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To improve the efficiency of strength verification of EWIS (Electrical Wiring Interconnection Systems) brackets, this thesis simplified the model of the EWIS bracket fixing harness, screened the extreme points of load of various brackets in the designated area of the aircraft, and determined the strength compliance of EWIS bracket at the extreme points of load. Therefore, it could quickly determine whether the strength of other similar brackets in the same area meets the requirements.

The developments in materials science and engineering, especially in the field of composites and polymers, have extended the scope of application of such materials in modern industrial construction. This article presents polyamide/ aluminium helping hand brackets, designed for use in rainscreens (a.k.a. ventilated façades ) and metal and glass systems. The main purpose of this study was to assess the loadbearing capacity, safety and durability of these elements through laboratory tests and numerical analyses. The laboratory tests were carried out on a three-dimensional test stand. Boundary conditions and the applied loading represented real conditions on the façade (e.g. a typical wind pressure load acting on the façade was used). Next, the experimental results were used to build a representative numerical model. Finite Element analysis was utilised to obtain a true representation of the actual behaviour of the analysed brackets subjected to various loads, taking into account the aluminium/ polyamide interaction. Constitutive behaviour of both materials, polyamide and aluminium alloy, was represented by a linear elastic model. The proposed modelling methodology was validated through full-scale load tests up to failure. The numerical model can be further used to predict the stress and strain fields in newly designed brackets subjected to any type of loading.

We prove that a pair of Feigin-Odesskii Poisson brackets on \\({\\mathbb P}^4\\) associated with elliptic curves given as linear sections of the Grassmannian \\(G(2,5)\\) are compatible if and only if this pair of elliptic curves is contained in a del Pezzo surface obtained as a linear section of \\(G(2,5)\\).

The formula ⋆ mod ō ( ħ k ) of Kontsevich’s star-product with harmonic propagators was known in full at ħ k ⩾6 since 2018 for generic Poisson brackets, and since 2022 also at k = 7 for affine brackets. We discover that the mechanism of associativity for the star-product up to ō ( ħ 6 ) is different from the mechanism at order 7 for both the full star-product and the affine star-product. Namely, at lower orders the needed consequences of the Jacobi identity are immediately obtained from the associator mod ō ( ħ 6 ), whereas at order ħ 7 and higher, some of the necessary differential consequences are reached from the Kontsevich graphs in the associator in strictly more than one step.

This study aims to assess the ion release (Ni, Cr) and surface roughness of metal (M), self-ligating (SL), and ceramic (C) orthodontic brackets after exposure to simulated gastric acid (pH 1.5, pH 3.0) and artificial saliva (pH 7.0). A total of 198 brackets, metal brackets (M) (n = 66) self-ligating (SL) (n = 66), and ceramic brackets (C) (n = 66) were used in this study. Gastric solutions mimicking human gastroesophageal reflux with a pH of 1, 5 or 3 and as a control group pH of 7 (artificial saliva) were used. All specimens were immersed in test solutions for 30 min, 24 h, and 1 month (n = 22 per group). Inductively coupled plasma-mass spectrometry (ICP-MS) measured ion release, while an optical profilometer assessed surface roughness. Data were analyzed using One-way ANOVA and t-tests (p < 0.05). Ni and Cr ion release peaked at 24 h and decreased by 1 month (p < 0.05). SL brackets released the most ions, particularly in acidic conditions (p < 0.05). Surface roughness was highest at 24 h, then decreased (p < 0.001), with M brackets showing the greatest roughness and C brackets the lowest (p < 0.001). M and SL brackets had the highest roughness at pH 1.5, while C brackets peaked at pH 3.0 (p < 0.001). Acidic conditions significantly impact ion release and surface roughness. Ceramic brackets may be advantageous for patients with reflux disease, offering reduced corrosion and surface alterations.

Objective This study aimed to evaluate enamel surface integrity and time consumed during residual cement removal after bracket debonding using different adhesive removal burs with and without a dental loupe. Material and Methods Sixty human-extracted premolars were collected, cleaned, mounted, and prepared for orthodontic bracket bonding. Teeth were randomly divided into three main groups ( n  = 20) based on the adhesive removal method: tungsten carbide system (TC), sof-lex discs system (SD), and diamond system (DB) groups. Then, each group was subdivided into two subgroups (naked eye and magnifying loupe subgroups). The brackets were bonded and then debonded after 24 h, and the Adhesive Remnant Index (ARI) was assessed. The adhesive remnants were removed by different systems, and the final polishing was performed by Silicone OneGloss. The enamel surface roughness was evaluated before bracketing (T0), after residual cement removal (T1), and finally after polishing (T2) using surface Mitutoyo SJ-210 profilometry and Scanning Electron Microscopy (SEM) to determine the Enamel Damage Index (EDI) score. The time consumed for adhesive removal was recorded in seconds. Results The Kruskal Wallis test showed a statistically significant difference in roughness values at T1 compared to T2 between subgroups ( p  < 0.001). When comparing EDI at T1 and T2, the Kruskal–Wallis H-test showed statistically significant differences in all subgroups. The pairwise comparisons revealed that EDI scores showed a statistically significant difference at T1 and T2 between DB vs. TC and SD ( p  = 0.015) but not between TC vs. SD ( p  = 1.000), indicating the highest roughness value observed in the DB group. The time for cement removal was significantly shorter in the magnifying loupe group than in the naked eye group and was shortest with the TC group, whereas the time was the longest with the DB group ( p  < 0.05). Conclusion All three systems were clinically satisfactory for residual orthodontic adhesive removal. However, TC system produced the lowest enamel roughness, while the DB system created the greatest. The polishing step created smoother surfaces regardless of the systems used for resin removal.

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.

Objective This study aimed to evaluate the effectiveness of biting on a cotton roll in reducing pain during metal bracket removal using a Weingart plier compared with the conventional method. Methods This two-arm, parallel-group, randomized controlled trial included 36 patients (11 males and 25 females) with a mean age of 20.5 ± 3.08 years (range: 16–25 years). The study was conducted among patients who had completed orthodontic treatment with a fixed appliance using MBT prescription 0.022-inch metal brackets featuring a single-mesh base (Pinnacle®, MBT compatible 0.022, OrthoTechnology™, Florida, USA), and they were referred for metal bracket debonding. Brackets were removed using a Weingart plier, and participants were randomly assigned to one of two groups: the open-mouth group and the biting-on-a-cotton-roll group. Pain intensity was assessed for each tooth using a visual analog scale (0–100 mm) immediately after each bracket removal. Pain levels were compared between the two groups, between the upper and lower jaws, and across sexes. Results Patients in both groups reported pain levels ranging from mild to mild–moderate, with lower mean pain levels observed in the biting-on-a-cotton-roll group compared with the open-mouth group. Significant differences in mean pain scores were found between the open-mouth group and biting-on-a-cotton-roll group in the upper and lower incisors (13.61 and 13.19, P < 0.001, respectively), upper and lower canines (4.03 and 3.61, P < 0.001, respectively), and upper and lower premolars (12.78 and 11.11, P < 0.001, respectively). No significant differences in pain perception were observed between males and females across all regions (P > 0.05). Conclusions Biting on a cotton roll significantly reduces pain during metal bracket debonding in the upper and lower incisor regions. The anterior regions of both jaws exhibit increased sensitivity to pain during the debonding procedure, whereas no differences in pain perception were observed between male and female patients.

Background Biofilm formation on orthodontic brackets is a significant concern due to its implications on oral hygiene, caries development, and periodontal health. The choice of bracket material may influence biofilm adherence and growth. This study evaluates biofilm formation on different orthodontic bracket materials to identify the least biofilm-retentive options. Materials and Methods A total of 60 orthodontic brackets, divided into three groups based on material type—metallic (n=20), ceramic (n=20), and composite resin (n=20)—were tested. Artificial saliva was used to mimic oral conditions, and Streptococcus mutans was selected as the primary biofilm-forming bacterium. Brackets were incubated for 48 hours at 37°C, after which biofilm quantification was performed using crystal violet staining and spectrophotometric analysis at 595 nm. Statistical analysis was conducted using ANOVA to compare biofilm formation across groups. Results The mean optical density (OD) values for biofilm formation were as follows: metallic brackets (0.25 ± 0.05), ceramic brackets (0.42 ± 0.08), and composite resin brackets (0.58 ± 0.07). Metallic brackets demonstrated the lowest biofilm formation, which was statistically significant compared to ceramic and composite resin brackets (p < 0.05). Ceramic brackets showed moderate biofilm formation, while composite resin brackets exhibited the highest levels of biofilm accumulation. Conclusion Metallic brackets are less conducive to biofilm formation compared to ceramic and composite resin brackets, making them a preferable choice for minimizing biofilm-related complications during orthodontic treatment. These findings emphasize the importance of material selection in orthodontic practice to promote better oral health outcomes. BJMS, Volume: 24. Supplementary Issue 2025, Page : 69-72

Enamel demineralisation can occur as a side effect during orthodontic treatment with fixed appliances. This study aimed to evaluate the efficacy of the self-assembling peptide P 11 -4 for remineralisation combined with fluorides, compared to application of fluoride varnish alone. De- and remineralisation was assessed by Quantitative light-induced fluorescence (QLF). Orthodontic brackets were bonded on 108 human enamel samples and white spot lesions were created. The samples were allocated randomly into three groups: Group I received no treatment, group II had a single application of fluoride varnish (22,600 ppm), and group III was treated with P 11 -4 following a single application of fluoride varnish. Quantitative light-induced fluorescence (QLF) measurements were performed at baseline, after demineralisation and after storage in remineralisation solution for 7 and 30 days. Non-parametric tests (Kruskal–Wallis test and Friedman test) were used for further analysis. After demineralisation, all samples showed a median ΔF -9.38% ± 2.79. After 30 days median ΔF values were as followed: group I = -9.04% ± 2.51, group II = -7.89 ± 2.07, group III = -6.08% ± 2.79). The median ΔF values differed significantly between all groups at all investigation times (p < 0.00001). Application of P 11 -4 with fluoride varnish was superior to the use of fluorides alone for remineralisation of enamel adjacent to brackets.