Evaluation of shear bond strength, adhesive remnant index, and degree of conversion of orthodontic composite adhesives: An in vitro study using human premolars.

To test the null hypothesis that there is no significant difference in the shear bond strength (SBS) and Adhesive Remnant Index (ARI) scores of new vs reconditioned self-ligating brackets. One hundred and twenty permanent extracted bovine teeth were embedded in resin blocks. Three different new and reconditioned self-ligating orthodontic brackets (Smart Clip [3M Unitek]; Quick [Forestadent]; and Damon3MX [Ormco]) were tested. Scanning electron microphotographs of the different new (groups 1, 3, and 5) and reconditioned (groups 2, 4, and 6) bracket bases were taken before starting the experiments. Brackets were then bonded to the teeth using an orthodontic adhesive and were then tested in shear mode using an Instron Universal Testing Machine. ARI scores were then recorded. Statistical analysis was performed to determine significant differences in SBS and ARI Scores. Smart Clip and Damon3MX reconditioned brackets showed significantly lower SBS than did new ones. On the contrary, Quick reconditioned brackets showed significantly higher SBS than did new ones. No significant differences in ARI scores were found after the reconditioning process for the three different brackets tested. The in-office reconditioning procedure alters the SBS of self-ligating brackets, although SBS values still remain clinically acceptable.

Aim. This study aims to evaluate the effect of acidic food simulant and (acetic acid 3%) on the shear bond strength (SBS) and adhesive remnant index (ARI) scores of one conventional and three different self-ligating brackets with different base designs. Materials and Methods. Freshly extracted first maxillary premolars (n = 160) were embedded in resin blocks. A conventional stainless steel bracket, Equilibrium 2, and three types of self-ligating brackets, Speed, In-Ovation R, and Damon 3MX, were bonded to teeth and exposed to distilled water (groups 1, 3, 5, and 7) or acetic acid 3% (groups 2, 4, 6, 8) for 12 weeks. SBS and ARI were calculated and statistical analysis was performed with the analysis of variance (SBS) or χ 2 test (ARI) to compare values between the different groups. Results. Equilibrium 2 and In-Ovation R showed a significantly lower SBS in the acidic environment than in distilled water. Significant differences in ARI scores were found for Equilibrium 2 after immersion in an acidic environment, shifting from 0 in distilled water to 2 in an acidic environment. Conclusions. Equilibrium 2 and In-Ovation R brackets showed a significant decrease in SBS after a 12-week immersion in acetic acid 3%, although all groups showed clinically acceptable SBS. Equilibrium 2 showed significant differences in ARI scores when exposed to acetic acid 3%.

Background: Fibre reinforced composite bars (FRC) have applications as bonded retainers, space maintainers and anchorage/movement units. However, the bond strength of attachments to FRC anchorage bars is unknown. Aims: To compare the shear bond strengths of brackets bonded immediately to FRCs with different orthodontic adhesive systems and bonded with the same adhesives after a 48-hour delay, abraded with a diamond bur and etched with phosphoric acid. Method: One hundred and five recently extracted upper premolars were randomly assigned to seven groups (N = 15 teeth per group). FRCs were bonded to the buccal surfaces of the teeth and stainless steel orthodontic brackets were bonded to the FRCs with the following adhesive systems: Group 0 (Tetric Flow); Groups 1, 2 and 3 (Immediate bonding with chemically cured, no-mix and light cured composites, respectively, the bars covered with Tetric Flow); Groups 4, 5 and 6 (Bonding to FRCs delayed 48 hours, then bonded with chemically cured, no-mix and light cured composites, respectively, the bars covered with Tetric Flow). The FRC bars in Groups 4, 5 and 6 were abraded with a coarse-grit diamond bur before bonding the attachments to the bars. The shear bond strengths (SBS) were measured with a universal testing machine, and the adhesive remaining on the teeth after debonding was scored with the Adhesive Remnant Index (ARI). Data were analysed using analysis of variance (ANOVA), Duncan’s post-hoc and Fisher’s Exact test. Results: There were no statistically significant SBS differences between Groups 0 (Mean SBS: 9.56 MPa), 1 (Mean SBS: 9.74 MPa), 2 (Mean SBS: 10.72 MPa) or 3 (Mean SBS: 9.54 MPa). Groups 4, 5 and 6 (Bonding delayed by 48 hours) had SBSs of 11.79 MPa, 11.63 MPa and 13.11 MPa, respectively, and were significantly higher than the SBSs in Groups 1, 2 and 3 (Immediate bonding). There were no significant differences in ARI scores among the groups. Conclusions: The mean SBSs in all groups fell within the clinically acceptable range (> 7 MPa). The combination of a 48-hour delay between placement of an FRC bar and bonding an attachment, abrading the FRC with a diamond bur and etching with phosphoric acid resulted in higher bond strengths.

The objective of this study was to compare shear bond strength (SBS) and adhesive remnant index (ARI) of domestically made orthodontic adhesives to a commercial orthodontic adhesive, Transbond XT (3M Unitek, USA). Three formulas of an in-house orthodontic adhesive were divided according to monomer ratio (BisGMA:TEGDMA) into group 1 (8:2), 2 (7:3), and 3 (6:4), respectively, with 60-70 weight % of filler amount and 0.5 % of photoinitiator (TPO). Eighty upper human premolars (20 of each group) were bonded with stainless-steel brackets with these experimental and control adhesives. All were cured by LED light-cured unit for 20 seconds. After polymerization for 24 hours, a universal testing machine was used to apply an occlusal shear force to the enamel/bracket interface at a speed of 0.5 mm/min. The ARI scores were evaluated for each debonded tooth. Mean SBS values were analyzed statistically using the One-way ANOVA and the Tukey’s test for multiple comparison. Chi-square test was used to determine significant difference in the ARI scores. The results showed that there was statistical difference in the mean SBS of 4 groups (P<.001). The SBS value of group 1, 2, 3, and control was 18.79 MPa, 18.58 MPa, 23.30 MPa, and 28.02 MPa, respectively. Chi-square comparison for the ARI indicated that there was significant difference (P=.012) between the groups. In conclusion, the experimental adhesive of group 3 yields the higher SBS than in group 1 and group 2. Although these adhesives provide a lower shear bond strength than Transbond XT, they were acceptable for clinical use. Most failures of Transbond XT were found between adhesive-bracket interface, whereas the three in-house experimental adhesives were found mixed failure patterns of ARI.

Objectives To evaluate the effect of adhesive systems on shear bond strength (SBS) of metal brackets bonded to different ceramic surfaces. Materials and methods This study was carried out on 120 ceramic blocks. Ceramic blocks were divided into two main groups (60 blocks of VITABLOCS Mark II in group I and 60 blocks of IPS emax CAD in group II). All ceramic blocks were embedded in acrylic blocks with their surfaces facing upward. All ceramic blocks were acid etched with 9.6% HFA followed by silane application. Each group was divided into three subgroups (20 blocks/each). Each subgroup was bonded with a different adhesive system. Subgroup I was Transbond XT, subgroup II was Blugloo, subgroup III was Assure Plus + GoTo adhesive. All ceramic blocks were light cured then stored for 24 h in distilled water before SBS test. Adhesive Remnant Index (ARI) was evaluated to determine the site of bond failure. Analysis of variance and standard Student’s t test were used to analyze the differences in SBS. The χ2 test was used to evaluate differences in ARI scores among groups. Results Significant differences in SBS among groups were found (P ≤ 0.05). In group I, Blugloo had the highest SBS 19.34 MPa, followed by Assure Plus 16.10 MPa while Transbond XT had the lowest SBS 12.30 MPa. In group II, Blugloo also had the highest SBS 16.83 MPa, while Transbond XT also had the lowest SBS 10.50 MPa. There were no statistically significant differences in ARI scores among the subgroups of groups I and II (P > 0.05). Conclusions SBS of metal brackets bonded to VITABLOCS Mark II ceramics was higher than SBS of IPS emax CAD ceramics. SBS of Blugloo and Assure Plus for both VITABLOCS Mark II and for IPS emax CAD ceramics were higher than Transbond XT. SBS of metal brackets bonded to two different ceramic surfaces using three different adhesive systems were higher than the clinically accepted bond strength.

Background and objective: The study aims to assess the correlation between degree of monomer conversion (DC) and shear bond strength (SBS) of the different adhesives. The objective of the present study was to determine the efficiency of four orthodontic adhesives regarding shear bond strength (SBS), debonding characters and degree of conversion (DC) and to correlate SBS to the DC. Methods: Forty human upper first premolars, divided into four Groups (n = 10) were bonded with metal brackets using four different adhesives. Brackets were debonded in shear on an Instron universal testing machine with a crosshead speed of 1 mm per minute. The mode of bond failure was determined by the adhesive remnant index (ARI) index and the DC was determined by Fourier transform infrared spectroscopy (FTIR) analysis. Result: There was a statistically significant difference between the SBS of only Transbond XT and Orthobond plus color change adhesive while the two remaining adhesives showed no significant difference. All groups of adhesives showed a cohesive type of bond failure according to the ARI results. A statistically significant lower percentage of DC was noted for Orthobond plus (63 %) than Transbond XT (70.2 %) but it was within the accepted range reported in the literature (55-75%). Pearson’s correlation was significantly positive between SBS and DC for Smart Ortho, Heliosit Orthodontic and Orthobond Plus adhesives and insignificantly positive for Transbond XT. Conclusion: Within the limitations of this in vitro study it can be concluded that the Transbond plus color change has significantly higher fluoride release as well as recharge properties when compared to other ortho-adhesive materials. Keywords: Orthodontic Adhesive, Shear Bond Strength, Degree of conversion

Background Selection of the appropriate curing time and light direction may enable the appropriate shear bond strength to be obtained and avoid enamel fracture during debonding. Aims To determine the effects of different curing times and light directions on the shear bond strengths of ceramic and stainless steel brackets. Method Ninety-two recently extracted, upper premolars were randomly assigned to six groups. Either stainless steel or ceramic brackets were bonded to the buccal surfaces of the teeth. Group 1, stainless steel brackets cured for 40 seconds from buccal surface; Group II, stainless steel brackets cured for 40 seconds from palatal surface; Group III, stainless steel brackets cured for 80 seconds from palatal surface; Group IV, ceramic brackets cured for 40 seconds from the buccal surface; Group V, ceramic brackets cured for 40 seconds from the palatal surface; Group VI, ceramic brackets cured for 80 seconds from the palatal surface. The shear bond strength was measured with a universal testing machine and the resin remaining after debonding scored with the Adhesive Remnant Index (ARI). The data were analysed with the one-way ANOVA, Tukey’s HSD test and the Kruskal-Wallis test. Associations between the ARI and shear bond strength were determined with Pearson’s correlation coefficient. Results Group IV (ceramic brackets cured for 40 seconds from buccal surface) had the highest shear bond strength (21.26 MPa) and Group II (metal brackets cured for 40 seconds from palatal surface) had the lowest shear bond strength (6.95 MPa).There was no significant difference in ARI scores among the groups. The association between the ARI scores and bond strength values was not statistically significant. Conclusions Curing from the buccal surface for 40 seconds gave unacceptably high shear bond strength values for both stainless steel and ceramic brackets. Lower shear bond strengths occurred when the light was directed from the palatal surface, but a shorter curing time is more likely to be preferred by clinicians. Future studies should investigate the possibility of reducing the curing time for both brackets.

Objectives: The objective of the present study was to evaluate and compare the bond strength of orthodontic brackets bonded to permanent teeth with a conventional acid-etching and self-etching primer systems. Also, the study aims to evaluate the mode of bond failure after debonding the brackets. Materials and Methods: It was an experimental study. Fifty extracted permanent premolars were collected, checked, and cleaned. Teeth were split equally into two groups, group A and B. Orthodontic brackets were bonded using conventional acid-etching and self-etching primer systems for group A and B, respectively. Shear bond strength (SBS) was measured with a universal testing machine, and the mode of bracket-adhesive failure was determined by using adhesive remnant index (ARI). Data were analyzed with a statistical software. Independent sample t-test was used to compare the SBS and Mann–Whitney U test was used to assess whether there is a significant difference of ARI score between the groups. Results: Although the SBS with self-etching primer was within clinically acceptable range, the overall mean SBS for group A (14.71 MPa) was significantly greater than group B (9.24 MPa) (P = 0.024). There was no significant difference in ARI scores between conventional acid-etching and self-etching groups (P = 0.801). Conclusion: The SBS of the conventional acid-etching was significantly higher than the self-etching primer. The SBS of self-etch was within the acceptable range to withstand the forces of mastication. The majority of the brackets recorded ARI score of 1 indicating a cohesive failure with no significant difference between acid-etch and self-etch groups.

Shear bond strength, adhesive remnant index, and anti-biofilm effects of a photoexcited modified orthodontic adhesive containing curcumin doped poly lactic-co-glycolic acid nanoparticles: An ex-vivo biofilm model of S. mutans on the enamel slab bonded brackets.

Objective: To investigate the effects of surface preparation with sodium hypochlorite (NaOCl) on bracket shear bond strength and amount of residual adhesive on primary and permanent teeth. Materials and Methods: 24 permanent premolars, 12 in each group (groups I and III), and 24 primary molars, 12 in each group (groups II and IV) were included. In group I and II, 37% phosphoric acid was applied to the tooth surfaces, without using any other agent. In Group III and IV, 5.25% NaOCl was first applied. Following washing and drying, surface roughening was performed with phosphoric acid. The shear bond strengths (SBS) of the brackets bonded to the tooth surfaces was measured. After debonding, the base of each bracket was examined for adhesive remnant index (ARI) scores. Results: There were no statistically significant differences in SBS values between primary and permanent teeth with and without preparation with NaOCl(P>0.05). Mean SBS(18.55±14.98 MPa) was higher in permanent premolars subjected to surface deproteinization with NaOCl (group III) when compared with other groups, but the difference was not significant. There was no significant difference in ARI scores between the groups. Conclusions: The bond strength of orthodontic brackets or the distribution of ARI scores were similar between groups with and without NaOCl pretreatment. Hence, it can be concluded that conventional bonding procedures applied without any additional preparation to primary teeth are sufficient and the debonding of brackets didn’t cause any harm to enamel surfaces.

Bonding procedures are time consuming and debonding of brackets is a common problem encountered in orthodontics. The purpose of this in vitro study was to evaluate the shear bond strength (SBS) with different enamel pretreatment (acid etching, air abrasion, and bur abrasion) to enhance the bonding performance. A total of 60 extracted premolars for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group I - conventional etching with 37% phosphoric acid; Group II - air abrasion with 50 μm aluminum oxide; and Group III - bur abrasion with diamond fissure (#330, MANI, Dia-Burs, New Jersey, USA). After storing the specimens for 24 h in distilled water at 37°C, SBS was measured with Universal testing machine (Lloyd Universal testing machine-Model No. L.R 100K, UK). The shear force at a crosshead speed of 1 mm/min was transmitted to brackets. The adhesive remnant index (ARIs) scores were recorded after bracket failure. Descriptive statistics, multiple comparisons of the SBS of different groups, were performed by analysis of variance. The Tukey's test was used to evaluate differences in ARI scores between groups. All statistical evaluations were calculated using the Statistical Package for Social Sciences Windows, release 10.0.0 (SPSS Inc., Chicago, Illinois, USA). The analysis of SBS variance (P < 0.01) and Chi-square test of ARIs scores (P < 0.01) revealed significant differences among three groups tested. The SBS in Group I (mean: 8.822 ± 0.92 MPa) and Group III (mean: 6.015 ± 0.87 MPa) was significantly higher than Group II (mean: 3.824 ± 0.57 MPa). The ARI was used to evaluate the residual adhesive on the enamel after bracket removal. The Tukey's test was used to evaluate differences in the ARI scores among the groups. The current findings indicate that enamel surface preparation using bur abrasion results in a significant higher than air abrasion; within the limitations of this study recommend bur abrasion as a viable alternative to acid etching.

Evaluation of the effect of different surface conditioning methods on shear bond strength of metal brackets bonded to aged composite restorations

To determine the influence of two adhesion boosters on shear bond strength and on the bond failure location of indirectly bonded brackets. Sixty bovine incisors were randomly divided into three groups (n = 20), and their buccal faces were etched using 37% phosphoric acid. In group 1 (control), brackets were indirectly bonded using only Sondhi adhesive. In groups 2 and 3, the adhesion boosters Enhance Adhesion Booster and Assure Universal Bonding Resin, respectively, were applied before bonding with Sondhi. Maximum bond strength was measured with a universal testing machine, and the location of bond failure was evaluated using the Adhesive Remnant Index (ARI). One-way analysis of variance followed by the Tukey test (P < .05) was used to compare the shear bond strength among groups, and the differences in ARI scores were evaluated using the Kruskal-Wallis test (P < .05). The Pearson correlation coefficient was calculated to determine whether there was any correlation between bond strength and ARI scores. The mean shear bond strength in group 3 was significantly higher (P < .01) than in the other groups. Evaluation of the locations of bond failure revealed differences (P < .05) among the three groups. There was a moderate correlation between bond strength and ARI scores within group 3 (r = 0.5860, P < .01). In vitro shear bond strength was acceptable in all groups. The use of the Assure adhesion booster significantly increased both the shear bond strength of indirectly bonded brackets and the amount of adhesive that remained on the enamel after bracket debonding.

Context:Effect of adhesion boosters on shear bond strength of orthodontic brackets.Aim:The aim is to evaluate the shear bond strength and adhesive remnant index (ARI) score of new brackets bonded to a debonded tooth surface with and without the use of adhesion boosters.Settings and Designs:In vitro comparative study.Materials and Methods:Adhesion boosters: Enhance LC (Reliance, Itasca III) All Bond 2 (Bisco, Schaumsburg) and the Composite adhesives Transbond XT (3M UNITEK) Enlight (ORMCO) were used in this study. One hundred and eight extracted maxillary first premolar teeth were bonded with light cure composite to etched tooth surface. The brackets were then debonded with debonding pliers after 1 week and it was polished with low speed tungston carbide bur and rubber cup. The teeth were divided into six groups and they were etched, washed, and dried again. New brackets were rebonded to the tooth surface using composites with or without adhesion boosters. Then, the shear bond strength value was calculated for each bracket with a universal testing machine. ARI scores were also evaluated.Statistical Analysis Used:One-way ANOVA and least significant difference post hoc test was used for the association between variables. Probability value (P < 0.05) was considered statistically significant.Results:The results showed a statistically significant difference between the groups with a P < 0.001. There was no significant difference in ARI scores between the groups (P = 0.15).Conclusions:Both the adhesion boosters significantly improved the shear bond strength of orthodontic brackets. There was no statistically significant difference in the ARI scores.

BACKGROUND:An ideal orthodontic adhesive should provide a bond strong enough to withstand the forces of orthodontic treatment and mastication without dislodging, while also being safe enough to prevent surface damage debonding. Shear bond strength (SBS) is a critical factor that determines the quality of bonding in orthodontics. Nanoparticle-enhanced adhesives have been reported to offer additional benefits such as antimicrobial properties and remineralization effects, making them worth investigating for their shear bond characteristics. Aim: This in vitro study aimed to evaluate and compare the SBS and Adhesive Remnant Index (ARI) scores of orthodontic adhesives containing copper-substituted hydroxyapatite (Cu-HA) nanoparticles with a conventional orthodontic adhesive.MATERIALS AND METHODS:Twenty-eight extracted human premolar teeth were randomly divided into two groups of 14. In Group 1, orthodontic brackets were bonded using Enlight adhesive mixed with Cu-HA nanoparticles, while Group 2 used conventional Enlight adhesive. SBS was measured using a Universal Testing Machine, and the debonded samples were evaluated for ARI scores under scanning electron microscopy (SEM). Statistical analyses were performed using independent t-tests for SBS comparison and Mann-Whitney U tests for ARI score differences. A P value < 0.05 was considered statistically significant.RESULTS:The group using Enlight adhesive with Cu nanoparticles exhibited a significantly higher mean SBS (9.03 ± 6.17 MPa) compared to the conventional adhesive group (5.51 ± 2.099 MPa, P = 0.003). The median ARI score for the Cu-HA nanoparticle group was 3, while the conventional group had a median ARI score of 2 (P = 0.022). Both SBS and ARI scores were significantly higher in the Cu-HA nanoparticle group.CONCLUSION:Copper-substituted hydroxyapatite nanoparticles enhance bond strength and adhesive retention, making them a promising alternative to conventional adhesives in orthodontics.CLINICAL RELEVANCE:The findings indicate that adhesives containing Cu-HA nanoparticles, especially when combined with the Enlight adhesive, offer superior bond strength and adhesive retention compared to conventional adhesives. This could lead to improved clinical outcomes in orthodontic bonding, potentially reducing bracket failure rates and enhancing treatment efficiency.