Second molar intrusion: Continuous arch or loop mechanics?

INTRODUCTION: Our aim was to compare the load systems produced by rectangular loops and continuous arch mechanics on intrusion of a maxillary second molar. METHODS: An orthodontic appliance was passively bonded from second molar to second molar on a patient's model fixed to an orthodontic force tester. The second molars were extruded by 3 mm, and 2 mechanics systems were compared: beta-titanium rectangular loops and super-elastic nickel-titanium continuous arch. Vertical (Fz) and mesial (Fy) forces, and tipping moments around the buccal axis (Mx) at the tubes were collected at every 0.5 mm of deactivation. Repeated measures analysis of variance was used to detect differences between mechanics. The net Mx was also estimated at the center of resistance of each molar. RESULTS: Significant differences were found between the mechanics at the tubes, except for the Mx in the first molar, and more importantly, at the centers of resistance of the molars: Fz forces were greater in the continuous arch than in the rectangular loops, which, on the other hand, produced lower Fy forces than the continuous arch. In the second molar, net Mx was low initially and changed with deactivation. In the continuous arch, net Mx decreased from -3.6 N.mm of mesial crown tipping to clinically insignificant levels after 2 mm of deactivation. In the first molar, net Mx was lower on the rectangular loop than on the continuous arch during the first 2 mm of deactivation and became similar in the last millimeter of deactivation. Additionally, the net Mx decreased with deactivation with both mechanics. CONCLUSIONS: Both mechanics can intrude the second molars. Although the rectangular loop produced less tipping in large deflections, the continuous arch was a better approach when less intrusion was required.

Continuous arch and rectangular loops for the correction of consistent and inconsistent load systems in extruded and tipped maxillary second molars.

INTRODUCTION: The aim of this research was to compare the load systems produced by rectangular loops and continuous arches for the correction of extruded second molars with a mesial inclination (inconsistent system) and a distal inclination (consistent system). METHODS: The maxillary first molar of an acrylic model of a patient, with passive brackets and tubes bonded, was connected to a 3-dimensional load cell of an orthodontic force tester, and the second molar was replaced by its respective tube bonded to a second load cell. The second molar tube was moved 2.5 mm occlusally and tipped 20° mesially and distally, creating an inconsistent force system and a consistent force system. For each situation, ten 0.017 × 0.025-in beta-titanium, 8 × 10-mm rectangular loops were compared with 10 0.014-in nickel-titanium continuous arches. The vertical forces-F(z)-and tipping moments-M(x)-were compared using 4 t tests, at 5%. RESULTS: In the inconsistent group, the rectangular loop produced a larger M(x) in both molars: 2.11 N.mm in the second molar compared with the -0.15 N.mm of the continuous arches. On the first molar, the rectangular loops produced -5.58 N.mm against -2.08 N.mm produced by the continuous arches. The F(z) values produced at the second molar with each system were similar, whereas on the first molar they were different; the rectangular loops produced 0.41N, and continuous arches produced 0.53N. In the consistent group, the rectangular loops produced smaller M(x) values at the second molar (-3.06 N.mm) than did the continuous arch (-4.25 N.mm) (P = 0.01), as well as a smaller F(z) value (-0.52 vs -0.92 N, respectively). At the first molar, the rectangular loops produced smaller M(x) values (-2.32 N.mm) than did the continuous arch (-4.18 N.mm), as well as a smaller F(z) value (0.59 vs 1.10 N). CONCLUSIONS: In the inconsistent group, only the rectangular loop produced a system of force that could correct the second molar. In the consistent system, both group mechanics produced a system of force compatible with the correction of the second molar, but the continuous wire produced larger moments. Both groups showed a tendency for mesial crown tipping of the first molar.

Assessing adhesive remnant removal and enamel damage with ultraviolet light: An in-vitro study.

INTRODUCTION: Our objective was to assess the amounts of adhesive remnant and enamel damage when removing composite under conventional lighting and ultraviolet (UV) light. METHODS: Thirty-eight premolars were divided into 2 groups according to the lighting used for adhesive removal. A multifluted tungsten-carbide bur at low speed was used for this process in both groups. The UV group received conventional lighting associated with UV light, and the conventional group received conventional lighting only. The amounts of adhesive remnant were calculated using images of the teeth taken under UV light with software. Scanning electron microscopy images of epoxy adhesive replicas of the teeth made before bonding and after adhesive removal were graded according to the enamel damage index (EDI), and the difference between the final and initial EDI scores was used for assessment of the enamel damage. To detect differences between the groups, the Mann-Whitney test was used to analyze the data from the adhesive remnant index and the EDI. RESULTS: The conventional group had more adhesive left on the enamel (P <0.001) than did the UV group. There was no difference between groups for the EDI (P = 0.729). CONCLUSIONS: UV lighting allows significantly more adhesive removal without increasing the damage caused to the enamel.

Effect of clinical use of nickel-titanium springs.

INTRODUCTION: Our objectives were to determine whether there are changes on the load deflection rate (L/DP) and the average force (FP) of the superelastic pseudoplateau, and whether permanent deformation is changed in nickel-titanium closed-coil springs (CCSs) after 6 months of clinical use. METHODS: Twenty-two nickel-titanium CCSs (Sentalloy 100 g; Dentsply GAC, York, Pa) were subjected to tensile mechanical testing at 37°C on activations varying from 3.2 to 16.0 mm before and after 6 months of clinical use. A regression line was fitted over the most horizontal area of the unloading part of the stress-strain graph of every CCS, and its slope was used as L/DP. The FP was determined by the midpoint of the longest segment of the curve that could be fit within the regression line with a R(2) of at least 0.999, and permanent deformation was determined graphically by obtaining the strain value when the measured stress reached zero. The data were analyzed by 3 analyses of variance at 2 levels, with 5% of significance. RESULTS: Time and activation significantly influenced the variables tested (P < 0.001). Time increased the L/DP and permanent deformation but decreased the FP. Activation decreased L/DP, FP, and permanent deformation. Significant interactions between time and activation were detected for FP (P = 0.013) and deformation (P < 0.001). CONCLUSIONS: After 6 months of active clinical use, the analyzed springs had a significant but small increase in their L/DP; FP dropped up to 88%, and the CCSs deformed up to 1.26 mm.

Orthodontic Treatment in Adult Patient with Reduced Periodontium: A Case Report.

Patients presenting reduced periodontium represent a major concern for orthodontists. The purpose of this article is to present the clinical case of an adult patient who presented sequel of periodontal disease (diastemas) compromising her dental aesthetics. She was subjected to an orthodontic treatment with the application of light forces distant from the teeth with reduced periodontium. A periodontal support therapy was successfully implemented. The final stage of the treatment indicated satisfactory occlusal and periodontal characteristics.

Time reduction of light curing: Influence on conversion degree and microhardness of orthodontic composites.

INTRODUCTION: The aim of this study was to assess the influence of curing time and power on the degree of conversion and surface microhardness of 3 orthodontic composites. METHODS: One hundred eighty discs, 6 mm in diameter, were divided into 3 groups of 60 samples according to the composite used-Transbond XT (3M Unitek, Monrovia, Calif), Opal Bond MV (Ultradent, South Jordan, Utah), and Transbond Plus Color Change (3M Unitek)- and each group was further divided into 3 subgroups (n = 20). Five samples were used to measure conversion, and 15 were used to measure microhardness. A light-emitting diode curing unit with multiwavelength emission of broad light was used for curing at 3 power levels (530, 760, and 1520 mW) and 3 times (8.5, 6, and 3 seconds), always totaling 4.56 joules. Five specimens from each subgroup were ground and mixed with potassium bromide to produce 8-mm tablets to be compared with 5 others made similarly with the respective noncured composite. These were placed into a spectrometer, and software was used for analysis. A microhardness tester was used to take Knoop hardness (KHN) measurements in 15 discs of each subgroup. The data were analyzed with 2 analysis of variance tests at 2 levels. RESULTS: Differences were found in the conversion degree of the composites cured at different times and powers (P <0.01). The composites showed similar degrees of conversion when light cured at 8.5 seconds (80.7%) and 6 seconds (79.0%), but not at 3 seconds (75.0%). The conversion degrees of the composites were different, with group 3 (87.2%) higher than group 2 (83.5%), which was higher than group 1 (64.0%). Differences in microhardness were also found (P <0.01), with lower microhardness at 8.5 seconds (35.2 KHN), but no difference was observed between 6 seconds (41.6 KHN) and 3 seconds (42.8 KHN). Group 3 had the highest surface microhardness (35.9 KHN) compared with group 2 (33.7 KHN) and group 1 (30.0 KHN). CONCLUSIONS: Curing time can be reduced up to 6 seconds by increasing the power, with a slight decrease in the degree of conversion at 3 seconds; the decrease has a positive effect on the surface microhardness.

Molecular detection of in-vivo microbial contamination of metallic orthodontic brackets by checkerboard DNA-DNA hybridization.

INTRODUCTION: Knowing the microbiota that colonizes orthodontic appliances is important for planning strategies and implementing specific preventive measures during treatment. The purpose of this clinical trial was to evaluate in vivo the contamination of metallic orthodontic brackets with 40 DNA probes for different bacterial species by using the checkerboard DNA-DNA hybridization (CDDH) technique. METHODS: Eighteen patients, 11 to 29 years of age having fixed orthodontic treatment, were enrolled in the study. Each subject had 2 new metallic brackets bonded to different premolars in a randomized manner. After 30 days, the brackets were removed and processed for analysis by CDDH. Data on bacterial contamination were analyzed descriptively and with the Kruskal-Wallis and Dunn post tests (α = 0.05). Forty microbial species (cariogenic microorganisms, bacteria of the purple, yellow, green, orange complexes, "red complex +Treponema socranskii," and the cluster of Actinomyces) were assessed. RESULTS: Most bacterial species were present in all subjects, except for Streptococcus constellatus, Campylobacter rectus, Tannerella forsythia, T socranskii, and Lactobacillus acidophillus (94.4%), Propionibacterium acnes I and Eubacterium nodatum (88.9%), and Treponema denticola (77.8%). Among the cariogenic microorganisms, Streptococcus mutans and Streptococcus sobrinus were found in larger numbers than L acidophillus and Lactobacillus casei (P <0.001). The periodontal pathogens of the orange complex were detected in larger numbers than those of the "red complex +T socranskii" (P <0.0001). Among the bacteria not associated with specific pathologies, Veillonella parvula (purple complex) was the most frequently detected strain (P <0.0001). The numbers of yellow and green complex bacteria and the cluster of Actinomyces were similar (P >0.05). CONCLUSIONS: Metallic brackets in use for 1 month were multi-colonized by several bacterial species, including cariogenic microorganisms and periodontal pathogens, reinforcing the need for meticulous oral hygiene and additional preventive measures to maintain oral health in orthodontic patients.

Force system evaluation of symmetrical beta-titanium T-loop springs preactivated by curvature and concentrated bends.

INTRODUCTION: The objective of this research was to compare the effect of preactivation on the force system of beta-titanium T-loop springs (TLSs). METHODS: Twenty TLSs with dimensions of 6 × 10 mm, of 0.017 × 0.025-in beta-titanium alloy, were randomly divided into 2 groups according to their preactivation. By using a moment transducer coupled to a digital extensometer indicator adapted to a testing machine, the amounts of horizontal force and moment produced were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation in an interbracket distance of 23 mm. The moment-to-force ratio, the "neutral position" and the load-deflection ratio were also calculated. RESULTS: TLSs preactivated by curvature delivered horizontal forces significantly lower than those preactivated by concentrated bends. No differences were found in relation to the moments produced throughout the deactivation of both groups. The moment-to-force ratios were systematically higher on the TLSs preactivated by curvature than those preactivated by concentrated bends, except on 5 mm of activation. Significant differences were found in the load-deflection rates and "neutral position." CONCLUSIONS: The TLSs preactivated by curvature delivered lower horizontal forces and higher moment-to-force and load-deflection ratios than did those preactivated by concentrated bends.

Effects of stress relaxation in beta-titanium orthodontic loops.

INTRODUCTION: This study evaluates the changes in the force system of the beta-titanium T-loop spring (TLS) caused by stress relaxation. METHODS: Ninety TLSs with dimensions of 6 × 10 mm, made of 0.017 × 0.025-in beta-titanium alloy and preactivated by concentrated bends, were randomly distributed into 9 groups according to the time point of evaluation. Group 1 was tested immediately after spring preactivation and stress relief by trial activation. The other 8 groups were tested after 24, 48, and 72 hours, and 1, 2, 4, 8, and 12 weeks. By using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amounts of horizontal forces and moments and the moment-to-force ratios were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation in an interbracket distance of 23 mm. RESULTS: The horizontal forces and moments were higher (P <0.001) for group 1 compared with the other 8 groups, which were not different among themselves. All groups produced similar moment-to-force ratios (P = 0.600), with no influence of time. CONCLUSIONS: The TLSs preactivated by concentrated bends had progressive load decreases over time, and this effect is critical in the first 24 hours.

Optimizing the design of preactivated titanium T-loop springs with Loop software.

A TMA (Ormco Corp, Glendora, Calif) T-loop spring (TTLS), preactivated with a gable bend distal to the loop, holds promise for producing controlled tipping of the canines and translation of the posterior segment. However, there is currently no consensus as to where the preactivated gable bend or the loop should be placed, what the height of the loop should be, or how the interbracket distance changes the moments produced. Using the Loop software program (dHal, Athens, Greece), we systematically modified a .017 x .025-in TTLS (10 x 6 mm) that was preactivated with a 45 degrees gable bend distal to the loop, and simulated the effects. As the gable bend was moved posteriorly, the moment increased at the posterior bracket more than it decreased at the anterior bracket. As the loop was brought closer to the anterior bracket, the posterior moment decreased at the same rate that it increased anteriorly. As the loop was increased in size, the moments increased both posteriorly and anteriorly. As the interbracket distance increased, the posterior moment decreased, and the anterior moment remained constant. We concluded that the size of the loop should be slightly increased, to 10 x 7 mm, and it should be placed 2 mm from the anterior bracket, with a preactivation bend of 45 degrees , 4 to 5 mm from the posterior bracket (after 4 mm of activation).

Skeletal and dental components of Class II correction with the bionator and removable headgear splint appliances.

INTRODUCTION: The purpose of this study was to differentiate the dentoalveolar and skeletal effects to better understand orthodontic treatment. We evaluated the treatment changes associated with the bionator and the removable headgear splint (RHS). METHODS: The sample comprised 51 consecutively treated Class II patients from 1 office who had all been successfully treated with either a bionator (n=17) or an RHS appliance (n=17). Class II patients waiting to start treatment later served as controls (n=17). A modified version of the Johnston pitchfork analysis was used to quantify the dentoalveolar and skeletal contributions to the anteroposterior correction at the levels of the molars and the incisors. RESULTS: Both appliances significantly improved anteroposterior molar relationships (2.15 mm for the bionator, 2.27 mm for the RHS), primarily by dentoalveolar modifications (1.49 and 2.36 mm for the bionator and the RHS, respectively), with greater maxillary molar distalization in the RHS group. Overjet relationships also improved significantly compared with the controls (3.11 and 2.12 mm for the bionator and the RHS, respectively), due primarily to retroclination of the maxillary incisors (2.2 and 2.38 mm for the bionator and the RHS, respectively). The differences between overall corrections and dentoalveolar modifications for both molar and overjet relationships were explained by skeletal responses, with the bionator group showing significantly greater anterior mandibular displacement than the RHS group. CONCLUSIONS: The bionator and the RHS effectively corrected the molar relationships and overjets of Class II patients primarily by dentoalveolar changes.

Effects of reducing light-curing time of a high-power LED device on shear bond strength of brackets.

PURPOSE: To assess the effects of reducing the curing time of a high-power light-emitting diode (LED) unit (Valo, Ultradent, South Jordan, UT, USA) on shear bond strength (SBS) of metal brackets and on the amount of adhesive remnant of two orthodontic composites. METHODS: Eighty human premolars were divided into four groups (G1-4) according to curing time and composite: G1 (Transbond XT, 6 s), G2 (Opal Bond MV, 6 s), G3 (Transbond XT, 3 s), and G4 (Opal Bond MV, 3 s). Twenty-four hours after bonding, brackets were subject to a SBS test performed with a universal testing machine. Enamel surface was analyzed by SEM and the amount of adhesive remnant was assessed by the Image J software area calculation tool. Two-way analysis of variance was used for statistical analysis of SBS data, while Friedman and Mann-Whitney post hoc tests were used to analyze data on the amount of adhesive remnant. RESULTS: Time and composite significantly affected SBS (p < 0.001). The 6 s curing showed a higher SBS value (21.56 MPa) in comparison to 3 s curing (15.79 MPa). Transbond XT composite showed a significantly higher SBS value (21.06 MPa) compared to Opal Bond MV (16.29 MPa). After the SBS test, Opal Bond MV showed a significantly greater amount of composite adhered to enamel (p < 0.001). CONCLUSION: Reducing exposure time from 6 to 3 s significantly decreased mean values of SBS, even with the use of a high-power LED unit. Reduction in time did not affect the amount of adhesive remnant.

Welding strength of NiTi wires.

OBJECTIVE: To identify the appropriate power level for electric welding of three commercial brands of nickel-titanium (NiTi) wires. METHODS: Ninety pairs of 0.018-in and 0.017 × 0.025-in NiTi wires were divided into three groups according to their manufacturers - GI (Orthometric, Marília, Brazil), GII (3M OralCare, St. Paul, CA) and GIII (GAC,York, PA) - and welded by electrical resistance. Each group was divided into subgroups of 5 pairs of wires, in which welding was done with different power levels. In GI and GII, power levels of 2.5, 3, 3.5, 4, 4.5 and 5 were used, while in GIII 2.5, 3, 3.5 and 4 were used (each unit of power of the welding machine representing 500W). The pairs of welded wires underwent a tensile strength test on an universal testing machine until rupture and the maximum forces were recorded. Analysis of variance (ANOVA) and post-hoc tests were conducted to determine which subgroup within each brand group had the greatest resistance to rupture. RESULTS: The 2.5 power exhibited the lowest resistance to rupture in all groups (43.75N for GI, 28.41N for GII and 47.57N for GIII) while the 4.0 power provided the highest resistance in GI and GII (97.90N and 99.61N, respectively), while in GIII (79.28N) the highest resistance was achieved with a 3.5 power welding. CONCLUSIONS: The most appropriate power for welding varied for each brand, being 4.0 for Orthometric and 3M, and 3.5 for GAC NiTi wires.

Evaluation of the load system produced by a single intrusion bend in a maxillary lateral incisor bracket with different alloys.

OBJECTIVES: To evaluate if a 0.5-mm vertical bend applied on an incisor bracket produces movements in other planes and if different wires influence these effects. MATERIALS AND METHODS: An acrylic model of a treated patient with brackets passively bonded was attached to an Orthodontic Force Tester, and a load cell was attached to the left lateral incisor. Thirty 0.019 × 0.025-inch archwires were divided into three groups according to their alloy: SS (stainless steel), B-Ti (beta-titanium), and MF (beta-titanium wire coated with nickel-titanium). Step-bends of 0.5 mm high were placed on the lateral incisor bracket using a universal plier, and the forces and moments in three dimensions were statistically analyzed by analysis of variance and Tukey post hoc test. RESULTS: SS produced a larger force (3.4 N) than the B-Ti (1.41 N) and the MF (0.53 N; P < .001). Lingual forces were produced by the SS (0.82 N) and B-Ti (0.31 N) groups, while in the MF group, the force was insignificant. SS produced a mesial force of 0.24 N, while the B-Ti force was insignificant and MF produced 0.09 N. Groups produced different crown-distal tipping moments (SS = 31.48 N-mm, B-Ti = 11.7 N-mm, and MF = 4.55 N-mm) and different crown-buccal tipping moments. SS produced larger moments (3.63 N-mm) than B-Ti (1.02 N-mm) and MF (0.36 N-mm) wires. A mesial-out rotational moment was observed in all groups (SS = 7.17 N-mm, B-Ti = 3.46 N-mm, and MF = 0.86 N-mm). CONCLUSIONS: A 0.5-mm intrusion bend produced lingual and mesial side effects. In addition to the distal and buccal crown-tipping moments, there was a mesial-out moment. Compared with SS, B-Ti and MF wires produced lower forces. These more flexible wires showed side effects with lesser intensity.

Deformation of nickel-titanium closed coil springs: an in vitro study.

OBJECTIVE: The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs. METHODS: A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically. The values were compared by analysis of variance and Tukey's post-hoc test. RESULTS: Springs manufactured by Morelli had the same amount of deformation when they were activated up to 700% of Y activation; springs by Orthometric had the same amount of deformation up to 600-700% of Y; springs by Ormco had the same amount of deformation up to 700-800% of Y; and finally, the majority of springs by GAC had similar deformation up to 800%-1000% of activation. All springs tested could be activated up to 700% without rupture. CONCLUSIONS: Most subgroups were similarly deformed up to 700% of activation, without rupture of springs. Subgroups 4B, 4C, 4D and 4E showed the same amount of deformation up to 1000% of activation without any rupture at all.

Stability of beta-titanium T-loop springs preactivated by gradual curvature.

OBJECTIVE: Evaluate changes in the force system of T-Loop Springs (TLS) preactivated by curvature, due to stress relaxation. METHODS: Ninety TLSs measuring 6 x 10 mm, produced out with 0.017 x 0.025-in TMA® wire and preactived by gradual curvature, were randomly distributed into nine groups according to time point of evaluation. Group 1 was tested immediately after spring preactivation and stress relief, by trial activation. The other eight groups were tested after 24, 48 and 72 hours, 1, 2, 4, 8 and 12 weeks, respectively. Using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amount of horizontal force, moment and moment-to-force ratios were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation, in an interbracket distance of 23 mm. RESULTS: The horizontal forces decreased gradually among the groups (p< 0.001) and the moments showed a significant and slow decrease over time among the groups (p< 0.001). All groups produced similar M/F ratios (p= 0.532), with no influence of time. CONCLUSIONS: The TLSs preactivated by curvature suffered a gradual deformation over time, which affected the force system, specifically the moments, which affected the horizontal forces produced.

Combined periodontal, orthodontic, and restorative treatment of pathologic migration of anterior teeth: a case report.

Pathologic tooth migration related to periodontal disease is a common chief complaint of periodontal patients. This paper describes the treatment of a case of severe periodontal disease and disfiguring pathologic migration of maxillary central incisors, which required a multidisciplinary approach. After conventional periodontal treatment was performed, the anterior diastema was closed using a combination of orthodontic therapy and restorative treatment. A 6-month follow-up examination of this case revealed resolution of the anterior pathologic migration, with gains in clinical attachment levels and a successful esthetic and functional final result.

Superelasticity and force plateau of nickel-titanium springs: an in vitro study.

OBJECTIVE: This paper analyzed whether nickel-titanium closed coil springs (NTCCS) have a different superelastic (SE) behavior according to activation and whether their force plateau corresponds to that informed by the manufacturer. METHODS: A total of 160 springs were divided into 16 subgroups according to their features and activated proportionally to the length of the extensible part (NiTi) of the spring (Y). The force values measured were analyzed to determine SE rates and force plateaus, which were mathematically calculated. These plateaus were compared to those informed by the manufacturer. Analysis of variance was accomplished followed by Tukey post-hoc test to detect and analyze differences between groups. RESULTS: All subgroups were SE at the activation of 400% of Y length, except for: subgroups 4B and 3A, which were SE at 300%; subgroups 4E and 4G, which were SE at 500%; and subgroup 3C, which was SE at 600%. Subgroup 3B did not show a SE behavior. Force plateaus depended on activation and, in some subgroups and some activations, were similar to the force informed. CONCLUSIONS: Most of the springs showed SE behavior at 400% of activation. Force plateaus are difficult to compare due to lack of information provided by manufacturers.

Comparison surface characteristics and chemical composition of conventional metallic and nickel-free brackets.

This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracket surface was performed using SEM, whereby surface features were described and compared. The elemental composition was analyzed by EDS. According to surface analysis, groups ABZ and RL showed a homogeneous surface, with better finishing, whereas the surfaces in groups NF and RM were rougher. The chemical components with the highest percentage were Fe, Cr and C. Groups NF and MR showed no nickel in their composition. In conclusion, the bracket surface of the ABZ and RL groups was more homogeneous, with grooves and pores, whereas the surfaces in groups NF and RM showed numerous flaws, cracks, pores and grooves. The chemical composition analysis confirmed that the nickel-free brackets had no Ni in their composition, as confirmed by the manufacturer's specifications, and were therefore safe to use in patients with a medical history of allergy to this metal.

Differences in the force system delivered by different beta-titanium wires in elaborate designs.

OBJECTIVE: Evaluation of the force system produced by four brands of b-Ti wires bent into an elaborate design. METHODS: A total of 40 T-loop springs (TLS) hand-bent from 0.017 x 0.025-in b-Ti were randomly divided into four groups according to wire brand: TMATM(G1), BETA FLEXYTM (G2), BETA III WIRETM (G3) and BETA CNATM (G4). Forces and moments were recorded by a moment transducer, coupled to a digital extensometer indicator adapted to a testing machine, every 0.5 mm of deactivation from 5 mm of the initial activation. The moment-to-force (MF) ratio, the overlapping of the vertical extensions of the TLSs and the load-deflection (LD) ratio were also calculated. To complement the results, the Young's module (YM) of each wire was determined by the slope of the load-deflection graph of a tensile test. The surface chemical composition was also evaluated by an energy dispersive X-ray fluorescence spectrometer. RESULTS: All groups, except for G2, produced similar force levels initially. G3 produced the highest LD rates and G1 and G4 had similar amounts of overlap of the vertical extensions of the TLSs in "neutral position". G1 and G3 delivered the highest levels of moments, and G2 and G3 produced the highest MF ratios. b-Ti wires from G3 produced the highest YM and all groups showed similar composition, except for G2. CONCLUSION: The four beta-titanium wires analyzed produced different force systems when used in a more elaborate design due to the fact that each wire responds differently to bends.