Evaluation of a new light-cured orthodontic bonding adhesive

Compressive strength and fluoride release profile of a glass ionomer cement reinforced with silver-hydroxyapatite-silica hybrid nanoparticles: An in vitro study

OBJECTIVES

This study aimed to prepare a glass ionomer (GI) cement reinforced with silver-hydroxyapatite-silica (Ag/HA/Si) hybrid nanoparticles and assess its compressive strength and fluoride release profile.

MATERIAL AND METHODS

In this in vitro, experimental study, 60 cylindrical specimens were fabricated with 4mm diameter and 6mm height in 6 groups (n=10) using BracePaste composite, GC Fuji II LC pure RMGI, and RMGI reinforced with 0.1wt%, 0.5wt%, 1wt%, and 2wt% Ag/HA/Si hybrid nanoparticles. The specimens were subjected to compressive force in a universal testing machine to measure their compressive strength (MPa). To assess their fluoride release profile, discs with 3mm diameter and 2mm thickness were fabricated from Fuji II LC pure resin-modified glass ionomer (RMGI), and RMGI with 0.1wt%, 0.5wt%, 1wt%, and 2wt% hybrid nanoparticles, and the concentration of released fluoride was measured by a digital ion-selective electrode. Data were analysed by ANOVA and Scheffe test (alpha=0.05).

RESULTS

The compressive strength was 114.14MPa for BracePaste composite, and 97.14, 97.84, 100.65, 109.5, and 89.33MPa for GI groups with 0%, 0.1%, 0.5%, 1% and 2% hybrid nanoparticles, respectively, with no significant difference among them (P=0.665). Addition of 1% (0.21±0.07μg/mL, P=0.029) and 2% (0.45±0.22μg/mL, P=0.000) hybrid nanoparticles to RMGI significantly increased the amount of released fluoride, compared with the control group (0.09±0.03μg/mL).

CONCLUSIONS

Addition of Ag/HA/Si hybrid nanoparticles to RMGI in the tested concentrations had no significant effect on its compressive strength but addition of 1wt% and 2wt% concentrations of Ag/HA/Si hybrid nanoparticles increased its fluoride release potential.

Comparison of shear bond strength of composite resin, compomer, and resin-modified glass-ionomer cements in primary teeth: An in-vitro study

OBJECTIVE

The contemporary esthetic restorative materials such as composite resin and glass-ionomer cements and their modifications have all been developed keeping in mind the requirements of permanent teeth. There have been plenty of studies that have focused on the characteristics of these materials in relation to permanent teeth with a relative dearth of such studies as regard to the primary teeth. The present study was undertaken to compare and evaluate the shear bond strength of composite resin, compomer, and resin-modified glass-ionomer cements in primary teeth.

METHODS

Thirty non-carious primary molars that were indicated for extraction because of physiological resorption or, for orthodontic reasons, were selected. The selected teeth were randomly allocated to three groups of 10 each for composite, compomer, and resin-modified glass-ionomer cements. The enamel from the occlusal surface of all teeth was removed to expose the superficial dentin and was wet polished with 400 grit sand paper. Composite, compomer, and resin-modified glass-ionomer stubs were bonded on to the occlusal surfaces using a plastic tube as a template. All samples were, then, subjected to thermocycling and evaluation of shear bond strength using the universal testing machine at a cross-head speed of 0.5 mm/min, whereas the results obtained were subjected to statistical analysis. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, IL, USA), whereas one-way analysis of variance (ANOVA) and Tukey's multiple post-hoc procedures were used for statistical analysis. A P < 0.05 was considered statistically significant.

RESULTS

The mean shear bond strength values for Groups I, II, and III were found to be 11.7 ± 3.07 MPa, 7.74 ± 4.16 Mpa, and 4.43 ± 2.08 Mpa, respectively, whereas one-way ANOVA and Tukey's multiple post-hoc procedures indicated that there were remarkable differences among the three groups with the results being statistically significant (P < 0.05).

CONCLUSIONS

Composite resin showed the highest shear bond strength in relation to primary dentin when compared to compomer and resin-modified glass-ionomer cements.

Is An Orthodontic Hydrophilic Composite Resistant to Contamination and pH Cycling? In vitro Results

Objective:

To evaluate the adhesive strength of a hydrophilic composite submitted to contamination and pH cycling, compared to a conventional composite.

Materials and Methods:

Seventy-two bovine incisors were prepared and randomly divided into 6 groups (n=12), bonded with Hydrophilic Composite (HC)(Transbond Plus Color Change) or with Conventional Composite (CC)(Transbond XT; control), with or without contamination and pH cycling as follows: G1-HC, with contamination, with pH cycling; G2-HC, with contamination, without pH cycling; G3-HC, without contamination, with pH cycling; G4-HC, without contamination, without pH cycling; G5-CC, without contamination, with pH cycling; G6-CC, without contamination, without pH cycling. Contamination in G1 and G2 consisted of fresh saliva applied after the self-etching primer for 5min before bonding with HC. After bonding, G1, G3, and G5 were submitted to pH cycling, immersed in the demineralizing solution for 22h and for 2h in remineralizing artificial saliva, repeated for 15 days. G2, G4, and G6 were kept in deionized water. The shear bond strength was tested using a load cell of 100N and the Adhesive Remnant Index (ARI) was assessed. Intergroup comparison was performed with one-way ANOVA, Tukey, and chi-square tests.

Results:

There was a statistically significant difference in G1, G2, and G3 in relation to G6. The highest rate of adhesive failure between the resin/bracket interface occurred with the HC, while CC failed more at the resin/tooth interface.

Conclusion:

Contamination and pH cycling did not decrease the shear bond strength of brackets bonded with the hydrophilic composite. However, the adhesive strength of the conventional composite was higher.

Shear Bond Strength of Molar Tubes to Enamel Using an Orthodontic Resin-Modified Glass Ionomer Cement Modified with Amorphous Calcium Phosphate

Objectives:

This study aimed to assess the shear bond strength (SBS) of molar tubes to the enamel surface of molar teeth using a resin-modified glass ionomer (RMGI) cement modified with amorphous calcium phosphate (ACP).

Materials and Methods:

In this in-vitro study, 60 extracted human third molars were randomly divided into four groups for bonding of molar tubes to the enamel surface. Fuji Ortho LC and Fuji Ortho LC modified with ACP (1.55 wt%) were used in groups 1 and 2, respectively. In group 3, the enamel surface was sandblasted, and bonding was then performed using Fuji Ortho LC glass ionomer modified with ACP. In group 4, molar tubes were conventionally bonded using Transbond XT composite. The SBS was measured using a universal testing machine.

Results:

The mean SBS of groups 1 to 4 was 10.22, 6.88, 9.4, and 13.68 MPa, respectively. Only the SBS of group 1 was not significantly different from that of groups 3 and 4 (P>0.05). Comparison of adhesive remnant index (ARI) scores of the groups revealed significant differences only between groups 1 and 4 (P<0.001) and between groups 1 and 2 (P=0.002).

Conclusion:

The results revealed that the addition of ACP to Fuji Ortho LC significantly decreased the SBS of molar tubes bonded to enamel compared to the conventional resin bonding system. Sandblasting of the enamel surface significantly increased the bond strength. Fuji Ortho LC modified with ACP is recommended for bonding of molar tubes to posterior teeth considering its cariostatic property.

Adhesive luting of orthodontic devices to silica-based ceramic crowns-comparison of shear bond strength and surface properties

OBJECTIVES

The aim of this study was to analyse the impact of different clinical conditioning approaches and an ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based experimental primer for intraoral luting of buccal tubes on silica-based ceramic surfaces.

MATERIALS AND METHODS

A total of 60 leucite-reinforced glass ceramic molar crowns were conditioned using different methods (n = 10): I-roughening, hydrofluoric acid, silane; II-roughening, silane; III-roughening, experimental coupling agent; IV-experimental coupling agent; V-roughening; VI-no treatment. A buccal tube was adhesively luted to the ceramic surface. Subsequently, water storage, thermocycling and chewing simulation were carried out. The shear bond strength (SBS) was determined, and changes in the surface were assessed.

RESULTS

All tubes of the control group (group VI) debonded after incubation. The conditioning methods using coupling agents revealed mean values for SBS of 61.56 MPa (group I), 45.53 MPa (group III), 41.65 MPa (group II), and 23.14 MPa (group IV). In groups I-III, both composite residues and cracks/tear-outs were detected.

CONCLUSIONS

The conditioning of silicate ceramic surfaces with a suitable coupling agent system appears to allow sufficient adhesive luting of buccal tubes. The intraoral luting of fixed appliance elements on silicate ceramic surfaces using an ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based ceramic primer can withstand orthodontic forces.

CLINICAL RELEVANCE

Ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based ceramic primers revealed promising results for the intraoral adhesive luting of orthodontic devices to silica-based ceramic crowns.

A comparative assessment of orthodontic treatment outcomes using the quantitative light-induced fluorescence (QLF) method between direct bonding and indirect bonding techniques in adolescents: a single-centre, single-blind randomized controlled trial

Introduction

The aim of this two-arm parallel trial was to evaluate enamel demineralization in fixed orthodontic treatment using an indirect bonding technique in comparison to a direct bonding technique by the quantitative light-induced fluorescence (QLF) method.

Design, settings and participants

Fifty-six patients who needed fixed orthodontic treatment were randomly separated into either the direct bonding group or the indirect bonding group. The presence and extent of lesions on the buccal surfaces of all teeth, except the molar teeth, were assessed. The percentage of fluorescence loss (ΔF and ΔFmax), the degree of demineralization (ΔQ) and lesion area (WS area) were determined using the system’s software. The data were analysed with the Wilcoxon signed-rank and Mann–Whitney U-tests (P &lt; 0.05).

Interventions

Treatment with a direct bonding or an indirect bonding technique.

Results

This study was completed with 25 patients in the indirect bonding group (12 females, 13 males; mean age: 15.42 ± 1.71 years) and 26 patients in the direct bonding group (12 females, 14 males; mean age: 14.73 ± 1.65 years). In the indirect bonding technique, a few teeth (especially mandibular left canine: 50.45 ± 93.48; 95% confidence interval: −12.35 and 113.26) were found to develop significant white spot lesion (WSL) formation (P &lt; 0.05). However, the number of teeth with demineralization was higher in the direct bonding group (P &lt; 0.05).

Conclusion

The bonding procedures used in the indirect bonding technique contribute to reducing the degree of WSL formation. Further, the use of flowable composite adhesives in this bonding process is more effective at reducing the appearance of WSLs than in cases where conventional composite adhesives are used.

Limitations

The limitation of our trial may be the small sample size and the short follow-up time for the patients.

Harms

No harms were detected during the study.

Protocol

The protocol was not published before trial commencement.

Registration

This trial was registered post hoc at ‘Clinical Trials’ (http://www.clinicaltrials.gov), registration number (ID): NCT03738839.

In vitro Evaluation of Shear Bond Strength of Orthodontic Brackets Bonded with Different Adhesives

Background:

There is necessary of dry operating field for bonding of orthodontic brackets. The presence of moisture can alter the bond strength. Hence, the aim of the present study was to evaluate the shear bond strength of orthodontic brackets with different adhesives.

Materials and Methods:

In this in vitro study, a total of 100 orthodontically extracted premolars with sound crown structure were divided into 4 equal groups of different primers. Bonding on the buccal surface of all teeth was done after acid etching with upper premolar brackets using different primers followed by light curing. Shear bond strength was evaluated with or without salivary contamination with both adhesives. A shear force for deboning the bracket was done with universal testing machine. The debonded specimens were examined at ×10 magnification to check site of bond failure and remaining adhesive on tooth using adhesive remnant index (ARI). The obtained data were statistically evaluated using SPSS 20 for Windows (SPSS Inc., Chicago, IL, USA) using ANOVA, Kolmogorov–Smirnov, and Levene's test at the statistical significance of P < 0.05.

Results:

Transbond Plus showed higher shear bond strength of 8.92 MPa under dry and 5.65 MPa with saliva contamination over Transbond XT of 7.24 MPa under dry and 2.43 MPa with saliva contamination, respectively. Higher ARI score was found without contamination in both adhesives.

Conclusion:

Transbond Plus hydrophilic resin had good shear bond strength under both dry and contamination condition compared to hydrophobic Transbond XT resin material.

Comparing orthodontic bond failures of light-cured composite resin with chemical-cured composite resin: A 12-month clinical trial

INTRODUCTION

In this clinical trial, we evaluated and compared bond failure rates of light-cured composite resin vs chemical-cured composite resin for 12 months.

METHODS

Twenty-two subjects (356 stainless steel brackets) were included in this study, and a split-mouth design was used to randomly allocate diagonally opposite quadrants to either chemical-cured (178 brackets) or light-cured (178 brackets) composite resin; the brackets came from the same manufacturer. The survival and failure rates of the brackets were evaluated by the mode of polymerization. The overall bracket survival rates were estimated using the Kaplan-Meier product limit estimate.

RESULTS

There were no significant differences in the bond failure rates between the chemical-cured and the light-cured composites (P = 0.52). Bond failures were greater in posterior teeth (6.7%) than in anterior teeth (1.2%). The highest failure rate was observed in the second premolars (7.7%).

CONCLUSIONS

The overall failure rate of brackets with the 2 bonding systems was 2.8%, which is acceptable for clinical use. The polymerization mode did not influence the bracket survival rate significantly.

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.

Effect of Ti:sapphire laser on shear bond strength of orthodontic brackets to ceramic surfaces

BACKGROUND AND OBJECTIVES

With increasing demand for orthodontic treatments in adults, orthodontists continue to debate the optimal way to prepare ceramic surfaces for bonding. This study evaluated the effects of a Ti:sapphire laser on the shear bond strength (SBS) of orthodontic brackets bonded to two ceramic surfaces (feldspathic and IPS Empress e-Max) and the results were compared with those using two other lasers (Er:YAG and Nd:YAG) and 'conventional' techniques, i.e., sandblasting (50 µm) and hydrofluoric (HF) acid.

MATERIALS AND METHODS

In total, 150 ceramic discs were prepared and divided into two groups. In each group, the following five subgroups were prepared: Ti:sapphire laser, Nd:YAG laser, Er:YAG laser, sandblasting, and HF acid. Mandibular incisor brackets were bonded using a light-cured adhesive. The samples were stored in distilled water for 24 hours at 37°C and then thermocycled. Extra samples were prepared and examined using scanning electron microscopy (SEM). SBS testing was performed and failure modes were classified. ANOVA and Tukey's HSD tests were used to compare SBS among the five subgroups (P < 0.05).

RESULTS

Feldspathic and IPS Empress e-Max ceramics had similar SBS values. The Ti:sapphire femtosecond laser (16.76 ± 1.37 MPa) produced the highest mean bond strength, followed by sandblasting (12.79 ± 1.42 MPa) and HF acid (11.28 ± 1.26 MPa). The Er:YAG (5.43 ± 1.21 MPa) and Nd:YAG laser (5.36 ± 1.04 MPa) groups were similar and had the lowest SBS values. More homogeneous and regular surfaces were observed in the ablation pattern with the Ti:sapphire laser than with the other treatments by SEM analysis.

CONCLUSIONS

Within the limitations of this in vitro study, Ti:sapphire laser- treated surfaces had the highest SBS values. Therefore, this technique may be useful for the pretreatment of ceramic surfaces as an alternative to 'conventional' techniques.

Comparison of shear bond strength of orthodontics brackets on composite resin restorations with different surface treatments

INTRODUCTION

Orthodontic patients frequently present composite resin restorations, however there are few studies that evaluate the best way for orthodontic bonding in this situation.

OBJECTIVE

The objective of this work was to evaluate the bond strength of orthodontic brackets in resin restorations with surface treatment.

METHODS

Fifty one bovine lower incisors were randomly divided into three groups. On the control group (CG) the brackets were bonded to dental enamel; on experimental groups, brackets were bonded to resin restoration with diamond drill treatment (EGT) and with no treatment (EGN). The teeth were placed in PVC tubes with self-etching acrylic resin. The shear test was performed in EMIC universal testing machine. The groups were submitted to ANOVA analysis of variance with Tukey post test to verify the statistical difference between groups (α = 0.05).

RESULTS

CG (6.62 MPa) and EGT (6.82 MPa) groups presented similar results, while EGN (5.07 MPa) obtained statistically lower results (p < 0.05).

CONCLUSIONS

Therefore, it is concluded that the best technique for bonding orthodontic brackets on composite resin restorations is the performance of surface detritions.

Are the low-shrinking composites suitable for orthodontic bracket bonding?

Purpose:

To evaluate the shear bond strength (SBS), adhesive remnant index (ARI), and microleakage of low-shrinking and conventional composites used as an orthodontic bracket bonding adhesive.

Materials and Methods:

A hundred twenty non-caries human premolars, extracted for orthodontic purposes, were used in this study. Sixty of them were separated into two groups. Brackets were bonded to the teeth in the test group with Silorane (3M-Espe) and control group with Transbond-XT (3M-Unitek). SBS values of these brackets were recorded in MPa using a universal testing machine. ARI scores were determined after the failure of brackets. The remaining 60 teeth were divided into two groups and microleakage was evaluated by the dye penetration method. Statistical analyses were performed by Wilcoxon, Pearson Chi-square, and Mann–Whitney U tests at P < 0.05 level.

Results:

The mean SBS for Transbond XT was significantly greater than low-shrinking composite (P < 0.001). Significant differences (χ² =29.60, P < 0.001) were present between the two groups for the ARI scores. Microleakage values were lower in low-shrinking composite than in the control group, and this difference was found to be statistically significant (P < 0.001).

Conclusions:

Although low-shrinking composite produced insufficient SBS and ARI scores, microleakage values were lower in low-shrinking composite than in the control group on the etched enamel surfaces, when used as a bracket bonding composite.

A comparative evaluation of the retention of metallic brackets bonded with resin-modified glass ionomer cement under different enamel preparations: A pilot study

Introduction:

For orthodontists, the ideal bonding material should be less moisture-sensitive and should release fluoride, thereby reducing unfavorable iatrogenic decalcification. Resin-Modified Glass Ionomer Cements (RMGICs), due to their ability to bond in the presence of saliva and blood can be a very good bonding agent for orthodontic attachments especially in the areas of mouth, which are difficult to access. Moreover, their fluoride releasing property makes them an ideal bonding agent for patients with poor oral hygiene. However, their immediate bond strength is said to be too low to immediately ligate the initial wire, which could increase the total number of appointments. The effect of sandblasting and the use of sodium hypochlorite (NaOCL) on the immediate bond failure of RMGIC clinically have not been reported in the literature until the date. This investigation intended to assess the effect of sandblasting (of the bracket base and enamel) and NaOCL on the rate of bond failure (with immediate ligation at 30 min) of Fuji Ortho LC and its comparison with that of conventional light cured composite resin over a period of 1 year.

Materials and Methods:

400 sample teeth were further divided into 4 groups of 100 each and bonded as follows: (1) Group 1: Normal metallic brackets bonded with Fuji Ortho LC. (2) Group 2: Sandblasted bracket base and enamel surface, brackets bonded with Fuji Ortho LC. (3) Group 3: Deproteinized enamel surface using sodium hypochlorite and brackets bonded with Fuji Ortho LC. (4) Group 4: Normal metallic bracket bonded with Transbond XT after etching enamel with 37% phosphoric acid. This group served as control group.

Results and Conclusion:

Results showed that sandblasting the bracket base and enamel, can significantly reduce the bond failure rate of RMGIC.

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.

Effect of light-cure initiation time on polymerization efficiency and orthodontic bond strength with a resin-modified glass-ionomer

OBJECTIVES

The polymerization and acid-base reactions in resin-modified glass-ionomers (RMGI) are thought to compete with and inhibit one another. To examine the effect of visible light-cure (VLC) delay on the polymerization efficiency and orthodontic bond strength of a dual-cured RMGI.

SETTING AND SAMPLE POPULATION

The Orthodontics Graduate Program at Marquette University. An in vitro study utilizing 72 freshly extracted human bicuspid teeth.

MATERIALS AND METHODS

A RMGI light-cured immediately, 2.5, 5, or 10 min after mixing comprised the experimental groups. Isothermal and dynamic temperature scan differential scanning calorimetry (DSC) analysis of the RMGI was performed to determine extents of VLC polymerization and acid-base reaction exotherms. Human premolars (n = 18/group) were bonded with the RMGI. Shear bond strength and adhesive remnant index (ARI) scores were determined.

RESULTS

Differential scanning calorimetry results showed the 10-min-delay RMGI group experienced significantly (p < 0.05) lower VLC polymerization compared with the other groups. Acid-base reaction exotherms were undetected in all groups except the 10-min delay group. No significant differences (p > 0.05) were noted among the groups for mean shear bond strength. A chi-square test showed no significant difference (p = 0.428) in ARI scores between groups.

CONCLUSIONS

Delay in light-curing may reduce polymerization efficiency and alter the structure of the RMGI, but orthodontic shear bond strength does not appear to be compromised.

Resistência ao cisalhamento da colagem com compósitos utilizando potencializador de adesão

OBJETIVO: avaliar a resistência ao cisalhamento dos compósitos Transbond XT e Concise Ortodôntico utilizando o potencializador de adesão Ortho Primer. MÉTODOS: a amostra consistiu de 90 incisivos bovinos divididos em seis grupos (n=15). Todos os dentes receberam profilaxia com pedra-pomes e condicionamento do esmalte com ácido fosfórico. No Grupo I, utilizou-se Transbond XT de maneira convencional. O Grupo II foi semelhante ao I, porém, aplicou-se o Ortho Primer ao invés do XT Primer. No Grupo III, após condicionamento, o esmalte foi contaminado com saliva, aplicou-se o Ortho Primer e colagem com Transbond XT. No Grupo IV, utilizou-se o Concise Ortodôntico de maneira convencional. O Grupo V foi semelhante ao IV, porém, utilizou-se o Ortho Primer ao invés da resina fluida. No Grupo VI, após condicionamento, o esmalte foi contaminado com saliva, aplicou-se o Ortho Primer e colagem com Concise. Os corpos de prova foram armazenados em água destilada em estufa a 37ºC por 24h e submetidos ao ensaio de resistência ao cisalhamento. Os dados foram submetidos à ANOVA e ao teste de Tukey (5%). RESULTADOS: a resistência da colagem no Grupo IV foi estatisticamente superior à dos Grupos II, III e VI (p<0,05). Entre os Grupos I, IV e V; e entre os Grupos I, II, III e VI não foram encontradas diferenças estatísticas significativas (p>0,05). O Transbond XT e o Concise utilizados convencionalmente obtiveram os maiores valores adesivos. O Ortho Primer em esmalte seco atuou efetivamente como agente de união dos compósitos avaliados. Em esmalte contaminado, a colagem com Concise obteve baixa resistência adesiva.

Avaliação da resistência ao cisalhamento de dois compósitos colados em superfície condicionada com primer autocondicionante

OBJETIVO: o objetivo desse estudo foi avaliar a resistência ao cisalhamento e o índice de remanescente de adesivo (IRA) dos compósitos Eagle Bond e Orthobond em superfície de esmalte condicionada com Transbond Plus Self-Etching Primer. MÉTODOS: foram utilizados 75 incisivos inferiores permanentes bovinos divididos em cinco grupos (n=15). Nos grupos 1, 2 e 4, as colagens foram realizadas com Transbond XT, Orthobond e Eagle Bond, respectivamente, seguindo as recomendações dos fabricantes. Nos grupos 3 e 4, antes da colagem com o Orthobond e o Eagle Bond, respectivamente, a superfície dentária foi condicionada com o ácido-primer Transbond Plus Self-Etching Primer. Após a colagem, realizou-se o ensaio de cisalhamento de toda amostra à velocidade de 0,5mm/min em máquina Instron de ensaios mecânicos. RESULTADOS:os resultados (em MPa) mostraram não haver diferenças estatisticamente significativas entre os grupos 1, 2, 3 e 5 (p>0,05). Entretanto, esses grupos foram estatisticamente superiores ao grupo 4 (p<0,05). Os resultados do IRA (Índice de Remanescente de Adesivo) evidenciaram maior número de fraturas na interface braquete/compósito nos grupos 1, 2, 3 e 5.

Effect of short curing times with a high-intensity light-emitting diode or high-power halogen on shear bond strength of metal brackets before and after thermocycling

OBJECTIVE

To test the hypothesis that short curing times using a high-intensity light-emitting diode (LED) or high-power halogen are not associated with compromised shear bond strength (SBS) of metal brackets before and after thermocycling.

MATERIALS AND METHODS

Two hundred forty extracted human premolar teeth were divided into six groups of 40 each. Metal brackets were bonded using a light-cured composite (Transbond XT). In group 1 a conventional halogen light (Hilux) was used for 40 seconds. In groups 2, 3, and 4 a high-power halogen light (Swiss Master) was used for 2, 3, and 6 seconds, respectively. In groups 5 and 6 a high-intensity LED (Bluephase) was used for 10 and 20 seconds, respectively. After bonding, half of the specimens in each group were thermocycled, and all specimens were tested for SBS. After debonding, the bracket bases and the enamel surfaces were scored according to the Adhesive Remnant Index.

RESULTS

Two-way analysis of variance detected significant differences in SBS values with respect to curing method (type of light-curing unit and curing time) (P  =  .0001) and thermocycling (P  =  .01). Tukey post hoc analysis showed that with or without thermocycling the mean SBS values of groups 1, 4, 5, and 6 were not significantly different, whereas group 2 showed the lowest SBS values. The predominant failure site for groups 2 and 3 was between the bracket and the adhesive and for groups 4, 5, 6 it was at the tooth/adhesive interface.

CONCLUSION

Curing time can be reduced to 6 seconds with high-power halogen light and to 10 seconds with high-intensity LED without compromising in vitro SBS of metal brackets.

KommonBase for precise direct bonding of lingual orthodontic brackets

On account of the morphological variations of lingual dental surfaces, indirect bonding systems have been used for bonding lingual orthodontic brackets. Improvements in bracket seating and bonding systems have enabled the development of KommonBase, a precise direct bonding system. KommonBase is characterized by a large bonding base, which can achieve a good bracket fit and precise bracket positioning while also enhancing bond strength. Furthermore, transfer trays are not required because of its self-positioning shape. KommonBase offers an advantageous alternative to conventional indirect bonding systems for the bonding of lingual orthodontic brackets.

Influência de variáveis metodológicas na resistência de união ao cisalhamento

OBJETIVO: avaliar a influência de diferentes variáveis metodológicas sobre a resistência de união ao cisalhamento em estudos in vitro. MÉTODOS: foram utilizados 105 incisivos permanentes bovinos, seccionados ao nível do colo dentário. A porção coronária foi inclusa em tubos de PVC, com resina acrílica autopolimerizável, e com face vestibular voltada para cima. Todos os corpos de prova foram preparados para a colagem com profilaxia e condicionamento ácido na região central das coroas, onde foram posicionados braquetes Morelli® de incisivos centrais superiores, com resina Concise® Ortodôntico (3M/Unitek). Foram determinados três grupos de acordo com a variável estudada: (Grupo 1) - meio de armazenamento dos dentes, previamente à inclusão e à colagem, com solução de timol 0,1% (a), água destilada (b) e congelamento (c); (Grupo 2) - velocidade da célula de carga da máquina de ensaio de 0,5 (a), 1,0 (b) e 2,0mm/min (c) e (Grupo 3) - diferentes marcas comerciais de ácidos fosfóricos a 37%, 3M/Unitek (a), AcidGel (b) e Attack Tek (c). Os corpos de prova foram submetidos ao ensaio mecânico de resistência ao cisalhamento através da máquina Emic DL2000®. Os dados foram analisados estatisticamente por meio do Teste t Student para amostras independentes. RESULTADOS: os resultados demonstraram que no Grupo 1 o subgrupo de congelamento apresentou maiores valores em relação aos outros dois subgrupos, porém sem diferença estatisticamente significativa (p > 0,05). No Grupo 2, a força no momento da ruptura foi menor à medida que era aumentada a velocidade da célula de carga, porém sem diferença significativa entre os subgrupos. No Grupo 3, o ácido da 3M/Unitek apresentou a maior média em MPa, no entanto, também sem diferença significativa entre os subgrupos. CONCLUSÕES: conclui-se, portanto, que as variáveis analisadas neste trabalho não apresentaram influência suficiente para determinação de diferenças estatisticamente significativas entre os resultados.

The effect of moisture on the shear bond strength of gold alloy rods bonded to enamel with a self-adhesive and a hydrophobic resin cement

The aim of this in vitro study was to investigate the influence of enamel moisture on the shear bond strength (SBS) of a hydrophobic resin cement, Maximum Cure (MC), and a self-adhesive resin cement, Multilink Sprint (MLS), after etching of the enamel. Forty cylindrical gold alloy rods were used to simulate the Incognito lingual bracket system. They were bonded to the enamel of 40 human teeth embedded in self-cured acrylic resin. Twenty were bonded with MC (10 on dry and 10 on wet enamel) and 20 with MLS (10 on dry and 10 on wet enamel). The SBS of MC and MLS was determined in a universal testing machine and the site of bond failure was defined by the adhesive remnant index (ARI). A Kruskal-Wallis test was performed followed by Games-Howell post hoc pairwise comparison tests on the SBS results (P < 0.05) and a chi-square test was used for the analysis of ARI scores (P < 0.05). On dry enamel, no significant differences between MC (58 +/- 5 MPa) and MLS (64 +/- 13 MPa) were noted. On wet enamel, the adherence of MC (6 +/- 8 MPa) and MLS (37 +/- 13 MPa) significantly decreased but to a lesser extent for MLS. The ARI scores corroborated these results. In conclusion, MC did not tolerate moisture. MLS was also affected but maintained sufficient adherence.

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.

In vitro release of phosphoric acid ester from self-etching primer

Self-etching primers have simplified the process of direct bonding of dental resins, by eliminating the rinsing step after etching in conventional bonding, for example. Although it is generally assumed that all of the applied self-etching primer is incorporated into the resin, the possibility that a substantial amount remains free and extractable into a person's saliva has not been investigated. The aim of the present study was to examine this issue by bonding brackets to extracted teeth with self-etching primers under controlled conditions and determining the proportion of the applied phosphoric acid ester that is subsequently extractable by high-performance liquid chromatography. Approximately half of the applied acid ester was extractable and thus not integrated into the polymeric network following standard light curing. This was reduced to 40% when the curing time was doubled. Acid ester leaching was a rapid process that was essentially completed within an hour.

Use of flowable composites for orthodontic bracket bonding

OBJECTIVE

To test the bonding characteristics of four flowable composites for orthodontic bracket bonding.

MATERIALS AND METHODS

Metal brackets were bonded to acid-etched human enamel using four flowable composites (Grandio Flow, GF; UniFil Flow, UF; UniFil LoFlo Plus, UL; and DenFil Flow, DF), an orthodontic bonding system (Transbond XT, TX), and a restorative composite (Filtek Z250, FZ). After 24 hours of storage in water at 37 degrees C, a shear bond strength (SBS) test was performed. After debonding, the adhesive remnant index (ARI) was assessed. In addition, the flow and flexural strength of the materials were examined.

RESULTS

The SBS for the flowable composites ranged between 7.2 and 8.3 MPa, and TX showed a significantly higher value (mean 10.9 MPa). The flowable composites also demonstrated a significantly superior flowability, yet inferior flexural strength (except for DF) than TX and FZ. Two flowable composites (GF and UL) produced significantly higher ARI scores than TX and FZ, which represented a larger resin remnant on the enamel surfaces after debonding.

CONCLUSION

When considering the SBS and ARI scores obtained in this study, flowable composites with no intermediate bonding resin could be conveniently applied for orthodontic bracket bonding.

Influence of saliva contamination on zirconia ceramic bonding

OBJECTIVES

The purpose of this study was to investigate the influence of saliva contamination and cleaning methods on adhesive bonding to dental zirconia ceramic with a phosphate-monomer-containing luting resin.

METHODS

After saliva immersion, airborne-particle abraded ceramic specimens were cleaned with water rinsing, with isopropanol, with phosphoric acid gel, or with additional airborne-particle abrasion. Airborne-particle abraded specimens without contamination were used as the control group. Chemical analysis of the ceramic surfaces of all groups was done using X-ray photoelectron spectroscopy (XPS). The influence of contamination and cleaning methods on ceramic bond durability was examined by tensile bond strength (TBS) testing after 3 days or 150 days water storage with 37,500 thermal cycles.

RESULTS

After saliva contamination XPS revealed an organic coating which was not removed completely with water rinsing, with isopropanol, or with phosphoric acid. Using TBS testing a strong influence of contamination and cleaning methods on resin bond strength and its durability was found.

SIGNIFICANCE

Saliva contamination significantly affected resin bonds to zirconia ceramic and its durability. Airborne-particle abrasion was the most effective cleaning method.

Avaliação da força de tração em braquetes colados pela técnica indireta com diferentes sistemas de adesão

OBJETIVO: o objetivo do presente estudo foi avaliar a resistência à tração de braquetes ortodônticos colados pela técnica indireta e pela técnica direta convencional. METODOLOGIA: foram utilizados 50 pré-molares humanos íntegros, recém-extraídos por motivos ortodônticos. Esses dentes foram divididos em 5 grupos, nos quais foram colados braquetes ortodônticos metálicos (Abzil-Brasil) com as resinas compostas ortodônticas Concise (3M-Unitek-EUA) e Transbond XT (3M-Unitek-EUA) - utilizadas em ambas as técnicas, direta e indireta - e Transbond Sondhi (3M-Unitek-EUA) - desenvolvida exclusivamente para a técnica indireta. O grupo I (controle I) foi objeto de colagem direta com Transbond XT; no grupo II (controle II) procedeu-se à colagem direta com Concise o grupo III recebeu colagem indireta com Concise; o grupo IV foi submetido à colagem indireta com Transbond XT e no grupo V foi realizada colagem indireta com Transbond Sondhi. Na técnica direta, o braquete foi colado diretamente sobre o esmalte após condicionamento ácido e aplicação de adesivo. Na técnica indireta, os braquetes foram colados primeiramente sobre modelo de gesso e depois transferidos para o dente, com o auxílio de moldeira individualizada. Os corpos-de-prova foram submetidos a testes de tração (Instron 4400) e os resultados foram objeto de testes estatísticos de análise de variância e de Tukey a 1%. RESULTADOS: os grupos III e V revelaram resultados significantemente menores que os dos dois grupos controles. CONCLUSÃO: a força obtida na colagem indireta com a resina Transbond XT não difere da força obtida na colagem direta com as resinas Concise e Transbond XT.

Xeno III self-etching adhesive in orthodontic bonding: the next generation

INTRODUCTION

The newer single-step self-etching adhesives that etch, prime, and apply the resin bonding agent simultaneously without rinsing have been increasing in popularity in orthodontic bonding. The purpose of this study was to compare the bond strengths and to evaluate the debonding site (with the adhesive remnant index), when a conventional acid-etch conditioner and a self-etching adhesive system (Xeno III, Dentsply DeTrey GmbH, Konstanz, Germany) were used with either a composite resin adhesive (Transbond XT, 3M Unitek, Monrovia, Calif) or a resin-modified glass ionomer cement (Fuji Ortho LC, GC Corp, Tokyo, Japan).

METHODS

One hundred twenty extracted human premolars were mounted in acrylic resin and randomly assigned to 6 groups of 20 teeth each. Shear-peel bond strength testing was performed after thermocycling (5 degrees C-55 degrees C for 500 times) with a Zwick 1440 compression machine (Zwick, Ulm, Germany).

RESULTS

The results showed that the bond strengths achieved with Xeno III were comparable with the traditional methods of either 37% phosphoric acid or 10% polyacrylic acid for both Transbond XT and Fuji Ortho LC. Adhesive remnant index scores showed less adhesive remaining on the tooth surface in the Xeno III/Transbond XT adhesive only (no primer) group.

CONCLUSIONS

Xeno III can be used to bond orthodontic brackets with the adhesives in this study.

Influence of contamination on bonding to zirconia ceramic

The purpose of this study was to investigate the influences of contaminations and cleaning methods on bonding to dental zirconia ceramic. After saliva immersion and using silicone disclosing agent, airborne-particle abraded ceramic specimens were cleaned with isopropanol (AL), acetone (AC), 37% phosphoric acid (PA), additional airborne-particle abrasion (AA), or only with water rinsing (SS). Airborne-particle abraded specimens without contaminations (CL) were used as control group. For chemical analysis specimens of all groups were examined with X-ray photoelectron spectroscopy (XPS). Plexiglas tubes filled with composite resin were bonded to ceramic specimens using a phosphate-monomer containing composite luting resin. After 3-day water storage, tensile bond strengths (TBS) were tested. XPS analysis of group SS showed the presence of saliva and silicone (Si) contamination on the surface. The ratios of carbon/zirconium and oxygen/zirconium for groups PA and AA were comparable to those ratios obtained for group CL, indicating the removal of the organic saliva contamination. Airborne-particle abrasion and acetone completely removed Si contamination from ceramic surfaces. Isopropanol had little cleaning effect on the two contaminants. TBS (median +/- standard deviation) in MPa of the groups SS (11.6 +/- 3.1), AL (10.0 +/- 2.9), and AC (13.0 +/- 2.8) were statistically lower than those of groups PA (33.6 +/- 5.5), AA (40.1 +/- 3.6), and CL (47.0 +/- 8.1) (p < 0.001), while no differences were found in TBS between groups AA and CL (p > 0.5). Contamination significantly reduced bond strengths to zirconia ceramic. Airborne-particle abrasion was the most effective cleaning method.

The relationship between craniofacial structures and the nose in Anatolian Turkish adults: a cephalometric evaluation

INTRODUCTION

The aim of this study was to evaluate the relationship between the facial skeletal and the nasal profile in Anatolian Turkish adults. This prospective study was conducted at Gazi University, Faculties of Dentistry and Medicine, in Ankara, Turkey.

METHODS

The sample included 262 Turkish adults (167 women, 95 men), aged 18 to 30 years. Fifteen facial skeletal parameters and 12 nasal parameters (10 soft tissue and 2 nasal skeletal) were measured on lateral cephalograms. Analysis of variance, Duncan test, and Pearson correlation analysis were used for statistical analysis.

RESULTS

The anteroposterior and vertical classifications were found to be significant with analysis of variance in certain parameters such as nasolabial angle (P < .05), nasomental angle (P < .001), and soft-tissue facial convexity (P < .001). Sex was also found to be significant for nasal length (P < .001), nasal depths (P < .05, P < .001), and hump (P < .01), in addition to soft-tissue facial convexity (P < .01). The results also showed correlations between the skeletal and nasal parameters. Facial heights, lengths, and the anteroposterior/vertical position of the maxilla and mandible were found to be correlated to nasal length and form.

CONCLUSIONS

Nasal length, prominence, and form are associated with height and length of the maxilla and the mandible. Posterior-inferior development of the face results in a convex nasal profile, whereas anterior development produces a straight or concave nasal profile.

Shear/peel bond strength of orthodontic attachments to moist and dry enamel

INTRODUCTION

The purpose of this study was to evaluate the in-vitro shear-peel bond strength of orthodontic attachments bonded to moist and dry enamel surfaces with orthodontic resin.

METHODS

Two stainless-steel mesh-based buttons were bonded to pumiced and etched enamel of each of 60 human molars mounted in cylindrical molds with Transbond XT (3M/Unitek, St Paul, Minn) (control), Smartbond (Gestenco International, Goteborg, Sweden), or Assure (Reliance Orthodontic Products, Itasca, Ill) according to each manufacturer's instructions. Half of the teeth were bonded under dry conditions, and half were given a thick layer of whole, unstimulated, fresh human saliva just before bonding. The teeth were stored in distilled deionized water at 37 degrees C. The shear-peel bond strength of 1 button on each tooth was evaluated in a testing device (Zwick, Ulm, Germany) at 24 hours; the remaining button on each tooth was evaluated at 6 months.

RESULTS

Statistically significant differences (P < .05) were evident in button adhesion to the tooth surface between moisture variations for Transbond XT, but not for Assure and Smartbond. Superior bond strengths were obtained for Transbond XT on dry enamel; the bond strength of Assure to saliva-contaminated enamel was better than that of the other materials.

CONCLUSIONS

Bonding to moist and dry enamel appears to be material-specific. Adequate in-vitro bonding to moist, saliva-contaminated enamel is possible with certain bonding materials.

Effect of an antioxidizing agent on the shear bond strength of brackets bonded to bleached human enamel

INTRODUCTION

The purpose of this study was to investigate the effect of antioxidant treatment and delayed bonding on the shear bond strength of metal brackets bonded with composite resin to human enamel after bleaching with carbamide peroxide (CP).

METHODS

Eighty recently extracted premolars were divided into an experimental group (n = 60), which was bleached with 10% CP, and a control group (n = 20), which was not bleached. The experimental group was further divided into 3 groups. Specimens in group 1 (n = 20) were bonded immediately after bleaching; specimens in group 2 (n = 20) were bleached, then treated with 10% sodium ascorbate, an antioxidant agent, and then bonded; group 3 specimens (n = 20) were bleached, then immersed in artificial saliva and held for 1 week before bonding. The specimens were debonded, and the enamel surfaces and bracket bases were examined with a stereomicroscope. The adhesive remnant index was used to assess the amount of resin left on the enamel surfaces after debonding. The shear bond strength data were subjected to 1-way analysis of variance. Multiple comparisons were performed with the Bonferroni test. The level of significance was established at P < .05 for all statistical tests.

RESULTS

Shear bond strength of brackets bonded immediately after bleaching with 10% CP was significantly lower than that of brackets bonded to unbleached enamel (P < .05). No statistically significant differences in shear bond strength were noted when the antioxidant-treated and delayed bonding groups were compared with the control group (P > .05).

CONCLUSIONS

Bleaching with 10% CP immediately before bonding reduces the bond strength of composite resin to enamel. Treating the bleached enamel surface with 10% sodium ascorbate or waiting 1 week reverses the reduction.

A comparison of tungsten-quartz-halogen, plasma arc and light-emitting diode light sources for the polymerization of an orthodontic adhesive

This study investigated whether there were differences between the debond stress and adhesive remnant index (ARI) of an adhesive cured with three different orthodontic light sources. Sixty sound premolar teeth were divided into three groups of 20. A standard pre-adjusted edgewise premolar bracket (Victory Series) was bonded to each tooth using a light-cured orthodontic adhesive, Transbond X. Group 1 (control) specimens were cured with an Ortholux XT (tungsten-quartz-halogen bulb) light for 20 seconds, group 2 with an Ortho lite (plasma arc) for 6 seconds and group 3 with an Ortholux LED light-emitting diode for 10 seconds. The specimens were debonded 24 hours later using a universal mechanical testing machine, operating at a crosshead speed of 0.5 mm minute(-1). The Weibull modulus and a Logrank test showed no statistically significant differences between the three groups for debond stress. The ARI was assessed at x10 magnification. The ARI scores for group 2 were significantly different (P < 0.01) from those of groups 1 and 3 (between which there was no significant difference). For group 2 there was a greater tendency for failure to occur at the adhesive/tooth interface than for the other two groups. There appears to be no reason why any of the three types of light source cannot be used in orthodontics. Polymerization, as effective as that produced by conventional bulb light sources, was obtained with the short exposure times recommended for the plasma arc or light-emitting diode sources.

In vivo debonding strength and enamel damage in two orthodontic debonding methods

Bracket debonding strength related to diverse debonding methods and enamel damage has not been assessed in vivo. The study hypothetized a direct relationship between these three parameters. Debonding strength was measured clinically in the wings method and base method on 50 patients in a split mouth method using a calibrated debonding plier. Brackets from 30 of these patients were scanned in SEM and EDAX for adhesive remnant index and enamel calcium remnants. Base method debonding force was significantly greater than wings method (163.5+/-68.7 N, 106.1+/-66.2 N, respectively, p < 0.001). A positive adhesive remnant index score was found in both methods (68.7%, 66.7%, respectively). Debonding strength vs. adhesive remnant index or calcium index scores were not correlated. However, the latter two were significantly correlated (0.524 < R < 0.895, p < 0.031). Half of the debonding failures developed at the adhesive enamel interface. The results warnts the potential of enamel damage during debonding.

Bond strength comparison of 2 self-etching primers over a 3-month storage period

The purpose of this in vitro study was to evaluate the shear-peel bond strength of 2 self-etching primer systems, Transbond Plus (3M/ Unitek, Monrovia, Calif) and First Step (Reliance Orthodontic Products, Itasca, Ill), with their respective adhesives, and compare them with a control adhesive system (Transbond XT, 3M/ Unitek) over a 3-month period. Two hundred seventy extracted human premolars were obtained and randomly divided into 9 groups of 30 teeth. Metal orthodontic brackets were bonded to the enamel, and each adhesive group was stored for 24 horrs (T1), 30 days (T2), or 3 months (T3) in deionized water at 37 degrees C. All bonded specimens were thermocycled at 10 degrees C and 50 degrees C for 24 hours before debonding. Brackets were debonded by using a shear-peel load on a testing machine at a cross-head speed of 2 mm/min. Bond failure was also evaluated. The shear-peel bond strengths of the 3 bonding systems were clinically acceptable with the possible exception of First Step at 30-day storage. Repeated measures analysis of variance showed a statistically significant (P < .0001) difference in mean bond strengths between the 3 adhesive systems. The shear-peel bond strength of the adhesives over the 3 time intervals showed statistically significant (P = .005) changes. In each group, there were statistically significant differences in shear-peel bond strength between time intervals T1-T2 and T2-T3 for Transbond Plus and T2-T3 for First Step. The change in mean shear-peel bond strength of the 3 adhesives demonstrated a consistent pattern of behavior over the 3 storage intervals. The lowest mean shear-peel bond strength values were noted at the 30-day storage. Bond failure analysis (adhesive remnant index) demonstrated mainly cohesive bond failures.

Anex vivoassessment of gingivally offset lower premolar brackets

OBJECTIVES

To compare the force to failure of standard premolar brackets to that of gingivally offset brackets and evaluate the site of bond failure between the two bracket types through the use of the Adhesive Remnant Index (ARI).

DESIGN

An ex vivo study.

SETTING

Dental Materials Science Laboratory, Dundee Dental School, Dundee.

MATERIALS AND METHODS

Forty extracted lower premolar teeth (caries free, extracted as part of orthodontic treatment, all donors living in a non-fluoridated area), divided into two equal size sample groups, as follows: Group 1: Victory Series (3M Unitek, Monrovia CA, USA) lower premolar brackets bonded to buccal surfaces with Transbond XT (3M Unitek, Monrovia CA). Group 2: Victory Series Gingivally Offset Bicuspid Brackets (3M Unitek, Monrovia CA) bonded to buccal surfaces with Transbond XT (3M Unitek, Monrovia CA). Force was applied in the occluso-gingival direction using an Instron Model 4469 Universal Testing Machine (Instron Ltd, High Wycombe, UK) operating at a cross-head speed of 0.5 mm/min and its value at failure determined. Following debond, the site of bond failure and ARI were recorded.

OUTCOME

Force to failure, site of bond failure and adhesive remnant index.

RESULTS

The Weibull analysis gave higher values for the force to failure at 5% level (200 v. 159 N) and at all other levels of probability of failure for the gingivally offset bracket. The non-parametric survival analysis using Gehan-Wilcoxon tests with Breslow's algorithm (p < 0.0001) showed significant difference in force to failure between bracket types. Chi-square tests showed no significant (p = 0.55) relationship between the site of bond failure and the bracket types.

CONCLUSION

Ex vivo testing suggests that there is a significant difference in the force to failure between gingivally offset and standard lower premolar brackets when force application is from an occluso-gingival direction. The site of failure (as given by the ARI) is insensitive to bracket types and force to failure.

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.

Bond strength comparison of moisture-insensitive primers

The objective of this in vitro bonding study was to evaluate the effectiveness of 2 moisture-insensitive primers, Assure (Reliance Orthodontic Products, Itasca, Ill) and MIP (3M Unitek, Monrovia, Calif) compared with a control hydrophobic primer, Transbond XT (3M Unitek). Six groups of 40 premolars were acid etched and bonded using metal orthodontic brackets with the following in vitro protocols: (1) Transbond XT primer and adhesive applied to a noncontaminated surface; (2) Assure primer applied after saliva contamination; (3) MIP primer applied after saliva contamination; (4) Assure primer reapplied after saliva contamination; (5) MIP reapplied after saliva contamination; and (6) Assure adhesive applied after saliva contamination of the primer. All bonded specimens were stored in deionized water at 37 degrees C for 30 days and thermocycled for 24 hours before debonding. Brackets were debonded using a shear-peel load on a testing machine, bond strength was measured in megapascals, and bond failure was analyzed by using the adhesive remnant index. In vitro shear-peel bond strengths were acceptable for all groups, and the bond strengths for Assure and MIP were not significantly affected by saliva contamination. The mean shear-peel bond strength of the control (14.82 MPa) was significantly higher (P <.001) than the contaminated groups with the exception of MIP group 5 (14.02 MPa). The values of the Assure primer and adhesive were less than the MIP primer and its respective adhesive; however, the hydrophilic Assure adhesive resin applied to a saliva-contaminated surface had acceptable bond strength. Bond failure analysis (adhesive remnant index) mainly showed adhesive bond failures. An increased frequency of enamel fractures at debond was noted, with the control group (1) and the MIP groups (3 and 5) having 22.5%, 12.5%, and 15%, respectively. The Assure groups had no enamel fractures.

An ex vivo assessment of a resin-modified glass ionomer cement in relation to bonding technique

OBJECTIVE

This study assessed a resin modified glass ionomer bonding system, Fuji ortho L.C. using different bonding techniques and compared it with a composite control (Transbond).

DESIGN

Ex vivo study. Twenty extracted premolar teeth in each group were bonded as follows: (i) Group 1 Control (Transbond); (ii) Group 2 Fuji ortho L.C. without an etch procedure/wet enamel surface; (iii) Group 3 Fuji ortho L.C. without an etch procedure/dry enamel surface; (iv) Group 4 Fuji ortho L.C. using a conventional acid etch technique.

OUTCOME

Shear bond strength, site of bond failure and adhesive remnant index.

RESULTS

Brackets bonded as recommended by the manufacturer (Group 2) have significantly (p < 0.001) lower bond strengths compared with the control (Group 1). Bonding with an etch technique (Group 4) will significantly (p < 0.001) increase the bond strength compared with the other Fuji groups. All the Fuji groups tended to fail at the enamel/resin interface with lower ARI scores compared with the control.

CONCLUSION

The lower bond strength of Fuji ortho L.C. would limit its use as a routine bonding agent. When bonded with an acid etch technique, the bond strength may be sufficient for low loading situations such as the upper anterior teeth.

Orthodontic bracket bonding with a plasma-arc light and resin-reinforced glass ionomer cement

Developments in light-curing technology have led to the introduction of a plasma-arc light-curing unit that delivers high-intensity output for faster curing. The purposes of this study were to determine the shear bond strengths of light-cured resin-reinforced glass ionomer cement cured with a plasma-arc light-curing unit and to evaluate the durability of the resultant bond strength with thermal cycling. Comparisons were made between light-cured resin-reinforced glass ionomer cement and light-cured composite resin. Two light-curing units were used in this study: a plasma-arc light-curing unit and a conventional light-curing unit. The mean shear bond strengths of light-cured resin-reinforced glass ionomer cement with the plasma-arc and the conventional light-curing units were 20.3 MPa and 26.0 MPa, respectively. An analysis of variance showed no statistically significant differences between the plasma-arc and the conventional light-curing units. Light-cured resin-reinforced glass ionomer cement and light-cured composite resin demonstrated similar bond strengths and exhibited no statistical differences. There was no statistical difference in bond strength between the teeth that were thermal cycled and those that were not. Failure sites for the brackets bonded with light-cured resin-reinforced glass ionomer cement appeared to be predominantly at the bracket-adhesive interface. The SDs of light-cured composite resin were high for both light-curing units. Whereas the coefficients of variation for light-cured resin-reinforced glass ionomer cement ranged from 20% to 30%, those of light-cured composite resin ranged from 40% to 60%. The bond strength of light-cured resin-reinforced glass ionomer cement cured with either a conventional light-curing unit or a plasma-arc light-curing unit surpassed the clinically required threshold. The plasma-arc light-curing unit may be an advantageous alternative to the conventional light-curing unit for orthodontic bracket bonding with both light-cured resin-reinforced glass ionomer cement and light-cured composite resin.

Shear bond strength of stainless steel orthodontic brackets with a moisture-insensitive primer

The purposes of this study were (1) to evaluate the shear bond strength of stainless steel orthodontic brackets bonded to dry and wet (with water and saliva) etched enamel with the use of the moisture-insensitive primer (MIP; Transbond; 3M Unitek, Monrovia, Calif) and (2) to evaluate the effectiveness of MIP with chemically activated (Concise; 3M Dental Products, St Paul, Minn) and light-activated (Transbond XT; 3M Unitek) resin. One hundred forty-four freshly extracted bovine teeth were divided into 12 groups (n = 12 teeth), and brackets were bonded with either of the 2 resins in combination with the conventional primer or MIP in dry or wet enamel surface conditions. The test specimens were mounted in a screw-driven mechanical testing machine (model 4204; Instron Corp, Canton, Mass) and subjected to a crosshead speed of 0.5 mm/min. The data were analyzed by 2-way analysis of variance. MIP with Concise produced slightly higher bond strengths compared with the conventional primers under wet conditions (MIP vs conventional: saliva, P <.001; water, P =.004). However, MIP in combination with Transbond XT produced comparable bond strengths on both the dry and wet etched enamel (dry, 10.14 MPa; water, 9.69 MPa; saliva, 8.90 MPa). The results of this study suggest that MIP be used only with light-activated composite resins.

Comparative assessment of light-cured resin-modified glass ionomer and composite resin adhesives: in vitro study of a new adhesive system

The ideal adhesive system is one that prevents decalcifications and has sufficient bond strength to withstand untimely impact forces on bonded brackets. The purpose of this investigation was to study and compare the bond strengths and adhesive remnant indexes of light-cured resin-modified glass ionomer and conventional resin adhesives. A new light-cured resin-modified glass ionomer adhesive was compared with the conventional adhesive systems. The effects of the new adhesive, with a system of etching and using adhesive promoters on the tooth enamel, as well as microetching the brackets, were analyzed. Comparisons were made (analysis of variance and the Tukey method) between this and other adhesive systems. The new adhesive system is indicated where prevention of decalcification and increased bond strength in noncompliant patients are indicated.

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.

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.

An ex vivo assessment of resin-modified glass ionomer bonding systems in relation to ceramic bracket debond

This ex vivo study assessed three new resin-modified glass ionomer cements (Fuji ORTHO LC, Vitremer, and Dyract-Cem) in relation to ceramic bracket removal. It was hypothesized that the use of these cements would facilitate bracket removal and eliminate debond complications Eighty extracted premolar teeth were divided into four groups of 20 teeth and bonded with Intrigue brackets using each of the resin-modified cements (groups 1, 2, and 3), the control group 4 was bonded with Concise chemically-cured adhesive. The teeth were debonded by applying a shear load using an Instron universal testing machine. The mean force to debond was calculated for each group and each tooth was examined under the stereomicroscope to record the site of bond failure and the Adhesive Remnant Index (ARI). The results showed that the resin-modified cements were very effective at eliminating ceramic bracket debond problems. Bracket fracture was eliminated compared with a 40 per cent fracture rate with the control and the ARI scores were all reduced. The elimination of debond problems appears to be related to the significantly reduced (P < 0.001 using ANOVA and Tukey tests) mean and maximal debond forces compared with the control.

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.