Titanium Molybdenum Alloy Archwires Research Articles

In Vitro Comparison to Evaluate Metal Ion Release: Nickel-Titanium vs. Titanium-Molybdenum Orthodontic Archwires.

Background When metals used in orthodontic materials are exposed to the oral environment, teeth, and gingivae over an extended period of time, they may gradually deteriorate. As a result, the patient is exposed to higher concentrations of metals and metal ions than what they would be exposed to through food and other sources. The goal of the current in vitro experiment was to evaluate and contrast the metal ion release from orthodontic archwires made of titanium-molybdenum alloy (TMA) and nickel-titanium (NiTi). Methods For 90 days, 20 orthodontic archwires in each group were immersed in 50 milliliters of simulated saliva using different containers. Atomic Absorption Spectrometry (AAS) (Shimadzu Corporation, Kyoto, Japan) was used to assess and compare metal ion emission. The unit of measurement is parts per million (PPM). Results The findings indicated that the discharge of nickel metal from the NiTi archwire (Group A) was much higher than that from the TMA archwire (Group B), with a statistical significance level of p < 0.001. It was discovered that Group B's release of titanium was statistically significantly (p < 0.05) higher than Group A's titanium release, which did not include the release of any other metals. Conclusion The study findings indicated that the amounts of metal ions released from the orthodontic archwires made of titanium molybdenum and nickel-titanium alloy were within safety limits.

Metal Release and Cytotoxicity of Different Orthodontic Bracket-Wire Combinations: An In Vitro Study.

To quantify and compare the metal ions released from different bracket-wire combinations and to assess their cytotoxicity. A total of 360 fabricated sectional fixed orthodontic appliances were divided into 6 groups. The first three groups consisted of stainless-steel brackets with stainless-steel, snickel-titanium (NiTi), and titanium-molybdenum alloy (TMA) archwires, and the other three groups were fabricated using ceramic brackets (polycrystalline alumina) with stainless-steel, NiTi, and TMA archwires. These appliances were immersed in artificial saliva (pH 6.5 ± 0.5, 37°C), for 1 week, 2 weeks, and 1 month. The nickel and chromium ions released in the artificial saliva were quantified using a flame atomic absorption spectrometer, and cytotoxicity assessment was performed using a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay on human cervical cancer cell line. The stainless-steel bracket groups displayed a significantly greater release of nickel and chromium ions compared to the ceramic bracket groups (P < 0.05). However, no significant differences were identified when comparing the three archwire types within the stainless-steel/ceramic bracket groups. At the end of 1 month, the % cell viability demonstrated by the appliances was in the decreasing order of stainless-steel-TMA > ceramic-stainless steel > stainless-steel-NiTi > ceramic-NiTi > stainless-steel-stainless steel > ceramic-TMA. Considerably greater release of nickel and chromium ions was observed from the appliances utilizing stainless-steel brackets compared to those employing ceramic brackets. However, no remarkable difference in the levels of nickel and chromium ions was observed when comparing the three archwires: stainless steel, NiTi, and TMA. In the cytotoxicity assessment, the ceramic-TMA combination displayed the highest level of cytotoxicity, while the stainless-steel-TMA combination displayed the least cytotoxicity.

Friction forces generated by aesthetic Gummetal® (Ti-Nb) orthodontic archwires: A comparative in vitro study

The aim of this in vitro study was to compare friction forces generated by the following archwires: rhodium-plated aesthetic Gummetal® (E-GM), Gummetal® (GM), stainless steel (SS) and titanium-molybdenum alloy (TMA), according to bracket-wire angulation and archwire cleanliness. One hundred and ninety-two samples of four orthodontic alloys (E-GM, GM, SS, and TMA) were prepared. The samples were divided into two groups: uncleaned and cleaned using 99% isopropanol in an ultrasonic bath, then subdivided into three subgroups according to bracket-wire angulation: 0°, 5° and 10°. Using a universal testing machine, the wires were pulled through SS maxillary right canine brackets to test static friction forces according to bracket-wire angulation and wire cleanliness. Representative specimens were evaluated to assess surface morphology and roughness. There were significant differences in static friction forces between archwires when analysed by bracket-wire angulation and cleanliness (P<0.001) except for the 0° uncleaned group. Overall, TMA archwires produced the highest friction while SS wires showed the lowest friction at 0° and 5°. E-GM wires showed comparable friction to SS at 0o (cleaned and uncleaned), but significantly higher friction than SS at 5o (uncleaned) and 10° (cleaned). GM wires had comparable friction to SS at 0° (cleaned and uncleaned), but significantly less friction at the 5° (cleaned) and 10° (cleaned and uncleaned). Compared to GM, E-GM had significantly higher friction at 5o and 10° (cleaned and uncleaned). Cleaning wires reduced surface roughness but increased overall friction. E-GM wires generate higher frictional resistance forces compared to GM and SS, especially at higher bracket-wire angulations and when cleaned. GM friction forces are comparable to SS and thus could be used for space closure with sliding mechanics. However, E-GM wires are not ideal for the same purpose.

Comparative in vitro analysis of the sliding resistance of a modern 3D-printed polymer bracket in combination with different archwire types.

ObjectivesTo analyse the sliding resistance of a modern 3D-printed polymer bracket combined with different archwire types and to compare the results with conventionally used polymeric, ceramic and metal brackets. It was of further interest which bracket-archwire combination could be best qualified for clinical use.Materials and methodsThe sliding behaviour was tested using an orthodontic measurement and simulation system (OMSS) for the use of two bracket types of the polymer, ceramic and metal group in combination with a 0.016 inch × 0.022 inch and 0.017 inch × 0.025 inch archwire of nickel-titanium (NiTi), titanium-molybdenum alloy (TMA) and stainless steel. Six bracket types were combined with six different archwire types and compared to each other.ResultsThe sliding resistance showed significant differences between various the bracket-archwire complexes. The combination of 3D-printed polymer brackets with both steel archwire cross-sections showed the least values of sliding resistance (average 23–29%), while the combination of ceramic brackets with TMA archwires presented the highest (average 47%).ConclusionsThe present study could show that modern 3D-printed bracket materials can have similar or even better mechanical properties than conventional ones regarding sliding resistance. Although the combination of bracket and archwire material is decisive for low sliding resistance values, the selection of the bracket material seems to have a greater influence than the selection of the archwire material or its cross section.Clinical relevanceIt might be possible in future to combine aesthetic and biomechanical requirements for aesthetic brackets by using 3D-printing technology.

Comparative finite element analysis of bracket deformation in tie wings and slot region during simulated torque

Torque in orthodontics is the activation of the archwire for the third-order movement of teeth. During this force transfer mechanism from the twisted archwire, the bracket is prone to deformation. This study aimed to compare the deformation in tie wings and the slot region of the bracket during torque using finite element analysis. Three-dimensionally modeled 0.017×0.025-in and 0.019×0.025-in stainless steel (SS) and titanium molybdenum alloy archwires were assembled in 0.018-in and 0.022-in solid modeled SS edgewise brackets, respectively. The finite element model of the bracket-archwire combinations was developed with contact boundary conditions. The deformation between tie wings and the slot was analyzed for various angles of twist. For SS archwires at 30° angle of twist, the tie wings deformation in 0.018-in and 0.022-in brackets were 48.67μm and 34.87μm, respectively. The slot deformations of 0.018-in and 0.022-in brackets were 66.33μm and 45.69μm, respectively. Similarly, the amount of deformation in the bracket-titanium molybdenum alloy archwire combinations were also presented. The slot deformation was more than the tie wings deformation as the slot walls bear the immediate torque force. Thus, orthodontic researchers should know that the torque-relevant bracket deformation should ideally be evaluated in the slot region rather than the tie wings.

Comparison of frictional resistance between four types of brackets in combination with stainless steel and beta-titanium archwires

Objectives: The objective of the study was to evaluate and compare the frictional resistance generated by four different types of brackets in combination with stainless steel (SS) and titanium molybdenum alloy (TMA) archwires. Materials and Methods: Maxillary premolar brackets were used in this study. These brackets were divided into eight groups comprising seven samples each. Of the eight groups, four groups were combined with SS and four groups were combined with TMA archwires. The testing was done in the presence of human saliva. The static frictional resistance was calculated for each group. One-way ANOVA and post hoc Tukey tests were done to compare the friction generated by each group. Results: There was a statistically significant difference between the friction generated by the monocrystalline brackets and the other bracket groups (P &lt; 0.001). There was no statistically significant difference in static friction generated between self-ligating and conventionally ligated brackets. There was a statistically significant difference between the frictional resistance produced by SS and TMA wires (P = 0.02) with regard to monocrystalline ceramic brackets only. Conclusion: Monocrystalline ceramic brackets (Radiance) were found to generate the highest frictional resistance during sliding mechanics when compared to other brackets in combination with both SS and TMA wires. Self-ligating brackets did not show a statistically significant reduction in friction when compared to conventional ligation. There was a statistically significant difference between SS and TMA wires when used with monocrystalline brackets.

Comparison of force loss during sliding of low friction and conventional TMA orthodontic archwires : An invitro study.

ObjectiveThe goal was to measure and compare the amount of force loss during tooth movement guided by archwires, including a newly introduced low-friction titanium molybdenum alloy (TMA), conventional TMA, and stainless steel archwires.MethodsThe force loss was measured using a specialized biomechanical set-up, the orthodontic measurement and simulation system (OMSS). A total of 30 specimen were used (10 low-friction TMA (TMA-Low), 10 conventional TMA (TMA-C), and 10 stainless steel (SS) archwires, each having a dimension of 0.016 × 0.022 inches). The conventional and low friction TMA archwires served as test groups, while the SS archwires served as the control group.ResultsThe mean values of force loss between the three types of wires (TMA‑C, TMA-Low, and SS) were significantly different (p < 0.0001). The highest mean force loss during sliding movement was found in the conventional TMA group (72.1%), followed by low friction TMA (48.8%) and stainless steel wires (33.7%) in a descending order.ConclusionThe friction property of the low friction TMA archwire was superior to the conventional TMA archwire but was still inferior to the stainless steel archwire.

Research paper: The three-dimensional mechanical response of orthodontic archwires and brackets in vitro during simulated orthodontic torque

Orthodontic archwire rotation around its long axis, known as third-order torque, is utilised to correct tooth rotational misalignments moving the tooth root closer to or away from the cheek through engagement with an orthodontic bracket. Studying the behaviour of archwire and brackets during an applied rotation can aid in better understanding and appreciating the mechanics of third-order torque, potentially allowing for more effective orthodontic treatment protocols. Mechanically characterising archwire behaviour during third-order torque application is a complex task due to their physical scale and geometries. An advanced measurement technique was needed to address these constraints. A three-dimensional (3D) non-contact optical method using a digital image correlation (DIC) system was developed. An orthodontic torque simulator (OTS) was used to apply and measure third-order torque with 0.483 × 0.635 mm (0.019″ x 0.025″) rectangular archwires in tandem with a 3D DIC system, whereby surface deformations and strains could be computed using correlation algorithms. The 3D DIC system was implemented to enable third-order torque experimentation with the OTS while imaging the archwire and bracket surfaces. The 3D DIC system's ability to measure 3D archwire deformations and strains was verified using a finite element model, where comparisons between 3D DIC measurements and calculated results from the model were made to ensure the measurement capabilities of 3D DIC in the context of third-order torque. The 3D DIC system was then used to compare archwire behaviour between stainless steel (SS) and titanium molybdenum alloy (TMA) archwires to study potential clinical differences in archwire behaviour, in which the archwires were rotated with a custom SS rigid dowel (RD) as well as commercial Damon Q orthodontic brackets. The quantification of third-order torque and archwire deformations and strains led to the conclusion that SS archwires led to larger torque magnitudes compared to TMA archwires. The RD resulted in larger archwire strains compared to Damon Q brackets. The 3D DIC system provides a non-contact measurement technique that can further be used with third-order torque experimentation with the OTS.

Tensile strength differences between nickel-titanium and titanium molybdenum alloy orthodontic archwire after immersion in detergent toothpaste

Background: Titanium-based alloys, such as nickel-titanium (NiTi) and titanium molybdenum alloy (TMA), have gained immense popularity in the last decades. Some toothpaste ingredients can negatively affect orthodontic procedures. Objective: The objective of this study was to examine the differences in tensile strength between NiTi and TMA orthodontic wires after immersion in detergent toothpaste. Methods: Six treatment groups were established, with NiTi and TMA wires immersed in 25 g detergent toothpaste for 4, 8, and 12 h. Tensile strength measurements were carried out using a Tensilon RTF-1350 universal testing machine. Results: The P values of the NiTi and TMA wires were as follows: 0.000 after 4 h, 0.000 after 8 h, and 0.002 after 12 h. These results showed that there were significant differences between the tensile strength of NiTi and TMA orthodontic wires after immersion in detergent toothpaste for increasing periods of time. Conclusion: The tensile strength of NiTi wire was greater than the tensile strength of TMA archwire. However, detergent toothpaste did not have a significant effect on change in tensile strength of NiTi and TMA wire.

In Vitro Comparative Evaluation of Frictional Resistance of Connecticut New Arch Wires, Stainless Steel and Titanium Molybdenum Alloy Archwires Against Different Brackets.

Background and objectivesFriction between the bracket and archwire during sliding mechanics is of great concern in orthodontics, as it reduces the effectiveness of the orthodontic appliance and slows down tooth movement. The aim of this study was to evaluate frictional resistance of stainless steel (SS), titanium molybdenum alloy (TMA), and Connecticut new arch (CNA) wires against SS and ceramic brackets. The surface textures of the brackets and wires were also evaluated by scanning electron microscopy (SEM) before and after testing.MethodA total of 180 premolar brackets of SS (ORMCO Corp., Orange, CA) and 180 ceramic (3M Unitek, Maplewood, MN) with a 0.022-inch slot and 180 SS, TMA, and CNA wires of 0.017 x 0.025 inches and 0.019 x 0.025 inches were tested. The SS brackets and ceramic brackets were bonded onto the SS bar with cyanoacrylate adhesive with the help of a jig. The wire assembly was vertically mounted and clamped to the jaws of the universal testing machine with 10 N load cell, and friction was measured along with other readings. The surface roughness of brackets and wires were examined using SEM in 200 X magnification before and after testing.ResultsTMA wire showed the greatest frictional force compared to SS and CNA wire. The frictional force was greater in the 0.019 x 0.025-inch wire compared to the 0.017 x 0.025-inch wires. The highest frictional force was noted in the SS bracket and 0.019 x 0.02-inch TMA wire combination. A statistically significant difference was not seen between the SS bracket and 0.019 x 0.025-inch SS wire and the 0.019 x 0.025-inch CNA wire combinations.SEM showed that the TMA archwire had the roughest surface area compared to SS and CNA wires, and the ceramic bracket had more surface roughness than the SS bracket.ConclusionCNA wire demonstrated frictional resistance similar to the SS wire. CNA wire can be used instead of TMA wire because of its better range of action, high spring back, and less frictional resistance for space closure in sliding mechanics.

Comparison of the microbial flora from different orthodontic archwires using a cultivation method and PCR: A prospective study.

The aim of this study was to evaluate the effects of superelastic nickel-titanium (SE NiTi), copper-nickel-titanium (CuNiTi) and titanium-molybdenum alloy (TMA) archwires with different surface properties on dental plaque retention and microbial colonization. Totally 25 individuals, consisting of 16 girls and nine boys with mean age of 15.69±1.70, were included in this study. The effects of the SE NiTi, CuNiTi and TMA archwires with different surface properties on the amount of Streptoccocus sp and Lactobacillus sp were investigated with three different parameters including clinical periodontal indexes, microbial swab and archwire samples. Phenotypic isolation was performed from microbial swab and archwire samples using culture method; genotypic isolations were performed by the polymerase chain reaction method. There was no statistically significant difference between SE NiTi, CuNiTi and TMA archwires in terms of periodontal parameters (P>.05). When microbial swabs and archwires samples from different archwire groups were evaluated by culture method, no statistically significant difference was found between the groups (P>.05). A statistically significant difference was found between the amount of Lactobacillus sp in the swab samples of the CuNiTi archwire after the purification period (P=.023). Smutans were found to be more quantity than other bacterial types in all archwires. The amount of microbial involvement was found to be lower in CuNiTi archwires than in the post-purification period. This may be due to the antimicrobial effect of copper.

Evaluation and comparison of surface characteristics of commercially available TMA wires using scanning electron microscopy and optical profilometer.

The aim of this study was to evaluate and compare the surface characteristics of colored titanium molybdenum alloy archwires (purple-coated TMA and honey dew-coated TMA) and the regular titanium molybdenum alloy archwires. The experiment comprised three groups, Group I - regular TMA archwires, Group II - purple-coated TMA archwires, Group III - honey dew-coated TMA wires involving 21 samples each. The surface characteristics were assessed using scanning electron microscopy and optical profilometer. The results were statistically analyzed using analysis of variance wherein Group I regular TMA wires exhibited a root mean square value of 148.071 nm and a standard deviation of 9.0027 nm followed by group II (purple-coated TMA wires) which showed a root mean square value of 84.095 nm with a standard deviation of 2.6005 nm, while group III (honey dew-coated TMA wires) was found to have a root mean square value of 71.681 nm with a standard deviation of 1.4645 nm on subjecting to optical profilometry. The surface roughness is higher for regular TMA wire exhibiting superior characteristic of color-coated TMA wires, especially honey dew-coated TMA wires over the regular and purple-coated TMA wires. This property of the archwires details regarding its application in both sliding and frictionless mechanics in retraction phase of fixed orthodontic treatment.

Evaluation of kinetic friction between regular and colored titanium molybdenum alloy archwires.

The aim of this study was to evaluate the kinetic frictional properties of colored titanium molybdenum alloy (TMA) archwires (purple-coated TMA and honey dew-coated TMA) and the regular TMA archwires. The experiment comprised of three groups, Group I - Regular TMA archwires, Group II - Purple-coated TMA archwires, Group III - Honey dew-coated TMA wires involving 21 samples each that were evaluated for their frictional properties using Instron Universal Testing Machine. The results were subjected to statistical analysis using analysis of variance wherein Group I Regular TMA wires revealed mean kinetic frictional value of 8.236 N and a standard deviation of 0.4038 N, while Group II (purple-coated TMA wires) showed a mean value of 5.297 N, standard deviation of 0.3128 N and Group III (honey dew-coated TMA wires) showed a mean value of 4.206 N and a standard deviation of 0.5353 N. The kinetic frictional values are higher for regular TMA wire exhibiting superior characteristic of color-coated TMA. Wires exhibiting superior characteristics are color-coated TMA wires, especially honey dew-coated TMA wires over the regular and purple-coated TMA wires. These superior properties of newly introduced wires can be considered for its application in both details friction and frictionless mechanics in retraction phase of fixed orthodontic treatment.

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.

Corrosion resistance of stainless steel, nickel-titanium, titanium molybdenum alloy, and ion-implanted titanium molybdenum alloy archwires in acidic fluoride-containing artificial saliva: An in vitro study.

Objective:(1) To evaluate the corrosion resistance of four different orthodontic archwires and to determine the effect of 0.5% NaF (simulating high fluoride-containing toothpaste of about 2250 ppm) on corrosion resistance of these archwires. (2) To assess whether surface roughness (Ra) is the primary factor influencing the corrosion resistance of these archwires.Materials and Methods:Four different archwires (stainless steel [SS], nickel-titanium [NiTi], titanium molybdenum alloy [TMA], and ion-implanted TMA) were considered for this study. Surface characteristics were analyzed using scanning electron microscopy, atomic force microscopy (AFM), and energy dispersive spectroscopy. Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance of four different archwires in artificial saliva with NaF concentrations of 0% and 0.5%. Statistical analysis was performed by one-way analysis of variance.Results:The potentiostatic study reveals that the corrosion resistance of low-friction TMA (L-TMA) > TMA > NiTi > SS. AFM analysis showed the surface Ra of TMA > NiTi > L-TMA > SS. This indicates that the chemical composition of the wire is the primary influential factor to have high corrosion resistance and surface Ra is only secondary. The corrosion resistance of all wires had reduced significantly in 0.5% acidic fluoride-containing artificial saliva due to formation of fluoride complex compound.Conclusion:The presence of 0.5% NaF in artificial saliva was detrimental to the corrosion resistance of the orthodontic archwires. Therefore, complete removal of residual high-fluorinated toothpastes from the crevice between archwire and bracket during tooth brushing is mandatory.

Finishing effectiveness of different archwires using SmartClip™ self-ligating brackets: A clinical study

The aim of this clinical prospective trial was to evaluate finishing effectiveness of stainless steel (SS) archwires versus titanium molybdenum alloy (TMA) archwires using SmartClip™ self-ligating brackets. Thirty-two patients were divided in two groups: a group of 21 (G1-SS) and a group of 12 (G2-TMA). The protocol consisted of two different finishing archwires coupled with self-ligating brackets: .019 × .025" SS archwires for G1-SS and .019 × .025" TMA archwires for G2-TMA. Lateral cephalometric radiographs obtained at the beginning (T1) and end (T2) of treatment were used to assess the changes in incisor inclination, and measurements of irregularity index (LII), interdental widths, arch length (AL) and arch depth (AD) were made on dental casts to investigate changes associated with crowding correction. No significant differences from T1 to T2 were found for incisors proclination and AL changes. Statistically significant differences were found for LII (higher decrease in G1-SS), maxillary AD (higher increase in G1-SS) and three interdental maxillary widths (higher in G1-SS). The statistically significant differences found were few and clinically negligible. Self-ligating brackets system coupled with .019 × .025" archwires showed good finishing effectiveness, but no clinically significant differences were found between SS and TMA.

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.

An in vitro comparison of the frictional forces between archwires and self-ligating brackets of passive and active types

The aim of this study was to compare the static and kinetic frictional forces generated by various contemporary designs of self-ligating brackets (SLBs) and different wire alloys. In total, six different brackets (four passive type SLB, one active SLB, and one conventional bracket) were investigated using stainless steel, nickel-titanium, and titanium-molybdenum alloy archwires of several sizes. The friction forces were measured by sliding on a bracket-wire combination system in an EZ instron testing machine. A scanning electron microscope (SEM) was used to examine the wear effects of the wall surfaces of bracket slots. Energy-dispersive spectroscopy (EDS) was used to identify the elemental compositions of the bracket surfaces. The data were collected and statistically analysed using analysis of variance. The results of static and kinetic frictional forces were lower in passive type SLBs (P < 0.05), except in the Smart Clip bracket. The wire materials or wire dimensions in the present study showed similar friction forces with no statistical differences (P > 0.05). The wearing effects were not obviously found in bracket slots under SEM observation. Only conventional brackets and mini-Clippy SLB revealed nickel ions via EDS analysis. This study shows that passive SLBs are associated with lower static or kinetic friction forces than those of active SLBs or conventional brackets. Wear on the bracket slots was not observed in the present study.

The monitoring of gingival crevicular fluid volume during orthodontic treatment: a longitudinal randomized split-mouth study

This randomized split-mouth study was aimed at evaluating whether an orthodontic appliance per se or orthodontic tooth movement can induce detectable changes in gingival crevicular fluid (GCF) volume, and thus whether GCF volume is a predictable biomarker for tissue remodelling incident to orthodontic tooth movement. Sixteen healthy orthodontic patients (7 females and 9 males; mean age, 17.7 years; range, 13-27 years) with the need for extraction of the first upper premolars were enrolled. One randomly chosen maxillary canine was subjected to a distalizing force by a 0.017 × 0.025 inch titanium-molybdenum alloy archwire and considered as the test tooth (TT). The contralateral canine, which was not subjected to any force but was included in an orthodontic appliance, was used as a control (CT). GCF sampling was performed at both mesial and distal sites of the CTs and TTs at baseline, immediately before applying the orthodontic appliance, and after 1 hour, 24 hours, and 7, 14, and 21 days. A Periotron was used to measure the GCF volume. A modest but significant increase in the GCF volume over time was seen in both the CTs (mesial sites) and the TTs (both mesial and distal sites) with no differences between the experimental teeth. Subclinical tissue inflammation consequent to the placement of the orthodontic appliance might be responsible for these GCF volume changes. The GCF volume does not appear to be a reliable biomarker for tissue remodelling during orthodontic treatment.

Static frictional force and surface roughness of various bracket and wire combinations

During sliding mechanics, frictional resistance is an important counterforce to orthodontic tooth movement, which must be controlled to allow application of light, continuous forces. We investigated the static frictional resistance between 3 modern orthodontic brackets-ceramic with gold-palladium slot, ceramic, and stainless steel-and 4 archwires (0.019 × 0.025-in)-stainless steel, nickel-titanium, titanium-molybdenum alloy (TMA), and low-friction colored TMA. All tests were carried out in a dry state on a universal testing machine. Surface topography of bracket slots and archwires was studied by using a scanning electron microscope and quantified by using a surface roughness testing machine (profilometer). In the scanning electron microscope measurements, the smoothest surface was the ceramic gold-palladium bracket and stainless steel wire. The profilometer quantified the surface roughness, which also was lowest for the ceramic gold-palladium bracket and stainless steel wire. The ceramic bracket with the gold-palladium slot showed the least frictional values in all combinations and could be a promising alternative to solve the problem of friction. Frictional values for colored TMA were comparable with stainless steel wires and might be a good alternative during space closure in sliding mechanics. Ceramic with gold-palladium slot bracket and colored TMA archwire seem to be a good alternative to stainless steel in space closure with sliding mechanics.