Effect of stannous and fluoride concentration in a mouth rinse on erosive tissue loss in enamel in vitro

The aim of this in vitro study was to investigate the influence of stannous and fluoride ion concentrations in various experimental solutions on erosion progression in enamel. Human enamel specimens were subjected to a cyclic de- and remineralisation procedure for 10 days, with six demineralisation periods per day, of 5 min each. Erosive demineralisation was performed with 0.05 M citric acid (pH 2.3). Except in the control group, specimens were treated for 2 min with test solutions after the first and the sixth demineralisation. Test solutions were: 1500 mg/L F⁻ groups: group 1: 2800 mg/L Sn²⁺; group 2: 2100 mg/L Sn²⁺; group 3: 1400 mg/L Sn²⁺; group 4: 700 mg/L Sn²⁺; 1000 mg/L F⁻ groups: group 5: 2100 mg/L Sn²⁺; group 6: 1400 mg/L Sn²⁺. All preparations were adjusted to pH 4.5. Tissue loss was determined profilometrically after the last experimental day. As expected, the greatest tissue loss (μm, mean ± S.D.) was found in the control group (72.6 ± 11.5). All test solutions were able to reduce tissue loss significantly (p ≤ 0.001). The reduction of tissue loss by test solutions depended on the ratio of the tin concentration to the fluoride concentration. Lowest values were obtained by the application of the solutions of group 1 (7.8 ± 2.5) and group 5 (7.6 ± 5.2). Solutions with high concentrations of tin and fluoride are very effective in reducing erosive tissue loss, and their efficacy increased with increasing ratios of tin to fluoride concentrations.     

Inhibition of tooth erosion by milk containing different fluoride concentrations: An in vitro study

Objectives

This in vitro study assessed the effect of milk containing different fluoride concentrations on tooth erosion.

Methods

Bovine enamel and root dentine specimens were treated with: (1) bovine whole milk with 0 ppm F; (2) 2.5 ppm F; (3) 5 ppm F; (4) 10 ppm F (all after erosion); (5) whole milk with 0 ppm F (before erosion); (6) NaF (0.05% F, positive control, after erosion) or (7) 0.9% NaCl (negative control, after erosion). The specimens were submitted to pH cycles (4× 90 s in soft drink) and treatments for 5 days. The specimens were immersed in the treatment solutions for 1 min (only at the first cycle each day) with further exposition to 1:1 milk:saliva slurry for 10 min. The tooth loss was measured using a contact profilometer and statistically analysed (p < 0.05).

Results

Rinsing with milk before erosive challenge significantly reduced tooth loss compared to negative control (67% and 24% reduction in dentine and enamel loss, respectively) and to milk after erosive challenge, only for dentine. The addition of fluoride to milk also reduced tooth loss compared to negative control, but with no significant differences among fluoride concentrations for enamel and dentine (μm), respectively: 0 ppm (3.63 ± 0.04 and 2.51 ± 0.53), 2.5 ppm F (2.86 ± 0.42 and 1.96 ± 0.47), 5 ppm F (2.81 ± 0.27 and 1.77 ± 0.44), 10 ppm F (2.03 ± 0.49 and 1.68 ± 0.59). There was a negative and significant correlation between [F] and the tooth loss.

Conclusions

Daily rinse with milk containing F is able to reduce both enamel and dentine erosion in vitro.

Clinical significance

Since the prevalence of dental erosion is steadily increasing, rinse with milk or its derivate might be an important strategy to reduce the progression of tooth erosion.     

Erosion-inhibiting potential of a stannous chloride-containing fluoride solution under acid flow conditions in vitro

Objectives

This study aimed to analyse the erosion-inhibiting potential of a single application of stannous chloride-containing fluoride solution on pellicle-covered enamel and dentine under constant acid flow conditions in vitro.

Design

Bovine enamel (n = 60) and dentine (n = 60) samples were exposed 1 h to the oral cavity of 4 healthy volunteers to allow for in situ pellicle formation. Pellicle-covered samples were randomly assigned to three groups (each n = 20 enamel and n = 20 dentine samples; 5 enamel and 5 dentine samples/volunteer) and treated once with a SnCl2/AmF/NaF (800 ppm Sn(II), 500 ppm F, pH 4.5) or a NaF solution (500 ppm F, pH 4.5) for 2 min or remained untreated (controls). Samples were eroded with hydrochloric acid (pH 2.6) in a small erosion chamber at 60 μl/min for 25 min. Calcium release into the acid was monitored in consecutive 30 s intervals for 5 min, then at 1 min intervals up to a total erosion time of 25 min using the Arsenazo III procedure. Data were statistically analysed by random-effects linear models (p < 0.05).

Results

The stannous chloride-containing fluoride solution reduced calcium loss of enamel and dentine to up to 6 min and 3.5 min, respectively. Calcium loss (% of control) amounted from 24 ± 7 (30 s) up to 93 ± 14 (6 min) in enamel and from 38 ± 13 (30 s) to 87 ± 15 (3.5 min) in dentine. The sodium fluoride solution was unable to reduce enamel and dentine erosion at any time point.

Conclusion

A single application of a stannous chloride-containing fluoride solution reduced enamel and dentine erosion up to 6 min and 3.5 min of constant acid flow, respectively.     

Protection of short-time enamel erosion by different tetrafluoride compounds

OBJECTIVE: This in vitro study aimed to analyse the protective effect of differently concentrated titanium (TiF(4)), zirconium (ZrF(4)) and hafnium (HfF(4)) tetrafluoride on enamel erosion. METHODS: Polished enamel surfaces of 36 bovine crowns were covered with tape leaving 4 enamel windows each 3mm in diameter exposed. The crowns were randomly assigned to six groups (each n=6) and pretreated with 4% TiF(4), 10% TiF(4), 4% ZrF(4), 10% ZrF(4), 4% HfF(4) or 10% HfF(4) for 4 min (first window), 10 min (second window) or 15 min (third window). The fourth window of each crown was not pretreated and served as control. Erosion was performed stepwise with 1% HCl (pH 2) in five consecutive intervals of each 15 s (total 75 s). Enamel dissolution was quantified by colorimetric determination of phosphate release into the acid. For each tooth, cumulative phosphate loss of enamel pretreated with one of the tetrafluoride compounds was calculated as percentage of the respective control and statistically analysed using two-way ANOVA. RESULTS: Enamel erosion was significantly reduced by TiF(4), ZrF(4) and HfF(4) application. Cumulative phosphate loss (mean % of control, 75s erosion) after 4-15 min application was significantly lower for 4% ZrF(4) (7-11%), 10% ZrF(4) (2-6%), 4% HfF(4) (11-9%) and 10% HfF(4) (12-16%) compared to 4% TiF(4) (42-27%) and 10% TiF(4) (54-33%). Only for 4% and 10% TiF(4), phosphate loss decreased with increasing duration of application, but also increased with increasing acid intervals. CONCLUSION: TiF(4), ZrF(4) and HfF(4) might protect enamel against short-time erosion, but protection was more enhanced by ZrF(4) and HfF(4) compared to TiF(4) application overtime.     

Influence of fluoride concentration and ethanol pre-treatment on the reduction of the acid susceptibility of enamel

Objective

To determine the association between KOH-soluble and structurally bound fluoride uptake and the erosion resistance of enamel, respectively. Additionally, the effect of enamel pre-treatment with ethanol before fluoridation was assessed.

Methods

Sixty bovine incisors (4 specimens/tooth) were randomly allocated to six groups (A-F). Samples 1 and 2 remained untreated, serving as control at baseline. Pre-treatment of the samples was performed for 5 min with 99% ethanol (groups A, B and C) or physiologic saline (groups D, E and F). Samples 3 and 4 were treated either with 0.5% (groups A and D), 1.0% (groups B and E) or 1.5% (groups C and F) fluoride solution. In samples 1 and 3, uptake of KOH-soluble and structurally bound fluoride was determined. Samples 2 and 4 were used for the determination of acid susceptibility by immersion in 1 ml HCl for 30 s. Calcium release into HCl was assessed by atomic absorption spectroscopy. Differences between the groups were calculated by unpaired t-tests (p < 0.05).

Results

Mode of pre-treatment showed no influence on fluoride acquisition. KOH-soluble and structurally fluoride uptake increased with increasing fluoride concentrations. Highest acid resistance was observed after treatment with 1% fluoride solution for both kinds of pre-treatment followed by 1.5% and 0.5% fluoride solution.

Conclusion

Dose-dependency was observed for enamel fluoride acquisition but not for acid resistance.     

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.     

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.     

Effect of fluoride compounds on enamel erosion in vitro: a comparison of amine, sodium and stannous fluoride

The aim of the study was to evaluate the relevance of cations in different fluoride compounds for their effectiveness as anti-erosive agents. Human enamel samples underwent a de- and re-mineralisation procedure for 10 days. Erosive demineralisation was performed with 0.05 M citric acid (pH 2.3) 6 x 2 min daily followed by immersion in the test solution 6 x 2 min each. Test solutions were: SnCl2 (815 ppm Sn; pH 2.6), NaF (250 ppm F; pH 3.5), SnF2 (250 ppm F, 809 ppm Sn; pH 3.5), amine fluoride (AmF, 250 ppm F; pH 3.5), AmF/NaF (250 ppm F; pH 4.3), and AmF/SnF2 (250 ppm F, 390 ppm Sn; pH 4.2). In the control group no fluoridation was performed. Mineral content was monitored by longitudinal microradiography. Finally, scanning electron microscopy was performed. The highest erosive mineral loss was found in the control group (48.0 +/- 17.1 microm). Mineral loss was nearly completely inhibited by AmF/SnF2 (5.7 +/- 25.1 microm; p < or = 0.001) and SnF2 (-3.8 +/- 14.4 microm; p < or = 0.001) treatments. Groups treated with SnCl2 (17.6 +/- 19.5 microm; p < or = 0.001) and NaF (13.2 +/- 21.7 microm; p < or = 0.001) showed a decrease in erosive mineral loss, AmF (41.6 +/- 16.0 microm) and AmF/NaF (27.7 +/- 28.4 microm) had no significant effect on erosion progression. The results indicate considerable differences between the fluoride compounds tested. Treatment with solutions containing SnF2 was most effective.     

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.     

Retention of KOH-soluble fluoride on enamel and dentine under erosive conditions--A comparison of in vitro and in situ results

OBJECTIVES: Aim of the study was to investigate the stability of CaF(2)-like precipitates on enamel and dentine under neutral or acidic conditions and to compare in vitro and in situ results. METHODS: Human enamel and dentine specimens were fluoridated (Elmex fluid, 5 min) and subjected to erosive demineralisation (Sprite light: 3/day each; 30 s in vitro, 2 min in situ) or stored under neutral conditions for 4 (in vitro) or 7 (in situ) days. KOH-soluble fluoride was determined using an ion selective electrode. Between the acid attacks, specimens were stored in remineralisation solution (in vitro) or retained in the oral cavity (four volunteers for enamel and dentine each). RESULTS: Initially, high amounts of KOH-soluble fluoride were gained (between 77.9+/-12.3 and 96.0+/-46.4 microg/cm2). Under neutral conditions in vitro, a significant decrease on enamel (16.2+/-5.0 microg/cm2) and dentine (18.6+/-10.5 microg/cm2) was found, which was more severe under acidic conditions (6.3+/-3.0 and 5.1+/-2.1 microg/cm2, respectively). Under in situ conditions, KOH-soluble fluoride was strikingly stable on enamel under neutral (42.3+/-12.6 microg/cm2) as well as under acidic conditions (54.1+/-17.4 microg/cm2). On dentine, the dissolution kinetics of KOH-soluble fluoride was similar to the in vitro conditions, but the loss was less severe (45.3+/-12.9 microg/cm2 under neutral and 8.8+/-6.4 microg/cm2 under acidic conditions). CONCLUSIONS: In vitro, more KOH-soluble fluoride was lost under erosive compared to neutral conditions. The intra-oral environment was considerably protective for CaF2-like precipitates especially on enamel.     

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.     

不同浓度氟泡沫对牙釉质表面显微硬度的影响

目的：观察不同浓度氟泡沫对脱矿牙釉质表面显微硬度值的影响。方法：将牙釉质块随机分为A，B两组，脱矿30min后在两组牙釉质表面分别涂布0．9％中性氟化钠氟泡沫和1．23％酸性氟磷酸盐氟泡沫4min，并在人工唾液中浸泡30min,24h后测定牙釉质表面显微硬度值，结果：两组不同浓度氟泡沫涂布后牙釉质表面显微硬度值均有显著提高，人工唾液浸泡30min和24h，涂布1．23％酸性氟磷酸盐氟泡沫组的牙南表面显微硬度值均高于0．9％中性氟化钠氟泡沫组，统计学检验30min时有显著差异，24h无差异。结论：两种浓度的氟泡沫均可使牙釉质表面显微硬度显著提高，1．23％酸性氟磷酸盐氟泡沫影响效果优于0．9％中性氟化钠氟泡沫。     

Effect of mineral supplements to citric acid on enamel erosion

The aim of this study was to evaluate the effect of mineral supplements to citric acid (1%; pH 2.21) on enamel erosion under controlled conditions in an artificial mouth. From each of 156 bovine incisors one polished enamel sample was prepared. The samples were divided among 13 experimental groups (n=12). In group 1 citric acid only was used (control). In groups 2-10 either calcium, phosphate or fluoride in various low concentrations was admixed to the citric acid. In groups 11-13 the citric acid was supplemented with a mixture of calcium, phosphate and fluoride. For demineralisation the specimens were rinsed with the respective solution for 1 min, immediately followed by a remineralisation period with artificial saliva (1 min). The specimens were cycled through this alternating procedure five times followed by rinsing for 8 h with artificial saliva. The de- and remineralisation cycle was repeated three times for each specimen interrupted by the 8 h-remineralisation periods. Before and after the experiments, the specimens were examined using microhardness testing (Knoop hardness) and laser profilometry. Hardness loss and enamel dissolution was significantly higher for the controls as compared to the remaining groups. Significantly lowest hardness loss for all groups was recorded for group 12 with admixture of calcium, phosphate and fluoride to citric acid. The significantly highest enamel loss was recorded for the controls compared to all other samples. Groups 3 and 4 revealed significantly lower and higher tissue loss compared to the remaining groups (2-13), respectively. The other groups did not differ significantly from each other. Modification of citric acid with calcium, phosphate and fluoride exerts a significant protective potential with respect to dental erosion. However, with the low concentrations applied enamel dissolution could not be completely prevented.     

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.     

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.     

局部应用Fe2+、F-对酸蚀釉质作用的体外研究

目的:评价硫酸亚铁、氟化钠溶液及两者共同作用时对酸蚀釉质的作用.方法:收集正畸拔除的新鲜完好前磨牙,制备80个样本,随机分为4组:C组(对照组,去离子水)、Fe2+组(15 mmol/L FeSO4)、F-组(1.23％NaF)、Fe2++F-组(15 mmol/L FeSO4+1.23％NaF).样本在各组实验溶液中浸泡1 min,然后交替进行6个脱矿-再矿化循环(共7d).1个完整周期包括:①在5 mL可口可乐(pH=2.58)中脱矿5 min;②在37℃、5 mL人工唾液中再矿化1h.酸蚀效果通过观察釉质表面形貌和测定表面显微硬度(SMH)进行评价,采用SPSS18.0软件包对数据进行单因素方差分析.结果:扫描电镜观察显示,铁、氟处理后,与C组相比,釉质表面粗糙程度显著减轻,各实验组釉质表面均有一定沉积物形成.碳酸饮料浸泡釉质后SMH明显下降.与C组相比,铁、氟制剂单独或联合处理釉质后SMH减少程度均显著降低(P＜0.001),但3个实验组间无显著差异.结论:铁、氟制剂单独或联合作用均可显著增强釉质抗酸蚀能力,但铁、氟联合并未出现叠加保护效果.     

Effect of fluoride varnish and gel on dental erosion in primary and permanent teeth

Objective

To assess the effect of a fluoride varnish and gel on the erosive wear of primary and permanent teeth.

Design

Sixty human primary (n = 30) and permanent (n = 30) enamel specimens were randomly assigned to one of the following groups: APF gel (1.23% F), NaF varnish (2.26% F), and control (no treatment). Fluoride gel was applied for 4 min and fluoride varnish for 24 h. Six daily demineralisation-remineralization cycles of 5 min of immersion in a cola drink (pH 2.3) and 30 min in artificial saliva were conducted during 7 days. All specimens were stored in artificial saliva between and after cycles. Surface Knoop microhardness (%SMHC) readings were performed at baseline, 48 h and 7 days. Data were tested using ANOVA and Tukey's tests (p < 0.05).

Results

For primary enamel, the mean %SMHC (±SD) after 48 h and 7 days was, respectively: gel (31.0 ± 14.4 and 36.9 ± 7.5), varnish (26.7 ± 9.5 and 38.3 ± 8.7), and control (35.8 ± 8.6 and 45.0 ± 8.6). For permanent enamel, such values were: gel (37.5 ± 7.7 and 27.8 ± 7.5), varnish (31.7 ± 9.6 and 27.4 ± 11.1) and control (48.6 ± 6.4 and 43.1 ± 6.4). In primary enamel, erosion inhibition by fluoride was not significant at 48 h (p = 0.203) and 7 days (p = 0.082). In permanent specimens, both products showed a significant effect (p < 0.001).

Conclusions

Both fluoride varnish and gel were able to inhibit erosive enamel loss but mainly in the permanent experimental groups. Primary and permanent enamel substrates reacted differently to both demineralization by a cola drink and remineralization by fluoridated compounds.     

Quantitative analysis of the impact of the organic matrix on the fluoride effect on erosion progression in human dentine using longitudinal microradiography

After an initial demineralisation, an intensive fluoridation is capable of inhibiting the erosive mineral loss in dentine completely, which might be related to the presence of the exposed organic dentine matrix. Aim of the present study was, therefore, to evaluate whether fluoride is also effective when the organic material is removed. The study was a cyclic de- and remineralisation model over 5 days in vitro. Samples from human coronal dentine were demineralised with citric acid (pH 2.3; 6 x 10 min per day) and intermittently stored in a remineralisation solution. Groups (n = 25 each) were defined as follows: Group 1: erosion only, no fluoridation; Group 2: erosion, alternately fluoridation with toothpaste (NaF; 0.15% F-; 3 x 5 min per day), mouthrinse (Olaflur/SnF2; 0.025 F-; 3 x 5 min per day) and gel (Olaflur/NaF; 1.25% F-; at Days 1 and 3 instead of one toothpaste application); Group 3: erosion and fluoridation as Group 2, organic material was continuously removed with collagenase (from Clostridium Histolyticum type VII, 100 U/ml) added to the remineralisation solution. Mineral content was monitored daily using longitudinal microradiogaphy. After fluoridation in the presence of collagenase, a linear increase in mineral loss (73.3 +/- 17.6 microm at Day 5) was observed, which significantly (P < or = 0.001) exceeded that of the control group (45.9 +/- 14.3 microm at Day 5). After fluoridation in the absence of collagenase, mineral loss ceased after the 2nd day (12.2 +/- 10.2 microm at Day 5) and was significantly lower compared to Groups 1 and 3 (P < or = 0.001). The results indicate that the dentine matrix is essential for the effectiveness of fluoride in dental erosion.     

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.     

Anti-erosive potential of amine fluoride, cerium chloride and laser irradiation application on dentine

Methods

Ninety-six dentine samples were prepared from human premolars and randomly assigned to eight groups (G1–G8). Samples were treated for 30 s with the following solutions: placebo (G1/G2), amine fluoride (Elmex fluid; G3/G4), cerium chloride (G5/G6) and combined fluoride/cerium chloride application (G7/G8). Samples of groups G2, G4, G6 and G8 were additionally irradiated with a carbon dioxide laser through the solutions for 30 s. Acid resistance was assessed in a six-time 5-min consecutive lactic acid (pH 3.0) erosion model and calcium release was determined by atomic absorption spectroscopy (AAS). Furthermore, six additional samples per group were prepared and subjected to EDS-analysis.

Results

In the non-irradiated groups, specimens of G1 (placebo) showed the highest calcium release when compared to the other treatments (G3, G5 and G7). The highest acid resistance was observed for G7. In G3, calcium release was lower than in G5, but higher than in G7. In general (except for the placebo groups), calcium release in the laser-irradiated groups was higher compared with the respective non-irradiated groups. EDS showed a replacement of calcium by cerium and of phosphor by fluoride.

Conclusion

The highest anti-erosive potential was found after combined cerium chloride and amine fluoride application. Laser irradiation had not adjunctive effect.