Orthodontic Bonding: Review of the Literature

Effectiveness of Different Etching Agents on Enamel Surface and Shear Bond Strength: An In Vitro Evaluation

Background Enamel etching is of utmost importance during the orthodontic bonding procedure. Phosphoric acid, hydrofluoric acid, and citric acid are used in specific concentrations to create surface irregularities on enamel surfaces, enhancing the bond strength of the orthodontic attachment. Therefore, it is essential to evaluate the type of etchant for reliable orthodontic bracket bonding with minimal damage to the enamel surface. Aims and objectives This study aimed to investigate the morphological changes on the enamel surface after treatment with different surface etchants, assess the depth of penetration, and evaluate the shear bond strength (SBS) of orthodontic brackets. Materials and methods One hundred and one extracted premolar teeth were used to investigate morphological changes on the enamel surface treated with 37% phosphoric acid, 11% hydrofluoric acid, and 20% citric acid. It was evaluated on a scanning electron microscope (Jeol Scientific Equipment, Jeol Limited, Akishima, Japan), and the SBS of brackets on enamel treated with different etching agents was evaluated using an Instron Universal Testing Machine (UTM; Instron Model: 5982, Universal Testing Systems, Norwood, MA). Group A had 60 test samples. Group B had 40 test samples. One control without any acid etching was used in both groups. Subgroup A1 (n = 30) was evaluated for surface characteristics of acid-etched enamel. Subgroup A2 was assessed for the penetration depth of various etchants. Group B (n = 40) was tested for SBS. The results were tabulated and analyzed using IBM SPSS Statistics, version 20.0 (IBM Corp., Armonk, NY). Post hoc Tukey HSD test and one-way analysis of variance were used to assess SBS and penetration depth of etchants (P ≤ 0.05). Pearson's correlation test was used to correlate SBS, etching pattern, and penetration depth. The chi-square test was used to test the frequency of types of etching patterns.  Results Intergroup correlations between etching depth, etching pattern evaluated on SEM, and SBS evaluated on the UTM showed a high statistical correlation between etching depth & SBS, etching depth & etching pattern, and SBS & etching pattern between A1, A2, and group B (P ≤ 0.001). A highly significant negative correlation between SBS & etching pattern (P = 0.42) was observed among intra-group correlation. Non-significant correlations were found between etching depth & SBS and etching depth & etching pattern within the 20% citric acid etch group (P = 0.370 and 0.141, respectively). Conclusion Penetration depth obtained was highest with 11% hydrofluoric acid, followed by 37% phosphoric acid and 20% citric acid. In addition, 11% hydrofluoric acid showed the highest bond strength. Acid etching showed better penetration depth and bond strength than control.

Shear bond strength of a RMGIC for orthodontic bracket bonding to enamel

OBJECTIVE

To evaluate the shear bond strength (SBS) of a restorative resin-modified glass ionomer cement (RMGIC) for orthodontic bracket bonding.

MATERIALS AND METHODS

One hundred twenty-one human teeth were randomly divided into 11 groups (n = 11) according to the surface treatment applied (H3PO4 ± Transbond Plus (TSEP) or Scotchbond Universal (SU)), and the adhesive used (Riva LC HV (RIVA), Fuji Ortho (FUJI), and Transbond XT (TXT)). For each sample, a metal button was bonded. SBS tests were performed at 1 week and debonded specimens were observed for failure modes determination. One-way ANOVA followed by Tukey's post hoc test was used to compare SBS differences and Fisher's exact test to analyze the failure modes (p < 0.05).

RESULTS

TSEP + FUJI and H3PO4 + SU + TXT showed the highest SBS values while H3PO4 + TSEP + RIVA showed the lowest value. Cohesive failure and mixed failure were found in the groups with SU and TXT and adhesive failure in the other groups.

DISCUSSION/CONCLUSIONS

The bonding of orthodontic attachments to enamel could be performed with any of the three materials studied. The use of a universal adhesive in the bonding protocol could optimize the adhesion values. Clinical studies would be needed to confirm the results obtained.

The Effect of Various Lasers on the Bond Strength Between Orthodontic Brackets and Dental Ceramics: A Systematic Review and Meta-Analysis

Background/objective: This systematic review and meta-analysis aimed to assess how laser conditioning affected brackets bonded to dental ceramics' shear bond strength (SBS). Materials and methods: The study was conducted by searching Pubmed/Medline, Scopus, Embase, Web of Science, the Cochrane Library, and Google Scholar up to September 14, 2022. In addition, the reference lists of the relevant articles were checked manually. Articles that compared SBS of laser-treated feldspathic, lithium disilicate, or zirconia surfaces with other standard techniques for bonding metal or ceramic orthodontic brackets were considered. Using a random-effects model, data pooling was carried out as the weighted mean difference (WMD). Results: This study initially contained 1717 reports, and following review, 32 articles were deemed suitable for our meta-analysis. The pooling results showed that the treatments with lasers such as "Er:YAG" [WMD = -1.12 MPa; 95% confidence interval (CI): -1.93 to -0.31], "Er:YAG + Silane" (WMD = -3.08 MPa; 95% CI: -4.77 to -1.40), and "Nd: YAG + Silane" (WMD = -2.58 MPa; 95% CI: -3.76 to -1.40) had statistically significant lower adhesion values compared with controls. Contrarily, "Ti:Sapphire femtosecond" demonstrated significantly higher bonding values (WMD = 0.94 MPa; 95% CI: 0.29-1.60). In contrast, other interventions obtained no statistically significant difference in SBS. Conclusions: Most of the laser groups showed results comparable with those of conventional approaches. Although more research is necessary for definitive conclusions, laser treatment may be an effective option for treating the surfaces of ceramic materials.

Has the COVID-19 Pandemic Affected Orthodontists' Interest in Various Orthodontic Appliances?

Objective

To determine the changes in orthodontists' interest in various orthodontic appliances during the coronavirus disease-2019 (COVID-19) pandemic.

Methods

A questionnaire probing respondents' interest in orthodontic appliances and techniques, including standard buccal metal brackets, self-ligating brackets, standard ceramic brackets, lingual brackets, clear aligners, orthodontic facemasks, removable functional appliances, fixed functional appliances, orthognathic surgery, orthodontic miniscrews, and lingual retainers, was prepared using Google Forms and then sent to the Turkish Orthodontic Society to invite all members of the society to participate in the survey. Of the 1903 members invited, 230 (response rate, 12.08%) orthodontists completed the questionnaire.

Results

The respondents' interest in brackets did not change among 70% of the respondents (standard buccal metal bracket 80%, self-ligating bracket 72.2%, standard ceramic bracket 77%, and lingual bracket 76.5%). A significant difference was observed between the genders only about the interest in standard metal brackets and fixed functional appliances (p<0.05 for both). Interest in standard metal brackets decreased as respondents' work experience increased (p<0.05). The interest in self-ligating brackets was higher among respondents with 1-5 years of experience than among other respondents (p<0.05). Interest in self-ligating brackets increased more among lecturers and residents than among clinicians (p<0.05).

Conclusion

The interest of orthodontists in clear aligners showed the highest increase during the COVID-19 pandemic among all orthodontic appliances, whereas their interest in other appliances, particularly standard buccal metal brackets, did not change.

Effects of Plasma Treatment on the Strength of Bonding to Ceramic Surfaces in Orthodontics-A Comprehensive Review

Over the past several decades, orthodontic treatment has been increasingly sought out by adults, many of whom have undergone restorative dental procedures that cover enamel. Because the characteristics of restorative materials differ from those of enamel, typical bonding techniques do not yield excellent restoration-bracket bonding strengths. Plasma treatment is an emerging surface treatment that could potentially improve bonding properties. The purpose of this paper is to evaluate currently available studies assessing the effect of plasma treatment on the shear bond strength (SBS) and failure mode of resin cement/composite on the surface of ceramic materials. PubMed and Google Scholar databases were searched for relevant studies, which were categorized by restorative material and plasma treatment types that were evaluated. It was determined that cold atmospheric plasma (CAP) treatment using helium and H2O gas was effective at raising the SBS of feldspathic porcelain to a bonding agent, while CAP treatment using helium gas might also be a potential treatment method for zirconia and other types of ceramics. More importantly, CAP treatment using helium has the potential for being carried out chairside due to its non-toxicity, low temperature, and short treatment time. However, because all the studies were conducted in vitro and not tested in an orthodontic setting, further research must be conducted to ascertain the effectiveness of specific plasma treatments in comparison to current orthodontic bonding treatments in vivo.

Shear Bond Strength of Metal and Ceramic Brackets Depending on Etching Protocol in Direct Bonding Technique

Successful orthodontic therapy, apart from a proper treatment plan, depends on optimal bracket-enamel adhesion. Among numerous factors affecting adhesion, the type of bracket and preparation of the tooth's surface are crucial. The aim of this study was to compare the shear bond strength (SBS) of metal and ceramic brackets to the enamel's surface using direct bonding. Forty extracted human premolars were divided into four groups according to the etching method (etch-and-rinse and self-etch) and bracket type. The SBS and adhesive remnant index (ARI) were determined. The ceramic brackets achieved the highest SBS values both in the self-etch (SE) and etch-and-rinse (ER) protocols. Higher SBS values for ceramic and metallic brackets were found in the ER protocol. In all tested groups, the achieved SBS value was satisfactory to withstand orthodontic and occlusal forces. There was no significant difference in the ARI score between study groups (p = 0.71). The fracture occurred between the bracket base and adhesive material in both types of brackets, which decreased the risk of enamel damage during debonding.

Influence of surface treatments on the bond strength of metal brackets to CAD/CAM materials and discoloration after various refinishing procedures : Scanning electron microscopy and atomic force microscopy study

PURPOSE

This study evaluated the shear bond strength (SBS) of a metal bracket bonded to three different computer-aided design/computer-aided manufacturing (CAD/CAM) restoration materials pretreated with different surface treatments. In addition, the surface topography and color change of the restorations after debonding with two different tungsten carbide burs were examined.

METHODS

A total of 216 plates were cut from three different CAD/CAM blocks, each of which was divided into three subgroups with different pretreatment methods: (1) acid etching, (2) sandblasting, and (3) laser irradiation. Incisor metal brackets were bonded. The SBS test was performed, and the failure types were classified. Then, samples were randomly divided into two subgroups according to the adhesive removal procedure to be used: a tungsten carbide bur with 12 blades or 24 blades (n = 12). Color change was calculated based on the ∆E00, and surface morphology was evaluated via SEM and AFM analysis.

RESULTS

The SBS data revealed that the type of CAD/CAM material and the applied surface treatment significantly affected bond strength. The highest SBS values were detected for the Grandio Blocs (VOCO GmbH, Cuxhaven, Germany; 14.3 ± 4.4 MPa), and the lowest was observed for Cerasmart (GC Europe, Leuven, Belgium; 12.0 ± 4.0 MPa). The ∆E00 results demonstrated significant differences only as a result of the applied surface treatment. The ∆E00 value in all groups was above the 1.77 threshold.

CONCLUSION

CAD/CAM material types and surface treatments affected the bond strength, but the interactions of these factors did not. The chosen surface treatment also significantly affected the ∆E00 after the polishing was done.

Comparative Assessment of Bracket Bond Failure Rates of a Novel Chitosan-Based Orthodontic Primer: An In Vivo Split-Mouth Study

Introduction An unavoidable side effect of orthodontic fixed appliance therapy is the demineralization of the enamel surface surrounding the bracket at the adhesive and tooth interface due to a microgap formation, which serves as a nidus for biofilm growth. Due to this, it is advantageous to include antibacterial agents in orthodontic primers without affecting their clinical properties. The aim of this study was to compare the in vivo bracket bond failure rates of a novel chitosan-based primer with a conventional orthodontic primer. Materials and methods Fifty-four subjects and 1,080 brackets were included in this study. At the end of six months, 45 subjects and 960 brackets bonded using novel chitosan-based primers and conventional primers (Anabond, Anabond Stedman Pharma Research Pvt Ltd, Chennai, India). Each was evaluated for a bracketed bond failure rate. Descriptive statistics and Chi-square tests were used for statistical analysis. Results The results revealed that the bracket bond failure rate in Group 1 (novel chitosan-based primer) was 27 brackets (3%) and 23 brackets in Group 2 (conventional primer) (2.5%), with no statistically significant difference between the two groups (p>0.05). There was a statistically significant difference in the bracket failure rate between the maxillary arch (2%) and the mandibular arch (3.5%) (p<0.05). Conclusion Brackets bonded with the chitosan-modified novel orthodontic primer showed no statistically significant difference in bracket bond failure rate when compared to the conventional primer. Bond failure rates were higher in the mandibular teeth when compared to the maxillary teeth.

Shear Bond Strength between Orthodontic Brackets and Monolithic 4Y-TZP: An In Vitro Study

The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) between metal orthodontic brackets and monolithic zirconia surfaces bonded with resin composite. Fifty monolithic zirconia (4Y-TZP) disks were sintered and glazed. Specimens were divided into five groups (n = 10) for different surface treatments: control, nano second fiber laser, sandblasting, grinding and tribochemical coating (CoJet Sand 30-μm). Metal orthodontic brackets were bonded to monolithic zirconia surface by two-component orthodontic adhesive. After 500 cycles of thermocycling, shear bond strength values were measured by a universal testing machine at a cross head speed of 0.5 mm/min. The data was recorded as MPa and statistically analyzed with One-way ANOVA, Levene's LSD tests with Bonferroni corrections. The significance level was α = 0.05. The surface topography of one specimen of each group was evaluated by scanning electron microscopy (SEM). Statistically significant difference was observed among study groups (p = 0.018). The lowest shear bond strength was observed in the control group (3.92 ± 1.9). Tribochemical coating showed the highest bond strength (7.44 ± 2.9), which was statistically different from the control and nano second laser (4.3 ± 1.4) groups but not statistically different from grinding (6.15 ± 3.1) or sandblasting (6.47 ± 3.3). SEM images showed comprehensive results of each surface treatment on monolithic zirconia. All failure modes were recorded as adhesive between the composite resin and monolithic zirconia. Based on the findings of this study, it can be concluded that grinding, sandblasting and tribochemical coating techniques showed clinically acceptable bond strength within the range of 6-8 MPa. These surface treatments can be considered suitable for achieving a durable bond between metal orthodontic brackets and monolithic 4Y-TZP ceramic surfaces.

Shear bond strength of adhesive precoated brackets: A comparative in vitro study

OBJECTIVE

This study compared the shear bond strength of orthodontic precoated brackets from different manufacturers.

METHODS

Sixty extracted human premolar teeth were divided into six groups (n=10). The groups were bonded with one of the following brackets: 3M™ Unitek Victory™ Series™ with APC, 3M™ Unitek Clarity™ Advanced Ceramic™ with APC, TP Nu-Edge® NX Cobalt-Chromium and TP In-Vu® ceramic Readi-Base® both with eXact® orthodontic adhesive, 3M™ Unitek Clarity Advanced Ceramic™ and 3M™ Unitek Victory™ Series™ both with Transbond™ XT Adhesive. Each group was tested for shear bond strength using a universal testing machine. Each sample was observed under a dissecting microscope and received an adhesive remnant index (ARI) score. Statistical analysis was performed using Tukey's Standardized Range (HSD) Test to make comparisons among all groups and a Wilcoxon rank-sum test to evaluate for pairwise comparisons between the groups. The P-values<0.05 were considered significant.

RESULTS

The ceramic control was not statistically different from the metal control, 3M™ Victory™ APC™, TP In-Vu® ceramic eXact® or TP Nu-EDGE® eXact® in terms of shear bond strength (7.69±1.41MPa, 7.72±1.25MPa, 8.70±1.93MPa, 4.90±1.76MPa, 5.33±0.78MPa, respectively). However, it was statistically different from 3M™ Ceramic APC™ (10.29±2.78MPa). In terms of modulus, there were no statistical differences. TP's Nu-edge® had the lowest average ARI score, but was not statistically different when compared to the other groups.

CONCLUSION

3M™ Unitek's Ceramic APC had a statistically higher SBS than the non-precoated brackets and TP Orthodontics' precoated brackets. However, all SBS were 4.9 MPA or above, which is deemed clinically acceptable in terms of laboratory forces. There was no statistical difference between manufacturing companies or precoated vs. non-precoated modulus and ARI scores.

In Vitro evaluation of the bond strength of metal brackets adhered to different dental restorative materials using different orthodontic adhesives

Background

During orthodontic treatment, teeth with brackets may sometimes be restored with different restorative materials. In this case, the content of the orthodontic adhesive selected for bracket bonding may also be important.

Aim

This study compared the bond strength of metal orthodontic brackets adhered to different resin composite and glass ionomer cement (GIC) restoration surfaces with glass ionomer-based and resin-based orthodontic adhesives to determine the best orthodontic adhesive for use in restored teeth.

Material and Methods

This study prepared 80 discs. Four material groups of 20 discs were created: reinforced high-viscosity GIC, high-viscosity GIC, flowable bulk-fill resin composite, and nanohybrid resin composite. Specimens in each material group were divided into two subgroups that differed in the orthodontic adhesive used to bond the brackets to the prepared specimens. After 24 hours, the specimens were shear bond strength (SBS) tested at 1 mm/min using a universal tester.

Results

The SBS of glass ionomer-based orthodontic adhesive differed significantly between metal brackets adhered to different bases (P < 0.001). The highest SBSs were observed between metal brackets and high-viscosity glass ionomer restorations (6.79 ± 2.38). The highest SBSs observed with a resin-based orthodontic adhesive were between metal brackets adhered to nanohybrid resin composite restorations (8.84 ± 2.10; P = 0.030).

Conclusions

Glass ionomer-based orthodontic adhesive provided safer bond strength and demineralization prevention when applying metal brackets to teeth with glass ionomer restorations.

Effect of Different Types of Adhesive Agents on Orthodontic Bracket Shear Bond Strength: A Cyclic Loading Study

Bracket failure is one of the most important problems encountered during fixed orthodontic treatment. For this reason, different types of adhesive agents have been developed over the years. Consequently, the aim of this study was to evaluate the shear bond strength of brackets bonded to teeth etched with a conventional acid etching method in a laboratory environment by using different types of adhesive agents and comparing the number of shear strokes. Sixty human maxillary premolars were divided into three groups and Gemini stainless steel metal brackets (3M Unitek, Monrovia, CA, USA) were bonded to all teeth. In Group 1, Transbond™ XT Primer (3M Unitek, Monrovia, CA, USA) and Transbond™ XT Light Cure Adhesive Paste composite (3M Unitek, Monrovia, CA, USA) were used. In Group 2, BracePaste® MTP Primer (American Orthodontics, Sheboygan, CA, USA) and BracePaste® Adhesive composite (American Orthodontics, Sheboygan, WI, USA) were used. In Group 3, Ortho Solo™ Primer (Ormco, Orange, CA, USA) and Grengloo™ Adhesive composite (Ormco, Brea, CA, USA) were used. The samples were subjected to a shear test with a closed-loop controlled, low-cycle fatigue machine with a capacity of 10 N and a crosshead speed of 300 mm/min. The number of shear strokes of the brackets was recorded. According to the Kruskal−Wallis and Mann−Whitney U tests performed on the data obtained, statistically significant differences were found between the groups in terms of the numbers of shear strokes (p < 0.05). Significantly higher numbers of shear strokes and higher shear bond strengths were observed in Group 3 compared with Group 1 and Group 2 (p < 0.05). There was no statistically significant difference between the numbers of shear strokes for Group 1 and Group 2 samples (p > 0.05). To conclude the study, it was observed that the type of adhesive used had an effect on the bond strength of the bracket and that the Grengloo™ adhesive agent showed higher shear bond strength. It was observed that BracePaste® Adhesive and Transbond™ XT Light Cure Adhesive Paste adhesive agents had similar shear bond strengths.

Comparison of Bond Strength of Orthodontic Brackets Onto the Tooth Enamel of 120 Freshly Extracted Adult Bovine Medial Lower Incisors Using 4 Adhesives: A Resin-Modified Glass Ionomer Adhesive, a Composite Adhesive, a Liquid Composite Adhesive, and a One-Step Light-Cured Adhesive

BACKGROUND This study aimed to compare the bond strength of orthodontic brackets onto the tooth enamel of 120 freshly extracted adult bovine medial lower incisors using 4 adhesives: a resin-modified glass ionomer adhesive, a composite adhesive, a liquid composite adhesive, and a one-step light-cured adhesive. MATERIAL AND METHODS The study group (120 freshly extracted bovine medial lower incisors) was divided into equal subgroups depending on the type of adhesive used to fix the brackets to the tooth enamel (n=30), and then according to the observation time (n=10). Orthodontic brackets were fixed onto the tooth enamel for 24 hours (T1), 3 months (T2), and 6 months (T3) using 4 types of adhesives: resin-modified glass ionomer adhesive Fuji Ortho LC, composite adhesive Transbond Plus Light Cure Band, flowable composite adhesive Transbond Supreme Low Viscosity, and a one-step light-cured adhesive GC Ortho Connect. Shear tests and fracture plane analyses were performed. RESULTS Statistically significant differences at time T1 were noted in the comparison of shear stress values when brackets were fixed with GC Ortho Connect adhesive compared to other adhesives (P<0.05), except for the Transbond Plus adhesive (P>0.05). At time T3, significant statistical differences occurred between GC Fuji Ortho LC and the other 3 adhesives (P<0.05). The fracture analysis showed that, regardless of the time function, adhesive-cohesive fractures without damage to the enamel were the most common for all the assessed materials. CONCLUSIONS Of the adhesives evaluated, GC Ortho Connect appears to be the most appropriate choice for bonding orthodontic brackets to the enamel surface.

Mechanical characterization of aesthetic orthodontic brackets by the dynamic indentation method

The objective of this study is to investigate the mechanical properties, such as the dynamic hardness and indentation elastic modulus, of commercially available aesthetic orthodontic brackets, such as ceramic and plastic brackets, by the dynamic micro-indentation method. Five ceramic brackets, which were made of alumina (both monocrystalline and polycrystalline forms) or zirconia, and two plastic brackets, which were made of glass fiber-reinforced polycarbonate or polyamide, were tested. There were significant differences in the mechanical properties of the monocrystalline and polycrystalline alumina brackets. The mechanical properties of the glass fiber-reinforced plastic bracket were significantly superior to these of the non-glass-fiber-reinforced plastic bracket. The differences in the crystal structures of the ceramic brackets surface affected the dynamic hardness and indentation elastic modulus. Furthermore, the short glass fibers contained in the plastic bracket might contribute to the improvement of the mechanical properties.

Physico-mechanical properties, antimicrobial activities, and anti-biofilm potencies of orthodontic adhesive containing cerium oxide nanoparticles against Streptococcus mutans

Introduction: White spot lesions around orthodontic brackets may lead to the formation of dental caries during and following fixed orthodontic treatment.

Aim: This study aimed to evaluate the physico-mechanical properties and antimicrobial potencies of orthodontic adhesive doped with cerium oxide nanoparticles (CeO2-NPs) against Streptococcus mutans.

Materials and methods: After synthesis and conformation of CeO2-NPs by transmission electron microscope (TEM), shear bond strength (SBS) and adhesive remnant index (ARI) of modified orthodontic adhesive containing different concentrations of CeO2-NPs (0, 1, 2, 5, and 10 wt%) were measured. The antimicrobial effects of modified orthodontic adhesive were evaluated by disk agar diffusion method and biofilm formation inhibition assay.

Results: The pseudo-spherical shapes of CeO2-NPs were observed in TEM micrographs. The physico-mechanical finding showed that 5 wt% CeO2-NPs showed the highest concentration of CeO2-NPs and SBS value (18.21±9.06 MPa, p&lt;0.05) simultaneously with no significant differences in ARI compared with the control group (p&gt;0.05). There was a significant reduction in cell viability of S. mutans with increasing CeO2-NPs concentration. The 3.1 Log10 and 4.6 Log10 reductions were observed in the count of treated S. mutans with 5 and 10 wt% CeO2-NPs, respectively (p&lt;0.05).

Conclusions: Overall, an orthodontic adhesive containing 5 wt% CeO2-NPs had antimicrobial properties against S. mutans without adverse effects on SBS and ARI.

Effect of Enamel Pretreatment with Pastes Presenting Different Relative Dentin Abrasivity (RDA) Values on Orthodontic Bracket Bonding Efficacy of Microfilled Composite Resin: In Vitro Investigation and Randomized Clinical Trial

Bonding failure is a clinical issue frequently encountered in orthodontic practice. The aim of this study was to evaluate enamel pretreatment both in vitro and clinically using agents with different RDA values before brackets’ bonding, to assess if RDA can affect the Shear Bond Strength (SBS), Adhesive Remnant Index (ARI) and clinical failure rate of orthodontic brackets. For the in vitro study, 220 bovine teeth were pretreated with agents with different RDA values. Subsequently, brackets were bonded. For the clinical study, 20 patients underwent bonding of 20 brackets each with a split-mouth design. Low and high RDA toothpastes were used for enamel pretreatment. SBS, ARI and failures were recorded. Higher SBS values were found for teeth pretreated with lower RDA agents; conversely, lower SBS values were found for teeth pretreated with higher RDA agents (p < 0.05). For high ARI values, RDA increased too (p > 0.05). In the clinical study, a significantly lower failure rate was reported for teeth pretreated with low RDA toothpaste (2.5% in low RDA group, 7.0% in high RDA group; p < 0.05). No significant differences were assessed comparing the two dental arches and anterior and posterior sites. Enamel pretreatment with low RDA toothpastes could increase brackets’ survival rate. Further in vitro and clinical studies would be welcomed to confirm these findings.

What Is the Most Effective Technique for Bonding Brackets on Ceramic-A Systematic Review and Meta-Analysis

Background: There has been an increase in demand for orthodontic treatment within the adult population, who likely receive restorative treatments using ceramic structures. The current state of the art regarding the most effective method to achieve an appropriate bond strength of brackets on ceramic surfaces isn’t consensual. This systematic review aims to compare the available surface treatments to ceramics and determine the one that allows to obtain the best bond strength. Methods: This systematic review followed the PRISMA guidelines and the PICO methodology was used, with the question “What is the most effective technique for bonding brackets on ceramic crowns or veneers?”. The research was carried out in PubMed, Web of Science, Embase and Cochrane Library databases. In vitro and ex vivo studies were included. The methodological quality was evaluated using the guidelines for reporting of preclinical studies on dental materials by Faggion Jr. Results: A total of 655 articles searched in various databases were initially scrutinized. Sevety one articles were chosen for quality analysis. The risk of bias was considered medium to high in most studies. The use of hydrofluoric acid (HF), silane and laser afforded the overall best results. HF and HF plus laser achieved significantly highest bond strength scores in felsdphatic porcelain, while laser was the best treatment in lithium disilicate ceramics. Conclusions: The most effective technique for bonding brackets on ceramic is dependent on the type of ceramic.

Effects of Novel versus Conventional Porcelain Surface Treatments on Shear Bond Strength of Orthodontic Brackets: A Systematic Review and Meta-Analysis

BACKGROUND

Despite the importance of identifying proper novel porcelain preparation techniques to improve bonding of orthodontic brackets to porcelain surfaces, and despite the highly controversial results on this subject, no systematic review or meta-analysis exists in this regard.

OBJECTIVE

To comparatively summarize the effects of all the available porcelain surface treatments on the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets (metal, ceramic, polycarbonate) bonded to feldspathic porcelain restorations. Search Methods. A search was conducted for articles published between January 1990 and February 2021 in PubMed, MeSH, Scopus, Web of Science, Cochrane, Google Scholar, and reference lists. Eligibility Criteria. English-language articles comparing SBS of feldspathic porcelain's surface preparation methods for metal/ceramic/polycarbonate orthodontic brackets were included. Articles comparing silanes/bonding agents/primers without assessing roughening techniques were excluded. Data Analysis. Studies were summarized and risk of bias assessed. Each treatment's SBS was compared with the 6 and 10 MPa recommended thresholds. Studies including comparator (HF [hydrofluoric acid] + silane + bonding) were candidates for meta-analysis. ARI scores were dichotomized. Fixed- and random-effects models were used and forest plots drawn. Egger regressions and/or funnel plots were used to assess publication biases.

RESULTS

Thirty-two studies were included (140 groups of SBS, 82 groups of ARI). Bond strengths of 21 studies were meta-analyzed (64 comparisons in 14 meta-analyses). ARIs of 12 articles were meta-analyzed (28 comparisons in 8 meta-analyses). Certain protocols provided bond strengths poorer than HF + silane + bonding: "abrasion + bonding, diamond bur + bonding, HF + bonding, Nd:YAG laser (1 W) + silane + bonding, CO₂ laser (2 W/2 Hz) + silane + bonding, and phosphoric acid + silane + bonding." Abrasion + HF + silane + bonding might act almost better than HF + silane + bonding. Abrasion + silane + bonding yields controversial results, being slightly (marginally significantly) better than HF + silane + bonding. Some protocols had controversial results with their overall effects being close to HF + silane + bonding: "Cojet + silane + bonding, diamond bur + silane + bonding, Er:YAG laser (1.6 W/20 Hz) + silane + bonding." Few methods provided bond strengths similar to HF + silane + bonding without much controversy: "Nd:YAG laser (2 W) + silane + bonding" and "phosphoric acid + silane + bonding" (in ceramic brackets). ARIs were either similar to HF + silane + bonding or relatively skewed towards the "no resin on porcelain" end. The risk of bias was rather low. Limitations. All the found studies were in vitro and thus not easily translatable to clinical conditions. Many metasamples were small.

CONCLUSIONS

The preparation methods HF + silane + bonding, abrasion + HF + silane + bonding, Nd:YAG (2 W) + silane + bonding, and phosphoric acid + silane + bonding (in ceramic brackets) might provide stronger bonds.

Assessment of Wettability and Contact Angle of Bonding Agent with Enamel Surface Etched by Five Commercially Available Etchants: An In Vitro Study

Background

The quantity and quality of the etching pattern produced by acids play a significant role in the wettability and contact angle of the adhesive with the enamel surface in orthodontics. The better the etch pattern, the more the surface energy of the enamel, better the penetration of the adhesive, which ultimately results in better bond strength. The present study aimed to evaluate the contact angle of the bonding agent with the enamel surface etched by five commercially available etchants and check if any difference existed between the five.

Materials and Methods

Twenty-five human maxillary and mandibular central incisors and premolars extracted for orthodontic or dental purposes were used in this study as samples. The teeth were allocated into five groups based upon the etchant used to etch the enamel surface. After the samples were etched, a hard tissue microtome was used to create thin slices of the enamel surface. The samples were then exposed to bonding agent Ormco Enlight. The bonding agent was released in the form of droplets onto the enamel slices mounted on a contact angle goniometer. The contact angle values were tabulated, and statistical analysis using the one-way ANOVA test was carried out.

Results

The contact angle measurements of the etchant group, DPI, were the lowest, while D-tech has the highest contact angle values. However, statistical analysis revealed no statistically significant difference between the contact angle measurements of the five groups included in the study.

Conclusion

No statistically significant difference existed between the five etchant groups included in the study. However, commercially available etchant DPI showed lesser contact angle and thus better wettability in comparison to other groups. Further elemental analysis and surface analysis are required to validate these results.

Evaluation of Time Consumption for Debonding Brackets Using Different Techniques: A Hospital-Based Study

Materials and Methods

A total of 80 human premolars were included in this study. The samples were first arranged following a standard protocol for bracketing and then debonded using the ultrasonic scaler (US), debonding plier (DP), ligature cutter (LC), and thermal method (TM). Depending on the technique applied for debonding, the specimens were randomly divided into four groups with 20 samples, each keeping a 1 : 1 ratio. During the debonding process, the time taken for each bracket removal was recorded using a stopwatch. To assess the difference in mean time required for debonding among the four techniques, one-way ANOVA test was applied along with Tukey's HSD to compare the two methods.

Results

The time range and the mean time required for the four techniques analyzed show that the DP method has the highest range of time needed for debonding with 0.97-2.56 seconds, while LC methods have the least time range taking 0.46 to 1.79 seconds. TM's mean time to debond is the highest at 1.5880 seconds. LC method has the lowest mean debonding time of 0.9880 seconds. The one-way ANOVA test has shown the mean debonding time required by the four techniques to be significantly different (p < 0.001). Tukey's HSD multiple comparisons also show that the mean time to debond using the LC method is substantially less than the other three methods (p < 0.001).

Conclusion

The mean debonding time for the TM was substantially the highest, followed by the US and DP. Debonding with the LC technique required the least time. This study shows some limelight towards the effectiveness of the LC method as it is the least time-consuming technique.

Orthodontic Attachment Adhesion to Ceramic Surfaces

Ceramic materials are constantly evolving, achieving good functionality and aesthetics. Bonding to ceramics may be difficult because of high toxicity procedures and risk of surface damage. The review aims to answer several research questions: Is there a golden standard for bonding to ceramic? Are there adhesives or types of photopolymerization lamps that produce a higher bond strength on certain types of ceramics rather than others? Articles focusing on the bonding process of orthodontic attachments to ceramic surfaces searched in Pubmed, Medline and Embase, published between 1990 and 2018 were revised. Exclusions concerned bonding to non-ceramic surfaces, bonding to ceramic surfaces that are not destined for orthodontics or laser usage. Forty-nine articles that matched the inclusion criteria were researched. The following categories of original research articles were compared and discussed: metallic brackets bonding to ceramic surfaces, ceramic brackets to ceramic surfaces, bonding to new types of ceramics, such as zirconia, lithium disilicate, different photopolymerisation devices used on bonding to ceramics. Some types of adhesive may achieve minimal bond strength (6-8 MPa) even on glazed ceramic. Ceramic surface preparation may be done by sandblasting or hydrofluoric acid (60s application and 9.6%) with generally similar results. Studies rarely show any statistical difference and there are reduced number of samples in most studies. Ceramic brackets show better adhesion to ceramic surfaces and the same bonding protocol is advised. A higher bond strength may lead to ceramic surface. Few studies focus on newer types of ceramics; additional research is necessary. There is no clear evidence that a certain type of photopolymerization device produces higher shear bond strength values.

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.