Effects of a fluoride-containing casein phosphopeptide-amorphous calcium phosphate complex on the shear bond strength of orthodontic brackets

The purpose of this study was to investigate the effects of enamel pre-treatment with a new fluoride-containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) complex on the shear bond strength (SBS) of brackets bonded with etch-and-rinse or self-etching adhesive systems. The material comprised 66 extracted human premolars randomly divided into six equal groups with respect to the enamel pre-treatment and adhesive system employed: 1. No pre-treatment and brackets bonded with the etch-and-rinse adhesive system (Transbond XT). 2. Pre-treatment with fluoride-containing CPP-ACP paste (MI Paste Plus) and Transbond XT. 3. Pre-treatment with non-fluoride CPP-ACP paste (MI Paste) and Transbond XT.4. No pre-treatment and brackets bonded with the self-etching adhesive system (Transbond Plus). 5 and 6. Enamel pre-treated as for groups 2 and 3, respectively, and the Transbond Plus. Bonded specimens were subjected to thermal cycling (×1000) before SBS testing. The residual adhesive on the enamel surface was evaluated after debonding with the adhesive remnant index (ARI). Data evaluation was made using one-way analysis of variance and Tukey test for SBS results, and Kruskal-Wallis test for ARI results. The results showed that enamel pre-treatment with either fluoride or non-fluoride CPP-ACP paste had no significant effect on the SBS of the self-etching adhesive system (P > 0.05). Enamel pre-treatment with non-fluoride CPP-ACP in group 3 significantly reduced the SBS of the etch-and-rinse adhesive (P < 0.001), while pre-treatment with fluoride-containing CPP-ACP paste (groups 2 and 5) did not affect debonding values (P > 0.05). The fluoride-containing CPP-ACP did not compromise the SBS of brackets bonded with the tested etch-and-rinse and self-etching systems, but its non-fluoride version significantly decreased the SBS of the etch-and-rinse adhesive system.     

Effects of self-etching primer on shear bond strength of orthodontic brackets at different debond times

OBJECTIVE: To evaluate the effect of a self-etching primer on shear bond strengths (SBS) at the different debond times of 5, 15, 30, and 60 minutes and 24 hours. MATERIALS AND METHODS: Brackets were bonded to human premolars with different etching protocols. In the control group (conventional method [CM]) teeth were etched with 37% phosphoric acid. In the study group, a self-etching primer (SEP; Transbond Plus Self Etching Primer; 3M Unitek, Monrovia, Calif) was applied as recommended by the manufacturer. Brackets were bonded with light-cure adhesive paste (Transbond XT; 3M Unitek) and light-cured for 20 seconds in both groups. The shear bond test was performed at the different debond times of 5, 15, 30 and 60 minutes and 24 hours. RESULTS: Lowest SBS was attained with a debond time of 5 minutes for the CM group (9.51 MPa) and the SEP group (8.97 MPa). Highest SBS was obtained with a debond time of 24 hours for the CM group (16.82 MPa) and the SEP group (19.11 MPa). Statistically significant differences between the two groups were not observed for debond times of 5, 15, 30, or 60 minutes. However, the SBS values obtained at 24 hours were significantly different (P < .001). CONCLUSIONS: Adequate SBS was obtained with self-etching primer during the first 60 minutes (5, 15, 30 and 60 minutes) when compared with the conventional method. It is reliable to load the bracket 5 minutes after bonding using self-etching primer (Transbond Plus) with the light-cure adhesive (Transbond XT).     

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

Aim

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

Material and Methods

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

Results

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

Conclusion

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

Bond strength comparison and scanning electron microscopic evaluation of three orthodontic bonding systems

This study sought to assess the efficacy of two self-etching primer systems (Transbond Plus and Beauty Ortho Bond) on orthodontic brackets. Therefore, shear bond strengths and bracket-adhesive failure modes (ARI scores) were determined and compared against an etch-and-rinse adhesive system (Transbond XT) under two experimental conditions (dry and saliva application). Shear bond strength test was performed at a crosshead speed of 0.5 mm/min, while enamel surfaces and enamel-adhesive interfaces were examined with SEM. There were no significant differences between Transbond XT (9.15 MPa) and Transbond Plus (9.74 MPa) under the dry condition, whereas that of Beauty Ortho Bond (6.47 MPa) was significantly lower than these two systems. Under SEM examination, both self-etching primers showed a milder etching effect and decreased depth of resin penetration into intact enamel than Transbond XT. In conclusion, results of this study showed that both self-etching systems seemed to offer more merits than conventional acid etching because of fewer irreversible changes to enamel.     

SHEAR BOND STRENGTH OF METALLIC BRACKETS: INFLUENCE OF SALIVA CONTAMINATION

Objective:

To evaluate the influence of saliva contamination on shear bond strength and the bond failure pattern of 3 adhesive systems (Transbond XT, AdheSE and Xeno III) on orthodontic metallic brackets bonded to human enamel.

Material and Methods:

Seventy-two permanent human molars were cut longitudinally in a mesiodistal direction, producing seventy-two specimens randomly divided into six groups. Each system was tested under 2 different enamel conditions: no contamination and contaminated with saliva. In T, A and X groups, the adhesive systems were applied to the enamel surface in accordance with manufacturer''s instructions. In TS, AS and XS groups, saliva was applied to enamel surface followed by adhesive system application. The samples were stored in distilled water at 37°C for 24 h, and then tested for shear bond strength in a universal testing machine (Emic, DL 2000) running at a crosshead speed of 1 mm/min. After bond failure, the enamel surfaces were observed under an optical microscope at 40x magnification.

Results:

The control and contaminated groups showed no significant difference in shear bond strength for the same adhesive system. However, shear bond strength of T group (17.03±4.91) was significantly higher than that of AS (8.58±1.73) and XS (10.39±4.06) groups (p<0.05). Regarding the bond failure pattern, TS group had significantly higher scores of no adhesive remaining on the tooth in the bonding area than other groups considering the adhesive remnant index (ARI) used to evaluate the amount of adhesive left on the enamel.

Conclusion:

Saliva contamination showed little influence on the 24-h shear bond strength of orthodontic brackets.     

BOND STRENGTH AND MORPHOLOGY OF ENAMEL USING SELF-ETCHING ADHESIVE SYSTEMS WITH DIFFERENT ACIDITIES

Objectives:

To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters.

Material and methods:

Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (burcut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm² cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey''s test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope.

Results:

The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system.

Conclusion:

Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed.     

Bracket bond strength comparison between new unfilled experimental self-etching primer adhesive and conventional filled adhesives

Objective:To determine if a new unfilled experimental self-etching primer (SEP) adhesive system (SBP-40TX + C&B Metabond) that incorporates a methyl methacrylate–based 4-META/TBB (4-methacryloxyethyl trimellitate anhydride tri-n-butyl borane) resin can provide adequate shear bond strength (SBS) when used for bonding orthodontic brackets.Methods and Materials:Forty-eight human maxillary premolars were randomly divided into three groups of 16 specimens each. Brackets were bonded with three bonding systems. A filled Bis-GMA/TEGDM (triethylene glycol dimethacrylate)–based SEP adhesive system (Transbond Plus) and an unfilled conventional etch-and-rinse adhesive system (C&B Metabond) were used for comparison. The SBS for each sample was examined with a universal testing machine, and the Adhesive Remnant Index score was calculated. Enamel surfaces after conditioning were examined using a scanning electron microscope. Data were compared by one-way analysis of variance and a χ² test.Results:The experimental SEP showed a milder etching pattern than Transbond Plus SEP. No statistically significant differences in the mean SBS were found between the specimens bonded with the unfilled experimental SEP adhesive system (10.0 MPa) and the filled SEP adhesive system (8.7 MPa). The unfilled experimental SEP adhesive system showed less residual adhesive than the filled SEP adhesive system.Conclusions:The unfilled experimental SEP adhesive system showed a clinically sufficient SBS that was equivalent to the filled SEP adhesive system.     

A New Generation of Self-etching Adhesives: Comparison with Traditional Acid Etch Technique

OBJECTIVE: The aim of this study was to determine the shear bond strength (SBS), etching pattern and depth, and debonding performance of several market-leading, self-etching (SE) adhesives primarily used in restorative dentistry (iBond, Clearfil S(3) Bond, Clearfil Protect Bond, AdheSE, XenoIII), two experimental self-etching adhesives (exp. Bond 1, exp. Bond 2) and one experimental self-etching cement (SE Zement) used with and without prior phosphoric acid-etching, and to compare them to an orthodontic self-etching product (Transbond Plus SE Primer) and to traditional acid-etch technique (Transbond XT Primer, phosphoric acid) MATERIALS AND METHODS: All adhesives were applied on pumiced and embedded bovine incisors following the manufacturers' instructions. Then one bracket each (coated with Transbond XT composite) was bonded (n = 20). Transbond XT was polymerized for 20 s from the incisal and gingival sides using a halogen device positioned at a constant 5 mm from and a 45 degrees angle to the specimen. The specimens were stored in distilled water for 24 h at 37 degrees C before measuring SBS. The ARI (adhesive remnant index) for all specimens was determined from the sheared-off brackets of each. After conditioning, the surface texture was morphologically evaluated from scanning electron microscope (SEM) images, while the etching depth was determined using a confocal laser-scanning microscope (CLSM). All groups were tested for normal distribution and analyzed by applying ANOVA, Kruskal-Wallis or the t test. In addition, a Bonferroni correction was used. RESULTS: The median values of the SBS tests were: SE Zement 3.0 MPa, SE Zement preceded by phosphoric acid etching 11.2 MPa, experimental bond 1: 7.4 MPa, experimental bond 2: 5.6 MPa, iBond 8.1 MPa, Clearfil S(3) Bond 14.1 MPa, Clearfil Protect Bond 16.6 MPa, Clearfil SE Bond 15.9 MPa, AdheSE 16.0 MPa, XenoIII 16.1 MPa, Transbond SE Primer 20.7 MPa, acid-etching+Transbond XT Primer 21.0 MPa. With the exception of iBond, we observed no significant differences among the self-etching adhesives used in Restorative Dentistry or in comparison to the Transbond Plus SE Primer. No significant differences were apparent even when compared to the Transbond XT Primer after phosphoric acid-etching. Both experimental bonding agents and SE Zement without acid etching performed significantly worse than the products mentioned above, failing to demonstrate sufficient adhesive strength. SEM examination revealed less distinctive enamel-etching patterns for self-etching products than for phosphoric acid-etching. CLSM analysis revealed etching depths between 0.5 and 20 microm depending on the product. When self-etching products were used, less residual composite remained on the enamel surface than after phosphoric acid-etching. CONCLUSIONS: All the adhesives tested are suitable for bonding orthodontic brackets and to reduce the risk of enamel fracture while minimizing etching depth, which in turns means less conditioning-related enamel loss. More development is needed to improve the etching performance of both experimental bonding agents and SE Zement.     

Bond strength of self-adhesive resin cements to tooth structure

Objectives

The aim of this study was to evaluate the strength of the bond between newly introduced self-adhesive resin cements and tooth structures (i.e., enamel and dentin).

Methods

Three self-adhesive cements (SmartCem2, RelyX Unicem, seT SDI) were tested. Cylindrical-shaped cement specimens (diameter, 3 mm; height, 3 mm) were bonded to enamel and dentin. Test specimens were incubated at 37 °C for 24 h. The shear bond strength (SBS) was tested in a Zwick Roll testing machine. Results were analyzed by one-way ANOVA and t-test. Statistically significant differences were defined at the α = 0.05 level. Bond failures were categorized as adhesive, cohesive, or mixed.

Results

The SBS values ranged from 3.76 to 6.81 MPa for cements bonded to enamel and from 4.48 to 5.94 MPa for cements bonded to dentin (p > 0.05 between surfaces). There were no statistically significant differences between the SBS values to enamel versus dentin for any given cement type. All cements exhibited adhesive failure at the resin/tooth interface.

Conclusions

Regardless of their clinical simplicity, the self-adhesive resin cements examined in this study exhibit limited bond performance to tooth structures; therefore, these cements must be used with caution.     

Effect of self-etching primers on bond strength--are they reliable?

Currently introduced self-etching primers combine conditioning and priming agents into a single product. The purpose of this study was to determine the effects of using three self-etching primers on the shear bond strength (SBS) of orthodontic brackets and on the bracket/adhesive failure mode. Brackets were bonded to extracted human teeth according to one of four protocols. In the control group, teeth were etched with 37% phosphoric acid. In the experimental groups, the enamel was conditioned with three different self-etching primers, Clearfil SE Bond (CSE), Etch & Prime 3.0 (EP3), or Transbond Plus (TBP), as suggested by the manufacturer. The brackets were then bonded with Transbond XT in all groups. The present in vitro findings indicate that conditioning with TBP before bonding orthodontic brackets to the enamel surface resulted in a significantly (P < or = .001) higher SBS (mean, 16.0 +/- 4.5 MPa) than that found in CSE, EP3, and the control (acid-etched [AE]) groups. CSE produced bond strength values (mean 11.5 +/- 3.3 MPa) that are statistically comparable to those produced by acid etching (mean 13.1 +/- 3.1 MPa). The use of EP3 for enamel conditioning resulted in the lowest mean SBS value (mean 9.9 +/- 4.0 MPa). A comparison of the adhesive remnant index scores indicated that there was more residual adhesive remaining on the teeth that were treated with conventional acid etching than in the CSE and EP3 groups. In the TBP group, the failure sites were similar to those of the AE group but different from those of the CSE group.     

Effects of enamel sealing on shear bond strength and the adhesive remnant index

Objectives

Selected combinations of materials were used to create tooth–adhesive–bracket complexes to evaluate shear bond strength (SBS) and the adhesive remnant index (ARI) with regard to enamel sealing.

Methods

Four adhesive systems also appropriate for use as enamel sealants were combined with four bracket types, resulting in 16 adhesive–bracket combinations, each of which was tested on 15 permanent bovine incisors. Sealant–adhesives included two recently introduced fluoride-releasing systems (Riva bond LC^® and go!^®), one established primer (Opal^® Seal?), and one commonly used adhesive as control (Transbond? XT). Brackets included two metal (discovery^® by Dentaurum and Sprint^®) and two ceramic (discovery^® pearl and GLAM^®) systems. After embedding the bovine teeth, bonding the brackets to their surface, and storing the resultant samples as per DIN 13990-2 with modifications, an SBS test was performed by applying the shear force directly at the bracket base in an incisocervical direction. Then the ARI scores were determined.

Results

Discovery^® + Transbond? XT yielded the highest (47.2 MPa) and GLAM^® + go!^® the lowest (17.0 MPa) mean SBS values. Significant differences (p < 0.0001) were found between metal and ceramic brackets of the same manufacturers (Dentaurum and Forestadent). Our ratings of the failure modes upon debonding predominantly yielded ARI 0 or 1. The high SBS values and low ARI scores observed with discovery^® + Transbond XT? were reflected in a high rate of enamel fracture, which occurred on 11 of the 15 tooth specimens in this group.

Conclusions

All sealant–bracket combinations were found to yield levels of SBS adequate for clinical application. SBS values and ARI scores varied significantly depending on which sealant–brackets were used.

     

An in-vitro investigation into the use of a single component self-etching primer adhesive system for orthodontic bonding: a pilot study

OBJECTIVE: This pilot study assessed force to debond (N); time, and site of bond failure of a single component self-etching primer (SEP) and adhesive system, Ideal 1 (GAC International Inc., USA) and compared it with the conventional acid etch and rinse regimen using 37% o-phosphoric acid solution and either Transbond XT (3M Unitek) or Ideal 1 adhesive. DESIGN: In vitro laboratory study. SETTING: Bristol Dental Hospital, UK. Sept 2003-Sept 2004. MATERIAL AND METHODS: Nine groups of 20 premolars were bonded using metal orthodontic brackets using three protocols: (1) 37% o-phosphoric acid etch and Transbond XT adhesive; (2) 37% o-phosphoric acid and Ideal 1 adhesive; (3) Ideal 1 SEP and Ideal 1 adhesive. Force to debond and locus of bond failure were determined at three time intervals. RESULTS: Enamel pre-treatment prior to bonding, namely SEP versus conventional etching had no significant effect on the median force to debond with the Ideal 1 adhesive. Similarly, when the enamel was conventionally etched, the adhesive type, namely Ideal 1 or Transbond XT, had no significant effect on the measured force to debond. However, there appeared to be differences in the locus of bond failure: failure predominated at the enamel/adhesive interface for the Transbond XT conventional etch group and at adhesive/bracket interface for the Ideal 1 SEP and adhesive group and the Ideal 1 adhesive conventional etch group. CONCLUSION: These results suggested that the complete Ideal 1 SEP and adhesive system might be successful in vivo leading therefore to a clinical trial. However, implications for clean up time are discussed and improvements to in vitro study designs are advised.     

Fluoride-releasing adhesive and antimicrobial self-etching primer effects on shear bond strength of orthodontic brackets

OBJECTIVE: To determine whether the combination of a new antimicrobial primer and a fluoride-releasing adhesive will affect the shear bond strength (SBS) and the bracket/adhesive failure mode. MATERIALS AND METHODS: A total of 120 extracted human teeth were randomly divided into three groups of 40 specimens each (20 incisors, 20 premolars). Transbond XT was used in group 1, a fluoride-releasing adhesive (Kurasper F) was used in group 2, and a new antimicrobial self-etching primer (Clearfil Protect Bond) was applied in combination with Kurasper F in group 3. A universal testing machine was used to determine the SBS, and the adhesive remaining after debonding was assessed. RESULTS: No enamel fractures were detected in any of the specimens. SBS values for incisors and premolars were 11.40 +/- 4.65 MPa and 10.37 +/- 3.36 MPa in group 1, 14.50 +/- 4.22 MPa and 13.06 +/- 5.13 MPa in group 2, and 14.79 +/- 4.10 MPa and 14.60 +/- 3.55 MPa in group 3. Statistically significant difference (P = .001) was found in the premolars in group 3 revealing the highest mean SBS. Significantly lower adhesive remnant index (ARI) values (median ARI value of 1) were detected in group 3 when compared with groups 1 and 2. CONCLUSIONS: Considering the acceptable bond strength and the mode of failure, the combination of the new antimicrobial primer with the fluoride-releasing adhesive is recommended for clinical use.     

Shear bond strength of orthodontic resins after caries infiltrant preconditioning

Objective:To investigate the influence of caries infiltrant preconditioning on the shear bond strength of orthodontic resin cements on sound and demineralized enamel.Materials and Methods:Stainless-steel brackets were bonded to sound or artificially demineralized (14 d, acidic buffer, pH 5.0) bovine enamel specimens using a resin cement or a combination of caries infiltrant preconditioning (Icon, DMG) and the respective resin cement (light-curing composite: Heliosit Orthodontic, Transbond XT, using either Transbond XT Primer or Transbond Plus Self Etching Primer; light-curing resin-modified glass ionomer cement: Fuji Ortho; or self-curing composite: Concise Orthodontic Bonding System). Each group consisted of 15 specimens. Shear bond strength was evaluated after thermo-cycling (10,000×, 5°C to 55°C) at a crosshead speed of 1 mm/min, and data were statistically analyzed by analysis of variance, Mann-Whitney test, and Weibull statistics. Adhesive Remnant Index (ARI) scores and enamel fractures were determined at 25× magnification and were statistically analyzed by regression analyses (P < .05).Results:The caries infiltrant system significantly increased the shear bond strength of Transbond XT Primer, Transbond Plus Self Etching Primer, and Fuji Ortho in sound specimens, and of all resin cements except for the Concise Orthodontic Bonding System in demineralized enamel. Overall, caries infiltrant preconditioning decreased significantly the number of enamel fractures, but it did not affect ARI scores.Conclusion:Preconditioning of sound and demineralized enamel with the caries infiltrant system did not impair but rather increased the shear bond strength of most orthodontic resin cements while decreasing the risk of enamel fracture at debonding.     

Shear bond strength of a new fluoride-releasing orthodontic adhesive

This study evaluated the shear bond strength of stainless steel brackets bonded to enamel with a new fluoride-releasing orthodontic adhesive system. A total of 140 extracted human bicuspids were randomly divided into four groups. Group I (Transbond XT) was a control group in which enamel was etched with phosphoric acid. For the remaining groups, enamel was conditioned with a self-etching primer (SEP): Group II (Transbond Plus), Group III (BeautyOrtho Bond), and Group IV (BeautyOrtho Bond + Salivatect). Stainless steel brackets were bonded to all tooth samples. After which, the samples were stored, thermocycled, tested, and statistically analyzed. Besides bond strength evaluation, the adhesive remnant index (ARI) was also evaluated. The shear bond strengths of Groups II, III, and IV were significantly lower than Group I, and Group II was significantly greater than that of Group III. Concerning ARI scores, no significant differences were found between the groups. Further, no enamel fracture was observed during shear bond test with the new SEP. In conclusion, when enamel was conditioned with the new SEP, the mean values of shear bond strength yielded were lower than when it was etched with 37% phosphoric acid. Nonetheless, these mean values were higher than the average suggested by Reynolds as optimum for clinical treatment.     

The effect of modifying the self-etchant bonding protocol on the shear bond strength of orthodontic brackets

OBJECTIVE: To compare the shear bond strength (SBS) of orthodontic brackets when the self-etching primer (SEP) and the bracket adhesive are light cured either separately or simultaneously. MATERIALS AND METHODS: Seventy-five human molars were randomly divided into five equal groups. Brackets precoated with Transbond XT composite adhesive were used. The five protocols were: Group 1 (control), the SEP Transbond Plus was applied, brackets placed, and adhesive light cured for 20 seconds; Group 2, SEP Adper Prompt L-Pop was applied, light cured, brackets placed, and light cured; Group 3, the same SEP as in Group 2 was used, however, the SEP and bracket adhesive were light cured together; Group 4, SEP Clearfil S3 Bond was applied, light cured, brackets placed, and light cured; and Group 5, the same SEP as in group 4 was used, however, the SEP and the adhesive were light cured together. The teeth were debonded using a universal testing machine, and the enamel was examined for residual adhesive. Analysis of variance was used to compare the SBS. RESULTS: The SBS of Clearfil S3 Bond after one light cure and two light cures were significantly greater than the bonds of brackets using Transbond Plus. Brackets bonded using Adper Prompt L-Pop after one light cure and two light cures were not significantly different from the other groups. The groups did not differ significantly in their bracket failure modes. CONCLUSION: Only one light curing application is needed to successfully bond brackets when using SEPs and adhesives. This approach can potentially reduce technique sensitivity as well as chair time.     

Comparison of shear bond strengths of orthodontic brackets bonded with flowable composites

This study evaluated the shear bond strengths of orthodontic brackets bonded to human premolars using five different combinations of flowable composites and one-step self-etching adhesives (n=12): (1) Adper Easy Bond+Filtek Supreme XT Flow; (2) Futurabond NR+Grandio Flow; (3) Clearfil S3 Bond+Clearfil Majesty Flow; (4) AdheSE One+Tetric EvoFlow; and (5) Transbond Plus Self Etching Primer+Transbond XT Light Cure Adhesive. After shear bond strength testing, adhesive remnant index (ARI) scores were given according to the amount of adhesive and resin remaining on the brackets. On shear bond strength, there were no statistically significant differences between Groups 2 and 4 and between Groups 3 and 5 (p>0.05). On ARI scores, the predominant ARI scores in Groups 1, 2, 3, and 5 were 4, 2, 5, and 4 respectively; in Group 4, they were 0 and 4. Results showed that some combinations of flowable composites and self-etching adhesives might not be suitable for orthodontic use due to their low shear bond strengths and high ARI scores -with the latter signaling the risk of damaging the enamel surface during debonding.     

Early shear bond strength of a one-step self-adhesive on orthodontic brackets

OBJECTIVE: The purpose of this study was to determine whether a self-adhesive universal cement, RelyX Unicem (3M ESPE, Seefeld, Germany), can be used successfully to bond orthodontic brackets to enamel. MATERIALS AND METHODS: Forty human molars were cleaned, mounted, and randomly divided into two groups: 20 orthodontic brackets were bonded to teeth using RelyX Unicem, and 20 brackets were bonded using the Transbond XT (3M Unitex, Monrovia, Calif) adhesive system. The teeth were debonded within 30 minutes after initial bonding using a universal testing machine. After debonding, the enamel surface was examined under 10x magnification to determine the amount of residual adhesive remaining on the tooth. Student's t-test was used to compare the shear bond strength (SBS) of the two groups, and the chi-square test was used to compare the Adhesive Remnant Index (ARI) scores for the two adhesive systems. RESULTS: The mean SBS of the brackets bonded using the RelyX Unicem was 3.7 +/- 2.1 MPa and was significantly lower (t = 2.07, P = .048) than the SBS of the brackets bonded with the Transbond system (x = 5.97 +/- 4.2 MPa). The comparisons of the ARI scores between the two groups (chi(2) = 17.4) indicated that bracket failure mode was significantly different (P = .002) with more adhesive remaining on the teeth bonded with Transbond XT. CONCLUSIONS: The SBS of the self-adhesive universal cement needs to be increased for it to be successfully used for bonding orthodontic brackets.     

SHEAR BOND STRENGTH OF ORTHODONTIC BRACKETS TO ENAMEL UNDER DIFFERENT SURFACE TREATMENT CONDITIONS

The purpose of the present study was to evaluate the shear bond strength to enamel and the adhesive remnant index (ARI) of both metallic and polycarbonate brackets bonded under different conditions. Ninety bovine permanent mandibular incisors were embedded in acrylic resin using PVC rings as molds and assigned to 6 groups (n=15). In Groups 1 (control) and 3, metallic and polycarbonate orthodontic brackets were, respectively, bonded to the enamel surfaces using Transbond XT composite according to the manufacturer''s recommendations. In Groups 2 and 4, both types of brackets were bonded to enamel with Transbond XT composite, but XT primer was replaced by the OrthoPrimer agent. In Groups 5 and 6, the polycarbonate bracket bases were sandblasted with 50-μm aluminum-oxide particle stream and bonded to the enamel surfaces prepared under the same conditions described in Groups 3 and 4, respectively. After bonding, the specimens were stored in distilled water at 37°C for 24 hours and then submitted to shear bond strength test at a crosshead speed of 0.5 mm/min. The results (MPa) showed no statistically significant difference between Groups 4 and 6 (p>0.05). Likewise, no statistically significant differences (p>0.05) were found among Groups 1, 2, and 5, although their results were significantly lower than those of Groups 4 and 6 (p<0.05). Group 3 had statistically significant lower bond strength than Groups 2, 4, and 6, but no statistically significant differences were found on comparison to Groups 1 and 5. A larger number of fractures at the bracket/composite interface were evidenced by the ARI scores. OrthoPrimer bonding agent yielded higher bond strength in the groups using either conventional or sandblasted polycarbonate brackets, which was not observed in the groups using metallic brackets.     

Shear bond strength of brackets bonded with hydrophilic and hydrophobic bond systems under contamination

Objective:To compare, in vitro, the shear bond strength (SBS) of two bond systems: Transbond XT/XT primer (TXT/XT) and Transbond Plus Color Change/Transbond Self Etching Primer (TPCC/TSEP).Materials and Methods:Each system was examined under four enamel surface conditions (dry, water, saliva, and blood), and 160 bovine teeth were divided into eight groups of 20 according to enamel surface condition. Group 1 used TPCC/TSEP and Group 2 used TXT/XT under dry conditions; Group 3 used TPCC/TSEP and Group 4 used TXT/XT with water; Group 5 used TPCC/TSEP and Group 6 used TXT/XT under saliva; and Group 7 used TPCC/TSEP and Group 8 used TXT/XT with blood. Brackets were bonded, and the samples were thermocycled 500 times between 5°C and 55°C; they were then submitted to a shear bond test with a universal testing machine with a 50 kgf load cell at 5 mm/min.Results:Although water and saliva affected TXT/XT more than they affected TPCC/TSEP, there were no significant differences among the groups (Groups 3 and 4: P  =  .940; Groups 3 and 5 and Groups 4 and 6: P  =  1.000; Groups 3 and 6: P  =  .988; Groups 4 and 5: P  =  .690; and Groups 5 and 6: P  =  .861).Conclusions:The presence of blood resulted in the lowest SBS from both bond systems, but especially from TXT/XT. TPCC/TSEP resulted in a higher SBS than TXT/XT under all conditions except the dry enamel surface.