Fluoride release and uptake by four new fluoride releasing restorative materials

The present study compared the initial fluoride release and release following refluoridation of a conventional glass-ionomer Ketac-Molar (ESPE), a resin-modified glass-ionomer, Vitremer (3M), and two compomers F-2000 (3M) and Hytac (ESPE). Fifteen test specimens were prepared for each brand and immersed in deionized water. The fluoride released was measured every 2 days for 22 days. Refluoridation of the test specimens was done with solutions of 0.02, 0.04 and 0.2% NaF for 5 min on days 22, 30, 38 and 46. The fluoride released from recharged specimens was measured every 2 days until day 54. The fluoride release was highest during the first days after preparation, after which it decreased sharply and then more slowly. The four materials became 'recharged' with fluoride following repeated fluoride exposure in solution, the 0.2% solution being the most effective. From a clinical point of view, the results from this study imply that all the restorative materials tested may act as intra-oral devices for the controlled slow release of fluoride at sites at risk of recurrent caries. Fluoride release and uptake by four new fluoride releasing restorative materials.     

Fluoride varnishes and caries development in primary tooth enamel: an in vitro study

This in vitro study evaluated the effect of fluoride varnishes on caries development in primary tooth enamel using polarized light microscopic techniques. A total of forty extracted or exfoliated primary teeth with intact, caries-free smooth surfaces underwent a fluoride-free prophylaxis and soft tissue were assigned to one of the following groups: 1) duraphat (5 percent sodium fluoride, vanish, Colgate, n=10); 2) Duraflor (5 percent sodium fluoride, Pharmascience, n = 10); 3 Cavity Shield (5 percent sodium fluoride varnish, Omni, n=10); and 4) Control (n=10). An acid-resistant coating was applied to the specimens leaving an exposed window of sound enamel (5mm x 1mm). The fluoride varnishes were applied to the primary teeth according to the manufacturer's recommendation. Following thermocycling (500 cycles, 5-50 degrees C) of the fluoride varnish-treated and control teeth, a fluoride-free pumice toothbrushing was performed to remove visible and macroscopically (dissecting microscope at 16x) detectable fluoride varnish. An acid resistant coating was reapplied where necessary, leaving the fluoride varnish treated sound enamel window exposed. Following in vitro caries formation (2.2mM Ca, 2.2mM PO4 50mM acetic acid, 0.5ppm fluoride, pH 3.90), longitudinal sections (5 per specimen) were obtained and evaluated by polarized light microscopy for mean lesion depth. Comparisons were made among treatment and control groups.     

Inhibition of demineralization in vitro around fluoride releasing materials

Replacement of restorations because of secondary caries is a continuing problem in restorative dentistry. This investigation assessed the capacity of fluoride-releasing restorative materials to resist caries in vitro when used in roots. Class 5 cavities were prepared in buccal and lingual surfaces of 30 extracted premolars and restored with one of three polyacid modified resin composites (F-2000, Hytac and Compoglass F), a resin modified glass-ionomer cement (Fuji II LC) a conventional glass ionomer (Ketac-Fil), and a resin composite (Z-100). After 5 weeks in an acid gel for caries-like lesion formation, the teeth were sectioned longitudinally and examined with polarized light. The results showed that restoration of caries with polyacid modified resin composites and resin modified glass ionomer cements may be of great importance in the prevention of secondary caries around the restorations in roots. Clinical Relevance Light cured fluoride-releasing restorations may inhibit caries-like lesions. Inhibition of demineralization in vitro around fluoride releasing materials.     

The anti-cariogenic potential of xylitol in comparison with sodium fluoride in rat caries experiments

Previous rat caries experiments in our laboratory demonstrated an anti-cariogenic and most probably a remineralizing effect of xylitol. The purpose of the present study was to compare the caries-inhibiting property of xylitol and fluoride in drinking water. The study consisted of two experiments with Osborne-Mendel rats, superinfected with S. mutans. In the first experiment, the rats were fed ad libitum a cariogenic diet containing 20% sucrose and 5% glucose (diet SSP 20/5) and tap water containing 0%, 2%, or 4% xylitol. An additional control group was fed diet SSP 20/5 supplemented with 5% xylitol. In the second experiment, the rats were also fed diet SSP 20/5, but received tap water, demineralized water (both containing less than 0.1 ppm F-), or tap water containing 10 and 40 ppm fluoride. Some animals in the 4% xylitol drinking water group showed a mild osmotic diarrhea for the first four days and a retarded increase in body weight of limited duration. S. mutans colonized to a similar level in all groups of both experiments. Fluoride as well as xylitol in the drinking water reduced the fissure caries scores significantly. However, 10 and 40 ppm fluoride had a more pronounced inhibiting effect on the caries experience than did 4% xylitol in the drinking water or 5% xylitol in the diet.     

Ion releasing direct restorative materials: Key mechanical properties and wear

ObjectivesTo investigate the depth of cure (DoC), fracture toughness (K_IC) and wear of ion releasing resin-based composite (RBC) restorative materials.MethodsTwo ion releasing RBCs, Activa (ACT) and Cention-N (CN) were compared to a conventional RBC (Z350) and a resin-modified glass ionomer cement (Fuji-II-LC). The DoC was measured in a 10-mm deep semi-circular metal mold with a 2-mm internal radius (n = 8). The molds were irradiated from one end for 20-s. The Knoop hardness (KH) was measured at 0.5-mm intervals from the surface after the specimens had been stored at 37 °C for 24-h. To measure the K_IC, single-edge-notched specimens (n = 15/group) were prepared (25×5x2.5-mm) for a 3-point bending test and then stored for either 1 or 30-days in water at 37 °C. Disk-shaped specimens (n = 10) were subjected to 250,000-load cycles of 49-N using a chewing simulator against spherical steatite antagonists. DoC and wear data were analyzed by one-way ANOVA and Tukey post hoc tests (p ≤ 0.05). K_IC data were analyzed by two-way ANOVA and one-way ANOVA, and the Tukey post hoc test (p ≤ 0.05). In addition, an independent t-test was used to determine if storage time had any effect (α = 0.05) on the K_IC of each material.ResultsMaximum hardness value was the highest for Z350 and the lowest for ACT. The depth at which 80% of the maximum KH, was the highest for CN (9.2 mm) and the lowest for Z350 (2 mm). All tested materials met the manufacturers’ claims for DoC. After 1-day, the highest K_IC values were recorded for ACT and the lowest for Fuji-II-LC. Water storage (30-days) significantly reduced the K_IC value for all materials except Fuji-II-LC. The highest wear rate values were recorded for CN followed by ACT.SignificanceAll tested materials met their manufacturers’ claims for DoC. Water storage for 30-days significantly reduced the fracture toughness for ACT and CN. Wear was significantly higher for ACT and CN.     

Fluoride release from orthodontic bonding materials. An in vitro study

Decalcification of enamel continues to be a problem with fixed orthodontic appliances. An orthodontic bonding composite is now available which claims to release fluoride, although there are no data to substantiate this claim. Fluoride release from this new material (DIRECT) was measured and compared with two other orthodontic bonding materials. The amount of fluoride released was very small and unlikely to have a therapeutic effect.     

六种牙齿充填修复材料的释氟与再充氟性能研究

目的 评价6种牙齿充填修复材料的释氟和再充氟性能,以期为临床选择和应用提供参考.方法 选择材料A(FujiⅦ玻璃离子水门汀)、材料B(FujiⅡLC光固化玻璃离子水门汀)、材料C(Beautifil离子体复合树脂)、材料D(Compoglass F复合体)、材料E(Charisma普通复合树脂)及材料F(实验Ⅰ型释氟性复合树脂)作为实验材料,制备直径10 mm、厚1 mm的圆片,每组10个试样.每个试样浸于5 ml去离子水中,用氟离子选择电极测定浸出液氟离子量,浸泡1～7d每天测定,8～28d3d测定1次,计算每日释氟量.于浸泡28 d后用氟化泡沫对试样充氟4min,继续测定试样每日释氟量,连续测定7d;再充氟并测定氟释放7d,重复3次.结果 浸泡1d后所有材料均表现最大的释氟量,材料A释氟量最大[(99.68±15.21) μg·cm-2·d-1],其次为材料B[(37.12±1.67) μg·cm-2·d-1],再次为材料F和D[分别为(22.93±1.53)和(15.28±0.70) μg·cm-2·d-1],材料C和E释氟量较小[分别为(2.40±0.52)和(0.11±0.02) μg·cm-2· d-1],各组间差异有统计学意义(P＜0.05).浸泡2d后释氟量显著下降,随后(7～ 28 d)释氟量下降缓慢;浸泡1～28 d内,材料A和B的释氟量始终大于其他材料(P＜0.01),其次是材料D和F,显著大于材料C和E(P＜0.01).所有材料充氟1d后的释氟量均较充氟前显著增加,形成释氟高峰,充氟2d后的释氟量又显著下降.充氟1d后材料A的释氟量超过40 μg· cm-2·d-1,大于其他材料(P＜0.01);其次是材料B,释氟量超过25 μg· cm-2·d-1,大于除A外的其他材料(P＜0.01);材料C、D、F释氟量相近,在15～ 20μg·cm-2·d-1之间;材料E释氟量较小,＜1.5 μg· cm-2·d-1.结论 玻璃离子水门汀类材料的释放及再充氟能力最强,其次是复合体和释氟性复合树脂,离子体复合树脂释氟能力小,但其再充氟能力与复合体和释氟性复合树脂相当,普通复合树脂的释氟及再充氟能力均较小.     

Fluoride metabolism in children and caries prevention

Basal mineral elements content in superficial dental enamel layers and daily urine fluoride excretion have been investigated in children using water with various level of this trace element. The investigation was carried out before and after sodium fluoride intake in the doses 1.1-1.6 mg/day. The results give evidence that differential approach to dental caries prevention with fluoride is required.     

Fluoride and caries prevention: 1. Scientific rationale

In order to achieve the greatest clinical benefit from the use of fluoride, we must understand its mechanism of action, so that fluoride can be given at the right time, by the best route, at the optimum dosage and in the most suitable form. The first article in this two-part series reviews the scientific rationale behind the use of fluoride. Part 2 will illustrate fluoride therapy in practical terms, by examining eight clinical cases.     

Fluoride release from orthodontic band cements-a comparison of two in vitro models

Objectives. To compare, in vitro, the fluoride release from a conventional glass ionomer cement (Ketac-Cem), a resin-modified glass ionomer cement (3M-Multicure) and a polyacid modified composite (Ultra Band-Lok) using a banded tooth model and a disc model with the same mean cement weight.Methods. Forty pairs of caries-free third molars were collected and divided into two groups, each of 20 teeth. One tooth from each pair was banded with Ketac-Cem and the other with Ultra Band-Lok or 3M-Multicure; the average band size for each cement group was the same. Two coats of nail varnish were painted on each tooth to within 1mm of the band margin. Five discs (4.5mm diameter and 2mm depth) were prepared for each cement, these dimensions having been calculated so that the mean cement weight of the banded tooth model matched that of the disc model for each cement. The fluoride released into 2ml of deionised water, from each banded tooth or disc, was measured at regular intervals over 30 days using an Orion ion-selective electrode connected to an ion analyser.Results. At 30 days, for both banded tooth and disc models, the mean cumulative fluoride release was greatest from 3M-Multicure followed by Ketac-Cem, which in turn released more fluoride than Ultra Band-Lok. These differences were all significant (p<0.05). Despite having the same mean cement weight, the banded tooth model for Ketac-Cem and 3M-Multicure released approximately 3-4 times more cumulative fluoride than the disc model after 30 days (p<001). For Ultra Band-Lok, both models released comparable levels of fluoride (p>0.05).Conclusions. Cement type, specimen geometry and surface area appear to influence significantly fluoride release characteristics.     

Fluoride varnish efficacy in preventing early childhood caries

To determine the efficacy of fluoride varnish (5% NaF, Duraphat, Colgate) added to caregiver counseling to prevent early childhood caries, we conducted a two-year randomized, dental-examiner-masked clinical trial. Initially, 376 caries-free children, from low-income Chinese or Hispanic San Francisco families, were enrolled (mean age +/- standard deviation, 1.8 +/- 0.6 yrs). All families received counseling, and children were randomized to the following groups: no fluoride varnish, fluoride varnish once/year, or fluoride varnish twice/year. An unexpected protocol deviation resulted in some children receiving less active fluoride varnish than assigned. Intent-to-treat analyses showed a fluoride varnish protective effect in caries incidence, p < 0.01. Analyzing the number of actual, active fluoride varnish applications received resulted in a dose-response effect, p < 0.01. Caries incidence was higher for 'counseling only' vs. 'counseling + fluoride varnish assigned once/year' (OR = 2.20, 95% CI 1.19-4.08) and 'twice/year' (OR = 3.77, 95% CI 1.88-7.58). No related adverse events were reported. Fluoride varnish added to caregiver counseling is efficacious in reducing early childhood caries incidence.     

Fluoride varnish may reduce caries in deciduous teeth

J Evid Base Dent Pract 2002;2:96-7     

Fluoride varnish: a primary prevention tool for dental caries

Fluoride varnish is an effective tool that has been proven to prevent dental caries both in primary and permanent dentition. Its ease of use, acceptability and efficacy make it an important tool in the primary prevention of dental caries in high-caries-risk children. There has been an increase in third-party reimbursement for fluoride varnish applications in high-risk children and adults.     

Fluoride and caries prevention: 2. Clinical rationale.

In order to achieve the greatest clinical benefit from the use of fluoride, we must understand its mechanism of action, so that fluoride can be given at the right time, by the best route, at the optimum dosage and in the most suitable form. The first article in this two-part series reviewed the scientific rationale behind the use of fluoride. Part 2 now illustrates fluoride therapy in practical terms, by examining nine clinical cases.