Objective While all manufacturers of orthodontic brackets label these products for single use, there are commercial providers offering bracket reconditioning (or ?recycling?). We conducted this study to investigate the effects of different recycling techniques on material-related parameters in orthodontic brackets, aiming to derive indications for clinical use and conclusions about the biocompatibility, longevity, and application of recycled brackets. Materials and methods New metal brackets (equilibrium®; Dentaurum, Ispringen, Germany) were compared to brackets recycled by different techniques, including direct flaming with a Bunsen burner, chemical reconditioning in an acid bath, a commercial unit (Big Jane; Esmadent, IL, USA), and outsourcing to a company (Ortho Clean, Dellstedt, German...

IntroductionThis study aimed to assess the effect of clinical exposure on the surface morphology, dimensions, and frictional behavior of metallic orthodontic brackets. MethodsNinety-five brackets, of 3 commercial brands, were retrieved from patients who had finished orthodontic treatment. As-received brackets, matched by type and brand, were used for comparisons. Surface morphology and precipitated material were analyzed by optical and scanning electron microscopy and x-ray microanalysis. Bracket dimensions were measured with a measuring microscope. Resistance to sliding on a stainless steel wire was assessed. ResultsRetrieved brackets showed surface alterations from corrosion, wear, and plastic deformation, especially in the external slot edges. Film deposition over the alloy surface was ...

In orthodontics, a combination of metallic alloys is placed into the oral cavity during medical treatment and thus the corrosion resistance and ionic release of these appliances is of vital importance. The aim of this study is to investigate the elemental composition, microstructure, hardness, corrosion properties, and ionic release of commercially available orthodontic brackets and Copper Ni-Ti archwires. Following the assessment of the elemental composition of the orthodontic wire (Copper Ni-Ti) and the six different brackets (Micro Loc, Equilibrium, OptiMESH(XRT), Gemini, Orthos2, and Rematitan), cyclic polarization curves were obtained for each material to estimate the susceptibility of each alloy to pitting corrosion in 1M lactic acid. Galvanic corrosion between the orthodontic wire and each bracket took place in 1M lactic acid for 28 days at 37 degrees C and then the ionic concentration of Nickel and Chromium was studied. The orthodontic wire is made up from a Ni-Ti alloy with copper additions, while the orthodontic brackets are manufactured by different stainless steel grades or titanium alloys. All tested wires and brackets with the exception of Gemini are not susceptible to pitting corrosion. In galvanic corrosion, following exposure for 28 days, the lowest potential difference (approximately 250 mV) appears for the orthodontic wire Copper Ni-Ti and the bracket made up from pure titanium (Rematitan) or from the stainless steel AISI 316 grade (Micro Loc). Following completion of the galvanic corrosion experiments, measurable quantities of chromium and nickel ions were found in the residual lactic acid solution. PMID:16969817

In orthodontics, a combination of metallic alloys is placed into the oral cavity during medical treatment and thus the corrosion resistance and ionic release of these appliances is of vital importance. The aim of this study is to investigate the elemental composition, microstructure, hardness, corrosion properties, and ionic release of commercially available orthodontic brackets and Copper Ni-Ti archwires. Following the assessment of the elemental composition of the orthodontic wire (Copper Ni-Ti) and the six different brackets (Micro Loc, Equilibrium, OptiMESHXRT, Gemini, Orthos2, and Rematitan), cyclic polarization curves were obtained for each material to estimate the susceptibility of each alloy to pitting corrosion in 1M lactic acid. Galvanic corrosion between the orthodontic wire and...

Huang Y., Keilig L., Rahimi A., Reimann S., Bourauel C: Torque capabilities of self-ligating and conventional brackets under the effect of bracket width and free wire length Orthod Craniofac Res 2012;15:255-262. © John Wiley & Sons A/S STRUCTURED ABSTRACT: Objectives?-? To numerically investigate the torque capacity of conventional and self-ligating brackets under the effect of varying bracket width and free wire length. Material and Methods?-? Finite element models of three kinds of orthodontic brackets in the 0.022-inch slot size were investigated: Discovery, Damon 3MX, Speed. Additionally, finite element (FE) models of Speed and Damon brackets were generated with the same width as the Discovery. From the left upper incisor to the right upper canine, four brackets each were modelled. The total wire length at the upper right incisor was kept constant at 12?mm for all brackets types. For the Discovery brackets, the wire length was increased from 12 to 16?mm in 2-mm steps. A torque of 20° was applied to the upper right incisor with 0.46?×?0.64?mm(2) (0.018??×?0.025?) and 0.48?×?0.64?mm(2) (0.019??×?0.025?) wires. Wires made of stainless steel, titanium molybdenum and nickel titanium were studied. Torque angle/moment characteristics were recorded. Results?-? Wider brackets showed more torque control capability (e.g. Discovery: 10.6?Nmm, Damon: 9.2?Nmm, Speed: 4.0?Nmm for the NiTi wire). Even with the same width as the Discovery bracket, Damon and Speed brackets showed lower torque capability than the Discovery bracket. Increasing the free wire length decreased the torsional stiffness of the wire and thus decreased the torque capability. Conclusion?-? The results showed that the bracket design has less influence on the torquing moment than other parameters, such as bracket width, free wire length, wire/slot play or misalignment. PMID:23020696

The influence of temperature and relative humidity (RH) on the bond strength of orthodontic adhesives was investigated. Two self-etching/composite type, one acid-etching/composite type, and one acid-etching/PMMA type of adhesives were examined under different temperature and RH conditions. Orthodontic brackets were bonded to bovine enamel, and shear bond strength test was performed at a crosshead speed of 1.0 mm/min after 24-hour storage in 37°C water. Data were analyzed by Tukey's HSD test. Each specimen was assigned an ARI score. All the materials tested exhibited their highest bond strength under room conditions at a range of 10.4–17.0 MPa. Conversely, when under a lower RH condition, bond strength for all the systems ranked the lowest within a range of 6.8–12.0 MPa, with bond failure at the bracket—adhesive interface. These results demonstrated that care should be exercised when using orthodontic adhesive systems in the oral environment.   

The purpose of this 2-part opinion article was to project the developments expected to occur in the next few years in orthodontic materials research and applications. Part 1 reviewed developments in bonding to enamel. Part 2 looks at other orthodontic materials applications and explores emerging research strategies for probing the biological properties of materials. In the field of metallic brackets, expansion of the use of titanium alloys with improved hardness and nickel-free steels with better corrosion resistance and increased hardness is expected. Manufacturing techniques might be modified to include laser-welding methods and metal injection molding. Esthetic bracket research will involve the synthesis of high-crystallinity biomedical polymers with increased hardness and stiffness, de...

The effect of fluoride-containing orthodontic resin bonding systems on acid resistance of adjacent enamel was evaluated using transversal microradiography. Four fluoride-containing orthodontic resin bonding systems : BeautyOrtho Bond (BO), BeautyOrtho Bond+Salivatect (BOS), Kurasper F (KP), Transbond XT (TB) and a resin-modified glass-ionomer (Fuji Ortho LC (FO)) were used. Superbond Orthomite (SB) was used as a non-fluoride material. Rectangular bovine enamel specimens (10×6 mm) were prepared. After curing the materials, nail varnish was applied to the enamel surfaces, leaving a gap of 1 mm from the cured material's periphery. The specimens were demineralized with 8% Methocel MC gel and 0.1 M lactic acid. BO, BOS, and FO revealed shallow lesions and distinct surface layers. The mineral losses of BO, BOS, and FO were significantly lower than those of TB, KP, and SB (p<0.05). In conclusion, the new system induced superior acid resistance in enamel surrounding orthodontic brackets.   

IntroductionThe 3-dimensional load system (forces and moments) was quantified at the canine bracket during space closure with sliding mechanics with elastomeric chain on dry and wet stainless steel and beta-titanium 0.019 x 0.025-in archwires. MethodsA custom-made maxillary dentoform simulating first premolar extractions was attached to an orthodontic force tester. The canine was attached to a load cell through an adaptor with silicone simulating the periodontal ligament. The orthodontic force tester simultaneously measured the entire load system produced at the canine bracket by an elastomeric chain. The effects of archwire material, time (activation and 1 hour), and lubrication were analyzed by using 3-way repeated measures analysis of variance (ANOVA, a = 0.05). ResultsStainless steel p...

Teflon is an anti-adherent and aesthetic material. The aim of this study was to evaluate, in vitro, the influence of Teflon coating on the resistance to sliding (RS) of orthodontic archwires. For this purpose, Teflon-coated archwires were examined using frictional resistance tests by means of a universal testing machine and compared with conventional uncoated wires. Twelve types of archwires with round and rectangular sections (0.014, 0.018, and 0.018 x 0.025 inches) and of different materials (stainless steel and nickel-titanium) were tested with two passive self-ligating brackets (SmartClip and Opal) and one active self-ligating bracket (Quick). Each archwire-bracket combination was tested 10 times under 8 simulated clinical scenarios. Statistical comparisons were conducted between the u...

Abstract in portuguese OBJETIVO: avaliar, in vitro, a biodegradação de aparelhos ortodônticos simulados constituídos de braquetes e fios de aço inoxidável. METODOLOGIA: a amostra foi dividida em 2 grupos, de acordo com a marca dos braquetes usados: grupo A - Dyna-Lock, 3M/Unitek (AISI 303); e grupo B - LG Edgewise Standard, American Orthodontics (AISI 316L). Os corpos-de-prova permaneceram incubados em solução salina (0,05%) a 36ºC, sob agitação por um período de até 60 dias. A an? (more) ?lise da liberação iônica foi realizada por meio de espectrofotometria de absorção atômica. O peso em massa dos braquetes também foi medido antes e após o experimento. RESULTADOS: os resultados indicaram que o grupo A apresentou maior liberação de íons ferro, níquel e cromo do que o grupo B. Além disso, os braquetes do grupo A também mostraram perda de massa, considerada outro indicativo de corrosão. CONCLUSÃO: concluiu-se que, nas condições deste experimento, os braquetes do grupo A apresentaram maior biodegradação que os acessórios do grupo B, o que pode estar associado à liga metálica e/ou ao processo de fabricação dos mesmos. Abstract in english OBJECTIVE: The purpose of this study was to evaluate, in vitro, the biodegradation of simulated orthodontic appliances consisting of stainless steel brackets and wires. MATERIALS AND METHODOS: The sample was divided in 2 groups, according to brackets brand: group A - Dyna-Lock, 3M/ Unitek (AISI 303); and group B - LG Edgewise Standard, American Orthodontics (AISI 316L). The specimens (simulated orthodontic appliances) were incubated in saline solution (0.05%), in shake, a (more) t 36ºC, for 60 days. The ion release was detected by atomic absorption spectrophotometer. The weight of brackets was also measured before and after the test. RESULTS: The results indicated that group A released more ions iron, nickel and chromium than group B. Moreover, the brackets in group A also presented weight loss, which is considered an indicator of corrosion. CONCLUSION: It was concluded that, under the present study conditions, the brackets from group A presented a higher biodegradation than group?s B brackets, what could be associated to composition and manufacturing process of these brackets.

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 orthodontic treatment with SS self-ligating brackets may require smaller orthodontic forces than that with ceramic self-ligating brackets or conventional SS brackets. PMID:22188518

Summary 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...

The corrosion of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37 degrees C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L. The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires. PMID:9228844

... If you wear braces or another fixed dental appliance on your lower jaw, your dentist may suggest ... could damage the brackets or other fixed orthodontic appliances. A mouthguard also provides a barrier between the ...

Abstract in english OBJECTIVE: This study evaluated the glass transition temperature (Tg) and degree of conversion (DC) of a light-cured (Fill Magic) versus a chemically cured (Concise) orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different (more) exposure times (40, 90 and 120 s). RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC), but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.

... continuous mild force through the use of an orthodontic appliance, such as braces (wires and springs carried by brackets that are fixed ... adhesive) or a retainer (a removable brace combining wires and a plastic ... malocclusions, orthodontic therapy can be done with appliances that are ...

Friction between archwires and labial brackets has received considerable attention; however, information on the frictional behaviour of commercially available lingual brackets is limited. The aim of this study was to investigate the frictional resistance resulting from a combination of lingual orthodontic brackets (7th Generation, STb, Magic, and In-Ovation L) and stainless steel archwires at 0, 5, and 10 degrees of second-order angulation. Each bracket type (n = 30) was tested with three different sizes of archwires. Static and kinetic frictional forces were evaluated with a universal testing machine. Statistical analysis of the data was performed with non-parametric Kruskal-Wallis and Dunn's multiple comparison tests. All tested brackets showed higher frictional forces as the wire size and second-order angulation increased. The lowest friction was found with In-Ovation L brackets and 0.016 inch archwires at 0 degrees angulation, and the greatest friction with a combination of STb brackets and 0.017 × 0.025 inch archwires at 10 degrees angulation. For all combinations, Magic and In-Ovation L brackets showed lower frictional resistance when compared with 7th Generation and STb brackets. The slot width (occluso-gingival dimension) of the brackets, measured using the optics of a microhardness machine, showed that all brackets were oversized and that Magic brackets had the largest slot width. Surface roughness of the brackets investigated using atomic force microscopy and scanning electron microscopy, demonstrated that the 7th Generation brackets had the greatest surface roughness. PMID:21239394

The shear bond strength (SBS) of a light-cured, resin-reinforced glass ionomer and a composite adhesive in combination with a self-etching primer was compared after different setting times to evaluate when orthodontic wires could be placed. Additionally, the fracture site after debonding was assessed using the Adhesive Remnant Index (ARI). Eighty freshly extracted human premolars were used. Twenty teeth were randomly assigned to each of four groups: (1) brackets bonded with Transbond XT with a Transbond Plus etching primer and debonded within 5 minutes; (2) brackets bonded with Fuji Ortho LC and debonded within 5 minutes; (3) brackets bonded as for group 1 and debonded within 15 minutes; (4) brackets bonded as for group 2 and debonded within 15 minutes. The SBS of each sample was determined with an Instron machine. The mean SBS were, respectively: (1) 8.8 +/- 2 MPa; (2) 6.6 +/- 2.5 MPa; (3) 11 +/- 1.6 MPa and (4) 9.6 +/- 1.6 MPa. Interpolating the cumulative fracture probability by means of a Weibull analysis, the 10 per cent probabilities of fracture for the groups were found to be attained for shear stresses of 6.1, 3.1, 8.3 and 7.1 MPa, respectively. Chi-square testing of the ARI scores revealed that the nature of the remnant did not vary significantly with time, but the type of bonding material could generally be distinguished in leaving more or less than 10 per cent of bonding material on the tooth. After debonding, the Transbond system was likely to leave adhesive on at least 10 per cent of the bonded area of the tooth. The present findings indicate that brackets bonded with either Transbond XT in combination with Transbond Plus etching primer and Fuji Ortho LC had adequate bond strength at 5 minutes and were even stronger 15 minutes after initial bonding. PMID:16043469

Abstract Objective: To quantify the three-dimensional moments and forces produced by pretorqued nickel-titanium (NiTi) rectangular archwires fully engaged in 0.018- and 0.022-inch slots of central incisor and molar edgewise and prescription brackets. Materials and Methods: Ten identical acrylic dental models with retroclined maxillary incisors were fabricated for bonding with various bracket-wire combinations. Edgewise, Roth, and MBT brackets with 0.018- and 0.022-inch slots were bonded in a simulated 2 × 4 clinical scenario. The left central incisor and molar were sectioned and attached to load cells. Correspondingly sized straight and pretorqued NiTi archwires were ligated to the brackets using 0.010-inch ligatures. Each load cell simultaneously measured three force (F(x), F(y), F(z)) and three moment (M(x), M(y), M(z)) components. The faciolingual, mesiodistal, and inciso-occluso/apical axes of the teeth corresponded to the x, y, and z axes of the load cells, respectively. Each wire was removed and retested seven times. Three-way analysis of variance (ANOVA) examined the effects of wire type, wire size, and bracket type on the measured orthodontic load systems. Interactions among the three effects were examined and pair-wise comparisons between significant combinations were performed. Results: The force and moment components on each tooth were quantified according to their local coordinate axes. The three-way ANOVA interaction terms were significant for all force and moment measurements (P .05). Conclusion: The pretorqued wire generates a significantly larger incisor facial crown torquing moment in the MBT prescription compared to Roth, edgewise, and the straight NiTi wire. PMID:23095073

Abstract in portuguese OBJETIVO: o objetivo deste estudo foi verificar a fricção no braquete (Roth, Composite, 10.17.005, 3,2mm, largura 0,022" x 0,030", Torque -2° e angulação +13°, Morelli®, Brasil), utilizando fios ortodônticos retangulares de 0,019" x 0,025" de aço inoxidável (Morelli®, Brasil) e de níquel-titânio superelásticos Bioforce com IonGuard e sem IonGuard (Bioforce, GAC®, EUA). MÉTODOS: foram utilizados 24 conjuntos braquetes/segmento de fio, divididos em 3 grupos (more) de acordo com o fio. Cada conjunto braquete/segmento de fio foi testado 3 vezes e obtida uma média. Os ensaios foram realizados em máquina universal de ensaios EMIC DL2000®. Os dados foram submetidos à Análise de Variância com significância de 95%. RESULTADOS: o fio retangular Bioforce com IonGuard apresentou fricção significativamente menor que o Bioforce sem IonGuard, porém sem diferença do fio de aço inoxidável. Entretanto, o coeficiente de variação dos fios Bioforce com e sem IonGuard foi menor que o do fio de aço inoxidável. CONCLUSÃO: os fios retangulares de 0,019" x 0,025" Bioforce com IonGuard apresentam menor fricção que o fio Bioforce sem IonGuard, sem diferença para o fio de aço inoxidável. Abstract in english OBJECTIVE: The aim of this study was to evaluate the friction forces on brackets (Roth, Composite, 10.17.005, 3.2 mm, width 0.022" x 0.030 ", Torque -2° and angulation +13°, Morelli®, Brazil), with stainless steel orthodontic rectangular wire (Morelli®, Brazil) and nickel titanium superelastic Bioforce wires with and without IonGuard (Bioforce, GAC®, USA). MATERIAL AND METHODS: Twenty-four brackets/wire segment combinations were used, distributed into three groups ac (more) cording to the orthodontic wire. Each bracket/wire segment combination was tested three times. The tests were performed in a universal testing machine Emic DL2000®. The data was submitted to ANOVA one way followed by Tukey's post hoc test (p

Introduction The aims of this study were to evaluate the in-vivo reaction of newly erupted enamel to demineralization around orthodontic brackets and to compare it with that of mature enamel. Methods Thirteen orthodontic patients scheduled to have 4 first premolars extracted for orthodontic reasons were divided into 2 groups. Group 1 included 7 younger patients with newly erupted teeth (4 boys, 3 girls; mean age, 11.21 +- 1.12 years; range, 11-13 years). Group 2 contained 6 adults with mature teeth (5 men, 1 woman; mean age, 34.64 +- 4.01 years; range, 25-41 years). Brackets were placed, and, 30 days later, the teeth were extracted. These teeth were longitudinally sectioned, and demineralization was assessed by cross-sectional microhardness. Determinations were made at the bracket-edge com...

As new adhesives, composite resins, and bonding techniques were introduced, orthodontists adopted some of these innovations and added them to their armamentarium. The purpose of this study was to compare the shear bond strength (SBS) of two adhesive materials; one with an organically modified ceramic matrix, Admira (Voco, Cuxhaven, Germany) and another that contains the traditional Bis GMA matrix namely Transbond XT (3M Unitek, Monrovia, Calif). The new materials have a lower wear rate and are more biocompatible than traditional composites. Forty molar teeth were randomly divided into two groups: 20 teeth bonded with the Transbond adhesive system and the other 20 teeth with the Admira bonding system. Student's t-test was used to compare the SBS of the two adhesives. Significance was predetermined at P Ormocer, which is an organically modified ceramic restorative material can potentially have orthodontic applications if available in a more flowable paste. These new materials are more biocompatible and have lower wear rate including bonding orthodontic brackets to teeth. PMID:15747824

Austenitic stainless steels containing approximately 18 percent chromium and 8 percent nickel for orthodontic bands, brackets and wires is universally used in orthodontic practices. With the introduction of nickel-titanium alloys as orthodontic archwires in the 1970's an additional source of patient exposure to metal corrosion products has been introduced. Since the oral environment is particularly ideal for the biodegradation of metals due to its ionic, thermal, microbiologic and enzymatic properties some level of patient exposure to the corrosion products of these alloys is assured.

Abstract Objective: The aim of this study was to determine the shear bond strength (SBS), etching pattern and depth, and debonding performance of several market-leading, self-etching (SE) adhesives primarily used in restorative dentistry (iBond?, Clearfil? S3 Bond, Clearfil? Protect Bond, AdheSE?, Xeno?III), two experimental self-etching adhesives (exp. Bond 1, exp. Bond 2) and one experimental self-etching cement (SE Zement) used with and without prior phosphoric acid-etching, and to compare them to an orthodontic self-etching product (Transbond? Plus SE Primer) and to traditional acid-etch technique (Transbond? XT Primer, phosphoric acid) Materials and Methods: All adhesives were applied on pumiced and embedded bovine incisors following the manufacturers' instructions. Then one bracket e...

Abstract Objective: The purpose of this study was to evaluate the effects of antimicrobial pretreatments [chlorhexidine gluconate (CHX), Clearfil Protect Bond (CPB), and potassium-titanyl-phosphate (KTP) laser] on microleakage under metal orthodontic brackets. Materials and Methods: Sixty freshly-extracted human premolars were randomly assigned to four equal groups: group 1, 37% phosphoric acid; group 2, 37% phosphoric acid?+?2% CHX; group 3, 37% phosphoric acid?+?KTP laser; and group 4, CPB. The teeth were kept in distilled water for 24?h, and thereafter subjected to 500 thermal cycles. Then specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24?h, sectioned, and evaluated under a stereomicroscope. Microleakage was scored with regard to the adhesive?tooth interfac...

IntroductionControl of root torque is often achieved by introducing a twist in a rectangular archwire. The purpose of this study was to investigate third-order torque on different types of self-ligated brackets by analyzing the bracket’s elastic and plastic deformations in conjunction with the expressed torque at varying angles of twist. MethodsAn orthodontic bracket was mounted to a load cell that measured forces and moments in all directions. The wire was twisted in the bracket via a stepper motor, controlled by custom software. Overhead images were taken by a camera through a microscope and processed by using optical correlation to measure deformation. ResultsAt the maximum torquing angle of 63degree with 0.019 x 0.025-in stainless steel wire, the total elastic and plastic deform...

Abstract in portuguese OBJETIVO: avaliar a resistência ao cisalhamento de braquetes metálicos (American Orthodontics) utilizados na técnica lingual, colados em facetas de cerâmica. MÉTODOS: foram utilizados 40 corpos de prova divididos em quatro grupos de 10, de acordo com o material de colagem e do preparo da porcelana: Grupo I -resina Sondhi Rapid-Set e ácido fluorídrico; Grupo II -resina Sondhi Rapid-Set e óxido de alumínio; Grupo III -resina Transbond XT e ácido fluorídrico; e Gr (more) upo IV -resina Transbond XT e óxido de alumínio. Previamente à colagem, os braquetes foram preparados com base de resina de carga pesada (Z-250) e as facetas de cerâmica receberam aplicação de silano. O teste de cisalhamento foi realizado por uma máquina de ensaios Kratos à uma velocidade de 0,5mm/min. RESULTADOS: os resultados obtidos foram analisados estatisticamente através do teste de Tukey (p Abstract in english OBJECTIVE: The aim of this study was to evaluate the shear strength of lingual metal brackets (American Orthodontics) bonded to ceramic veneers. METHODS: A total of 40 specimens were divided into four groups of 10, according to bonding material and ceramics preparation: Group I -Sondhi Rapid-Set resin and Hydrofluoric acid, Group II -Sondhi Rapid-Set resin and aluminum oxide, Group III -Transbond XT resin and Hydrofluoric acid, and Group IV -Transbond XT resin and aluminu (more) m oxide. Prior to bonding, the brackets were prepared with heavy-duty resin base (Z-250) and the ceramic veneers were treated with silane. The shear test was conducted with a Kratos testing machine at a speed of 0.5 mm/min. RESULTS: The results were statistically analyzed by the Tukey test (p

The aim of this study was to assess bonding of orthodontic metal brackets to porcelain surfaces using various surface treatment methods. Etching the porcelain with 9.6 percent HF followed by a bonding agent or silane application provided high and acceptable shear bond strengths. PMID:21192611

The purpose of this study was to evaluate the performance of modified 4-META/ MMA-TBB resin cements (Superbond C&B) in terms of debonding orthodontic brackets easily and safely from enamel without the loss of proper bracket bond strength. Poly(DL-lactide-co-glycolide) (PLGA), calcium fluoride (CaF2), or ?-tricalcium phosphate (?-TCP) was added to the polymer powder of 4-META/ MMA-TBB resin, and the shear bond strength of orthodontic brackets to human enamel using modified resins was measured before and after 10,000-cycle thermal cycling test between 5°C and 55°C. The modified resins tended to provide lower bond strength compared with the original 4-META/ MMA-TBB resin. However, ?-TCP- or CaF2-modified resin showed no significant differences in bond strength before and after thermal cycling. Moreover, there was a tendency of more residual resin remaining on the tooth surface after debonding, thereby suggesting a lower risk of enamel fracture. In conclusion, ?-TCP- or CaF2-modified 4-META/ MMA-TBB resin seemed to allow easy and safe debonding of orthodontic brackets without loss of proper bracket bond strength   

In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp2 carbon dominated structures, and diversiform bonds (NC, NC, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp2C rich structure of the CNx film as well as its protection function for the archwire was responsible for the low friction of the wire-bracket sliding system.

In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily doses, two elements of concern were nickel (573 vs. 15 ?g/l in the controls) and chromium (101 vs. 8 ?g/l in the controls). Three ion release coefficients were defined: ?, a dimensionless multiplication factor; ?, the difference in concentrations (in micrograms per liter); and ?, the ion release coefficient (in percent). The elevated levels of metals in saliva are thought to occur by corrosion of the chemical elements in the alloys or welding materials. The concentrations of some groups of dissolved elements appear to be interrelated. PMID:22011837

PURPOSE: The aim of this study was to investigate the occlusion, the demand for orthodontic treatment and the reasons for this among Chinese young adults in Hong Kong. MATERIALS AND METHODS: A questionnaire was used to study previous orthodontic experience and to evaluate the orthodontic treatment d...

Abstract in english The aim of this study was to determine whether image artifacts caused by orthodontic metal accessories interfere with the accuracy of 3D CBCT model superimposition. A human dry skull was subjected three times to a CBCT scan: at first without orthodontic brackets (T1), then with stainless steel brackets bonded without (T2) and with orthodontic arch wires (T3) inserted into the brackets' slots. The registration of image surfaces and the superimposition of 3D models were per (more) formed. Within-subject surface distances between T1-T2, T1-T3 and T2-T3 were computed and calculated for comparison among the three data sets. The minimum and maximum Hausdorff Distance units (HDu) computed between the corresponding data points of the T1 and T2 CBCT 3D surface images were 0.000000 and 0.049280 HDu, respectively, and the mean distance was 0.002497 HDu. The minimum and maximum Hausdorff Distances between T1 and T3 were 0.000000 and 0.047440 HDu, respectively, with a mean distance of 0.002585 HDu. In the comparison between T2 and T3, the minimum, maximum and mean Hausdorff Distances were 0.000000, 0.025616 and 0.000347 HDu, respectively. In the current study, the image artifacts caused by metal orthodontic accessories did not compromise the accuracy of the 3D model superimposition. Color-coded maps of overlaid structures complemented the computed Hausdorff Distances and demonstrated a precise fusion between the data sets.

Abstract in spanish Desde la introducción de la técnica de Edgewise por el Dr Edward Angle, pasando por la técnica de alambres ligeros de Begg, hasta la actualidad la ortodoncia ha experimentado diversas combinaciones y evoluciones dentro de las técnicas hasta llegar al diseño de los brackets de combinación tendencia actual en la fabricación de los mismos, en este trabajo se hace un recuento de la evolución de las brackets de combinación hasta los diseños mas actuales. Abstract in english From the introduction of the Edgewise technique by the Dr Edward Angle, going by the technique of light wires of Begg, until the present time the orthodontic has experienced diverse combinations and evolutions inside the techniques until arriving to the design of the combination brackets, current tendency in the production of the same ones, in this paper a recount of the evolution of the combination brackets is made until the current.

The aim of this in vitro study was to compare microleakage of orthodontic brackets between enamel-composite and composite-bracket interfaces at the occlusal and gingival margins, bonded using indirect bonding systems with that of a conventional direct bonding method. Forty freshly extracted human maxillary premolar teeth were randomly divided into two groups. In group 1, the brackets were bonded to teeth directly according to the manufacturer's recommendations. Group 2 consisted of 20 teeth bonded indirectly with Transbond XT (3M-Unitek), as the adhesive, and Sondhi Rapid Set A/B Primer (3M-Unitek), a filled resin primer. After bonding, the specimens were further sealed with nail varnish, stained with 0.5 per cent basic fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage at the enamel-composite and composite-bracket interfaces from both the occlusal and gingival margins. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction. The gingival sides of group 1 displayed a higher median microleakage score than the occlusal side at the enamel-composite interface but this was not statistically significant (P > 0.05). All occlusal margins in both groups showed no microleakage under orthodontic brackets at the enamel-composite or composite-bracket interfaces. Comparisons of the microleakage scores between the direct and the indirect bonding groups at the enamel-composite and composite-bracket interfaces indicated no statistically significant microleakage differences at the gingival and occlusal margins (P > 0.05). The type of bonding method (direct versus indirect) did not significantly affect the amount of microleakage at the enamel-composite-bracket complex. PMID:19752016

In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp^2 carbon dominated structures, and diversiform bonds (N?C, N?C, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp^2C rich structure of the CNx film as well as its protection function for the archwire was res...

The chief aim of this study was to evaluate the influence of three different types of pretreatment solutions (phosphoric acid, self-etching primers, and polyacrylic acid) on enamel surfaced when used in association with one of the five orthodontic adhesive systems. In the same vein, the shear bond strength of orthodontic metal brackets was also measured to evaluate the influence of bonding procedure. After the enamel surfaces of extracted human maxillary incisors were pretreated with the five adhesive systems, scanning electron microscopy (SEM) was used to observe the effects of pretreatment on enamel. Additionally, the shear bond strength of metal brackets bonded with the five adhesives was measured (n=6). SEM observation revealed different etching patterns on the enamel surface after pretreatment. As for shear bond strength, no statistically significant differences were observed among the five different adhesives (p>0.05). It was found that self-etching primers and polyacrylic acid produced a less aggressive etching pattern than phosphoric acid. Nonetheless, all the five adhesive systems provided acceptable bond strength and attachment of orthodontic brackets.   

...the finished automotive components' material value) include: adhesives, plastic fittings, plastic and rubber belts, fasteners, gaskets/seals/o- rings, metal fittings, labels, plastic wedging, springs, brackets, plates,...

IntroductionThe objective of this study was to demonstrate the potential of 3-dimensional modeling and finite element analysis as clinical tools in treatment planning for orthodontic tooth movement. High stresses in bone and miniscrew implants under load can cause fractures and trauma for orthodontic patients, and treatments are typically planned by using clinical experience or simple 2-dimensional radiographs. MethodsAnatomically accurate 3-dimensional models reconstructed from cone-beam computed tomography scans were used to simulate the retraction of a single-rooted mandibular canine with a miniscrew placed as skeletal anchorage. Detailed stress distributions in the implant and peri-implant bone were found, in addition to the effect of the orthodontic bracket hook length and the angulat...

IntroductionA digital plaque image analysis system was developed to objectively assess dental plaque formation and coverage in patients treated with fixed orthodontic appliances. MethodsThe technique was used to assess plaque levels of 52 patients undergoing treatment with fixed appliances in the Department of Orthodontics at Johannes Gutenberg University in Mainz, Germany. ResultsPlaque levels ranged from 5.1% to 85.3% of the analyzed tooth areas. About 37% of the patients had plaque levels over 50% of the dentition, but only 10% exhibited plaque levels below 15% of tooth coverage. The mean plaque coverage was 41.9% +- 18.8%. Plaque was mostly present along the gum line and around the orthodontic brackets and wires. ConclusionsThe digital plaque image analysis system might provide a conve...

The purpose of this study was to ascertain the effects of tooth bleaching on the shear bond strength of orthodontic brackets rebonded with a self-etching adhesive system. A total of 39 premolars were collected and divided into three equal groups: in group 1 bracket bonding was performed without bleaching treatment; specimens in group 2 were bonded immediately after bleaching; and group 3 teeth were bleached, then immersed in artificial saliva and left for 7 days before bonding. The shear bond strength was measured, with the bonding/debonding procedures repeated once after the first debonding, and the bracket/adhesive failure modes were evaluated by the adhesive remnant index after each debonding. Excepting the mean shear bond strength for group 2 after the first debonding, the overall mean...

IntroductionIt is unknown whether or not intraoral vibrations affect stick-slip behavior at orthodontic bracket-archwire interfaces. In this study, we evaluated bracket-archwire stick-slip behavior as a function of ligation method and archwire vibration. MethodsIn-vivo archwire vibrations were measured to obtain frequencies and amplitudes for ex-vivo testing. A piezoresistive accelerometer ligated to the maxillary right canines of 6 subjects transduced the intraoral vibrations. All subjects gave informed consent to participate. Amplitude and frequency of the vibrations were quantified and used in a bench-top friction testing apparatus. Active and passive ligation methods were compared for 9 vibration scenarios. The amount of time to move the bracket along a stainless steel wire was recorde...

Abstract Objective: To evaluate in vitro the influence of topical fluoride application on the mechanical properties of orthodontic cements containing fluoride under pH cycling conditions. Materials and Methods: Edgewise brackets for maxillary central incisors were bonded to 192 bovine incisors using Transbond XT (G1), Transbond Plus Color Change (G2), and Fuji Ortho LC (G3) (n ?=? 64 for each group). The specimens of each group were subdivided (n ?=? 16) into different subgroups. Subgroup A received no topical fluoride application during pH cycling, while the experimental subgroups received topical fluoride treatments as follows: B, application three times per day of fluoride dentifrice (1450 ppm F); C, application one time per day of fluoride mouth rinse (250 ppm F); and D, combination of fluoride dentifrice and fluoride mouth rinse. After 14 days of pH cycling, the shear bond strength and Adhesive Remnant Index were evaluated statistically. Results: Polarized light microscopy showed that pH cycling induced mineral loss in all specimens. The topical application of fluoride did not have an influence on shear bond strength, although the association of fluoride dentifrice and mouth rinse increased the shear bond strength of the resinous cement without fluoride (P fluoride treatments improved the shear bond strength of resinous cement, regardless of the material's fluoride-releasing capacity, and reached the adhesive fractures. PMID:22439766

Interdisciplinary cases can require orthodontic correction with implant anchorage prior to the placement of implant-supported restorations. Definitive implants for orthodontic anchorage offer several advantages compared to temporary attachment devices. Preorthodontic definitive implant placement requires accurate and detailed treatment planning to visualize the final orthodontic result and the optimal restoration position. This article describes a simplified method for creating a radiographic-surgical template for preorthodontic imaging and correct implant placement in the planned postorthodontic position. This approach uses common materials to combine the information from a preorthodontic diagnostic cast and the orthodontic setup/diagnostic wax-up/trial equilibration cast. PMID:22782051

An ideal all-ceramic restoration that conforms well and demonstrates enhanced biocompatibility, strength, fit, and esthetics has always been desirable in clinical dentistry. However, the inherent brittleness, low flexural strength, and fracture toughness of conventional glass and alumina ceramics have been the main obstacles for extensive use. The recent introduction of zirconia-based ceramics as a restorative dental material has generated considerable interest in the dental community, which has been expressed with extensive industrial, clinical, and research activity. Contemporary zirconia powder technology contributes to the fabrication of new biocompatible all-ceramic restorations with improved physical properties for a wide range of promising clinical applications. Especially with the development of computer-aided design (CAD)/computer-aided manufacturing (CAM) systems, high-strength zirconia frameworks can be viable for the fabrication of full and partial coverage crowns, fixed partial dentures, veneers, posts and/or cores, primary double crowns, implant abutments, and implants. Data from laboratory and clinical studies are promising regarding their performance and survival. However, clinical data are considered insufficient and the identified premature complications should guide future research. In addition, different zirconia-based dental auxiliary components (i.e., cutting burs and surgical drills, extra-coronal attachments and orthodontic brackets) can also be technologically feasible. This review aims to present and discuss zirconia manufacturing methods and their potential for successful clinical application in dentistry. PMID:20111760

The present study tested the shear bond strength (SBS) of orthodontic brackets bonded to teeth using flowable resins. A total of 105 human teeth were divided into seven groups. The brackets in each group were bonded to the tooth substrates using a Transbond XT adhesive and six other different flowable resins, respectively. Each adhesive resin was light-cured using a quartz-tungsten-halogen (QTH) light for 40 seconds. The brackets were debonded in shear mode using a universal testing machine. The brackets bonded using Tetric Flow and Grandio Flow showed slightly greater SBS values (13.0±1.8 and 12.2±1.2 MPa, respectively) than the Transbond XT adhesive (12.1±1.2 MPa). However, the SBS values of Transbond XT, X-flow, Tetric Flow, Grandio Flow, and Filtek Z350 flow were not significantly different. As for Admira Flow and Aelite Flow, they scored significantly lower SBS values (7.0±2.1 and 9.2±1.3 MPa, respectively) than the other groups. On bracket failure mode, statistical analysis revealed a similar failure mode among all the seven test groups.   

OBJECTIVE: To investigate the need and demand for orthodontic treatment of Chinese school children in Hong Kong. METHODS: The material consisted of study casts and questionnaires collected from 765 randomly selected 12-year-old school children in Hong Kong. The need for orthodontic treatment was ass...

The purpose of this study was to determine the method of preparation of enamel which best retains a bonded orthodontic bracket against a shear force. Two hundred and twelve human lower premolars were randomly divided into four equal groups. Group 1 underwent no air abrasion, group 2 received treatment with 25 microm aluminium oxide particles, group 3 with 50 microm particles, and group 4 with 100 microm particles. All groups were treated with a self-etching primer before bonding of an orthodontic bracket. Each tooth was tested in a JJ Lloyd M30K machine to determine the maximum shear force required to dislodge the bracket from the tooth. A one-way analysis of variance test conducted at a 95 percent confidence level (CL) demonstrated that there was a significant difference (P percent CL. There was no statistically significant difference between groups 1 and 2. There was, however, a statistically significant difference between groups 1 and 3 (P < 0.01), as well as between groups 1 and 4 (P < 0.01). In addition, there was significant difference found between groups 2 and 3 (P < 0.05), groups 2 and 4 (P < 0.01), and groups 3 and 4 (P < 0.05). PMID:19748923

Abstract in portuguese A montagem do aparelho fixo representa uma etapa importante da terapia ortodôntica, já que é através dos acessórios corretamente fixados aos dentes, e dos fios ligados a estes, que serão liberadas as forças armazenadas, resultando na movimentação dentária. Entretanto, não há unanimidade entre os autores quanto ao posicionamento vertical dos acessórios ortodônticos nos elementos dentários. Sendo assim, pretendeu-se com este trabalho revisar e discutir o assu (more) nto, bem como apresentar sugestões para a resolução das dificuldades clínicas inerentes à sua execução. A solução apresentada, que utiliza dados obtidos dos ensaios em modelos (setup), que são normalmente realizados como parte do planejamento do tratamento ortodôntico, fornecendo informações valiosas, que podem ser utilizadas para a correta montagem do aparelho. A utilização da sistemática apresentada mostrou-se extremamente válida e de comprovados resultados práticos. Abstract in english Bracket positioning is an important stage of orthodontic therapy because by the accessories correctly attached to teeth and the arch wires ties to them, teeth movement can take place by the force released from the orthodontic arch wires. Nevertheless, different authors suggest different bracket prescriptions with different vertical heights. Therefore, this study intended to make a review and discuss different vertical bracket prescriptions and suggest a procedure to overc (more) ome clinical difficulties that may occur on this process. The solution proposed that uses data obtained from setup performed in models casts, which usually are made as part of the orthodontic treatment planning, make up in valuable information that could be added for the correct appliance placement. This new procedure has showed extremely valid and of confirmed practical results.

The aim of this study was to evaluate the use of fluoride varnish as a prophylaxis method with self etching primer (SEP) and its comparison with pumice before orthodontic bonding. Thirty seven orthodontic patients participated in a prospective clinical trial. A split mouth technique was used in each patient, one quadrant was assigned to fluoride varnish and the contralateral quadrant to pumice prophylaxis. A total of 684 teeth were bonded with SEP (Transbond plus; 3M Unitek) and monitored for 6 months for bond failures. A total of 42 (6.1%) failures were recorded, 9 (2.6%) in the pumice group and 33 (9.6%) in the fluoride varnish group. Chi-square analysis was used to compare the number of bracket failures between the pumice and fluoride varnish groups and the number of patients in each gr...

Although the polymerization reaction in light-cured orthodontic adhesive continues for some time after light irradiation, it is unclear whether insufficiently irradiated adhesive develops sufficient bond strength. This in vitro study examined the maturation of bond strength after exposure of a variety of light doses. Large metal brackets were bonded to the enamel of 288 bovine mandibular incisors by irradiation at two light intensities (200 and 400 mW/cm2) and for three exposure times (3, 5, and 10 seconds) using three orthodontic adhesives (TB, OP, and BOB). Shear bond strengths and adhesive remnant indices (ARIs) were determined immediately (T1) and 24 hours after bonding (T2; n = 8 in each group). Comparisons were made using the Kruskal-Wallis H-test, the Bonferroni-corrected Mann-Whitn...

In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily doses, two elements of concern were nickel (573 vs. 15??g/l in the controls) and chromium (101 vs. 8??g/l in the controls). Three ion release coefficients were defined: ?...

Introduction Enamel decalcification is a common problem in orthodontics. The objectives of this randomized clinical study were to enumerate and compare plaque bacteria surrounding 2 bracket types, self-ligating (SL) vs elastomeric ligating (E), and to determine whether adenosine triphosphate (ATP)-driven bioluminescence could be used for rapid assessment of bacterial load in plaque. Methods Patients (ages, 11-17 years) were bonded with SL and E brackets in 14 maxillary and 12 mandibular arches by using a split-mouth design. Recall visits were at 1 week and 5 weeks after bonding. Plaque specimens were assayed for oral bacteria and subjected to ATP-driven bioluminescence determinations with a luciferin-based assay. Results In most patients, teeth bonded with SL attachments had fewer bacteria...

This study compared the moments produced by V-bends placed in rectangular nickel titanium (NiTi) orthodontic wire to those produced in titanium-molybdenum alloy (TMA). V-bends that included angles of 135, 150, and 165 degrees were heat set into 0.017 x 0.025 and 0.016 x 0.025 inch NiTi alloy wires and identical bends bent into TMA wires with a dimension of 0.018 x 0.025 and 0.016 x 0.022 inch. There were five specimens per group (N = 60). The moments produced by each specimen were tested on a custom jig that aligned two lower incisor brackets with zero tip or torque at an interbracket distance of 15 mm. The upper bracket was connected to a moment transducer. The V-bend position for each specimen was varied in 1 mm increments towards the moment transducer. The moments produced by TMA wires ...

The double J retractor (DJR) is a novel method to close extraction space with the aid of mini-implants. DJR is placed lingually on the incisors and has a lower profile compared with the conventional lingual bracket appliance. It consists of a newly designed lingual level arm retractor connected to the lingual of the 6 splinted anterior teeth. The anterior segment is retracted with a mini-anchor-screw as a temporary skeletal anchorage device without brackets and wires on the posterior teeth. Compared with conventional orthodontic procedures, such as leveling, space closure, and finishing, the procedures used with DJR are reduced to 2 steps: space closure and alignment/finishing. With DJR, the anterior teeth are retraced first without the leveling stages, and then the leveling and finishing ...

The purpose of this study was to evaluate enamel colour alteration of five different orthodontic bonding adhesives by means of digital measurements after exposure to photoageing in order to simulate discolouration of adhesives in vivo. Seventy-five non-carious premolars were randomly divided into five equal groups. The brackets were bonded with five different adhesives (Transbond XT, Eagle Bond, Light Bond, Blugloo, Unite) and subjected to artificial accelerated photoageing for 24 hours. The enamel surfaces were colourimetrically evaluated before bonding, following debonding and cleaning with a tungsten carbide bur, after polishing with Stainbuster, and after photoageing of the debonded enamel surface. The Commission Internationale de l'Eclairage(CIE) colour parameters (Lab) were recorded ...

Abstract in portuguese O objetivo deste estudo foi analisar as metodologias empregadas em testes in vitro de força de adesão em Ortodontia. Foram selecionados nos periódicos American Journal of Orthodontics and Dentofacial Orthopedics e The Angle Orthodontist (do ano de 1993 até 2002) todos os artigos onde foi avaliada a resistência de adesão de braquetes a diferentes superfícies, através de Máquinas de Ensaio Universal Instron ou similares. Foram analisados 127 artigos, e destes 86% f (more) oram conduzidos através de ensaios de cisalhamento, ao passo que 14% foram através de ensaios de tração. Dentre os estudos com dentes humanos (68%), os pré-molares foram os mais utilizados (57%), seguidos pelos molares (31%). Quanto ao número de espécimes por grupo, 28 estudos analisaram entre 6 e 10; 30 entre 11 e 15; 33 entre 16 e 20; e 36 analisaram mais de 20 espécimes. Como solução de armazenamento, as mais empregadas foram: água destilada (43%), seguido por Timol a 0,1% (28%) e Cloreto de sódio a 0,9% (12%). No que diz respeito à velocidade de operação da máquina, em 25 estudos foi de 0,5 mm/min; em 43 foi de 1,0mm/min; em 8 foi de 2,0 mm/min; e em 38 foi de 5,0 mm/min. Os autores concluem que não existe um consenso na metodologia de tais estudos, sendo então evidenciada a necessidade de uma possível padronização da técnica. Abstract in english The aim of this study was to examine the recent methodology used in laboratory analysis of bond strength in orthodontics. The material used was all the articles published in the American Journal of Orthodontics and Dentofacial Orthopaedics or The Angle Orthodontics in which the bonding between the bracket and several surfaces were evaluated by Instron Universal Testing Machine or similar devices. It was found 127 articles, in which 86% tested the specimens in shear mode, (more) and 14% used the tensile technique. Among the studies with human teeth (68%) premolars were the most frequent (57%), followed by molars (31%). According to the number of specimens per group, 28 studies analysed from 6 to 10; 30 from 11 to 15; 33 from 16 to 20; and 36 analyzed more than 20 specimens. According to nature of the storage solution, the most used were distilled water (43%), followed by 0.1% Timol (28%) and 0.9% saline solution (12%). With regard to the cross head speed, in 25 studies were of 0,5mm/min; in 43 were of 1.0mm/min; in 8 was of 2.0mm/min; and in 38 was of 5.0mm/min. The authors concluded that there was not an agreement in the methodology on those studies, and so there is a potential need of technique standardization.

Abstract Background: It is clinically challenging to place and restore an implant when the mesio-distal space is limited or reduced at the occlusal plane and/or the bone level. Placing implants in these cases while ignoring the clinical difficulties and compromising treatment could limit the successful outcome. Treatment options include strategic extractions, sectional orthodontics, and minor orthodontic movements. Purpose: To discuss the clinical problems and difficulties arising from limited edentulous mesio-distal space interdentally and to present a treatment modality and technique. Materials and Methods: Orthodontic elastic separating rings are used to open interdental space between teeth and implants, exerting forces against implants for regaining the needed space and restoring impla...

AIM: Approach to dental trauma should always be based on a careful examination of the traumatised area, including both hard and soft tissues, to ascertain the presence of a foreign body and to assess the best treatment and follow-up. In this work a case of an orthodontic bracket migrated to the upper lip and retained there for 10 years, following a trauma is discussed. CASE REPORT: The patient complained symptomatic swelling of the upper lip; palpation and x-rays showed the presence of a foreign body, identified as an orthodontic bracket. Medical history revealed that patient had a dental trauma 10 years prior. The foreign body was localised and removed. At the two week follow-up visit after surgical incision of the lip, signs and symptoms (i.e. the swollen lip) were resolved. This case emphasises the importance of accurate management of the traumatic event, through proper diagnosis and therapy of both hard and soft tissues, even if the examination if the patient is performed years after the dental trauma. PMID:22971264

This study evaluated the shear bond strength (SBS) of a traditional orthodontic bracket bonding agent (Transbond XT) against two self-etch, self-adhesive systems (Maxcem Elite and Vertise Flow). Sixty premolar teeth and sixty brackets were randomly and equally divided into five groups: Transbond XT (TXT) as the control, Maxcem Elite (ME) without etching, ME with etching (ME/ Etch), Vertise Flow (VF) without etching, and VF with etching (VF/Etch). Respective SBS results of the five groups were 9.86±3.20, 4.67±2.94, 7.82±2.56, 2.55±0.77, and 7.89±1.17 MPa. SBS values of the new self-etch adhesive systems were significantly lower than the traditional etch-and-rinse control (p<0.005). However, no significant differences were found between TXT and the self-adhesives applied with etching (p>0.005). After debonding, ARI scores “0" and “1" were predominant in non-etched ME and VF groups. It was concluded that new self-etch, self-adhesive bonding systems require additional phosphoric acid application to achieve comparable SBS values as the traditional orthodontic bonding agent.   

One of the most important applications of shape memory alloy is in medicine, especially orthodontic archwires. In this category Ni-Ti orthodontic archwires is one of the oldest used materials. Biocompatibility, corrosion resistance, super elasticity, etc. are its outstanding properties. In spite of the importance of dependency of pre-strain on microstructure of Ni-Ti there are limited sources concentrated on the subject. For this reason the main purpose of the current study is determination of the effect of pre-strain on microstructure of Ni-Ti orthodontic archwires. In this regard, three-point bending was performed on the orthodontic archwire specimens to apply different amount of strain. The microstructures were compared with the un-strained wire using optical and scanning electron microscopes. The results showed that the stable phase depends strongly on the value of pre-strain. Increasing pre-strain causes to decrease martensite laths and leads the microstructure toward austenite phase.

Abstract in portuguese Atualmente, os braquetes autoligáveis têm sido associados a tratamentos mais rápidos e eficazes, o que desperta a curiosidade em compará-los ao sistema convencional. Ao contrário dos braquetes tradicionais, os autoligáveis não necessitam de ligaduras, sejam elásticas ou metálicas. A literatura é farta em concluir que essa característica diminui, ostensivamente, a resistência do atrito durante as mecânicas de deslize. Além disso, existem alegações sobre a d (more) imimuição da necessidade de extrações e de expansão maxilar com o uso desses acessórios. Portanto, o objetivo dessa revisão de literatura foi buscar os mais novos estudos a respeito dos aparelhos autoligáveis atualmente utilizados nos tratamentos ortodônticos, confirmando ou retificando as especulações vigentes. Abstract in english Currently self-ligating brackets have been associated to faster and more efficient treatments, which arouse the curiosity to compare them to the conventional system. Unlike traditional appliances, self-ligating brackets do not require elastomeric or metal ligatures. The literature is abundant in concluding that this feature decreases, ostensibly, the friction resistance during the sliding mechanics. Moreover, there are reports on minimizing the need of extractions and max (more) illary expansion using these accessories. Therefore, the purpose of this literature review was to seek the newest studies about the self-ligating brackets currently used in orthodontic treatments, confirming or correcting current speculations.

Objectives: To compare the sliding resistance forces produced by polycarbonate self-ligating brackets with esthetic archwires. Materials and methods: Samples of Opal, Oyster and conventional Blonde brackets were tested each one with 30 segments of .018x.025-in wires. The archwires were slipped at 8mm/min for 40seconds with an universal testing machine. Two way ANOVA with Bonferroni correction were used. Results: Blonde brackets presented the highest sliding resistance, followed in decreasing order by Oyster and Opal. The TP Shiny Bright Wire produced the highest surface friction, while the lowest was observed for Imagination archwires (except for Opal brackets where the TP Pearltone Wire achieved the best performance). Conclusions: Self-ligating system is more effective to reduce the slidi...

The widespread use of indwelling medical devices has enormously increased the interest in materials incorporating antibiotics and antimicrobial agents as a means to prevent dangerous device-related infections. Recently, chlorhexidine-loaded polyurethane has been proposed as a material suitable for the production of devices which are able to resist microbial contamination. The aim of the present study was to characterize the in vitro release of chlorhexidine from new polymeric orthodontic chains realized with polyurethane loaded with two different chlorhexidine salts: chlorhexidine diacetate or chlorhexidine digluconate. The orthodontic chains constituted of three layers: a middle polyurethane layer loaded with chlorhexidine salt inserted between two layers of unloaded polymer. In vitro release of chlorhexidine diacetate and digluconate from orthodontic chains loaded with 10% or 20% (w/w) chlorhexidine salt was sustained for 42 days and followed Fickian diffusion. The drug diffusion through the polyurethane was found to be dependent not only on chlorhexidine loading, but also on the type of chlorhexidine salt. The antibacterial activity of 0.2% (w/w) chlorhexidine diacetate-loaded orthodontic chain was successfully tested towards clinically isolated biofilm forming ica-positive Staphylococcus epidermidis via agar diffusion test. In conclusion, the chlorhexidine salt-loaded chains could provide an innovative approach in the prevention of oral infections related to the use of orthodontic devices. PMID:23090109

Objective: The purpose of this pilot study was to evaluate the remineralisation of eroded enamel by NaF rinses in an intra-oral model. Methods: Serving as their own control, subjects (N=80) participated in a randomised, four-leg (20 subjects/leg), 28-day, parallel design study. In each leg, each participant wore a customised orthodontic bracket attached to a mandibular molar that contained one tooth block having an initial erosive lesion (0.3% citric acid, pH 3.75, 2h). Within the 28-day period, participants engaged in twice-daily brushing for 1min with a fluoride-free dentifrice followed by 1-min rinsing with one of the following aqueous rinses: fluoride-free (0ppm F), 225ppm F, 225ppm F plus functionalised @b-tricalcium phosphate (fTCP), and 450ppm F. Following intra-oral exposure, appli...

Abstract in english Nickel-free braces have gained popularity as a viable alternative for patients who are allergic to nickel. The purpose of this systematic review was to determine whether evidence exists to justify the use of nickel-free brackets in orthodontic patients who are allergic to nickel. An electronic search was performed using 7 databases (MEDLINE, BBO, LILACS, Web of Science, EMBASE, BIREME and Cochrane Library), without restriction regarding year or language, with supplemental (more) manual searching of the references of retrieved articles. The search strategy produced 89 papers. The data extraction and quality score of each paper were evaluated independently by two reviewers, once each. After selection based on the eligibility criteria, four papers, including 2 controlled clinical trials and 2 clinical trials, qualified for the final analysis. Quality assessment of the included articles was also performed. Nickel-free braces (Ni content - 2% max.) seem to represent a viable alternative for orthodontic patients who are allergic to nickel. However, further in vivo studies, considering the immunology characteristics of patients, are needed to determine the clinical implications of the findings of this study.

The purpose of this study was to evaluate enamel colour alteration of five different orthodontic bonding adhesives by means of digital measurements after exposure to photoageing in order to simulate discolouration of adhesives in vivo. Seventy-five non-carious premolars were randomly divided into five equal groups. The brackets were bonded with five different adhesives (Transbond XT, Eagle Bond, Light Bond, Blugloo, Unite) and subjected to artificial accelerated photoageing for 24 hours. The enamel surfaces were colourimetrically evaluated before bonding, following debonding and cleaning with a tungsten carbide bur, after polishing with Stainbuster, and after photoageing of the debonded enamel surface. The Commission Internationale de l'Eclairage(CIE) colour parameters (L*a*b*) were recorded and colour differences (DeltaE) were calculated. The results were statistically analyzed using the Kruskall-Wallis test. Further investigation among subgroups was performed using Dunn's multiple correlation test (P < 0.05). The clinical detection threshold for DeltaE value was set at 3.7 units. DeltaE values between the first and second measurements showed an increase in the Transbond XT, Eagle Bond, and Light Bond groups. The highest DeltaE value was 1.51 +/- 1.15 in the Transbond XT group. No clinically significant DeltaE value was observed. Colour changes of orthodontic bonding systems induced by photoageing cannot be clinically observed. Polishing with Stainbuster eliminates enamel surface roughness, which may improve light reflection. PMID:19460855

This study examined the effect of ligation on the load-deflection characteristics of nickel-titanium (NiTi) orthodontic wire. A modified three-point bending system was used for bending the NiTi round wire, which was inserted and ligated in the slots of three brackets, one of which was bonded to each of the three bender rods. Three different ligation methods, stainless steel ligature (SSL), slot lid (SL), and elastomeric ligature (EL), were employed, as well as a control with neither bracket nor ligation (NBL). The tests were repeated five times under each condition. Comparisons were made of load-deflection curve, load at maximum deflection of 2,000 microm, and load at a deflection of 1,500 microm during unloading. Analysis of Variance (ANOVA) and Dunnett's test were conducted to determine method difference (alpha = 0.05). The interaction between deflection and ligation was tested, using repeated-measures ANOVA (alpha = 0.05). The load values of the ligation groups were two to three times greater than the NBL group at a deflection of 1,500 microm during unloading: 4.37 N for EL, 3.90 N for SSL, 3.02 N for SL, and 1.49 N for NBL (P superelasticity with SL, whereas EL may act as a restraint on its superelasticity. PMID:17873145

Abstract in portuguese Este trabalho teve como objetivo avaliar a capacidade alergênica provocada pelos bráquetes ortodônticos, comparando a sensibilidade cutânea provocada pelos metais presentes nos bráquetes metálicos convencionais com a provocada por bráquetes com baixa concentração de níquel ("nickel-free"). A amostra foi selecionada dos 400 pacientes em tratamento da clínica de Ortodontia da Pontifícia Universidade Católica de Minas Gerais (Belo Horizonte, MG, Brasil), no per? (more) ?odo compreendido entre o início de 2002 e o final de 2003. A amostra consistiu de 58 pacientes (30 homens e 28 mulheres), com idades variando de 11 a 30 anos, os quais eram portadores de aparelho ortodôntico fixo Morelli® em ambos os arcos. Estes pacientes foram diagnosticados quanto à sensibilidade ao níquel, por meio da aplicação do "patch test" com sulfato de níquel a 5%. Em uma segunda fase, trinta dias após o "patch test", comparou-se a sensibilidade cutânea provocada pelos metais presentes nos bráquetes convencionais e nos "Nickel Free", por meio de um teste de sensibilidade cutânea utilizando-se dois tipos de corpos-de-provas, em formato de disco, com a mesma composição destes bráquetes. A área de eleição para realização deste teste foi a parte interna do antebraço, sendo aplicados vinte corpos-de-prova de cada experimento (referente a uma boca completa de bráquetes). Dos 58 pacientes avaliados, 16 deles foram sensíveis ao "patch test" com sulfato de níquel a 5%. Dentre estes 16 pacientes, 12 deles desenvolveram reação alérgica ao Experimento 1 (corpo-de-prova com níquel), enquanto que no Experimento 2 (corpo-de-prova "Niquel Free") apenas 5 pacientes apresentaram sensibilidade a esta amostra. O teste de McNemar revelou que os corpos-de-prova "nickel-free" provocaram menor reação alérgica quando comparados aos convencionais (p = 0.016). Abstract in english The aim of this study was to evaluate the allergenic potential of orthodontic brackets, comparing the cutaneous sensitivity provoked by metals present in conventional metallic brackets to that provoked by brackets with a low concentration of nickel, known as "nickel-free". A sample was selected from 400 patients undergoing treatment in the orthodontic clinic of the Pontifical Catholic University of Minas Gerais (Belo Horizonte, MG, Brazil), in the period from the beginnin (more) g of 2002 to the end of 2003. A cutaneous sensitivity patch test containing 5% nickel sulphate was used in 58 patients (30 males and 28 females), aged between 11 and 30, which were using fixed appliances with Morelli® brackets in both arches. In a second phase, 30 days later, a comparative test of cutaneous sensitivity was applied to the whole sample with two types of test specimens, in the form of a disc. Two alloys were tested: discs composed of the alloy used in the construction of conventional brackets and discs composed of a nickel-free alloy. The internal part of the forearm was chosen for testing, and 20 test specimens of each experiment (corresponding to the twenty brackets of a complete fixed appliance) were applied. Of the 58 patients evaluated, 16 patients were sensitive to the patch test with 5% nickel sulphate. Out of these 16 patients, 12 developed an allergic reaction to experiment 1 (test specimen with nickel), while in experiment 2, only 5 patients showed sensitivity to that sample. The McNemar test revealed that the nickel-free test specimens provoked less allergic reaction when compared with the conventional alloy (p = 0.016).

Abstract Objective. To compare the effects on enamel demineralization and fluoride (F) retention of two different brushing-rinsing regimens. Material and methods. An in-situ caries model with orthodontic bands was used for 8-9 weeks. A total of 20 orthodontic patients participated. They were randomized into two groups: (1) a test group using 5000 ppm F (n = 10) with no post-brushing water rinsing; and (2) a control group using 1450 ppm F (n = 10) with three sessions of post-brushing water rinsing. Orthodontic stainless-steel bands were applied to the two upper first premolars, leaving 2-3 mm of space away from the exposed buccal surface in order to accumulate plaque and provoke initial caries development. The teeth were extracted after 8 and 9 weeks, then analysed using quantitative light-...

The aims of this in vitro study were to quantify the effect of manual versus automatic mixing and of using a disinfectant on mechanical properties of three different alginate impression materials. Two of the three alginates tested were especially developed for orthodontic use: Orthotrace and Orthofi...

Abstract in spanish Fundamento: los tratamientos ortodóncicos con aparatos fijos proporcionan un ambiente adecuado para el desarrollo de la placa dentobacteriana, en bandas, brackets, alambres, aumentando considerablemente el riesgo de aparición de la caries dental en estos pacientes.Objetivo: determinar los factores de riesgo a caries en pacientes con aparatos ortodóncicos fijos. Método: se realizó un estudio descriptivo en la consulta de ortodoncia de la clínica estomatológica del H (more) ospital Militar de Camagüey, desde de octubre de 2007 hasta mayo de 2008. El universo de estudio estuvo constituido por ciento veintinueve pacientes, la muestra quedó conformada por cuarenta y siete, escogidos por muestreo simple aleatorio, por el programa Sigesmu que cumplieron los criterios de inclusión. Los factores de riesgo se identificaron a través del interrogatorio y del examen clínico bucal, plasmándose los datos en un formulario confeccionado al efecto. Los datos obtenidos se procesaron mediante el sistema estadístico SPSS/PC 11.1 utilizándose estadística descriptiva e inferencial. Resultados: los factores de riesgo predominaron de forma significativa, el 100% de los pacientes presentaron herencia de caries, la mala higiene bucal se encontró en el 76,5%, seguida de la dieta cariogénica y el apiñamiento dentario. Conclusiones: los factores de riesgo de caries resultaron significativos en el grupo de estudio. El antecedente de caries y el apiñamiento dentario prevalecieron significativamente en las edades de 14 a 19 años y en el sexo masculino la mala higiene bucal. Abstract in english Background: orthodontic treatments with fixed appliance provide an appropriate atmosphere for the development of dentobacterial plaque, in bands, brackets, wires, increasing considerably the risk of appearance of dental caries in these patients. Objective: to determine the risk factors to caries in patients with fixed orthodontic appliance. Method: a descriptive study in the orthodontics consultation at the Odontology clinic of the Military Hospital of Camagüey was perfo (more) rmed, from October 2007 to May 2008. The universe was constituted by one-hundred twenty-nine patients; the sample remained conformed by forty-seven patients, chosen by simple random sampling, using the Sigesmu program that fulfilled the inclusion criteria. The risk factors were identified through interrogation and the oral clinical examination; data were stored in a form made to the effect. The obtained data were processed by means of the SPSS/PC 11.1 statistical system making use of inferential descriptive statistics. Results: risk factors prevailed in a significant way, the 100% of patients presented caries inheritance, bad oral hygiene was in 76,5%, followed by the cariogenic diet and dental crowding. Conclusions: risk factors of caries were significant in the study group. Caries antecedent and dental crowding prevailed significantly in the ages from fourteen to nineteen years, and bad oral hygiene in the masculine sex.

The four connections for the control dewar and VLPC bayonet can platform are designed, using finite element analysis, to carry all dead weight and live loads. Based on the loads applied to the platform, two 1 inch thick plates and two 3/4 inch thick brackets made of ASTM A572-Grade 42 are required. The 1 inch thick plate requires a 3/8 inch thick intermediate steel material, between the 8-inch x 4-inch x 1/4-inch boom and the plate, for load reinforcement as well as weld area reinforcement. Both the plates and the brackets require 3/4 inch steel bolt connections.

Shape memory and superelasticity are novel properties not exhibited by common materials. In recent years, these properties and the alloys exhibiting them have found widespread use as new medical materials, in devices such as diagnostic and therapeutic catheters of different kinds, stents, needle wire localisers, orthodontic arch wires, implantable drug delivery system etc. The reasons for this trend and the future potential of these materials in medical applications will be explained in this presentation. PMID:9830988

Clarifying the genetic factors involved in maxillofacial growth and development is very important in orthodontic treatment planning and prognosis. However, few dental studies have examined multiple births. The present orthodontic evaluation was conducted using orthodontic data from a set of quadruplets. Orthodontic evaluation was performed on a set of quadruplets (1 girl and 3 boys) aged 9 years and 7 months at the initial visit. Although all 4 children weighed only about 1,400 g each at birth, height and body weight subsequently normalized. Mean skeletal age of the quadruplets was 10 years and 2 months, about 6 months ahead of their calendar age. In all 4 children, facial profile was mostly symmetrical and convex. Intraoral findings showed a Hellman's dental age of IIIA, together with spacing of the upper anterior teeth. Both overbite and overjet were 5-7 mm, and mesial step of the terminal plane was noted. Model analysis showed that tooth materials were on the large side, while arch width was narrow. Cephalometric analysis revealed that the ANB of the first- and fourth-born children was 6°, and skeletal maxillary protrusion due to mandibular retrusion was diagnosed. The second- and thirdborn children exhibited no marked skeletal abnormalities.   

Abstract in english The objective of this study was to compare the effectiveness of two manual toothbrushes (conventional and orthodontic). The following clinical parameters were used: VPI (visible plaque index) and GBI (gingival bleeding index). Patients, 64 total (30 males and 34 females), in the permanent dentition, with a mean age of 17.8 years, were randomly selected from a practice specializing in orthodontics. Each participant received audio-visual instructions on oral hygiene as well (more) as a kit of materials containing two manual toothbrushes (orthodontic and conventional). Each toothbrush was randomly allocated to one side of the mouth (split-mouth design) and used for a period of approximately 4 weeks. The VPI and GBI were measured by a single calibrated examiner before (T0) and after (T1) the implementation of interventions. The Mann-Whitney test was used to compare the VPI values between the groups, and the Student t-test for independent samples was used to compare GBI values. The level of significance was set at 5%. No statistically significant difference was observed between the groups at T0 for both VPI and GBI, and at T1 for the GBI. The manual orthodontic toothbrush produced a statistically lower VPI (P

The device has a bracket so it can be joined with stoping machinery; a drum with material sold in rolls which is placed on a shaft; and a mechanism for lacing the drum material, which contains a two-armed lever. The lever it set so it can interact on one end with the material sold in rolls. To ensure removal of this material from the turning mass and to increase safety, a wheel is placed on the shaft of the drum. The shaft has a spring-opposed fork end joined with a hinge to the bracket using the shaft and the spring. The two-armed level has rollers at the ends. The other end of the 2-armed lever is made so it can interact with the wheel.

Abstract in english Since the 1980s, different devices based on superelastic alloys have been developed to fulfill orthodontic applications. Particularly in the last decades several researches have been carried out to evaluate the mechanical behavior of Ni-Ti alloys, including their tensile, torsion and fatigue properties. However, studies regarding the dependence of elastic properties on residence time of Ni-Ti wires in the oral cavity are scarce. Such approach is essential since metallic a (more) lloys are submitted to mechanical stresses during orthodontic treatment as well as pH and temperature fluctuations. The goal of the present contribution is to provide elastic stress-strain results to guide the orthodontic choice between martensitic thermal activated and austenitic superelastic Ni-Ti alloys. From the point of view of an orthodontist, the selection of appropriate materials and the correct maintenance of the orthodontic apparatus are essential needs during clinical treatment. The present work evaluated the elastic behavior of Ni-Ti alloy wires with diameters varying from 0.014 to 0.020 inches, submitted to hysteresis tensile tests with 8% strain. Tensile tests were performed after periods of use of 1, 2 and 3 months in the oral cavity of patients submitted to orthodontic treatment. The results from the hysteresis tests allowed to exam the strain range covered by isostress lines upon loading and unloading, as well as the residual strain after unloading for both superelastic and thermal activated Ni-Ti wires. Superelastic Ni-Ti wires exhibited higher load isostress values compared to thermal activated wires. It was found that such differences in the load isostress values can increase with increasing residence time.

Abstract Objective: The quality and quantity of the alveolar process are considered important influential factors affecting the anchorage effectiveness of orthodontic mini-implants. The objective of this study was to establish the effect of various material parameters in regard to various implant types, sizes, and load directions using the finite element method (FEM). Materials and Methods: FE models of the following 16 implants by six different manufacturers were made in idealized jaw bone segments with the program system MSC.Marc/Mentat: ?arhus Mini-Implant (American Orthodontics), AbsoAnchor? (Dentos), Dual-Top? (Jeil Medical), LOMAS (Mondeal), OrthoImplant (IMTEC), tomas ? (Dentaurum). The intra-osseous parts of the mini-implants had lengths ranging between 6.7 mm and 10.0 mm, and diam...

Abstract in english INTRODUCTION: Although several studies have discussed nickel influence on the development of immunological reactions in orthodontic patients, it is noticed that the evidence towards the appliances, as well as towards the possible consequences of this material on the oral and general health of the individual are still inconsistent. OBJECTIVE: The aim of this article is to present the current stage of knowledge on this issue, highlighting the most recent findings considering the periodontal and humoral aspects of allergic subjects.

Abstract in portuguese O objetivo do presente estudo foi avaliar in vitro o efeito preventivo a cárie de resinas ortodônticas fluoretadas submetidas à ciclagem de pH utilizando dois tipos de saliva desmineralizadora. Bráquetes de incisivos centrais foram colados em 60 incisivos bovinos, utilizando a resina ortodôntica Transbond Plus Color Change (n=30) ou Fill Magic (n=30). Cada grupo foi dividido em 3 subgrupos (n=10): imersão em saliva artificial remineralizante por 14 dias e simulaçã (more) o de alto desafio cariogênico com ciclagem de pH em saliva ácida com pH 5,5 ou pH 4,5. Após 14 dias de ciclagem de pH, o efeito preventivo de cárie foi avaliado por meio da formação de halo de inibição da mancha branca, adotando-se os escores: 0-ausência e 1-presença. Os testes Kruskal Wallis e Man-Whitney (a=0,05) foram aplicados. A formação de lesões de mancha branca foi observada somente na ciclagem de pH com saliva ácida a pH 4,5; sendo o Transbond Plus Color Change significantemente mais efetivo na prevenção ao desenvolvimento de mancha branca quando comparados ao Fill Magic (p Abstract in english The aim of the present study was to evaluate the in vitro caries preventive effect of fluoridated orthodontic resins under pH cycling with two types of acid demineralizing saliva. Brackets were bonded to 60 bovine incisors, using either Transbond Plus Color Change (n=30) or Orthodontic Fill Magic (n=30) orthodontic resins. Each group of resin was divided into 3 subgroups (n=10): immersion in remineralizing artificial saliva for 14 days, pH cycling with high cariogenic cha (more) llenge in acid saliva with pH 5.5, and acid saliva with pH 4.5. After 14 days of pH cycling, the caries preventive effect on the development of white spot lesion was evaluated considering the presence of inhibition zones to white spot lesions using two scores: 0= absence and 1= presence. Kruskal Wallis and Mann-Whitney tests (a=0.05) were used. Formation of white spot lesions was observed only under pH cycling using acid saliva with pH 4.5; with Transbond Plus Color Change being significantly more effective (p

Miranda J, Brunet Ll, Roset P, Farré M, Mendieta C. Reliability of two measurement indices for gingival enlargement. J Periodont Res 2012; 47: 776-782. © 2012 John Wiley & Sons A/S Background and Objective:? The objective of this study was to analyze the concordance of the vertical gingival overgrowth index (GOi) and the horizontal Miranda & Brunet index (MBi) and to compare their reliability and reproducibility for an early diagnosis of gingival enlargement. A wide range of methods has been employed to determine the severity of drug-induced gingival enlargement (DIGE) that has resulted in uncertainty with regard to the prevalence of this side effect. In recent studies, different indices have been used to grade DIGE. The large variability observed between studies and the differences between vertical and horizontal gingival-enlargement measurements could be the result of the use of nonreliable indices during the measurement process. Some indices involve invasive procedures that require many measurements, or even a data-processing system, while others are less convenient and technically expensive and complex. In previous studies we used two complementary indices - the vertical GOi and the horizontal MBi. The results of these studies found some differences between both indices, with the MBi rendering higher estimates of DIGE prevalence that was attributed to its greater sensitivity for the detection of minimal changes in gingival thickness. To our knowledge, there are no studies comparing different measurement indices for gingival enlargement that are supported by statistical concordance analysis. Material and Methods:? Twelve plaster casts from patients who had worn orthodontic brackets, and who had different degrees of chronic inflammatory gingival enlargement, were analyzed. Three previously trained examiners registered twice the degree of buccal overgrowth, using the GOi and MBi, in all cast models with a minimum interval of 7?d between the first and the second evaluation. In total, from each cast, measurements from 16 gingival sites were taken using the GOi, and from nine gingival units (mesial and distal sites measurements) using the MBi. Concordance analysis of the registered measurements (intra-examiner and among examiners) for each index and between indices was assessed using the nonweighted Kappa index with a confidence interval of 95%. Results:? We obtained 648 values for the GOi and the MBi. The overall score 0 (indicating absence of enlargement) was 32.7% and 19.8% for GOi and MBi, respectively, score 1 (light/moderate) was 39.7% and 48.1%, and score 2 (severe) was 27.6% and 32.1%. Concordance analysis for each index showed intra-examiner Kappa values of 0.820 for the GOi and 0.830 for the MBi. Interexaminer Kappa values were 0.720 for the GOi and 0.770 for the MBi. Concordance between indices showed Kappa values for the same examiner of 0.600, whereas concordance among different examiners was 0.550. Discrepancies between indices indicated a systematic skew, with 79-82.1% of discrepancy associated with a higher value for the MBi compared with the GOi. Conclusion:? Both gingival enlargement indices analyzed are reliable, complementary and applicable for measuring gingival overgrowth. However, the MBi shows, with fewer measurements, a greater sensitivity than the GOi for the detection of the early stages of gingival enlargement, being adequate for the screening of large populations at risk. PMID:22897219

Abstract Aim: The aim of this article is to describe a technique to fabricate a spring retained surgical obturator prosthesis for rehabilitation of a patient with total maxillectomy. Material and Methods: The mandibular retention plate was fabricated with the help of hard, round, stainless steel orthodontic wires and heat-polymerizing acrylic resin. The 0.6 mm wire is manipulated to make Adams clasps on right and left mandibular first molars and 1 mm wire to make C clasps on right and left mandibular first premolars. A palatal shaped maxillary obturator plate was fabricated with acrylic resin. Two newly designed springs were fabricated with 0.6 mm orthodontic wire. Lower end of the springs were attached to the mandibular retention plate and upper ends were attached to the maxillary obturat...

Abstract Objectives: The objectives of this animal study were to evaluate if orthodontic loading has an impact on osseointegration of screws supporting miniplates, and to describe the histological components of the bone-screw interface. Materials and methods: Eighty orthodontic miniplates were placed in the jaws of 10 dogs. After 2 weeks, a 125 g force was applied between the miniplates of one upper quadrant of each dog and between those of the controlateral lower quadrant. The others, nonloaded miniplates, were considered as controls. Five dogs were sacrificed 7 weeks after implantation and the remaining five dogs after 29 weeks [Short Term (ST) and Long Term (LT) groups, respectively]. Fluorochromes were injected at implantation and at sacrifice. Jaw quadrants were dissected, embedded, c...

Oral Diseases (2011) 17, 489-498 Objective:- The aim of this study was to investigate how interleukin (IL)-8 (cytokine-induced neutrophil chemoattractant; CINC-1) and monocyte chemotactic protein (MCP)-1/CCL2 contribute to root resorption during orthodontic tooth movement. Materials and methods:- Forty 6-week-old male Wistar rats were subjected to orthodontic force of 10 or 50-g to induce a mesially tipping movement of the upper first molars for 7-days. We determined the expressions of CINC-1, CXCR2, and MCP-1 proteins in root resorption area using immunohistochemistry. Furthermore, we investigated the effects of compression forces (CF) on IL-8 and MCP-1 production by human periodontal ligament (hPDL) cells. We observed an effect of chemokine treatment on rat odonto/osteoclasts in dentin s...

Abstract Objective: The purpose of this study was to compare the speed of the orthodontic tooth movement of rat molars under continuous wave (CW) and pulsed wave (PW) low-level laser therapy (LLLT). Background data: It remains unclear whether LLLT can increase the speed of tooth movement, and no consensus has been established regarding the appropriate parameters and experimental design of LLLT. Materials and methods: Orthodontic movement was induced in 40 rats with 10g coil springs. Rats were randomly assigned to five groups. In Group I, the maxillary left first molars were irradiated with CW by a gallium aluminum arsenide (GaAlAs) diode laser source (830?nm, 180?mW, 3.6?J/cm2, and 0.9?W/cm2 for 4?sec at three locations for 3 consecutive days). In Groups II, III, and IV, animals were irrad...

Several researches have been demonstrating an increase in the resistance acid of the enamel surface when irradiated by some lasers types as Nd:YAG, C0{sub 2}, Er:YAG, and others, mainly when combined with the fluoride therapy after the irradiation of the laser. This study in vitro used the laser of Er:YAG which density of energy of 8.1 J/cm{sup 2} on the enamel about of orthodontical brackets of teeth extracted pre-molars. These teeth were then submitted to a rich way in S. mutans for twenty one days. The cases were analyzed: (1) enamel surface without any treatment, (2) enamel surface without any irradiation laser, but with therapy with acidulated phosphate fluoride, (3) enamel surface irradiated with laser of Er:YAG and (4) enamel surface irradiated by laser of Er:YAG and with application of acidulated phosphate fluoride. The results were analyzed through optical microscopy and scanning electron microscopy. The morphologic changes observed to the scanning electron microscopy suggest increase in the acid resistance of the enamel surface. However, to the optical microscopy, it was still possible to visualize undesirable white stains in the surface of the enamel. (author)

This paper presents a non-linear finite element analyses in order to optimize the seismic characteristics of strap-braced cold formed steel shear walls enhanced with brackets in the four interior corners of the wall. The numerical models presented here are verified based on experimental tests considering different structural characteristics including: material nonlinearity, geometrical imperfection, residual stresses and perforations. A comparison between the numerical simulations and the test results shows a good agreement proves that the finite element analysis can be used effectively to predict the ultimate capacity of strap-braced CFS shear panels. A total of 16 models with different variants of bracket length are investigated. Of particular interests were the specimens' maximum latera...

Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young's modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young's modulus, and it can be particularly useful for the initial stage of orthodontic treatments. PMID:21343211

Abstract Objective: To evaluate and compare the root surface morphological changes after 980-nm diode laser-aided circumferential supracrestal fiberotomy (CSF) on fluorosed and non-fluorosed teeth. Materials and Methods: The sample comprised 27 orthodontic patients (14 males and 13 females; mean age ?=? 17.3 years) with and without fluorosis, from whom 40 fluorosed and 40 non-fluorosed premolar teeth were extracted for orthodontic reasons. Conventional (control group) and laser-aided (experimental group) CSF was performed on fluorosed and non-fluorosed teeth indicated for orthodontic extraction, using a scalpel and a 980-nm diode laser at 2.5 W power, respectively. Subsequently, teeth were extracted, sectioned, and examined by scanning electron microscope to assess the ultrastructural changes. Results: There were differences in surface morphology among fluorosed and non-fluorosed roots in the control group. The root specimens of both fluorosed and non-fluorosed teeth irradiated by diode laser exhibited no evidence of smear layer, laser-induced pitting or cavitation, linear cuts/markings, carbonization of surface, and heat-induced surface cracking. However, a glazed or slightly melted appearance was observed in root specimens of fluorosed teeth after diode laser irradiation. Conclusions: These findings suggest that the diode laser-aided CSF procedure is free from thermal hazard on non-fluorosed root surfaces but may provoke some thermal changes on fluorosed root surfaces. PMID:22889200

Objective The purpose of this study was to evaluate the surface roughness (SR) of 2 types of orthodontic archwires made by 4 different manufacturers. Methods This in vitro experimental study was conducted on 35 specimens of 7 different orthodontic archwires, namely, 1 nickel-titanium (NiTi) archwire each from the manufacturers American Orthodontics, OrthoTechnology, All-Star Orthodontics, and Smart Technology, and 1 stainless steel (SS) archwire each from the manufacturers American Orthodontics, OrthoTechnology, and All-Star Orthodontics. After analyzing the composition of each wire by energy-dispersive X-ray analysis, the SR of each wire was determined by scanning electron microscopy (SEM) and surface profilometry. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests (? wires manufactured by Smart Technology, American Orthodontics, OrthoTechnology, and All-Star Orthodontics were 1,289 ± 915 A°, 1,378 ± 372 A°, 2,444 ± 369 A°, and 5,242 ± 2,832 A°, respectively. The average SR of SS wires manufactured by All-Star Orthodontics, OrthoTechnology, and American Orthodontics were 710 ± 210 A°, 1,831 ± 1,156 A°, and 4,018 ± 2,214 A°, respectively. Similar to the results of profilometry, the SEM images showed more defects and cracks on the SS wire made by American Orthodontics and the NiTi wire made by All-Star Orthodontics than others. Conclusions The NiTi wire manufactured by All-Star Orthodontics and the SS wire made by American Orthodontics were the roughest wires. PMID:13741513

Abstract in portuguese O objetivo deste estudo foi avaliar a influência de diferentes aparelhos de luz tipo LED na colagem de bráquetes ortodônticos, através do teste de resistência ao cisalhamento e do Índice de Remanescente do Adesivo (IRA). Coroas de 60 incisivos bovinos receberam a colagem de bráquetes com compósito Transbond XT. A amostra foi dividida em 4 grupos (n=15) de acordo com os seguintes tipos de fotoativação: HL: controle, luz halógena; OR= Ortholux LED; UL= Ultraled X (more) P e RD= Radii LED. Todas as fotoativações foram realizadas por 40 s. O teste de resistência ao cisalhamento foi realizado em máquina universal de ensaios mecânicos à velocidade de 0,5 mm/min. Os dados foram analisados estatisticamente pelo ANOVA e teste de Tukey. Os escores do IRA foram avaliados em lupa estereoscópica e analisados estatisticamente pelo teste de Kruskal-Wallis. O nível de significância de 5% foi adotado para todas as análises. Os valores médios (MPa) e o desvio-padrão do teste de resistência ao cisalhamento foram 9,82 (3,28), 12,70 (3,35), 9,04 (2,80) e 11,22 (2,36) para o grupo HL, OR, UL e RD, respectivamente. O grupo OR apresentou os maiores valores médios de resistência ao cisalhamento. O grupo HL diferiu significativamente (p Abstract in english The aim of this study was to assess the influence of different light-emitting diodes (LED) light-curing devices for bonding orthodontic brackets, using the shear bond strength and analysis of adhesive remnant index (ARI). Crowns from 60 bovine incisors received brackets bonded with Transbond XT. Specimens were divided into 4 groups (n=15) according to the light-curing procedures: HL = control, halogen light; OR = Ortholux LED; UL = Ultraled XP, and RD = Radii LED. All lig (more) ht-curing procedures were performed for 40 s. Shear bond strength test was evaluated using an universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test. The ARI scores were evaluated with a stereoscopic magnifying glass and analyzed statistically by Kruskal-Wallis test. A significance level of 5% was set for all analyses. Shear bond strength means in MPa and standard deviations were 9.82 (3.28), 12.70 (3.35), 9.04 (2.80) and 11.22 (2.36) for HL, OR, UL and RD, respectively. OR presented the highest shear bond strength mean value. HL differed significantly (p

Patients with cleft lip and palate can suffer from contraction of the maxillary arch and anterior cross-bite accompanied by skeletal growth retardation. We use an appliance called an external-expansion arch and induce maxillary protraction using a facial mask in order to correct the anterior cross-bite and maxillary retrusion. In this paper, the method of application of these appliances and the effects of this therapy are reported here. The external-expansion arch consists of a labial wire, bands and a sectional arch. The 0.045-inch stainless steel wire extends along the maxillary dental arch. Hooks are soldered immediately distal to the lateral incisor and the distal leg of the vertical loop. The brackets are bonded to the maxillary anterior teeth, and a 0.016×0.016 inch sectional arch is set. The external-expansion arch is inserted into the headgear tube and ligated with the sectional arch using elastic thread. The maxillary bone is pulled by use of the facial mask and the elastic band. For traction, the force is about 300 g on each side, applied parallel to the occlusal plane or slightly downward. The duration of use is 8 to 12 hours per day. The external-expansion arch has several advantages: it can be applied from the early period of Hellman's dental age IIIA or IIC to improve anterior cross-bite. As it is easy to expand the anterior teeth and move individual teeth to the labial and buccal sides, establishment of a dental arch from severe collapse is not difficult. When an expanding device such as the Quad-helix is incorporated, lateral expansion becomes easier. Furthermore, it is easy to control the teeth vertically, and patient compliance is not necessary. Hence, this method is effective as a phase 1 treatment for orthodontic patients with cleft lip and palate characterized by maxillary retardation.   

To determine the effects of static frictional resistance on varying the ligation technique in a Delta Force bracket system (Ortho Organizers Ltd, Hampton, UK) and using increasing degrees of bracket/archwire angulation to simulate binding.

4.0 Structural failure of actuator brackets/compliance ring or attach bolts ... Synthetic Rubber, Polysulfide ... actuator arm is secured in the clevis-type actuator bracket by a stud with safety wired jam nuts ..... All lifting hooks and slings are fitted ...

Nickel-Titanium wires not only show the well known shape memory effect, but also pseudoelastic behaviour. This means, as the material is bent in a wide range of tension, the stress in the material stays constant. This special behaviour allows the improvement of orthodontic devices. The investigation of wires for this application reveals great differences in the surface roughness of the wires from various suppliers. The roughness causes a loss of spring energy for the orthodontic wire by frictional effects. The investigation of the mechanical behaviour of these materials leeds to differences compared with the ideal behaviour expected for the stress/strain curve. Obviously these differences are caused by surface effects of the wires. To evaluate these questions intensive roughness measurements with profilometry, laser spectroscopy and scanning force microscopy have been performed. Further more defined bending and tensile experiments have been carried out and corresponding roughness and structure analysis with the scanning force microscope has been taken into account. By etching the wires significant surface effects could be found. (orig.)

We establish an efficient compatibility criterion for a system of generalized complete intersection type in terms of certain multi-brackets of differential operators. These multi-brackets generalize the higher Jacobi- Mayer brackets, important in the study of evolutionary equations and the integrabi...

Background. Studies have shown conflicting results on the association between nickel exposure from orthodontic appliances and nickel sensitization. Objectives & Method. In a cross-sectional study, we investigated the association between nickel sensitization and exposure to orthodontic appliances and piercings. 4376 adolescents were patch tested following a questionnaire asking for earlier piercing and orthodontic treatment. Exposure to orthodontic appliances was verified in dental records. Results. Questionnaire data demonstrated a reduced risk of nickel sensitization when orthodontic treatment preceded piercing (OR 0.46; CI 0.27-0.78). Data from dental records demonstrated similar results (OR 0.61, CI 0.36-1.02), but statistical significance was lost when adjusting for background factors....

The aim of this study was to analyse leachable monomers, additives, and degradation products from polymer-based orthodontic base-plate materials. One heat-cured resin (Orthocryl), one light-cured (Triad VLC), and three thermoplastic materials (Biocryl C, Essix A+, and Essix Embrace) were investigated. Elution was performed in water at 37degreeC for 10 days. The extract medium was changed and analysed daily. Chromatographic methods were used to identify and quantify the leachables. In addition, the content of residual methyl methacrylate (MMA) was quantified in the poly(methyl methacrylate) (PMMA)-based materials. Statistical analysis of the quantitative results was performed using a t-test for comparison of two independent samples. Monomers and additives leached from the materials polymeri...

Abstract in english OBJECTIVE: General dentist orthodontic practice is a controversial issue and this paper aims to analyze it comparing foreign laws to Brazilian Legal System. METHODS: Regulations and scientific texts concerning orthodontic practice by general dentists, in Portuguese or English language, were sought. RESULTS AND CONCLUSION: Portugal clearly forbids general dentist orthodontic practice; United States of America do not clearly forbid general dentist orthodontic practice, but (more) do regulate and promote campaigns to encourage public to seek specialist service; in Australia and England, corrective orthodontics are offered both by orthodontists and general dentists; it was not possible to evaluate how orthodontic services are provided in Eastern Europe; and the fact that general dentists are forbidden to practice corrective orthodontics in Brazilian Legal System is compatible to other countries policy.

OBJECTIVES: Aim of the research is to compare the orthodontic appliances fabricated by using rapid prototyping (RP) systems, in particular 3D printers, with those manufactured by using computer numerical control (CNC) milling machines. 3D printing is today a well-accepted technology to fabricate orthodontic aligners by using the thermoforming process, instead the potential of CNC systems in dentistry have not yet been sufficiently explored. MATERIALS AND METHODS: One patient, with mal-positioned maxillary central and lateral incisors, was initially selected. In the computer aided virtual planning was defined that, for the treatment, the patient needed to wear a series of 7 removable orthodontic appliances (ROA) over a duration of 21 weeks, with one appliance for every 3 weeks. A non-contact reverse engineering (RE) structured-light 3D scanner was used to create the 3D STL model of the impression of the patient's mouth. Numerical FEM simulations were performed varying the position of applied forces (discrete and continuous forces) on the same model, simulating, in this way, 3 models with slice thickness of 0.2mm, 0.1mm (RP staircase effect) and without slicing (ideal case). To define the areas of application of forces, two configuration "i" and "i-1" of the treatment were overlapped. 6 patients to which for three steps (3rd, 4th and 5th step) were made to wear aligners fabricated starting from physical models by 3D printing (3DP-ROA) and afterwards, for the next steps (6th, 7th and 8th step), aligners fabricated starting from physical models by CNC milling machine (CNC-ROA), were selected. RESULTS: For the 6 patients wearing the CNC-ROA, it was observed a best fitting of the aligner to the teeth and a more rapid teeth movement than the 3DP-ROA (2 weeks compared to 3 weeks for every appliance). FEM simulations showed a more uniform stress distribution for CNC-ROA than 3DP-ROA. CONCLUSIONS: In this research, 6 different case studies and CAD-FEM simulations showed that, to fabricate an efficient clear and removable orthodontic aligner, it is necessary to consider a compromise of several factors. A lower staircase effect (lower layer thickness) and a higher physical prototype accuracy allow a better control of tooth movement. PMID:23140842

Potentiometric stripping analysis (PSA) with oxygen as the oxidant has been used to determine soluble zinc and copper levels in exfoliated human teeth (all of which required extraction for orthodontic reasons) and commercial dental materials. The soluble zinc and copper contents of teeth were slightly below the zinc and copper contents in whole teeth reported by other researchers, except in the case of tooth with removed amalgam filling. Soluble zinc and copper concentrations of the dental materials and metalceramic crowns were 0.50-6.30, and of 2.00-4.30mg/g, respectively. The results of this work suggest that PSA may be a good method for zinc and copper leaching studies during the investigation of dental prosthetic materials' biocompatibility. Corrosive action of acidic media as evidence...

A rack assembly comprising brackets for attachment to a face conveyor and each comprising a pair of facing walls, and a pinwheel rack for advancing a shearer loader used underground, the rack comprising discrete sections having at both ends of each section lugs which are disposed below the rack plane and by which the sections engage in the recessed part of a respective bracket and are retained therein by one connecting pin each, the same being disposed transversely of the rack length and extending through a bore in the lug and being mounted in the two walls of the bracket, the brackets being disposed below the pins of the rack, and all the sections of the rack bear, by way of those rack pins disposed above the brackets, on one of the bracket walls disposed below the rack pins, and/or have a lateral track which bears on the other bracket wall.

Abstract in english ABSTRACT OBJECTIVE: The objective of the present study was to verify the hypothesis that no difference in biocompatibility exists between different orthodontic adhesives. MATERIAL AND METHODS: Thirty male Wistar rats were used in this study and divided into five groups (n=6): Group 1 (control, distilled water), Group 2 (Concise), Group 3 (Xeno III), Group 4 (Transbond XT), and Group 5 (Transbond plus Self-Etching Primer). Two cavities were performed in the subcutaneous do (more) rsum of each animal to place a polyvinyl sponge soaked with 2 drops of the respective adhesive in each surgical loci. Two animals of each group were sacrificed after 7, 15, and 30 days, and their tissues were analyzed by using an optical microscope. RESULTS: At day 7, Groups 3 (Transbond XT) and 4 (Xeno III) showed intense mono- and polymorphonuclear inflammatory infiltrate with no differences between them, whereas Groups 1 (control) and 2 (Concise) showed moderate mononuclear inflammatory infiltrate. At day 15, severe inflammation was observed in Group 3 (Transbond XT) compared to other groups. At day 30, the same group showed a more expressive mononuclear inflammatory infiltrate compared to other groups. CONCLUSION: Among the orthodontic adhesive analyzed, it may be concluded that Transbond XT exhibited the worst biocompatibility. However, one cannot interpret the specificity of the data generated in vivo animal models as a human response.

Research highlights: The corrosion behaviour of AISI 316L and 2205 DSS in orthodontics. The increased passive range for DSS 2205 compared to AISI 316L in artificial saliva. Higher R{sub p} values of DSS compared to AISI 316L in artificial saliva. The main constituent of the passive layers on DSS at the OCP in saliva was Cr-oxide. DSS 2205 is suitable for orthodontic applications in artificial saliva. - Abstract: The evolution of the passive films on 2205 duplex stainless steel (2205 DSS) and AISI 316L stainless steel in artificial saliva, and with the addition of fluoride, was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic measurements. The extent of the passive range increased for the 2205 DSS compared to the AISI 316L in both solutions. The formation of the passive film was studied by EIS at the open-circuit potential (OCP). The passive layers were studied at the OCP by X-ray photoelectron spectroscopy (XPS). The passive films on both materials predominantly contained Cr-oxides, whereas the Fe species were markedly depleted.

The NiTi alloy (Nitinol), with its favorable micro-structured properties and self-passivity (resembling that of pure Ti) is used as an implant material for arterial stents and orthodontic wires. During the long term contact of the alloy with aggressive environment of human body, corrosion by releasing Ni^2^+ ions can occur. Thus, the usefulness of such material can be dramatically enhanced if its interface structure and surface chemistry are controlled. The octadecylphosphonate interface (ODP) synthesis, which involves a self-assembled covalently (monodentate type) bonded film of octadecylphosphonic acid (ODPA) on the oxide covered NiTi surface, produces stable and corrosion resistant interfaces. This paper introduces integrated approach to the characterization of the NiTi/ODP interfacial ...

Objectives. The aim of this study was to assess the influence of resistance to sliding on expression of superelastic properties of NiTi wires. Methods and Materials. A three-point bending test was performed for 0.014 NiTi wire engaged in self-ligating (Damon, SmartClip, In-Ovation) and conventional brackets (Victory) ligated with regular and reduced friction modules (Slide). The wire was deflected in the buccal direction and allowed to straighten. The maximum load, unloading plateau and unloading capacity were registered. Results. The lowest activation load was required in the active self-ligating group (In-Ovation 2.2 ± 0.4?N) and reduced friction module group (Victory/Slide 2.9 ± 0.4?N), followed by the passive self-ligating systems (Damon 3.6 ± 0.7?N, SmartClip 3.7 ± 0.4?N). Higher activation load was obtained in the conventionally ligated group (Victory/module 4.5 ± 0.4?N). Unloading plateau phase with the load magnitude ranging from 1.27 ± 0.4?N (In-Ovation) to 1.627 ± 0.4?N (Slide) was distinct in all groups but one (Victory). Conclusions. Higher friction at flanking points reduces the net force delivered by the wire. Unloading plateau phase of NiTi load-deflection curve disappears in the conventionally ligated group thus indicating to an incomplete expression of NiTi superelastic properties. A rigid passive bracket clip amplifies resistance to sliding in an active configuration and produces a permanent deflection of the wire.

This study was conducted with aim to evaluate the efficiency of the newly introduced Opal self-ligating brackets (SLB). The chairside time saved, appliance efficiency, bracket bond failures, breakages and bracket staining in the Opal SLBs were compared with the conventional standard metal manually ligating brackets (MLBs) of MBT system. Seven patients were compared in each group. Standard light curing bonding methods were used in both the group. Chairside time saving, appliance efficiency and bracket bond failures were compared among the groups whereas staining was observed with the SLBs. Appliance efficiency was evaluated by PAR scores. Results showed significant chairside time being saved in SLBs, whereas the appliance efficiency was not significant. Bond failures were found only in SLBs as well as breakages along with staining. Henceforth, we could conclude that though SLBs had advantage of saving chairside time but also had disadvantage of losing more time with bond failures. Keywords: Self-ligating brackets, Chairside time, Appliance efficiency, Bracket staining, Plastic brackets. How to cite this article: Deshpande A, Srinivas N, Kumar KK, Mapare S. Comparison of Opal Self-Ligating Brackets with Manually Ligating Brackets. J Contemp Dent Pract 2012; 13(4):494-503. Source of support: Nil Conflict of interest: None declared. PMID:23151699

Orthodontic treatments not only displace irregular teeth but also induce responses in surrounding bone tissues. Bone remodelling is regarded as the regulatory mechanism triggered by mechanical loading. This study was aimed at investigating the effect of orthodontic loading on both tooth movement and neighbouring bone density distribution. A set of computational algorithms incorporating both external and internal remodelling mechanisms was implemented into a patient-specific 3D finite element (FE) model to investigate and analyse orthodontic treatment under four typical modes of orthodontic loading. The consequence of orthodontic treatment was reproduced numerically by using this FE-based technique. The results indicated that the diverse modes of orthodontic loading would result in different magnitudes of tooth movement and particular morphology of bone density distribution. It is illuminated that the newly developed algorithms may replicate the clinical situation more closely compared with the previous proposed method. PMID:23148454

A series of three hydrogen in titanium alloy Standard Reference Materials (SRMs 2452, 2453, and 2454) was prepared with hydrogen mass fractions bracketing the hydrogen specification limit of 125?mg/kg. Commercial titanium alloy Ti6Al4V (6?pct aluminum and 4?pct vanadium) was heated under vacuum in a furnace to remove native hydrogen, then it was doped with a measured quantity of hydrogen. Prompt gamma-ray activation analysis was used to determine hydrogen in the degassed material and finished SRMs. A combination of preparation data and PGAA measurement was used to certify the hydrogen mass fraction of each. The certified hydrogen mass fractions are 62.5?mg/kg???1.6?mg/kg for SRM 2452, 114?mg/kg???5?mg/kg for SRM 2453, and 211?mg/kg???4?mg/kg for SRM 2454.

The expected environmental conditions for emplaced waste packages in a salt repository are simulated in the materials testing program to evaluate performance. Synthetic brines, based on the analyses of actual brines (both intrusion and inclusion), are used for corrosion and leach testing. Elevated temperatures (to 150/sup 0/C) and radiation fields of up to 10/sup 3/ rad/h are employed as conservative conditions to bracket expected performance and provide data for worst case scenarios. Obtaining a precise definition of the waste package environment in a salt repository and its change with time is closely tied to detailed site characterization of the candidate salt repository horizon. It is expected that field testing can augment some of the materials testing currently under way and can provide increased confidence in the predicted site-specific near-field conditions. 17 references, 5 figures, 1 table.

We use the vector wedge product in geometric algebra to show that Poisson commutator brackets measure preservation of phase space areas. We also use the vector dot product to define the Poisson anticommutator bracket that measures the preservation of phase space angles. We apply these brackets to the paraxial meridional complex height-angle ray vectors that transform via a 2x2 matrix, and we show that this transformation preserves areas but not angles in phase space. The Poisson brackets here are expressed in terms of the coefficients of the ABCD matrix. We also apply these brackets to the distance-height ray vectors measured from the input and output sides of the optical system. We show that these vectors obey a partial Moebius transformation, and that this transformation preserves neither areas nor angles. The Poisson brackets here are expressed in terms of the transverse and longitudinal magnifications.

Abstract in portuguese INTRODUÇÃO: torna-se difícil, sem a utilização de um índice oclusal, uma avaliação fidedigna dos resultados e da finalização dos tratamentos ortodônticos. O índice PAR é capaz de avaliar objetivamente as alterações que ocorrem com o tratamento ortodôntico, e as melhorias conseguidas. OBJETIVO: por isto, decidiu-se, neste estudo, avaliar-se as alterações decorrentes dos tratamentos ortodônticos realizados com aparelho fixo, mecânica Edgewise e com extra (more) ções dos quatro primeiros pré-molares, bem como a qualidade de sua finalização e de seus resultados, por meio do índice de avaliação oclusal PAR. MATERIAL E MÉTODOS: foram avaliados os modelos de estudo de 94 pacientes leucodermas, com idade média de 13,46 anos, sendo 50 do gênero masculino e 44 do feminino. O tempo de tratamento médio foi de 2,09 anos. O índice PAR foi obtido dos modelos pré e pós-tratamento de cada um dos pacientes. RESULTADOS: após a realização da análise estatística descritiva, pode-se observar que o índice PAR inicial médio de 29,46 foi reduzido para 6,32 ao final do tratamento, caracterizando uma redução de 78,54% com o tratamento ortodôntico. Houve correlação do índice PAR inicial com a correção deste índice durante o tratamento. CONCLUSÃO: pode-se concluir que os casos tratados demonstraram um bom padrão de finalização ortodôntica, e quanto maior a severidade da má oclusão, maior a correção com o tratamento. Abstract in english INTRODUCTION: a trustworthy evaluation of orthodontic treatment outcomes without using an occlusal index becomes difficult. The PAR index is capable of objectively assess treatment changes and the real improvement. OBJECTIVE: due to this, it was decided to evaluate orthodontic treatment changes with fixed appliances, Edgewise mechanics and four premolars extractions, as well as the quality of finishing occlusion, using the PAR index. MATERIAL AND METHODS: study casts of 9 (more) 4 white patients (50 males and 44 females) were evaluated. The mean pre-treatment age was 13.46 years and the mean treatment time was 2.09 years. The PAR index was obtained from pre-treatment and post-treatment study casts of each patient. RESULTS: after the accomplishment of statistical analysis, it could be observed that the mean initial PAR index of 29.46 was reduced to 6.32 at post-treatment stage, achieving a reduction of 78.54% with treatment. There was correlation between the initial PAR index and correction during treatment. CONCLUSION: it could be concluded that the treated cases presented a high standard orthodontic finishing, and the more severe the malocclusion, the more will be the treatment changes.

The dynamics of Vlasov kinetic moments is shown to be Lie-Poisson on the dual Lie algebra of symmetric contravariant tensor fields. The corresponding Lie bracket is identified with the symmetric Schouten bracket and the moment Lie algebra is related with a bundle of bosonic Fock spaces, where creation and annihilation operators are used to construct the cold plasma closure. Kinetic moments are also shown to define a momentum map, which is infinitesimally equivariant. This momentum map is the dual of a Lie algebra homomorphism, defined through the Schouten bracket. Finally the moment Lie-Poisson bracket is extended to anisotropic interactions.

We report on the first in situ chemical investigation of vapor-liquid-solid semiconductor nanowire growth and reveal the important, and previously unrecognized, role of transient surface chemistry near the triple-phase line. Real-time infrared spectroscopy measurements coupled with postgrowth electron microscopy demonstrate that covalently bonded hydrogen atoms are responsible for the (left angle bracket 111 right angle bracket) to (left angle bracket 112 right angle bracket) growth orientation transition commonly observed during Si nanowire growth. Our findings provide insight into the root cause of this well-known nanowire growth phenomenon and open a new route to rationally engineer the crystal structure of these nanoscale semi-conductors. PMID:22594623

Henneman S, Reijers RR, Maltha JC, Von den Hoff JW. Local variations in turnover of periodontal collagen fibers in rats. J Periodont Res 2012; 47: 383-388. 2011 John Wiley & Sons A/S Background and Objective:- The exact cause of orthodontic relapse is still unclear, although it is often suggested to be caused by periodontal collagen fibers. We hypothesize that long-lived collagen fibers in the periodontium cause relapse. The aim was to determine the half-life of periodontal collagen fibers around rat molars. Material and Methods:- Thirty weanling rats were repeatedly injected with 3H-proline, and autoradiography of histological sections was performed at 1, 4, 8, 15, 22, 29, 36, 57, 78 and 113-d after labeling. Grain densities determined in specific areas of the periodontium were used to ca...

Aim To conduct a systematic literature review on the impact of juvenile idiopathic arthritis (JIA) on craniofacial morphology. Materials and methods Several electronic databases (PubMed, Medpilot, Web of Science, DIMDI) were systematically searched for studies that were published up to and including May 2011. In addition, a manual search of the orthodontic and rheumatologic literature was conducted, and reference lists of the selected articles were checked for relevant publications. The identified articles were independently assessed by two investigators and selected according to a three-step process (title/abstract/full text). Results After completion of the selection procedure, 19 articles were identified possessing great heterogeneity. In most of them, no differentiated analysis of the...

Lateral loads exerted on the maxillofacial region by habitual postures and habits may cause lateral shift or deformity of the mandible. These loads were measured with a desktop dynamic-strain gauge (DPM-600, Kyowa Co.) connected to a small, highly sensitive pressure sensor (PSL-A type, Kyowa Co.), and recorded with an oscillographic recorder (RDM-100A, Kyowa Co.). Measurements were taken with a pressure sensor embedded in silicone impression material placed in a vinyl chloride resin bag, on which pressures were applied. A preliminary study was conducted to obtain a proportional constant and a conversion formula for load calculation. The subsequent main study included 20 healthy male volunteers for load measurement in 12 positions. The mean load exerted on the mandible was 43.7N when the subjects lay face down and approximately 20N when they sat resting the lateral part of the chin on the hand, indicating that these loads are greater than regular orthodontic forces.   

Abstract Objective: The aim of this study was a radiographic mesiodistal analysis of the shape of the bone crest 3 months after tooth removal. Material and methods: One hundred single tooth extractions were performed on 100 patients because of orthodontic or prosthetic causes. Bite blocks were used for two radiographs: one on the day of extraction and the other after healing of the socket, 3 months later. These X-rays were used to determine: (1) the most apical distance of alveolar ridge resorption, with baseline as the line between bone-to-teeth contact (the greatest distance in bone resorption height) and (2) the mesiodistal distance (MDD) and mesial and distal angles arising after bone tissue modeling. Results: Significant differences (P<0.05) emerged between the MDDs of multiple- [8 mm...

Introduction: The early treatment of Class III malocclusion with a protraction facemask can produce forward movement of the maxilla but is generally associated with posterior rotation of the mandible and dentoalveolar compensations. This article shows the dental and skeletal effects of intermaxillary elastics applied to temporary anchorage devices in the treatment of maxillary deficient Class III patients. Materials and methods: A total of 6 patients with skeletal Class III malocclusion were treated with intermaxillary elastics only. This traction was applied between modified miniplates placed in the maxilla and a modified lower acrylic resin plate bonded on mandibular tooth surfaces. To evaluate the orthodontic changes, lateral cephalograms were taken at the start of the treatment (T1), a...

Development of an optimal design of multilayer dentures has involved studies of the effects of the material used to make the intermediate layer, its thickness and mode of application on the corrosive electrochemical behavior of orthodontic articles. Application of intermediate layers was found to reduce the magnitude of polarization current and improve the corrosion resistance of a soldered structure. The best effect was achieved with the design with a protective coating of Cr-Ti composition of stainless steel, applied by vacuum method, and galvanic Cr. The corrosion protecting characteristics of this sublayer were found to depend on the quality of the soldered junction: if it is defective, the protective effect is poor whatever the type of coating. The study has confirmed the necessity of protective coatings application to soldered half-finished articles and the efficacy of multilayer coatings with the surface layer of titanium nitride. PMID:1980755

Objectives: To evaluate the body posture and plantar arches of patients with posterior unilateral crossbite. Materials and methods: We examined 24 patients: 12 with posterior unilateral crossbites (study group) and 12 with no orthodontic problems in the transversal plane (controls group). Each participant was subjected to a baropodometric evaluation with the eyes open and stabilometric evaluations with the eyes closed and open. These variables were evaluated: percentage of body weight distributed on each foot, length and velocity of oscillations from the body's center of pressure (COP) during testing with the eyes closed. Mean values and standard deviations were calculated for each variable. The Student's t-test was used to compare postural parameters of the two groups. Results: The two gr...

The substitution of conventional components for NiTi in distinct devices such as actuators, valves, connectors, stents, orthodontic arc-wires, e.g., usually demands some kind of treatment to be performed on the surface of the alloy. A typical case is of biomaterials made of NiTi, in which the main drawback is the Ni out-diffusion, an issue that has been satisfactorily addressed by plasma based ion implantation (PBII). Even though PBII can tailor selective surface properties of diverse materials, usually, only thin modified layers are attained. When NiTi alloys are to be used in the harsh space environment, as is the case of devices designed to remotely release the solar panels and antenna arrays of satellites, e.g., superior mechanical and tribological properties are demanded. For this cas...

Background and objective Orthodontic tooth movement is known to cause sterile inflammation of the periodontal ligament (PDL). It may also be accompanied by pathological effects of external apical root resorption, with interindividual differences in the incidence and extent of resorption. An involvement of autoimmunological mechanisms is currently under discussion. This study aimed to improve our understanding of similarities between the inflammatory mechanisms underlying the pathophysiology of periodontitis and root resorption. Materials and methods Human PDL cells were stimulated with interleukin (IL)-1?/IL-17A/IFN-?, or left non-stimulated. Their potential for phagocytosis was then evaluated by incubation with dextran or E. coli or S. aureus particles, followed by flow cytometric and imm...

IntroductionNickel-titanium orthodontic archwires are used with bonded appliances for initial leveling. However, precise bending of these archwires is difficult and can lead to changes within the crystal structure of the alloy, thus changing the mechanical properties unpredictably. The aim of this study was to evaluate different bending methods in relation to the subsequent mechanical characteristics of the alloy. Materials and MethodsThe mechanical behaviors of 3 archwires (Copper NiTi 35degreeC [Ormco, Glendora, Calif], Neo Sentalloy F 80 [GAC International, Bohemia, NY], and Titanol Low Force [Forestadent, Pforzheim, Germany]) were investigated after heat-treatment in a dental furnace at 550-650degreeC, treatment with an electrical current (Memory-Maker, Forestadent), and cold forming. ...

Objective In dentistry, metallic alloys are used for dentures, restorative materials, and orthodontic devices. Electric voltages up to 950 mV may occur between different dental alloys in the oral cavity. This study aimed to investigate physiologic reactions of oral leukoplakia cells in vitro to electric fields. Study Design A human leukoplakia cell line (MSK-LEUK1), cultivated in keratinocyte growth medium (KGM-2) supplemented with growth factors in 5% CO2 humidified air at 37°C, was exposed to electric field strength of 1-20 V/m for 24 hours in a custom-made pulse chamber. The cells were then analyzed for proliferation with the use of BrdU assay and for apoptosis with the use of TUNEL assay. Findings were assessed with the use of fluorescent microscopy. Ultrastructural changes were...

Xu C, Hao Y, Wei B, Ma J, Li J, Huang Q, Zhang F. Apoptotic gene expression by human periodontal ligament cells following cyclic stretch. J Periodont Res 2011; 46: 742-748. 2011 John Wiley & Sons A/S Background and Objective:- Periodontal ligament cells play an important role in maintaining homeostasis of periodontal tissue upon mechanical force loading caused by mastication or orthodontic force. Previous studies revealed force-driven periodontal ligament cell death via apoptosis, but the force-sensing genes assigned to the apoptotic pathway have not been fully characterized. The present study aimed to identify force-sensing genes implicated in the apoptotic pathway in periodontal ligament cells. Material and Methods:- Human periodontal ligament cells were exposed to 20% stretch strain for...

A three dimensional rigid-plastic finite element model is established to simulate the isothermal precision forging process of the magnesium alloy bracket based on DEFORM 3D in order to analyze the material flow rule and determine the forging process scheme. Some problems such as underfilling and too large forging pressure are predicted and resolved through optimizing the shapes of the billet successfully. Compared to the initial microstructure, the isothermal-forged microstructure of the alloy refines obviously and amounts of secondary phases precipitate on the matrix during isothermal forging process. In subsequent ageing process, large quantities of secondary phases precipitate from a-Mg matrix with increasing ageing time. The optimal comprehensive mechanical properties of the alloy have...

A thermodynamic model of glass durability based on hydration of structural units has been applied to natural glass, medieval window glasses, and glasses containing nuclear waste. The relative durability predicted from the calculated thermodynamics correlates directly with the experimentally observed release of structural silicon in the leaching solution in short-term laboratory tests. By choosing natural glasses and ancient glasses whose long-term performance is known, and which bracket the durability of waste glasses, the long-term stability of nuclear waste glasses can be interpolated among these materials. The current Savannah River defense waste glass formulation is as durable as natural basalt from the Hanford Reservation (10/sup 6/ years old). The thermodynamic hydration energy is shown to be related to the bond energetics of the glass. 69 references, 2 figures, 1 table.

We analyze published and new paleointensity data from Apollo samples to reexamine the hypothesis of an early (3.9-3.6Ga) lunar dynamo. Our new paleointensity experiments on four samples use modern absolute and relative measurement techniques, with ages ranging from 3.3 to 4.3Ga, bracketing the putative period of an ancient lunar field. Samples 60015 (anorthosite) and 76535 (troctolite) failed during absolute paleointensity experiments. Samples 72215 and 62235 (impact breccias) recorded a complicated, multi-component magnetic history that includes a low-temperature (500degreeC) component associated with a low intensity (2mT). Similar multi-component behavior has been observed in several published absolute intensity experiments on lunar samples. Additional material from 72215 and 62235 was s...

This strategic planning exercise identified and characterized new and emerging advanced metallic technologies in the context of the drastic changes in global politics and decreasing fiscal resources. In consideration of a hierarchy of technology thrusts stated by various Department of Defense (DOD) spokesmen, and the need to find new and creative ways to acquire and organize programs within an evolving Wright Laboratory, five major candidate programs identified are: C-17 Flap, Transport Fuselage, Mach 5 Aircraft, 4.Fighter Structures, and 5. Missile Structures. These results were formed by extensive discussion with selected major contractors and other experts, and a survey of advanced metallic structure materials. Candidate structural applications with detailed metal structure descriptions bracket a wide variety of uses which warrant consideration for the suggested programs. An analysis on implementing smart skins and structures concepts is given from a metal structures perspective.

Multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has become the preferred method for precise and accurate measurements of the relative abundances of many radiogenic and stable isotopes in natural materials. Isotopic analyses by MC-ICP-MS require a correction for instrumental mass-dependent isotopic fractionation ("instrumental mass bias"). Two techniques have been used to correct for instrumental mass bias in the MC-ICP-MS: (1) standard-sample bracketing (SSB) or (2) double spiking. SSB is often cited as the preferred method, but it is more susceptible to matrix effects. Here we demonstrate that a matrix effect in the MC-ICP-MS may arise indirectly from the chemical separation and purification of molybdenum using anion exchange resin. The results of our experimen...

The objective of the present study was to evaluate the interest of both children and parents towards orthodontic treatment and compare it to the normative treatment need as well as to determine the factors related to such an interest. The sample consisted of 407 schoolchildren aged between 9 and 12 years and their parents from Nova Friburgo (Rio de Janeiro), Brazil. The orthodontic concern expressed by children and parents was obtained by means of a questionnaire. The normative need was evaluated using two components of the Index of Orthodontic Treatment Need (IOTN). Data analysis involved multiple logistic regression. Normative treatment need was greater than the children's self-perceived treatment need. The parents expressed more interest towards orthodontic treatment of their children than the children themselves. The orthodontic concern expressed by both groups was greater than the normative need for orthodontic treatment, and such a finding was associated with gender of the children (female) and self-perceived treatment need expressed by them. The lack of a relationship between the normative treatment need and the orthodontic concern of children and parents shows that such assessments should be performed when orthodontic treatment is indicated, particularly in terms of public health, as the demand is greater than the services supplied. (J Oral Sci 52, 101-107, 2010)   

Abstract in english Despite the different orthodontic approaches to Class II subdivision malocclusions one has also to consider the skeletal components before undertaking any treatment protocol. Significant involvement of the skeletal structures may require a combined surgical orthodontic treatment, which has remained stable for more than four years, as illustrated in this case report.

Abstract in portuguese Este estudo in vitro foi delineado para comparar a força gerada por cadeias elastoméricas e por molas fechadas de NiTi comercialmente disponíveis e para determinar seu padrão de degradação de forças. Para tal, 40 segmentos de cadeia elastomérica e 40 molas fechadas de NiTi foram divididas em 4 grupos de acordo com a marca comercial: (1) Morelli®, (2) Abzil®, (3) TP Orthodontics® e (4) American Orthodontics®. As amostras foram distendidas ao dobro de seu compri (more) mento original e imersas em solução de saliva artificial a 37°C. Uma máquina de ensaio (Instron) foi utilizada para aferir a força inicial e em 1, 4, 7, 14, 21 e 28 dias. Os resultados mostraram que as cadeias elastoméricas liberaram uma força média inicial de 404 g para a marca TP Orthodontics®, 402 g para Abzil®, 351 g para American Orthodontics® e 347 g para Morelli®. As molas fechadas de NiTi geraram uma força média inicial de 223 g para a marca Morelli®, 216 g para Abzil®, 208 g para TP Orthodontics® e 196 g para American Orthodontics®. A percentagem média de degradação da força após 28 dias para as cadeias elastoméricas foi de 37,4% para TP Orthodontics®, 48,1% para American Orthodontics®, 65,4% para Morelli® e 71,6% para Abzil®. A percentagem média de degradação da força após 28 dias para as molas fechadas de NiTi foi de 22,6% para American Orthodontics®, 29,8% para Abzil®, 30,6% para Morelli® e 45,8% para TP Orthodontics®. Ao final do experimento, observaram-se diferenças significantes entre as cadeias elastoméricas e as molas fechadas de NiTi. Os resultados permitem recomendar as molas fechadas de NiTi estudadas como dispositivos mais adequados para movimentação dentária do que as cadeias elastoméricas. Abstract in english This in vitro study was designed to compare the forces generated by commercially available elastomeric chains and NiTi closed coil springs, and to determine their force decay pattern. Forty elastomeric chains and forty NiTi closed coil springs were divided into 4 groups according to the following manufacturers: (1) Morelli®, (2) Abzil®, (3) TP Orthodontics® and (4) American Orthodontics®. The specimens were extended to twice their original length and stored in artific (more) ial saliva at 37°C. Initial force was measured by means of an Instron universal testing machine and then at 1, 4, 7, 14, 21, and 28 days. The results revealed that the elastomeric chains delivered a mean initial force of 347 g for Morelli®, 351 g for American Orthodontics®, 402 g for Abzil®, and 404 g for TP Orthodontics®. The NiTi closed coil springs generated a mean initial force of 196 g for American Orthodontics®, 208 g for TP Orthodontics®, 216 g for Abzil®, and 223 g for Morelli®. The mean percentage of force decay observed after 28 days for the elastomeric chains was 37.4% for TP Orthodontics®, 48.1% for American Orthodontics®, 65.4% for Morelli®, and 71.6% for Abzil®. After 28 days, the NiTi closed coil springs presented a mean percentage of force decay of 22.6% for American Orthodontics®, 29.8% for Abzil®, 30.6% for Morelli®, and 45.8% for TP Orthodontics®. At the end of the study, significant differences were observed between the elastomeric chains and the NiTi closed coil springs. The results indicated that the studied NiTi closed coil springs are more adequate for dental movement than the elastomeric chains.

Optimum treatment timing for orthodontic problems continues to be one of the more controversial topics in orthodontics. Especially regarding the correction of Class III malocclusion, there is little consensus as to proper timing or methods for correcting these problems. The orthopedic approach for growth modification is usually limited to children with growth remaining subjected to non hereditary pattern. If the skeletal malocclusion is within the range of an orthodontic treatment, fixed orthodontic appliances with dentoalveolar compensation mechanism can achieve a normal occlusion. Otherwise in patients with a severe skeletal discrepancy, it will be necessary to consider a combined surgical and orthodontic approach. The purpose of this study was to describe treatment planning according to the age and to the initial diagnosis. The management of skeletal Class III malocclusion is still a challenge to orthodontists especially because of relapse due to the late growth of the mandible. PMID:21914432

Abstract in portuguese INTRODUÇÃO: os materiais elastoméricos são considerados importantes fontes de força para a movimentação ortodôntica. OBJETIVO: avaliar a liberação de tensões de quatro marcas comerciais de elásticos ortodônticos em cadeia (Morelli, Ormco, TP e Unitek), em função do tempo, quando mantidas tensionadas por uma força inicial de 150g e imersas em saliva artificial a 37ºC. MÉTODOS: os elásticos em cadeia foram tensionados entre pinos de aço, fixados em uma p (more) laca de resina acrílica à distância de 15mm (Morelli e TP) e de 16mm (Unitek e Ormco), ambas medidas correspondendo a uma força de 150g. A leitura da quantidade de tensão liberada pelos elásticos foi realizada com um dinamômetro nos intervalos 30 minutos, 7, 14 e 21 dias. Os dados obtidos foram submetidos à análise de variância (ANOVA) (p Abstract in english INTRODUCTION: Elastomeric materials are considered important sources of orthodontic forces. OBJECTIVE: To assess force degradation over time of four commercially available orthodontic elastomeric chains (Morelli, Ormco, TP and Unitek). METHODS: The synthetic elastics were submerged in 37 ºC synthetic saliva and stretched by a force of 150 g (15 mm - Morelli and TP; 16mm - Unitek and Ormco). With a dynamometer, the delivered force was evaluated at different intervals: 30 (more) minutes, 7 days, 14 days and 21 days. The results were subjected to ANOVA and Tukey's test. RESULTS: There was a force decay between 19% to 26.67% after 30 minutes, and 36.67% to 57% after 21 days of activation. CONCLUSIONS: TP elastomeric chains exhibited the smallest percentage of force decay, with greater stability at all time intervals tested. Meanwhile, the Unitek chains displayed the highest percentage of force degradation, and no statically significant difference was found in force decay between Ormco and Morelli elastomeric chains during the study period.

The purpose of this study was to investigate the harmonious facial profile before and after orthodontic treatment on permanent dentition and to determine the factors which influence lateral facial harmony. Materials were lateral Roentgen cephalograms from 150 subjects (25 males and 25 females each in 3 groups-maxillary protrusion, mandibular protrusion and crowding-) taken before and after treatment. The average age before treatment was 11 years and 6 months and, after treatment, was 14 years and 3 months. The term of active treatment was 2 years and 9 months. Lateral facial evaluation based on the external profile line was performed by a group of 40 persons which included dental students and the general public. In the 5 stage evaluation, each subject could receive from 40 to 200 points. The subjects with more than 121 points were classified in the harmonious group; those with less than 120 points were classified in the disharmonious group. Subjects who had been classified as disharmonious before treatment but became harmonious after treatment constituted the improved group. Subjects classified disharmonious before treatment who remained disharmonious after treatment constituted the unimproved group. The value of the overall harmonious group before treatment was 8.6% and, after treatment, was 36.6%. The increase in the percentage of cases classified as harmonious varied among the different occlusal types: for the mandibular protrusion, the value before treatment was 2% and after treatment was 32%, for crowding it was 18% before and 46% after treatment, and for maxillary protrusion, it was 6% before and 32% after treatment. The ratio of percentage in the harmonious group increased on every malocclusion group after treatment, suggesting the importance of orthodontic treatment for improvement of lateral facial harmony. Before treatment, the morphological conditions in the improved group were more advantageous than those in the unimproved group.   

The role of projectors associated with Poisson brackets of constrained Hamiltonian systems is analyzed. Projectors act in two instances in a bracket: in the explicit dependence on the variables and in the computation of the functional derivatives. The role of these projectors is investigated by usin...

Using the scattering transform for $n^{th}$ order linear scalar operators, the Poisson bracket found by Gel'fand and Dikii, which generalizes the Gardner Poisson bracket for the KdV hierarchy, is computed on the scattering side. Action-angle variables are then constructed. Using this, complete integrability is demonstrated in the strong sense. Real action-angle variables are constructed in the self-adjoint case.

We discuss two approaches that are used frequently to describe quantum-classical hybrid system. One is the well-known mean-field theory and the other adopts a set of hybrid brackets which is a mixture of quantum commutators and classical Poisson brackets. We prove that these two approaches are equivalent.

This note elaborates on Th. Voronov’s construction [Th. Voronov, Higher derived brackets and homotopy algebras, J. Pure Appl. Algebra 202 (1–3) (2005) 133–153; Th. Voronov, Higher derived brackets for arbitrary derivations, Travaux Math. XVI (2005) 163–186] of L?-structures via higher derived bracke...

The bracket formulation of the dynamic equations in nonequilibrium thermodynamics is examined here. After a short review of the early historical development of the subject, we present an introduction to the theoretical foundations of the one-generator bracket formalism, where the one generator is th...

We show that one can skip the skew-symmetry assumption in the definition of Nambu-Poisson brackets. In other words, a n-ary bracket on the algebra of smooth functions which satisfies the Leibniz rule and a n-ary version of the Jacobi identity must be skew-symmetric. A similar result holds for a non-antisymmetric version of Lie algebroids.

PURPOSE: To investigate and propose a method of artifact reduction arising from metallic dental materials by applying a slice-encoding for metal artifact correction (SEMAC) technique on T1-weighted spin-echo (SE) imaging at 3 Tesla. MATERIALS AND METHODS: The view angle tilting (VAT) technique was adapted to conventional T1-weighted spin-echo (SE) sequence to correct the in-plane distortion, and the SEMAC technique was used for correcting the remaining through-plane distortions. Fourier transform based B0 field simulations were performed to estimate the amount of field perturbation and a scout imaging method was developed which guide in selecting the number of slice-encodings needed in SEMAC sequences. Phantoms of six different dental materials with various shapes and sizes that are used in practice (amalgam; titanium implant; gold and Ni-Cr crowns; Ni-Ti and stainless steel orthodontic wires) were imaged. In vivo images of two subjects were also acquired. The amounts of artifact reduction were quantified in phantom studies. RESULTS: Compared with conventional SE imaging in phantom studies, in-plane artifacts were reduced by up to 43% in the VAT SE images and 80% in the SEMAC images. Through-plane artifacts were reduced by up to 65% in SEMAC images. In vivo SEMAC images also showed reduced artifacts. CONCLUSION: The SEMAC technique can mitigate artifact caused by metallic dental materials for T1w-SE imaging. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc. PMID:22941956

The two primary waste package barriers (other than the waste form itself) are the corrosion-resistant/structural component and the emplacement hole backfill. While the waste forms proposed for the NWTS program are currently projected to be borosilicate glass and spent fuel, the number of candidate materials for the other barriers is potentially quite large and must therefore be reduced. This is being accomplished through materials screening test programs. The major NWTS programs for the development and testing of corrosion-resistant/structural components and emplacement hole backfills have been performed by Sandia National Laboratories (SNL) for salt media and by Pacific Northwest Laboratory (PNL) for basalt and salt. Materials studies in support of tuff or granite repositories using specific ground waters have not yet been initiated. However, it is expected that the range of ground-water compositions characteristic of salt, sea water, basalt, and de-ionized waters used in the current studies adequately bracket the ground-water compositions for tuff and granite at least for screening purposes. In both the SNL and PNL programs initial candidate materials were selected on the basis of literature surveys and consultations with investigators in the US and abroad.

This article describes the advanced cone beam computed tomography (CBCT) applications in orthodontic diagnosis and treatment planning. The limitations of conventional 2-dimensional planar film are discussed, and case examples are described that highlight the additional diagnostic information and many benefits derived from 3-dimensional imaging. CBCT software can manipulate the Digital Imaging and Communications in Medicine (ie, DICOM) data to visualize anatomic structures and accurately display relationships within the craniofacial complex. A combination of volumetric reconstruction and multiplanar views can provide the orthodontic clinician with skeletal hard tissue, soft tissue, dentition, and airway information. Nonstandard orthodontic cases, such as impacted teeth, supernumerary odonto...

Three different types of electrochemical corrosion cells are discussed - composition, concentration, and stress cells. Annotated cases are presented for each type of corrosion cell in removable appliances using conventional photography, scanning electron microscopy, and X-ray elemental analyses. The complexity that corrosion can attain is illustrated via the case of a palatal expansion device. Specific examples of galvanic cells, which are possible in orthodontic practice, are summarized in terms of the anodic and cathodic half-cells. These include material differences, oxygen gradients, presence of debris, changes in pH, induced stress levels, changes in stress states, and variations in as-received history. A galvanic series is constructed from the orthodontist's perspective that includes titanium, nickel-titanium, cobalt-chromium, and stainless steel alloys, as well as glass-fiber-reinforced polymer-matrix composites. Preventative measures are presented from the perspectives of the raw material manufacturers, the dental laboratories, the chair-side practitioner, and the patient. A list of materials is provided, which are known to promote corrosion in the event that stainless steels are sensitized as a consequence of improper handling. In the final analysis, however, retainers and removable appliances are reliable if corrosion cells are conscientiously averted and preventative measures are routinely employed. PMID:11553078

Aim: To analyze the influence of bracket base mesh geometry on the stresses generated in the tooth-cement-bracket continuum by a shear/peel load case and to compare the stress generated by three different loads (masticatory, peel, and twisting) on the bracket mesh base by employing a three-dimensional (3D) finite element computer model. Methods: A validated 3D finite element model of the bracket-cement-tooth system was constructed consisting of 40,536 nodes and 49,201 finite elements. Results: An increase in the diameter of the bracket mesh base wire resulted in a decrease in the stress at the enamel and cement. Increase in wire spacing (200 to 500 mm) increased the stresses in the enamel and cement at all wire diameters, but within the impregnated wire mesh, the major stress decreased with the increase in the wire spacing. Peel load produced comparatively less stress on enamel than masticatory and twisting force. Conclusion: Alteration in mesh spacing and wire diameter influences the magnitude and distribution of stresses within the bracket-cement-tooth continuum. Peel load and twisting load are best to debond the bracket since they produced minimal stress on the enamel, which is suggestive of lower chances of enamel damage. PMID:22567656

As a supplementary structure supporting the irradiation facilities, the in-chimney bracket holds guide tubes whose holding position in CT or IR is the middle part of the instrumented facility between the hole spider and the robot arm already provided in the reactor pool liner. Also, the bracket grips the upper part of the guide tubes when it is applied to hold the instrumented facility loaded in OR sites. The irradiation test will be successfully conducted since this bracket reduces the flow-induced vibration (FIV) and the dynamic response to seismic load. The installation position of the bracket is 60 cm below the top of the chimney, i.e., thermo siphoning hole position. To evaluate the structural integrity on the in-chimney bracket and the related reactor structures, ANSYS finite element analysis model is developed and the dynamic characteristics are analyzed. The seismic response analyses were performed for the in-chimney bracket and the related reactor structures of HANARO under the design earthquake response spectrum loads of OBE and SSE. The analysis results show that the stress values in main points of reactor structures and in-chimney bracket for the seismic loads are also within the ASME code limits. It is also confirmed that the fatigue usage factor is much less than 1.0. Therefore any damage on structural integrity is not expected when the in-chimney bracket is installed at the upper part of the reactor chimney. This bracket had been designed and manufactured based on the dimensions of the as-built chimney. In the process of design and preliminary installation, chimney measurement tools, dummy chimney, and installation tools were developed and the installation procedure was prepared and verified through the installation rehearsal.

In this thesis Poisson structures of two classical gauge field theories (Maxwell-Klein-Gordon- and Maxwell-Dirac-system) are constructed using the parametrix construction of Green's functions. Parametrices for the Maxwell-Klein-Gordon- and Maxwell-Dirac-system are constructed in Minkowski space and this construction is later generalized to curved space times for the Maxwell-Klein-Gordon-system. With these Green's functions Poisson brackets will be defined as Peierls brackets. Finally non-local, gauge invariant observables, the so-called 'gauge bridges'are constructed. Gauge bridges are the matrix elements of holonomy operators. It is shown, that these emerge from Poisson brackets of local, gauge invariant observables. (orig.)

We develop a Hamiltonian discontinuous finite element discretization of a generalized Hamiltonian system for linear hyperbolic systems, which include the rotating shallow water equations, the acoustic and Maxwell equations. These equations have a Hamiltonian structure with a bilinear Poisson bracket, and as a consequence the phase-space structure, ?mass?? and energy are preserved. We discretize the bilinear Poisson bracket in each element with discontinuous elements and introduce numerical fluxes via integration by parts while preserving the skew-symmetry of the bracket. This automatically results in a mass and energy conservative discretization. When combined with a symplectic time integration method, energy is approximately conserved and shows no drift. For comparison, the discontinuous ...

... instructions, keeping scheduled orthodontic appointments and maintaining excellent oral hygiene to achieve the best results. You will also need to see your general dentist as recommended to continue your general dental care. How long does treatment take? Patients who need ...

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IntroductionMotivation and cooperation are vital components of orthodontic treatment if a good outcome is to be achieved. In this study, we used Q-methodology to investigate motivating factors among adolescents seeking orthodontic treatment and parents wanting their children to undergo orthodontic treatment. This technique asks participants to rank a series of statements, and the analysis of this ranking then provides insight into the participants’ opinions. MethodsEach of these complementary studies was divided into 2 phases: interviews to generate a list of reasons for seeking orthodontic treatment and the use of Q-methodology to assess and categorize the relative importance of these reasons for the groups of participants. In the patient study, 32 items were generated from the int...

... a combined approach of both orthodontics and surgical repositioning of the jaws is necessary. Such surgery is ... best care for my child? Children with cleft lip and/or palate require the coordinated services of ...

Anterior diastemata may compromise the harmony of a patient's smile. Consideration of etiologic factors, previous gingival conditioning, and individual treatment planning are essential in the proper management of anterior diastemata. An integrated orthodontic-restorative approach may enhance the aesthetic results when orthodontic therapy itself is not feasible. This article presents integrated orthodonticrestorative solutions of anterior diastemata, associated with the conditioning of the gingival tissue with composite resin, and discusses the most relevant aspects related to their etiology and treatment planning.

The aim of this article is to describe a method for fabricating a new esthetic maxillary retainer. To fabricate this retainer it is necessary to fit a segment of orthodontic wire in the maxillary molar and premolar region, followed by plasticization of the model. In order to allow occlusal finishing the occlusal and incisal surfaces of the plate are removed. The described retainer can be a useful alternative to the orthodontist for esthetic orthodontic retention.

The force/compression characteristics of 32 commercially available nickel titanium (NiTi) compression springs from seven distributors were investigated in vitro in order to support the orthodontist in deciding to select an appropriate spring for a given treatment. The geometrical properties of the coil springs, i.e., inner spring diameter, winding diameter and winding configuration, differed significantly, as well as the alloy composition and the thermo-mechanical treatment of the springs. All springs were mounted on a guiding rod made of an orthodontic steel wire (dimension: 0.016" x 0.022"), were compressed to a maximum extent and then relieved. Force/compression characteristics were measured at ambient temperatures of 27 degrees C, 37 degrees C and 47 degrees C. Three specimens were taken from each individual compression spring of a certain manufacturer and batch to check for constant material behaviour. A possible influence of sterilization on the mechanical properties of the compression springs was studied by autoclaving one spring of each manufacturer five times (6 minutes at 134 degrees C) and subsequently performing a force/deflection measurement. The NiTi compression springs were classified into three groups and covered a broad range of orthodontic forces between 0.5 N and 3.5 N. The width of the superelastic plateaus of the different NiTi coil springs reached from 0% to 66% of relative compression. An increase in the application temperature from 27 degrees C to 47 degrees C caused a rise in the height and a shortening of the width of the superelastic plateau. The resultant change in plateau force was as high as 0.4 N to 0.9 N, depending on the spring type investigated, the width of the plateaus was shortened by 4.0% to 15% of relative compression. All compression springs investigated displayed constant material behaviour within a certain batch. However, differences from one batch to another had a high level of significance. Forces on the plateau varied from one batch to the other by about +/-18%. An influence of sterilization on the force/compression behaviour could not be proved. Consequently, springs made of superelastic NiTi alloys cover a broad field of application with predefined and nearly constant force levels. PMID:10426512

A series of investigations is being conducted to examine the applicability of visible light-cured resins to orthodontics. The experimental vehicle is the Hawley retainer, which is made from autopolymerized (AP), heat-cured (HC), thermoplastic Biocryl 2 (BC), and Traid visible light-cured (VLC) resins. In all physical property testing, it was found that VLC resins met or exceeded required values as established by ADA Specification No. 12 for denture base polymers. In vitro bacterial adherence studies showed that more organisms adhered to heat-cured specimens than to the other specimens. In vivo studies using split-palate Hawley retainers demonstrated slightly less bacterial adherence to BC than to the other resins. Scanning electron microscopy (SEM) observations have shown the BC surface to be the smoothest, although surface chemistry also seems important. None of the materials being tested appears to cause any significant change in the subjacent subgingival bacterial flora. There was no adverse tissue reaction under any of the materials when observed clinically. Manipulation characteristics and time of fabrication appear to be dependent on the depth of the palate and the skill of the operator. PMID:3166329

Abstract in english OBJECTIVES: Natural latex does not fall into the category of materials known to be entirely inoffensive. The purpose of this in vitro study was to test the hypothesis that there is no difference in the cytotoxicity between elastics of different colors and those from different manufacturers. MATERIAL AND METHODS: Different latex intraoral elastics of different colors (5/16 = 7.9 mm, mean load) were compared. The sample was divided into 7 groups of 24 elastics each: Group T (more) (TP Orthodontics, natural latex elastics, control); Groups U1, U2, U3, U4, U5 and U6 (Uniden, natural latex elastics and colored elastics, namely, green, pink, yellow, red and purple, respectively). Cytotoxicity assays were performed by using cell culture medium containing epithelioid-type cells (Hep-2 line) derived from human laryngeal carcinoma. The cytotoxicity was evaluated by using the "dye-uptake" test, which was employed at two different moments (0 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey's test (p

Nickel titanium shape memory alloys (NiTi) are useful materials in orthopedics and orthodontics due to their unique super-elasticity and shape memory effects. However, the problem associated with the release of harmful Ni ions to human tissues and fluids has been raising safety concern. Hence, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. We have conducted acetylene, nitrogen and oxygen plasma immersion ion implantation (PIII) into NiTi alloys in an attempt to improve the surface properties. All the implanted and annealed samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. Besides, the implanted layers are mechanically stronger than the substrate underneath. XPS analyses disclose that the layer formed by C2H2 PIII is composed of mainly TiCx with increasing Ti to C concentration ratios towards the bulk. The nitrogen PIII layer is observed to be TiN, whereas the oxygen PIII layer is composed of oxides of Ti4+, Ti3+ and Ti2+.

Titanium and its alloys have many applications in dentistry, being used in orthodontics, endodontics, prosthetics and implantology. But the use in the biomedical field depends on its biocompatibility, as the Council Directive 93/42/EEC of 14 June 1993 concerning medical devices has established. The aim of this study was to investigate the cytotoxicity and genotoxicity of a commercial titanium/aluminium/vanadium alloy (Ti-6Al-4V) developed by an innovative sand-blast process with aluminium oxide, and nitric-acid passivation. This procedure created a material with an average surface roughness of 1.73±0.16?m with applications in dental implants. International Organization for Standardization (ISO) procedures 7405:2008 and 10993-5:2009 were used to perform the cytotoxicity tests, and bacterial and cell-mutation assays to evaluate genotoxicity. The results show that this titanium alloy (Ti-6Al-4V) was neither cytotoxic nor genotoxic in any of the tests performed. It can be concluded that this new Ti-6Al-4V material with the roughness characteristics specified shows good biocompatibility and can be considered of choice in dental implantology. PMID:20615479

Abstract in portuguese OBJETIVO: objetivou-se com esse trabalho avaliar, em um estudo realizado in vitro, a resistência ao cisalhamento de braquetes metálicos ortodônticos colados pelas técnicas direta e indireta. MÉTODOS: foram utilizados 30 dentes pré-molares superiores humanos hígidos. Os dentes foram divididos em três grupos de 10 dentes: Grupo I - colagem indireta com sistema Sondhi Rapid-Set (3M/Unitek); Grupo II - colagem indireta com sistema Transbond XT (3M/Unitek); e Grupo III (more) - colagem direta com sistema Transbond XT (3M/Unitek). Após realização das colagens e confecção dos corpos de prova, esses foram submetidos ao teste de cisalhamento em uma máquina universal de ensaios da marca comercial EMIC, modelo DL-500. Foram aplicados os testes de Kolmogorov-Smirnov, para verificar se os dados tinham uma distribuição normal, e o teste de Bartlett, para verificar se existia igualdade entre as variâncias. Aplicou-se a análise de variância de um fator e, posteriormente, o teste de Tukey para o contraste pareado de médias. O nível de significância foi de 5%. RESULTADOS: os resultados do Grupo I foram 67,6N e 5,9MPa; do Grupo II foram 68,9N e 6,1MPa; e do Grupo III (controle), 92,5N e 8,1MPa. CONCLUSÃO: pode-se concluir que tanto para os valores em Newtons (N) como para os valores em Megapascal (MPa), a média do Grupo III foi significativamente maior em relação aos Grupos I e II. Já para as médias onde a técnica indireta foi usada (Grupos I e II), não houve diferenças estatisticamente significativas. Abstract in english OBJECTIVE: This in vitro study was designed to evaluate the shear bond strength (SBS) of orthodontic metal brackets bonded by direct and indirect techniques. METHODS: Thirty healthy human maxillary premolar teeth were used. The teeth were divided into three groups of 10 teeth each: Group I - indirect bonding with SondhiTM Rapid-Set system (3M/Unitek), Group II - indirect bonding with TransbondTM XT adhesive system (3M/Unitek) and Group III - direct bonding with TransbondT (more) M XT adhesive system (3M/Unitek). After bonding and obtaining the specimens for the study, the specimens were subjected to SBS testing in a universal testing machine (Emic, model DL-500). The Kolmogorov-Smirnov test was applied to ascertain that the data had a normal distribution and the Bartlett test to check whether there was homogeneity of variance. One-factor analysis of variance was performed and, subsequently, Tukey's test for paired means. A 5% significance level was adopted. RESULTS: The results of Group I were 67.6 (N) and 5.9 (MPa); Group II, 68.9 (N) and 6.1 (MPa) and Group III (control), 92.5 (N) and 8.1 (MPa). CONCLUSION: It can therefore be concluded that the means for Group III were significantly higher compared with Groups I and II in both Newton (N) and Megapascal (MPa) values. The means attained by the indirect bonding technique used in Groups I and II, however, exhibited no statistically significant differences.

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We derive equations of motion for the dynamics of anisotropic particles directly from the dissipative Vlasov kinetic equations, with the dissipation given by the double bracket approach (Double Bracket Vlasov, or DBV). The moments of the DBV equation lead to a nonlocal form of Darcy's law for the mass density. Next, kinetic equations for particles with anisotropic interaction are considered and also cast into the DBV form. The moment dynamics for these double bracket kinetic equations is expressed as Lie-Darcy continuum equations for densities of mass and orientation. We also show how to obtain a Smoluchowski model from a cold plasma-like moment closure of DBV. Thus, the double bracket kinetic framework serves as a unifying method for deriving different types of dynamics, from density--orientation to Smoluchowski equations. Extensions for more general physical systems are also discussed.

The study demonstrates the possibility of using Tm:YAP laser radiation for the removing ceramic brackets. The amount of enamel loss and residual resin on teeth has been evaluated. A diode-pumped Tm:YAP microchip laser generating at wavelength 1.9 ?m was used for the debonding process. The transmission and absorption measurement of the basic elements - bracket, adhesive resin, and enamel was analyzed to explain the source of the heat and bracket debonding. Quantitative measurements are made for visualizing enamel surface before and after a self-ligating bonding technique. Temperature rise observation during the debonding procedure - from 0.5 to 2 W power - has improved the accuracy of assessment. The results were evaluated by CCD camera and scanning electron microscope. From the measurements it is possible to conclude that continuously running small diode pumped Tm:YAP microchip laser having output power 1W can remove the ceramic bracket without enamel iatrogenic damage.

In this paper the canonical Dirac formalism for time-dependent constrained Hamiltonian systems is globalized. A time-dependent Dirac bracket which reduces to the usual one for time-independent systems is introduced. (author)

A single pole mounting solar panel assembly comprising at least one solar panel and upper and lower brackets fixed to the panel and to the pole, the upper bracket having a first flange means for mating with the pole and a first base plate fixed to the panel, the lower bracket means having a second flange means fixed to and encompassing a substantial portion of the circumference of the pole and a plane surface which extends out to the panel, the width of the plane surface varying from about the width of the pole to the width of the panel, the flange means for the lower bracket having upstanding side means extending longitudinally of the plane surface for about the full length of the plane surface, the side means and plane surface terminating at a second base plate fixed to the panel.

The torque moment generated by third-order bends is important for tooth movement. The purpose of this study was to measure the torque moment that can be delivered by various archwire and bracket combinations at the targeted tooth. Stainless steel (SS) upper brackets with 0.018 and 0.022 inch slots, two sizes of nickel-titanium (Ni-Ti) alloy wires, and three sizes of SS wires for each bracket were used. The wire was ligated with elastics or wire. The torque moment delivered by the various archwire-bracket-ligation combinations was measured using a torque gauge. Statistical analysis was undertaken using analysis of variance (multiple comparison tests and post hoc using Tukey's honestly significant difference test. The torque moment increased as the degree of torque and wire size increased. T...

In this note we discuss some formal properties of universal linearization operator, relate this to brackets of non-linear differential operators and discuss application to the calculus of auxiliary integrals, used in compatibility reductions of PDEs.