A comparison of fluoride release by resin-modified GIC and polyacid-modified composite resin.

The objective of this study was to compare the fluoride release of 2 fluoride-containing orthodontic adhesives from bracketed teeth and adhesive disks, a resin-modified glass ionomer cement (Fuji Ortho LC, encapsulated; GC America Corp, Aslip, Ill) and a polyacid-modified composite resin (Assure; Reliance Orthodontic Products, Itasca, Ill). A composite resin without fluoride (Transbond XT; 3M Unitek, Monrovia, Calif) was used as a reference control. Metal brackets were bonded to the buccal surfaces of 120 human premolars (40 teeth per adhesive), and disks were made from each adhesive. The deionized storage water was changed, and fluoride release was measured at specified intervals up to 28 days for the bracketed teeth and up to 150 days for the disks. Fuji Ortho LC released 75% more accumulated fluoride than Assure (6.61 microg/bracket vs 3.77 microg/bracket) from bracketed teeth over the 28-day observation period. Assure released more fluoride per day than did Fuji Ortho LC from the disks during the first 3 months. For the rest of the 150-day period, Fuji Ortho LC released more fluoride per day than did Assure. The amount of fluoride released by these materials varied dramatically with different water-changing protocols. The large discrepancy between fluoride released from disks compared with that released from bracketed teeth suggests that caution must be used in extrapolating fluoride-release levels of adhesive disks to in vivo treatment conditions.     

Long-term in vitro fluoride release and rerelease from orthodontic bonding materials containing fluoride.

The purpose of this study was to compare in vitro long-term (30 month) fluoride release and rerelease rates (after fluoride exposure) from 3 orthodontic bonding materials containing fluoride and 1 without fluoride. Ten samples of each material (Python, TP Orthodontics, LaPorte, Ind; Assure, Reliance Orthodontic Products, Itasca, Ill; Fuji Ortho LC, GC America, Alsip, Ill; and Transbond XT, 3M Unitek, Monrovia, Calif) were fabricated and stored in deionized distilled water at 37 degrees C. Five samples had fluoride-release rates measured at days 546, 637, 730, 821, and 913 after initial fabrication, and 5 samples were exposed to fluoride (Nupro 2% NaF gel, Dentsply Canada, Woodbridge, Ontario, Canada) for 4 minutes at day 535 and had measurements taken on days 546, 548, 552, 575, 637, 730, 821, and 913. To prevent cumulative measurements, the storage solutions were changed 24 hours before measurement. Statistically significant differences were found in fluoride-release rates (P <.0001), with Fuji Ortho LC releasing the most fluoride, followed by Python and Assure at all time points in the nonfluoride exposed group. In the fluoride-exposed group, there were significant differences in fluoride release (P <.0001), with Fuji Ortho LC releasing the most fluoride. A "burst-effect" pattern of fluoride release was seen after fluoride exposure for all materials. It was concluded that Fuji Ortho LC, Assure, and Python might have sufficient long-term fluoride-release rates to reduce white spot formation, and all are recommended as suitable fluoride-releasing orthodontic bonding materials.     

Comparison of bond strength of three adhesives: composite resin, hybrid GIC, and glass-filled GIC.

The objective of this study was to compare 3 orthodontic adhesives in the areas of shear-peel bond strength, location of adhesive failure, and extent of enamel cracking before bonding and after debonding of orthodontic brackets. The adhesives included a composite resin control (Transbond XT; 3M/Unitek, St Paul, Minn), a resin-modified glass ionomer cement (Fuji Ortho LC; GC America Corp, Alsip, Ill), and a polyacid-modified composite resin under dry and saliva-contaminated conditions (Assure; Reliance Orthodontic Products Inc, Itasca, Ill). Metal brackets were bonded to the buccal surfaces of 160 (4 groups of 40) human premolars. The bonded teeth were stored in deionized water at 37 degrees C for 30 days and thermocycled for 24 hours before debonding with a Universal Instron (Instron Corp, Canton, Mass) testing machine. The extent of cracking in the buccal surfaces was evaluated under 16x magnification before bonding and after debonding. Although the bond strength of the composite resin control (20.19 MPa) was significantly greater (P <.05) than that of the adhesives in the other groups, clinically acceptable shear-peel bond strengths were found for all adhesives (Fuji Ortho LC = 13.57 MPa, Assure-dry = 10.74 MPa, Assure-wet = 10.99 MPa). The bond strength for the Assure adhesive was not significantly affected by saliva contamination. The sample of extracted premolars used in this study displayed a greater frequency of buccal surface enamel cracking (46.7%) than that reported in the literature for in vivo premolars (7.8%-10.2%), which was possibly due to the extraction process. The frequency of enamel cracking in a subset of this sample (n = 34) increased from 46.4% at prebonding to 62.4% at postdebonding as a result of the forces of debonding.     

Fluoride release from new light-cured orthodontic bonding agents.

The purpose of this study was to compare the rates of fluoride release with time from 1 nonfluoridated and 3 fluoride-containing orthodontic bonding materials in distilled water and artificial saliva. Materials tested were Assure (Reliance Orthodontic Products, Itasca, Ill), Fuji Ortho LC (GC, Tokyo, Japan), Python (TP Orthodontics, LaPorte, Ind), and Transbond XT (3M Dental Products, Monrovia, Calif). Ten specimens of each material type were stored in distilled water, and 10 of each type were stored in artificial saliva at 37 degrees C. Fluoride release was measured with an ion-specific electrode. Readings were taken periodically for a total time period of 6 months. At day 1, Assure released the most fluoride into distilled water (66.2 microg/cm(2)) and into artificial saliva (65.8 microg/cm(2)), followed by Fuji Ortho LC (25.9 microg/cm(2); 18.8 microg/cm(2)), Python (6.3 microg/cm(2); 4.2 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The fluoride release rates were highest during the first days of testing, declining to lower but more stable levels. At the end of 6 months, Fuji Ortho LC released the most fluoride (3.8 microg/cm(2); 3.5 microg/cm(2)) followed by Assure (3.1 microg/cm(2); 2.8 microg/cm(2)), Python (2.6 microg/cm(2); 1.7 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The type of storage medium did not dramatically affect fluoride release. The second part of the study, undertaken after a year of sample storage, tested the 20 samples of Assure for a further 2-week period, after exposure to running and still distilled water. Although fluoride release rates declined with time, they were still higher than the 1.5 microg/cm(2) level that is referenced as inhibiting decalcification of enamel in a clinical environment. Release rates were similar in running and still water at all time points. Throughout the 6-month period, all 3 fluoride-containing materials had rates of fluoride release that could theoretically inhibit decalcification of enamel.     

Effect of brushing on fluoride release from 3 bracket adhesives.

The purpose of this in vitro study was to compare fluoride ion release from 3 orthodontic bracket adhesives with and without brushing the bracketed teeth with a fluoridated dentifrice. The bracket adhesives included a light-cured composite resin (Transbond; 3M Unitek, Monrovia, Calif), a fluoride-releasing composite resin (Advance; L D Caulk Division, Dentsply International, Milford, Del), and a resin-modified glass ionomer (Fuji Ortho LC; GC America, Alsip, Ill). The teeth in the control group were not bonded with brackets. Sixty extracted human teeth were randomly assigned to 6 groups of 10 each: (1) Transbond, brushed; (2) Advance, brushed; (3) Advance, not brushed; (4) Fuji, brushed; (5) Fuji, not brushed; and (6) control, brushed. After bonding, each tooth was placed in a sealed plastic test tube containing 4 ml of deionized water. The toothpaste used in brushing contained 0.15% weight per volume sodium fluoride, 1500 parts per million parts fluoride (Winter-fresh gel; Colgate-Palmolive Co., New York, NY). Brushing began 24 hours after the teeth were bonded and placed in deionized water. After brushing, the teeth were thoroughly rinsed with deionized water and returned to a sealed test tube. Fluoride measurements were taken before brushing began, at intervals of 72 hours for 22 days, and 90 and 93 days after bonding. Findings included: (1) brushing significantly increased the release of fluoride ions from the teeth in the composite resin and control groups, (2) the enamel crowns of the unbonded control teeth absorbed and re-released a substantial amount of fluoride ions obtained from the toothpaste, (3) the brushed group of teeth bonded with the fluoride-releasing composite resin released significantly more fluoride on the last 4 days that measurements were taken after brushing than the nonbrushed group bonded with the same adhesive, (4) the brushed group of teeth bonded with the resin-modified glass ionomer released significantly more fluoride on the last 4 days that measurements were taken after brushing than the nonbrushed group bonded with the same adhesive, and (5) all groups released small amounts of fluoride ions 90 and 93 days after bonding (68.5 and 71.5 days after brushing ended); the resin-modified glass ionomer groups released significantly more fluoride than the other groups. Brushing with fluoridated toothpaste produced significantly greater fluoride release from teeth bonded with all 3 adhesives, and from the unbonded control teeth.     

Effect of fluoride varnish on demineralization adjacent to brackets bonded with RMGI cement.

Far too often a less-than-optimal esthetic result occurs after orthodontic treatment due to demineralization of enamel adjacent to fixed orthodontic appliances in patients with inadequate oral hygiene. In vitro studies have shown that a resin-modified glass ionomer (RMGI) cement and a fluoride varnish might help clinicians combat this problem. The purpose of this study was to evaluate, in vitro, the effect of a fluoride-releasing cavity varnish on inhibition of enamel demineralization adjacent to orthodontic brackets bonded with RMGI and composite resin cements. Brackets were bonded to 48 extracted human third molars. Half were bonded with a composite resin (Transbond, 3M Unitek, Monrovia, Calif) and half with an RMGI (Fuji Ortho LC, GC America, Alsip, Ill). Each group was further divided into 2, with half receiving an application of fluoride-releasing varnish (Duraflor, Pharmascience, Montreal, Québec, Canada). The samples were cycled in an artificial caries solution for an hour twice daily for 31 days. After each caries challenge, the teeth were brushed with a soft toothbrush to simulate normal mechanical wear of the varnish. The loss of fluoride varnish was timed. Teeth were sectioned longitudinally and photographed under polarized light microscopy. Mean lesion depth was measured, and analysis of variance (ANOVA) (P 相似文献   

Comparison of bond strength between a conventional resin adhesive and a resin-modified glass ionomer adhesive: an in vitro and in vivo study.

The objectives of this study were (1) to compare the in vivo survival rates of orthodontic brackets bonded with a resin-modified glass ionomer adhesive (Fuji Ortho LC; GC America, Alsip, Ill) after conditioning with 10% polyacrylic acid and a conventional resin adhesive (Light Bond; Reliance Orthodontic Products, Itasca, Ill) bonded with 37% phosphoric acid, (2) to compare the in vitro bond shear/peel bond strength between the 2 adhesives, (3) to determine the mode of bracket failure in the in vivo and in vitro tests according to the adhesive remnant index (ARI), and (4) to compare the changes in surface morphology of enamel surface after etching or conditioning with 10% polyacrylic acid, with scanning electron microscopy. In the in vitro study, 50 extracted premolars were randomly divided into 4 groups: brackets bonded with Fuji Ortho LC or Light Bond adhesive that were debonded after either 30 minutes or 24 hours. Bond strengths were determined with a testing machine at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and a paired Student t test. The in vivo study consisted of 398 teeth that were randomly bonded with Fuji Ortho LC or Light Bond adhesive in 22 subjects with the split-mouth technique. Bracket survival rates and distribution were followed for 1.3 years. Data were analyzed with Kaplan-Meier product-limit estimates of survivorship function. The in vitro study results showed significant differences (P <.05) among the adhesives and the debond times. Light Bond had significantly greater bond strengths than Fuji Ortho LC at 24 hours (18.46 +/- 2.95 MPa vs 9.56 +/- 1.85 MPa) and 30 minutes (16.19 +/- 2.04 MPa vs 6.93 +/- 1.93 MPa). Mean ARI scores showed that Fuji Ortho LC had significantly greater incidences of enamel/adhesive failure than Light Bond adhesive (4.9 vs 4.1). For the in vivo study, no significant differences in failure rate, sex, or location in dental arch or ARI ratings were found between the 2 adhesives. These results suggest that, compared with conventional resin, brackets bonded with resin-modified glass ionomer adhesive had significantly less shear bond strength in vitro. However, similar survival rates of the 2 materials studied after 1.3 years indicate that resin-reinforced glass ionomers can provide adequate bond strengths clinically. The weaker chemical bonding between the adhesive and the enamel might make it easier for clinicians to clean up adhesives on the enamel surface after debonding.     

A self-conditioner for resin-modified glass ionomers in bonding orthodontic brackets

OBJECTIVE: To evaluate a new self-etch conditioner used with resin-modified glass ionomers (RMGIs) in bonding orthodontic brackets. MATERIALS AND METHODS: Sixty human molars were cleaned, mounted, and randomly divided into three groups. In group 1 (control), 20 orthodontic brackets were bonded to teeth using Transbond Plus Self-etching Primer; in group 2, 20 brackets were bonded using an RMGI with a 10% polyacrylic acid conditioner. In group 3, 20 brackets were bonded using Fuji Ortho LC with a new no-rinse self-conditioner for RMGIs. The same bracket type was used on all groups. The teeth were debonded in shear mode using a universal testing machine, and the amount of residual adhesive remaining on each tooth was evaluated. Analysis of variance was used to compare the shear bond strength (SBS), and the chi(2) test was used to compare the Adhesive Remnant Index (ARI) scores. RESULTS: There were no significant differences in the SBS (P = .556) between the groups. The mean SBS for Transbond Plus was 8.6 +/- 2.6 MPa, for Fuji Ortho LC using 10% polyacrylic acid 9.1 +/- 4.6 MPa, and for Fuji Ortho LC using GC Self-conditioner 9.9 +/- 4.1 MPa. The comparisons of the ARI scores between the three groups (chi(2) = 35.5) indicated that bracket failure mode was significantly different (P < .001), with more adhesive remaining on the teeth bonded using Transbond. Conclusions: The new self-etch conditioner can be used with an RMGI to successfully bond brackets. In addition, brackets bonded with Fuji Ortho LC resulted in less residual adhesive remaining on the teeth.     

In vitro study of 24-hour and 30-day shear bond strengths of three resin–glass ionomer cements used to bond orthodontic brackets

Interest in using composite resin–glass ionomer hybrid cements as orthodontic bracket adhesives has grown because of their potential for fluoride release. The purpose of this pilot study was to compare shear bond strengths of three resin–glass ionomer cements (Advance, Fuji Duet, Fuji Ortho LC) used as bracket adhesives with a composite resin 24 hours and 30 days after bonding. The amount of adhesive remaining on the debonded enamel surface was scored for each adhesive. Mesh-backed stainless-steel brackets were bonded to 100 extracted human premolars, which were stored in artificial saliva at 37° C until being tested to failure in a testing machine. The hybrid cements, with one exception, had bond strengths similar to those of the composite resin at 24 hours and 30 days. Fuji Ortho LC had significantly lower bond strengths (ANOVA p ≤ 0.05) than the other adhesives at 24 hours and 30 days when it was bonded to unetched, water-moistened enamel. Adhesive-remnant scores were similar for all cements, except for cement Fuji Ortho LC when it was bonded to unetched enamel. The resin–glass ionomer cements we tested appear to have bond strengths suitable for routine use as orthodontic bracket–bonding adhesives. (Am J Orthod Dentofacial Orthop 1998;113:620-24.)     

Changes in the enamel after in vitro debonding of brackets bonded with a modified glass ionomer cement

The aim of this study was to assess the incidence on the enamel behavior of debonding two types of orthodontic brackets, bonded with two different adhesives. Ninety recently extracted human premolars were bonded with two types of brackets (30 Minitrim and 60 Discovery). Two bonding protocols were used. The first one consisted in bonding 30 Minitrim and 30 Discovery brackets on etched and dried enamel surfaces with No Mix orthodontic resin. The second one consisted in bonding 30 Discovery brackets on unetched and wet enamel surfaces with a modified glass ionomer cement, Fuji Ortho LC. Teeth were stored in hydrated ambiance at 37 degrees C for 7 days before debonding. A LLOYD (LR 30K) testing machine was used to evaluate the orthogonal tensile bond strength. The debonded base brackets were examined with a scanning electron microscope (JEOL JSM 6400) and qualitatively analyzed with an OXFORD-LINK-ISIS to assess the site of bond failure and the enamel detachments. An Enamel Detachment Index (EDI) was defined. The results showed that the types of orthodontics brackets and adhesives influenced the bond strength and the enamel detachment. The Discovery/No Mix couple presented higher bond strength (214.9 N) than observed with the Discovery/Fuji Ortho LC (98.5 N) or the Minitrim/No Mix (82.3 N) couples. The surfaces of enamel detachment were insignificant and not extended for all brackets. Nevertheless, the Discovery/No Mix couple presented 42% of an EDI score of 1, compared to the Discovery/Fuji Ortho LC and Minitrim/No Mix couples which presented, respectively, 8% an 20% of an EDI score of 1. The laser sculpted base (Discovery) bonded on unetched and wet enamel surfaces with the modified glass ionomer cement (Fuji Ortho LC) offers a good resistance to debonding forces and preserve enamel integrity.     

Comparison of bracket debonding force between two conventional resin adhesives and a resin-reinforced glass ionomer cement: an in vitro and in vivo study.

The purpose of this study was to compare the debonding force of orthodontic brackets bonded with two conventional resin adhesives (Resilience L3 and Light Bond) and a resin-reinforced glass ionomer cement (Fuji Ortho LC). For the in vitro part of the study, 80 extracted premolars were randomly divided into four groups. In groups A and B, brackets were bonded to unetched enamel using Fuji Ortho LC cement in wet and dry conditions, respectively. In groups C and D, brackets were bonded to etched enamel using Resilience L3 and Light Bond, respectively. Debonding force was determined using a servohydraulic testing machine at a crosshead speed of 1 mm/min. Data was analyzed using the ANOVA and Tukey-Kramer multiple comparison test at p<0.05. A significant difference was found in debonding force between unetched Fuji Ortho LC and the two conventional resins. There was no significant difference between the two conventional resins or between unetched resin-reinforced glass ionomer in the wet and dry conditions. For the in vivo part of the study, 30 patients were randomly assigned to one of the three bonding material groups. Bracket survival rates and distributions were obtained by following these patients for 1.2 years. Data was analyzed using the Kaplan-Meier product-limit estimates of survivorship function. Bond failure interface was determined using a modified adhesive remnant index (ARI). These results showed no significant difference between survival rates and distributions among the three bonding materials with respect to the type of malocclusion, type of orthodontic treatment, or location of bracket. There were significant differences between survival distributions of males and females in the unetched Fuji Ortho LC group and among type of teeth in the conventional resin groups. The predominant mode of bracket failure for the unetched Fuji Ortho LC cement was at the enamel-adhesive interface, and for conventional resins, the enamel-adhesive interface and the bracket-adhesive interface. These results suggest that resin-reinforced glass ionomer cement can withstand occlusal and orthodontic forces despite having a bond strength lower than that of conventional resin adhesives.     

Effect of fluoride application on shear bond strength of brackets bonded with a resin-modified glass-ionomer.

PURPOSE: The purpose of this study was to assess the effect of fluoride application at 3 different steps of the bonding process on the shear bond strength and bond failure site of a resin-modified glass ionomer cement. MATERIAL: Sixty stainless steel brackets were bonded to bovine incisors with Fuji Ortho LC (GC Europe, Leuven, Belgium) under 4 different enamel conditions: (1) uncontaminated enamel, (2) enamel precleaned with fluoride-containing prophylaxis paste, (3) 1.1% acidulated phosphate fluoride (APF) gel applied immediately before conditioning, and (4) 1.1% APF gel applied immediately before bonding. After bonding, all samples were stored in distilled water for 24 hours and subsequently tested in shear mode on a universal testing machine. RESULTS: No significant differences were found between groups 1 (uncontaminated enamel) and 2 (fluoride application during prophylaxis). Both groups showed significantly greater shear bond strength values than groups 3 (fluoride application before conditioning) and 4 (fluoride application before bonding). Groups 3 and 4 did not differ significantly. Moreover, no significant differences in debond locations were found among the 4 groups. CONCLUSIONS: Fluoride application during initial prophylaxis does not affect the bond strength values of Fuji Ortho LC, whereas it significantly lowers bond strength values when applied before both conditioning and bonding.     

Influence of Adhesives and Methods of Enamel Pretreatment on the Shear Bond Strength of Orthodontic Brackets

Aim

The objective of present study was to examine influence of adhesives and methods of enamel pretreatment on the shear bond strength (SBS) of orthodontic brackets. The adhesives used were resin-reinforced glass ionomer cements-GIC (Fuji Ortho LC) and composite resin (Transbond XT).

Material and Methods

The experimental sample consisted of 80 extracted human first premolars. The sample was divided into four equal groups, and the metal brackets were bonded with different enamel pretreatments by using two adhesives: group A-10% polyacrylic acid; Fuji Ortho LC, group B–37% phosphoric acid; Fuji Ortho LC, group C–self etching primer; Transbond XT, group D–37% phosphoric acid, primer; Transbond XT. SBS of brackets was measured. After debonding of brackets, the adhesive remnant index (ARI) was evaluated.

Results

After the statistical analysis of the collected data was performed (ANOVA; Sheffe post-hoc test), the results showed that significantly lower SBS of the group B was found in relation to the groups C (p=0.031) and D (p=0.026). The results of ARI were similar in all testing groups and it was not possible to determine any statistically significant difference of the ARI (Chi- square test) between all four experimental groups.

Conclusion

The conclusion is that the use of composite resins material with appropriate enamel pretreatment according to manufacturer’s recommendation is the “gold standard” for brackets bonding for fixed orthodontic appliances.Key words: orthodontic brackets, shear strength, adhesive, enamel preparation     

In vitro bond strengths of resin modified glass ionomer cements and composite resin self-cure adhesives: introduction of an adhesive system with increased bond strength and inhibition of decalcification

This study evaluated the shear bond strength and adhesive remnant index of 5 self-cure adhesives to comparatively evaluate a new adhesive system. Extracted human incisors were randomly divided into 7 test groups of 20 each. Incisor mesh-backed brackets were bonded to the tooth specimens in each group with their respective adhesive according to the manufacturer's instructions. The specimens were thermocycled for 2 weeks at temperatures from 5 degrees to 55 degrees C to simulate oral conditions and debonded using an Instron machine. Acceptable bond strength parameters were present with the Contacto No-Mix (composite resin containing glass ionomer 8.75 MPa) and Fuji Ortho SC with acid conditioning (6.98 MPa). Contacto No-Mix had a higher bond strength (11.2 MPa) when microetching and Megabond were employed than when these adjuncts were not employed. When FUJI Ortho SC specimens were conditioned with polyacrylic acid, they showed a higher bond strength (6.98 MPa) than when bonded to unetched teeth (5.41 MPa). In test 3, EXPT-fluoride adhesive (AF) demonstrated a higher bond strength (13.44 MPa) than both resin composite Contacto No-Mix (8.8 MPa, GAC 7.4 MPa) and FUJI Ortho SC (5.41 MPa). Expt AF (Test 3) and Concise had equal bond strengths, however, the former can potentially release fluoride from the glass ionomer. Although the Ex     

Fluoride release capacities of four different orthodontic adhesives.

The aim of this study was to evaluate the fluoride release capacities of four orthodontic light cured adhesives. Groups 1 and 2 were the composites, Transbond and Sequence; Groups 3 and 4 were the glass ionomer cements, Fuji Ortho LC and 3M. Ten disc shaped specimens were prepared from each adhesive, and placed into a 1 ml of distilled water at 37 degrees C. The measurements were taken every day for a week, then once a week till the end of the first month, and once in two weeks till the end of the third month. The total and daily released fluoride amount during the testing period was statistically analyzed. The difference between the composite and glass ionomer cements was obvious. All the groups were statistically different from each other (p < 0.001). When the daily fluoride release graphics were detected, a sudden decrease was seen for all the adhesives. The fluoride values of the composites decreased to almost zero after the second day. The glass ionomer cements showed a decrease, too, but, they remained at a high level.     

Daily exposure to fluoride mouthrinse produces sustained fluoride release from orthodontic adhesives in vitro

OBJECTIVES: To determine firstly, if sustained fluoride release can be achieved from five orthodontic adhesives: Ketac-Cem, Fuji ORTHO LC, Sequence, Transbond and Right-On, with daily exposure to fluoride mouthrinse in vitro, and secondly, if sustained fluoride release can be re-established from the same specimens, after an interruption in mouthrinse exposure. METHODS: Ten brackets were bonded to bovine incisors using each adhesive. Each adhesive group was divided equally into a test and a control sub-group. In phase 1 (42 days), the test sub-groups were exposed for 1min daily to fluoride mouthrinse (225 ppm), followed by immersion in de-ionised water for 42 days to deplete their fluoride reserves. Mouthrinse exposure was then resumed in phase 2 (28 days). Mean cumulative fluoride release (MCFR) was calculated for days 0-21 of phase 1 and for the plateau portion of the fluoride release curves in phase 1 (days 21-42) and phase 2 (days 7-28). RESULTS: During phase 1, the MCFR for each test sub-group was significantly greater than its control (p<0.05). There was no significant difference in MCFR between the curve plateau portion of phases 1 and 2 for all adhesives except Transbond, for which MCFR was less in phase 2 (p<0. 05). CONCLUSIONS: Sustained fluoride release occurred for each adhesive exposed daily to fluoride mouthrinse, at a level significantly greater than its control. After fluoride exhaustion, re-exposure to daily fluoride mouthrinse produced sustained fluoride release levels comparable to those prior to exhaustion, for all adhesives except Transbond.     

Shear bond strengths of two resin-modified glass ionomer cements to porcelain.

Shear bond strength of a composite resin adhesive (Concise) and two resin-modified glass ionomer cements (Fuji Ortho LC and Geristore) bonded to porcelain surface was tested. Orthodontic brackets were bonded to 120 porcelain disks (Finesse) etched with 9% HF. Samples were divided into six groups: (1) Concise, (2) Concise/silane, (3) Geristore, (4) Geristore/silane, (5) Fuji, (6) Fuji/silane. No statistical difference in mean shear bond strength was found between silanated Concise (15.8 MPa), Geristore (19.4 MPa), and Fuji (18.5 MPa) groups, which were significantly higher than nonsilanated groups. Porcelain fracture was observed in all silanated groups and nonsilanated Geristore group. We conclude that (1) silane increases bond strength to porcelain significantly for composite resin and resin-modified glass ionomer cement, (2) Concise, Geristore, and Fuji Ortho LC provide comparable shear bond strength to porcelain.     

Fluoride release of glass ionomer-based luting cements in vitro.

STATEMENT OF PROBLEM: There is considerable variation in generic formulation and in reported fluoride release from resin-modified glass ionomer luting cements. PURPOSE: This study compared fluoride release from 2 generically similar resin-modified glass ionomer luting cements (Vitremer and Advance) with release from 2 conventional glass ionomer luting cements (Ketac-Cem and Fuji I). MATERIAL AND METHODS: Ten specimen disks of each of the 4 luting cements were fabricated and immersed in deionized water in individual polystyrene jars. The jars were stored in a humidor at 37 degrees C between test periods. At the same time each day, for 28 days, fluoride release from each specimen disk was measured in parts per million by testing the storage water. RESULTS: The 4 luting cements tested showed an initial high concentration of fluoride release during the first week, followed by a gradual decrease over the study period. Vitremer luting cement demonstrated the greatest mean cumulative fluoride release in parts per million over the study period (198), followed by Fuji I (140), Ketac-Cem (110), and Advance (99) luting cements. CONCLUSIONS: Resin-modified glass ionomer luting cements showed fluoride release comparable to the conventional glass ionomer luting cements. Vitremer luting cement released more fluoride over the 28-day period than the other cements.     

Polymerization efficiency of glass-ionomer and resin adhesives under molar bands

OBJECTIVE: To determine the degree of cure of a light-cured resin-modified glass ionomer (RMGI) under molar bands compared with a light-cured resin and a dual-cured resin. MATERIALS AND METHODS: The 3 cements used were Fuji Ortho LC, Eagle Spectrum resin, and Variolink II dual-cure. Each sample was indirectly light cured for 20 seconds (10 seconds occlusally, 10 seconds cervically) under sections of molar bands, and the degree of cure was evaluated with micro-MIR FTIR spectroscopy. RESULTS: The RMGI exhibited a significantly higher mean degree of cure (55.31%) than both of the resins (Eagle 19.23%; Variolink II, 25.42%), which did not differ significantly at alpha = .05 level of significance. CONCLUSION: Higher degree of conversion can be obtained from RMGIs under molar bands compared with composite resin adhesives provided the proper curing technique is used.     

Shear bond strength comparison of two adhesive systems following thermocycling. A new self-etch primer and a resin-modified glass ionomer

OBJECTIVE: To compare the effects of a standardized thermocycling protocol on the shear bond strength (SBS) of two adhesive systems: a resin-modified glass ionomer and a composite resin used with a new self-etching primer. MATERIALS AND METHODS: Forty human molars were cleaned, mounted, and randomly divided into two groups. In group 1, brackets were bonded to the teeth using Fuji Ortho LC adhesive, and in group 2, the Transbond Plus system was used. The teeth were stored in water at 37 degrees C for 24 hours, thermocycled between 5 and 55 degrees C, and debonded using a universal testing machine. The enamel surface was examined under 10x magnification to determine the amount of residual adhesive remaining on the tooth. Student's t-test was used to compare the SBS and the chi-square test was used to compare the adhesive remnant index (ARI) scores. RESULTS: The mean SBS for the brackets bonded using the Fuji Ortho LC was 6.4 +/- 4.5 MPa, and the mean SBS for the Transbond Plus system was 6.1 +/- 3.2 MPa. The result of the t-test comparisons (t = 0.207) indicated that there was no significant difference (P = .837) between the two groups. The comparisons of the ARI scores (chi(2) = 0.195) indicated that bracket failure mode was not significantly different (P = .907) between the two adhesives. CONCLUSION: Although SBS and ARI scores were not significantly different for the two adhesives, clinicians need to take into consideration the other properties of the adhesives before using them.