Fluoride release and uptake by glass ionomers

Abstract – The aim was to study the fluoride release 1) from 7 and 15-month-old glass ionomer specimens after treating them with fluoride; 2) from fresh compared with matured material; and 3) from specimens stored for 29 months in running water. Glass ionomer test specimens which had been in running water for first 7 then 15 months were treated with a 50 ppm fluoride solution after which the specimens were again exposed to running water for first 24 h and then 1 wk. The fluoride release was measured after each of the two periods of time. The fluoride treated specimens released more fluoride than the nontreated ones. This effect was not observed with composite resin specimens which were studied for comparison. Fluoride release from fresh glass ionomer specimens was observed to be 3–10 fold compared to specimens that had matured for 3 days. The release of fluoride from specimens that had been in running water for 29 months was measured and the results were compared with those of earlier measurements. It was found that the release reached a constant level for all tested glass ionomers during the second year.     

Fluoride release in vitro from various glass ionomer cements and resin composites after exposure to NaF solutions

The release of fluoride from 1) discs made from five glass ionomer cements and two composites, and 2) the same discs after exposure to different NaF solutions, were studied. The specimens were placed in distilled water for 10 wk. After 24 h and then once a week, the specimens were transferred to fresh distilled water. After 5 wk, the specimens were divided into four groups and exposed to 0, 0.02, 0.2 and 2% NaF solutions for 5 min. The fluoride release was highest during the first week after preparation, after which it decreased sharply and then more slowly. The amount of fluoride released was ordered: liner/base>restorative glass ionomer>composites. The composites released significantly less fluoride than the glass ionomer cements. After exposure to NaF, the fluoride release was significantly higher for the silver cermet material than for the other glass ionomers tested. From a clinical point of view, the results from this study imply that glass ionomer restorations may act as intraoral devices for the controlled slow release of fluoride at sites at risk for recurrent caries.     

Short- and long-term fluoride release from glass ionomer based liners.

The aim of the study was to measure the fluoride release from glass ionomer based liners/bases after storing the specimens for 24 h and for 6 months in running water. The fluoride release was greater in the beginning than after half a year. From most liner materials the initial and the long-term release was greater than from the glass ionomer filling material studied for comparison. From two liners the release was minimal, just at the detection limit.     

Short- and long-term fluoride release from glass ionomer based liners

Abstract— The aim of the study was to measure the fluoride release from glass ionomer based liners/bases after storing the specimens for 24 h and for 6 months in running water. The fluoride release was greater in the beginning than after half a year. From most liner materials the initial and the long-term release was greater than from the glass ionomer filling material studied for comparison. From two liners the release was minimal, just at the detection limit.     

Short- and long-term fluoride release from glass ionomers and other fluoride-containing filling materials in vitro

Abstract – Test specimens of seven different glass ionomer filling materials and one fissure sealant were exposed to running water for 2 yr. One amalgam and one composite, both containing fluoride, were included for comparison. The fluoride release from the specimens was measured periodically after storing the specimens for 24 h or 1 wk in a small amount of water. The fluoride release From the glass ionomers decreased with time and a constant level was reached for most products during the 2-yr period. The release was increased by lowering the _pH of the storage solution. The release from the glass ionomers was clearly greater than from the amalgam and the composite.     

Short- and long-term fluoride release from glass ionomers and other fluoride-containing filling materials in vitro

Test specimens of seven different glass ionomer filling materials and one fissure sealant were exposed to running water for 2 yr. One amalgam and one composite, both containing fluoride, were included for comparison. The fluoride release from the specimens was measured periodically after storing the specimens for 24 h or 1 wk in a small amount of water. The fluoride release from the glass ionomers decreased with time and a constant level was reached for most products during the 2-yr period. The release was increased by lowering the pH of the storage solution. The release from the glass ionomers was clearly greater than from the amalgam and the composite.     

Fluoride release from glass ionomer cement in vivo and in vitro

The aims of this study were to investigate in vivo the release of fluoride from three glass ionomer cements (GICs) Vitrebond, Ketac-Fil and ChemFil II into the saliva of preschool children for a 1-year period and also to study in vitro the release-absorption-release of fluoride from the same GICs for 16 weeks. In the first part of the study, glass ionomer restorations were placed in primary teeth in preschool children. Unstimulated saliva was collected and the fluoride in the saliva was measured before placement of the restorations, immediately after, after 3 weeks, after 6 weeks, and after 1 year. In the second part of the study, test specimens of GICs were placed in deionized water and the release of fluoride was measured weekly for 16 weeks. At week 12, samples were exposed to fluoride toothpaste. The concentration of fluoride in saliva was 0.04 ppm before placement of the restorations. After three weeks it had increased to 0.8 ppm and the level remained as high as 0.3 ppm even after 1 year. In the laboratory study the tested glass ionomer cements showed a capacity to absorb fluoride from the fluoride toothpaste and then release it. It is concluded that glass ionomer cement can act as a rechargeable slow release fluoride device.     

Effect of encapsulation on the fluoride release from conventional glass ionomers.

OBJECTIVES: The aim of the present study is to investigate the effect of the type of encapsulation and the batch on the fluoride release of conventionally setting glass ionomer cements Ketac-Fil and Fuji Cap II. METHODS: Three capsule types were selected: the capsules of Ketac-Fil and Fuji Cap II, and standard capsules. Six individual series of five cylindrical specimens were made from fresh mixes and leached at 37 degrees C with 25 ml distilled water up to 56 days. A second series of five specimens per formulation in original capsules was made from fresh mixes of another batch. The fluoride concentration was determined by means of a fluoride-ion selective electrode. RESULTS: The fluoride release profiles of a given glass ionomer formulation generally run parallel regardless of the type of encapsulation. When the amounts of fluoride released within the specific formulation were compared as a function of the capsule type, statistically significant differences were only found for Ketac-Fil. Comparing the amounts of fluoride released by different batches of a given glass ionomer formulation, statistically significant differences were only found for Fuji Cap II. SIGNIFICANCE: The type of encapsulation may affect the fluoride release of a given glass ionomer formulation quantitatively, but not qualitatively. Apparently, different batches of the same formulation may result in different amounts of fluoride released.     

Inhibitory effect on S. mutans by fluoride-treated conventional and resin-reinforced glass ionomer cements

The aim of the present study was to study the effect of fluoride gel treatment on fluoride release and inhibition of acid production of Streptococcus mutans by different glass ionomer cements. Test slabs of four glass ionomer materials were fitted into the bottom of a test tube. A layer of S. mutans cells was centrifuged onto the test slabs, and the specimens were incubated for 4 h in 1.7% sucrose solution. Incubations were made using fresh, aged (29 d), aged and F-treated (1.25% F-gel), and aged, F-treated and aged samples ( n = 15 per group). After each incubation, pH and F contents of the fluid phase were determined. The freshly mixed glass ionomer samples released large amounts of fluoride, and the pH fall in the fluid phase was significantly inhibited. For aged samples, the fluoride release decreased strongly and no inhibitory effect on acid production by S. mutans was seen. After application of fluoride gel, fluoride release and inhibitory effect were significantly higher than initially for all glass ionomer cements. In conclusion, all glass ionomer cements were able to take up fluoride and subsequently release it, which resulted in reestablishment of their antibacterial effect. The patterns of fluoride release and antibacterial action were virtually the same for conventional and resin-reinforced glass ionomer cements.     

四种玻璃离子充填材料释氟性与溶解性的研究

目的 比较4种玻璃离子充填材料短期内氟离子释放能力和溶解性,为临床选择充填材料提供依据.方法 实验选取1种传统型玻璃离子水门汀(SC),2种高强度玻璃离子水门汀FujiⅨ(F9)和Ketac Moler(KM),1种树脂改良型玻璃离子水门汀FujiIILC (F2LC),和1种复合树脂Z100( CR,3M)共5种材...     

An in vitro study of fluoride release from a resin-modified glass ionomer cement after exposure to toothpaste slurries of different pH

. The aim of the study was to evaluate the fluoride release from an aged resin-modified glass ionomer (Vitremer) after exposure to five toothpaste slurries with different pH values. Cylindrical specimens of the material were leached in de-ionized water for 3 months and then exposed for 30 min daily for 10 days to three dentifrice slurries (20 specimens/group) containing 0.05% fluoride with pH values of 2.6, 5.7 and 8.3 and two non-fluoridated slurries with pH values of 2.5 and 5.7. A neutral NaF solution (0.05% F) was used as a control. During the 30 min exposure time, the fluoride concentration was gradually decreased in order to imitate the clinical situation. Thereafter, specimens were immersed individually in de-ionized water and the fluoride release determined. After the first day of exposure, all groups except one without fluoride (pH 5.7) showed significantly (P<0.05) increased fluoride release. After exposure to the fluoridated toothpaste slurry with pH 5.7, significantly (P<0.05) more fluoride was released compared to the toothpaste slurry with pH 8.3. Low pH (2.5 or 2.6) of the slurry resulted in a significantly (P<0.05) higher fluoride release, regardless of whether it was fluoridated or not. The total amount of fluoride released after exposure to the more acidic fluoride toothpaste slurry was greater than that released from the more acidic non-fluoride toothpaste and the less acidic fluoride toothpaste. Our data indicate that the fluoride release from the resin-modified glass ionomer studied may be in-creased after treament with an acidified NaF-toothpaste. Received: 24 January 2000 / Accepted: 20 July 2000     

Effects of temperature on the fluoride release and recharging ability of glass ionomers

This study investigated the effects of environmental temperature on the fluoride release and recharging ability of glass ionomers. Five disk specimens (15 mm in diameter and 1 mm thick) were made of each of the following materials: a conventional luting glass ionomer, two high viscosity restorative glass ionomers and a restorative resin-modified glass ionomer. The fluoride release of each material was measured at 4 degrees C, 37 degrees C and 55 degrees C. An additional three groups, which were made of the same materials, were stored in distilled and deionized water for 30 days and recharged in 250 ppm fluoride solution at 4 degrees C, 37 degrees C and 55 degrees C for five minutes. The fluoride re-release was measured daily from two days prior to two days after the recharging process. At all temperatures, the luting glass ionomers showed the greatest fluoride release and recharging ability, followed by the resin-modified glass ionomer, then the high viscosity glass ionomers. For each material, the fluoride release increased with increasing temperature and all glass ionomers showed greater recharging ability at higher temperatures. An increase in environmental temperature increased both the fluoride release and recharging of the glass ionomers. This may be important in developing regimes for improving the delivery of topical fluoride products.     

Fluoride release and uptake by aged resin-modified glass ionomers and a polyacid-modified resin composite

Little has been reported of the relationship of fluoride release and weight loss, and the effects of use of different fluoride agents on restorations, for the new generation of glass ionomer cements. The objectives of this study were to compare fluoride release of fresh and aged specimens of a polyacid-modified resin composite (Dyract), and of three resin-modified glass ionomer cements (Fuji II LC, Photac-Fil, Vitremer); and to correlate fluoride release and weight loss of aged specimens after recharging with three different fluoride agents. All materials showed high initial fluoride release immediately after uptake when using the agents. However, the levels of fluoride release dropped rapidly soon afterwards. Although initial fluoride release was significantly different between Dyract and the three resin-modified glass ionomers, when different fluoride agents were used on aged specimens after recharging, no significant differences were found after the first few hours. Linear regression analyses also showed no correlation between cumulative fluoride release and weight loss. Possible beneficial oral health effects may only be expected by frequent exposure of these materials to fluoride agents.     

Fluoride release from orthodontic adhesives

Two commercial orthodontic adhesives containing fluoride were evaluated in vitro for fluoride release. Fluoride release is critical in preventing both decalcification around orthodontic brackets and the formation of white spot lesions. A paste-type adhesive composite resin and a glass ionomer luting agent were compared to a glass ionomer restorative material to determine fluoride release. The composite resin adhesive released minimal fluoride for only three days and then ceased. The glass ionomer adhesive released fluoride at a similar rate to the glass ionomer restorative material with fluoride release still evident at three months.     

Fluoride release from a fluoride-containing amalgam, a glass ionomer cement and a silicate cement in artificial saliva

This study aimed to compare the fluoride release from a flouride-containing amalgam, a silicate cement and a glass ionomer cement in artificial saliva. After storing specimens in an artificial saliva for 7 weeks, the fluoride content in the solvent was measured by a spectrophotometric method. The fluoride release from silicate cement was about 5 times greater than from glass ionomer cement, which again showed a release 4 times greater than the fluoride-containing amalgam. The fluoride release relative to fluoride content in test specimens was greater from fluoride-containing amalgam and silicate cement than from glass ionomer cement.     

Long-term fluoride release from a glass ionomer cement,a compomer,and from experimental resin composites

The aqueous phase of glass ionomer cements enables fluoride ions to diffuse and to be released from the material. The matrix of resin composites is much less hydrophilic, and fluoride incorporated in the material is only released in small amounts. It was the purpose of the present work to study the influence of resin matrix formulation on the fluoride release from experimental, fluoride-containing resin composites. The resin composites were based on methacrylate monomers and the adduct of maleic anhydride and HEMA (2-hydroxyethyl methacrylate). The resin composites contained 1 w% or 5 w% of AlF3*3H2O. A glass ionomer cement and a compomer were used as controls. Five disks of each material were stored in distilled water at room temperature. By means of a fluoride sensitive electrode, the fluoride release from disk-shaped specimens was determined periodically over 3 years. The glass ionomer cement released the most fluoride (1.54 +/- 4 microg/cm2 after 1 year and 248 +/- 7 microg/cm2 after 3 years). The compomer released relatively little fluoride during the 1st year (30 +/- 1 microg/cm2) but after this time the rate of fluoride release became equal to that of the glass ionomer cement, resulting in a release of 122 +/- 8 microg/cm2 after 3 years. Regarding the resin composites, the fluoride release increased with the hydrophilicity and the acid character of the polymer matrix. The release, however, was significantly lower than that from the glass ionomer cement and the compomer and ranged from 1.2 +/- 0.07 to 42 +/- 3.9 microg/cm2 at 1 year and from 2.3 +/- 0.16 to 79 +/- 6 microg/cm2 at 3 years.     

An ex vivo investigation into the fluoride release and absorption profiles of three orthodontic adhesives.

Prevention of peri-bracket decalcification is essentially mediated by effective oral hygiene, which is patient dependent. The potential to compensate for poor oral hygiene may be through the release of free fluoride ions from direct bonding agents. It is well established that glass ionomer cements (GICs) release free fluoride ions which may be replenished by exposure to fluoride containing solutions. The aim of this ex vivo study was to compare the fluoride release and absorption profiles of a recently developed low fusion, monophase GIC, Limerick glass, with two materials in common clinical use, namely, Fuji-Ortho L.C. and Concise. Ten test specimens of each material were fabricated and stored in deionized water at 37 degrees C. The concentration of fluoride release was measured daily for the first 7 days after immersion and then weekly for 5 weeks. On day 42 the test specimens were recharged in 2 per cent sodium fluoride solution and fluoride release was measured initially after 24 hours and then every 48 hours. The recharge regimen was repeated for 3 weeks. Both Limerick glass and Fuji-Ortho L.C. demonstrated the characteristic fluoride release pattern of GIC with a rapid elution of fluoride after the first 24 hours followed by a more gradual release profile over the following 2 weeks. Fuji-Ortho L.C. released the greatest quantity of fluoride but the release profile of Limerick glass was more sustained. Concise released negligible amounts of fluoride. Limerick glass and Fuji-Ortho L.C. showed an increase (P < 0.01) in fluoride release following exposure to 2 per cent sodium fluoride that decreased both with time and subsequent exposures to fluoride supplement.     

Fluoride release from a glass ionomer cement

abstract – The release of fluoride from a glass ionomer cement (ASPA®) was. compared with that from a silicate cement. Test specimens were shaken in a solution with hydroxyapadte for 7 weeks. The solution was changed every week and the fluoride taken up by the hydroxyapatite measured. The specimens released considerably more fluoride during each of the first 2 weeks than during each of the subsequent 5 weeks. The continued release did not decrease very much with time. Slightly more fluoride was released from the glass ionomer cement than from the silicate.     

Surface roughness and weight loss of esthetic restorative materials related to fluoride release and uptake.

The objective of this study was to assess the surface roughness of eight esthetic restorative materials and the relationship with weight changes during fluoride release and uptake. Five specimens each of ChemFil Superior, Fuji IX Dyract, Fuji II LC, Vitremer, Photac-Fil, Ketac-Silver, and Z100 (control) were prepared and immersed in 2 ml of artificial saliva at 37 degrees C. The changes in specimen weight and fluoride release were monitored for 12 weeks. This protocol was repeated after recharging the specimens with 1.23% APF gel for 12 more weeks. The immersed and fresh specimens for each material were then examined with SEM and surface profilometry. There was a significant weight loss for all glass ionomer cements following APF gel application (P < 0.01), which correlated with fluoride release (r = 0.89-0.98). Mean roughness (Ra) measurements and SEM showed that roughness increased from the resin composite to the conventional glass ionomer cements. The marked erosive effect of APF gel on glass ionomer restorations could increase surface colonization by plaque micro-organisms, and reduce the longevity of the restorations.     

Fluoride release from a glass ionomer cement.

The release of fluoride from a glass ionomer cement (ASPA) was compared with that from a silicate cement. Test specimens were shaken in a solution with hydroxyapatite for 7 weeks. The solution was changed every week and the fluoride taken up by the hydroxyapatite measured. The specimens released considerably more fluoride during each of the first 2 weeks than during each of the subsequent 5 weeks. The continued release did not decrease very much with time. Slightly more fluoride was released from the glass ionomer cement than from the silicate.