Effect of a two-solution fluoride mouthrinse on remineralization of enamel lesions in vitro.

A previous study showed that a two-solution fluoride (F) rinse deposited significantly more loosely-bound F on the tooth surface than did a sodium fluoride (NaF) rinse with the same F concentration (12 mmol/L). In the present study, this experimental rinse was evaluated for its ability to cause remineralization of enamel lesions in an in vitro pH-cycling model. Caries-like lesions were formed in the enamel of extracted human molars by means of a pH 4 demineralizing solution. Fifty-one approximately 120-microns-thick sections containing lesions were randomly divided into (1) control, (2) NaF rinse, and (3) two-solution F rinse groups. With the cut surfaces protected, the control samples were immersed in a pH 7 remineralizing solution for 12 days, and twice daily the sections were also exposed to a pH 4 demineralizing solution for 30 min. Samples in the NaF group received an additional one-minute rinse with a NaF (12 mmol/L) solution twice daily. Samples in the two-solution rinse group received the rinse treatment with a 12 mmol/L F solution prepared by combination of a Na2SiF6 and phosphate-containing solution with a calcium solution just before use. The mineral contents of the lesions were assessed by quantitative microradiography. The results showed that (1) no significant de- or remineralization was detected in the controls; (2) a 46% decrease in mineral loss (delta Z) of the lesion was produced by the NaF rinses; and (3) a 94% decrease in delta Z and a 20-microns-thick, mineral-dense surface-coating were produced by the two-solution F rinse treatment.     

Elevated fluoride products enhance remineralization of advanced enamel lesions

Caries prevention might benefit from the use of toothpastes containing over 1500 ppm F. With few clinical studies available, the aim of this pH-cycling study was to investigate the dose response between 0 and 5000 ppm F of de- and remineralization of advanced (> 150 microm) enamel lesions. Treatments included sodium and amine fluoride, and a fluoride-free control. Mineral uptake and loss were assessed from solution calcium changes and microradiographs. Treatments with 5000 ppm F both significantly enhanced remineralization and inhibited demineralization when compared with treatments with 1500 ppm F. Slight differences in favor of amine fluoride over sodium fluoride were observed. The ratio of de- over remineralization rates decreased from 13.8 to 2.1 in the range 0 to 5000 ppm F. As much as 71 (6)% of the remineralized mineral was calculated to be resistant to dissolution during subsequent demineralization periods. With 5000-ppm-F treatments, more demineralizing episodes per day (10 vs. 2 for placebo) would still be repaired by remineralization.     

Influences of bicarbonate on processes of enamel subsurface remineralization and demineralization: assessment using micro‐Raman spectroscopy and transverse microradiography

In the present study, we investigated, using micro‐Raman spectroscopy (Raman) and transverse microradiography, the influence of bicarbonate [sodium hydrogen carbonate (NaHCO₃)] on the effects of carbonate ions in the mineral phase during demineralization (acid resistance test) of subsurface lesions. Baseline lesions were created by demineralizing bovine enamel, and specimens were then exposed to remineralization solutions containing 0, 5, or 50 mM bicarbonate. Acid resistance tests were performed on remineralized and sound enamel specimens. Raman spectra showed that carbonate and phosphate were incorporated into both surface layers and lesion bodies during remineralization in the presence of bicarbonate. Moreover, the presence of bicarbonate did not affect the rates of remineralization, although the average mineral profiles of remineralized enamel differed from those of sound enamel after acid resistance tests. Raman analyses enabled close evaluation of site‐specific characteristics of carbonate and phosphate in subsurface lesions. In conclusion, incorporation of carbonate and phosphate ions into enamel subsurface lesions during remineralization does not affect the magnitude of remineralization or acid resistance.     

pH-cycling of enamel and dentin lesions in the presence of low concentrations of fluoride

F-dentifrice usage causes slightly elevated fluoride levels in saliva. Therefore, the effects of permanent low fluoride concentrations versus daily dentifrice treatments were studied on enamel and dentin lesions in a pH-cycling model of alternating demineralization and remineralization. Groups received 1) no fluoride treatment. 2) 3 μM (0.06 ppm) F continuously present during re- and demineralization or 3) daily 5–min F-dentifrice treatments. Solutions were analyzed for changes in calcium and fluoride. Cumulative results (10 d) showed that for the non-fluoride group the dentin lesions increased, while for enamel lesions mineral uptake and loss were balanced. Addition of 3 μM F caused small, non-significant, enhancement of remineralization (1–7%). while demineralization was significantly inhibited for both tissues (9–23%). The daily dentifrice treatments resulted in a balance between mineral uptake and loss of dentin, due to inhibited demineralization (-33%) and enhanced remineralization (+ 79%). For enamel, the F-dentifrice treatments resulted in 43% reduction of demineralization, with no significant effect on remineralization. Fluoride loss from the 3 μM F cycling solutions was significant (up to 50%) and constant during the experimental period. Microradiographic analysis showed remineralization at the lesion front in enamel. In dentin, the lesion depth was increased in all groups, with concomitant mineral deposition in the surface region of the dentifrice group. Results indicate that slightly elevated fluoride levels may be considerably less effective in inhibiting lesion progression in dentin than in enamel, and suggest mineral uptake and loss to occur at similar depths for enamel lesions, while demineralization and remineralization occur at different depths in dentin.     

Remineralization effects of a two-solution fluoride mouthrinse: an in situ study

Results from previous studies show that a two-solution fluoride (F) rinse is significantly more effective than a NaF rinse of the same F content of 250 microg/g (ppm) in remineralizing enamel and root lesions in an in vitro cyclic de- and remineralization model. In the present study, the two-solution rinse and two NaF rinses with F contents of 250 ppm and 1000 ppm were evaluated in an intra-oral remineralization model. Caries-like lesions were formed in the enamel of extracted human molars with the use of a pH 4 demineralizing solution. Thin sections of the enamel (approximately 120 microm) containing lesions were prepared, and the mineral contents of the lesions were assessed by quantitative microradiography. With the cut surfaces protected by nail varnish, 3 enamel specimens were mounted with wax in the lingual areas of a removable mandibular appliance. The study used a randomized, crossover design with seven subjects. In each of the 3 legs of the study, subjects wore the appliances continuously except when eating, drinking, and brushing their teeth. Twice daily (after breakfast and before bedtime), the subjects received a one-minute rinse with 20 mL of (1) 250-ppm-F NaF rinse, (2) 1000-ppm-F NaF rinse, or (3) 228-ppm-F two-solution F rinse. At the end of the 14-day experimental period, the sections were retrieved, and the mineral contents of the lesions were again assessed quantitatively. The results show that both the 1000-ppm-F NaF and 228-ppm-F two-solution rinses produced a greater (p < 0.05) remineralization than did the 250-ppm-F NaF rinse. The remineralization produced by the two-solution rinse was not statistically different (p > 0.05) from that produced by the NaF rinse with 4x the F content (1000 ppm F).     

Comparison of solution- and gel-prepared enamel lesions--and in vitro pH-cycling study

A variety of methods has been employed to produce artificial caries-like enamel lesions. The aim of this paper was to use a pH-cycling regime to compare the de-/remineralization behavior of lesions prepared by two methods. Lesions were produced by use of either an acidified undialyzed gelatin system or a buffered solution. Enamel sections, each containing four lesions, were allocated to four groups (A, B, C, D) and subjected to a daily pH-cycling regime of 16-hour demineralization and eight-hour remineralization. Groups A & B contained gelatin-prepared lesions, whereas Groups C & D contained solution-prepared lesions. To the remineralizing solutions used in Groups B & D, 2 ppm fluoride was added. The mineral content in the lesions was assessed, by means of microradiography/microdensitometry, at baseline and at intervals for six weeks. The lesions in all four groups exhibited net demineralization. In terms of the total mineral lost from the lesion (the delta z parameter), the demineralization rates of the solution-prepared lesions were significantly greater than those of the corresponding gelatin-prepared lesions. All sections in the non-fluoride groups showed subsurface demineralization in initially sound enamel, whereas only one section in the fluoride groups showed an area of mineral loss. Laminations in the mineral content profiles were apparent only in Group D. The results of this study indicate that the method of lesion preparation affects the subsequent behavior of lesions when exposed to de- and remineralizing protocols.     

Fluoride dose response in pH-cycling models using bovine enamel

The aim of this study was to establish methodologies for verification of the fluoride solution dose-response relationship using bovine enamel and pH-cycling models. Six models of the cariogenic challenge were performed, varying the time of demineralization and pH, time of remineralization, composition of de- and remineralization solutions, frequency and time of application of treatment solutions and pH-cycling duration. For the evaluation of the fluoride effect on caries dynamics, two proposed models provided for improvement in standardization of methods leading to a higher level of precision, demonstrating a dose response between treatments with regard to surface microhardness and DeltaZ. For the evaluation of the fluoride effect on enamel remineralization, the addition of fluoride to the de- and remineralization solutions and the reduction of frequency and time of application of fluoride solutions led to a more suitable pH-cycling model.     

Enhanced enamel remineralization under acidic conditions in vitro

We conducted this study to test the hypothesis that acidic solutions undersaturated with respect to enamel and supersaturated with respect to fluorapatite can enhance enamel remineralization by reducing preferential remineralization of the outer lesion and promoting mineral ion penetration. We used quantitative microradiography to assess mineral changes in artificial surface-softened and subsurface lesions in human enamel in vitro, induced by such an acidic solution and by a neutral remineralizing solution. For surface-softened lesions, the extent of remineralization was similar for both solutions, although preferential remineralization of the outer lesion was observed with the neutral solution. For subsurface lesions, preferential remineralization of the outer lesion was not observed with either solution. However, the extent of subsurface lesion remineralization by the acidic solution was significantly greater than that observed with the neutral solution. Results obtained are noted to reflect inherent differences in lesion type and the properties of the solutions studied.     

Demineralization of human dentine compared with enamel in a pH-cycling apparatus with a constant composition during de- and remineralization periods.

A comparison was made between the demineralization of enamel and dentine with and without abraded surfaces. This was done in a pH-cycling experiment for different demineralization/remineralization ratios--in the range from 1:1 to 1:4--and for different fluoride additions (up to 2 ppm) in solution. A new automatic pH-cycling system, in which the de- and remineralization solutions have a constant composition during the de- and remineralization cycles, was used to create mineral loss in human dentine and enamel. Changes in mineral content were monitored by means of longitudinal microradiography. A linear correlation was found between the amount of mineral lost and the total demineralization time for both dentine and enamel. The demineralization rates were comparable for abraded enamel and dentine and for polished enamel and dentine, and this rate was roughly doubled by the removal of the outer surface for both tissues. This showed that the presence of the outer surface is equally important to dentine and enamel. Under the pH-cycling conditions used, a logarithmic relation was found between the addition of fluoride and the decrease in demineralization for both enamel and dentine. The inhibitory effect of fluoride on demineralization was most pronounced on abraded enamel, followed by pumice-polished enamel, abraded dentine and pumice-polished dentine. About 2 ppm fluoride was needed under the conditions used to stop enamel demineralization completely; in the case of dentine, however, this amount of added fluoride did not inhibit demineralization.     

Acid resistance of human enamel in vitro after bicarbonate application during remineralization

OBJECTIVES: The aim of this study was to investigate the acid resistance of subsurface enamel lesions remineralized with bicarbonate solutions during remineralization. METHODS: Two experiments were carried out. In experiment 1, mineral uptake and acid resistance of remineralized enamel lesions were analyzed quantitatively by microradiography for mineral changes. Bicarbonate solutions of 0.5, 5.0 and 50.0 mM were used. In experiment 2, to clarify acid resistance mechanisms, the pH changes in demineralizing solutions on the remineralized enamel surfaces were measured continuously. Only a bicarbonate solution of 5.0 mM was used. RESULTS: In experiment 1, the bicarbonate-treated groups were more acid resistant than the non-treated groups (p<0.05). However, no statistically significant difference was observed among the different concentrations of bicarbonate. In experiment 2, the pH rise of the bicarbonate group was greater than the other groups. CONCLUSION: It was found that bicarbonate-treated enamel lesions were resistant to acid. It would suggest that bicarbonate ions applied during remineralization may have penetrated into the subsurface lesions. These ions may have worked as buffer agents against the acid challenge and inhibited the decrease in pH.     

五倍子原液和中性液促进牙釉质人工龋再矿化作用的比较

目的 比较五倍子原液、中性液促进牙釉质人工龋的再矿化作用,探讨五倍子药液pH调节对其促进釉质龋再矿化作用的影响.方法 制备牛牙釉质人工龋标本,配制五倍子多酚化合物原液(pH 3.8)和五倍子多酚化合物中性液(pH 7.0).体外pH循环条件下分别使用NaF(NaF组)、去离子水(去离子水组)、五倍子多酚化合物原液(pH 3.8五倍子组)及中性液(pH 7.0五倍子组)处理龋标本.原子力显微镜下观察pH循环前、后各组标本再矿化层的形貌特点.显微放射照相检测pH循环前后标本的矿物丢失量及龋损深度.结果 pH循环后,原子力显微镜下两个五倍子组牙釉质表面均有明显的不规则突起物,在不规则排列、边界模糊的晶体表面散在分布了大量的颗粒.显微照相检测到NaF组、去离子水组、pH 3.8五倍子组、pH 7.0五倍子组样本的矿物丢失量变化百分率分别为(-38±14)%、(+43±7)%、(-10±4)%和(-11±4)%;龋损深度变化百分率分别为(-27.79±3.51)%、(+21.13±2.83)%、(-8.43±3.32)%和(-9.20±3.89)%,两个五倍子组均表现出整体矿物丢失和龋损深度减小,两组间整体矿物丢失量变化百分率和龋损深度变化百分率差异无统计学意义(P＞0.05).结论 五倍子原液与中性液促进早期釉质龋的再矿化作用无明显差异,五倍子药液pH调节对其促进再矿化作用无明显影响,用药过程中无需将瓦倍子原液调节至中性.

Abstract：

Objective To compare the effect of original and neutral G alla chinensis in promoting the remineralization of initial enamel carious lesions in vitro and to investigate the influence of Galla chinensiswith different pH on the promoting effect. Methods Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then the lesions were exposed to a pH-cycling regime for 12 days.Each daily cycle included 4 × 1 min application of one of four treatments: distilled and deionized water (DDW), aqueous solutions of NaF, acidic or neutral aqueous solutions of Galla chinensis extract(GCE). Before and after pH-cycling, the surface topography of the enamel slabs was observed by atomic force microscopy( AFM), and the integrated mineral loss and lesion depth of all the specimens were analysed by transverse mieroradiography. Results AFM images revealed the surface topographical changes of GCE- treated enamel. The percentage change of integrated mineral loss ( △IML% ) of the samples of NaF group,DDW group, pH 3.8 GCE group and pH 7.0 GCE group was ( -38 ± 14)%, ( + 43 ± 7 )%, ( - 10 ± 4)% and ( - 11 ± 4)% respectively. The percentage of lesion depth (△LD%) of the samples of NaF group,DDW group, pH 3.8 GCE group and pH 7.0 GCE group was( -27.79 ±3.51 )%, ( +21.13 ±2. 83)%,( -8.43 ± 3.32)% and ( -9.20 ± 3.89)% respectively. There was no significant difference in △IML%and △LD% between pH 3. 8 and pH 7. 0 GCE-treated enamel. Conclusions There is no significant difference in enhancement of remineralization of initial enamel carious lesions between the original and neutral Galla chinensis. Different pH Galla chinensis does not have obvious influence on remineralization. It is unnecessary to regulate the pH value of queous solution of Galla chinensis extract which acts as a anticaries agent.     

Effect of fluoride concentration on remineralization of carious enamel: an in vitro pH-cycling study

An in vitro pH-cycling experiment was carried out to investigate the effect of fluoride concentration on enamel demineralization and remineralization. Artificial caries lesions were formed in an acid-buffered solution and subjected daily to a 3-hour acid attack, a 5-min immersion in the test NaF solution (0, 1, 250, 500, 1,000, 1,750 and 2,500 ppm F), and to 21 h in an artificial saliva. Changes in mineral content were assessed weekly for 5 weeks using microradiography/microdensitometry. The lesions in the control group (0 ppm F) and the 1-ppm F group demineralized. Remineralization was significantly higher in the 500-ppm F group compared to the 250-ppm F group. However, higher fluoride concentrations did not produce any further significant increase in remineralization. Laminations were apparent in lesions subjected to the 250- and 500-ppm F solutions.     

Effect of addition of citric acid and casein phosphopeptide-amorphous calcium phosphate to a sugar-free chewing gum on enamel remineralization in situ

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been shown to remineralize enamel subsurface lesions in situ. The aim of this study was to investigate the effects of CPP-ACP in a fruit-flavoured sugar-free chewing gum containing citric acid on enamel remineralization, and acid resistance of the remineralized enamel, using an in situ remineralization model. The study utilized a double-blind, randomized, crossover design with three treatments: (i) sugar-free gum (2 pellets) containing 20 mg citric acid and 18.8 mg CPP-ACP, (ii) sugar-free gum containing 20 mg citric acid alone, (iii) sugar-free gum not containing CPP-ACP or citric acid. Ten subjects were instructed to wear removable palatal appliances, with 4 half-slab insets of human enamel containing demineralized subsurface lesions and to chew gum (2 pellets) for 20 min 4 times per day for 14 days. At the completion of each treatment the enamel half-slabs were removed and half of the remineralized lesion treated with demineralization buffer for 16 h in vitro. The enamel slabs (remineralized, acid-challenged and control) were then embedded, sectioned and subjected to microradiography to determine the level of remineralization. Chewing with gum containing citric acid and CPP-ACP resulted in significantly higher remineralization (13.0 +/- 2.2%) than chewing with either gum containing no CPP-ACP or citric acid (9.4 +/- 1.2%) or gum containing citric acid alone (2.6 +/- 1.3%). The acid challenge of the remineralized lesions showed that the level of mineral after acid challenge was significantly greater for the lesions exposed to the gum containing CPP-ACP.     

精氨酸牙膏对釉质早期龋再矿化作用的研究

目的 研究精氨酸牙膏对人牙釉质早期龋的再矿化效果。方法 制备人牙釉质龋标本,随机分为 3组：空白组（去离子水处理）,对照组（普通市售含氟牙膏处理,含质量分数 0.14%单氟磷酸钠）,实验组（精氨酸牙膏处理,含质量分数 0.14%单氟磷酸钠和 8%精氨酸）。经体外 pH循环 10 d,测量 pH循环前后各组样本的表面显微硬度,计算其差值;并通过偏光显微镜观察各组样本再矿化前后的形态学改变。pH循环结束后,脱矿处理 2h,测量其表面显微硬度,计算与 pH循环前的差值,评估再矿化处理对釉质抗酸能力的影响。采用酸蚀法测定各组的氟摄入量。结果 与对照组和空白组比较,实验组釉质表面的显微硬度、抗酸能力,以及氟摄入量均明显升高。偏光显微镜下观察,实验组病损深度明显变浅,且有表层下再矿化条带,而空白组与对照组病损无明显变化。结论 精氨酸牙膏能有效促进人牙釉质龋表层及表层下再矿化,在早期龋的防治领域具有较大的临床应用前景。     

Acid resistance of enamel subsurface lesions remineralized by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate

The aim of this clinical study was to investigate the acid resistance of enamel lesions remineralized in situ by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP: Recaldent). The study utilized a double-blind, randomized, crossover design with two treatments: (i) sugar-free gum containing 18.8 mg of CPP-ACP, and (ii) sugar-free gum not containing CPP-ACP as control. Subjects wore removable palatal appliances with insets of human enamel containing demineralized subsurface lesions and chewed the gum for 20 min 4 times per day for 14 days. After each treatment the enamel slabs were removed and half of each lesion challenged with acid in vitro for 8 or 16 h. The level of remineralization was determined using microradiography. The gum containing CPP-ACP produced approximately twice the level of remineralization as the control sugar-free gum. The 8- and 16-hour acid challenge of the lesions remineralized with the control gum resulted in 65.4 and 88.0% reductions, respectively, of deposited mineral, while for the CPP-ACP-remineralized lesions the corresponding reductions were 30.5 and 41.8%. The acid challenge after in situ remineralization for both control and CPP-ACP-treated lesions resulted in demineralization underneath the remineralized zone, indicating that the remineralized mineral was more resistant to subsequent acid challenge. The results show that sugar-free gum containing CPP-ACP is superior to an equivalent gum not containing CPP-ACP in remineralization of enamel subsurface lesions in situ with mineral that is more resistant to subsequent acid challenge.     

Comparison of laser fluorescence and longitudinal microradiography for quantitative assessment of in vitro enamel caries.

A new quantitative, non-destructive method using laser-induced fluorescence (LAF) was compared with longitudinal microradiography (LMR) for assessment of mineral changes in enamel slices using an in vitro caries model. Ten enamel slices, cut longitudinally from sound natural smooth surfaces of human teeth, were exposed to de- and remineralization in a pH-cycling model. The enamel slices were subjected to LAF and LMR measurements before and at 2, 4, 7, and 9 days of demineralization. For LAF, the average fluorescence radiance decreased during the demineralization period with 11% by day 2 and 49% by day 9. For LMR, the corresponding average loss of mineral content changed with 0.01 and 0.10 kg.m-2 over the same time period. The mineral losses in each individual enamel slice measured with the two techniques were strongly correlated, r = 0.97. The Spearman rank correlation coefficient for all LAF and LMR demineralization results was 0.86. The precision (coefficient of variation) for LAF was 3.1%, corresponding to 0.005 kg.m-2, and the repeatability error for LMR was 0.02 kg.m-2, indicating a lower discrimination threshold for LAF compared to LMR. It was concluded that the new, sensitive, non-destructive LAF method provides possibilities for further improvement in the quantification of initial caries lesions in natural smooth enamel surfaces for use in in vitro studies. Furthermore, it offers potential in in situ caries studies as well as a tool in the diagnosis of early enamel caries in vivo.     

In vitro model for evaluating the effect of child formula toothpastes on artificial caries in primary dentition enamel

PURPOSE: To determine if the in vitro 10-day pH-cycling model used for permanent teeth could be utilized to evaluate de/remineralization effects, on the enamel of primary teeth, of child formula toothpastes. METHODS: Sound extracted primary anterior teeth were coated with nail varnish, leaving a 1 mm-wide window prior to being placed in a demineralizing solution to produce artificial carious lesions in enamel. The teeth were subsequently cut longitudinally into 100 microm thick sections. The 72 specimens were randomly assigned to six groups. In Set 1 contained the specimens in Group a, which were treated with a pea-sized (0.32 g) quantity of non-fluoride toothpaste (First Teeth), and Groups b and c which were treated with half and pea-sized (0.16 g) quantities of fluoridated toothpaste (Colgate), and cycled for 10 days. The specimens in Set 2 (Groups A, B and C) were similarly treated but subjected to 7-day pH-cycling. RESULTS: After Day 8 the lesions in Set 1 extended into dentin and so could not be evaluated. Polarized light microscopy and microradiography were used to evaluate the lesions subjected to 7-day pH-cycling. Lesions in Groups A and B increased in depth and area by approximately 50%, while those in Group C increased in depth and area by 20%; however, no statistically significant differences occurred between the groups. If this model pH cycling is to be used for primary teeth, a reduction from 10 to 7 days in length should be considered.     

酪蛋白磷酸多肽钙氟磷复合体对牙釉质缺损再矿化的实验研究

目的　探讨 2 %酪蛋白磷酸多肽钙氟磷复合体 (caseinphosphopeptide amorphouscalciumfluoridephosphatecomplexes,CPP ACFP)溶液对人工牙釉质表层下缺损的再矿化作用。方法　从人第三磨牙切取 2 8块釉质片 (每片制备两条表层下釉质缺损 ) ,随机平分为 4组 ,每组分别于再矿化液中浸泡1、3、5、10d。将再矿化后的标本切片 ,显微放射照相 ,测定矿物质含量。结果　经 1、3、5和 10d再矿化后 ,矿化液分别取代人工牙釉质缺损丢失矿物质的 9 19%、14 2 7%、2 9 0 7%和 38 45 % (y =8 9316x0 63 47,R2 =0 932 2 ;y :再矿化率 ,x :时间 )。经One wayScheffe差异多因素分析比较发现 :每两组间再矿化率差异具有显著性。结论　实验室中CPP ACFP对人工牙釉质缺损有明显的再矿化作用     

Enamel remineralization by fluoride-releasing materials: proposal of a pH-cycling model

This study proposes a pH-cycling model for verifying the dose-response relationship in fluoride-releasing materials on remineralization in vitro. Sixty bovine enamel blocks were selected for the surface microhardness test (SMH1). Artificial caries lesions were induced and surface microhardness test (SMH2) was performed. Forty-eight specimens were prepared with Z 100, Fluroshield, Vitremer and Vitremer ? diluted - powder/liquid, and subjected to a pH-cycling model to promote remineralization. After pH-cycling, final surface microhardness (SMH3) was assessed to calculate percent recovery of surface microhardness (%SMHR). Fluoride present in enamel (μg F/mm3) and in the pH-cycling solutions (μg F) was measured. Cross-sectional microhardness was used to calculate mineral content (?Z). There was no significant difference between Z 100 and control groups on analysis performed on - %SMHR, ?Z, μg F and mg F/mm3 (p>0.05). Results showed a positive correlation between %SMHR and μg F/mm3 (r=0.9770; p=0.004), %SMHR and μg F (r=0.9939; p=0.0000001), ? and μg F/mm3 (r=0.9853; p=0.0002), ? and μg F (r=0.9975; p=0.0000001) and between μg F/mm3 and μg F (r=0.9819; p=0.001). The pH-cycling model proposed was able to verify in vitro dose-response relationship of fluoride-releasing materials on remineralization.     

Effects of a new titanium fluoride derivative on enamel de- and remineralization

The potential of a new titanium fluoride (TiF) derivative for caries prevention was tested in a pH-cycling model. Daily treatments with various concentrations (100, 250, and 500 p.p.m.) of TiF were compared with similar sodium fluoride (NaF) treatments given at the same pH. Bovine enamel lesions were subjected to 3 wk of pH cycling. The effects were assessed by analyzing calcium uptake and loss in the re- and demineralizing solutions, respectively, and by post pH cycling microradiographic analysis of the lesions. Treatments with NaF reduced calcium loss, enhanced calcium uptake, and induced overall lesion remineralization. Treatments with TiF derivative gradually caused almost complete inhibition of calcium loss and uptake (lesion 'arrestment'), irrespective of the concentration of the TiF derivative. To test the permanence of protection, sound enamel was pretreated with either TiF derivative or NaF, and demineralized for 14 d at pH 4.4 and 4.6. Calcium loss data show that up to 80% inhibition of demineralization could be achieved for the TiF derivative, which was not possible for NaF treatments. This inhibition was obtained through a combination of concentration and number of treatments. The TiF derivative is a promising agent for the prevention of dental caries, especially when aimed at preventing the onset of caries.