Influence of Friction Resistance on Expression of Superelastic Properties of Initial NiTi Wires in "Reduced Friction" and Conventional Bracket Systems

Applications of nanotechnology in orthodontics: a comprehensive review of tooth movement, antibacterial properties, friction reduction, and corrosion resistance

Nanotechnology has contributed important innovations to medicine and dentistry, and has also offered various applications to the field of orthodontics. Intraoral appliances must function in a complex environment that includes digestive enzymes, a diverse microbiome, mechanical stress, and fluctuations of pH and temperature. Nanotechnology can improve the performance of orthodontic brackets and archwires by reducing friction, inhibiting bacterial growth and biofilm formation, optimizing tooth remineralization, improving corrosion resistance and biocompatibility of metal substrates, and accelerating or decelerating orthodontic tooth movement through the application of novel nanocoatings, nanoelectromechanical systems, and nanorobots. This comprehensive review systematically explores the orthodontic applications of nanotechnology, particularly its impacts on tooth movement, antibacterial activity, friction reduction, and corrosion resistance. A search across PubMed, the Web of Science Core Collection, and Google Scholar yielded 261 papers, of which 28 met our inclusion criteria. These selected studies highlight the significant benefits of nanotechnology in orthodontic devices. Recent clinical trials demonstrate that advancements brought by nanotechnology may facilitate the future delivery of more effective and comfortable orthodontic care.

Deflection of tandem archwire in a specific self-ligating metal bracket system: an in vitro study

The aim of this study was to quantify the force exerted by tandem archwires in a specific system of passive self-ligating bracket. Forty-eight thermo-activated nickel-titanium orthodontic archwires were separated into four groups (n = 12): G1 - two .014" + .014" round archwires; G2 - two .014" + .016" round archwires; G3 - .014" x .025" rectangular archwire; and. G4 - .016" x .022" rectangular archwire. Brackets were fixed onto teeth 1.5 to 2.5 using a device that represented the upper teeth, maintaining an interbracket distance of 6.0 mm. The deflection tests were performed using the structure representative of tooth 1.1 as support on the Instron testing machine at a speed of 2.0 mm/min. The archwires were evaluated at deflections of 0.5 mm, 1.0 mm, and 1.5 mm. The data were analyzed by a generalized linear model, considering values at different deflections as repeated measurements in the same experimental unit (α = 0.5%). At 0.5 mm, higher forces were observed in G2 and G3, which did not differ significantly (p > 0.05). The lowest force was observed in G4 (p < 0.05). At 1.0 mm and 1.5 mm, the highest force was observed in G3, followed by G4 and G2 (p < 0.05). The lowest force was observed in G1 (p < 0.05). In general, tandem archwires (same or different calibers) in a specific passive self-ligating bracket exerted lower force when compared with rectangular archwires.

Application of Nanotechnology in Orthodontic Materials: A State-of-the-Art Review

Nanotechnology refers to the science that manipulates matter at molecular and atomic levels, and studies matter at the nanoscale level to detect and exploit the useful properties that derive from these dimensions; materials with components less than 100 nm in at least one dimension are called nanomaterials. Nanotechnology is applied in many fields, such as medicine (nanomedicine) and dentistry (nano-dentistry). The purpose of these innovations and research in this field is to improve human life and health. This article aims to summarize and describe what the most recent and known innovations of nanotechnology in dentistry are, focusing on and paying particular attention to the branch that is orthodontics, and on the application of new nanomaterials in the realization, for example, of orthodontic elastomeric ligatures, orthodontic power chains, and orthodontic miniscrews. We also address a very important topic in orthodontics, which is how to reduce the friction force.

EFFECTS OF THE INSERTION OF AN ARCHWIRE THIN-WALLED SLEEVE IN ACCELERATING THE CANINE’S TRANSLATION

In sliding mechanics, resistance to sliding (RS), including friction, binding, and notching, generated at a wire-bracket interface has a bearing on the force transmitted to the teeth and further influences the biomechanical behavior associated with tooth movement efficiency. Objective: This study aimed to propose and verify the insertion of a rectangular thin-walled sleeve between an archwire and a bracket to minimize the resistance effect on the biomechanical behavior of tooth movement by using the finite element (FE) method. Material and methods: A 3D FE solid model was constructed and composed of mandibular dentitions, including the surrounding tooth-supporting structures and fixed self-ligating appliances. The translation of the left mandibular canine was simulated (0.1[Formula: see text]mm and 0.3[Formula: see text]mm) from the labial side to the lingual side with or without the thin-walled sleeve by using eight kinds of archwires with various dimensions and cross-sections by FE methods. Results: FE analysis indicated that the canine’s maximum initial displacement and the highest periodontal ligament (PDL) von Mises stress were mainly influenced by the orthodontic wire and the insertion of the thin-walled sleeve. Without the thin-walled sleeve, rectangular archwires could initiate a more optimal tissue response than round archwires. However, the insertion of the thin-walled sleeve between the small round archwire and the bracket significantly presented the most optimal biological responses in all of the cases. Conclusion: FE results revealed that the insertion of a thin-walled sleeve in a small round archwire and a bracket could have a positive influence on final tooth movement.

Application of a Molybdenum and Tungsten Disulfide Coating to Improve Tribological Properties of Orthodontic Archwires

Coatings incorporating nanoparticles of molybdenum and tungsten disulfide (MoS₂ and WS₂)-known for their lubricating properties-are applied to orthodontic stainless steel wires to verify if there is an improvement in terms of tribological properties during the sliding of the wire along the bracket. To simulate in vitro sliding of the wire along the bracket and evaluate friction 0.019 × 0.025 inches orthodontic stainless steel (SS) wires were subjected to the application, by electrodeposition, of Ni, Ni + MoS₂, and Ni + WS₂. The samples produced were analyzed with scanning electron microscopy and assessment of resistance to bending. Thirty-two test conditions have been analyzed, arising from the combination of four types of coatings (SS bare wires and strings with three types of coating), two types of self-ligating bracket (Damon Q, Ormco and In-Ovation R, GAC International), two bracket-wire angles (0° and 5°), two environments (dry and wet). Analyses carried out on the samples show acceptable coatings incorporating MoS₂ and WS₂ and a resistance of coatings after a minimum bending. In "dry conditions" a statistically significant decrease in friction occurs for wires coated with MoS₂ and WS₂ if associated with the In-Ovation bracket. In "wet conditions" this decrease is observed only in isolated test conditions. Analysis of the wires after sliding tests show little wear of the applied coatings. Nanoparticles are acceptable and similar in their behavior. Improvements in terms of friction are obtained pairing coatings incorporating MoS₂ and WS₂ with the In-Ovation bracket in dry conditions.

Evaluation of the mechanical properties and surface topography of as-received, immersed and as-retrieved orthodontic archwires

Background and aims

This experimental study mainly aims at comparing the most important mechanical properties of the new orthodontic archwires, those immersed in fluorinated solution, the as-retrieved ones and the intra-oral used ones.

Methods

A total of 270 arch wires were tested, using tensile testing and three-point bending tests. The tested archwires were made of Stainless Steel, Nickel Titanium, Beta-Titanium and physiognomic covered Nickel Titanium. The tested archwires were subjected to three types of treatments: immersion into fluorinated solution, immersion into carbonated drinks and intra-oral use.

Results

The immersion caused variations of the activation and deactivation forces of all arch wires. The most affected arch wires, in terms of bending characteristics, were the intra-oral used ones.

Conclusions

The alteration of mechanical properties of the orthodontic arch wires by their immersion into fluorinated solutions and soft drinks could not be statistically demonstrated.

[Three-dimensional finite element analyses of the deep wedge-shaped defective premolars restored with different methods]

OBJECTIVE

The objective of this paper is to analyze the stress distribution in the deep wedge-shaped defective mandibular first premolars restored with different methods.

METHODS

Three-dimensional finite element models of mandibular first premolar with deep wedge-shaped defect were created. The model, which was untreated after root canal treatment, served as the control group. Then, according to different treatment designs, four experimental groups were established as follows: resin filling (A), post restoration after resin filling (B), crown restoration after resin filling (C), and post and crown restoration after resin filling (D). Four different post materials were then chosen for establishing the subgroup models: fiber post (B1, D1), AuPd post (B2, D2), pure Ti post (B3, D3), and CoCr post (B4, D4). A force of 100 N was applied at a 30° angle on the buccal-inclined surface near the top of the buccal cusp. The maximum principal stress and Von Mises stress were investigated using finite element analysis software.

RESULTS

1) For the control group, the maximum principal stress and Von Mises stress of the residual dentine were the same as those of the tip of the defect. 2) Compared with the control group, the maximum principal stress and Von Mises stress of groups A, B, C, and D decreased greatly (P<0.05). The maximum principal stress and Von Mises stress of groups C and D with crowns were similar. The maximum principal stress and Von Mises stress of the post-dentine surface of groups B and D with fiber post were less than those in the cast metal post models (P<0.05). 3) The displacement of the buccal cusp of group A was similar to that of the control group (P>0.05) and larger than those in groups B, C, and D (P<0.05).

CONCLUSIONS

It is necessary for deep wedge-shaped defective teeth to be treated with full crowns, but a post is not necessary. If a post is used, fiber post with elastic modulus closer to the dentine is more suitable than metal post.
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Evaluation of the force generated by gradual deflection of orthodontic wires in conventional metallic, esthetic, and self-ligating brackets

Objective:

The purpose of this study was to evaluate the deflection forces of Nitinol orthodontic wires placed in different types of brackets: metallic, reinforced polycarbonate with metallic slots, sapphire, passive and active self-ligating, by assessing strength values variation according to gradual increase in wire diameter and deflection and comparing different combinations in the different deflections.

Material and Methods:

Specimens were set in a clinical simulation model and evaluated in a Universal Testing Machine (INSTRON 3342), using the ISO 15841 protocol. Data were subjected to One-way ANOVA, followed by Tukey tests (p<0.05).

Results:

Self-ligating brackets presented the most similar behavior to each other. For conventional brackets there was no consistent behavior for any of the deflections studied.

Conclusions:

Self-ligating brackets presented the most consistent and predictable results while conventional brackets, as esthetic brackets, showed very different patterns of forces. Self-ligating brackets showed higher strength in all deflections when compared with the others, in 0.020-inch wires.

Load Deflection Characteristics of Nickel Titanium Initial Archwires

OBJECTIVES

The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs.

MATERIALS AND METHODS

This study tested three wire designs namely copper nickel titanium (CNT), nickel titanium (NiTi), and multi-strand NiTi (MSNT) archwires engaged in passive self-ligating (PSL) brackets, active self-ligating (ASL) brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length) were recorded. Two-way ANOVA and Tukey's test were used at P <0.05 level of significance.

RESULTS

Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force.

CONCLUSION

With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly.