Effect of an experimental 4% titanium tetrafluoride varnish on dental erosion by a soft drink

OBJECTIVES: This in vitro study assessed the effect of an experimental 4%TiF(4) varnish on enamel erosion. METHODS: Sixty bovine enamel blocks were randomly allocated to each type of varnish: Duraphat-D (NaF, 2.26%F), Duofluorid-F (NaF, 2.71% F), TiF(4)-T (2.45%F) and no-fluoride-P. After application of the varnishes, the blocks were subjected to six sequential pH cycles (cola drink for 10 min and artificial saliva for 50 min, each) per day, during 4 days. After the pH cycles, the blocks were maintained in artificial saliva for 18 h. Enamel alterations were determined in the 2nd and 4th days, using profilometry (wear) and microhardness (%SMHC) tests. Data were tested using ANOVA and Tukey's tests (p<0.05). RESULTS: The mean %SMHC (+/-S.D.) at the 2nd and 4th day was, respectively, D (-77.26+/-5.04a and -88.59+/-5.11A), F (-76.79+/-7.82a and -88.78+/-6.10A), T (-88.28+/-3.19b and -92.04+/-2.54A,B) and P (-87.96+/-2.23b and -94.15+/-1.14B). The mean wear (microm+/-S.D.) at the 2nd and 4th day was, respectively, D (3.16+/-0.32a and 7.56+/-0.90A), F (3.35+/-0.78a,b and 7.92+/-0.98A), T (3.81+/-0.43b and 7.69+/-0.76A) and P (3.43+/-1.13a,b and 7.31+/-0.53A). CONCLUSIONS: The NaF varnishes reduced the softening, but had no effect on the reduction of the wear. The TiF4 varnish was not able to reduce the softening and wear.     

Effect of calcium pre-rinse and fluoride dentifrice on remineralisation of artificially demineralised enamel and on the composition of the dental biofilm formed in situ

Objective: This in situ blind crossover study investigated the effect of calcium (Ca) rinse prior to the use fluoride (F) dentifrice on remineralisation of artificially demineralised enamel and on the composition of biofilm. Design: During four phases of 14 days, 10 volunteers wore appliances containing two artificially demineralised bovine enamel blocks. Three times a day, they rinsed with 10 mL of Ca (150 mM) or placebo rinse (1 min). A slurry (1:3, w/v) of F (1030 ppm) or placebo dentifrice was dripped onto the blocks. During 1 min, the volunteers brushed their teeth with the respective dentifrice. The appliance was replaced into the mouth and the volunteers rinsed with water. The biofilm formed on the blocks was analysed for F and Ca. Enamel alterations were evaluated by the percentage of surface microhardness change (%SMHC), cross-sectional microhardness (% mineral volume) and alkali-soluble F analysis. Data were analysed by ANOVA (p < 0.05). Results: The use of the Ca pre-rinse before the F dentifrice produced a six- and four-fold increase in biofilm F and Ca concentrations, respectively. For enamel, the remineralisation was significantly improved by the Ca pre-rinse when compared to the other treatments. There was a significantly higher concentration of alkali-soluble F in enamel when the F dentifrice was used, but the Ca pre-rinse did not have any significant additive effect. Conclusions: According to our protocol, the Ca pre-rinse significantly increased biofilm F concentration and, regardless the use of F dentifrice, significantly enhanced the remineralisation of artificially demineralised enamel.     

Effect of iron on inhibition of acid demineralisation of bovine dental enamel in vitro

OBJECTIVES: Iron ions (Fe(2+)) have been shown to be cariostatic in many studies particularly by their ability to reduce bacterial metabolism. Nevertheless, the role of iron ions on dissolution of enamel is unexplored. The aim of the present study was therefore to investigate the protective effect of increasing concentrations (0-120mmol/L) of Fe(2+) on the dissolution of enamel. DESIGN: Enamel powder was subjected to acetic acid made with increasing concentrations with respect to FeSO(4)x7H(2)O. In order to determine the amount of enamel dissolved, the phosphate released in the medium was analysed spectrophotometrically using the Fiske-Subarrow method. Data were tested using Kruskall-Wall and Dunn's tests (p<0.05). The degree of protection was found to approach maximum at about 15mmol/L Fe(2+). Higher concentrations of Fe(2+) did not have an extra effect on inhibition of dissolution of enamel powder. In the next step, the protective effect of 15mmol/L Fe(2+) against mineral dissolution of the bovine enamel was evaluated using a simple abiotic model system. Enamel blocks were exposed to a sequence of seven plastic vials, each containing 1mL of 10mmol/L acetic acid. The acid in vial 4 was made 15mmol/L with respect to FeSO(4)x7H(2)O. The mineral dissolved during each challenge was thus determined by phosphate released as described above. Data were tested using two-way ANOVA (p<0.05). RESULTS: Lower demineralisation (around 45%) was found in vial 4 (with Fe) that continued stable until vial 7. CONCLUSIONS: Thus, our data suggest that Fe(2+) can be effective on inhibition of dissolution of enamel and that this effect may be durable.     

Effect of 4% titanium tetrafluoride solution on dental erosion by a soft drink: an in situ/ex vivo study

OBJECTIVE: This in situ/ex vivo study assessed the effect of titanium tetrafluoride (TiF(4)) on permanent human enamel subjected to erosion. DESIGN: Ten volunteers took part in this study performed in two phases. In the first phase (ERO), they wore acrylic palatal appliances containing two enamel blocks, divided into two rows: TiF(4) (F) and no-TiF(4) (no-F). During the 1st day, the formation of a salivary pellicle was allowed. In the 2nd day, the TiF(4) solution was applied on one row (ERO+F), whereas on the other row no treatment was performed (ERO+no-F). From 3rd until 7th day, the blocks were subjected to erosion, 4x per day. In the 2nd phase (no-ERO), the volunteers wore acrylic palatal appliances containing one enamel block, during 2 days, to assess the effect of TiF(4) only (no-ERO+F). Enamel alterations were determined using profilometry (wear), microhardness (%SMHC) tests, scanning electron microscope and microprobe analysis. The %SMHC and wear were tested using ANOVA and Tukey's post hoc tests (p<0.05). RESULTS: The mean of %SMHC and wear (microm) values (+/-S.D.) were, respectively: ERO+F -73.32+/-5.16(A)/2.40+/-0.60(a); ERO+no-F -83.49+/-4.59(B)/1.17+/-0.48(b) and no-ERO+F -67.92+/-6.16(A)/0.21+/-0.09(c). In microscope analysis, the no-F group showed enamel with honeycomb appearance. For F groups, it was observed a surface coating with microcracks. The microprobe analysis revealed the presence of the following elements (%) in groups ERO+F, ERO+no-F and no-ERO+F, respectively: Ca (69.9, 72.5, 66.25); P (25.9, 26.5, 26.06); Ti (3.0, 0, 5.93). CONCLUSIONS: The TiF(4) was unable to reduce dental erosion.     

Effect of compounds of Galla chinensis on remineralization of enamel surface in vitro

Objective

The aim of the study was to investigate the effect of chemical compounds of Galla chinensis on in vitro the remineralization of enamel surface.

Method

Bovine enamel blocks with in vitro produced initial lesions were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4×1 min applications with one of four treatments: Group A: 1000 ppm F aq. (as NaF, positive control); Group B: deionized water (DDW, negative control); Group C: 4000 ppm crude aqueous extract of G. chinensis (GCE); Group D: 4000 ppm gallic acid. The enamel specimens were analysed by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray microdiffraction (XRD).

Results

The morphology of surface enamel was different in each group. The mineral composition was identified as similar to hydroxylapatite, but the crystallite sizes of enamel in different groups were significantly different. In addition, the Ca/P ratios were significantly lower in GCE group.

Conclusion

GCE could affect the mineral ions deposit on the surface layer and then modified the remineralization of initial dental caries. The mechanism seems to be different between GCE and gallic acid.     

玻璃离子保护膜与氟保护漆对牙釉质脱矿的预防和再矿化作用

目的: 比较玻璃离子保护膜与氟保护漆对牙釉质脱矿的预防和再矿化作用。方法: 选择122颗正畸减数拔除的前磨牙,制成釉质块,随机选择2个,进行扫描电镜（SEM）观察,其余用于两部分实验。①釉质脱矿预防实验 （实验A）—选择60个釉质块,随机分为3组（n=20）,分别使用玻璃离子保护膜（A1组）、氟保护漆（A2组）,对照组（A3组）不予处理;②釉质再矿化实验（实验B）—选择60个釉质块,预脱矿72 h后,随机分为3组(B1、B2、B3,n=20),处理方法同预防釉质脱矿各组。实验A、B共6组样本均经人工脱矿液和人工唾液交替pH循环处理30 d。采用SEM观察釉质表面形貌,显微硬度计测定釉质表面显微硬度（SMH）变化,X线能谱分析仪分析釉质表面钙磷比。采用SPSS 26.0软件包对数据进行统计学分析。结果: 釉质脱矿预防实验,未作处理的牙釉质表面平坦、均匀,A1组釉质表面基本完整,A2组釉质表面可见大量片状沉积物,A3组呈现典型的脱矿导致的蜂窝状结构。各组间ΔSMH两两比较,A1组A2组>A3组(P<0.05)。釉质再矿化实验,SEM结果显示,B1、B2组均有沉积物附着于釉质表面,B3组釉质表面凹凸不平,呈蜂窝状。各组间ΔSMH两两比较,B1组>B2组>B3组(P<0.05)。钙磷比值依次为B1组>B2组>B3组(P<0.05)。结论: 玻璃离子保护膜和氟保护漆均可预防和治疗牙釉质脱矿,玻璃离子保护膜由于其耐磨、持久,具有更好的保护和再矿化作用。     

Effect of titanium tetrafluoride, amine fluoride and fluoride varnish on enamel erosion in vitro

This study aimed at evaluating the effect of 1 and 4% titanium tetrafluoride (TiF4) gels, amine fluoride (AmF) 1 and 0.25% and a fluoride varnish (FP) on the prevention of dental erosion. Two experimental groups served as controls, one with no pretreatment and another one pretreated with a fluoride-free varnish (FP-blanco). Dental erosion was modelled using bovine enamel samples submitted to alternate cycles of acid exposure in citric acid and remineralization in artificial saliva. Calcium loss of all samples involved in the study was quantified by atomic absorption spectroscopy and erosion depths were estimated. Two samples of each experimental group were also analyzed by white light confocal microscopy. The cumulative erosion depth (in mum) after 72 min was: TiF4 gel 1% 8.29 +/- 0.39; TiF4 gel 4% 8.27 +/- 0.55; AmF 1% 8.69 +/- 0.66; AmF 0.25% 8.86 +/- 0.33; FP 3.43 +/- 1.07; FP-blanco 14.86 +/- 1.59 and control 9.77 +/- 0.49. A statistically significant protective effect (p < or = 0.001) was found only for the group pretreated with the fluoride varnish. Within the limitations of an in vitro study it may be concluded that topical applications of the fluoride varnish tested have a protective effect on the prevention of dental erosion.     

EFFECT OF 4% TITANIUM TETRAFLUORIDE SOLUTION ON THE EROSION OF PERMANENT AND DECIDUOUS HUMAN ENAMEL: AN IN SITU/EX VIVO STUDY

This in situ/ex vivo study assessed the effect of titanium tetrafluoride (TiF₄) solution on erosion of permanent (P) and deciduous (d) human enamel. Ten volunteers wore acrylic palatal appliances containing 4 enamel samples, divided into two rows: TiF₄ and no - TiF₄ (control). Each row contained one deciduous and one permanent enamel sample. During the 1st day, formation of a salivary pellicle was allowed. At the 2^nd day, the 4% TiF₄ solution was applied on one row (TiF₄), while the other row remained untreated (control). From the 3^rd until the 7^th day, the samples were subjected to erosion by immersion in a cola drink for 5 min, 4 times/day. Enamel alterations were determined by microhardness testing (%SMHC). Data were analyzed using 2 two-way ANOVA and Tukey''s post hoc test (a=0.05). The mean %SMHC (±SD) amounted to: P (TiF₄ - 73.32 ± 5.16 and control - 83.49 ± 4.59) and d (TiF₄ - 83.01 ± 7.41 and control - 75.75 ± 2.57). In conclusion, the application of 4% TiF₄ solution reduced the softening of permanent enamel but not of deciduous enamel significantly. However, no significant differences were detected between the permanent and deciduous enamel when the factor substrate was considered.     

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 topically applied silver compounds on the demineralisation of hydroxyapatite

ObjectivesThis study investigates the demineralization inhibitory mechanisms of AgNO₃, AgF and silver diamine fluoride (SDF) using a previously used hydroxyapatite (HAP) caries demineralization model system.MethodsHAP discs were allocated into three groups (n = 3) and immersed in demineralization solution (buffered pH 4.0, 0.1 mol/L acetic acid) for 4 h. Each disc was treated topically with either 3.16 M AgNO₃, 3.16 M AgF or 3.16 M SDF using a micro-brush. The discs were then demineralized for a further 4 h. Calcium, silver, and fluoride ion selective electrodes (ISEs) were used to monitor the changes in each ion concentration at 1 min intervals throughout. Demineralization inhibition was calculated as the percentage reduction in the rate of calcium ion loss from HAP (PRCL_HAP). Characterization of similarly treated HAP powder was carried out with Magic Angle Spinning-Nuclear Magnetic ResonanceResultsThe mean PRCL_HAP for each treatment group was; AgF (72.3 + 4.8%), SDF (69.7 + 5.3%) and AgNO₃ (14.9 + 2.7%). Ag₃PO₄ was detected in all HAP powders. CaF₂ and fluorohydroxyapatite (FHA) were detected only in powders treated with either AgF or SDF.The demineralization inhibitory efficacy of topically applied AgNO₃ results from the formation of a Ag₃PO₄ barrier. Whereas, the demineralization inhibitory efficacy of topically applied AgF, and SDF, results from the formation of a barrier composed of Ag₃PO₄, CaF₂, and FHA.SignificanceIn addition to their anti-microbial properties, clinical topical application of silver compounds for caries preventative treatment is due to their ability to form acid-resistant barriers composed of silver phosphate. When fluoride is present, this barrier also contains CaF₂ and FHA, additionally protecting the mineral.     

In situ effect of sodium fluoride or titanium tetrafluoride varnish and solution on carious demineralization of enamel

This study evaluated the effect of titanium tetrafluoride (TiF(4)) formulations on enamel carious demineralization in situ. Thirteen subjects took part in this cross-over, split-mouth, double-blind study performed in three phases of 14 d each. In each subject, two sound and two predemineralized specimens of bovine enamel were worn intra-orally and plaque accumulation was allowed. One sound and one predemineralized specimen in each subject was treated once with sodium fluoride (NaF) varnish or solution (Treatment A); TiF(4) varnish or solution (Treatment B); or placebo varnish or no treatment (Treatment C). The initially sound enamel specimens were exposed to severe cariogenic challenge (20% sucrose, eight times daily for 5 min each time), whereas the predemineralized specimens were not. Eleven subjects were able to finish all experimental phases. The enamel alterations were quantified by surface hardness and transversal microradiography. Demineralization of previously sound enamel was reduced by all test formulations except for the NaF solution, while both TiF(4) formulations were as effective as NaF varnish. For the predemineralized specimens, enamel surface hardness was increased only by TiF(4) formulations, while subsurface mineral remineralization could not be seen in any group. Within the experimental protocol, TiF(4) was able to decrease enamel demineralization to a similar degree as NaF varnish under severe cariogenic challenges, while only TiF(4) formulations remineralized the enamel surface.     

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 iron on acid demineralisation of bovine enamel blocks by a soft drink

OBJECTIVES: The aim of this study was to evaluate, in vitro, the effect of iron on the acid demineralisation of bovine enamel blocks by a soft drink. DESIGN: Twenty-four blocks of bovine enamel were randomly assigned to two groups (experimental and control), which were exposed to 4 cycles of demineralisation in Coke containing or not 10 mmol/L of iron, respectively, and another 4 cycles of remineralisation in artificial saliva. The softening of enamel was evaluated by % superficial microhardness change (SMHC) and wear analysis. Data were analysed using t-test (p<0.05). RESULTS: With regard to %SMHC, the experimental group presented average values (+/-S.E.) of -85.3+/-0.9, that were significantly higher (t=4.7, p<0.01) than the ones observed for control group (-76.7+/-1.6). The experimental group presented a mean wear (+/-S.E.) of 2.3+/-0.2 microm, that was significantly lesser (t=3.7, p<0.01) than the one observed for the control group (3.5+/-0.2 microm). CONCLUSIONS: According to this protocol, iron at 10 mmol/L significantly reduced the wear, but significantly enhanced the %SMHC of enamel blocks submitted to erosion by Coke.     

Caries susceptibility of human fluorosed enamel and dentine

OBJECTIVE: Objective of our laboratory study was to determine the impact of dental fluorosis severity on the formation of caries in the human enamel and dentine. MATERIALS AND METHODS: Thirty-three human molars were grouped according to modified Thylstrup-Fejerskov index (TFI) into normal (N, TFI 0), mild fluorosis (ML, TFI 1-3) and moderate fluorosis (MD, TFI 4-6). Three mesio-distal sections were made in corono-apical axis of the tooth, giving enamel and dentine samples. They were embedded in an epoxy resin, and polished. Half of the polished surface was covered with an acid resistant varnish and immersed in standard acidified buffer solution (pH 4.5) for 48 h to create artificial caries lesions. They were treated with 5% NaOCl for 45 min and sectioned longitudinally along the center into two halves. Cut surfaces were polished and observed under a confocal laser scanning microscope for depth of demineralization. Morphology of the demineralized zones was observed under a field emission scanning electron microscope (FE-SEM). Data were analyzed using one-way ANOVA and Sheffe test (p=0.05). RESULTS: Statistically significant difference in depth of demineralization was found between N and MD groups (p=0.046) in the enamel, and between N and ML (p=0.002), N and MD (p<0.001), ML and MD (p=0.029) in dentine. FE-SEM observation of the normal enamel showed direct dissolution with large fissures. Spongy appearance of intertubular dentine gradually disappeared from N to MD. CONCLUSIONS: Moderately fluorosed enamel showed a significant caries resistance. In contrast, mild and moderately fluorosed dentine was significantly caries susceptible in vitro.     

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.     

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.     

氟化物涂膜的临床应用

氟化物的防龋作用较为明显,目前临床上应用的各种氟化物剂型多有其缺点,严重影响了氟化物的临床应用。氟化物涂膜作为一种局部应用氟化物缓释剂型,由于其独特的剂型特点,在防龋、治疗牙本质过敏症和预防正畸过程中牙釉质白斑的发生等多个方面都有着不可替代的优点,因此在许多国家氟化物涂膜已取代了氟化物凝胶的应用。本文就氟化物涂膜的临床应用情况及功能特点作一简要综述。     

In situ de- and remineralisation of enamel in response to sucrose chewing gum with fluoride or non-fluoride dentifrices

Objectives: Enhancement of the remineralisation of artificial enamel lesions has been observed in an intraoral model whether subjects chewed gum sweetened with a non-cariogenic sweetener such as sorbitol [1, 2, 3] or sucrose [4] after meals or snacks, and with use of a conventional (1500 ppm F) fluoride dentifrice. Since most of the clinical surveys which have shown the potential cariogenicity of sucrose chewing gum [5] were conducted before use of fluoridated dentifrices became widespread, the effect of fluoride dentifrice on de- and remineralisation of artificial lesions in enamel in response to chewing sucrose-sweetened gum has been examined with the aim of attempting to resolve this apparent discrepancy. Methods: Subjects wore an intraoral device bearing an enamel lesion and chewed one piece of sucrose gum for 20 min after each of three meals and two snacks daily for two 3-week periods, during which they used a dentifrice containing either 0 or 1500 ppm F in a double-blind, cross-over design. Measurement of the mineral content of the lesions was determined by microradiography or polarised light microscopy. Results: It was found that remineralisation tended to occur with 1500 ppm F dentifrice, but demineralisation with non-F dentifrice; the difference in enamel mineral content between the two periods was significant (P<0.05). Conclusions: The results indicate that the potential cariogenicity of sucrose-containing chewing gum may indeed be negated by the use of a conventional fluoride dentifrice.     

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。