Metal Orthodontic Brackets Research Articles

In-vitro comparison of bonding time and strength of adhesive pre-coated and standard metal orthodontic brackets

To compare the shear bond strength and bond time of 3M Unitek's APC (Adehesive Pre-Coated) Flash-Free™system applied to metal brackets. An in vitro study was performed on 40 extracted sound human premolar teeth randomly divided into two groups (20 per group) bonded either with Adhesive Pre-Coated Flash-Free metal brackets or metal brackets coated manually with Transbond XT™ light-cure adhesive. Bonding time was measured using a stopwatch. Thermoycling was performed on the samples (500 cycles) to simulate the oral environment between baths of 5°C and 55°C distilled water. Debonding shear bond strength measurements were performed in an Instron universal testing machine. The APC Flash-Free group bonded in significantly (p<0.001) less time (mean 34.06s/tooth) than the manually coated group (mean 55.14s/tooth). Shear bond strength of the manually coated group was significantly (p<0.001) higher (mean 13.32 MPa) than the APC Flash-Free group (mean 10.95 MPa). The APC Flash-Free free system is efficient and allows for reduced chair time during the bonding appointment while attaining a mean shear bond strength of 10.95MPa, which is higher than the minimum shear bond strength of between 4MPa and 7MPa1

Ability of a Blue Hemoglobin-Based Liquid as a Novel Technology to Stain Initial Enamel Demineralization: A Proof-of-Concept in vitro Study

During orthodontic treatment, enamel demineralization can occur. Its early detection is the basis for efficient preventive measures to arrest or remineralize lesions. In the present study, the application of a novel blue hemoglobin-based liquid (BlueCheck) was evaluated as proof of concept for detection of artificially demineralized smooth surfaces. 60 samples from extracted human posterior teeth were randomly assigned to four groups (15 per group). In 30 of these samples (groups A and B), superficial enamel was removed to create a ground surface. On the surface of other 30 samples (group C and D), orthodontic metal brackets were bonded. On each surface, BC liquid was applied and rinsed with water after 3 min (baseline). All surfaces were checked by two independent observers for presence of blue areas. On each sample, one side was covered by nail varnish to protect this enamel part from demineralization. The samples were demineralized with lactic acid (pH 4.6) for 7 days (group A and C) and 14 days (group B and D), respectively. Mineral loss was determined using quantitative light-induced fluorescence after demineralization. BlueCheck dye was again applied on the samples and evaluated for presence of stained areas. Histological sections were prepared from randomly selected samples and lesion depth was measured. Kruskal-Wallis test was used for group comparison (α = 0.05). After demineralization, median ΔF value for all samples was −8.25% indicating the presence of an initial demineralization. The difference of ΔF values was not statistically significant between samples at 7 or 14 days of demineralization, nor for samples with and without orthodontic brackets (p = 0.13). At baseline, none of the sample surfaces showed discoloration, whereas a distinctive blue color was visible after demineralization in all samples exposed to acid-exposed areas, corresponding to 100% sensitivity. The internal control surfaces (without demineralization) did not show any staining, corresponding to 100% specificity. Histologically measured lesion depths ranged between 200 and 254 μm. In this in vitro study, staining of demineralized enamel surface areas were shown to be reliable. Based on our results, this easily applicable product seems useful to be an adjuvant method to clinical examination to monitor oral health during an orthodontic treatment on tooth surfaces after removal of dental biofilm.

COMPARSION OF THE SHEAR BOND STRENGTH OF CERAMIC BRACKETS BONDED TO PORCELAIN FUSED METAL CROWNS AND METAL FREE CERAMIC CROWNS WITH AND WITHOUT SILANE COUPLING AGENT- AN IN VITRO STUDY.

Aim-The aim of this study is to evaluate and compare the shear bond strength of ceramic brackets bonded to porcelain fused metal crowns and metal free ceramic crowns with and without silane coupling agent.Material and Method: 40 metal free zirconia crowns and 40 PFM crowns were fabricated with glazed surfaces according to the manufacturer's instructions for the study purpose.The samples were divided in two groups A and B and each group was subdivided into two subgroups (A1, A2) and (B1, B2) Sub-Group A1 and A2: Twenty metal free ceramic crowns were etched with 9% buffered HF acid gel for 2 minutes,thoroughly washed and air dried.Relyx ceramic primer (silane coupling agent) was applied to the treated surface.Subgroup B1 and B2: 20 porcelain fused metal crowns were etched with 9% buffered HF acid gel for 2 minutes,thoroughly washed and air dried.Relyx ceramic primer (silane coupling agent) was applied to the treated surface. The shear bond strength of ceramic brackets bonded to porcelain fused metal crowns and metal free ceramic crowns with and without silane coupling agent. Statistical Analysis: ANOVA and Post hoc Tukey's test (HSD) tests were used for statistical analysis. Result: The result showed that group B1 demonstrate the maximum shear bond strength among all groups which is 9%HF +Relyx ceramic primer application on porcelain fused metal crowns (10.27+1.31Mpa) and has highly significant value.Whereas lowest shear bond strength belongs to group B2which is 9%HF and primer is not applied(5.4+0.73 Mpa).Conclusion: Hence it can be concluded that Relyx ceramic primer is more apropriate choice for bonding orthodontic metal brackets on PFM and zirconia surfaces with conventional bonding system.

The Effecacy of Different Surface Conditioning on Shear Bond Strength of Orthodontic Bracket Bonded to Lithium Disilcate Crowns; An in Vitro Study

Background and objective: Lithium disilicate widely used, and it is important to correctly bond orthodontic brackets to such materials. This study aimed to assess the impact of various types of surface conditioning methods on the shear bond strength (SBS) of orthodontic metal brackets to lithium disilicate crown. Materials and methods: In this in vitro study, 30 lithium disilicate specimens were prepared based on the type of surface conditioning into three surface conditioning groups (n=10 for each group). First group the semi-crowns surface was conditioned with 10% hydrofluoric acid etching, the second group was micro-etched with sandblast particles (50 um aluminum oxide particles) and the last group was conditioned with ultrasonic scaler. Valo light cure was utilized with 3200mw/cm2 light intensity. SBS was measured using a universal testing machine. The findings were statistically examined. Result: The results showed significant difference among the three groups where the sandblasting group had the higher mean of SBS, while the hydrofluoric acid etching group had the lower value and in between, the mean of ultra-sonic intermediate.      Conclusions:  Although the means of the three types of surface conditioning were significantly different, shear bond strength was positively affected by all of them and subsequently all types may be considered recommended techniques for reliable shear bond strength

Shear Bond Strength of Polypropylene Fiber in Orthodontic Adhesive on Glazed Monolithic Zirconia.

This study aims to compare shear bond strength (SBS) and mode of failure (MOF) between ceramic and metal orthodontic brackets on glazed monolithic zirconia using non-woven polypropylene fiber adhesive. Sixty glazed and sintered zirconia blocks were divided into six groups and attached with orthodontic brackets as follows: CS, ceramic bracket with silane; CB, ceramic bracket with bonding agent; CBS, ceramic bracket with bonding agent and silane; MS, metal bracket with silane; MB, metal bracket with bonding agent; and MBS, metal bracket with bonding agent and silane. There was a statistically significant difference in mean SBS values (p < 0.001). The CS group showed the highest SBS value (23.42 ± 3.88 MPa). On the other hand, the lowest was found in the MB group, which was not statistically different from the CB group (3.26 ± 0.76 and 5.09 ± 1.50 MPa, respectively). The MS, MBS, and CBS groups showed no statistical difference compared to each other (15.57 ± 4.01, 13.23 ± 5.47, and 12.77 ± 4.43 MPa, respectively). SBS is highest when a ceramic bracket with silane is bonded to glazed monolithic zirconia.

Shear bond strength of different bonding agents to orthodontic metal bracket and zirconia.

This study aimed to evaluate the shear bond strength (SBS) of four bonding agents used to bond metal brackets to zirconia under different storage conditions. Four bonding agents were used [FLC: (Fuji ORTHO LC), XT: (TransbondTM XT), RUC-SBU: (Rely XTM Ultimate Clicker Adhesive Resin Cement+Single Bond Universal), and RUC-GBU: (Rely XTM Ultimate Clicker Adhesive Resin Cement+Gluma Bond Universal)] to bond two types of metal brackets (PT/3M) to zirconia surfaces, and they were stored in water at 37ºC for 24 h or thermocycling for 3,000 cycles. The SBS data of RUC-SBU and RUC-GBU using PT brackets were significantly higher than those of 3M brackets before and after thermocycling. It could be concluded that RUC-SBU and RUC-GBU could offer sufficient bond strength between metal brackets and zirconia for the short term compared with FLC and XT. The design of brackets can significantly affect the bond strength to zirconia.

Comparison of shear bond strength of orthodontic metal brackets recylced using different methods: An in-vitro study

The aim of this study was to compare the effect of recycling orthodontic metal brackets by sandblasting with aluminum oxide particles of different sizes and by laser blow method after first and second rebonding /recycling. 120 human premolars extracted for orthodontic purpose were randomly divided into four groups. 40 MBT prescription Orthodontic metallic brackets were bonded on the buccal surface of the samples. Brackets were recycled by sandblasting with 3 different particles size and laser. Debonding of all brackets was performed using a universal testing machine and shear bond strength was determined. Brackets were examined under Field emission scanning electron microscope from each group at each level to compare the surface characteristic of new and rebonded brackets. Data were analyzed with paired test, ANOVA, and post hoc tests.The shear bond strength of group I (sandblasted with 25µm alumina) was significantly higher at the end of 1st recycling compared to group II(50 µm) and III(100 µm) but it was comparable to group IV(laser) at the end of 1st recycling. Group IV showed clinically significant higher shear bond strength compared to group II and III after 1st and 2nd recycling. The shear bond strength for group II and III (sandblasted with 50 and 110µm alumina) was significantly much lower after 2nd recycling as compared to new i.e., Control (p value&amp;#60;0.001⁎⁎⁎).25µm alumina sandblasting and Er-YAG laser blow method obtained better results after three successive recycling. Overall sandblasting emerged as the best method to recycle the orthodontic brackets.

A comparative study of shear bond strength of four different light cure orthodontic adhesives: An in vitro study

To compare the shear bond strength and Adhesive Remnent Index (ARI) of metal brackets using four different bonding systems: Heliosit Orthodontic Bonding Material (Ivoclar Vivadent), Ormco Enlight Light Cure Adhesive, Transbond XT Light Cure Adhesive (3M UNITEK) and Light cured Orthofix (Anabond Stedman Pharma Research (P) Ltd. In the present study 120 extracted sound human upper bicuspids were taken and divided into four groups. Group 1: Heliosit Orthodontic Bonding Material (Ivoclar Vivadent), Group 2 : Ormco Enlight Light Cure Adhesive ,Group 3: Transbond XT Light Cure Adhesive(3M UNITEK) and Group 4: Light cured Orthofix (Anabond Stedman Pharma Research (P) Ltd. In all the groups (n = 120) orthodontic metal brackets were bonded with the four different light cure adhesives respectively and all the samples were evaluated for shear bond strength using Instron(3366) universal testing machine at a cross speed of 1 mm/min. The bracket failure mode was examined using Adhesive Remnant Index (ARI). The Inter group comparison (&amp;#62;2 groups) was done using one way ANOVA followed by pair wise comparison using post hoc test. Comparison of frequencies of categories of variables with groups was done using Chi square test. For all the statistical tests, p&amp;#60;0.05 was considered to be statistically significant, keeping α error at 5% and β error at 20%, thus giving a power to the study as 80%.: It was concluded that the mean shear bond strength of the Transbond XT was highest among the four adhesives studied. However all the adhesives tested exhibits adequate bond strength for clinical use and ARI scores was nearly same for the Transbond and Enlight adhesives studied.

Efficacy of Photobiomodulation Therapy Versus Soft Acrylic Wafer for Reduction of Pain Associated with Orthodontic Metal Bracket Removal: A Clinical Trial.

Objective: This study compared the efficacy of photobiomodulation therapy versus soft acrylic wafer for reduction of pain associated with orthodontic metal bracket removal. Background: It has been demonstrated that different methods of bracket removal are associated with different levels of pain. Photobiomodulation decreases the level of pain due to its biological effects. Methods: This split-mouth randomized clinical trial evaluated 28 orthodontic patients. The four quadrants in each patient were randomly assigned to four groups of diode laser (940 nm, 31.7 J/cm2 energy density, 1.7 cm2 spot size, 300 mW power, continuous-wave, contact mode) irradiated to the buccal and palatal surfaces of each tooth, soft acrylic wafer, laser in off mode (placebo), and no intervention (control). The severity of pain experienced by patients was assessed immediately after bracket removal from each tooth using a visual analog scale. Data were analyzed using the generalized estimating equation (α = 0.05). Results: The mean pain score in the soft acrylic wafer (p = 0.017), control (p < 0.001), and placebo (p < 0.001) groups was significantly higher compared with the laser group. Gender (p = 0.209), age (p = 0.095), and laterality (right/left quadrant; p = 0.383) had no significant effect on the pain score. The pain score in the mandible was significantly lower compared with the maxilla (p = 0.027). The first and second premolars had significantly lower pain scores (p < 0.05). Conclusions: Within the limitations of this study, photobiomodulation therapy and soft acrylic wafer can both decrease the pain associated with metal bracket removal, but laser is more effective.

Comparison of shear bond strength of metal orthodontic brackets bonded to a CAD/CAM prosthetic provisional material after the use of a self-adhesive resin cement versus a light adhesive paste and different surface conditioning protocols: An in vitro study

Adult orthodontic treatment has been increasingly popular, and brackets may need to be bonded to provisional crowns, including CAD/CAM crowns. The use of self-adhesive resin cement or light adhesive paste have been suggested with different surface conditioning protocols to improve the adhesion to CAD/CAM PMMA provisional crowns. Objective To determine and compare the in vitro shear bond strength (SBS) of metal brackets bonded to a provisional prosthetic CAD/CAM material after the use of different adhesive cements and surface conditioning protocols. One hundred twenty Telio® CAD specimens were manufactured in 12 groups (n=10). Each specimen was bonded to a metal bracket and divided according to adhesive technique (3M™Transbond™ XT Light Cure Paste or 3M™RelyX™ U200) surface treatment (macroretentions) and the use of silane. Half of the specimens were thermocycled (5000 cycles, 5°C/55°C water baths). The SBS test was carried out using a shear bond strength tester, and the type of adhesive failure was determined by means of the adhesive remnant index. The data were analysed with the Mann-Whitney test (α=0.05). Statistically significant differences (P<0.001) in SBS were found among the groups. The group with macroretentions, silane, and not thermocycled was the one that obtained the highest average value (17.31±4.89MPa). The lowest average value was the group without macroretentions, without silane, and thermocycled (3.4±3.37MPa). The shear bond strength of brackets to provisional prosthetic CAD/CAM materials depended on the type of adhesive, surface treatment, and aging by thermocycling.

Shear bond strength of metallic orthodontic brackets to zirconium crowns treated by sandblasting compared to enamel using a universal adhesive: An in vitro study

Orthodontic brackets are increasingly bonded to the surface of zirconium crowns due to the growing aesthetic demands in adults' restorations. Therefore, providing a reliable bond between these substrates is of great importance. This study aimed at investigating the shear bond strength (SBS) of orthodontic metal brackets bonded to zirconium treated by sandblasting. In addition, the value was compared with SBS between metal brackets and enamel. Samples were divided into three groups including first premolar enamel specimens (n=20), untreated zirconium blocks (n=20) and sandblasted zirconium blocks (n=20). Enamel specimens underwent etching and bonding procedures using 37% phosphoric acid and 3M™ Scotchbond™ Universal adhesive. Zirconium blocks were randomly allocated to two groups. The first group was prepared by sandblasting with 50μm aluminium oxide particles (Al2O3) under 4 bars pressure followed by bonding brackets with 3M™ Scotchbond™ Universal adhesive. Metal brackets were also bonded to the untreated zirconium group using the same adhesive. All samples underwent thermocycling, and SBS was calculated using a universal testing machine with a crosshead speed of 1mm/min. Data were analysed using One-way Anova and Tukey's tests. The highest SBS was recorded in sandblasted zirconium group (26.17±8.22MPa) followed by enamel group (23.667±7.00MPa) and untreated zirconium group (11.49±7.00MPa). There was a significant difference between the SBS of untreated zirconium and that of two other groups. Perfect SBS was achieved by sandblasting pre-treatment, comparable to that of enamel. Therefore, sandblasting of zirconium crowns is recommended prior to bonding orthodontic brackets.

The Effect of Hydrogen Peroxide and Povidone-Iodine on the Shear Bond Strength of Orthodontic Brackets: An In Vitro Study

BACKGROUND: Chlorhexidine, which is the gold-standard antimicrobial mouthwash, cannot effectively decrease the count of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the causative agent for coronavirus disease-2019 (COVID-19). Since SARS-CoV-2 is susceptible to oxidation, mouthwashes containing oxidizing agents such as hydrogen peroxide (H2O2) or Povidone-iodine (PVP-I) are recommended to decrease the viral count. AIM: This study aimed to assess the effects of H2O2 and PVP-I mouthwashes on the shear bond strength (SBS) of metal orthodontic brackets to the enamel. MATERIALS AND METHODS: This in vitro experimental study evaluated 45 freshly extracted maxillary premolars. The teeth were cleaned and randomized into three groups (n = 15) for rinsing with distilled water (control group), 1% PVP-I (betadine), and 1.5% H2O2 for 60 s. All teeth were etched with 37% phosphoric acid gel, and metal orthodontic brackets were bonded to the teeth using the Transbond XT bonding system. The teeth were mounted in auto-polymerized acrylic resin and incubated in water at 37°C for 72 h. The teeth were then thermocycled for 48 h, and their SBS was measured in a universal testing machine. The adhesive remnant index (ARI) score was also calculated. The groups were compared by ANOVA and Chi-square Monte Carlo test. RESULTS: No significant difference was noted among the three groups in SBS (p = 0.938) or the ARI score (p = 0.780). CONCLUSION: Use of H2O2 and PVP-I mouthwashes has no adverse effect on SBS or mode of failure of metal orthodontic brackets bonded to enamel.

Contrary to an old belief, four corner curing does not provide more bond strength or polymerization in bonding of orthodontic metal brackets

Objectives: The study aimed to investigate the effect of the direction of light curing on bond strength and adhesive polymerization of orthodontic metal brackets. Material and Methods: In this in vitro investigation, 75 extracted human upper premolars were randomly divided into three groups according to the curing direction: Group A (20 s curing from the occlusal side of the bracket), Group B (10 s from occlusal and 10 s from gingival), and Group C (5 s from four corners of the bracket). After bonding, the brackets were subjected to a shear bond strength (SBS) test performed with a universal testing machine. Moreover, Fourier transform infrared spectroscopy (FTIR) analysis was used to find the polymerization ratio of the adhesives in each group. Kruskal–Wallis test was to statistical analysis of SBS and FTIR data, respectively, at the 0.05 level of significance. Results: The difference in SBS of metal brackets was not statistically significant between the groups (P &gt; 0.05). However, the difference in polymerization ratio was significant between all groups where the highest and lowest ratio belonged to Groups A and B, respectively (P &lt; 0.05). Conclusion: Curing metal brackets from four corners do not increase their bond strength and/or polymerization.

Effects of Er, Cr: YSGG Laser on Shear Bond Strength of the Orthodontic Brackets for 5 and 10 Seconds: An In Vitro Study.

Objectives The study designed to compare the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser at different power outputs and short periods of time (5 and 10 s) and acid etching on the shear bond strength (SBS) and failure mode of metallic orthodontic brackets. Material and methods. A total of sixty-nine human premolars extracted for orthodontic purposes were used. 60 teeth were randomly assigned to one of the five treatment groups. (n = 12): group 1: 37% phosphoric acid etching and groups 2–5: the enamel surface irradiated by the Er, Cr: YSGG laser operated at different power outputs (1 W, 1.5 W, 2 W, and 2.5 W), each laser group was divided into two subgroups (n = 6) according to exposure time (5 s and 10 s). Nine teeth were not subjected to SBS testing but were prepared for scanning electron microscopy (SEM). The nonparametric Kruskal–Wallis test was used to evaluate the data; the SBS and adhesive remanent index (ADI) were evaluated. Results The mean SBS for all laser groups and the acid-etched group were comparable, with no significant differences except for the 1 W group for 5 and 10 s and the 1.5 W group for 5 s. For the ARI scores, no statistically significant difference was found among the groups (P=0.059), and the majority of the samples had ARI type 2 or 3. Conclusion The laser irradiation at 2 and 2.5 W for 5 s was similar to that produced by acid etching, whereas the laser irradiation at 2 and 2.5 W at 10 s was higher compared with that obtained with acid etching and adequate to etch the enamel.

Effects of Three Novel Bracket Luting Agents Containing Zirconia Primer on Shear Bond Strength of Metal Orthodontic Brackets Attached to Monolithic Zirconia Crowns: A Preliminary In Vitro Study.

Background The increased use of zirconia crowns in adult orthodontic patients warrants the establishment of methods and materials to adhere orthodontic brackets properly to zirconia crowns. However, studies in this regard are scarce, and many materials remain untested. This preliminary study aimed to examine three new adhesives containing zirconia primers for the first time. Methods Sixty identical monolithic zirconia crowns were fabricated and randomly divided into 4 groups of 15 each (Panavia SA Cement Plus, G-CEM, TheraCem, and Transbond XT Composite (control)). After glaze removal with a diamond bur, a metal orthodontic bracket was attached to the surfaces of the crowns using the respective adhesive. Specimens were incubated at 37°C and then thermocycled for 2000 cycles. Shear bond strengths (SBS) of brackets in different groups were estimated using a universal testing machine. Mean SBS values were compared with the values 6, 8, and 10 (as acceptable SBS values) and 13 MPa (as the maximum SBS tolerable by zirconia) using the one-sample t-test. They were also compared with each other using the one-way ANOVA and Tamhane post hoc test (α = 0.05). Results The ANOVA indicated a significant overall difference; the Tamhane test showed that the difference between the control group and all test groups was significant (P < 0.0005); however, the 3 test groups were not significantly different from each other (P > 0.30). The SBS of the control group was significantly lower than the minimum acceptable SBS (6 MPa, P < 0.0005). The mean SBS of the TheraCem was not significantly different from 10 MPa (P = 0.902), while the mean SBS values of Panavia SA Cement Plus and G-CEM were significantly greater than 10 MPa (P < 0.05). None of the three zirconia adhesives had mean SBS values higher than 13 MPa. Conclusion All novel zirconia adhesives (Panavia SA Cement Plus, G-CEM, and TheraCem) generated SBS values adequate to attach metal orthodontic brackets to zirconia prostheses (at or greater than 10 MPa) without damaging the zirconia during bracket removal (not above 13 MPa).

Efficacy of products for bleaching and whitening under orthodontic brackets.

Many patients wearing orthodontic appliances request alterations in the shade of their teeth during orthodontic treatment. This study aimed to evaluate the efficacy of different products for bleaching and whitening under orthodontic brackets. Seventy bovine incisors were randomly divided into five groups (n = 14): C) non-whitening toothpaste (control); WTsi) hydrated silica whitening toothpaste; WThp) 2% hydrogen peroxide whitening toothpaste; OB) in-office bleaching; and HB) at-home bleaching. Two buccal surface areas were evaluated using the Easyshade spectrophotometer: under the metal bracket (experimental) and around the bracket (control). The paired t-test, ANOVA, and Tukey tests were applied for statistical analysis. Intragroup comparisons showed that in groups C, WThp and HB, there were statistically significant differences in the enamel color changes (ΔEab) between under and around the bracket areas (C - under bracket = 7.97 ± 2.35, around bracket = 2.86 ± 0.81, p< 0.01; WThp - under bracket = 4.69 ± 2.98, around bracket = 2.05 ± 1.41, p< 0.01; HB - under bracket = 7.41 ± 2.89, around bracket: 9.86 ± 3.32, p= 0.02). Groups WTsi, OB and HB presented similar perception of tooth whiteness (ΔWID) between the tested areas. Intergroup comparisons demonstrated that under the bracket area, the color change (ΔEab) was similar for all groups, except WThp (C = 7.97 ± 2.35; WTsi = 8.54 ± 3.63; WThp = 4.69 ± 2.98; OB = 9.31 ± 4.32; HB = 7.41 ± 2.89; p< 0.01). The dental color changes were effective for the products tested in groups WTsi, OB and HB in the presence of metallic orthodontic brackets.

Residual Adhesive Removal Methods for Rebonding of Debonded Orthodontic Metal Brackets: Systematic Review and Meta-Analysis.

Debonding of orthodontic brackets is a common occurrence during orthodontic treatment. Therefore, the best option for treating debonded brackets should be indicated. This study aimed to evaluate the bond strength of rebonded brackets after different residual adhesive removal methods. This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, Web of Science, The Cochrane Library, SciELO, Scopus, LILACS, IBECS, and BVS databases were screened up to December 2020. Bond strength comparisons were made considering the method used for removing the residual adhesive on the bracket base. A total of 12 studies were included for the meta-analysis. Four different adhesive removal methods were identified: sandblasting, laser, mechanical grinding, and direct flame. When compared with new orthodontic metallic brackets, bond strength of debonded brackets after air abrasion (p = 0.006), mechanical grinding (p = 0.007), and direct flame (p < 0.001) was significantly lower. The use of an erbium-doped yttrium aluminum garnet (Er:YAG) laser showed similar shear bond strength (SBS) values when compared with those of new orthodontic brackets (p = 0.71). The Er:YAG laser could be considered an optimal method for promoting the bond of debonded orthodontic brackets. Direct flame, mechanical grinding, or sandblasting are also suitable, obtaining clinically acceptable bond strength values.

Bond assessment of enamel conditioned with Er, Cr: YSGG laser and methylene blue photosensitizer activated by photodynamic therapy to orthodontic metallic brackets

AimTo assess bond integrity and failure mode after enamel pretreated with conventional and contemporary conditioning methods were bonded to metallic brackets (MB). Material and methodsForty maxillary central incisors were selected and disinfected. All specimens were mounted up to the cement-o-enamel junction and divided into four experimental groups randomly based on the enamel conditioning technique. Photodynamic therapy (PDT) was used to condition enamel in group 1, Total-etch and rinse (TER) was used to treat samples in group 2, Specimens in group 3 were conditioned with ECL, and samples in group 4 surface pretreated with SEP. Bonding of MB was performed on the surfaces of all the specimens with a Transbond XT. Specimens from all investigated groups were positioned on a universal testing machine maintaining buccal surfaces similar to the direction of the force. After bracket debonding bond failure was assessed using ARI. The bond integrity of all four groups was compared using analysis of variance (ANOVA). Post hoc Tukey test was used for pairwise comparison among different groups. ResultsGroup 2, TER+MB (15.38±0.14 MPa) displayed the highest bond value whereas the lowest values of SBS were exhibited by group 1, PDT+MB (10.11±0.17 MPa). The inter-group comparison revealed that specimens of group 2 and group 3, ECL+MB (14.61±0.55 MPa) demonstrated comparable bond strength (p>0.05). ConclusionEnamel conditioned with TER and ECL demonstrated comparable SBS. However, bond integrity after PDT and SEP (self-etch primer) surface treatment of enamel bonded with MB significantly lowered bond values.

Proteome difference among the salivary proteins adsorbed onto metallic orthodontic brackets and hydroxyapatite discs.

The aim of this study was to investigate the atomic composition and the proteome of the salivary proteins adsorbed on the surface of orthodontic metallic bracket. For this, the atomic composition of orthodontic metallic brackets was analyzed with X-ray Photoelectron Spectroscopy (XPS). The acquired bracket pellicle was characterized after brackets were immersed in human whole saliva supernatant for 2 hours at 37°C. Hydroxyapatite (HA) discs were used as a control. Acquired pellicle was harvested from the HA discs (n = 12) and from the metallic brackets (n = 12). Proteomics based on mass spectrometry technology was used for salivary protein identification and characterization. Results showed that most of the proteins adsorbed on the surface of orthodontic metallic brackets and on the HA discs were identified specifically to each group, indicating a small overlapping between the salivary proteins on each study group. A total of 311 proteins present on the HA discs were unique to this group while 253 proteins were unique to metallic brackets, and only 45 proteins were common to the two groups. Even though most proteins were unique to each study group, proteins related to antimicrobial activity, lubrication, and remineralization were present in both groups. These findings demonstrate that the salivary proteins adsorbed on the bracket surface are dependent on the material molecular composition.

Bond Strength of Orthodontic Brackets to Temporary Crowns: In Vitro Effects of Surface Treatment.

Background The number of patients seeking orthodontic treatment has been consistently increasing. During orthodontic treatment, it is recommended to place the provisional restoration and to delay the final restoration until completion of orthodontic treatment. Recurrent bracket debonding necessitates orthodontists to prepare the bonding area with special measures. Objective This study aimed to evaluate the effect of different grit sizes of diamond burs and sandblasting surface treatment on the shear bond strength of orthodontic brackets to provisional crowns. Materials and Methods A total of 75 discs were fabricated from a bisacrylic composite and divided into 5 groups (n = 15) according to surface treatment by black, blue, and green diamond burs and sandblasting in addition to a control group. Metal orthodontic brackets were bonded to discs in a standardized conventional manner. All specimens were subjected to thermocycling with 5000 cycles of alternating 5°C and 55°C waterbaths. The shear bond strength test was performed using a universal testing machine. A scanning electron microscope (SEM) was used to analyze the surface treatment effect and features of debonded surfaces. The amount of composite resin left on the specimen surfaces was analyzed and classified with the adhesive remnant index. One-way ANOVA was performed at α = 0.05. Results The shear bond strength of specimens treated with sandblasting was significantly higher than that of the control group under thermal aging conditions (p=0.022), as well as blue burs (p=0.001), while no significant differences were found between different grit diamond burs and the controls (p > 0.05). Conclusion Under thermocycling conditions, sandblasting of provisional crowns increases the bond strength of orthodontic brackets.