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.     

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。     

含氟涂料和含氟牙膏对釉面再矿化和抗酸作用的实验研究

目的：观察含氟涂料与含氟牙膏对釉质表面再矿化和抗酸作用。方法：取牛恒切牙制备釉质片;统一酸蚀脱矿后随机分为4组（n＝3）;分别为生理盐水（A组对照）、Duraphat含氟涂料（B组）、Fluor Protector含氟涂料（C组）、含氟牙膏规律处理（D组）;处理期间标本置于人工唾液孵育2周;再次酸蚀;各阶段均用显微硬度仪测定釉面显微硬度、扫描电镜观察釉面,图像分析电镜下釉面微孔隙面积差异;统计分析。结果：首次酸蚀后釉面明显脱矿。分组处理2周,A组釉面再矿化不明显;B组和C组釉面形成涂料保护层;D组釉面可见明显再矿化。再次酸蚀后：A组和D组显微硬度下降,B组和C组涂料保护层有明显抗酸作用。再次酸蚀后,A组和D组釉面微孔隙面积增加（P＜0．05）,但D组小于A组（P＜0．05）;B组、C组无显著变化（P＞0．05）。结论：含氟涂料在釉面形成保护层,具有抗酸蚀和促进釉面再矿化作用;含氟牙膏能促进脱矿釉面再矿化,抗酸作用较弱。     

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.     

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.     

Increased fluoride uptake and acid resistance by CO2 laser-irradiation through topically applied fluoride on human enamel in vitro

OBJECTIVES: The aim of the current in vitro study was to evaluate the effect of CO(2)-laser treatment immediately after applying amine fluoride solution on enamel. It was hypothesized that such a treatment would increase enamel fluoride uptake, and reduce dissolution rate and thermal surface alterations. METHODS: Fluoride uptake was determined in 40 human enamel sections randomly assigned to four groups (n=10), which were either left untreated (1), exposed to a 1% amine fluoride solution for 15s without irradiation (2), irradiated for 15s with a continuous-wave carbon dioxide laser (3), or laser-treated for 15s through the amine fluoride solution applied immediately beforehand (4). Fluoride uptake was determined with an ion selective electrode after acid dissolution of the specimens (surface and subsurface layers). For the determination of acid resistance, another 40 enamel sections were treated according to the above protocol. Acid resistance was determined in surface and subsurface layers by measuring eluted calcium upon 3% lactic acid exposure with atomic absorption spectrometry. Enamel surface alterations after laser irradiation were monitored using scanning electron microscopy. RESULTS: Laser irradiation through the fluoride solution led to significantly higher fluoride contents in the surface enamel layer compared to fluoride treatment alone or laser treatment alone (p=0.002). Laser treatment with or without fluoride resulted in an increased acid resistance of enamel specimens. Fewer surface alterations were observed upon SEM examination of specimens irradiated through the amine fluoride solution compared to counterparts treated with laser only. CONCLUSIONS: CO(2) laser light application through an amine fluoride solution may be useful and effective in the prevention of caries.     

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.     

Effect of xylitol:sorbitol on fluoride enamel demineralization reduction in situ

OBJECTIVES: To evaluate if sugar alcohols would reduce enamel demineralization enhancing the fluoride (F) effect. METHODS: A crossover in situ study was conducted in four phases, during which 10 volunteers were submitted to one of the treatments: (I) Distilled and deionized water, as a negative control; (II) F (226 microg F/ml as NaF; concentration used in commercial mouthrinse); (III) X:S (xylitol:sorbitol 1:3; final concentration 1.6M; 28% of sugar alcohols) and (IV) F+X:S (same final concentration that groups II and III). The volunteers wore palatal appliances containing four bovine enamel blocks of known surface microhardness (SMH), covered with a 'test plaque' of mutans streptococci, which were immersed during 1 min in one of the allocated treatment solutions simultaneously that the volunteers rinsed their mouths with the same solution. After the rinsing the appliances were put in the mouth and after 20 min a cariogenic challenge was made with 20% sucrose solution during 1 min. After further 45 min the 'test plaque' was collected for F analysis, enamel SMH was again determined and the percentage of change in relation to baseline was calculated; F uptake in enamel was also determined. RESULTS: With respect to all the analyses made, the group F+X:S did not differ from the F treatment (p>0.05) and the groups treated with F and F+X:S differed from the negative control (p<0.05). CONCLUSIONS: The results suggest that xylitol:sorbitol may not enhance the effect of fluoride present in mouth rinse on the reduction of enamel demineralization.     

Influence of carbamide peroxide on enamel fluoride uptake

OBJECTIVE: Aim of the study was to evaluate the influence of carbamide peroxide (CP) on enamel fluoride uptake by comparing enamel fluoride uptake from a 1% amine fluoride (AmF) gel with the fluoride acquisition from a 10% carbamide peroxide agent supplemented with 1% AmF. MATERIALS AND METHODS: Three enamel cylinders (4mm in diameter) were prepared from the buccal surfaces of 60 bovine incisors. One sample of each tooth was used for determination of baseline fluoride content of the respective tooth. The two remaining samples were allocated to the experimental series 1 or 2, respectively. Each series consisted of five experimental groups (A-E, n=12) and differed with respect to the length of the treatment period with the gels (A-D). The experimentally designed gels (pH 5.5) used in the study were as follows: A (10% CP), B (10% CP, 1% F(-) as AmF), C (1% F(-) as AmF), D (no CP, no F(-)) and were formulated on the same basis. The enamel samples were covered for 4h with the respective gel at 37 degrees C and were then transferred to artificial saliva for 20 h (series 1). The samples of group E served as controls and were not treated with a gel. In series 2, treatment with the gels and storage in saliva was conducted seven times. Finally, the samples were assessed for KOH-soluble and structurally bound fluoride. RESULTS: Only the enamel samples treated with the fluoridated bleaching gel (group B) and with the amine fluoride gel (group C) exhibited significant fluoride acquisition. Thereby, both gels showed significantly lower uptake in series 1 as compared to series 2. Both KOH-soluble and structurally bound fluoride acquisition was significantly higher in group C than in group B. CONCLUSION: Treatment with a carbamide peroxide gel supplemented with amine fluoride causes less fluoride acquisition in enamel than a pure amine fluoride gel. Under the conditions of the study, it is assumed that carbamide peroxide seems to influence enamel fluoride uptake.     

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.     

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.     

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.     

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.     

氟对托槽粘结强度及牙釉质抗酸性影响的实验研究

目的 探讨氟化物在正畸治疗中预防牙釉质脱矿的最佳使用方法.方法 制备正畸拔除的前磨牙96颗,随机分成4组(A,B,C,D),分别为对照组及酸蚀前、中、后用氟组,粘结托槽后,将每个样本分别放入装有2 ml酸性人工唾液的试管.分别在实验后第1、2、3、4周从每组样本中随机抽取6个,测定托槽抗剪粘结强度及酸性人工唾液中的Ca2 浓度,并对实验结果进行统计学分析.结果 酸蚀前、中、后用氟对托槽抗剪粘结强度及粘结材料残留指数均无显著性影响(P＞0.05),而对人工唾液中钙离子Ca2 浓度均有显著性影响(P＜0.05),Ca2 浓度顺序从大到小依次为:对照组、酸蚀前用氟组、酸蚀中用氟组、酸蚀后用氟组.结论 酸蚀前、中、后用氟对托槽的抗剪粘结强度及粘结材料残留指数均无显著性影响,且均可增加牙釉质的抗酸性,酸蚀后使用氟化物的效果最好.     

不同氟处理方法釉质表面超微结构观察

目的观察托槽粘结前应用不同方法氟处理以及去托槽后，釉质表面超微结构的变化。方法挑选因正畸需要而拔除的96颗双尖牙，随机分为对照组，酸蚀前加氟组，酸蚀液中加氟组，酸蚀后加氟组，每组牙釉质经酸蚀和不同方法氟处理后做扫描电镜观察并进行统计学分析。结果酸蚀中加氟组和酸蚀后加氟组釉质表面产生的反应物较多且去托槽后残留较多。结论酸蚀剂中加氟和酸蚀后加氟方法可能对固定正畸治疗中防止釉质脱矿有较好的效果。     

Efficacy of CPP-ACP fluoride varnish applied with and without acid etching in preventing enamel demineralization compared to light-curable fluoride varnish

ObjectivesTo compare efficacy of casein phosphopeptide (CPP)–amorphous calcium phosphate (ACP) fluoride varnish and light-curable resin modified glass ionomer fluoride varnish (FV) in preventing white spot lesions and evaluating acid etching prior to CPP-ACPFV application on its efficacy.Materials and MethodsMolars and premolars were transected and halves divided into four groups (n = 18/group): (1) resin-modified glass ionomer FV: etched and Clinpro-XT varnish (3M ESPE, Pymble, New South Wales, Australia) application; (2) CPP-ACPFV: MI varnish (GC America, Alsip, IL) application; (3) Etch+CPP-ACPFV: etched and MI varnish application; (4) Control: etched and no surface treatment. To simulate 12 weeks in an intraoral environment, samples were subjected to thermocycling, brushing, and pH cycling. Enamel surface microhardness was evaluated at baseline and after the simulated 12 weeks. Representative samples were also assessed using scanning electron microscopy (SEM).ResultsAt baseline there was no significant difference in microhardness among groups. After the simulated 12 weeks, all groups showed significant within-group differences (P < .001). Control showed the highest percentage loss of surface microhardness (89%), followed by CPP-ACPFV (58%), RMGIFV (51%), and Etch+CPP-ACPFV (24%). The control group had a significant decrease in microhardness compared to all experimental groups (P < .001). No difference was found between the RMGIFV and CPP-ACPFV varnish groups. The Etch+CPP-ACPFV group had significantly less decrease in microhardness compared to the RMGIFV (P < .001) and CPP-ACPFV groups (P < .001). With SEM, control samples showed signs of enamel surface damage, while experimental groups showed spherical particles on a relatively intact surface.ConclusionsRMGIFV and CPP-ACPFV are effective in reducing enamel demineralization. Acid etching the enamel surface prior to CPP-ACPFV varnish application increased its efficacy.     

氟化物涂膜对正畸固定矫治中牙釉质脱矿影响的SEM研究

目的：采用扫描电镜（SEM）观察氟化物涂膜对抑制离体牙牙釉质脱矿及促进再矿化的功效。方法：选择因正畸需要拔除的前磨牙15颗,经37％磷酸处理,制备人工釉质脱矿标本,并用氟化物涂膜进行表面处理。采用SEM对标本脱矿前（对照组）,脱矿后（脱矿组）以及氟化物涂膜治疗后（治疗组）的表面形貌进行观察分析。结果：对照组与脱矿组之间、脱矿组与治疗组之间形态学存在显著差异,而对照组与治疗组之间形态学差异相对较小。结论：氟化物涂膜可有效改善釉质脱矿后的牙齿脱矿形貌。     

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.     

氟保护漆对青少年固定正畸中釉质脱矿的影响

目的 探讨氟保护漆对青少年正畸患者固定矫治后釉质脱矿发生率的影响。方法 将80例16岁以下青少年固定正畸矫治患者随机分成2组：对照组40例（721颗）,对患者及家长进行口腔健康教育,不涂氟;实验组40例（742颗）,除了对患者和家长宣教外,戴用固定矫治器时及正畸期间每6个月用氟保护漆处理牙面。临床观察2年,对粘接托槽的牙齿观察其脱矿程度。结果 实验组中706颗牙脱矿指数为0,出现脱矿的有36颗,脱矿率为4.85%,未出现脱矿指数大于1的患牙。对照组中有604颗牙脱矿指数为0,出现脱矿的有117颗,脱矿率为16.23%,其中脱矿指数大于1的患牙有18颗。两组间差异有统计学意义（P<0.05）。结论 固定正畸患者戴用固定矫治器时及矫治期间使用氟保护漆能有效预防正畸牙釉质脱矿。     

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.