Protective effect of experimental mouthrinses containing NaF and TiF4 on dentin erosive loss in vitro

Objective

This in vitro study assessed the anti-erosive effect of experimental mouthrinses containing TiF₄ and NaF on dentin erosive loss.

Material and Methods

Bovine dentin specimens were randomly allocated into the groups (n=15): 1) SnCl₂/NaF/AmF (Erosion Protection^®/GABA, pH 4.5, positive control); 2) experimental solution with 0.0815% TiF₄ (pH 2.5); 3) 0.105% NaF (pH 4.5); 4) 0.042% NaF+0.049% TiF₄ (pH 4.4); 5) 0.063% NaF+0.036% TiF₄ (pH 4.5); 6) no treatment (negative control). Each specimen was cyclically demineralized (Sprite Zero, pH 2.6, 4x90 s/day) and exposed to artificial saliva between the erosive challenges for 7 days. The treatment with the fluoride solutions was done 2x60 s/day, immediately after the first and the last erosive challenges of the day. Dentin erosive loss was measured by profilometry (μm). The data were analyzed using Kruskal Wallis/Dunn tests (p<0.05).

Results

Mouthrinses containing TiF₄ or Sn/F were able to show some protective effect against dentin erosive loss compared to negative control. The best anti-erosive effect was found for experimental solution containing 0.0815% TiF₄ (100% reduction in dentin loss), followed by 0.042% NaF+0.049% TiF⁴ (58.3%), SnCl₂/NaF/AmF (52%) and 0.063% NaF+0.036% TiF₄ (40%). NaF solution (13.3%) did not significantly differ from control.

Conclusion

The daily application of experimental mouthrinse containing TiF₄ and NaF has the ability to reduce dentin erosion, as well as Erosion Protection^® and TiF₄ alone.     

Efficacy of the stannous ion and a biopolymer in toothpastes on enamel erosion/abrasion

Objectives

Sn²⁺ has promising erosion-inhibiting properties in solutions, but little is known about respective effects in toothpastes. In addition, biopolymers might have protecting potential. Aim of this study was to investigate the effects of Sn²⁺ in toothpastes and of a biopolymer (chitosan) added to a Sn²⁺ formulation on erosion/abrasion.

Methods

Enamel samples were subjected to cyclic erosion procedures (10 days; 0.50% citric acid, pH 2.5; 6× 2 min/day), and brushing (2× 15 s/day, load 200 g) during immersion in slurries (2 min). The toothpastes were NaF formulations (NaF/1, NaF/2, NaF/3) and Sn²⁺ formulations (NaF/SnCl₂, AmF/SnF₂, AmF/NaF/SnCl₂) and AmF/NaF/SnCl₂ + 0.5% chitosan.Declared concentrations of active ingredients in toothpastes were 1400–1450 μg/g F⁻ and 3280–3500 μg/g Sn²⁺. Negative controls were erosion only and placebo, positive control was a SnF₂ gel. Tissue loss was quantified profilometrically, Sn on enamel surfaces was measured by energy dispersive X-ray spectroscopy.

Results

Loss values (μm) for erosion only and placebo were 14.4 ± 4.5 and 20.2 ± 3.8, respectively, and 4.6 ± 1.9 for the positive control (p ≤ 0.001 each compared to erosion only). The other loss values were: NaF/1 16.5 ± 3.0, NaF/2 14.0 ± 2.7, NaF/3 12.6 ± 3.9, NaF/SnCl₂ 14.7 ± 5.1, AmF/SnF₂ 13.5 ± 4.8, AmF/NaF/SnCl₂ 12.4 ± 4.2, AmF/NaF/SnCl₂ + chitosan 6.6 ± 3.5 (except NaF/1 all p ≤ 0.01 compared to placebo). AmF/NaF/SnCl₂/chitosan was more effective than all other toothpastes (p ≤ 0.01 each). Sn on the enamel surface ranged between 1.3 ± 0.3 and 2.8 ± 0.04 wt.% with no obvious relationship with efficacy.

Conclusions

The NaF and Sn²⁺ toothpastes without chitosan exhibited similar anti-erosion and abrasion-prevention effects. The experimental Sn²⁺ formulation with chitosan revealed promising results similar to those of the positive control.

Clinical significance

NaF toothpastes offer a degree of protection against erosion/abrasion, which is likely sufficient for most subjects with average acid exposures. For patients with initial erosive lesions, however, more effective toothpaste is desirable. The combination of Sn²⁺ and a biopolymer appears promising in this context.     

Prevention of dentine erosion by brushing with anti-erosive toothpastes

Objective

This in vitro study aimed to investigate the preventive effect of brushing with anti-erosive toothpastes compared to a conventional fluoride toothpaste on dentine erosion.

Materials and methods

Bovine dentine specimens (n = 12 per subgroup) were eroded in an artificial mouth (6 days, 6 × 30 s/day) using either citric acid (pH:2.5) or a hydrochloric acid/pepsin solution (pH:1.6), simulating extrinsic or intrinsic erosive conditions, respectively. In between, the specimens were rinsed with artificial saliva. Twice daily, the specimens were brushed for 15 s in an automatic brushing machine at 2.5 N with a conventional fluoride toothpaste slurry (elmex, AmF) or toothpaste slurries with anti-erosive formulations: Apacare (NaF/1% nHAP), Biorepair (ZnCO₃-HAP), Chitodent (Chitosan), elmex Erosionsschutz (NaF/AmF/SnCl₂/Chitosan), mirasensitive hap (NaF/30% HAP), Sensodyne Proschmelz (NaF/KNO₃). Unbrushed specimens served as control. Dentine loss was measured profilometrically and statistically analysed using two-way and one-way ANOVA followed by Scheffe‘s post hoc tests. RDA-values of all toothpastes were determined, and linear mixed models were applied to analyse the influence of toothpaste abrasivity on dentine wear (p < 0.05).

Results

Dentine erosion of unbrushed specimens amounted to 5.1 ± 1.0 μm (extrinsic conditions) and 12.9 ± 1.4 μm (intrinsic conditions). All toothpastes significantly reduced dentine erosion by 24–67% (extrinsic conditions) and 21–40% (intrinsic conditions). Biorepair was least effective, while all other toothpastes were not significantly different from each other. Linear mixed models did not show a significant effect of the RDA-value of the respective toothpaste on dentine loss.

Conclusion

Toothpastes with anti-erosive formulations reduced dentine erosion, especially under simulated extrinsic erosive conditions, but were not superior to a conventional fluoride toothpaste.     

Effect of a single application of TiF4 and NaF varnishes and solutions on dentin erosion in vitro

Objectives

This in vitro study aimed to analyse the effect of a single application of TiF₄ and NaF varnishes and solutions to protect against dentin erosion.

Methods

Bovine root dentin samples were pre-treated with NaF-Duraphat varnish (2.26%F, pH 4.5), NaF/CaF₂-Duofluorid varnish (5.63%F, pH 8.0), NaF-experimental varnish (2.45%F, pH 4.5), TiF₄-experimental varnish (2.45%F, pH 1.2), NaF solution (2.26%F, pH 4.5), TiF₄ solution (2.45%F, pH 1.2) and placebo varnish (pH 5.0, no-F varnish control). Controls remained untreated. Ten samples in each group were then subjected to an erosive demineralisation (Sprite Zero, 4× 90 s/day) and remineralisation (artificial saliva, between the erosive cycles) cycling for 5 days. Dentin loss was measured profilometrically after pre-treatment and after 1, 3 and 5 days of de-remineralisation cycling. The data were statistically analysed by two-way ANOVA and Bonferroni's post hoc test (p < 0.05).

Results

After pre-treatment, TiF₄ solution significantly induced surface loss (1.08 ± 0.53 μm). Only Duraphat reduced the dentin loss overtime, but it did not significantly differ from placebo varnish (at 3rd and 5th days) and TiF₄ varnish (at 3rd day).

Conclusions

Duraphat varnish seems to be the best option to partially reduce dentin erosion. However, the maintenance of the effects of this treatment after successive erosive challenges is limited.     

Randomised in situ trial on the effect of milk and CPP-ACP on dental erosion

Objectives

This randomised in situ study aimed to analyse the effect of milk (with or without 5 ppm F) and CPP-ACP pastes (with or without 900 ppm F) on dental erosion.

Methods

The study was a seven phase (5 days each) crossover design involving 15 participants wearing intraoral appliances with enamel and dentine specimens. Specimens were extraorally eroded (erosive soft drink, 6 × 90 s/day) and brushed (2 × 30 s/day, 2 N) using a non-fluoridated toothpaste (negative control). The test products were milk, milk + 5 ppm F (twice daily, each 100 ml/2 min), CPP-ACP paste, CPP-ACP paste + 900 ppm F (3 min/day) or a SnCl₂/AmF/NaF mouthrinse (positive control, 30 s/day), which were applied immediately after erosion with the appliances in the oral cavity. In an additional group, a fluoridated toothpaste was used without any additional test product. Tissue loss was determined profilometrically after 5 days and statistically analysed by linear mixed models methodologies (p < 0.05).

Results

Compared with the negative control (non-fluoridated toothpaste only, enamel: 2.2 ± 1.3 μm; dentine: 3.8 ± 2.2 μm), enamel and dentine loss was significantly reduced by the use of fluoridated toothpaste (enamel: 1.1 ± 1.0 μm; dentine: 2.4 ± 1.7 μm) and the SnCl₂/AmF/NaF mouthrinse (1.5 ± 1.5 μm; dentine: 1.8 ± 1.9 μm).

Conclusions

Milk and CPP-ACP were not effective in reducing enamel and dentine loss significantly, independently of the presence of fluoride.

Clinical significance

Enamel and dentine erosion were significantly reduced by the use of a fluoridated toothpaste or a SnCl₂/AmF/NaF mouthrinse, but not by milk or CPP-ACP under the conditions of the present study.

Clinical trials registration

NCT01566357.     

Does tin pre-treatment enhance the bond strength of adhesive systems to enamel?

Objectives

The study investigated the modification of composite-to-enamel bond strength by pre-treatment of enamel with a concentrated, acidic SnCl₂-solution.

Methods

Six groups of flat human enamel specimens (n = 44 per group) were treated as follows: OB-H: H₃PO₄ etching, Optibond FL application (primer + adhesive; manufacturer's instructions); OB-S: SnCl₂ pre-treatment, Optibond FL application (primer + adhesive); OB-HS: H₃PO₄ etching + SnCl₂ pre-treatment, Optibond FL application (primer + adhesive); CF-N: Clearfil SE application (primer + bond; manufacturer's instructions); CF-H: H₃PO₄ etching, Clearfil SE application (primer + bond); CF-S: SnCl₂ pre-treatment, Clearfil SE application (primer + bond). Enamel specimens were then built up with resin composite (Clearfil Majesty Esthetic) and stored (100% humidity, 37 °C, 1 week). μTBS-measurement and failure mode analysis of one-half of the specimens were performed immediately after storage, while the other half was analysed after a thermocycling procedure (8500 cycles; 5 °C and 55 °C; dwell time 30 s). Additional specimens were prepared for SEM- and EDX-analysis.

Results

Highest values were measured for OB-H before and after thermocycling, lowest values for CF-N. Compared to OB-H treatment, OB-S treatment reduced μTBS before/after thermocycling by 23%/28% and OB-HS treatment by 8%/24% (except for OB-SH before (n.s.), all p ≤ 0.001 compared to OB-H). In the Clearfil SE treated groups pre-treatment increased μTBS significantly compared to CF-N (before/after: CF-H: +46%/+70%; CF-S: +51%/42%; all p ≤ 0.001).

Conclusion

Pre-treatment with H₃PO₄ or SnCl₂ markedly increased the μTBS of Clearfil SE to enamel. However, thermocycling partly reduced the gain in μTBS obtained by SnCl₂ pre-treatment.

Clinical significance

The application of an acidic and highly concentrated SnCl₂ solution is a good option to increase the μTBS between enamel and a resin composite mediated by an adhesive system containing the multifunctional monomer MDP.     

The effect of increasing sodium fluoride concentrations on erosion and attrition of enamel and dentine in vitro

Objectives

To investigate the effect of an aqueous sodium fluoride solution of increasing concentration on erosion and attrition of enamel and dentine in vitro.

Methods

Enamel and dentine sections from caries-free human third molars were polished flat and taped (exposing a 3 mm × 3 mm area) before being randomly allocated to 1 of 5 groups per substrate (n = 10/gp): G1 (distilled water control); G2 (225 ppm NaF); G3 (1450 ppm NaF); G4 (5000 ppm NaF); G5 (19,000 ppm NaF). All specimens were subjected to 5, 10 and 15 cycles of experimental wear [1 cycle = artificial saliva (2 h, pH 7.0) + erosion (0.3% citric acid, pH 3.2, 5 min) + fluoride/control (5 min) + attrition (60 linear strokes in artificial saliva from enamel antagonists loaded to 300 g)]. Following tape removal, step height (SH) in μm was measured using optical profilometry.

Results

When the number of cycles increased the amount of tooth surface loss increased significantly in enamel and dentine after attrition and erosion and for dentine after attrition. Attrition and erosion resulted in greater surface loss than attrition alone after 15 cycles of experimental wear of enamel. 5000 ppm and 19,000 ppm sodium fluoride solutions had a protective effect on erosive and attritional enamel tooth wear in vitro, however no other groups showed significant differences.

Conclusions

The more intensive the fluoride regime the more protection was afforded to enamel from attrition and erosion. However, in this study no such protective effect was demonstrated for dentine.     

TiF4 and NaF at pH 1.2 but not at pH 3.5 are able to reduce dentin erosion

Objective

This study aimed to analyse and compare the protective effect of buffered (pH 3.5) and native (pH 1.2) TiF₄ in comparison to NaF solutions of same pH on dentin erosion.

Design

Bovine samples were pretreated with 1.50% TiF₄ or 2.02% NaF (both 0.48 M F) solutions, each with a pH of 1.2 and 3.5. The control group received no fluoride pretreatment. Ten samples in each group were eroded with HCl (pH 2.6) for 10 × 60 s. Erosion was analysed by determination of calcium release into the acid. Additionally, the surface and the elemental surface composition were examined by scanning electron microscopy (two samples in each group) and X-ray energy-dispersive spectroscopy in fluoridated but not eroded samples (six samples in each group). Cumulative calcium release (nmol/mm²) was statistically analysed by repeated measures ANOVA and one-way ANOVA at t = 10 min.

Results

TiF₄ and NaF at pH 1.2 decreased calcium release significantly, while TiF₄ and NaF at pH 3.5 were not effective. Samples treated with TiF₄ at pH 1.2 showed a significant increase of Ti, while NaF pretreatment increased F concentration significantly. TiF₄ at pH 1.2 led to the formation of globular precipitates occluding dentinal tubules, which could not be observed on samples treated with TiF₄ at pH 3.5. NaF at pH 1.2 but not at pH 3.5 induced the formation of surface precipitates covering dentinal tubules.

Conclusion

Dentin erosion can be significantly reduced by TiF₄ and NaF at pH 1.2, but not at pH 3.5.     

Effect of fluoride varnish supplemented with sodium trimetaphosphate on enamel erosion and abrasion: An in situ/ex vivo study

Objective

To evaluate the effect of fluoride (F) varnishes supplemented or not with sodium trimetaphosphate (TMP) on enamel erosive wear followed or not by abrasion in situ.

Methods

Ten volunteers were selected and randomly divided into four groups, according to the varnishes tested: placebo (no F or TMP), 5% NaF (positive control), 2.5% NaF and 2.5% NaF/5% TMP. Enamel blocks (n = 4) were mounted in palatal devices and received an application of each test varnish, following a double-blind, crossover protocol. After 6 h, varnishes were completely removed and the blocks were subjected to erosive challenges by ex vivo immersion in citric acid (5 min, 4×/dia, 5 days). Following, half of the blocks were subjected to abrasion by brushing with a placebo dentifrice slurry for 15 s. Enamel wear (μm), surface hardness (SH_f) and cross-sectional hardness (ΔKHN) were assessed after each experimental period. Results were analyzed by ANOVA, Student–Newman–Keuls's test and Pearson correlation coefficient (p < 0.05).

Results

The fluoride varnish supplemented with TMP promoted significantly lower wear and ΔKHN when compared to the other groups after erosive challenges, followed or not by abrasion (p < 0.05). As for (SH_f) the fluoride varnish supplemented with TMP promoted similar results to the 5% NaF product, being significantly higher than the remaining groups after erosive and erosive + abrasive challenges (p < 0.05).

Conclusion

TMP significantly enhanced the effects of F on enamel wear after erosive challenges, followed or not by abrasion.     

Efficacy of TiF4 and NaF varnish and solution: a randomized in situ study on enamel erosive–abrasive wear

Objectives

This in situ/ex vivo study analysed the anti-erosive/abrasive effect of TiF₄ and NaF varnish and solution on enamel wear.

Materials and methods

Twelve subjects took part in this study which was performed in three periods (phases) with the duration of 5 days each. Each two human enamel specimens per subject were pretreated with experimental NaF varnish or solution (phase A), experimental-TiF₄ varnish or solution (phase B) and placebo varnish or untreated control (phase C). The specimens were worn in palatal appliances; one enamel specimen, from each treatment, was subjected to erosion (ERO; cola soft drink, 4?×?90 s/day), and the other specimen was subjected to erosion plus abrasion (ERO + ABR; tooth brushing, 2?×?10 s/day). The tooth wear was quantified by a contact profilometer (micrometre) and analysed using two-way repeated measures ANOVA and Bonferroni’s test (n?=?12 subjects, p?<?0.05).

Results

All fluoride varnishes and solutions reduced the enamel wear (around 25 %) significantly compared to the control and placebo varnish. There were no significant differences among the fluoride formulations and between the conditions ERO and ERO + ABR.

Conclusions

Therefore, it can be concluded that TiF₄ has the same protective potential as NaF formulations to reduce human enamel wear under this experimental in situ model.

Clinical significance

In vitro studies have indicated a better anti-erosive/abrasive effect of TiF₄ compared to NaF varnish. The present in situ study does not support the previous findings. Therefore, any of the tested professional fluoride varnishes in principle could be able to partially reduce enamel wear.     

Combined effect of amoxicillin and sodium fluoride on the structure of developing mouse enamel in vitro

Objective

Excess fluoride intake during tooth development is known to cause dental fluorosis. It has also been suggested that amoxicillin use in early childhood is associated with enamel hypomineralization. The aim was to investigate separate and combined effects of sodium fluoride (NaF) and amoxicillin on enamel formation in vitro.

Design

Mandibular molar tooth germs of E18 mouse embryos were cultured for 10 days in a medium containing NaF (10, 12 or 15 μM) and/or amoxicillin (0.5, 1, 2 or 3.6 mg/mL) or sodium clavulanate (0.07 mg/mL) alone or in combination with 0.5 mg/mL of amoxicillin. Morphological changes were studied from the whole tooth photographs and histological tissue sections with light microscope.

Results

Only with the highest concentrations of NaF or amoxicillin alone the extent of enamel in the first molars measured as the vertical enamel height/crown height ratio was reduced (p < 0.01, p < 0.001, respectively). At lower concentrations, combination of NaF (12 μM) and amoxicillin (2 mg/mL) significantly reduced enamel extent compared with the controls (p < 0.001). Histologically, the ameloblasts were still columnar but poorly organized and the nascent enamel was often non-homogeneous. Enamel formation was not seen in any second molars exposed to 12 μM NaF and 2 mg/mL of amoxicillin (or higher concentrations) compared with the presence of enamel in half of the controls (p < 0.001).

Conclusions

Amoxicillin and NaF dose dependently affect developing enamel of mouse molars in vitro and the effects are potentiative. The clinical significance of the results remains to be studied.     

Sodium fluoride mouthrinse used twice daily increased incipient caries lesion remineralization in an in situ model

Objectives

To investigate the remineralizing effects of fluoride mouthrinses used at different times and frequency in addition to fluoride toothpaste.

Methods

A randomized crossover single blinded study comprised 4 experimental phases of 21 days each. Twelve orthodontic volunteers were fixed with an orthodontic bracket containing an artificial carious enamel slab, which was from the same tooth in all 4 phases, and were randomly assigned to the following groups: (1) brushing with F toothpaste 2× per day (F- brush), (2) F- brush + rinsing with 0.05% NaF (F- rinse) after lunch, (3) F- brush + F-rinse before bedtime, and (4) F- brush + F- rinse 2× per day. Mean mineral gain after each phase was determined from mineral density profiles obtained using Micro-CT.

Results

The mean mineral gain in all treatments with F- brush and F-rinse were significantly greater than those in F- brush (p < 0.05). Moreover F- rinse 2× per day increased lesion remineralization more than F- rinse once a day.

Conclusions

The twice-daily use of 0.05% NaF mouthrinse combined with twice-daily regular use of fluoride toothpaste resulted in the greatest remineralization of incipient caries. These data indicate that rinsing frequency is a factor affecting the effectiveness of fluoride mouthrinse.

Clinical significance

The rinsing frequency of NaF mouthrinse, when used with fluoride toothpaste, also affects the remineralization. This finding, if confirmed by a clinical study, would lead to a new recommendation for fluoride mouthrinse used in high caries risk patients who could benefit from using it twice a day.     

Effect of sodium,amine and stannous fluoride at the same concentration and different pH on in vitro erosion

Objective

This study aimed to compare the effects 0.5% and 1% sodium, amine and stannous fluoride at different pH on enamel erosion in vitro.

Methods

Bovine enamel samples were submitted to a cyclic de- and remineralisation for 3 days. Each day, the samples were exposed for 120 min to pooled human saliva and subsequently treated with one of the fluoride solutions for 3 min: amine fluoride (AmF, 0.5% and 1% F⁻), sodium fluoride (NaF, 0.5% and 1% F⁻), each at pH 3.9 and 7.0, and stannous fluoride (SnF₂, 0.5% and 1% F⁻), at pH: 3.9. Additionally, two groups were treated with fluoride-free placebo solutions (pH: 3.9 and 7.0) and one group served as control (no fluoridation). Ten specimens each group were inserted in a so-called artificial mouth and eroded six times daily with hydrochloric acid (pH 2.6) for 90 s each intermitted by exposure to artificial saliva (1 h). After 3 days, enamel loss was analyzed profilometrically and evaluated statistically by ANOVA.

Results

Only the acidic 0.5% and 1% SnF₂ and 1% AmF solutions were able to reduce erosive enamel loss significantly, while all other solutions and placebos did not differ significantly from the control. Between the acidic SnF₂ and the 1% AmF solutions no significant differences could be detected.

Conclusion

At the same concentrations, acidic SnF₂ and AmF may be more effective than NaF to protect enamel against erosion.     

TiF4 and NaF varnishes as anti-erosive agents on enamel and dentin erosion progression in vitro

Objective

This study assessed the effect of fluoride varnishes on the progression of tooth erosion in vitro. Material and Methods: Forty-eight enamel and 60 root dentin samples were previously demineralized (0.1% citric acid, pH 2.5, 30 min), leading to a baseline and erosive wear of 12.9 and 11.4 µm, respectively. The samples were randomly treated (6 h) with a 4% TiF₄ varnish (2.45%F-, pH 1.0), a 5.42% NaF varnish (2.45%F-, pH 5.0), a placebo varnish and no varnish (control). The samples were then subjected to erosive pH cycles (4x90 s/day in 0.1% citric acid, intercalated with artificial saliva) for 5 days. The increment of the erosive tooth wear was calculated. In the case of dentin, this final measurement was done with and without the demineralized organic matrix (DOM). Enamel and dentin data were analyzed using ANOVA/Tukey’s and Kruskal-Wallis/Dunn tests, respectively (p<0.05).

Results

The TiF₄ (mean±s.d: 1.5±1.1 µm) and NaF (2.1±1.7 µm) varnishes significantly reduced enamel wear progression compared to the placebo varnish (3.9±1.1 µm) and control (4.5±0.9 µm). The same differences were found for dentin in the presence and absence of the DOM, respectively: TiF₄ (average: 0.97/1.87 µm), NaF (1.03/2.13 µm), placebo varnish (3.53/4.47 µm) and control (3.53/4.36 µm).

Conclusion

The TiF₄ and NaF varnishes were equally effective in reducing the progression of tooth erosion in vitro.     

Effect of tricalcium silicate (Ca3SiO5) bioactive material on reducing enamel demineralization: An in vitro pH-cycling study

Objectives

The aim of this study was to investigate the effect of Ca₃SiO₅ on reducing enamel demineralization under pH-cycling conditions.

Methods

Forty bovine enamel samples were treated under four conditions: group 1, double distilled water (negative control); group 2, 1000 ppm F (as NaF, positive control); group 3, Ca₃SiO₅ slurry; and group 4, Ca₃SiO₅–F slurry (Ca₃SiO₅ with 1000 ppm F aq.). All the specimens were treated with treatment materials 4 times each day. Samples in groups 1 and 2 were soaked in test solutions for 2 min and samples in groups 3 and 4 were painted in treatment slurry for 2 min. At times between treatments, they were immersed in citric acid solution 3 times a day and 15 s each time. All the procedures were repeated for 7 days. Knoop microhardness, scanning electron microscopy (SEM), X-ray diffraction (XRD) and atom force microscopy (AFM) were used to examine samples.

Results

After treatment for 7 days, enamels in all the groups were significantly softened. The extents of microhardness reduction were 52.3%, 28.5%, 28.5% and 20.2% for groups 1, 2, 3 and 4, respectively. Samples in the negative control group showed a typical acid etched pattern while enamels in other groups were relatively compact. There was no significant difference between samples treated with Ca₃SiO₅ and F. The combination of Ca₃SiO₅ with F showed the best effect on reducing enamel demineralization.

Conclusions

Ca₃SiO₅ is an effective material against enamel demineralization alone but in combination with F a better anti-demineralization effect may be obtained.     

Evaluation of fluoride release from experimental TiF4 and NaF varnishes in vitro

Fluoride varnishes play an important role in the prevention of dental caries, promoting the inhibition of demineralization and the increase of remineralization.

Objective

This study aimed to analyze the amount of fluoride released into water and artificial saliva from experimental TiF₄ and NaF varnishes, with different concentrations, for 12 h.

Material and Methods

Fluoride varnishes were applied on acrylic blocks and then immersed in 10 ml of deionized water and artificial saliva in polystyrene bottles. The acrylic blocks were divided in seven groups (n=10): 1.55% TiF₄ varnish (0.95% F, pH 1.0); 3.10% TiF₄ varnish (1.90% F, pH 1.0); 3.10% and 4% TiF₄ varnish (2.45% F, pH 1.0); 2.10% NaF varnish (0.95% F, pH 5.0); 4.20% NaF varnish (1.90% F, pH 5.0); 5.42% NaF varnish (2.45% F, pH 5.0) and control (no treatment, n=5). The fluoride release was analyzed after 1/2, 1, 3, 6, 9 and 12 h of exposure. The analysis was performed using an ion-specific electrode coupled to a potentiometer. Two-way ANOVA and Bonferroni''s test were applied for the statistical analysis (p<0.05).

Results

TiF₄ varnishes released larger amounts of fluoride than NaF varnishes during the first 1/2 h, regardless of their concentration; 4% TiF₄ varnish released more fluoride than NaF varnishes for the first 6 h. The peak of fluoride release occurred at 3 h. There was a better dose-response relationship among the varnishes exposed to water than to artificial saliva.

Conclusions

The 3.10% and 4% TiF₄ -based varnishes have greater ability to release fluoride into water and artificial saliva compared to NaF varnish; however, more studies must be conducted to elucidate the mechanism of action of TiF₄ varnish on tooth surface.     

A qualitative and quantitative investigation into the effect of fluoride formulations on enamel erosion and erosion-abrasion in vitro

Objectives

To investigate the effect of a single application of highly concentrated SnF₂ and NaF solutions and a NaF/CaF₂ varnish on human enamel subjected to hydrochloric acid erosion and tooth brush abrasion.

Methods

Forty enamel samples were prepared from human third molars and NaF (9500 ppm, pH 8.0), SnF₂ (9500 ppm, pH 2.6) solutions; Bifluorid10^® varnish (42,500 ppm, NaF 5%, CaF₂ 5%) and deionized water (control) was applied to the enamel. Following this three, six and nine cycles of erosion [1 cycle = erosion (0.01 M HCl, pH 2.2, 2 min) + artificial saliva (1 h, pH 7.0)] and erosion-abrasion [1 cycle = erosion (0.01 M HCl, pH 2.2, 2 min) + artificial saliva (1 h, pH 7.0) + abrasion (120 linear strokes in artificial saliva from Tepe medium soft brushes 200 g loading)] were carried out. The fluoride treated enamel was analysed using Knoop microhardness, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

Results

For erosion alone, there was significantly less microhardness reduction in the Bifluorid10^® group after three and six cycles of erosion (P < 0.05), however no other groups showed statistically different hardness (P > 0.05). The EDS analysis showed that only the Bifluorid10^® group had any detectable fluorine following erosion and erosion-abrasion (0.1 wt.% and 0.2 wt.% fluorine respectively). The surface fluorine was found to have been removed after erosion and erosion-abrasion for all other surface treatments. Although precipitates were observed after application of the surface treatments, following erosion-abrasion, no visible surface effects from any fluoride preparation remained.

Conclusions

Enamel surface precipitates from application NaF, SnF₂ solutions appear to not be able to provide protection against gastric erosion and tooth brush abrasion. The NaF/CaF₂ varnish provided limited protection against erosion but the role for such varnishes in gastric erosion and tooth brush abrasion remains uncertain.     

Effect of TiF4, ZrF4, HfF4 and AmF on erosion and erosion/abrasion of enamel and dentin in situ

Objective

This in situ study aimed to analyse the impact of different tetrafluorides (TiF₄, ZrF₄ and HfF₄) and AmF on erosion and erosion plus abrasion of enamel and dentin.

Design

Ten volunteers took part in this crossover and double-blind study performed in 8 phases of each 3 days. In each phase, 2 bovine enamel and 2 dentin specimens were fixed in intraoral appliances. One enamel and one dentin sample were pretreated once with TiF₄, ZrF₄, HfF₄ or AmF (all 0.5 M F) for 60 s, while the other samples remained unfluoridated and served as control. Then, all samples were subjected to either erosion only (4 times/day, 90 s) or to erosion and abrasion (2 times/day, 30 s/sample). Toothbrushing abrasion was performed 90 min after the first and last erosion with an electrical toothbrush and fluoridated toothpaste at 1.2 N. After 3 days, enamel and dentin loss was assessed by profilometry (μm) and analysed by repeated measures ANOVA and paired t-test (p < 0.05).

Results

All fluoride solutions reduced enamel and dentin loss significantly compared to the controls. Generally, eroded samples showed less wear than eroded and abraded samples. The protective potential of the fluorides was not significantly different and was only slightly, but mostly not significantly, decreased by abrasion. The protective effect of the fluoride solutions was similar in enamel and dentin.

Conclusion

Tetrafluorides and AmF are able to reduce erosion and erosion plus abrasion in situ and are almost equally effective.     

Calcium lactate pre-rinse increased fluoride protection against enamel erosion in a randomized controlled in situ trial

Objectives

This in situ trial study was designed to evaluate whether calcium (Ca) pre-rinse would increase the fluoride (F) rinse protection against enamel erosion.

Methods

Fifteen volunteers participated in this split-mouth, 3-phase, crossover design study wearing a palatal appliance containing four sterilized bovine enamel slabs, for 10 days. In the 1st phase, five participants followed protocol A: daily rinse with a Ca lactate (CaL, 150 mmol/L, 1 min), followed by F (NaF 12 mmol/L, 1 min). Other five participants followed protocol B: daily rinse only with F, while the remainders followed protocol C: no rinse (negative control). Appliances were removed from the mouth and one side of the palatal appliance was exposed to a daily erosive challenge (0.05 M citric acid, 90 s); the other side served as control (deionized water – no erosion). In the 2nd phase volunteers were crossed over to other protocol and in the 3rd phase volunteers received the remaining protocol not yet assigned. Specimens were evaluated for surface loss using an optical profilometer.

Results

Repeated-measures three-way ANOVA (p = 0.009) and Tukey's test showed that CaL pre-rinse followed by NaF rinse significantly decreased surface loss of enamel when performed prior to an erosive challenge in comparison with the condition in which NaF only was used.

Conclusions

Pre-rinse with CaL may increase the protection exerted by NaF against erosive wear.     

Assessing fluoride treatment and resistance of dental enamel to soft drink erosion in vitro: Applications of focus variation 3D scanning microscopy and stylus profilometry

Objectives

This study assesses the application of the focus variation 3D microscopy for the evaluation of dental erosion and fluoride treatment for prevention of enamel erosion in vitro.

Methods

Human dental enamel disks were treated with Prevident 5000^® (PV, n = 15) for 1 week and compared with a reference group (PN, n = 15) after orange juice erosion in vitro. A focus variation 3D scanning microscope (IFM) and a stylus type profilometer (SSP) were used to evaluate the erosion depths on enamel. 3D topographic images were taken with vertical resolutions of 0.1 and 0.02 μm. Scratch marks depths from SSP were measured on IFM images. Measurements were compared between the SSP and IFM and between the two study groups.

Results

The SSP and IFM measurements of eroded enamel surfaces showed similar trends between the two methods and between the two study groups. The SSP and the IFM measurements were statistically significantly different but correlated with each other. PV group showed consistently lower erosion depth than PN in all profile measures using both SSP and IFM. The stylus tip created scratch marks that were significantly different in depths between the eroded and the reference surfaces in both groups.

Conclusions

The focus variation 3D microscopy is a powerful tool in evaluating surface topography associated with enamel erosion and in assessing the treatment effects of anti-erosive therapies. Topical treatment with Prevident 5000^® significantly increased enamel resistance to erosion by orange juice and should be considered as a treatment choice in patients susceptible to acidic dental erosion.