Fluoride-releasing Composites Research Articles

Estimation of fluoride release and recharge potential among Zirconomer, GC Gold Label Hybrid, Ketac Molar, and Tetric Prime: An in vitro study

Abstract Background: The preventive role of fluoride in caries control is mainly due to the formation of fluorapatite crystals which are more resistant to acid attack. Glass ionomer cement (GIC), its newer modifications, and certain composites in which fluoride has been incorporated show fluoride release. Aim: This research aims to compare the initial fluoride liberated, the fluoride liberated after recharge, and the mean percentage reduction of modified varieties of GICs along with fluoride-releasing composites. Materials and Methods: Forty specimen blocks of the materials to be tested were divided into 5 groups (n = 8), namely Group 1: Zirconomer (SHOFU), Group 2: GC GOLD Label Hybrid (GC), Group 3: Tetric Prime (Ivoclar), Group 4: Ketac Molar (3M), and Group 5: TE-Econom Plus (Ivoclar). The initial fluoride liberated was measured on the 1st day, after 1 week, and after a fortnight, using a benchtop analyzer and total ionic strength adjustment buffer III analyzer. Then, fluoride application was done with fluoridated dentifrice using the hand brush method, and the samples were rechecked for fluoride release at similar time intervals, i.e. 1, 7, and 15 days. Results: Zirconomer showed significantly higher initial fluoride release. The minimum mass of fluoride was released by TE-Econom. A similar pattern was observed for fluoride liberation after recharge, with Zirconomer showing maximum re-release of fluoride and TE Econom showing maximum reduction in fluoride release after 15 days. Conclusion: Zirconomer exhibited high initial fluoride liberation and fluoride liberation after recharge following topical fluoride application. GC Gold Label Hybrid and Ketac Molar showed the least percentage reduction in the biweekly fluoride liberation which was remarkably lower than Zirconomer. Fluoride-releasing composites showed the least amount of initial fluoride liberation and fluoride liberation after recharge.

A Scanning Electron Microscope Evaluation of the Efficacy of Different Fluoride-releasing Dental Restorative Materials to Prevent Enamel Demineralization: An In Vitro Study

Aim of the present research was to investigate the effectiveness of various fluoride-releasing dental restorative agents in preventing demineralization of enamel. Eighty human mandibular permanent molar teeth constituted the study group. All samples were subjected to storage in thymol, after which they were taken out to prepare alike proximal box in each. Inductions of artificial enamel surface lesions were done by placing the teeth in demineralizing solution for 96 hours. Subsequently, all 80 molars were randomly assigned to any of the four groups (i.e., 20 in every individual group) according to the restoration as group A: giomer (composite resin containing surface pre-reacted glass-ionomer fillers), group B: compomer (polyacid-modified composite resin), group C: resin-modified glass-ionomer cement (RMGIC), group D: fluoride-releasing composite. After this, the pH cycling was performed, and the samples were subjected to examination beneath scanning electron microscope (SEM). Higher mean areas of remineralization were noted when RMGIC (96.34 ± 0.06) was used followed by the compomer (109.52 ± 0.17), giomer (118.39 ± 0.82), and the fluoride-releasing composite group (129.27 ± 0.31) in that order. A statistically significant difference was seen amid the investigational groups that utilized different restorative agents (p <0.001). A pairwise evaluation that was performed revealed that except for the giomer group and the compomer group, a statistically significant difference (p <0.001) was found among the experimental groups. This research infers that the RMGIC-treated samples exhibited significantly superior performance in preventing enamel demineralization in comparison to compomer, giomer as well as fluoride-releasing composites. One among the highly frequently employed anticariogenic materials is fluorides. Owing to this characteristic, they are integrated into numerous restorative substances. Nevertheless, the quantity and speed of fluoride release differ in different agents, which translates to the efficacy of the restorative agent in avoiding demineralization about the restoration.

Effect of Adhesion Booster on Fluoride-releasing Composite: An in vitro Study

Objective: To evaluate the shear bond strength of stainless steel brackets bonded with fluoride-releasing composite resins, comparing effect of adhesion booster and conventional primer.Materials &amp; Method: Sixty extracted premolars were subjected to bracket bonding with fluoride-releasing composite resin; which were bonded by randomly divided into two groups of bonding agents: Group 1- conventional primer as control group, Group 2- adhesion booster. After bonding, the samples were thermocycled (500 cycles) at 5ºC and 55ºC temperatures. After 48 hours they were subjected to shear bond strength testing in occluso-gingival direction, using an MTS 810 Universal Testing Machine with load speed of 0.5 mm/min.Result: Mean shear bond strength was significantly more in samples bonded with adhesion booster (14.792±3.805 Mpa) as compared to conventional primers (11.327±4.047 Mpa). There was statistically significant difference in shear bond strength between the groups (p=0.001).Conclusion: The use of the adhesion booster significantly increased the bond strength of bracket bonded with fluoride-releasing composite.

Ion migration from fluoride-releasing dental restorative materials into dental hard tissues

This study was carried out in order to determine the extent to which ions released from fluoride-containing dental restoratives migrated through the enamel and dentine of extracted teeth. A total of 40 permanent human 3rd molars were used. They were extracted for orthodontic reasons, and employed within 1month of extraction. A cervical (Class V) cavity was prepared in each tooth, then filled with one of: a conventional glass-ionomer, a resin-modified glass-ionomer, a polyacid-modified composite resin ("compomer") or a fluoride-releasing resin composite. Ten samples were prepared per material. After 1month, five specimens per material were prepared and examined under SEM/EDX. Concentrations of sodium, aluminium, strontium, fluorine, magnesium, silicon, phosphorus and calcium were determined within the tooth. After 18months, the remaining five specimens for each material were prepared and studied in the same way. The greatest extent of ion migration into the tooth was found with the conventional glass-ionomer and least migration was found for the fluoride-releasing composite, which showed no evidence of fluoride migration at all. Levels of migrating ions were generally higher in the 18month specimens than in the 1month specimens, and also higher in the dentine than in the enamel. Ions released by restorative dental materials have been shown conclusively for the first time to be capable of migrating into the enamel and dentine surrounding the restoration. The conventional glass-ionomer showed the highest level of ion migration whereas the fluoridated composite resin showed little if any ion migration. This suggests that the conventional glass-ionomer has the greatest caries inhibiting effects of all the materials tested, and the fluoridated composite the least.

Effects of periodic fluoride treatment on fluoride ion release from fresh orthodontic adhesives

ObjectivePeriodic fluoride treatment may contribute to the ability of fresh orthodontic adhesives to provide long-term F− release. The effects of periodic fluoride treatment on the amount of F− release from fresh orthodontic adhesives was investigated. MethodsF− release was measured from a nonfluoride-releasing composite, a fluoride-releasing composite, a polyacid-modified composite (compomer), and two resin-modified glass-ionomer cements (RMGICs) at 1, 2, and 5 days after one of the following treatments: 225ppm F− solution, 900ppm F− solution, acidulated phosphate fluoride gel (APF), fluoridated dentifrice, and deionised water (control). F− release was measured in a 5-day cycle, which was repeated 9 consecutive times. The amount of F− release for each group was analysed using the repeated measures analysis of variance. Statistical significance was set at a level of α=0.05. ResultsPeriodic fluoride treatment temporarily increased F− release in fresh fluoride-releasing orthodontic adhesives, but not in fresh nonfluoride-releasing composite. The order of effective fluoride-release was RMGICs>compomer>fluoride-releasing composite>nonfluoride-releasing composite. The application of APF or 900ppm F− solution was the most effective way to maintain F− release from fresh orthodontic adhesives. However, the amount of F− release gradually decreased with increasing specimen age. ConclusionGiven the difficulty of routine use of APF at home, the results of this study show that a combination of RMGICs and high-dose fluoride mouth rinse is the most effective protocol to maintain F− release from fresh orthodontic adhesives. Clinical significanceMost studies have investigated fluoride-uptake abilities using aged materials in which fluoride had been lost for at least 1 month. This study has found that periodic fluoride treatment altered the conventional F− release pattern of fresh fluoride-releasing materials and type of fluoride-containing medium plays a more critical role in fluoride recharging of the materials than fluoride concentration. This study will help clinicians to find the most effective fluoride treatment protocol of fresh materials.

Effects of different fluoride recharging protocols on fluoride ion release from various orthodontic adhesives

ObjectiveThe purpose of this study was to find the most effective fluoride recharging protocol for orthodontic adhesives. MethodsFive orthodontic adhesives were used: a non-fluoride-releasing composite, a fluoride-releasing composite, a polyacid-modified composite (compomer), and two resin-modified glass-ionomer cements (RMGICs). Each specimen was placed into deionized water (DW) and the initial fluoride ion release was measured for 2 months. Each specimen was then subjected to four different treatments to simulate a fluoride recharge: 1000ppm NaF solution, acidulated phosphate fluoride gel (APF), fluoride-containing dentifrice and DW (control). After topical fluoride treatment, each specimen was submitted to fluoride re-release tests. ResultsFluoride-containing adhesives initially showed higher rates of fluoride ion release, but significantly declined to lower levels. The overall cumulative fluoride ion release during the initial period was RMGICs>compomer>fluoride-containing composite>non-fluoride-releasing composite. After topical fluoride treatment, the amount of fluoride ion re-released was proportional to the amount of fluoride ion previously released from the adhesives. However, the amount of fluoride ions released only lasted for 2 days and then returned to the levels before fluoride application. The overall cumulative fluoride ion re-release according to the fluoride treatments was APF and NaF solution>dentifrice. ConclusionThis study suggests that using the combination of RMGICs and a fluoride-containing mouth rinse solution is the most effective protocol for long-term fluoride re-release from orthodontic adhesives, given the difficulty of routine use of APF at home, although all topical fluoride treatments can recharge fluoride ion in adhesives.

Materiais Restauradores Libertadores de Flúor

The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression. Fluoride-containing dental materials reported in literature are glass-ionomer cements, resin-modified glass-ionomer cements, polyacid-modified composites (“compomers”), fluoride-releasing composites and fluoride-releasing amalgams. Therefore, original scientific papers and reviews listed in PubMed were included in the review. Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries. Fluoride-releasing materials, predominantly glassionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of restorative materials.

Formulation and characterization of a novel fluoride-releasing dental composite

Objectives The aims of this study were to formulate a novel fluoride-releasing dental composite and to evaluate its mechanical properties, fluoride release and recharge capabilities, water sorption and solubility. Methods A fluoride-releasing dimethacrylate monomer containing a ternary zirconium fluoride chelate was synthesized. Three experimental fluoride-releasing composites were fabricated with different monomer formulas (wt.%)—(1) Control A: 40 BisGMA/40 TEDMA/20 UEDMA; (2) Experimental: 20 F-releasing monomer/20 BisGMA/40 TEDMA/20 UEDMA; (3) Control B: the same formula as Control A except that it contained 10 wt.% (of total monomer) tetrabutylammonium fluoride (TBAF), which had a fluoride content equivalent to Experimental. All three materials had the same filler content: 55 wt.% silanized fluoroaluminosilicate particles (0.8 μm) and 10 wt.% silanized fumed silica (14 nm). All materials contained 0.17 wt.% camphorquinone (CQ) as a photoinitiator and 0.69 wt.% ethyl-4-dimethylaminobenzoate (4EDMAB) as an accelerator. The materials were tested for fluoride release (for 184 days), fluoride recharge, compressive and flexure strength, water sorption and solubility. The data were analyzed using ANOVA and Tukey-HSD tests, and Kruskal–Wallis test. Results The experimental composite had significantly higher fluoride release and fluoride recharge capabilities than both Control composites. It had significantly better physical and mechanical properties than Control B. Significance The combined use of the fluoride-releasing dimethacrylate monomer and fluoride-releasing filler can provide sustained high fluoride release and recharge as well as acceptable mechanical and physical properties. Simply adding organic fluoride salt in the monomer yields composites with poor mechanical and physical properties.

Surface Changes of Fluoride-Releasing Composites: a Comparison of in Vivo and in Vitro Results

Fluoride-releasing composites lose fluoride very slowly over time. An interesting question is the possible change in mechanical properties related to the F release. If this happens, it might be expected that the mechanical properties of the outer surface of a fluoridating composite are affected first. The purpose of this study was to investigate in vivo and in vitro the changes in surface microhardness and surface structure of three fluoride-releasing composites and a non-F-containing control after 28 days. In the in vitro experiment, the composites were stored in tap water at 37°C. The results show that all composites stored in water were significantly softened after 28 days. In vivo, however, a very different picture emerged: The surface microhardness of the fluoride-releasing composites did not change significantly. In vitro, the data indicate that the amount of softening of the fluoridating composites is related to the amount of fluoride released. No relation was found between the amount of F released in one month in vitro and the microhardness changes in vivo. SEM micrographs of fluoridating composites do not reflect the microhardness changes mentioned.

Review of Fluoride Release and Secondary Caries Reduction by Fluoridating Composites

Secondary caries is one of the main reasons to replace restorations. Due to the pressure to eliminate or reduce the number of amalgam restorations in many countries, fluoride-releasing composites have gained in importance. This review limits itself to information relevant to secondary caries near fluoride-releasing anterior or posterior composites. Although many parameters are very important in composite functioning, a weak spot near a filling is always the interface and the locally present interfacial gap between the composite and the hard tissues, where secondary caries takes place due to plaque action. Relevant parameters such as the amount of fluoride released in vitro in μg.cm-2, the rate of fluoride release, and the period of fluoride release are compared for several composites. In vitro F release has been measured for some fluoridating composites for more than five years. Unfortunately, F release in vivo or in situ cannot be measured adequately. The fluoride released by the composites considered is partly taken up by the surrounding tissues, partly released to the saliva, and partly efficacious in possible marginal gaps and defects. A major part of this paper pertains to in vitro, in situ, and in vivo secondary caries reduction experiments. In vitro caries reductions in the order of 40% from F-releasing composites vs. controls have been found. In in situ model investigations under plaque and saliva conditions, secondary caries reduction percentages of between 40 and 50% have been experimentally measured in gaps in enamel near F composites.

The Influence of Fluoride-releasing Bonding Composites in the Development of Artificial White Spot Lesions. An Ex Vivo Study

This study investigates the effects of fluoride-releasing bonding composites on the development of artificially created white spot lesions ex vivo. The severity of the lesions was estimated visually using the von der Fehr Caries Index. The integrated mineral loss of the lesions (delta z) was measured using microradiography/microdensitometry. The results of the visual assessment indicated that teeth bonded with Reliance exhibited more Grade 2 lesions than expected. Teeth bonded with Mirage Dual Cure, however, showed a high prevalence of teeth with no lesions (Grade 0) and few with Grade 2. Microdensitometric analysis found 17 subsurface lesions; 14 of these were in the non-fluoridated groups (Right-On and Heliosit), and 3 and 1 in the fluoridated groups (Reliance and Mirage Dual Cure), respectively. Lesion mineral content ranged from 64.93 to 20.43 per cent for Right-On, from 32.53 to 26.72 per cent for Heliosit, from 19.52 to 19.58 per cent for Reliance, and 23.58 per cent for Mirage Dual Cure. The results of this study suggest that fluoride-releasing composites may have a caries preventive effect around orthodontic brackets.

Diastema Closure: A Case Report

This clinical study describes two combined modalities of treatment, orthodontic and porcelain laminate placement, to facilitate diastema closure. Geristore, a dual-cure fluoride-releasing composite was mixed to bond orthodontic brackets in place. H6 elastic bands were used with the orthodontic brackets to close the diastemas sufficiently and to allow the placement of Cerinate porcelain laminates to produce a beneficial cosmetic effect.