Plastic Brackets Research Articles

Measuring Device Detecting Impact Forces on Impact Rollers

This paper presents laboratory devices on which measurements were carried out to prove the validity of the assumption about the reduction in vibrations transmitted to the conveyor belt structure generated by the impact forces of falling material grains in the places of transfer or on the hoppers of conveyor belts. In order to limit damage to the conveyor belts caused by the impact of the sharp edges of material grains, conveyor belts are supported by impact rollers or impact rubber rods. A special modification of the fixed conveyor idler is presented, which consists of inserting plastic brackets into the structurally modified roller axle holders of the fixed conveyor idler. Measurements showed that the specially modified fixed conveyor idler resulted in a higher damping of up to 15% of the impact forces of the falling weight on the rubberized hoop of the impact roller shell compared to the conventional fixed conveyor idler design. Measurements carried out show that the effective vibration velocity values detected at the points where the impact roller axis fits into the fixed roller table holder are higher than when using plastic brackets, up to 6% for a 108-mm-diameter roller, compared to steel impact roller brackets.

The Reduction of Rotating Conveyor Roller Vibrations via the Use of Plastic Brackets

The Reduction of Rotating Conveyor Roller Vibrations via the Use of Plastic Brackets

Effect of Material and Pad Abrasion on Shear Bond Strength of 3D-Printed Orthodontic Brackets.

To investigate the effect of printing material and air abrasion of bracket pads on the shear bond strength of 3D-printed plastic orthodontic brackets when bonded to the enamel of extracted human teeth. Premolar brackets were 3D-printed using the design of a commercially available plastic bracket in two biocompatible resins: Dental LT Resin and Dental SG Resin (n = 40/material). 3D-printed brackets and commercially manufactured plastic brackets were divided into two groups (n = 20/group), one of which was air abraded. All brackets were bonded to extracted human premolars, and shear bond strength tests were performed. The failure types of each sample were classified using a 5-category modified adhesive remnant index (ARI) scoring system. Bracket material and bracket pad surface treatment presented statistically significant effects for shear bond strengths, and a significant interaction effect between bracket material and bracket pad surface treatment was observed. The non-air abraded (NAA) SG group (8.87 ± 0.64 MPa) had a statistically significantly lower shear bond strength than the air abraded (AA) SG group (12.09 ± 1.23 MPa). In the manufactured brackets and LT Resin groups, the NAA and AA groups were not statistically significantly different within each resin. A significant effect of bracket material and bracket pad surface treatment on ARI score was observed, but no significant interaction effect between bracket material and pad treatment was found. 3D-printed orthodontic brackets presented clinically sufficient shear bond strengths both with and without AA prior to bonding. The effect of bracket pad AA on shear bond strength depends on the bracket material.

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.

Seismic Performance of Internal Partition Walls with Slotted and Bracketed Head-Tracks

ABSTRACT This paper presents the concept, design, construction and seismic performance assessment of internal partition walls with novel slotted and bracketed head-track details. In the slotted head-track walls, the anchors connecting the wall to the slab above are intended to slide within the slot to accommodate the desired in-plane drifts. On the other hand, in the bracketed head-track walls, the story-drift demands are accommodated by sliding of the bolt and flexing of the plastic brackets attached to the slots. In this paper, bi-directional behaviour of a novel flexible bracket is experimentally characterised and a number of wall sub-assemblies with the slotted and bracketed connection details are tested under quasi-static cyclic loading to investigate their seismic performance. The walls with slotted details showed the first signs of damage requiring repair at 0.78% drift. In contrast, when brackets were attached to the slots, the wall remained intact up to 4% drift, demonstrating a superior seismic resiliency.

Color Stability of Various Plastic and Ceramic Brackets: An In Vitro Study

Introduction: The aim of this study was to evaluate color stability of various plastic and ceramic brackets after immersing in food solutions. Methods: Three plastic brackets and six ceramic brackets brands (three polycrystalline and three monocrystalline brackets) were selected. Ten brackets per brand were immersed in three dye solutions (red wine, coffee and curry). After immersing for one day, three days and seven days, color changes of the brackets were measured using a spectrophotometer (SpectrolinoTM). Color change, ΔE* was calculated based on the CIE L*, a* and b* system. Results: Plastic brackets, especially Silkon MTM showed the biggest color change in red wine, coffee and curry. 20/40TM bracket showed similar color change with plastic brackets despite that it is a polycrystalline bracket. Other polycrystalline brackets, ClarityTM advanced and VitrineTM, showed smaller color change than plastic but bigger than monocrystalline brackets. Monocrystalline brackets, RadianceTM and Inspire ICETM showed the smallest color change in all three solutions. Conclusions: Significant color change of esthetic brackets can occur based on the bracket composition, dye solution type and immersion time.

Analysis of Coating Loss from Coated Stainless Steel Orthodontic Wire

The leaching of metal ions from orthodontic appliances into the oral cavity is problematic for metal-allergic patients. Non-metal orthodontic appliances, such as plastic and ceramic brackets and elastomeric materials, have been clinically used and are effective for treatment of metal-allergic patients. However, only a few types of orthodontic wire are available for use in patients with metal allergies, thus restricting the establishment of orthodontic force systems in these patients. Wire surfaces can be coated with various substances to prevent leaching of metal ions. However, detachment of the coating may occur during orthodontic procedures, resulting in metal ion leaching from the substrate material. This study was performed to examine the resilience of various types of coated stainless steel wire to low pH, bending, and brushing. Wire surface characteristics were examined by stereomicroscopy and scanning electron microscopy. The degree of coating detachment due to bending of the wire was quantified by determining the change in the amount of metal ions eluted from the site of the bend immersed in hydrochloric acid. Exposure of the substrate metal by brushing was investigated by energy dispersive spectrometry. The results indicated that polyethylene naphthalate (PEN)-coated wire is resilient to bending, while gold (Au)-coated and titanium nitride (TiN)-coated wires are resilient to brushing.

Assessment of the Susceptibility of Aesthetic Orthodontic Brackets to Discoloration

The high aesthetic value of orthodontic appliance elements during treatment constitutes an important factor for an increasing number of adult patients. The aim of this study was to determine whether food dyes could significantly affect the color of both plastic and ceramic orthodontic brackets. Four brands of orthodontic brackets were investigated in the present study. Twenty-five samples of each kind were prepared. Five brackets of each series were stored in pure water, coffee, black tea and red wine for 1 h, 24 h, 7 days and 14 days. Total color change ΔE* of the samples was analyzed after storage with the use of the SpectroShade dental spectrophotometer (MHT, Verona, Italy) according to the CIE L*a*b* color scale. Correlations between bracket brand, kind of food dye and intensity of color change at the significance level p = 0.05 were investigated. After 1 and 24 h of incubation, water had the least influence on the color change of aesthetic orthodontic brackets, and tea had the greatest effect (p = 0.05). After 7 and 14 days of incubation of the samples, water still remained the environment influencing ΔE* change to the smallest extent, whereas storage in red wine changed the color of brackets to the significantly (p = 0.05) highest degree. The degree of discoloration of the assessed brackets depended on the type of material and the storage time in the environment of the individual food dyes (p = 0.05). The results of the present study show that, in the event of contact with food dyes, aesthetic orthodontic brackets discolor, the intensity of which can be influenced by the materials they are made of, the kind of food dye and the time of samples’ storage.

MRI compatibility of orthodontic brackets and wires: systematic review article

BackgroundBefore the magnetic resonance imaging (MRI) examination fixed orthodontic devices, such as brackets and wires, cause challenges not only for the orthodontist but also for the radiologist. Essentially, the MRI-safe scan of the fixed orthodontic tools requires a proper guideline in clinical practice. Therefore, this systematic review aimed to examine all aspects of MRI-safe scan, including artifact, thermal, and debonding effects, to identify any existing gaps in knowledge in this regard and develop an evidence-based protocol.MethodsThe Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement was used in this study. The clinical question in “PIO” format was: “Does MRI examination influence the temperature of the orthodontic devices, the size of artifacts, and the debonding force in patients who have fixed orthodontic bracket and/or wire?” The search process was carried out in PubMed, PubMed Central, Scopus, and Google Scholar databases. The search resulted in 1310 articles. After selection according to the eligibility criteria, 18 studies were analyzed by two reviewers. The risk of bias was determined using the Quality In Prognosis Studies tool.ResultsOut of the eligible 18 studies, 10 articles examined the heating effect, 6 were about the debonding effect, and 11 measured the size of artifact regarding brackets and wires. Considering the quality assessment, the overall levels of evidence were high and medium.The published studies showed that heating and debonding effects during MRI exposure were not hazardous for patients. As some wires revealed higher temperature changes, it is suggested to remove the wire or insert a spacer between the appliances and the oral mucosa. Based on the material, ceramic and plastic brackets caused no relevant artifact and were MRI-safe. Stainless steel brackets and wires resulted in susceptibility artifacts in the orofacial region and could cause distortion in the frontal lobe, orbits, and pituitary gland. The retainer wires showed no relevant artifact.ConclusionsIn conclusion, the thermal and debonding effects of the fixed orthodontic brackets and wires were irrelevant or resoluble; however, the size of the artifacts was clinically relevant and determined most significantly the feasibility of fixed brackets and wires in MRI examination.

Esthetics of Orthodontic Appliances: Objective Evaluation by Spectrophotometry vs Subjective Evaluation Using the Visual Analog Scale Method

In this study, we quantified the color of brackets and archwire appliances for an objective evaluation and investigated its relationship with subjective esthetic evaluation. Five types of commercially available brackets (ceramic brackets C1, C2, and C3; plastic brackets P1 and P2) and three types of archwires (coated nickel-titanium archwires W1, W2, and W3) were used. The reflectance (%) and color (lightness: L*, hue: a*, b*) of each sample were quantified using a spectrophotometer (n = 5). Fifteen combinations of brackets and archwires were used. The esthetic evaluation was performed using the visual analog scale (VAS) method, and responses were obtained from 30 laypersons and 15 orthodontists. The mean VAS score was calculated, and the relationship between the reflectance and color of the bracket and archwire was discussed. The reflectance and L* of the brackets showed significantly higher values for C3 and C1 than for the others and lower values for P1 and P2. The reflectance and L* of the archwire showed significant differences among all samples. There was a high positive correlation between the reflectance and L*. There were statistically significant positive correlations between the layperson and orthodontist groups, between the VAS score and reflectivity, and between VAS score and L*. Our results showed that as the lightness and reflectance of the brackets and archwires increased, the subjective evaluation concerning their esthetic value was higher. It is extremely difficult to evaluate esthetics despite the fact that patients' demands for esthetics have been increasing in recent years. If a method for evaluating esthetics is established, it should help in the development and selection of esthetic devices. The results of this study will facilitate the development of future study designs.

Management of mandibular incisor crowding with clear aligners and nickel titanium wires: A comparative study

Background: Esthetic orthodontic appliances such as esthetic labial appliances like plastic brackets, ceramic brackets, esthetic coated arch wires, lingual appliances and clear aligners are very popular among patients which are outcome of new advances in orthodontics. The present study compared treatment of mandibular incisor crowding with clear aligners and nickel titanim wires. Materials and Methods: 40 patients with mandibular incisal crowding was selected. Two groups were formed of both gender. First group (Group I) patients were treated with nickel- titanium arch wires and second group (group II) patients with clear aligners. Crowding was assessed using little’s irregularity index. The linear horizontal displacement of the anatomic contact points of mandibular anterior teeth is measured and added which denotes total irregularity score. Patients were recalled regularly at 4 weeks, 8 weeks and 12 weeks. Results: At baseline, mean score in first group was 2.94 mm and in second was 2.70 mm, at 4 weeks in first group was 1.68 mm and in second group was 1.50 mm, at 8 weeks in first group was 0.94 mm and in second group was 1.4 mm and at 12 weeks in first group was 0.64 mm and in second group was 0.56 mm. The difference was non- significant (p>0.05). The mean change in little’s irregularity index score at 4 weeks in first group was 1.28 mm and in second group was 1.21 mm, at 8 weeks was 0.75 mm in first group and 0.46 mm in second group and at 12 weeks was 0.37 mm in first group and 0.74 mm in second group. The difference was significant (p

Pain and removal force associated with bracket debonding: a clinical study.

Objective:Pain is a problem during bracket removal, and more comfortable treatment is needed. This study examined the association of pain with the removal force required for ceramic brackets, compared with metal and plastic brackets, to determine which removal method resulted in less pain and discomfort.Methodology:81 subjects (mean age, 25.1 years; 25 males and 56 females) were enrolled, from whom 1,235 brackets (407 ceramic, 432 plastic, and 396 metal) were removed. Measured teeth were distinguished at six segments. Pain was measured with a visual analogue scale (VAS) during the removal of each bracket. An additional grip was placed on the grips of debonding pliers with right-angled beaks; a mini loading cell sensor pinched by the grips was used to measure removal force during debonding. VAS and force values were statistically analyzed. The Kruskal–Wallis test followed by the Mann–Whitney U test with Bonferroni correction were performed for multiple comparisons; multiple regression analysis was also performed.Results:Forces in the upper and lower anterior segments were significantly smaller (p<0.05) than those in the other segments. Pain tended to be greater in the upper and lower anterior segments than in the posterior segments. In all segments, the removal force was greater for metal brackets than for plastic or ceramic brackets. Ceramic brackets caused significantly greater pain than plastic brackets for the upper and lower anterior segments. Debonding force was involved in the brackets, following adjustments for pain, upper left segment, age, and sex.ConclusionsPain and discomfort are likely to occur during bracket debonding.

Convenient Waveguide Technique for Determining Permittivity and Permeability of Materials

This article proposes a convenient technique for determining the permittivity and permeability of materials placed in a waveguide. Simplicity and repeatability of the method are achieved due to the utilization of contactless waveguide flanges and short-short-line (SSL) calibration technique. The grooves in the contactless flange prevent the electromagnetic field from leaking through the gap between the flanges even though misalignments exist. The SSL calibration uses a single line standard and two short standards. Since only one line standard is required, the test fixtures do not need to move during the calibration and measurement. With the help of contactless flanges and SSL calibration technique, the test fixtures could stay fixed in a plastic bracket. In addition, the line standard, the short standards, and the device under test (DUT) can be easily replaced without fastening screws. It is convenient when there are a large number of samples to be measured. The measured permittivity and permeability of polytetrafluoroethylene (PTFE) and carbonyl iron powders in the whole X-band showed the validity of the contactless flange and the accuracy of the SSL calibration technique.

Design of Plastic Injection Mould for Plastic Bracket

The side core pulling mechanism of “fixed mold lifer+T-type lift guide block” is adopted for the fixed mold of bracket, and the side core pulling mechanism of “angle pin+slide” and “angle pin+slide+T-type guide block” side core pulling mechanism is adopted for the movable mold of bracket. The gating system adopts the sub gate, the inner reinforcing rib is formed by moving mold insert, and the ejection system is the form of ejector pin+blade ejector pin. It provides a good reference for the design of similar moulds.

Effects of plastic bracket primer on the shear bond strengths of orthodontic brackets

Background/purposeTo assess the usefulness of plastic bracket primer (PBP) for improving the bond strength of plastic brackets (PBs) using three types of orthodontic brackets, including PBs, metal brackets (MBs), and ceramic brackets (CBs). Materials and methodsA total of 162 premolars were gathered and divided equally into six groups of 27. Three groups were tested with the application of PBP (PB+, MB+, and CB+), and three groups were tested without primer (groups PB-, MB-, and CB-). All the groups were bonded using BeautiOrtho Bond II self-etching adhesive. The shear bond strength (SBS) was measured and the bond failure mode was evaluated using the adhesive remnant index after debonding. ResultsThere were significant differences in the mean SBS between groups PB-, MB and CB-, between PB+ and CB+, and between MB+ and CB+. Group PB + had a significantly higher mean SBS than group PB-. The occurrence of bond failure at the enamel and adhesive interface was more frequent in groups PB+ and CB- than in group PB-; and in groups PB+ and CB + than in group MB+. ConclusionPlastic bracket primer can increase the bond strength of PBs to the level of metal brackets, but not to the level of ceramic brackets.

Effectiveness of low binding frictional materials: Evaluation of the binding frictional resistance of improved superelastic nickel-titanium alloy wires with different bracket combinations

Introduction: This study aimed to evaluate the binding frictional resistance of improved superelastic nickel- titanium alloy wires (ISW) with different bracket combinations and to verify the effectiveness of low binding frictional materials by applying them in orthodontic treatment. Materials and Methods: Straight stainless steel wire (SSW; 0.016 × 0.022-inch) and straight ISW (0.016 × 0.022- inch) were set to each displaced bracket, and the tensile resistance load was measured. The maximum tensile resistance load was statistically compared using the Tukey test. For exemplification, we treated a typical extraction case of Angle Class I crowding malocclusion with lip protrusion using lower binding frictional materials, which were selected based on tensile test results. Results: The SSW and metal bracket combination had the largest maximum tensile resistance load, and the ISW and metal slot-equipped plastic bracket combination had the smallest load (P &lt; 0.01). In a patient treated using lower binding frictional materials, the active treatment period was 9 months. Satisfactory patient results were obtained without using reinforced anchorage. Conclusions: Binding frictional resistance varies, depending on the archwire and bracket combination. In a multibracket appliance, selecting materials with as low a binding frictional resistance as possible may make a more effective treatment.

Variations in orthodontic bracket retention related to base design. Comparison of foil mesh and anchor pylons brackets

Aim of the study. To compare the shear bond strength of metal brackets with foil mesh (3M, Victory Series), one piece metal brackets (Cannon Ultra) and aesthetic plastic brackets (Cannon Ultra) and to evaluate the sandblasting effect on previously used metal bracket bases regarding their bonding ability. Materials and Methods.A total of seventy human third molars were divided into four groups, and brackets were bonded to the enamel using Transbond XT. After 24 hours of storage, brackets were debonded with Instron Universal Testing Machine® and shear bond strength was recorded. Metal brackets were sandblasted until all visible bonding material was removed from the bracket base and then the bonding procedure and shear bond testing were repeated. Shapiro-Wilk test was used to check normal distribution. Student’s t-test was used to compare the shear bond strength. Results. The shear bond strength of one-piece metal brackets is significantly bigger (18.93MPa) than metal brackets with foil mesh (12.53MPa). Metal brackets in general demonstrate better bonding properties than aesthetic plastic brackets (8.61MPa). There is no statistically significant difference in shear bond strength between new and re-used sandblasted brackets. Conclusions. One-piece brackets with anchor pylons demonstrate better bonding properties but there is a higher risk of enamel damage during debonding of re-used sandblasted brackets.

Evaluation of mechanical properties of esthetic brackets.

Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing.

Influence of the bracket on bonding and physical behavior of orthodontic resin cements.

The aim of the study is to determine the influence of the type of bracket, on bond strength, microhardness and conversion degree (CD) of four resin orthodontic cements. Micro-tensile bond strength (µTBS) test between the bracket base and the cement was carried out on glass-hour-shaped specimens (n=20). Vickers Hardness Number (VHN) and micro-Raman spectra were recorded in situ under the bracket base. Weibull distribution, ANOVA and non-parametric test were applied for data analysis (p<0.05). The highest values of ή as well as the β Weibull parameter were obtained for metallic brackets with Transbond™ plastic brackets with the self-curing cement showing the worst performance. The CD was from 80% to 62.5%.

Changes in physical properties of new, non-BPA containing, polymeric orthodontic bracket materials over time: A 2-year clinical study

PurposeThe purpose of this study was to develop new, biocompatible plastic brackets which are esthetic and do not release bisphenol A (BPA). Materials and methodsIn this study, brackets were fabricated using four different materials: polyacetal (POM), polyester (PE) and polycarbonate (PC), and a filled polycarbonate (PCF) as a control. Clinical testing using 46 subjects was conducted to evaluate changes in their physical properties (fracture frequency of bracket wings, strength of bracket wings and bracket wear) over 2 years (at baseline, year 1 and year 2) to assess the suitability of these materials for clinical use. Results(1) PE brackets were the only group that showed fracture in the fracture frequency test. (2) POM showed low wear rates. (3) POM showed great variation in bracket wing strength, but no statistical significant difference was observed between PE and POM. ConclusionThis 2-year clinical study concludes that POM and PE are more promising materials for the fabrication of orthodontic brackets than PCF.