Fluoridated elastomers: in vivo versus in vitro fluoride release

OBJECTIVES: To compare (i) the in vivo release of fluoride from fluoridated elastomers to the in vitro release, and (ii) the residual fluoride content of the elastomers after 1 week in the mouth with and without fluoride toothpaste and mouthrinse. DESIGN: A prospective, longitudinal, cross-over study. Subjects and method: Six subjects were recruited by poster to take part in the study. Each subject had one premolar in each quadrant to which a bracket could be fixed and exemplary oral hygiene. Elastomers were then placed on these brackets. Intervention: The study was divided into two parts: (i) subjects used oral hygiene products with fluoride and (ii) oral hygiene products with fluoride were excluded. Both groups of elastomers were left in the mouth for 1 week. After collection the elastomers were stored in distilled water. MAIN OUTCOME MEASURES: The amount of residual fluoride in the ligatures after they have been placed in the mouth for 1 week was compared with the cumulative fluoride release in vitro over 1 week and 6 months. RESULTS: Only 13 per cent of the total amount of fluoride in fluoridated elastomers was released during the first week in vitro, compared with 90 per cent in vivo. There was a significantly greater amount (P = 0.001) of residual fluoride when the elastomers were in the mouth for 1 week in the presence of fluoride toothpaste and mouthrinse, than when fluoride supplements were excluded. CONCLUSIONS: (1) Higher levels of fluoride are lost from the fluoride elastomers in vivo than in vitro during the first week. (2) A significantly greater amount of residual fluoride was released from the elastomers placed in the mouth when fluoride toothpaste and mouthrinse were used

Fluoride release and uptake abilities of different fissure sealants

Background: The long-term capability of resin sealants and glass ionomer cements to release fluoride is associated to a reduction in pit and fissure caries. The regular use of fluoride varnishes/toothpastes can result in the absorption of fluoride into the sealant. The objective of the present study was to assess the fluoride release/uptake capacities of different fissure sealants. Material and Methods: Three different fissure sealants (Fuji Triage/GC, Fissurit FX/Voco and Grandio Seal/Voco) were examined. Ten discs of each material were prepared. Each disc was incubated with distilled water and then the solution analyzed for diluted for fluoride concentration, using a combination of fluoride electrode (OrionGP 1 S/N 13824, Orion Research Inc, Boston, MA, USA) connected to an expandable ion analyzer (Orion 720A, Orion Research Inc, Boston, MA, USA). Standard curves between 1 and 100 ppm F- were used to calibrate the electrode. Cumulative fluoride release was measured on days 1, 2, 3, 5, 7, 21, 35 and 49, then two different fluoride varnishes/ pastes (Profluorid Varnish/Voco, MI Paste Plus/GC), were applied to the sealants tested, and fluoride release (after reuptake) was measured on days 56, 70 and 84. Results: Kruskal Wallis test confirmed significant differences in fluoride release between Fuji Triage/GC and Fissurit FX/Voco and Grandio Seal/Voco from day 1 ( P < 0.001). The application of fluoride varnish Profluorid Varnish enhanced the fluoride release for all sealants ( P < 0.05). MI Paste Plus enhanced the fluoride release for all sealants except for Fuji Triage/GC ( P > 0.05). Conclusions: The GIC-based sealant (Fuji Triage/GC) released significantly more fluoride than the resin sealants tested. The exposure to the fluoridated varnish (Profluorid Varnish) significantly recharged the sealants tested more than the CPP-ACPF toothpaste (MI Paste Plus)

Fluoride Release from Two High-Viscosity Glass Ionomers after Exposure to Fluoride Slurry and Varnish

The effect of brushing with different fluoride slurries on the fluoride release (FR) of different high-viscosity glass ionomer cements (GICs) was investigated. Fifty-eight discs were fabricated from two high-viscosity GICs (GC Fuji IX (F9) and 3M ESPE Ketac-fil (KF)). Five specimens from each brand were used to measure Vickers microhardness and the remaining were randomly assigned to one of four groups (n = 6) based on two-factor combinations: (1) fluoride concentration in the abrasive slurry (275 or 1250 ppm fluoride as NaF) and (2) immersion in a 22,500 ppm fluoride-containing solution. Specimens were brushed for a total of 20,000 strokes over 4 days with daily FR measurement. Data were analyzed using analysis of variance and Bonferroni tests (α = 0.05). Baseline FR and microhardness values were different between the two tested material brands. Exposure to a 22,500 ppm solution was associated with higher FR but not the exposure to 1250 ppm slurries. Brushing and immersion of glass ionomer cements in a 22,500 ppm F solution led to higher FR that was more sustained for KF. Type of the glass ionomer, progressive brushing, and fluoride varnish affected FR but not the fluoride content in the abrasive slurry

Fluoroacidity evaluation in molten salts

The fluoroacidity of several alkaline fluoride media was studied by monitoring the concentration of electroactive species which is decreasing versus time due to a gas species release, such as silicon fluorides, as indicated by the reaction: SiF(4+x)x- = SiF4(g) + x F- This article relates the Si(IV) reaction study to define a relative fluoroacidity scale by studying the silicon ions stability in different melts. Electrochemical techniques allow the measurement of SiF4+xx- concentration evolution and thus the reaction rate constant to be calculated at different temperatures and for several fluoride media. The article shows that the free F- content depends on the fluoride mixture and that the rate values are correlated with the fluoroacidity allowing a qualitative estimation. Then a fluoride solvents fluoroacidity scale was proposed, scaling the different eutectic melts from basic melt to acidic one: NaF-KF < LiF-KF < NaF-MgF2 < NaF-CaF2 < LiF-NaF < LiF < LiF-CaF2

Fluoride Released From GIC and RMGIC in Saliva and Dentino-Enamel SUbstance

Glass Ionomer Cement (GIC) and Resin Modified Glass Ionomer Cement (RMGIC) are two restorative materials in dentistry that have the capacity of releasing fluoride to saliva, dentino-enamel substance, and the ability to form fluoroapatite crystal. This study aims to compare the amount of fluoride release in saliva and dentino-enamel substance. A total of 48 caries free premolar teeth were prepared to form a cavity with the dimension of 4 x 4 x 2 mm on the buccal surfaces. These teeth were then divided into 3 groups (control, GIC, RMGIC groups). These teeth were then soaked in artificial saliva without fluoride content and were incubated at room temperature (37&nbsp;0C). Each group was divided again into 4 sub groups, with different periods of soaking (1, 3, 10, and 20 days). The fluoride content of saliva was analyzed using ion chromatography. The fluoroapatite on dentino-enamel substance was analyzed using x-ray diffraction or XRD. While there was a significant difference in fluoride release in saliva and no significant difference in fluoroapatite formation on dentino-enamel substance within 3 groups. Fluoride content in saliva showed a significant difference within the 3 groups. No significant difference was found in the fluoroapatite content on dentino-enamel substance

The Fluoride Recharging Capability of Orthodontic Materials: an in-vitro study

Enamel demineralization in the form of white spot lesions (WSLs) around fixed orthodontic appliances is a persistent problem in patients with poor oral hygiene.These lesions can form rapidly within 4 weeks of bracket placement.The purpose of this in-vitro study was to investigate the fluoride recharging capability ofa commercially available orthodontic primer used to minimize the development of WSLs in patients. The three groups tested were: OpalSeal (n=20, Ultradent, South Jordan, UT), ProSeal (n=20, Reliance, Itasca, IL) and Transbond XT (control, n=10, 3M Unitek, Monrovia, CA). The samples(5mmin diameter x 1mm in thickness) weresuspended individually in vials filled with 10mL of deionized water usinga fishing line. The baseline fluoride ion release from all of the samples was measured after two weeks of changing the solution every other day. The samples were then randomly divided into two groups, toothbrush or gel. The samples in the toothbrush group were brushed for one minute every day for 7d, with fluoride containing toothpaste (Colgate-Palmolive Company, New York, NY) and placed in a new solution after each brushing. After 7d of brushing the fluoride ion release was measured. The samples in the gel group were immersed in 10mL of acidulated phosphoric fluoride gel (APF) for one minute, following manufacturer’s instructions, and then placed in a new vial with 10mL of deionized water. At the end of 24hrs fluoride ion release measurementswere made and the samples were placed individually in a new solution. The solution was changed weekly in the gel group over six weeks to simulate the typical length of time between two orthodontic appointments. A final fluoride ion release measurement was taken of all the discs in the gel group 6 weeks after the fluoride gel treatment. The results of repeated-measures analysis indicated that there were no significant differences between the groups at baseline and after 7d of toothbrushing time points. Opal Seal exhibited a significant increase in fluoride uptake (1.0ppm) after 24hrs of fluoride gel exposure but these levels gradually decreasedover 6 weeks (0.04ppm). Pro Seal and Transbond showed no significant fluoride release after the gel or toothpaste applications. The fluoride-containing primer, Opal Seal, had the ability to be recharged with fluoride ions from APF gel. However, the amount of fluoride released from recharged discs decreased gradually over a 6 weeks of time

Effect of layered double hydroxide intercalated with fluoride ions on the physical, biological and release properties of a dental composite resin

OBJECTIVES: The aim of this work was the preparation of a new fluoride-releasing dental material characterized by a release of fluoride relatively constant over time without any initial toxic burst effect. This type of delivery is obtained by a matrix controlled elution and elicits the beneficial effect of a low amount of fluoride on human dental pulp stem cells (hDPSCs) towards mature phenotype. METHODS: The modified hydrotalcite intercalated with fluoride ions (LDH-F), used as filler, was prepared via ion exchange procedure and characterized by X-ray diffraction and FT-IR spectroscopy. The LDH-F inorganic particles (0.7, 5, 10, 20wt.%) were mixed with a photo-activated Bis-GMA/TEGDMA (45/55wt/wt) matrix and novel visible-light cured composites were prepared. The dynamic thermo-mechanical properties were determined by dynamic mechanical analyzer. The release of fluoride ions in physiological solution was determined using a ionometer. Total DNA content was measured by a PicoGreen dsDNA quantification kit to assess the proliferation rate of hDPSCs. Alkaline phosphatase activity (ALP) was measured in presence of fluoride resins. RESULTS: Incorporation of even small mass fractions (e.g. 0.7 and 5wt.%) of the fluoride LDH in Bis-GMA/TEGDMA dental resin significantly improved the mechanical properties of the pristine resin, in particular at 37°C. The observed reinforcement increases on increasing the filler concentration. The release of fluoride ions resulted very slow, lasting months. ALP activity gradually increased for 28 days in hDPSCs cell grown, demonstrating that low concentrations of fluoride contributed to the cell differentiation. CONCLUSIONS: The prepared composites containing different amount of hydrotalcite filler showed improved mechanical properties, slow fluoride release and promoted hDPSCs cell proliferation and cell differentiation

THE EFFECT OF NANO-FILLED RESIN COATING ON FLUORIDE RELEASE IN A NEW CONVENTIONAL GLASS IONOMER CEMENT

poster abstractThe objective of this study was to evaluate fluoride release amounts and patterns from high strength tooth filling material (EQUIA™) which is a con-ventional Glass Ionomer Cement, and investigate whether the application of nano-filled resin-based coating with different thicknesses has any effect on fluoride release from this new material. A total of 120 disc shaped specimens (10 x 2 mm) of EQUIA™ were fabricated according to manufacturer’s in-structions. Samples were subsequently divided into three groups: no resin coating; coated with nano-filled resin-based coat; coated with nano-filled resin-based coat then subjected to abrasion using a mechanical tooth brush-ing machine. Each specimen was soaked individually into a polyethylene container with 20 ml of distilled water and stored at 37ºC. Samples from each group were soaked for four time points; 1 day, 7 days, 14 days and 21 days. Fluoride content was then measured using a fluoride-specific ion elec-trode (Model 9609BNWP, Orion Research, Boston MA, USA). The effects of time and coating on fluoride release were analyzed using two-way analysis of variance (ANOVA), with multiple comparisons performed using the Sidak method at an overall 5% significance level. The distribution of the fluoride release measurements was examined and a natural logarithm transformation of the data was necessary to satisfy the ANOVA assumptions. The time-by-coating interaction was significant (p<0.0001). We can conclude that fluo-ride level significantly increased with time for non-coated and coated then abraded samples only. Application of resin coat significantly reduced fluoride release. Also, subjecting coated samples to tooth brush abrasion increased the fluoride release when compared to coated specimens but was still signifi-cantly less than uncoated samples

Fluoride Release from Fluoride Varnishes under Acidic Conditions

Objective: The aim was to investigate the in vitro fluoride release from fluoride varnishes under acidic conditions. Study design: Poly(methyl methacrylate) blocks (Perspex, n=3 per group) were painted with 80±5 mg fluoride varnish (n=10) and placed into artificial saliva for 30min. Then, blocks were placed into either 1% citric acid (pH 2.27) or 0.3% citric acid (pH 3.75) solutions (n=3 per solution and varnish) for 30min with the solutions being replaced every 5min. Saliva and acid solutions were analyzed for fluoride content. Data were analyzed using three-way ANOVA (varnish, solution, time). Results: The three-way interaction was significant (p>0.0001). Fluoride release and release patterns varied considerably between varnishes. Fluoride release in saliva varied by a factor of more than 10 between varnishes. Some varnishes (CavityShield, Nupro, ProFluorid, Vanish) showed higher fluoride release in saliva than during the first 5min of acid exposure, whereas other varnishes (Acclean, Enamel-Pro, MI Varnish, Vella) showed the opposite behavior. There was little difference between acidic solutions. Conclusions: Fluoride release from fluoride varnishes varies considerably and also depends on the dissolution medium. Bearing in mind the limitations of laboratory research, the consumption of acidic drinks after fluoride varnish application should be avoided to optimize the benefit/risk ratio

A comparative study of fluoride release from two different sealants

Objectives: The introduction of fluoride releasing sealants and glass ionomer cements as fissure sealants adds another dimension to prevention of pit and fissure caries. The ability of resin sealants and glass ionomer cements to release fluoride on a long term basis to the sealed enamel and the adjacent unsealed pit and fissure and cuspal in - cline enamel may allow for further reduction in pit and fissure caries experience for children. Hence, the study was conducted to compare the amount of fluoride release in the plaque after placing fluoride releasing pit and fissure sealants and glass ionomer fissure sealants used in Atraumatic Restorative Treatment (ART) approach. To compare the fluoride release of both the materials at the different time intervals. Material and Methods: A total of 60 school going children were included in this study. Before application of the sealants, baseline plaque fluoride levels were estimated from all the study subjects. After application of sealants again the same was estimated at an interval of 24 hour, 9 days, 2 weeks and 4 weeks. Results: The peak plaque fluoride levels were achieved at 24 hours after application of fissure sealants in all the groups. Conclusions: Within the limitation of the study, the present study indicated that fluoride releasing fissure sealants may act as a source of fluoride in plaque which will help in preventing pit and fissure and smooth surface caries in the tooth sealed with fissure sealants