Fluoride-releasing Adhesives Research Articles

Assessment of the Additive Effect of Remineralizing Agents in Combination With Fluoride Releasing Adhesives in the Prevention of Enamel Decalcification in Orthodontic Patients: An In Vitro Study.

Introduction Incorporation of remineralizing agents with fluoride-releasing bracket adhesives may prevent the development of white spot lesions (WSL) or reverse the established WSL in patients undergoing fixed orthodontic treatment. We aimed to find out how effectively casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride varnish (FV) can remineralize teeth when mixed with fluoride-releasing orthodontic adhesive. Materials and methods We randomly assigned a total of 60 premolar teeth, therapeutically extracted for orthodontic purposes, into two equal groups. Group I (n = 30) utilized fluoride-releasing adhesive (FR), and Group II (n = 30) bonded with non-fluoride adhesive (NFR). Based on the applied remineralizing agent, we further divided each of the two groups into three equal subgroups of 10: Group IA (FR+FV), Group IB (FR+CPP-ACP), Group IC (control-only FR), Group IIA (NFR+FV), Group IIB (NFR+CPP-ACP), and Group IIC (control-only NFR). Following bonding procedures, all the samples underwent pH cycling for 28 days, where the enamel samples were immersed in 20 ml of demineralizing solution for three hours, followed by immersion in 30 ml of remineralizing solution for 17 hours. The samples were analyzed for shear bond strength (SBS) on a universal testing machine and hardness values (HV) by the Vickers microhardness test (VMT) using the indentation method. We also evaluated the adhesive remnant index (ARI) scores to determine the site of bracket failure. Statistical analysis The shear bond strength (SBS) and hardness value (HV) were expressed as the mean, standard deviation (SD), and median for each subgroup. We used the non-parametric Kruskal-Wallis test to analyze the SBS and HV, followed by the Dunn-Bonferroni test for intra-pair differences. The ARI score was expressed as the frequency of the percentage distribution, and the difference in the distribution of ARI scores between the groups was assessed by the Cochran chi-square test. The probability (p) value equal to or less than 0.05 was considered statistically significant. Results The results show that Group IB, bonded with a fluoride-releasing adhesive and a CPP-ACP remineralizing agent surface treatment, has the highest HV of300.23 units. Group IIC (only NFR) has the lowest hardness of153.3 units, which is statistically significant (p < 0.001). However, the ARI scores are not statistically significant between the groups tested. Conclusion The bond strength of the adhesive and the surface hardness of the enamel increased with the addition of fluoride varnish and CPP-ACP to both the fluoride-releasing and non-fluoride-releasing adhesives.

Effect of Fluoride Release on Enamel Demineralization Adjacent to Orthodontic Brackets.

This study aimed to evaluate the ability of fluoride-releasing adhesives to inhibit enamel demineralization surrounding orthodontic brackets. Two groups of 40 sound human premolars were sectioned mesio-distally. The halves were varnished, and orthodontic brackets were bonded with different adhesive materials. An area 1 mm wide surrounding the brackets was left exposed. Each specimen was immersed daily in a pH cycle for 28 days. In the second group, the specimens were exposed daily to a fluoride solution (250 ppm F-) at 37°C. The fluoride release from different groups was measured. Quantitative light-induced fluorescence (QLF) was used to quantify fluorescence loss of enamel surfaces adjacent to the brackets. Results were statistically analyzed using ANOVA at (p<0.05). Fluoride released from the three fluoride-releasing adhesives was significantly higher (p<0.001) in the group with daily fluoride exposures than in the group without fluoride exposures. Enamel adjacent to brackets bonded with Fuji Ortho LC, Ketac Cem, and Dyract Cem showed significantly less (p<0.001) changes in (ΔQ) value (less demineralization) than enamel bonded with Transbond, the control adhesive material. Using fluoride-releasing adhesives significantly reduced the level of demineralization adjacent to orthodontic brackets.

Evaluation of the Effects of Topical Fluoride Varnish and Fluoride Releasing Adhesive on Shear Bond Strength of Orthodontic Brackets: An In Vitro Study.

The aim of this study was to evaluate the in vitro effects of topical fluoride varnish and fluoride-releasing adhesive on the shear bond strength (SBS) of orthodontic brackets. A total of 60 extracted premolars were bonded to 0.022, stainless steel brackets and equally divided into three groups (n = 20) based on the adhesive used-Group I- Transbond XT Plus color change (3M Unitek), Group II- Transbond XT followed by application of fluoride varnish, and Group III- Transbond XT (3M Unitek) adhesive and their bond strengths were compared. Brackets were debonded with a universal testing machine. The modified adhesive remnant index (ARI) was also recorded. Data were analyzed by using an analysis of variance, and a post hoc test was performed for multiple comparisons among the groups. There were no significant differences between the SBSs (p = 0.91) between the groups. Also, no significant difference was found in the modified ARI (p = 0.093). The orthodontic adhesives used in our study, with or without the application of topical fluoride varnish, did not have a significant effect on the bond strengths of brackets. Adhesives evaluated in this study can be successfully used for bonding brackets. Chauhan C, Mangla R, Gandhi G, et al. Evaluation of the Effects of Topical Fluoride Varnish and Fluoride Releasing Adhesive on Shear Bond Strength of Orthodontic Brackets: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(1):37-41.

Effect of ageing media on shear bond strength of metal orthodontic brackets bonded with different adhesive systems (A comparative in-vitro study)

Background: The aim of this study was to evaluate the shear bond strength (SBS) and adhesive remnant index (ARI) of different orthodontic adhesive systems after exposure to aging media (water storage and acid challenge). Materials and methods: Eighty human upper premolar teeth were extracted for orthodontic purposes and randomly divided into two groups (40 teeth each): the first group in which the bonded teeth were stored in distilled water for 30 days at 37°C, and the second group in which the bonded teeth were subjected to acid challenge. Each group was further subdivided into four subgroups (10 teeth each) according to the type of adhesive system that would be bonded to metal brackets: either non-fluoride releasing adhesive (NFRA), fluoride releasing adhesive (FRA), Fluoride releasing bond with self-etching primer (FRBSP), or powder and liquid orthodontic fluoride releasing adhesive (PLFRA). After 30 days of water storage and acid challenge ageing procedures, the SBS was determined using Instron testing machine with a crosshead speed of 1 mm/min. The ARI was assessed using a stereomicroscope with 10 X magnification. Result: The SBS testing revealed significant differences (p&lt; 0.05) among the four tested adhesive systems in water storage and acid challenge groups using ANOVA F-test. In both groups, the NFRA subgroup exhibited the highest mean SBS value, followed by FRASP, then FRA subgroups, while the PLFRA subgroup had the lowest value of mean SBS. The independent t-test showed non-significant differences in mean SBS values between water storage and acid challenge groups. In respect to the ARI analysis, the Chi-square test showed significant differences among the tested adhesive systems. Conclusion: The shear bond strength of the fluoride releasing adhesive system was less than that of the non-fluoride releasing adhesive system, but still above the clinically acceptable range.&#x0D;

Prevention of white spot lesion formation during treatment with fixed orthodontic appliances

One of the main disadvantages of orthodontic treatment with fixed appliances is the formation of demineralisations around the brackets. These demineralisations develop because the brackets produce an increased number of plaque retention sites and a change in the oral environment, resulting in a different plaque composition. To prevent the formation of these demineralisations several methods are used during orthodontic treatment. Using additional fluoride is the best solution, for example, rinsing daily with a fluoride mouthwash, applying a fluoride varnish during every scheduled check-up, or using toothpaste with a high concentration of fluoride. The last 2 methods are less effectively incorporated in daily practice in the Netherlands due to financial or time factors. Additional measures, like using fluoride-releasing adhesives, CPP-ACP(F) or a chlorhexidine rinse appear to be less effective in reducing demineralisations. It is also important to provide specific oral hygiene and dietary instructions, based on an individual risk assessment.

Effectiveness of different adjunctive interventions in the management of orthodontically induced white spot lesions: A systematic review of systematic reviews and meta-analyses.

The purposes of this review were to appraise the current evidence on the management of orthodontically induced white spot lesions (OIWSLs) and to choose the best evidence from among conflicting systematic reviews. The published literature was searched from inception through November 2019 in 5 databases. Only systematic reviews and/or meta-analyses were eligible for inclusion. Methodological quality was assessed using A Measurement Tool to Assess Systematic Reviews-2 (AMSTAR-2). The Jadad decision algorithm was applied to choose the best available evidence from among discordant reviews. Thirteen publications were included. The interventions reported in the management of OIWSLs were topical fluorides, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing products, fluoridecontaining bonding materials, laser therapy, resin infiltration, and micro-abrasion. The methodological quality of the reviews ranged between moderate and critically low according to the AMSTAR-2 tool. Based on the Jadad decision algorithm criteria, topical fluorides yielded a 25-30% prevention of OIWSLs; however, their effect on reversing OIWSLs was unclear. The CPP-ACP products were effective in both preventing and reversing OIWSLs. No differences were noted between fluoride-releasing adhesives and conventional adhesives. Laser irradiation was effective in preventing OIWSLs, with some concerns about the argon laser at a certain setting. Finally, there is a lack of reliable evidence supporting the efficacy of resin infiltration or micro-abrasion due to the limited number of available studies. Based on the currently available information, topical fluorides and laser irradiation are effective in preventing OIWSLs. The CPP-ACP products are effective in preventing and reversing OIWSLs. Fluoride-releasing adhesives have no effect on OIWSL prevention.

In Vitro Inhibition of Enamel Demineralisation by Fluoride-releasing Restorative Materials and Dental Adhesives.

To determine the ability of 5 contemporary fluoride-releasing restoratives and 3 fluoride-releasing adhesives to inhibit enamel demineralisation surrounding restorations, and the associations between inhibition and the levels of fluoride released from these materials. Five fluoride-releasing restoratives (Fuji IX GP, Ketac N100, Dyract Extra, Beautifil II and Wave) and 3 fluoride-releasing adhesives (Stae, Prime & Bond NT and Fluoro Bond II) were investigated. Eight disks of each material were prepared. Fluoride release was measured daily using a fluoride-ion-selective electrode for 15 days. Twenty-four cavities for each group were restored with a restorative and an adhesive. Specimens were subjected to thermal stress and stored for 30 days in saline solution. After a 15-day pH-cycling regimen, two 150-μm-thick sections were derived from each specimen. Enamel lesion depth was measured at 0, 100, and 200 μm from each restoration's margin via polarised light microscopy. Of the restoratives investigated, Fuji IX GP released the most fluoride. The fluoride-releasing restoratives tested exhibited shallower enamel lesions than did the control group at all distances tested (p < 0.05). Fuji IX GP yielded significantly lower enamel lesion depth than did the other experimental materials. The depths of enamel lesions did not differ significantly when comparing restoratives applied with a fluoride-releasing adhesive with those applied with a non-fluoride-releasing adhesive. The fluoride-releasing materials tested reduced enamel demineralisation but to different extents, depending on their levels of fluoride release. Fluoride-releasing adhesives did not influence enamel lesion formation.

In vivo effect of antibacterial and fluoride-releasing adhesives on enamel demineralization around brackets: A micro-CT study

The aim of this in vivo study was to investigate the preventive effect of two different adhesives on enamel demineralization and compare these adhesives with a conventional one. Fifteen patients requiring the extraction of their first four premolars for orthodontic treatment were included in the study. One premolar was randomly selected, and an antibacterial monomer-containing and fluoride-releasing adhesive (Clearfil Protect Bond, Kuraray Medical, Okayama, Japan) was used for orthodontic bracket bonding. Another premolar was randomly selected, and a fluoride-releasing and recharging orthodontic adhesive (Opal Seal, Ultradent Products, South Jordan, Utah) was used. One premolar was assigned as a control, and a conventional adhesive (Transbond XT, 3M Unitek, Monrovia, Calif) was used. The teeth were extracted after 8 weeks, and the demineralization areas of the 45 extracted teeth were analyzed using microcomputed tomography with software. There was no significant difference between the white spot lesion (WSL) rates of the adhesives (P > .05). The volumes of the WSLs varied from 0 to 0.019349 mm3. Although Opal Seal showed the smallest lesion volumes, there was no significant difference in volumetric measurements of the lesions among the groups (P > .05). The findings indicated no significant differences between the preventive effects of the adhesives used in this in vivo study over 8 weeks.

Effect of Fluoride-Releasing Adhesive Systems on the Mechanical Properties of Eroded Dentin.

The aim of the study was to evaluate the effect of erosive pH cycling with solutions that simulate dental erosion on Martens hardness (HMV) and elastic modulus (Eit) of dentin restored with fluoride-releasing adhesive systems. Twenty-seven bovine dentin slabs were restored with three adhesive systems: Adper Single Bond 2 total-etch adhesive system, One Up Bond F and Clearfil SE Protect fluoride-containing self-etching adhesive systems. The restorations were made with Filtek Z250. The HMV and Eit values at distances of 10, 30, 50 and 70 µm from the interface were evaluated using a dynamic ultra microhardness tester before and after immersion in deionized water, citric acid and hydrochloric acid (n=9). Data were submitted to repeated-measures ANOVA and Fisher's PLSD tests (=0.05). After erosive cycling, HMV values of dentin decreased in all groups. For dentin restored with Adper Single Bond 2, the lowest values were found closer to the hybrid layer, while for One Up Bond F and Clearfil SE Protect, the values remained unaltered at all distances. For dentin restored with fluoride-releasing adhesive systems, a decrease in Eit was found, but after 30 µm this difference was not significant. The acid substances were able to alter HMV and Eit of the underlying dentin. For fluoride-releasing adhesives, the greater the distance from bonded interface, the lower the Eit values. The fluoride in One Up Bond F and Clearfil SE Protect was able to protect the underlying dentin closer to the materials. In this way, the fluoride from adhesive systems could have some positive effect in the early stages of erosive lesions.

Microgaps and Demineralization Progress around Composite Restorations

This study investigated the influence of adhesives and marginal sealing on demineralization progress using optical coherence tomography (OCT). Cavities (4 × 2 mm) were prepared in bovine incisors and restored using Clearfil SE Protect (SP), Bond Force (BF), Scotchbond Universal (SB), or G-Bond Plus (GB), followed by Estelite Flow Quick flowable composite. The control group received no adhesive (n = 10). After 3-d incubation in artificial saliva and 10,000 thermal cycles, gaps at enamel and dentin margins were measured at 8 locations on cross-sectional images obtained from each restoration using swept-source OCT at 1310-nm wavelength. Specimens were demineralized using acidified gel (pH = 4.5) for 5 wk and scanned every week to monitor the lesion progress at the same marginal locations. Repeated-measures analysis of variance showed that demineralization period and adhesive type and their interaction had a significant effect on the lesion size in both substrates (P < 0.001). SP, BF, and SB had significantly lower enamel and dentin initial gaps than the control and GB (P < 0.05). Enamel lesion progress was slower in the fluoride-releasing adhesives SP and BF and significantly different from SB, GB, and the control (P < 0.001). SP and BF dentin lesions were significantly different from GB and the control (P < 0.001), but not from SB (P > 0.05). A significant positive correlation (P < 0.05) was found between initial gap length and formed lesion size in both substrates, which was stronger in enamel (r = 0.63) than dentin (r = 0.35). Microgaps forming at the margins of restorations depend on adhesives and significantly contribute to the progress of demineralization around the margins, while fluoride release may decrease the rate of progression.

Comparison of shear bond strength of self-etching fluoride releasing adhesives with and without pumice prophylaxis

Despite the advances in orthodontic material and treatment mechanics, the placement of fixed appliances increases the risk of enamel demineralization. The development of fluoride release adhesives has attracted considerable interests because the combined use of antimicrobials and fluoride enhances the cariostatic effect. To compare the shear bond strength (SBS) of fluoride release adhesives with established orthodontic adhesives and assess failure mode using adhesive remnant index (ARI). The present study included 80 maxillary premolars which were randomly divided into four groups (n = 20) and were further subdivided into two subgroups A - Pumice prophylaxis (PP) and subgroup B - No PP (n = 10). Stainless steel brackets were bonded with Transbond XT, Transbond plus (TP) color change adhesive, Light Bond, and Clearfil protect bond. After debonding, the ARI was used to assess the mode of bracket failure. The data were analyzed using two-way analysis of variance, Post-hoc Tukey Honest significant differences test, and Chi-square test. The mean SBS of Group 4 was comparably higher regardless of PP. Brackets bonded with TP showed a comparable SBS to conventional Transbond XT. The ARI scores were predominately 2. Fluoride releasing adhesives combined with antibacterial monomer can play a vital role in reducing white spot lesions by enhancing the cariostatic effect especially in noncompliant\medically compromised patients.

Effects of bonding materials on the mechanical properties of enamel around orthodontic brackets

To determine if the enamel around orthodontic brackets is significantly altered after demineralization followed by application of adhesives with and without fluoride-releasing ability. One hundred eight noncarious human premolars were divided into six groups of 18 each and exposed to a demineralization solution. Stainless steel brackets were bonded using two conventional composite resin etch-and-rinse systems, three self-etching primer (SEP) composite resin systems, and one resin-modified glass ionomer cement (RMGIC) system. One conventional and one SEP composite resin adhesive did not have fluoride-releasing ability, which was claimed for the other four adhesives. The elastic modulus and hardness of the enamel were determined with a nanoindenter at 10 equidistant depths ranging from 1-46 µm and at four regions: control (not exposed) enamel surface, under the adhesive, and at 50 µm and 100 µm from the bracket edges. Using the Kruskal-Wallis and Mann-Whitney U-tests (P < .0125 for statistical significance), these properties were compared at different regions. The same behavior was observed for values of elastic modulus and hardness. Significant differences were found within approximately 21 µm of the enamel surface for etching with 35% phosphoric acid or priming with SEP, but only minimal changes occurred for the SEP adhesive. Increases in near-surface elastic modulus and hardness of enamel were found with the SEP adhesive and RMGIC with fluoride-releasing ability. Clinical use of the fluoride-releasing adhesives investigated may prevent demineralization of enamel around brackets during orthodontic treatment.

Evaluation of demineralization adjacent to orthodontic bracket and bond strength using fluoride-releasing and conventional bonding agents

One of the most difficult problems encountered in orthodontic treatment with fixed appliance is the control of enamel demineralization around the brackets. Fluoride-releasing bonding adhesives were introduced to aid in the prevention of demineralization adjacent to orthodontic brackets. Hence, an in vitro study was conducted to evaluate and compare demineralization adjacent to the orthodontic bracket and the bond strength using fluoride-releasing adhesive and conventional adhesive. One hundred and twenty healthy extracted premolars were selected for the study and were divided into two groups, each group consisting of 60 teeth. Both groups were further divided into three subgroups consisting of 20 samples each. Samples of subgroups A and B were bonded with two prototypes of fluoride-releasing adhesives (i.e. Rely-a-bond and Tru-bond). Samples of subgroup C (ortho-one) were bonded with conventional non-fluoride-releasing adhesive. Group I samples were subjected to demineralization in an acidic medium (methyl cellulose buffered with acetic acid at a pH of 4.5) for 4 weeks, which were later observed under a stereomicroscope. Group II samples were tested for shear bond strength using the Instron Universal testing machine. Both fluoride-releasing adhesives showed statistically significant lower enamel demineralization around the bracket when compared with the conventional adhesive. There was no statistically significant difference on comparing the demineralization between the two prototypes of fluoride-releasing adhesive. Evaluation of shear bond strength revealed that there was no significant difference between the subgroups. Fluoride-releasing adhesives might aid in the prevention of demineralization adjacent to the orthodontic bracket with acceptable bond strength.

Shear bond strength of orthodontic brackets bonded with different self-etching adhesives

The purpose of this study was to compare the shear bond strength (SBS) of orthodontic brackets bonded with 4 self-etching adhesives. A total of 175 extracted premolars were randomly divided into 5 groups (n = 35). Group I was the control, in which the enamel was etched with 37% phosphoric acid, and stainless steel brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif). In the remaining 4 groups, the enamel was conditioned with the following self-etching primers and adhesives: group II, Transbond Plus and Transbond XT (3M Unitek); group III, Clearfil Mega Bond FA and Kurasper F (Kuraray Medical, Tokyo, Japan); group IV, Primers A and B, and BeautyOrtho Bond (Shofu, Kyoto, Japan); and group V, AdheSE and Heliosit Orthodontic (Ivoclar Vivadent AG, Liechtenstein). The teeth were stored in distilled water at 37 degrees C for 24 hours and debonded with a universal testing machine. The adhesive remnant index (ARI) including enamel fracture score was also evaluated. Additionally, the conditioned enamel surfaces were observed under a scanning electron microscope. The SBS values of groups I (19.0 +/- 6.7 MPa) and II (16.6 +/- 7.3 MPa) were significantly higher than those of groups III (11.0 +/- 3.9 MPa), IV (10.1 +/- 3.7 MPa), and V (11.8 +/- 3.5 MPa). Fluoride-releasing adhesives (Kurasper F and BeautyOrtho Bond) showed clinically acceptable SBS values. Significant differences were found in the ARI and enamel fracture scores between groups I and II. The 4 self-etching adhesives yielded SBS values higher than the bond strength (5.9 to 7.8 MPa) suggested for routine clinical treatment, indicating that orthodontic brackets can be successfully bonded with any of these self-etching adhesives.

A Review of Chemical-approach and Ultramorphological Studies on the Development of Fluoride-releasing Dental Adhesives Comprising New Pre-Reacted Glass Ionomer (PRG) Fillers

This paper reviews our recent studies on fluoride-releasing adhesives and the related studies in this field based on information from original research papers, reviews, and patent literatures. A revolutionary PRG (pre-reacted glass ionomer) filler technology--where fillers were prepared by the acid-base reaction of a fluoroaluminosilicate glass with polyalkenoic acid in water, was newly developed, and a new category as "Giomer" was introduced into the market. On fluoride release capability, SIMS examination revealed in vitro fluoride ion uptake by dentin substrate from the PRG fillers in dental adhesive. On bonding durability, it was found that the improved durability of resin-dentin bonds might be achieved not only via the strengthened dentin due to fluoride ion uptake from the PRG-Ca fillers, but also due to retention of relatively insoluble 4-AETCa formed around remnant apatite crystallites within the hybrid layer in 4-AET-containing self-etching adhesives. On ultramorphological study of the resin-dentin interface, TEM images of the PRG-Ca fillers revealed that the dehydrated hydrogel was barely distinguishable from normal glass fillers, if not for the concurrent presence of remnant, incompletely reacted glass cores. In conclusion, it was expected that uptake of fluoride ions with cariostatic effect from PRG-Ca fillers would endow dentin substrates with the benefit of secondary caries prevention, together with an effective and durable adhesion to dentin.

Effect of Fluoride-releasing Adhesives on Dentin

Fluoride-releasing materials can be expected to inhibit secondary caries and enhance remineralization of decalcified dentin underneath restorations. The aim of this study was to evaluate the inhibitory effect on secondary caries and remineralization of decalcified dentin by fluoride-releasing adhesives. Two commercial fluoride-releasing adhesives, Reactmer bond (RB, Shofu) and One-up bond F (OB, Tokuyama), and a commercial adhesive without fluoride release, Mac-bond II (MB, Tokuyama), were used in this study. For examination of the inhibitory effect, class V cavities were prepared on extracted human premolars and restored with a restorative material following the application of each adhesive. The restored teeth were incubated in bacterial medium for 14 days after storage for 14 days at 37℃, 100% humidity. For examination of remineralization of decalcified dentin, decalcified dentin was promoted by using a bacterial caries induction system at the cavity wall. The cavities were then restored with resin composite after application of each adhesive and incubated for 4 weeks at 37℃, 100% humidity. Microradiographs in the inhibitory test showed an acid-resistant layer adjacent to the restoration in the caries-like lesions. The acid- resistant layers in the RB and OB groups with fluoride release were thicker than that in the MB group. Microradiographs in remineralization tests showed that the radiopacities of the decalcified dentin layers in the RB and OB groups were significantly higher than that in the MB group without fluoride release. These results indicated that fluoride-releasing adhesives are effective in inhibiting wall lesions and in enhancing the remineralization of decalcified dentin.

Comparison of fluoride release protocols for in-vitro testing of 3 orthodontic adhesives

The objective of this study was to compare the fluoride release of 3 orthodontic adhesives using disks and bracketed teeth with different storage protocols. The adhesives used were a resin-modified glass ionomer (RMGI) (Fuji Ortho LC; GC America, Aslip, Ill), a polyacid-modified composite resin (PMCR)(Assure; Reliance Orthodontic Products, Itasca, Ill), and a composite control, Transbond XT (3M Unitek, Monrovia, Calif). Metal brackets were bonded to the buccal and lingual surfaces of 120 extracted human premolars. Five plastic containers holding 4 teeth (8 brackets) were used for each adhesive protocol. The samples were stored in containers holding 4 mL of deionized water at 37°C for 28 and 84 days for the brackets and disks, respectively. The bracketed samples released larger initial amounts of fluoride compared with the disk samples during the first 5 to 6 days for both fluoride-releasing adhesives. The PMCR (Assure) released more fluoride (mg/cm2/day) than did the RMGI (Fuji Ortho LC) in all protocols with the exception of daily protocols when values diminished below the RMGI values near the 24th day and between the 56th and the 70th days for the bracketed and disk samples, respectively. Inconsistent values for fluoride release were noted in the bracket and disk samples when compared with daily versus cumulative water changes. Daily water changes revealed higher fluoride release levels (brackets), but this trend was not evident in the disk samples. Daily water changes may yield more clinically relevant data on fluoride release. (Am J Orthod Dentofacial Orthop 2002;121:301-9)

In vitro evaluation of matrix-bound fluoride-releasing orthodontic bonding adhesives

Sustained fluoride-releasing composite resins have the potential to prevent decalcification of enamel that may occur during the course of orthodontic treatment. The purpose of this study was to evaluate the potential of matrix-bound fluoride-releasing adhesives (MBF) for orthodontic use by comparing the shear bond strengths (in MPa) and remnant adhesive on debonding (ARI scores) of these resins with commercially available orthodontic adhesives. Two types of resins were evaluated in separate groups: The light-cured resins (group I) consisted of two light-cured MBF, designated resins LA and LB, and five nonfluoride releasing resins, designated LC, LD, LE, LF, and LG. The self-cured resins (group II) consisted of one MBF, designated resin SA, and six nonfluoride releasing resins, designated resins SB, SC, SD, SE, SF, and SG. These resins were used to attach upper right central incisor metal (foil mesh based) orthodontic brackets to 210 freshly extracted bovine incisors in groups of 15 each. Student-Newman-Keuls multiple comparison tests were performed at p < 0.05 to determine significant differences among the resin types. Resin LA was significantly higher in bond strength (mean = 27.4 MPa) compared with LD and LG (mean = 18.9, 10.7 MPa, respectively). Further, LA demonstrated a higher mean bond strength compared with LB, LC, LE, and LF (mean = 21.9, 24.1, 24.3, and 20.8 MPa, respectively). Resin LB had significantly lower ARI scores (mean = 0.33) compared with LF and LG (mean = 1.20 and 1.80). LA, LB, LC, LD, and LE (mean = 0.47, 0.33, 0.60, 0.73, and 0.73, respectively) were not significantly different in their ARI scores. Resin SB demonstrated significantly lower bond strength (mean = 17.2 MPa) compared with SC, SD, SE, SF, and SG (mean = 23.9, 23.7, 23.4, 23.8, and 22.9 MPa, respectively). Resin SA (mean = 19.0 MPa) was not significantly different in bond strength from SB, SC, SD, SE, SF, and SG. Resin SA demonstrated significantly lower ARI scores (mean = 0.73) compared with SD and SE (mean = 2.13 and 1.87). Resin SA had lower mean ARI scores compared with SB, SC, SF, and SG (mean = 1.00, 1.27, 1.13 and 0.87, respectively). Sustained fluoride-releasing (matrix-bound) orthodontic adhesive systems demonstrated bond strength and ARI scores that compared favorably with commercially available orthodontic adhesives.

Evaluation of fluoride release from an orthodontic bonding system

Decalcification around brackets is sometimes observed after orthodontic treatment. Fluoride-releasing orthodontic adhesives have been developed in an attempt to reduce the frequency and severity of decalcification. This study evaluated, in vitro, a light-activated, fluoride-releasing composite resin adhesive, FluorEver OBA. The findings indicate that FluorEver OBA released small concentrations of fluoride ions over time. A mean of 2.6 ppm was released on day 1, decreasing to a mean of 0.42 ppm by day 2 and to 0.04 ppm by day 43. The clinical implications of these findings are discussed.

The relevance of controlled fluoride release with bonded orthodontic appliances

The aim of this investigation was to study the inhibitory effect of fluoride-releasing adhesives on in vitro demineralization of uncovered enamel adjacent to a bonded orthodontic bracket. Bovine enamel, a glass-ionomer cement and a Bis GMA-based adhesive were used. Metal brackets were bonded to intact and acid-etched enamel, following this a number of the samples received an acidified fluoride (APF) application. Each sample was subjected to demineralization treatment in vitro, and subsequently sectioned and microscopically investigated for the formation of artificial caries. It is concluded that the fluoride-releasing glass-ionomer cement protected a substantial area of uncovered enamel adjacent to the cemented bracket. The opposite effect was observed for the Bis GMA adhesive. The artificial caries developed not only in the uncovered enamel, but also, to some extent, under the adhesive material. Topical fluoridation did not affect the results significantly.