Conventional Stainless Steel Brackets Research Articles

Torque expression of superelastic NiTi V-Slot and conventional stainless steel orthodontic bracket-archwire combinations - A finite element analysis

BackgroundTo investigate the torque expression of conventional stainless steel (SS) brackets in combination with rectangular SS archwires and nickel-titanium (NiTi) V-slot brackets in combination with V-shaped NiTi archwires using finite element analysis (FEA). MethodsCAD models were created for a conventional bracket and rectangular archwires with dimensions of 0.018″x0.025″ and 0.019″x0.025″, and for a V-slot bracket and V-shaped archwires with heights of 0.55 mm, 0.60 mm and 0.70 mm. FEA was performed using Ansys 2022R2 software to assess the forces and moments during simulated torsion of the archwires in the brackets between 0° and 25° with varying interbracket distances and free path lengths. ResultsThe V-slot bracket-archwire combination exhibited force transmission and moment generation within 1° of torsion. The transmissible force increased with the torsion angle, but showed an upper limit of about 13–14 Nmm. The SS bracket-archwire combination showed negligible forces and moments for simulated torsion between 0° and 15°. At torsions of 25°, moments of 12 Nmm and 14 Nmm occurred for the 0.018″x0.025″ and 0.019″x0.025″ archwire dimensions, respectively. ConclusionsThe V-slot bracket-archwire combination is effective in expressing torque and preventing both over- and under-activation. Conventional bracket-archwire combinations showed torsional losses due to play between 10 and 15°, depending on the dimensions of the respective archwire, and no upper torsional moment limit.

Evaluation of the effects of different bracket types on the detection of interproximal enamel caries using periapical radiography

Aim: During orthodontic treatment, dental materials can affect the imaging of caries lesions. Material density and X-ray beam attenuation play important roles in this imaging. This study aims to evaluate the artifacts that are caused by brackets made of different materials and affect the visibility of International Caries Detection and Assessment System (ICDAS) code 5 caries. Methodology: One premolar tooth with ICDAS code 5 caries was examined. Eight periapical radiographs were taken: one without a bracket and seven with different types of brackets (composite with metal slot, self-ligating ceramic, monocrystalline ceramic, polycrystalline ceramic, zirconium, self-ligating stainless steel, and conventional stainless steel). The gray values of the caries region were evaluated using Fiji software (version 1.53f, National Institutes of Health, USA) on periapical radiographs. Results: Conventional stainless steel and self-ligating stainless steel brackets increased the radiopacity of the outer half of the enamel (E1). When these brackets were present, the gray values changed by -13.63633 (p = .026) and -16.38967 (p = .006), respectively. There was no statistically significant difference in column B due to the brackets. However, numerically, the gray value changes were similar to those in column A. Conclusion: Orthodontic brackets affect the evaluation of periapical images. Ceramic brackets provide more advantages than stainless steel brackets for radiographic imaging. How to cite this article: Karabiber G, Arsan B, Kocaer AF. Evaluation of the effects of different bracket types on the detection of interproximal enamel caries using periapical radiography. Int Dent Res 2023;13(2):83-89. https://doi.org/10.5577/idr.2023.vol13.no2.6 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Evaluation of the frictional resistance between different bracket types, archwires and ligation materials: An in-vitro study

In orthodontic treatment, brackets need to slide along the archwire to allow for alignment of the teeth. The lesser the friction between the bracket and the archwire, the easier it is to align the teeth and the lighter the forces required to make such movements. In recent years, patients’ esthetic demands have driven the field of orthodontics to find alternatives to conventional stainless steel bracket systems. While ceramic brackets meet the esthetic demands, their inferior frictional characteristics have always been an issue for orthodontists.The present in-vitro research study evaluates and compares the frictional resistance between various types of brackets, archwire materials and ligation methods. The purpose of the study was to equate the frictional resistance among 12 different groups using the universal testing machine, so as to recognize the factors involved in the in-vitro appraisal of resistance to sliding (RS) and inferring their clinical implications. In this study, 120 pre-adjusted edgewise upper central incisor brackets with MBT 0.022″ slot were used, which included 40 standard metal brackets, 40 ceramic brackets, 20 self-ligating metal brackets and 20 self-ligating ceramic brackets. 0.019″ x 0.025″ SS (stainless steel) archwires, esthetic archwires, Teflon-coated ligatures and conventional elastic modules to ligate the archwire to the brackets except in self-ligating brackets, were used. The average frictional resistance of Group A10 was the minimum succeeded by A9, A12, A4, A11, A8, A3, A7, A2, A6, A1 and A5. In the comparison of the mean frictional resistance of 12 different groups, the ANOVA test showed noticeably different frictional resistance amongst the groups (F=745.80, P< 0.001). Self-ligating metal bracket combinations with different archwires showed a significantly smaller magnitude of friction than self-ligating ceramic, metal and ceramic bracket combinations. Teflon-coated ligature combinations possess less friction in comparison with conventional elastomeric module combinations.

Antibacterial properties and abrasion-stability: Development of a novel silver-compound material for orthodontic bracket application.

Bacteria-induced white spot lesions are a common side effect of modern orthodontic treatment. Therefore, there is aneed for novel orthodontic bracket materials with antibacterial properties that also resist long-term abrasion. The aim of this study was to investigate the abrasion-stable antibacterial properties of anewly developed, thoroughly silver-infiltrated material for orthodontic bracket application in an in situ experiment. To generate the novel material, silver was vacuum-infiltrated into asintered porous tungsten matrix. Atooth brushing simulation machine was used to perform abrasion equal to 2years of tooth brushing. The material was characterized by energy dispersive X‑ray (EDX) analysis and roughness measurement. To test for antibacterial properties in situ, individual occlusal splints equipped with specimens were worn intraorally by 12periodontal healthy patients for 48 h. After fluorescence staining, the quantitative biofilm volume and live/dead distribution of the initial biofilm formation were analyzed by confocal laser scanning microscopy (CLSM). Silver was infiltrated homogeneously throughout the tungsten matrix. Toothbrush abrasion only slightly reduced the material's thickness similar to conventional stainless steel bracket material and did not alter surface roughness. The new silver-modified material showed significantly reduced biofilm accumulation in situ. The effect was maintained even after abrasion. Apromising, novel silver-infiltrated abrasion-stable material for use as orthodontic brackets, which also exhibit strong antibacterial properties on in situ grown oral biofilms, was developed. The strong antibacterial properties were maintained even after surface abrasion simulated with long-term toothbrushing.

Comparative Evaluation of Microleakage Under APC Plus, APC Flash-Free and Conventional Stainless Steel Brackets: An In Vitro Study

Aim: The aim of the study was to compare and evaluate the microleakage under the Adhesive Precoated Plus (APCP), APC Flash-Free (APCF), and conventional stainless steel (SLS) brackets on the occlusal and gingival sides of the bracket base. Materials and Methods: 66 extracted premolar teeth were collected and divided equally into 3 groups. Bonding was done with APCP, APCF, and conventional SLS brackets using Transbond XT. After bonding, the samples were stored in a distilled water and thermocycled for 3000 cycles, followed by immersion in a 2% methylene blue for 24 h. After cleaning, the teeth were mounted in acrylic and sectioned longitudinally at about the center of the bracket in a buccolingual direction. Microleakage was recorded using a stereomicroscope. Results: Kruskal–Wallis H test showed a significant difference ( P < .005) in the microleakage scores between the 3 groups. Mann–Whitney U test showed a significant difference between group 1 to group 2 and group 1 to group 3 ( P < .005) and an insignificant difference between group 2 and group 3 on the occlusal side ( P = .116) and on the gingival side ( P = .063). Conclusion: Conventional SLS bracket group exhibited greater microleakage scores at both occlusal and gingival sides, when compared with APCP and APCF groups.

Orthodontic appliances and MR image artefacts: An exploratory in vitro and in vivo study using 1.5-T and 3-T scanners.

PurposeThe aim of this study was to assess the artefacts of 12 fixed orthodontic appliances in magnetic resonance images obtained using 1.5-T and 3-T scanners, and to evaluate different imaging sequences designed to suppress metal artefacts.Materials and MethodsIn vitro, study casts of 1 adult with normal occlusion were used. Twelve orthodontic appliances were attached to the study casts and scanned. Turbo spin echo (TSE), TSE with high readout bandwidth, and TSE with view angle tilting and slice encoding for metal artefact correction were used to suppress metal artefacts. Artefacts were measured. In vivo, 6 appliances were scanned: 1) conventional stainless-steel brackets; 2) nickel-free brackets; 3) titanium brackets; 4) a Herbst appliance; 5) a fixed retainer; and 6) a rapid maxillary expander. The maxilla, mandible, nasopharynx, tongue, temporomandibular joints, and cranial base/eye globes were assessed. Scores of 0, 1, 2, and 3 indicated no artefacts and minor, moderate, and major artefacts, respectively.ResultsIn vitro, titanium brackets and the fixed retainer created minor artefacts. In vivo, titanium brackets caused minor artefacts. Conventional stainless-steel and nickel free brackets, the fixed retainer, and the rapid maxillary expander caused major artefacts in the maxilla and mandible. Conventional stainless-steel and nickel-free brackets caused major artefacts in the eye globe (3-T). TSE with high readout bandwidth reduced image artefacts in both scanners.ConclusionTitanium brackets, the Herbst appliance, and the fixed retainer caused minor artefacts in images of neurocranial structures (1.5-T and 3-T) when using TSE with high readout bandwidth.

Finite element analysis of torque induced orthodontic bracket slot deformation in various bracket-archwire contact assembly

Background and ObjectivesOrthodontic fixed appliance therapy involves alignment of teeth through the bracket and archwires. The archwire twist (torque) imparts significant forces inside the bracket slot in refining the teeth position at the end of treatment. The objective of this in- silico study was to evaluate the torque induced bracket slot deformation in the commonly used 0.018 inch (") and 0.022" conventional Stainless Steel (SS) brackets with clinically relevant archwires during various angles of twist. MethodsSS maxillary central incisor brackets of 0.018" width × 0.022" depth (0.457 mm × 0.558 mm) and 0.022" width × 0.028" depth (0.558 mm × 0.711 mm) were used. The SS archwires of 0.016" width × 0.022" depth (0.406 mm × 0.558 mm), 0.017" width × 0.025" depth (0.431 mm × 0.635 mm), 0.019" width × 0.025" depth (0.482 mm × 0.635 mm) and 0.021" width × 0.025" depth (0.533 mm × 0.635 mm) were engaged in the respective bracket slots. The assembled bracket-archwire Finite Element (FE) models were constructed. The archwire torque, the top, middle and bottom slot deformations (TSD, MSD, BSD) were obtained for the bracket-archwire combinations for various angles of archwire twist using FE Analysis (FEA). ResultsThe torque, TSD, MSD and BSD for 30o twist of 0.016" × 0.022" archwire in 0.018" slot were 28.13 Nmm, 35.71 µm, 21.51 µm and 15.67 µm respectively, and for 0.017" × 0.025" archwire were 50.18 Nmm, 54.52 µm, 32.47 µm and 19.11 µm respectively. Similarly for 0.019" × 0.025" archwire in 0.022" slot and 0.021" × 0.025" archwire in 0.022" slot they were 38.82 Nmm, 50.78 µm, 31.47 µm and 16.82 µm, and 60.22 Nmm, 65.22 µm, 36.44 µm and 22.68 µm respectively. ConclusionsThe slot deformation was present in both 0.018" and 0.022" brackets which increased as the angle of twist increased. The TSD were higher than the MSD and BSD in all the bracket-archwire combinations. We conclude that there is only elastic deformation of bracket slots upto 30o angle of twist and clinicians could maintain within this torque limits to avoid plastic deformation leading to improper teeth position.

Comparison of the Perception of Pain during Fixed Orthodontic Treatment with Metal and Ceramic Brackets.

Introduction:Pain is experienced by patients during various fixed orthodontic procedures such as placement of separators, insertion of arch wire and its activations, orthopedic appliances such as headgear, and debonding of the appliance. This study was formulated with the background that the level of pain sensation differs between conventional metal and ceramic brackets, arch wire being the same.Materials and Methods:The sample comprised 40 patients. The patients were separated into two groups: Group A (metal brackets) and Group B (ceramic brackets). In Group A, the brackets were bonded with 0.022” conventional stainless steel brackets (Unitek Gemini, 3M, Monrovia, California). In Group B, the brackets were bonded with ceramic brackets (Unitek Gemini Clear Brackets, 3M, Monrovia, California). The bonding of the brackets was carried out according to the conventional etching, priming, and curing technique. A 0.016” NiTi (nickel titanium) arch wire was used as the first arch wire. The intensity of pain was documented in a figure containing two 100-mm visual analog scales (VASs).Results:The level of pain reduced in intensity in due course. During 1 month, VAS scores increased at the end of day 1 (24 h) for the metal and ceramic group. The pain then decreased for up to 5 days. The average pain intensity reached 4.44 in the ceramic group, whereas it was 2.7 in the metal group for the upper anterior region. It decreased up to 1 in the ceramic and 0.22 in the metal group.Conclusion:Patients bonded with ceramic brackets experienced a higher and more severe pain of longer duration than individuals treated with conventional brackets.

Evaluations of Saliva for Nickel release from Conventional Stainless Steel and Nickel free Orthodontic brackets- An Atomic Absorption Spectrophotometric (AAS) study

Introduction: Nickel, which is a potent allergen, is used as a key metallurgical ingredient for manufacturing orthodontic brackets. The study aims at extracting nickel levels in patient’s saliva at different time interval. Methods: A total of twenty patients, ten bonded with conventional 3M Stainless steel brackets (group A) and another ten with nickel free brackets(group B). Group B was further divided into two groups of five each, based on different manufacturing companies viz Classic orthodontic and d-tech orthodontics. Three samples of stimulated saliva were collected from each patient at the following intervals: before placement of appliance, one hour after placement and a week after the appliance is being placed. The sample were then analysed with an atomic absorption spectrophotometer for amount of nickel release. Results: Study revealed that the nickel release in 3M stainless brackets in first hour of the bracket placement was very high compared to pre- treatment nickel level. Gradually the release was found to decrease when it was measured after one week. In the second group comprising nickel free brackets by Classic orthodontics the release of nickel gradually increased from the time the appliance was placed in the oral cavity over a period of one week. Third group having d- tech nickel free orthodontic brackets the release in nickel was found to be significantly on higher side after one hour of the appliance placement which eventually decreased over a period of one week. Conclusions: The final outcome of the present study revealed that manufacturing companies and extended time interval has a profound effect on nickel release from simulated fixed orthodontic appliance. Nickel free brackets used in the study though claim to be absolutely nickel free but some amount of nickel was found in them also. Keywords: Nickel, Atomic Absorption Spectrophotometer

Frictional force released during sliding mechanics in nonconventional elastomerics and self-ligation: An in vitro comparative study

Aim and Objectives:The aim of this study is to evaluate the frictional forces generated by five different orthodontic brackets when used in combination with stainless steel (SS), titanium molybdenum alloy (TMA), and nickel-titanium (NiTi) archwires in dry conditions at physiological temperature.Materials and Methods:Five different types of maxillary upper right side self-ligating brackets (SLBs) (Damon 3MX, Smart Clip and Carriere LX) and conventional SS brackets (Mini 2000, Optimum Series and Victory Series) with a slot size 0.022 inch were coupled with 0.016” NiTi and 0.019 × 0.025” SS/titanium molybdenum alloy (TMA) archwires. Tests were carried out for each group of the bracket-wire combination at physiological temperature and in the dry state. Frictional forces were measured by Instron universal testing machine.Results:SLB showed lower fictional values in comparison with elastic ligatures. Frictional force increased proportionally to the wire size; TMA and NiTi archwires presented higher frictional resistance than SS archwires.Conclusion:SS brackets tied with conventional ligatures produced high and low friction when ligated with SLBs with passive clip.

Comparison of the frictional characteristics of aesthetic orthodontic brackets measured using a modified in vitro technique.

ObjectiveThe coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined.MethodsFour types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a 0.017 × 0.025-in wire in the 0.018-in slots and a 0.019 × 0.025-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (α = 0.05) were also used for statistical analyses.ResultsThere were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (µ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (µ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (µ = 0.85).ConclusionsBrackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.

Comparison of friction among low-friction ligation, conventional ligation and self ligation with conventional stainless steel and esthetic brackets – an in vitro study

BackgroundAmong the numerous factors affecting friction between the bracket-archwire interface, the method of ligation is one of the most important. A number of ways have been proposed to reduce this friction, including self-ligating brackets and more recently Slide™ (Leone SpA, Firenze, Italy) low-friction ligatures. This study aims to compare the frictional forces generated by three different ligation methods; conventional ligation, self ligation and Slide low-friction ligation, using metallic and ceramic brackets. Materials and methodsThree models with 10 aligned brackets (standard, self-ligating and ceramic) were used with conventional and low-friction ligatures to study the frictional resistance generated with 0.016″ Nitinol (NiTi) and 0.019 × 0.025″ Stainless steel (SS) wires. ResultsConventional ligation produced the greatest friction regardless of wire or bracket combination used. With smaller round wires, the self-ligating system exhibited less friction than low-friction ligation and with higher dimension archwires it exhibited greater friction. Slide low-friction ligatures were able to reduce the friction of ceramic brackets in a similar way to stainless steel brackets. ConclusionSlide low-friction ligatures produced a reduction in friction with both metallic and ceramic brackets to a level comparable to that of self-ligating brackets.

Effect of visual method vs plaque disclosure in enhancing oral hygiene in adolescents and young adults: A single-blind randomized controlled trial

Enamel demineralization and gingival inflammation are the most prevalent consequences of biofilm formation in orthodontics. Our hypothesis was that educating patients about the severe consequences of biofilm accumulation could enhance their oral hygiene while wearing fixed appliances. This study was designed as a randomized controlled 4-arm parallel trial. A total of 148 participants in Chengdu, China, matching the eligibility criteria of 11 to 25 years of age, at least 20 natural teeth, and a treatment plan that included conventional stainless steel brackets, were randomly assigned to 4 intervention groups based on computer-generated random sequencing using simple randomization without blocking. In group A (n= 37), the subjects were shown images illustrating the severe consequences of biofilm formation, including enamel demineralization and gingival inflammation; subjects in group B (n= 40) were given biofilm disclosing tablets; those in group C (n= 38) received a combination of A and B; the subjects in group D (n= 33) served as the controls. The investigators were blinded to the allocations, and the researcher managing the random sequence did not participate in allocation or measurement. All groups received routine oral hygiene instructions. Plaque index and gingival index scores were recorded at each appointment during a 6-month follow-up. Eighteen participants were lost during follow-up, resulting in a total of 130 participants after the trial (group A, 35; group B, 32; group C, 34; group D, 29). No adverse events were recorded. Groups A and C exhibited a significantly lower plaque index scores (parameter-estimate [95% confidence interval]= -1.20 [-1.76 to -0.63] for group A, and -1.12 [-1.69 to -0.56] for group C) and gingival index scores (-0.13 [-0.21 to -0.04], and -0.19 [-0.28 to -0.10]), respectively, compared with group D (P<0.001 for all), whereas no significant difference was found between groups B and D, or between groups A and C (P>0.05). The adults had significantly lower plaque index (0.48 [0.13-0.84], P<0.001) and gingival index (0.06 [0.01-0.11], P= 0.018) scores than did the teenagers, and the female subjects had significantly higher gingival index (-0.06 [-0.11 to -0.01], P= 0.040) scores than did the male subjects. The use of images showing the severe consequences of biofilm accumulation enhanced the oral hygiene of patients treated with fixed appliances.

The effect of an acidic food-simulating environment on the shear bond strength of self-ligating brackets with different base designs.

Aim. This study aims to evaluate the effect of acidic food simulant and (acetic acid 3%) on the shear bond strength (SBS) and adhesive remnant index (ARI) scores of one conventional and three different self-ligating brackets with different base designs. Materials and Methods. Freshly extracted first maxillary premolars (n = 160) were embedded in resin blocks. A conventional stainless steel bracket, Equilibrium 2, and three types of self-ligating brackets, Speed, In-Ovation R, and Damon 3MX, were bonded to teeth and exposed to distilled water (groups 1, 3, 5, and 7) or acetic acid 3% (groups 2, 4, 6, 8) for 12 weeks. SBS and ARI were calculated and statistical analysis was performed with the analysis of variance (SBS) or χ 2 test (ARI) to compare values between the different groups. Results. Equilibrium 2 and In-Ovation R showed a significantly lower SBS in the acidic environment than in distilled water. Significant differences in ARI scores were found for Equilibrium 2 after immersion in an acidic environment, shifting from 0 in distilled water to 2 in an acidic environment. Conclusions. Equilibrium 2 and In-Ovation R brackets showed a significant decrease in SBS after a 12-week immersion in acetic acid 3%, although all groups showed clinically acceptable SBS. Equilibrium 2 showed significant differences in ARI scores when exposed to acetic acid 3%.

Residents' journal review

Residents' journal review

Comparison of Galvanic Corrosion Potential of Metal Injection Molded Brackets to that of Conventional Metal Brackets with Nickel-Titanium and Copper Nickel-Titanium Archwire Combinations

The aim of the study is to investigate the galvanic corrosion potential of metal injection molding (MIM) brackets to that of conventional brackets under similar in vitro conditions with nickel-titanium and copper nickel-titanium archwires. Twenty-five maxillary premolar MIM stainless steel brackets and 25 conventional stainless steel brackets and archwires, 0.16 inch, each 10 mm length, 25 nickeltitanium wires, 25 copper nickel-titanium wires were used. They were divided into four groups which had five samples each. Combination of MIM bracket with copper nickel-titanium wire, MIM bracket with nickel-titanium wire and conventional stainless steel brackets with copper nickel-titanium wire and conventional stainless steel brackets with nickel-titanium wires which later were suspended in 350 ml of 1 M lactic acid solution media. Galvanic corrosion potential of four groups were analyzed under similar in vitro conditions. Precorrosion and postcorrosion elemental composition of MIM and conventional stainless steel bracket by scanning electron microscope (SEM) with energy dispersive spectroscope (EDS) was done. MIM bracket showed decreased corrosion susceptibility than conventional bracket with copper nickeltitanium wire. Both MIM and conventional bracket showed similar corrosion resistance potential in association with nickel-titanium archwires. It seems that both brackets are more compatible with copper nickel-titanium archwires regarding the decrease in the consequences of galvanic reaction. The EDS analysis showed that the MIM brackets with copper nickel-titanium wires released less metal ions than conventional bracket with copper nickeltitanium wires. MIM brackets showed decreased corrosion susceptibility, copper nickel-titanium archwires are compatible with both the brackets than nickel-titanium archwires. Clinically MIM and conventional brackets behaved more or less similarly in terms of corrosion resistance. In order to decrease the corrosion potential of MIM brackets, more precise manufacturing technique should be improved to get a more smoother surface finish.

A comparative study of frictional resistance during simulated canine retraction on typodont model.

Objectives:Frictional resistance is an important counterforce to orthodontic tooth movement during sliding mechanics. This study was carried out to evaluate the effect of different bracket-archwire-ligation combinations on “resistance to sliding” during simulated canine retraction on typodont model.Materials and Methods:the frictional resistance was tested between three modern orthodontic brackets-stainless steel, ceramic, and ceramic with metal slot (0.022-inch), and seven different archwires (0.019 × 0.025-inch)-stainless steel, nickel-titanium, Teflon coated stainless steel, stainless steel with the reverse curve of spee (RCS), Teflon coated stainless steel with RCS, Teflon coated nickel-titanium and nickel-titanium with RCS ligated with stainless steel ligature wire and regular clear elastomeric modules. All tests were carried out in a dry state on an Instron universal testing machine (crosshead speed: 0.5 mm/min). 10 measurements were made from each bracket-archwire-ligature combinations.Results:The highest mean frictional resistance was found in ceramic brackets with nickel-titanium RCS archwire ligated with elastomeric modules while minimum frictional resistance was found in stainless steel brackets with Teflon coated stainless steel archwire ligated with stainless steel ligature. Metal slot ceramic brackets generated significantly lower frictional forces than ceramic brackets, but higher values than stainless steel brackets. Teflon coated archwires shows highly significant reduction of the frictional resistance than their corresponding uncoated archwires. Archwires with RCS had the higher frictional resistance than normal counterpart archwires.Conclusion:Ceramic brackets with metal slot and Teflon coated SS archwires seem to be a good alternative to conventional stainless steel brackets and archwires in space closure with sliding mechanics in patients with esthetic demands.

The comparison of frictional resistance in titanium, self-ligating stainless steel, and stainless steel brackets using stainless steel and TMA archwires: An in vitro study

Aim:The aim of the study was to compare the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and titanium molybdenum alloy (TMA) archwires.Materials and Methods:We compared the frictional resistance in 0.018 slot and 0.022 slot of the three brackets – titanium, self-ligating stainless steel, and conventional stainless steel – using stainless steel archwires and TMA archwires. An in vitro study of simulated canine retraction was undertaken to evaluate the difference in frictional resistance between titanium, self-ligating stainless steel, and stainless steel brackets, using stainless steel and TMA archwires.Results and Conclusion:We compared the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and TMA archwires, with the help of Instron Universal Testing Machine. One-way analysis of variance (ANOVA), Student's “t” test, and post hoc multiple range test at level of <0.05 showed statistically significant difference in the mean values of all groups. Results demonstrated that the titanium, self-ligating stainless steel, and stainless steel brackets of 0.018-inch and 0.022-inch slot had no significant variations in frictional résistance. The self-ligating bracket with TMA archwires showed relatively less frictional resistance compared with the other groups. The titanium bracket with TMA archwires showed relatively less frictional resistance compared with the stainless steel brackets.

Effects of self‐ligating brackets on the surfaces of stainless steel wires following clinical use: AFM investigation

In orthodontic treatment, the frictional force between the archwire and bracket reduces the effectiveness of orthodontic treatment. The frictional force is affected not only by the geometry of the self-ligating brackets but also by physical changes between the bracket slots and archwire surfaces during sliding movement. This study examined quantitatively the effect of self-ligating treatments on the surfaces of stainless steel (SS) archwires during tooth movement in vivo by atomic force microscopy. Orthodontic 0.019″ × 0.025″ SS archwires after clinical use with the first bicuspid-extraction treatment were employed using the Damon 3MX(®) SS self-ligating brackets, Clippy-C(®) ceramic self-ligating brackets, and Kosaka(®) SS brackets. Intact SS archwires were used as the control group. All SS archwires after clinical use showed severe scratches and significantly higher roughness caused by frictional interactions between the brackets and archwires (p < 0.0001 vs. control). The descending order of surface roughness was the SS archwires treated, with ceramic self-ligating brackets, with conventional SS brackets, and with SS self-ligating brackets (p < 0.001). These findings suggest that an orthodontic treatment with SS self-ligating brackets may require smaller orthodontic forces than that with ceramic self-ligating brackets or conventional SS brackets.

Effects of a diamond-like carbon coating on the frictional properties of orthodontic wires

To test the hypothesis that a diamond-like carbon coating does not affect the frictional properties of orthodontic wires. Two types of wires (nickel-titanium and stainless steel) were used, and diamond-like carbon (DLC) films were deposited on the wires. Three types of brackets, a conventional stainless steel bracket and two self-ligating brackets, were used for measuring static friction. DLC layers were observed by three-dimensional scanning electron microscopy (3D-SEM), and the surface roughness was measured. Hardness and elastic modulus were obtained by nanoindentation testing. Frictional forces and surface roughness were compared by the Kruskal-Wallis and Mann-Whitney U-tests. The hardness and elastic modulus of the wires were compared using Student's t-test. When angulation was increased, the DLC-coated wires showed significantly less frictional force than the as-received wires, except for some wire/bracket combinations. Thin DLC layers were observed on the wire surfaces by SEM. As-received and DLC-coated wires had similar surface morphologies, and the DLC-coating process did not affect the surface roughness. The hardness of the surface layer of the DLC-coated wires was much higher than for the as-received wires. The elastic modulus of the surface layer of the DLC-coated stainless steel wire was less than that of the as-received stainless steel wire, whereas similar values were found for the nickel-titanium wires. The hypothesis is rejected. A DLC-coating process does reduce the frictional force.