In vitro analysis of shear bond strength and adhesive remnant index of different metal brackets

Physical, mechanical and antibacterial properties of the orthodontic adhesive doped with S-TiO2

Orthodontic adhesive doped with sulfur-modified TiO2 promotes antibacterial effect. The objective of the study was to characterize the physical, mechanical and antibacterial properties of the orthodontic bracket adhesive, doped with modified titanium dioxide nanoparticles. Sulfur-doped TiO2 was synthetized and morphological topography was analyzed with TEM and SEM imaging. The catalytic performance during the degradation of rhodamine B was assessed. Nanomaterial was added at four concentration (1, 3, 6, and 10 wt%) to a commercial orthodontic adhesive. The shear bond strength and microhardness of a resin-based orthodontic adhesive containing S-TiO2 were evaluated. The inhibitory effect of the pure and doped adhesives against Escherichia coli and Streptococcus mutans was examined. As the results, the highest antimicrobial activity and good adhesive properties were noticed for light-cured orthodontic adhesive doped with 3% of S-TiO2. In this case, orthodontic adhesives with strong and long-lasting bactericidal properties can be created through the incorporation of modified TiO2 without negatively influencing microhardnesses, and bonding ability. White spot lesion and demineralization, which occurs very often in patients during orthodontic treatment, can be therefore minimized.

Effect of Different Desensitizer Treatments on the Shear Bond Strength of Orthodontic Metal Brackets Following In-Office Bleaching: An In Vitro Study

OBJECTIVE

 One of the adverse effects of in-office bleaching is tooth hypersensitivity, which could be neutralized with a desensitizing agent. In-office bleaching and the application of desensitizing agents will affect the morphology of the enamel surface. These morphological changes have potential effects on the shear bond strength (SBS) and bonding of orthodontic brackets. This study analyzed the effects of fluoride and nonfluoride desensitizing agents after in-office bleaching on the SBS of metal brackets with resin composite cementation.

MATERIALS AND METHODS

 Twenty-seven postextraction premolars (n = 27) were bleached with 37% hydrogen peroxide and then divided into three groups: control group (group 1), fluoride-based desensitizing agent (group 2), and nonfluoride-based desensitizing agent (group 3). After treatment, the brackets were bonded using Transbond, and then the SBS test was performed using a universal testing machine. The adhesive remnant index (ARI) was analyzed after the SBS test, whereas enamel morphological changes were observed under a scanning electron microscope. After this assessment, energy-dispersive X-ray spectroscopy was conducted to determine calcium and phosphorus elements in the enamel surface after treatments. SBS data were analyzed using the one-way analysis of variance, followed by the Tukey test, whereas ARI scores were subjected to the Kruskal-Wallis test and the Mann-Whitney test with a significance level of 5%.

RESULTS

 The SBS increased significantly in group 2 compared with groups 1 and 3 (p < 0.05). In group 2, an ARI of 2 (55.56%) was frequent, whereas in group 3, an ARI of 3 (55.56%) appeared most frequently.

CONCLUSION

 The application of the desensitizing agent fluoride after in-office bleaching increased the SBS and more adhesive remains on the tooth surface compared with that when nonfluoride desensitizing agents were applied on metal brackets with composite resin cementation.

Effect of Different Primers on the Shear Bond Strength of Orthodontic Brackets Bonded to Reinforced Polyetheretherketone (PEEK) Substrate

This in vitro study assessed the effect of different primers on the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets bonded to reinforced polyetheretherketone (PEEK) substrate. A total of 40 specimens were randomly distributed to two groups based on the primer used for orthodontic bonding: group 1 (control)-Transbond XT adhesive with Visio.link primer and group 2 (test)-orthodontic adhesive (Transbond XT) with traditional orthodontic primer. After bonding, specimens were thermocycled followed by SBS testing and ARI scoring of debonded specimens. Data were analyzed using the unpaired independent t-test and the Chi-square test. Group 1 specimens showed significantly higher SBS values (21.38 ± 1.48 MPa) compared to group 2 specimens (18.63 ± 1.29 MPa) (p < 0.0001). Adhesive remnant index scores showed no significant variations in bond failure modes and distributions between groups. The SBS obtained by the tested primers exceeded the clinically recommended value. Consequently, there is a comparable clinical application for both tested primers in orthodontic bonding, especially the traditional orthodontic primer, where the availability of Visio.link in clinical practice is not ensured.

Does the use of universal adhesive systems improve the durability of the bond strength of orthodontic brackets to enamel?

Background

Universal adhesive systems used for restorative clinical procedures are like orthodontics and may be a viable option. This study evaluated the effectiveness of universal adhesive systems in enhancing the durability of the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets to enamel.

Material and Methods

100 bovine incisors were divided into five groups (n=20), according to the applied adhesive systems: Primer Transbond XT; Ambar; Ambar Universal; Single Bond Universal; Adper Single Bond 2. Bracket from each tooth were submitted to SBS test after 24 hours, and 12 months later. The amount of remaining adhesive was evaluated through ARI.

Results

After 24 hours, there was no difference in BS between the control and the other groups (p>0.05). However, there were difference between TOTALETCHING1 group and the Ambar Universal (p=0.015) and Single Bond Universal groups (p=0.011). After 12 months, Primer Transbond XT, Ambar, Ambar Universal and Adper Single Bond 2 showed no differences in the SBS (p>0.05). Nonetheless, Single Bond Universal presented superior result when compared to Primer Transbond XT (p=0.046) and Ambar (p=0.011) groups. The SBS of all groups reduced significantly after 12 months (p<0.05). There was no difference between ARI scores in each individually assessed group (p>0.05), for both periods. Following 24 hours, a difference was observed between the groups (p=0.043), fact that didn't occur after 12 months (p=0.109).

Conclusions

Adhesive systems, such as Ambar Universal and Single Bond Universal are efficient in bonding orthodontic brackets to enamel when associated with Transbond XT adhesive paste. Key words:Bond strength; Primer Transbond XT, orthodontic brackets, adhesive systems.

A novel orthodontic adhesive containing zinc-doped phosphate-based glass for preventing white spot lesions

OBJECTIVES

This study aimed at demonstrating the remineralization effect of the enamel around the brackets to aid reduction in white spot lesions (WSLs) with use of zinc-doped phosphate-based glass (Zn-PBG) containing orthodontic adhesives.

METHODS

Zn-PBG powder was synthesized, and particle morphology, size, and density were evaluated. Orthodontic adhesives with increasing loading percentage of Zn-PBG powder were prepared: ZnPG3 (3 wt.%), ZnPG6 (6 wt.%), and ZnPG9 (9 wt.%). Brackets were bonded on the etched enamel surface and stored in distilled water (DW) for 1 h. Following, Shear bond strength (SBS) along with adhesive remnant index were analyzed. The release of calcium (Ca), phosphorus (P), and zinc (Zn) from adhesive specimens in DW was evaluated after 7, 15 and 30 days of immersion. The remineralization effect was confirmed by microhardness and surface morphology analysis with scanning electron microscopy.

RESULTS

The SBS value was observed between 20 and 22 MPa on enamel surface. The concentration of Ca, P and Zn released in DW increased with loading percentage of Zn-PBG. The microhardness increased in the experimental groups after immersion in artificial saliva for 7 days. Apatite-like crystal formation was observed after 30 days in the ZnPG 9 group.

CONCLUSIONS

The orthodontic adhesive containing Zn-PBG with an optimal SBS performance has an enamel remineralization effect, and therefore can aid in prevention of WSLs.

CLINICAL SIGNIFICANCE

The orthodontic adhesive containing Zn-PBG is clinically advantageous as it can promote remineralization and resist the formation of WSLs that may occur during orthodontic therapy.

Bond Strength and Surface Roughness of Two Ceramics After Metal Bracket Debonding

Objective

The aims of this study were to compare the bond strength between metallic brackets and two different glass ceramics and to evaluate the ceramic surface roughness after different finishing protocols.

Methods

The surface roughness of lithium disilicate and resin matrix ceramic samples was measured (initial). All samples were treated with hydrofluoric acid and silane and bonded to metallic brackets with orthodontic cement adhesive. Shear bond strength tests were performed using a universal testing machine (n=12). The surface roughness was measured again (intermediate, n=6) after removing the remaining cement adhesive from the ceramic surfaces with a diamond or 24-blade bur after polishing the ceramic surfaces (final, n=6).

Results

The resin matrix ceramic had the highest bond strength. The rotatory instrument used for the removal of cement adhesive did not affect the surface roughness of the resin matrix ceramic or lithium disilicate (p=0.985 and p=0.504, respectively), but did affect the evaluation time (p<0.001) for both restorative materials. The intermediate roughness was the highest. For the resin matrix ceramic, polishing promoted a final surface roughness similar to the initial condition; however, changes in the surface shape of this ceramic could be visibly observed when using a 24-blade bur.

Conclusion

The bond strength of metallic brackets bonded on resin-matrix ceramics is higher than bonding on lithium disilicate. The use of diamond burs for the removal of the remaining adhesive from the resin matrix ceramics is highly recommended.

Effect of incorporating silica-hydroxyapatite-silver hybrid nanoparticles into the resin-modified glass ionomer on the adhesive remnant index score and shear bond strength of orthodontic metal brackets: An in vitro study

OBJECTIVES

This study aimed to assess the effect of addition of silica-hydroxyapatite-silver (Si-HA-Ag) hybrid nanoparticles to light-cure glass ionomer (GI) on shear bond strength (SBS) of metal brackets bonded with this adhesive and the adhesive remnant index (ARI) score.

MATERIAL AND METHODS

In this in vitro experimental study, 50 sound extracted premolars were assigned to 5 groups (n=10) for orthodontic metal bracket bonding with BracePaste® composite, Fuji ORTHO™ pure resin modified GI (RMGI), and RMGI reinforced with 2wt%, 5wt% and 10wt% Si-HA-Ag nanoparticles. The SBS of brackets was measured by a universal testing machine. Debonded specimens were inspected under a stereomicroscope at×10 magnification to determine the ARI score. Data were analyzed by one-way ANOVA, Scheffe test, Chi-square test, and Fisher's exact test (alpha=0.05).

RESULTS

The maximum mean SBS was recorded in BracePaste® composite followed by 2% RMGI, 0% RMGI, 5% RMGI and 10% RMGI. Only the difference between the BracePaste® composite and 10% RMGI was significant in this regard (P=0.006). The groups were not significantly different regarding the ARI scores (P=0.665). All the SBS values were within the clinically acceptable range.

CONCLUSION

Addition of 2wt% and 5wt% Si-HA-Ag hybrid nanoparticles to RMGI as orthodontic adhesive caused no significant change in SBS of orthodontic metal brackets while addition of 10wt% hybrid nanoparticles significantly decreased the SBS. Nonetheless, all the SBS values were within the clinically acceptable range. Addition of hybrid nanoparticles had no significant effect on the ARI score.

Bonding Surface Designs in Fixed Orthodontic Attachments

Fixed orthodontic attachments/appliances work as a medium to transfer the force applied to the teeth. In bonded types, several factors affect the attachment bond strength and their clinical success. The primary approach for increasing the bond strength focused on altering the time and concentration of acid etching; however, the results showed that these changes might increase susceptibility to enamel decalcification. The bonding mechanism of orthodontic attachments may be chemical, mechanical, or a combination of both. Most attachment bonding surfaces (ABSs) have no chemical bond to resin composites. Hence, mechanical retention plays a major role. Developing more bonding surfaces by increasing the macroscopic size of the attachments has esthetic and hygienic limitations, so the ABS design plays a more important role in maintaining and improving the bond strength. In this research, different ABS designs are reviewed and categorized according to manufacturing methods and their features.

Adhesive Precoated Bracket: Is It Worth Using? Long-term Shear Bond Strength: An In Vitro Study

OBJECTIVES

 The objectives of this study were to compare the long-term shear bond strength of conventional adhesive on metal brackets with that of adhesive precoated brackets in vitro and to evaluate the amount of adhesive remnant on the tooth surface after debonding.

MATERIALS AND METHODS

 A total of 90 maxillary permanent premolars were randomly divided into two groups. The samples in the first group were bonded with metal brackets using Transbond PLUS Color Change Adhesive (TP), and the samples in the second group were bonded with Flash-Free adhesive precoated brackets (APC FF). The bonding techniques were performed, according to the manufacturer's instructions. The samples from each group were randomly divided into three subgroups with different thermal cycles (n = 15). The shear bond strength (SBS) and adhesive remnant index (ARI) were measured and calculated.

STATISTICAL ANALYSIS

 Two-way ANOVA and Chi-square test were used to analyze the differences in the SBS and ARI between the groups, respectively.

RESULTS

 The means of the SBS of the APC FF subgroups were significantly lower than those of the TP subgroups, except in the 10,000 thermocycle subgroups. Chi-square test showed no statistically significant differences between the groups and subgroups. An ARI score of 1 was the predominant score in both groups.

CONCLUSIONS

 This study found that the SBS of APC FF gradually increased with time and thermal aging did not affect the failure pattern.

Physical/Mechanical and Antibacterial Properties of Orthodontic Adhesives Containing Calcium Phosphate and Nisin

Enamel demineralization around orthodontic adhesive is a common esthetic concern during orthodontic treatment. The aim of this study was to prepare orthodontic adhesives containing monocalcium phosphate monohydrate (MCPM) and nisin to enable mineralizing and antibacterial actions. The physicomechanical properties and the inhibition of S. mutans growth of the adhesives with added MCPM (5, 10 wt %) and nisin (5, 10 wt %) were examined. Transbond XT (Trans) was used as the commercial comparison. The adhesive containing a low level of MCPM showed significantly higher monomer conversion (42–62%) than Trans (38%) (p < 0.05). Materials with additives showed lower monomer conversion (p < 0.05), biaxial flexural strength (p < 0.05), and shear bond strength to enamel than those of a control. Additives increased water sorption and solubility of the experimental materials. The addition of MCPM encouraged Ca and P ion release, and the precipitation of calcium phosphate at the bonding interface. The growth of S. mutans in all the groups was comparable (p > 0.05). In conclusion, experimental orthodontic adhesives with additives showed comparable conversion but lesser mechanical properties than the commercial material. The materials showed no antibacterial action, but exhibited ion release and calcium phosphate precipitation. These properties may promote remineralization of the demineralized enamel.

Disinfection of radicular dentin using Riboflavin, Rose Bengal, Curcumin, and Porfimer sodium on extrusion bond strength of fiber post to radicular dentin

AIM

To assess the influence of different photosensitizers activated by PDT as a disinfectant in comparison to conventional sodium hypochlorite (NaOCl) on the EBS (extrusion bond strength) of FRCP with radicular dentin.

METHODS

A total of fifty single-rooted human maxillary central incisors with fully developed apices were selected. Endodontic treatment of samples was performed using 10K file to obtain patency than sequentially with a 25K file followed by rotary pro tapers till F2 with constant irrigation. The canal was dried and obturated with corresponding gutta-percha and sealer. A Peso reamer was employed to prepare post space. Based on canal disinfection regimes, samples were divided into five groups. Group 1 Riboflavin (RF)+17%EDTA, group 2 Rose bengal (RB) +17%EDTA, group 3 Curcumin CP +17%EDTA, group 4 Porfimer sodium, Photofrin (PS) +17%EDTA and group 5 2.25% NaOCl +17% EDTA (control). Following disinfection, the canal space of all specimens was dried followed by FRCP cementation. Specimens were placed on a Universal testing machine (UTM) for EBS. The type of bond failure was evaluated using a stereomicroscope. ANOVA and Tukey multiple comparison tests were used to compare means.

RESULTS

The highest EBS was shown by group 1 canal disinfected with riboflavin (RF) and 17% EDTA at all three levels. The lowest EBS was displayed in group 5 canal cleaned with 2.25% NaOCl and 17% EDTA. Intragroup assessment disclosed a decrease in EBS from cervical one-third to apical one-third in all experimental groups. Intergroup comparison revealed group 4 using PS and 17% EDTA and group 5 canal disinfected with 2.25% NaOCl and 17% EDTA at all three levels of root structure coronal, middle, and apical exhibited comparable EBS (p>0.05).

CONCLUSION

Root canal dentin treated with different PS (RF, RB, CP) has the potential to be used as canal disinfection as it demonstrates better EBS than the conventional disinfecting regime (2.25% NaOCl +17% EDTA). PS and 17% EDTA as a canal disinfectant need further investigation.

Influence of methylthioninium chloride, curcumin and Er, Cr: YSGG on caries affected dentin bonded to bioactive and conventional bulk fill dental restorative material

AIM

The study aimed to determine the influence of Er, Cr: YSGG (ECL), methylene blue photosensitizer (MBP), and curcumin photosensitizer (CP) disinfection on CAD and its bond strength and microleakage to bioactive (BA) and multicore (MC) bulk-fill composite.

MATERIALS AND METHODS

Sixty carious mandibular molars were collected based on the criteria of ICDAS Code 6 (International Caries Detection and Assessment system). Specimens were embedded in polyvinyl pipes up to CEJ and subjected to preparation of standard class II cavity leaving CAD in situ for bonding. All samples were randomly assigned to eight groups based on disinfection regimes and type of bulk-fill material. Samples in group 5 and 6 didn't undergo any disinfection; group 1: ECL + BA, group 2: ECL+ MC; group 3 MBP + BA, group 4: MBP + MC; group 5: Conventional Etch and Rinse + BA (Control), group 6 Conventional Etch and Rinse + MC (Control); group 7: CP +BA and group 8 CP+MC. Specimens were tested for SBS using a universal testing machine and the debonded surfaces were evaluated under a stereomicroscope to determine modes of failure. A dye penetration test was performed for microleakage assessment. For intergroup comparison test analysis of variance (ANOVA) was performed using means and standard deviation from each group. Tukey HSD was used for multiple group comparison tests. The level of significance was established at p < 0.05.

RESULTS

The maximum mean bond strength was shown by group 6 (18.96 ± 0.31 MPa) conventional etch and rinse+ MC (control). Whereas, the minimum SBS was recorded in specimens of group 7 CP +BA (13.04 ± 0.81 MPa). SBS values among group 3 (14.05 ± 0.10 MPa- MBP+BA), group 4 (13.66 ± 0.39- MBP+MC) group 7 (13.04 ± 0.81 MPa- CP +BA and group 8 (14.21 ± 0.59 MPa- CP+MC) were found to be comparable (p>0.05). There was no statistically significant difference among the study groups concerning microleakage (p >0.05).

CONCLUSION

CAD treated with ECL for the adhesive bonding of BA and conventional bulk-fill composite MC has shown potential to be used clinically. Moreover, MBP and CP for conditioning of CAD need further investigation.

Shear bond strength of metallic brackets bonded to enamel pretreated with Er,Cr:YSGG LASER and CPP-ACP

Background

Increased risk of enamel demineralization during and after orthodontic treatment raises the demand for better preventive measures including combinations of laser, CPP-ACP, and fluoride. The combination of Er,Cr:YSGG laser with CPP-ACP was proved to have a synergetic effect compared to each of them alone. Shear bond strength (SBS) of orthodontic brackets bonded to the enamel surface after being treated with preventive measures is critical. The aim of this study was to compare the SBS and failure mode of metallic brackets bonded to teeth with no pretreatment and pretreated enamel surface, either with Er,Cr:YSGG laser alone or combined with CPP-ACP.

Methods

Sixty sound extracted human premolar teeth were allocated randomly to 3 groups: In Group 1 (control), teeth were etched and bonded directly; in Group 2, laser pretreatment of the enamel surface was done followed by etching and bonding as in the control group; in Group 3, the enamel surface was lased then CPP-ACP was applied according to the manufacturer instructions, etched and bonded. SBS and Adhesive remnant index (ARI) were evaluated.

Results

No significant differences were found between the 3 groups neither in the SBS nor in the ARI scores.

Conclusions

The use of combined Er,Cr:YSGG laser with CPP-ACP as a preventive measure before bonding orthodontic brackets does not endanger the bracket’s bonding strength.

Influence of Photodynamic therapy and different gingival retraction agents on bond integrity of composite to dentin

AIM

The present study was undertaken to evaluate the influence of gingival retraction agents (Expasyl and Viscostat) and different conditioning methods (Total-etch, Self-etch, and PDT) on bond integrity of composite to dentin.

MATERIAL AND METHODS

One hundred and eighty, third molars were collected cleaned and disinfected in thymol solution. The specimens were rooted vertically up to cementoenamel junction within polyvinyl cylinders (PVC). Based on gingival retraction materials samples were divided into three groups (n = 60). Group A: dentin applied with Expasyl; Group B: Viscostat was applied on dentin and Group C: Control. Dentin surface was treated with different surface conditioners. Etch and rinse, PDT MBP, and Two-step self-etch. A bonding agent was applied and composite buildup was done. Samples were placed in the universal testing machine for SBS. Bond failure was assessed using a stereomicroscope. Analysis of variance (ANOVA) and Tukey's post hoc test compared the means and standard deviations (SD) after SBS testing (p = 0.05).

RESULTS

The highest score of bond strength was exhibited by group C1 (21.14 ± 1.05 MPa-Etch & rinse + Tetric-N- Bond) whereas group C2 (12.15 ± 0.28 -PDT MBPS + Tetric-N-Bond, No treatment group) demonstrated the lowest SBS. Based on the application of haemostatic agent, bond values among subgroups A1 (18.75 ± 1.05 MPa - Expasyl + Etch & rinse + Tetric-N-bond) and B1 (17.84 ± 0.11 MPa -Viscostat + Etch & rinse + Tetric-N-Bond) was comparable (p>0.05). Based on the conditioning methods, bond scores among groups C1 (21.14 ± 1.05 MPa -Etch & rinse + Tetric-N- Bond) and C3 (19.05 ± 1.28 MPa -Clearfill SE) were comparable (p >0.05).

CONCLUSION

Viscostat and Expasyl result in compromised bond integrity of composite restoration to dentin in etch and rinse and self-etch group compared to no treatment group. However, the pre-application of Viscostat and Expasyl on dentin conditioned with PDT improved bond integrity of composite resin.

Shear bond strength of APC Plus adhesive coated appliance system to enamel in wet and dry conditions: An in vitro study

OBJECTIVE

It is claimed that a hydrophilic primer, called the moisture insensitive primer (MIP), can be used with both dry and wet enamel surfaces. This study sought to assess the shear bond strength (SBS) of APC Plus adhesive coated appliance system to enamel using MIP in wet and dry conditions.

MATERIALS AND METHODS

This in vitro experimental study evaluated 24 extracted maxillary premolars with intact buccal enamel. The teeth were randomly divided into two groups (n=12), and APC Plus premolar brackets were bonded to their buccal surface using moisture insensitive primer (MIP) under wet and dry enamel conditions. The SBS values were measured by a universal testing machine. The adhesive remnant index (ARI) score was also determined under a stereomicroscope. Data were analyzed using t-test and Mann-Whitney test at P<0.05 level of significance.

RESULTS

The SBS in wet condition was significantly lower than that in dry condition (mean value of 18.37MPa versus 25.5MPa, P<0.001). The two groups had no significant difference regarding the ARI scores (P>0.05). However, in both groups, less adhesive was left on the tooth surface. This suggests that bond failure occurred at the adhesive-enamel interface.

CONCLUSIONS

APC Plus adhesive coated appliance system in combination with hydrophilic MIP can be effective in clinical conditions with high risk of moisture contamination.

Influence of fractional carbon-dioxide laser in comparison to ErCr-YSGG on the dentin bond integrity of bioactive materials

Objective:

The aim was to assess the influence of Er, Cr: YSGG laser (ECL) and fractional carbon dioxide laser (FCL) on the shear bond strength (SBS) and microleakage of bioactive restorative material to dentin.

Methods:

The study was performed in King Saud university in the month of June-July 2019. One hundred and twenty permanent teeth were vertically placed in acrylic resin. Based on the type of surface treatment regime (n=40), samples were divided into three groups. Group-I samples were surface conditioned with total etch and rinse (TE); Group-2 samples were surface treated with Er, Cr: YSGG laser (ECL) and Group-3 specimens were conditioned with fractional carbon dioxide laser (FCL). Surface treatment of dentin was followed by type of bulk fill resin (BFR) application. Tetric-N-Ceram was bonded to dentin conditioned with TE (n=20), FCL (n=20) and ECL (n=20). Similarly, bioactive material (BAM) was also bonded to conditioned surface (n=60). Samples (n=10) among each group were placed in a Universal testing machine. For microleakage testing 5 pairs of samples from each group (n=10) were placed in solution of 2% methylene blue for 24h Fracture analysis was performed using stereomicroscope at 40x magnification. Descriptive statistics i.e., means and standard for SBS and microleakage were compared using analysis of variance (ANOVA) and Tukey’s post hoc test at a significance level of (p < 0.05)

Results:

The highest SBS scores were displayed by TE-BFR (Bulk filled resin) (19.21 ± 0.925 Mpa) and the lowest shear bond scores were presented by FCL-BFR (11.06±1.611 Mpa). The lowest microleakage scores were exhibited by group ECL-BFR (24.11±13.01nm). Similarly, the highest microleakage score was displayed in group FCL-BAM (42.18±16.32 nm). Admixed failure was pertinent in groups conditioned by ECL. Moreover, groups conditioned with FCL adhesive type of failure was found in abundance.

Conclusions:

ECL has a potential to be used as an alternate to total etch and rinse for conditioning of dentin when bonded to bioactive materials.

Effect of Fluoride Releasing Bonding Materials on Shear Bond Strength of Orthodontic Brackets

Objective

The aim of the present study was to compare the shear bond strength (SBS) of three different fluoride-releasing bonding agents with a conventional adhesive system.

Methods

Eighty-four extracted human premolar teeth were separated into four groups and embedded in acrylic molds consisting of 21 teeth in each group. Brackets were bonded with Transbond XT in group 1, Clearfil SE Protect Bond in group 2, LED Proseal in group 3, and Opalseal in group 4. After bracket bonding, the teeth were thermocycled 1000 times. SBS test was performed, and Adhesive Remnant Index (ARI) scores of the groups were assessed.

Results

One-way analysis of variance test was used to compare the significant differences between the groups. Chi-square and Fisher's exact tests were used to evaluate ARI scores. The Opalseal group showed the highest bond strength, but there was no statistically significant difference between the groups in SBS values (p=0.067). The results of ARI scores were statistically significant.

Conclusions

All bonding materials used in the study showed clinically sufficient bond strengths.

Effect of Yd:YAG laser irradiation on the shear bond strength of orthodontic metal brackets

Objective:

The purpose of this study was to evaluate the effect of the Yd:YAG laser irradiation on orthodontic bracket base surface. Shear bond strength (SBS) values and sites of the bonding failure interfaces were quantified.

Methods:

Brackets were divided into two groups: OP (One Piece - integral sandblast base) and OPL (One Piece - laser irradiation). The brackets were randomly bonded on an intact enamel surface of 40 bovine incisors. The SBS tests were carry out using a universal test machine. A stereomicroscopy was used to evaluate the adhesive remnant index (ARI), and surface characterization was performed by scanning electron microscopy (SEM). Student’s t-test was used to compare the SBS between the two groups (p< 0.05). Frequencies and chi-square analysis were applied to evaluate the ARI scores.

Results:

OPL group showed higher value (p< 0.001) of SBS than OP group (43.95 MPa and 34.81 MPa, respectively). ARI showed significant difference (p< 0.001) between OPL group (ARI 0 = 100%) and OP group (ARI 0 = 15%). SEM showed a higher affinity between the adhesive and the irradiated laser base surface.

Conclusions:

Yd:YAG laser irradiation on bracket base increased SBS values, showing that bonding failure occurs at the enamel/adhesive interface. Laser-etched bracket base may be used instead of conventional bases in cases where higher adhesion is required, reducing bracket-bonding failure.

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

BACKGROUND

Potential complications during fixed orthodontic procedures are white spot lesions (WSLs) and tooth decay. This study evaluated the anti-biofilm activity of an orthodontic adhesive (OA) incorporating curcumin (Cur) doped Poly lactic-co-glycolic acid nanoparticles (Cur-PLGA-NPs), which can have the highest concentration of Cur-PLGA-NPs and shear bond strength (SBS) value simultaneously, against cariogenic bacteria i.e., Streptococcus mutans.

MATERIALS AND METHODS

Following synthesis and confirmation of Cur-PLGA-NPs, SBS and adhesive remnant index (ARI) of the modified orthodontic adhesives (MOA) containing Cur-PLGA-NPs (3, 5, 7, and 10 % wt.) were measured using universal testing machine and stereomicroscope, respectively. After artificial aging (continuously rinsed up to 180 days), the residual anti-biofilm ability of MOA which can have the highest concentration of Cur-PLGA-NPs and SBS value simultaneously were determined by anti-biofilm assay following photoexcited enamel slab bonded brackets by MOA containing Cur-PLGA-NPs against S. mutans biofilms using crystal violet assay.

RESULTS

Adhesive with 7 % wt. Cur-PLGA-NPs revealed the highest concentration of Cur-PLGA-NPs and SBS value (16.19 ± 2.69 MPa, P < 0.05) simultaneously. No statistically significant difference in ARI scores was observed between the MOA and control (Transbond XT without the Cur-PLGA-NPs). On days 15, 30, 60, 90 and 120 there was a considerable decrease in optical density (OD) of preformed S. mutans biofilms on photoexcited enamel slab bonded brackets using MOA containing 7 % wt. Cur-PLGA-NPs, to 94.1 %, 79.6 %, 69.6 %, 69.4 %, and, 55.1 % respectively in comparison to the control group (all, P < 0.05). From days 150 onwards, microbial biofilm formation was progressively increased on enamel slab bonded brackets using MOA containing 7 % wt. Cur-PLGA-NPs compared to the control group (OA). Although chlorhexidine (2 %; as positive control) showed significant activity against pre-formed S. mutans biofilms on enamel slab bonded brackets using OA (99.1 % biofilm reduction; P = 0.001), its activity was slightly higher but not significant than photoexcited enamel slab bonded brackets using MOA containing 7 % wt. Cur-PLGA-NPs on the days 15 and 30 (both, P > 0.05).

CONCLUSIONS

The 7 % wt. Cur-PLGA-NPs can serve as an orthodontic adhesive antimicrobial additive as exposure to blue laser provides an acceptable antimicrobial effect against cariogenic bacteria for a considerable time.

Priming and bonding metal, ceramic and polycarbonate brackets

Objective: To investigate if primers can be used to modify bonding characteristics of orthodontic brackets.

Materials and methods: Stainless steel, zirconia-alumina ceramic and polycarbonate brackets were bonded to enamel with and without universal and bracket material specific primers on the bracket base. Orthodontic adhesive cement (Transbond™XT) was used for bonding. The primers in each group (n = 10) were silane based (RelyX™ Ceramic Primer) and universal primer (Monobond Plus) for ceramic and metal brackets, and adhesive resin (Adper™ Scotchbond™ Multi-Purpose Adhesive) and composite primer (GC Composite Primer) for polycarbonate brackets. Controls with no primer were used for all bracket types. Teeth with bonded brackets were stored in distilled water in 37 °C for 7 days and debonded with static shear loading. Debonding forces were recorded and analyzed with ANOVA. Adhesive remnant index (ARI) was determined and enamel damage examined.

Results: The bond strength without primers was 8.14 MPa (±1.49) for metal, 21.9 MPa (±3.55) for ceramic and 10.47 MPa (±2.11) for polycarbonate brackets (p < .05). Using silane as primer increased the bond strength of ceramic brackets significantly to 26.45 MPa (±5.00) (p < .05). ARI-scores were mostly 2–3 (>50% of the adhesive left on the enamel after debonding), except with silane and ceramic brackets, ARI-score was mostly 0–1 (>50% of the adhesive left on the bracket). Debonding caused fractured enamel in four specimens with ceramic brackets.

Conclusions: Bond strength was highest for ceramic brackets. Silane primer increased bond strength when used with ceramic brackets leading to enamel fractures, but otherwise primers had only minor effect on the bond strength values.

Effect of mangosteen peel extract as an antioxidant agent on the shear bond strength of orthodontic brackets bonded to bleached teeth

Introduction:

The number of patients who seek orthodontic treatment that may have a history of tooth bleaching is increasing over the time. Bleaching may influence the decrease of the bond strength of orthodontic brackets.

Objective:

To determine and prove the effect of mangosteen peel (MP) extract to reverse the reduced shear bond strength (SBS) of orthodontic brackets after bleaching.

Methods:

A total of 150 maxillary first premolar teeth were randomly divided into 6 experimental groups as follow (n=25): negative-control (N: no bleaching), positive-control (P: bleaching + no treatment), and the treatment groups (bleaching + 10% sodium ascorbate (SA), 10% (MP-10), 20% (MP-20) and 40% (MP-40) MP extract gel). After treatment, the brackets were bonded with the resin-modified glass ionomer cement, SBS testing was performed using universal testing machine, and the adhesive remnant index (ARI) was examined using stereoscopic microscope after debonding. The SBS data were analyzed by analysis of variance (Anova) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed.

Result:

There was significant SBS difference (p< 0.001) between various groups. The group without bleaching showed significantly higher SBS (8.19 ± 2.26 MPa) compared to others, while SBS in the group treated with 40% MP gel was significantly higher (7.93 ± 1.92 MPa) than other groups treated with antioxidants. The failure of orthodontic brackets bonded after bleaching and treatment using MP extract occurred at the enamel-adhesive interface.

Conclusion:

The application of MP extract as an antioxidant after bleaching was effective in reversing the reduced shear bond strength of orthodontic brackets after bleaching.