Shear bond strength of a resin-reinforced glass ionomer cement: an in vitro comparative study

Comparison of bracket bond strength to etched and unetched enamel under dry and wet conditions using Fuji Ortho LC glass-ionomer

Background. Acid etching prior to orthodontic bracket bonding may result in enamel wear or cracks following bracket removal. The manufacturer of Fuji Ortho LC glass-ionomer (GI) claims that it can bond brackets to wet unetched enamel. This study aimed to compare the bracket bond strength to etched and unetched enamel under dry and wet conditions. Methods. In this in vitro study, 60 intact premolar teeth were randomly assigned to 6 groups (etched and dried, etched and moistened with distilled water, etched and moistened with saliva, unetched and dried, unetched and moistened with water, unetched and moistened with saliva). In all the groups, Leon 4 brackets were bonded to the enamel using Fuji Ortho LC GI. The teeth were immersed in distilled water at 37°C for 24 hours and subjected to shear loads at a crosshead speed of 5 mm/min in a Zwick machine for bond strength testing. Data were analyzed with ANOVA, Tukey test and independent t-test. Results . The mean bond strength values in groups 1 (etched, dry), 2 (etched, moistened with water), 3 (etched, moistened with saliva), 4 (unetched, dry), 5 (unetched, moistened with water) and 6 (unetched, moistened with saliva) were 21.86, 16.46, 10.49, 8.12, 9.15 and 9.52 MPa, respectively. Significant differences in bond strength were detected between groups 1 and 2 and all the other groups (P < 0.05), with no significant difference between groups 1 and 2 (P > 0.05). Conclusion. Fuji Ortho LC GI provided adequate bond strength between brackets and enamel. To acquire higher bond strength, brackets must be bonded to etched and dried enamel.

Influence of Water Storage and Bonding Material on Bond Strength of Metallic Brackets to Ceramic

This study investigated the influence of water storage (24 h and 6 months), and Transbond XT and Fuji Ortho LC bonding materials on the bond strength of metallic brackets bonded to feldspathic ceramic. Four cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 60 s. Each cylinder received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT or Fuji Ortho LC. Light-activation was carried out with 40 s total exposure time using Bluephase G2. Half the specimens for each bonding materials (n=20) were stored in distilled water at 37 °C for 24 h and the other half for 6 months. Shear bond strength testing was performed after storage times at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Data were subjected to two-way ANOVA and Tukey's test (p<0.05). Transbond XT showed significantly higher bond strength (p<0.05) than Fuji Ortho LC. Significant differences in bond strength (p<0.05) were found when 24 h and 6 months storage times were compared between materials. ARI showed a predominance of score 0 for all groups, and higher scores at 1, 2 and 3 for 24 h storage time. In conclusion, storage time and bonding materials showed significant influence on the bond strength of brackets to ceramic.

Effect of acid etching on bond strength of nanoionomer as an orthodontic bonding adhesive

AIMS

A new Resin Modified Glass Ionomer Cement known as nanoionomer containing nanofillers of fluoroaluminosilicate glass and nanofiller 'clusters' has been introduced. An in-vitro study aimed at evaluating shear bond strength (SBS) and adhesive remnant index (ARI) of nanoionomer under etching/unetched condition for use as an orthodontic bonding agent.

MATERIAL AND METHODS

A total of 75 extracted premolars were used, which were divided into three equal groups of 25 each: 1-Conventional adhesive (Enlight Light Cure, SDS, Ormco, CA, USA) was used after and etching with 37% phosphoric acid for 30 s, followed by Ortho Solo application 2-nanoionomer (Ketac(™) N100, 3M, ESPE, St. Paul, MN, USA) was used after etching with 37% phosphoric acid for 30 s 3-nanoionomer was used without etching. The SBS testing was performed using a digital universal testing machine (UTM-G-410B, Shanta Engineering). Evaluation of ARI was done using scanning electron microscopy. The SBS were compared using ANOVA with post-hoc Tukey test for intergroup comparisons and ARI scores were compared with Chi-square test.

RESULTS

ANOVA (SBS, F = 104.75) and Chi-square (ARI, Chi-square = 30.71) tests revealed significant differences between groups (P < 0.01). The mean (SD) SBS achieved with conventional light cure adhesive was significantly higher (P < 0.05) (10.59 ± 2.03 Mpa, 95% CI, 9.74-11.41) than the nanoionomer groups (unetched 4.13 ± 0.88 Mpa, 95% CI, 3.79-4.47 and etched 9.32 ± 1.87 Mpa, 95% CI, 8.58-10.06). However, nanoionomer with etching, registered SBS in the clinically acceptable range of 5.9-7.8 MPa, as suggested by Reynolds (1975). The nanoionomer groups gave significantly lower ARI values than the conventional adhesive group.

CONCLUSION

Based on this in-vitro study, nanoionomer with etching can be successfully used as an orthodontic bonding agent leaving less adhesive remnant on enamel surface, making cleaning easier. However, in-vivo studies are needed to confirm the validity of present findings.

Influence of Light Source, Thermocycling and Silane on the Shear Bond Strength of Metallic Brackets to Ceramic

The objective of this study was to evaluate the effects of different light sources, thermocycling and silane on the bond strength of metallic brackets to ceramic. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 60 s. Half of the cylinders (Groups 1 to 4) received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT and divided into 8 groups (n=20), according to light source (Radii Plus LED - 40 s; Groups 1, 2, 5 and 6 and XL 2500 halogen light - 40 s; Groups 3, 4, 7 and 8) and experimental conditions with (Groups 2, 4, 6 and 8) without thermocycling (Groups 1, 3, 5 and 7). Shear bond testing was carried out after 24 h of deionized water storage (Groups 1, 3, 5 and 7) and thermocycling (Groups 2, 4, 6 and 8; 7,000 cycles - 5°/55 °C). Date were submitted to three-way ANOVA and Tukey's post hoc test (α=0.05). The Adhesive Remnamt Index (ARI) was evaluated at 8× magnification. The application of silane was effective in increasing the shear bond strength of the brackets to ceramic (p<0.05). Significant difference (p<0.05) on the bond strength was observed between light sources with or without thermocycling. The ARI showed a predominance of scores 0 for all groups, with an increase in scores 1, 2 and 3 for the silane groups. In conclusion, silane improved significantly the shear bond strength of the brackets to ceramic. The thermocycling and light sources influence on the bond strength.

Shear bond strength of metallic and ceramic brackets using color change adhesives

OBJECTIVE

To determine the shear bond strength of orthodontic brackets using color change adhesives that are supposed to aid in removing excess of bonding material and compare them to a traditional adhesive.

METHODS

Ninety metallic and ninety ceramic brackets were bonded to bovine incisors using two color change adhesives and a regular one. A tensile stress was applied by a universal testing machine. The teeth were observed in a microscope after debonding in order to determine the Adhesive Remnant Index (ARI).

RESULTS

The statistical analysis (ANOVA, Tukey, and Kruskall-Wallis tests) demonstrated that the mean bond strength presented no difference when metallic and ceramic brackets were compared, but the bond resistance values were significantly different for the three adhesives used. The most common ARI outcome was the entire adhesive remaining on the enamel.

CONCLUSIONS

The bond strength was similar for metallic and ceramic brackets when the same adhesive system was used. ARI scores demonstrated that bonding with these adhesives is safe even when ceramic brackets were used. On the other hand, bond strength was too low for orthodontic purposes when Ortho Lite Cure was used.

Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic.

Repeated bonding of fixed retainer increases the risk of enamel fracture

The aim of this study was to investigate the influences of repeated bonding, using 2 different orthodontic adhesive systems, on the shear bond strength (SBS) and the enamel surface morphology. Sixty premolars were divided into 2 groups (n = 30), and either Transbond XT (T group) or Fuji Ortho LC (F group) adhesives were used. SBS was measured 24 h after bonding, using a universal testing machine. Then, the enamel surfaces were investigated and the mode of failure was described using adhesive remnant index (ARI) scores. After each debonding, 10 teeth from each group were examined by scanning electron microscopy to determine the penetration of adhesives, the length of resin tags, and the state of the enamel surface. The other teeth were subjected to two more bonding/debonding procedures. In T group, the second debonding sequences had significantly higher bond strengths than the other sequences. The length of resin tags was greatest in the second debonding sequence, although there was no significant difference. In F group, the SBS increased with further rebonding and the failure mode tended towards cohesive failure. In both groups, the ARI scores increased with rebonding. Enamel loss could have occurred with both adhesives, although the surfaces appeared unchanged to the naked eye. From this study, we suggest that enamel damage caused by repeated bonding is of concern. To prevent bond failure, we should pay attention to the adhesion method used for bondable retainers.

Resin-modified glass ionomer cements for bonding orthodontic retainers

The aims of this study were to evaluate the shear bond strength (SBS), fracture mode, and wire pull out (WPO) resistance between resin-modified glass ionomer cement (RMGIC) and conventional orthodontic composite used as a lingual retainer adhesive. Forty lower human incisors were randomly divided into two equal groups. To determine the SBS, either Transbond-LR or Fuji Ortho-LC was applied to the lingual surface of the teeth by packing the material into cylindrical plastic matrices with an internal diameter of 2.34 mm and a height of 3 mm (Ultradent) to simulate the lingual retainer bonding area. To test WPO resistance, 20 samples were prepared for each composite where the wire was embedded in the composite material and cured, 20 seconds for Transbond-LR and 40 seconds for Fuji Ortho-LC. The ends of the wire were then drawn up and tensile stress was applied until failure of the resin. A Student's t-test for independent variables was used to compare the SBS and WPO data. Fracture modes were analyzed using Pearson chi-square test. Significance was determined at P < 0.05. The SBS values were 24.7 +/- 9.2 and 10.2 +/- 5.5 MPa and the mean WPO values 19.8 +/- 4.6 and 11.1 +/- 5.7 N for Transbond-LR and Fuji Ortho-LC, respectively. Statistical analysis showed that the SBS and WPO values of Transbond-LR and Fuji Ortho-LC were significantly different (P < 0.001). No significant differences were present among the groups in terms of fracture mode. However, the RMGIC resulted in a significant decrease in SBS and WPO; it produced sufficient SBS values on the etched enamel surfaces, when used as a bonded orthodontic retainer adhesive.

[Methods of bonding to the enamel in orthodontics]

Mastery of the bonding stage of treatment is clearly a critical step in the clinical practice of orthodontics. There is such a wide variety of products available in orthodontics that a reasoned assessment of bonding systems is a practical necessity. Composite plastics, associated with hydrophobic or hydro-compatible adhesive systems, and the CVIMAR represent the two principal types of bonding agents used in dentistry. They are categorized according to their constituents into a wide range of products whose nuanced differences are sometimes difficult to discern. This paper first focuses on the development of the composition of the various materials, a depiction of the fundamental parameters of adhesion, and a detailed terminology to help the reader reach a basic understanding. Bonding systems are designed to fulfill the requirements of specific clinical situations. A description of their modes of adhesion, of their composition, and of their advantages and disadvantages will be presented in the second part of this article.

In-vivo effects of fluoridated antiplaque dentifrice and bonding material on enamel demineralization adjacent to orthodontic appliances

INTRODUCTION

The effect of a fluoridated antiplaque dentifrice on the development of caries lesions adjacent to dental appliances bonded with ionomeric material is unknown.

METHODS

Fourteen orthodontic patients were randomly divided into 2 groups of 7. One group brushed 3 times a day with a fluoridated dentifrice, and the other used an experimental antiplaque fluoridated formulation. Bracket bases were randomly bonded with either resin-modified glass ionomer cement or composite resin to the buccal surfaces of either the maxillary left or right premolars in each subject. The teeth were banded, leaving a space on the buccal surface to allow dental plaque accumulation. After 28 days of dentifrice use, the teeth were extracted, and mineral loss in the enamel adjacent to the bonded material was assessed by cross-sectional microhardness.

RESULTS

Mineral loss in the enamel surrounding the bond with the resin-modified glass ionomer cement was lower (P <.05) than around the composite bond. Enamel demineralization was lower (P <.05) in subjects who used the experimental antiplaque fluoridated formulation than in those who used the fluoridated one.

CONCLUSIONS

The data suggest that an antiplaque fluoridated dentifrice is superior to one that is only fluoridated for reducing enamel demineralization adjacent to dental material bonded with composite, but the effect seems irrelevant when bonding is done with the ionomeric material.

Effect of blood contamination on shear bond strength of brackets bonded with a self-etching primer combined with a resin-modified glass ionomer

This study assessed the effect of blood contamination on the shear bond strength and bond failure site of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium) used with 3 enamel conditioners (10% polyacrylic acid, 37% phosphoric acid, and self-etching primer). One hundred twenty bovine permanent mandibular incisors were randomly divided into 8 groups; each group consisted of 15 specimens. Two enamel surface conditions were studied: dry and contaminated with blood. One hundred twenty stainless steel brackets were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and then tested in shear mode on a testing machine. The groups conditioned with self-etching primer and 37% phosphoric acid had the highest bond strengths for both dry and blood-contaminated enamel. The groups conditioned with 10% polyacrylic acid showed significantly lower shear bond strength value, and the unconditioned groups had the lowest bond strengths. For each enamel conditioner, no significant difference was reported between dry and blood-contaminated groups. Significant differences in debond locations were found among the groups bonded with the different conditioners. Blood contamination of enamel during the bonding procedure of Fuji Ortho LC did not affect its bond strength values, no matter which enamel conditioner was used.

Effect of saliva on shear bond strength of an orthodontic adhesive used with moisture-insensitive and self-etching primers

The purpose of this study was to investigate the effect of saliva contamination on the shear bond strength of an orthodontic adhesive used with Transbond Moisture-Insensitive Primer (MIP, 3M Unitek, Monrovia, Calif) and Transbond Plus Self-Etching Primer (SEP, 3M Unitek). Hydrophobic Transbond XT primer (XT, 3M Unitek) was used as a control. A total of 162 extracted premolars were collected and divided equally into 9 groups of 18 teeth each, and brackets were bonded with Transbond XT adhesive (3M Unitek) under different experimental conditions: (1) control: etch/dry/XT, (2) etch/dry/MIP, (3) etch/dry/MIP/wet (saliva)/MIP, (4) etch/wet/MIP, (5) etch/wet/MIP/wet/MIP, (6) dry/SEP, (7) dry/SEP/wet/SEP, (8) wet/SEP, and (9) wet/SEP/wet/SEP. Shear bond strength of each sample was examined with a testing machine. The results showed that the control group had the highest mean shear bond strength (group 1, 21.3 +/- 6.8 MPa), followed by the MIP group in a dry field (group 2, 20.7 +/- 5.0 MPa). No significant difference was found between groups 1 and 2. Groups 3 through 9 had similar mean strengths, ranging from 12.7 to 15.0 MPa (P >.05), which were significantly lower than in groups 1 and 2 (P <.05). There was no significant difference in bond-failure site among the 9 groups. It was concluded that (1) Transbond XT adhesive with Transbond XT primer and MIP in a dry field yields similar bond strengths, which are greater than all other groups, (2) saliva contamination significantly lowers the bond strength of Transbond MIP, (3) saliva has no effect on the bond strength of Transbond SEP, (4) Transbond XT adhesive with Transbond MIP and SEP might have clinically acceptable bond strengths in either dry or wet fields.

Use of a self-etching primer in combination with a resin-modified glass ionomer: effect of water and saliva contamination on shear bond strength

The purpose of this study was to evaluate the effects of 3 different enamel conditioners (10% polyacrylic acid, 37% phosphoric acid, and self-etching primer) on the shear bond strength and site of bond failure of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium) bonded onto dry, water-moistened, and saliva-moistened enamel. One hundred eighty bovine permanent mandibular incisors were randomly divided into 12 groups; each group consisted of 15 specimens. Three different enamel surface conditions were studied: dry, soaked with water, soaked with saliva. One hundred eighty stainless steel brackets were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and then tested in a shear mode on a testing machine. After self-etching primer application, Fuji Ortho LC produced the highest shear bond strengths under all the different enamel surface conditions; these values were significantly higher than those achieved in the remaining groups, except when Fuji Ortho LC was used in combination with 37% phosphoric acid on dry enamel. Fuji Ortho LC bonded without enamel conditioning produced the lowest shear bond strengths. The bond strength of the groups conditioned with 10% polyacrylic acid was significantly lower than that of the groups etched with 37% phosphoric acid, except when both conditioners were used on enamel soaked with water.

Shear-peel bond strength of orthodontic primers in wet conditions

OBJECTIVE

The purpose of this in vitro study was to determine whether a hydrophilic primer (Transbond MIP, [MIP]) produces a significant difference in shear/peel bond strength compared with a traditional hydrophobic primer (Transbond XT, [XT]) in wet (W) or dry (D) conditions and if there is a difference in the site of bond failure.

DESIGN

A randomized blinded in vitro design.

SETTING AND SAMPLE POPULATION

The University of Missouri-Kansas City School of Dentistry. Forty extracted human premolars were divided into four test groups (n = 10 each): MIP-dry conditions (MIPD), MIP-wet conditions (MIPW), XT-dry (XTD) and XT-wet (XTW).

EXPERIMENTAL VARIABLE

Orthodontic brackets were bonded to the teeth according to the manufacturer's directions except XTW and MIPW were exposed to moisture.

OUTCOME MEASURE

Shear/peel test 24 h after bonding using an Instron at a crosshead speed of 0.5 mm/min and the adhesive remnant index to determine the site of bond failure.

RESULTS

The bond strengths (X +/- SD) in MPa were XTD = 8.3 +/- 2.3; XTW = 0.8 +/- 0.7; MIPD = 7.5 +/- 1.8 and MIPW = 7.9 +/- 1.7. The shear/peel bond strengths were significantly different: XTD = MIPD = MIPW > XTW (p < or = 0.01; two-way ANOVA; Tukey HSD). The ARI scores were also significantly different: XTD = MIPD = MIPW > XTW (p < or = 0.01; Chi-square).

CONCLUSIONS

Orthodontists who suspect moisture contamination should use a hydrophilic primer during bonding procedures to maintain shear/peel bond strength.

Effect of surface treatments on the bond strength of glass ionomers to enamel

OBJECTIVES

The objective of this study was to evaluate the effect of various surface treatments on the bond strength of several glass ionomers to enamel, and to examine the resulting bond interface.

METHODS

Ground bovine enamel specimens were divided into groups which were pretreated with one of the following: (1) no pretreatment, (2) Vitremer primer, (3) 10% polyacrylic acid or (4) 35% phosphoric acid. A conventional glass ionomer and two resin-modified glass ionomers (RMGI's) were bonded to the pretreated enamel surfaces, stored in water for 24h and shear bond strengths measured. RMGI's were tested as light-cured and self-cured materials. Transverse sections of similarly prepared samples were etched with phosphoric acid for 60s to partially remove enamel and expose the enamel/glass-ionomer interface. The interface morphology was examined by SEM.

RESULTS

Polyacrylic acid and phosphoric acid conditioning resulted in significantly increased bond strength to enamel for all three glass ionomer materials, compared to no pretreatment (p<0.01). Light-cured bond strengths were in most cases, significantly greater than when self-cured (p<0.01). Examination of the bonded interfaces revealed the presence of polymer tags in the enamel conditioned with polyacrylic acid and phosphoric acid.

SIGNIFICANCE

Conditioners significantly improved the bond to enamel for the conventional glass ionomer and RMGI's that were examined in this study. Micromechanical bonding may play a role in the mechanism of bonding glass ionomer to enamel.

An 18-month clinical study of bond failures with resin-modified glass ionomer cement in orthodontic practice

The purpose of this study was to evaluate, over an 18-month period, the clinical performances of a resin-modified glass ionomer cement for bonding orthodontic brackets and to analyze various factors that influenced their survival and failure rates. Two orthodontists using the edgewise technique participated in this study; 6113 brackets, including 20 molar tubes, were bonded with Fuji Ortho LC (GC, Europe, N.V. Leuven, Belgium) in 135 patients. Ceramic, metal, and resin brackets were tested, and both operators used the same bonding method for the brackets. The survival rate and the failure rate of the brackets were evaluated. The rates were determined by operator, bracket type, tooth position in the dental arch, and age and sex of the patients. Bracket survival rates were estimated using the Kaplan-Meier test. The Cox-Mantel statistical test with a level of significance set at 0.05 was used to compare survival curves. The chi-square test was used at a level of P < .05 to compare failure rates. The overall failure rate for the sample was 7%, and the overall survival rate was equal to 0.918. Age had no significant influence on the failure rate (P = .07); however, it had a significant influence on the survival rate (P < .01). The best survival rates were obtained in the groups aged 16 to 20 years (S[t] = 0.943) and older than 20 years (S[t] = 0.929). The difference between males and females was not statistically significant in terms of failure rate (P = .17). However, the Cox-Mantel test showed a higher bracket survival rate for the males (S[t] = 0.924) than for the females (S[t] = 0.839) (P < .00001). The influence of the operator was not statistically significant on the failure rate (P = .08); however, it was significant on the survival rate (P < .0002). Location in the arch had a significant influence on the failure and survival rates. The worst results were obtained in the upper incisors and the canines, and the best results in the lower premolars. Fifteen percent of the molar tubes failed; their survival rate was equal to 0.833. The failure rate was significantly greater for resin brackets than for metal or ceramic brackets (P = .007). The highest survival rate was obtained with ceramic brackets (P = .0001). This in vivo study showed that bonding brackets and molar tubes with Fuji Ortho LC is compatible with clinical orthodontic practice.

Effects of conventional and high-intensity light-curing on enamel shear bond strength of composite resin and resin-modified glass-ionomer

The purpose of this study was to evaluate the shear bond strengths of a composite resin (Transbond XT; 3M/Unitek, Monrovia, Calif) and a resin-modified glass ionomer (Fuji Ortho LC; GC America Inc, Alsip, Ill) cured with 2 different light-curing units: a conventional visible light unit (Ortholux XT; 3M Dental Products, St Paul, Minn) and a xenon arc light unit (Plasma Arc Curing [PAC] System; American Dental Technologies, Corpus Christi, Texas). One hundred twenty freshly extracted bovine permanent mandibular incisors were randomly divided into 1 of 8 groups; each group consisted of 15 specimens. Two groups (1 group for each type of adhesive) were exposed to the visible light for 20 seconds (Transbond XT) and 40 seconds (Fuji Ortho LC), respectively, and used as control groups. The remaining 6 groups (3 for each adhesive) were cured with the xenon arc light for 2, 5, and 10 seconds. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested in a shear mode on an Instron universal testing machine (Instron Corp, Canton, Mass). For the groups bonded with Transbond XT, no statistically significant differences (P =.868) were found between the shear bond strength of the control group cured with Ortholux XT and those of the groups cured with the PAC System for 2, 5, or 10 seconds. When the shear bond strengths of the groups bonded with Fuji Ortho LC were evaluated, no statistically significant differences (P =.087) were found between the control group that was cured with Ortholux XT and those cured with the PAC System. The bond strength of the composite resin was significantly higher than that of the resin-modified glass ionomer in all the groups tested (P <.0001). The present findings indicate that, compared with visible light-curing, the xenon arc light enables the clinician to significantly reduce the curing time of both bonding agents, without affecting their shear bond strengths. Therefore, xenon arc light sources can be recommended as an advantageous alternative for curing both composite resins and resin-modified glass ionomers.

Effects of two adhesion boosters on the shear bond strength of new and rebonded orthodontic brackets

The purpose of this study was to evaluate the effects of 2 adhesion boosters, Enhance LC (Reliance, Itasca, Ill) and All-Bond 2 (Bisco, Schaumburg, Ill), on the shear bond strength of new and rebonded (previously debonded) brackets. Sixty new and 60 sandblasted rebonded brackets were bonded to 120 extracted human premolars with composite resin and divided equally into 6 groups based on the 2 adhesion boosters used: (1) new brackets/no booster (2) rebonded brackets/no booster (3) new brackets/Enhance (4) rebonded brackets/Enhance (5) new brackets/All-Bond (6) rebonded brackets/All-Bond. Shear bond strength of each sample was tested with an Instron machine (Instron Corp, Canton, Mass). Results show that the new brackets/All-Bond group yielded the highest strength (20.8 +/- 7.5 MPa), followed by the new brackets/Enhance group (18.6 +/- 6.5 MPa), rebond brackets/All-Bond group (17.3 +/- 7.2 MPa), new brackets/no booster group (16.8 +/- 6.3 MPa), rebonded brackets/no booster group (14.2 +/- 7.2 MPa), and rebonded brackets/Enhance group (13.6 +/- 6.7 MPa). No statistically significant difference was found among the 3 groups utilizing new brackets. For groups of rebonded brackets/no booster and rebonded brackets/Enhance, bond strength was significantly lower than groups of 3 new brackets and rebonded brackets/All-Bond. Rebonded brackets/All-Bond group had comparable bond strength to all 3 new brackets groups. It was concluded that in the process of replacing a failed bracket, (1) when new brackets are used, neither All-Bond 2 or Enhance LC improves bond strength significantly, (2) without the use of any adhesion booster, sandblasted rebonded brackets yield significantly less bond strength than new brackets, (3) Enhance LC fails to increase bond strength of sandblasted rebonded brackets, (4) All-Bond 2 significantly increases bond strength of sandblasted rebonded brackets, (5) sandblasted rebonded brackets with All-Bond 2 yield comparable bond strength to new brackets.

Decalcification and bond failure: A comparison of a glass ionomer and a composite resin bonding system in vivo

Decalcification during orthodontic treatment is a serious problem. A glass ionomer agent is now available to bond orthodontic brackets as an alternative to composite resins. This prospective study was a clinical trial to determine if a glass ionomer bonding system (Fuji Ortho LC) decreases the incidence of decalcification without increasing the amount of bonding failures. A prospective clinical trial with 16 patients encompassing a total of 298 teeth was conducted. The 149 control teeth were bonded with a light-cured composite resin (Reliance Light Bond) whereas the 149 experimental teeth were bonded with the light-cured glass ionomer agent. Patients were followed for a period of 12 to 14 months. All teeth were evaluated for breakage (bonding failure rate), and all maxillary anterior teeth (96) were evaluated for decalcification on a graded scale. The glass ionomer failure rate was 24.8%, and was higher than the composite resin failure rate of 7.4% (P <.001). There were more glass ionomer bond failures in 12 of 16 patients (P <.001). Enamel decalcification was similar in the 2 bonding systems.

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.