/abrasion and as storage media between cycles. Surface loss (SL) was determined by non-contact profilometry. Data were analyzed using ANOVA (α = 0.05). Results Both eroded-abraded enamel and dentin specimens exhibited significantly more SL in all treatment groups than the only eroded ones (p < 0.001). For dentin, both AgNO3 and DIW groups had significantly more SL than SDF, KF, and FV groups (p < 0.001), for both models. For enamel, specimens had more SL in both AgNO3 and DIW groups compared to SDF, KF, and FV groups, in the erosion model. When enamel specimens were subjected to erosion-abrasion, FV resulted in the least SL (p < 0.001). Conclusion SDF was effective in reducing dental erosion on both substrates, but dental erosion-abrasion only on dentin. Clinical significance SDF may become a viable intervention for ETW prevention in dentin (e.g. exposed roots) once its efficacy has been confirmed under clinical conditions.Item The effect of theobromine on the in vitro de- and remineralization of enamel carious lesions(Elsevier, 2020) Thorn, Anna K.; Lin, Wei-Shao; Levon, John A.; Morton, Dean; Eckert, George J.; Lippert, Frank; Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjectives This in vitro study investigated the effect of theobromine on the de- and remineralization of enamel carious lesions under plaque fluid-like conditions. Methods Early carious lesions were created in 272 bovine enamel specimens and assigned to sixteen groups (n = 17) based on Knoop surface microhardness (SMH). Lesions were demineralized again under plaque fluid-like conditions in the presence of fluoride (0.2 or 1 ppm) and theobromine (0; 10; 100 or 200 ppm) at different pH values (5.5 or 7.0) in a factorial design. SMH was determined again and percent SMH recovery (%SMHr) calculated. Three-way ANOVA was used for the fixed effects of fluoride, theobromine and pH levels to compare the differences between each level. Results The three-way interaction was not significant (p = 0.712). The two-way interaction between fluoride and pH was significant (p = 0.030), whereas those between fluoride and theobromine as well as that for pH and theobromine were not (p = 0.478 and p = 0.998, respectively). Theobromine did not affect %SMHr at any of the tested concentrations. There were trends for the higher fluoride concentration and the higher pH resulting in more rehardening with the lesions exposed to 0.2 ppm fluoride at pH 5.5 displaying significantly less rehardening than those exposed to 0.2 ppm fluoride at pH of 7.0 and lesions exposed to 1 ppm fluoride at pH of 5.5. Conclusion Theobromine, when continuously present in a plaque fluid-like medium at various concentrations and at different pH values, does not affect de- or remineralization of enamel carious lesions under the presently studied conditions.Item The Effects of Fluoride, Strontium, Theobromine and their Combinations on Caries Lesion Rehardening and Fluoridation(Elsevier, 2017-08) Lippert, Frank; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjective The aim was to investigate the effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation (EFU) under pH cycling conditions. Design Human enamel specimens were demineralized at 37 °C for 24 h using a pH 5.0 solution containing 50 mM lactic acid and 0.2% Carbopol 907 which was 50% saturated with respect to hydroxyapatite. Lesions were assigned to nine treatment groups (n = 16) based on Knoop surface microhardness indentation length. Treatment aqueous solutions were: placebo, 11.9 mM sodium fluoride (F), 23.8 mM sodium fluoride (2 × F), 1.1 mM strontium chloride hexahydrate (Sr), 1.1 mM F theobromine, Sr + theobromine, F + Sr, F + theobromine, F + Sr + theobromine. Lesions were pH cycled for 5d (daily protocol: 3 × 1min-treatment; 2 × 60min-demineralization; 4 × 60 min & overnight-artificial saliva). Knoop indentation length was measured again and%surface microhardness recovery (%SMHr) calculated. EFU was determined using the acid-etch technique. Data were analysed using ANOVA. Results Model showed fluoride dose-response for both variables (2 × F > F > placebo). For%SMHr, F + Sr+/−theobromine resulted in more rehardening than F, however less than 2 × F. F + theobromine was similar to F. For EFU, F + Sr was inferior to F, F + theobromine and F + Sr + theobromine which were similar and inferior to 2 × F. In absence of fluoride, Sr, theobromine or Sr + theobromine were virtually indistinguishable from placebo and inferior to F. Conclusions It can be concluded that a) strontium aids rehardening but not EFU and only in presence of fluoride; b) theobromine does not appear to offer any anti-caries benefits in this model; c) there are no synergistic effects between strontium and theobromine in the presence or absence of fluoride.Item Exploratory randomized clinical trial of an experimental gel-to-foam fluoride dentifrice formulation using an in situ caries model(2015) Barlow, Ashley; Butler, Andrew; Mason, Stephen; Zero, Domenick; Department of Cariology, Operative Dentistry, and Dental Public Health, IU School of DentistryOBJECTIVE: To evaluate the in situ caries performance and safety of two experimental fluoride dentifrice formulations (1450 ppm fluoride) with and without 2% isopentane as an excipient, in comparison to a positive control, currently marketed dentifrice (1450 ppm fluoride) and a negative control dentifrice (0 ppm fluoride). METHODS: This was a single-center, examiner-blind, randomized, controlled, four-treatment cross-over study. During each treatment period, the subject wore a modified mandibular partial denture fitted with two gauze-covered, partially demineralized human enamel specimens, and brushed at home for one timed minute, twice daily, for two weeks. At the end of each treatment period, the enamel specimens were removed from the dentures for analysis. During the week between treatment periods, subjects returned to their usual dental hygiene practices for four to five days, received a dental prophylaxis, and used a study-designated non-fluoride dentifrice for two to three days before starting the next treatment. Treatment effect on enamel specimen remineralization was assessed by surface microhardness (SMH). Enamel fluoride uptake was assessed using microdrill enamel biopsy. RESULTS: All fluoride-containing dentifrices demonstrated significant, superior SMH recovery and levels of fluoride uptake compared to the negative control dentifrice. No significant differences were observed for either efficacy variable between the experimental dentifrice formulations and the positive control dentifrice. No significant difference was observed between the 2% isopentane dentifrice and the 0% isopentane dentifrice for SMH recovery. CONCLUSION: The addition of 2% isopentane did not positively or negatively affect fluoride efficacy in this model.Item Imaging of demineralized enamel in intact tooth by epidetected stimulated Raman scattering microscopy(SPIE, 2018) Ando, Masatoshi; Liao, Chien-Sheng; Eckert, George J.; Cheng, Ji-Xin; Cariology, Operative Dentistry and Dental Public Health, School of DentistryStimulated Raman scattering microscopy (SRS) was deployed to quantify enamel demineralization in intact teeth. The surfaces of 15 bovine-enamel blocks were divided into four equal-areas, and chemically demineralized for 0, 8, 16, or 24 h, respectively. SRS images (spectral coverage from ∼850 to 1150 cm − 1) were obtained at 10-μm increments up to 90 μm from the surface to the dentin–enamel junction. SRS intensities of phosphate (peak: 959 cm − 1), carbonate (1070 cm − 1), and water (3250 cm − 1) were measured. The phosphate peak height was divided by the carbonate peak height to calculate the SRS-P/C-ratio, which was normalized relative to 90 μm (SRS-P/C-ratio-normalized). The water intensity against depth decay curve was fitted with exponential decay. A decay constant (SRS-water-content) was obtained. Knoop-hardness values were obtained before (SMHS) and after demineralization (SMHD). Surface microhardness-change (SMH-change) [ ( SMHD − SMHS ) / SMHS] was calculated. Depth and integrated mineral loss (ΔZ) were determined by transverse microradiography. Comparisons were made using repeated-measures of analysis of variance. For SRS-P/C-ratio-normalized, at 0-μm (surface), sound (0-h demineralization) was significantly higher than 8-h demineralization and 24-h demineralization; 16-h demineralization was significantly higher than 24-h demineralization. For SRS-water-content, 24-h demineralization was significantly higher than all other demineralization-groups; 8-h demineralization and 16-h demineralization were significantly higher than 0-h demineralization. SRS-water-content presented moderate-to-strong correlation with SMH-change and weak-to-moderate correlation with depth. These results collectively demonstrate the potential of using SRS microscopy for in-situ chemical analysis of dental caries.Item In situ evaluation of fluoride-, stannous- and polyphosphate-containing solutions against enamel erosion(Elsevier, 2017) João-Souza, Samira Helena; Bezerra, Sávio José C.; de Freitas, Patricia Moreira; de Lima, Nelson B.; Corrêa Aranha, Ana Cecilia; Hara, Anderson T.; Scaramucci, Taís; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjective To evaluate the anti-erosive effect of solutions containing sodium fluoride (F: 225 ppm of fluoride), sodium fluoride + stannous chloride (F + Sn: 225 ppm of fluoride + 800 ppm of stannous), sodium fluoride + stannous chloride + sodium linear polyphosphate (F + Sn + LPP: 225 ppm of fluoride + 800 ppm of stannous + 2% of sodium linear polyphosphate), and deionized water (C: control), using a four-phase, single-blind, crossover in situ clinical trial. Methods In each phase, 12 volunteers wore appliances containing 4 enamel specimens, which were submitted to a 5-day erosion-remineralization phase that consisted of 2 h of salivary pellicle formation with the appliance in situ, followed by 2 min extra-oral immersion in 1% citric acid (pH 2.4), 6x/day, with 90 min of exposure to saliva in situ between the challenges. Treatment with the test solutions was performed extra-orally for 2 min, 2x/day. At the end of the experiment, surface loss (SL, in μm) was evaluated by optical profilometry. Data were analyzed using ANOVA and Tukey tests (α = 0.05). The surface of additional specimens was evaluated by x-ray diffraction after treatments (n = 3). Results C (mean SL ± standard-deviation: 5.97 ± 1.70) and F (5.36 ± 1.59) showed the highest SL, with no significant difference between them (p > 0.05). F + Sn (2.68 ± 1.62) and F + Sn + LPP (2.10 ± 0.95) did not differ from each other (p > 0.05), but presented lower SL than the other groups (P < 0.05). Apatite and stannous deposits on specimen surfaces were identified in the x-ray analysis for F + Sn and F + Sn + LPP. Conclusions Sodium fluoride solution exhibited no significant anti-erosive effect. The combination between sodium fluoride and stannous chloride reduced enamel erosion, irrespective of the presence of linear sodium polyphosphate. Clinical significance Under highly erosive conditions, sodium fluoride rinse may not be a suitable alternative to prevent enamel erosion. A rinse containing sodium fluoride and stannous chloride was shown to be a better treatment option, which was not further improved by addition of the sodium linear polyphosphate.Item The influence of hardness and chemical composition on enamel demineralization and subsequent remineralization(Elsevier, 2018-08) Alkattan, Rana; Lippert, Frank; Tang, Qing; Eckert, George J.; Ando, Masatoshi; Cariology, Operative Dentistry and Dental Public Health, School of DentistryObjectives The objectives were to investigate the hardness and chemical composition of sound, demineralized and pH-cycled bovine enamel and determine their influence on demineralization and remineralization behavior. Methods Ninety-four, 5 × 5 × 2-mm bovine enamel specimens were demineralized using three different times [(24 h (n = 33), 48 h (n = 30), 96 h (n = 31)]. The specimens were then pH-cycled using either 367 ppm F sodium fluoride or deionized water. Knoop hardness (HK) and energy-dispersive X-ray spectroscopy (measured elements: Ca, P, F, C, Mg, N) were performed at three stages (sound, after demineralization, after pH-cycling) and transverse microradiography was performed after demineralization and pH-cycling. Comparisons were determined by ANOVA. Results Results showed that HK, integrated mineral loss and lesion depth were significantly different between stages, demineralization times and treatments. The weight% of F at the surface was significantly affected by treatment, irrespective of demineralization time, while the Ca:P ratio of the enamel remained stable even after de- and remineralization protocols. The F in fluoride groups and the artificial saliva in non-fluoride groups were both able to induce enamel remineralization, indicating the protective effect of salivary pellicle against demineralization even in the absence of fluoride. Conclusions Harder specimens and those with greater surface F weight% were less susceptible to demineralization and were more likely to remineralize. However, the amount of surface Ca and P did not influence de- or remineralization behavior.Item Mechanistic Observations on the Role of the Stannous Ion in Caries Lesion De- and Remineralization(Karger, 2016-09) Lippert, Frank; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryTwo mechanistic, laboratory, factorial design studies were conducted to investigate the effect of the stannous ion (Sn2+) in the absence or presence of fluoride on caries lesion de- and remineralization. Study I was concerned with determining changes in mineral distribution of subsurface lesions, whereas study II investigated changes in surface hardness of surface-softened lesions as a function of pH. Study I showed that Sn2+ modulates the effects of fluoride by preventing lamination. Study II revealed that the effect of Sn2+ on rehardening is pH dependent. Neither study demonstrated synergy between Sn2+ and fluoride, yet interactions were observed. Sn2+ does interfere with remineralization to some extent although it provided acid resistance. The role of Sn2+ in the caries process is complex.