Lubricating conditions: effects on friction between orthodontic brackets and archwires with different cross-sections

Abstract Objective: This study investigated the effect of the condition of lubrication on the friction between brackets and NiTi archwires of different rounded cross-sections. Methods: Brackets (Roth, GAC) were affixed to a device connected to a universal testing machine into which segments of archwire were placed (NiTi, Nitinol, GAC) with cross-sections of 0.012-in, 0.016-in and 0.020-in. Once the wire was in the bracket slot, the following lubricants were applied: human saliva (HS: positive control), distilled water (DI), mucin-based (MUC) or carboxymethylcellulose-based (CMC) artificial saliva. In the negative control group, no lubricant was used. The combination between the wire cross-sections and the lubrication condition generated 15 groups with 15 samples each. Data were submitted to two-way analysis of variance and Tukey's test. Results: There was no significant interaction between the wire cross-section and the condition of lubrication (p= 0.901). Irrespective of whether lubricants were used or not, there was a significant increase in friction with an increase in the cross-section of the wire (p< 0.001). For any wire, the group tested in the presence of MUC was not different from that in which HS was applied. On the other hand, when the application of lubricants was suppressed, significantly higher friction values were observed. The CMC group and the DI group demonstrated intermediate behavior. Conclusions: Friction increased with the increase of the cross-section of the NiTi archwire, but regardless of the archwire, friction with MUC artificial saliva was similar to that of HS and lower than in dry conditions.

Resumo Objetivo: este estudo investigou o efeito das condições de lubrificação no atrito entre braquetes e fios de NiTi de diferentes secções transversais. Métodos: os braquetes (Roth, GAC) foram fixados a um dispositivo conectado a uma máquina de ensaio universal, que recebeu segmentos de fio de NiTi (Nitinol, GAC) com secções de 0,012"; 0,016" ou 0,020". Após o fio ter sido instalado no slot do braquete, aplicou-se um dos seguintes lubrificantes: saliva humana (SH: controle positivo), água destilada (AD) ou saliva artificial à base de mucina (MUC) ou de carboximetilcelulose (CMC). No grupo controle negativo, nenhum lubrificante foi utilizado. As combinações entre as secções dos fios e as condições de lubrificação geraram 15 grupos, com 15 amostras cada. Os dados foram submetidos à análise de variância a dois critérios e ao teste de Tukey. Resultados: não houve interação significativa entre a secção do fio e a condição de lubrificação (p = 0,901). Independentemente de ter sido utilizado ou não lubrificante, observou-se elevação significativa do atrito com o aumento da secção transversal do fio (p < 0,001). Para qualquer um dos fios, o grupo testado na presença de MUC não diferiu daquele em que se aplicou SH. Por outro lado, quando suprimiu-se os lubrificantes, constatou-se atrito significativamente mais elevado. Os grupos CMC e AD demonstraram comportamento intermediário. Conclusões: o atrito se elevou com o aumento da secção transversal dos fios de NiTi, mas a despeito do fio, o atrito com a saliva à base de MUC foi similar àquele com a SH e menor do que sob condição a seco.

Evaluation of conformity of preformed orthodontic archwires and dental arch form

ABSTRACT Introduction: The alterations in the arch form during treatment are dictated by the dimensions of the archwires. Objective: This study aimed to determine the mean arch dimensions of a sample of Pakistani subjects and to evaluate the conformity of preformed archwires with mandibular arch form. Methods: The dental records of 1,500 adult subjects were evaluated. The mandibular casts of 42 subjects (males = females = 21) with balanced facial profile, Class I occlusion, ideal overjet and overbite were included. Brackets were bonded on all teeth. Arch dimensions were evaluated at canines, first premolars, second premolars, first and second molars, with digital vernier calipers. The arch widths at the level of aforementioned teeth were evaluated on the digitized archwires, using the mean arch depths of the subjects. Results: In males, the archwires were found to be wider at canines and premolars, and significantly narrower at first (p< 0.001, 95% CI = 2.03 - 5.74) and second molars (p< 0.001, 95% CI = 2.29 - 7.73) as compared to the arch dimensions of the mandibular casts. In females, the archwires were significantly narrower at canines (p< 0.001, 95% CI = 1.4 - 3.97), and first (p= 0.02, 95% CI = 0.402 - 4.41) and second molars (p< 0.001, 95% CI = 1.76 - 6.13). Conclusion: No single commercially available archwires evaluated in the present study conformed to the arch dimensions of our subjects. Utilization of the currently available archwires may result in unwarranted modification of arch form, which may lead to unstable post-treatment teeth position.

RESUMO Introdução: as alterações no formato da arcada dentária durante o tratamento são ditadas pelas dimensões do arco ortodôntico. Objetivo: o presente estudo teve como objetivos determinar a dimensão média das arcadas dentárias de pacientes paquistaneses e avaliar a conformidade entre diferentes arcos ortodônticos pré-fabricados e o formato da arcada inferior. Métodos: os registros odontológicos de 1.500 pacientes adultos foram analisados e, desses, foram selecionados modelos de gesso de 42 pacientes (21 de cada sexo, masculino e feminino) com perfil facial equilibrado, Classe I de Angle, sobressaliência e sobremordida adequadas. Foram, então, colados braquetes ortodônticos em todos os dentes. Utilizando um paquímetro digital, as dimensões das arcadas foram avaliadas nos seguintes dentes: caninos, primeiros pré-molares, segundos pré-molares, primeiros e segundos molares. Utilizando-se a profundidade média das arcadas dos pacientes, as larguras das arcadas, no nível dos dentes acima mencionados, foram comparadas aos arcos ortodônticos digitalizados. Resultados: nos homens, a largura do arco ortodôntico, em comparação às dimensões dos modelos de gesso inferiores, foi maior nos caninos e pré-molares e significativamente menor nos primeiros molares (p< 0,001, IC 95% = 2,03 - 5,74) e segundos molares (p< 0,001, IC 95% = 2,29 - 7,73). Nas mulheres, os arcos ortodônticos foram significativamente mais estreitos nos caninos (p< 0,001, IC 95% = 1,4 - 3,97), primeiros molares (p= 0,02, IC 95% = 0,402 - 4,41) e segundos molares (p< 0,001, IC 95% = 1,76 - 6,13). Conclusão: nenhum dos arcos ortodônticos comercialmente disponíveis avaliados no presente estudo esteve em conformidade com as dimensões das arcadas dos pacientes da amostra. O uso dos arcos ortodônticos atualmente disponíveis pode resultar em modificações indesejáveis no formato da arcada, e pode levar à instabilidade na posição dos dentes após o tratamento.

A comparative analysis of the frictional resistance of esthetic orthodontic wires / Avaliação do atrito de fios ortodônticos estéticos

Abstract Introduction The orthodontic movement is directly influenced by the ability of orthodontic wires to slide through brackets and tubes. Therefore, the main concern during orthodontic movement corresponds to the frictional forces generated at the bracket-orthodontic wire interface. Objective This study aimed to evaluate the frictional resistance of esthetic orthodontic wires. Material and method Fifty test brackets were obtained and divided into five groups (n = 10) based on the type of rectangular orthodontic wire, as follows: conventional metallic wire (Morelli, Brazil) (G1, control group) and esthetic wires (G2, Ortho Organizer; G3, Tecnident; G4, Trianeiro; and G5, TP Orthodontics). The following materials and conditions were used: 0.019 x 0.025-inch wires, ceramic brackets with edgewise prescription, torque and/or angulation of 0°, and 0.022 x 0.028-inch slots. The specimens were tested for their tensile strength using an Instron universal test machine at a speed of 1.0 mm / min and a load cell of 500N. The tensile strength data were analyzed by one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test, with a 5% significance level. Result The frictional resistance (N) of the metallic orthodontic wire (8.07 ± 0.43) was significantly higher than that of the esthetic wires: Ortho Organizer (4.01 ± 0.25), Tecnident (3.87 ± 0.31), Trianeiro (4.47 ± 0.26) and TP Orthodontics (4.49 ± 0.30) (p <0.05), with no significant difference between them (p> 0.05). Conclusion To conclude, the esthetic orthodontic wires tested herein showed less frictional resistance as compared to the conventional metallic wire.

Resumo Introdução O movimento ortodôntico bem sucedido está diretamente relacionado com a capacidade de os fios ortodônticos deslizarem sobre os bráquetes e tubos ortodônticos. Portanto, durante a movimentação ortodôntica a principal preocupação está diretamente ligada a fricção entre o suporte e o fio. Objetivo O objetivo deste estudo foi avaliar a influência de fios ortodônticos estéticos na resistência ao atrito. Material e método Foram utilizados 50 bráquetes-teste divididos em 5 grupos, de acordo com o fio retangular (n=10): G1 - grupo controle: fio metálico convencional (Morelli, Brasil) e fios estéticos (G2 - Ortho Organizer; G3 - Tecnident; G4 - Trianeiro; e, G5 - TP Orthodontics). Todos os fios apresentavam 0,019 x 0,025 polegadas e o bráquete era cerâmico, prescrição Edgewis e, torque e/ou angulação 0° e, canaleta 0,022 x 0,028 polegadas. O teste de resistência ao atrito sob força de tração foi realizado em uma máquina de ensaio universal Instron à velocidade de 1,0 mm/min e célula de carga de 500N. Os dados de resistência ao atrito foram submetidos à análise de variância (ANOVA) um fator e ao Teste de Tukey com nível de significância de 5%. Resultado O atrito (N) do fio metálico (8,07±0,43) foi significativamente maior que os fios ortodônticos estéticos: Ortho Organizer (4,01±0,25), Tecnident (3,871±0,31), Trident (4,47±0,26) e, TP (4,49±0,30) (p<0,05). Nenhuma diferença estatisticamente significativa foi observada entre os fios estéticos (p>0,05). Conclusão Conclui-se que os fios ortodônticos estéticos apresentam menor resistência ao atrito quando comparado ao fio metálico.

Intrusion of the extruded maxillary central incisor using skeletal anchorage system and unilateral segmental intrusion arch

Patients who have a moderate periodontitis with pathologic tooth migration of maxillary incisors, it is necessary not only periodontal treatment for reduce periodontal inflammation, but also orthodontic treatment to teeth repositioning. For orthodontic treatment, it is necessary to apply less force and careful considerations of the center of resistance of the tooth and optimal force of tooth movement. At this time, the segmental arch applied only to the target teeth, is more effective and predictable, because applied force and direction can be controlled. In addition, to design the orthodontic appliance that can prevent the unwanted tooth movement that used as an anchorage is important. In recent years, various types of skeletal anchorage system have been used for preventing loss of the anchorage. We reported the patient who had extruded maxillary central incisor due to pathologic tooth migration, treated by a successful periodontal-orthodontic multidisciplinary treatment using an orthodontic appliance designed to apply less traumatic force and reduce an anchorage loss.

Welding strength of NiTi wires

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

RESUMO Objetivo: identificar a potência mais adequada para solda elétrica em três marcas comerciais de fios de níquel-titânio (NiTi). Métodos: noventa pares de fios ortodônticos de NiTi, de dimensões 0,018" e 0,017" × 0,025'', foram soldados por resistência elétrica e distribuídos em três grupos: GI (Orthometric, Marília, São Paulo, Brasil), GII (3M, São José do Rio Preto, São Paulo, Brasil) e GIII (GAC, Yorque, Pensilvânia, Estados Unidos). Cada grupo foi dividido em subgrupos de cinco pares de fios soldados com diferentes níveis de potência. Nos GI e GII, os fios foram soldados com níveis de potência de 2.5, 3, 3.5, 4, 4.5 e 5; enquanto no GIII as potências utilizadas foram de 2.5, 3, 3.5 e 4. Os pares de fios foram submetidos a um teste de tração até sua ruptura, com registro das forças máximas. Análises de variância (ANOVA) e testes post-hoc foram realizados para determinar qual subgrupo, dentro de cada grupo, obteve a maior força de resistência. Resultados: a potência 2.5 exibiu a menor resistência à ruptura para todos os grupos (43,75 N para o GI; 28,41 N para o GII e 47,57 N para o GIII). A potência 4 mostrou maior resistência à ruptura nos GI e GII (97,90 N e 99,61 N, respectivamente), enquanto no GIII (79,28 N) foi a potência 3.5. Conclusões: os níveis de potência mais adequados variaram para as marcas comerciais, sendo identificados como 4 para Orthometric e 3M, e 3.5 para GAC.

Evaluation of cytotoxicity of electroplated stainless steel orthodontic wire / 대한치과교정학회지

The purpose of this study was to examine the cytotoxicity of orthodontic wire which had an increased diameter through electroplating, and to evaluate its possible clinical applications. First, nickel plating was carried out on the commercially available stainless steel wire using an electroplating technique. For the comparison of the electroplated wire with ready made stainless steel wire and titanium or copper, each wire was incubated for 72 hours in a medium. The release of the metal ion was measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrophotometer). Balb/c 3T3 mouse fibroblast was put on a microplate and placed in an incubated medium of 75%, 50%, and 20% dilation. An MTT analysis was used to compare with the medium only. The change in absorbency value of each wire group and the difference of absorbency value according to the change of dilution was measured. The results of ICP-AES analysis showed that great amount nickel ion was isolated from electroplated orthodontic wires and great amount copper ion was isolated from copper. The results of the MTT analysis showed that there was no difference in the absorbency value of titanium at any dilution. However, the electroplated wires (p < 0.001), the stainless steel wires (p < 0.05) and the copper (p < 0.001) were statistically significantly lower than those of medium only at all dilutions. Assessment as per ISO 10993, part 5, showed that electroplated wire was alloted to "moderate cytotoxic", the titanium and stainless steel wire were "non-cytotoxic". The results of this study indicate that the electroplated orthodontic wires need additional efforts to decrease cytotoxicity for their clinical applications.

An experimental study on diameter increase of orthodontic wire by electroplating / 대한치과교정학회지

The purpose of this study was to evaluate the possibile clinical application of electroplating to increase diameter of an orthodontic wire, through examining the change of physical properties. The diameter of stainless steel orthodontic wire was increased from 0.016 inch to 0.018 inch by electroplating in a bath of nickel sulfate 100g/L, nickel chloride 60g/L, boric acid 30g/L, and sodium chloride 50g/L, under the conditions of 1.7V, 25~29degrees C, and 3.1~3.3pH. During the electroplating, the rate of diameter increase was measured every minute. To investigate uniformity, the diameter was measured at three different locations of each wire specimen after electroplating. An X-ray diffraction test was performed to analyze the nature of the electroplated metal. Following heat treatment to improve adhesion between the wire and electroplated metal, a three-point bending test was conducted to compare stiffness, yield strength, and ultimate strength among four wire groups; 0.016 inch, electroplated 016, electroplated and heat-treated 016, and 0.018 inch wires. Through the comparison of each wire group, following results were obtained. 1. In the load-deflection graph, the curve of the electroplated group was placed between that of the 0.016 inch group and the 0.018 inch group, and the curve was closer to the 0.018 inch group by heat treatment. 2. In the electroplated and heat-treated 016 wire group, the values of stiffness, yield strength and ultimate strength showed higher tendency than in the original 0.016 inch group. Stiffness and ultimate strength showed statistically significant differences between two groups. 3. Stiffness, yield strength, and ultimate strength of electroplated wire presented lower values than those of 0.018 inch wire group. 4. Stiffness, yield strength, and ultimate strength of electroplated and heat-treated wire showed higher tendency than those of electroplated wire group, and ultimate strength showed statistically significant difference between two groups. 5. After electroplating, the difference in diameter between the three locations was within 0.1~0.3% variation, and showed no statistical significance.

An experimental study of dynamic frictional resistance between orthodontic bracket and arch wire / 대한치과교정학회지

This investigation was designed to determine the effects of wire size, bracket width and the number of bracket on bracket-wire dynamic frictional resistance during simulating arch wire-guided tooth movement in vitro. For simulation of an arch wire-guided tooth movement, we simulated tooth, periodontal ligament and cancellous bone. Maxillary premolar and 1st molar were simulated as real sized resin teeth, the simulated resin teeth which its root was coated by polyether impression material which its elastic modulus is similar to periodontal ligament were embedded in steel housing with inlay wax which its elastic modulus is similar to cancellous bone. Stainless steel wires in four wire size (0.016, 0.018, 0.016 x 0.022, 0.019 x 0.025 inch) were examined with respect to three (stainless steel) bracket widths (2.4, 3.0, 4.3mm) and the number of medium bracket(one, two, three) included in the experimental assembly under dry condition. The wires were ligated into the brackets with elastomeric module. The results were as follows : 1. In all the brackets, frictional resistance increased with increase in wire size. But, statistically similar levels of frictional resistance were observed between 0.018 inch and 0.016 x 0.022 inch wires in narrow bracket and also between 0.016 inch and 0.018 inch wire in wide backet. 2. The frictional forces produced by 0.016 inch wire were statistically similar levels in all the brackets. In 0.018 inch round wire, wide bracket was associated with lower amounts of friction than both narrow and medium brackets. In 0.016 x 0.022, 0.019 x 0.025 inch rectangular wire, wide bracket produced larger friction than both narrow and medium brackets. In all the wires, narrow and medium bracket demonstrated no statistical difference in levels of frictional resistance. 3. Frictional resistance increased with increase in number of medium bracket. 0.016 inch round wire demonstrated the greatest increment in frictional resistance, followed by 0.019 x 0.025, 0.016 x 0.022 inch rectangular wire which were similar level in increment of frictional resistance, 0.018 inch wire demonstrated the least increment. The increments of frictional resistance were not constantly direct proportion to number of bracket.

Caracterização química, metalúrgica e estudo das propriedades mecânicas dos fios ortodônticos de titânio-molibdênio TMA / Chemical, metallic characterization and study of the mechanical properties of the titanium-molibidenium orthodontic wire TMA

Essa pesquisa tem por objetivo a caracterização química, metalográfica e estudo das propriedades mecânicas de fios ortodônticos de titâniomolibdênio - TMA. As amostras foram submetidas a análise química e metalográfica, empregando-se microscopia eletrônica de varredura ­ MEV com espectroscopia por dispersão de energia de raios X ­ EDX e mapeamento elementar, determinando-se uma análise semi quantitativa e qualitativa dos elementos (Ti, Mo, Zr e Sn) presentes na amostra. Para se avaliar as propriedades mecânicas foram realizados ensaios de tração até a ruptura dos corpos-de-prova, análise da fratura e ensaios de dureza. Os resultados encontrados foram comparados com os dos fios de aço inoxidável, por serem considerados padrão para a Odontologia. Baseando-se na análise dos dados experimentais, constatou-se que as ligas de TMA em relação às ligas de aço, apresentam resiliência semelhante com maior flexibilidade devido a menor rigidez e baixo módulo de elasticidade. Finalmente, pode-se apresentar subsídios para a seleção de ligas metálicas adequadas as necessidades de cada fase do tratamento ortodôntico

The aim of this research is the chemical, metalographic characterization and study of the mechanical properties of the titanium-molibidenium orthodontic wire ­ TMA. The samples were submitted to chemical and metalographic analyses, using na eletronic scanning microscope (MEV) witth spectroscopy by X-ray energy dispersion (EDX) and elementar maping, determinating a semi-qualitative and quantitative analyses of the elements (Ti, Mo, Zr and Sn) present in the sample. To evaluate the mechanical properties it were performed tensile test till the rupture of the body samples frature analyses and hardness test. The found results were compared to the two still wire, because they were considered to be standard for dentistry. Based on the analyses of these experimental data we could observe that the TMA alloy is compared to the steel alloy, presenting similar resistence with higher flexibility due to lower hardness and low elasticity module. At last we were able to present subsides for the selection of the best metal alloy required to the necessity of each Orthodontic treatment phase

The frictional resistance of tin ion-plated Co-Cr orthodontic wire / 대한치과교정학회지

The effectiveness of TiN ion-plating was examined with TiN ion-plated Co-Cr wires(016", 016"X.022") on three different types of bracket(TiN ion-plated metal bracket, ceramic bracket and plastic bracket). Maximum static frictional forces and characteristic curves obtained from the frictional characteristic graph, were compared and surface roughness of wires and bracket slots before and after friction experiment was observed by SEM. The obtained results were as follows. · The frictional forces of TiN ion-plated wires were significantly lower than those of non ion-plated wires(P<0.O5 ).· On the effect of wire shape, the frictional forces of round wires were significantly lower than those of rectangular wires(P<0.05). · As the result of the SEM observation on the wires and bracket slots after the friction experiment, the surface of non ion-plated wires was rougher than that of TiN ion-plated ones. · The difference between the static frictional forces and the kinetic frictional forces was not significant in case of the TiN ion-plated round wires, but the static frictional forces were a little higher than the kinetic frictional forces in the TiN ion-plated rectangular wires. · The static frictional forces were much higher than the kinetic frictional forces in the case of non ion-plated wires.

An experimental study on the cytotoxicity of orthodontic wires / 대한치과교정학회지

This study was undertaken to investigate the cytotoxicity of orthodontic wires after doing various treatments to the wires. 018x025 inch Stainless steel(A) and Co-Cr(B) wires were used and each of them were divided into 4 groups. A-1 and B-1 groups were as received state, and A-2 and B-2 groups were heat treated. A-3 and B-3 groups were electropolished after heat treatment, and A-4 and B-4 groups were soldered with Ag-solder. Each group had 3 wires and these were sterilized with Ethylene Oxide gas. We used human gingival fibroblast cell culture and agar overlay technique to investigate the cytotoxicity of each group of wires. The cytotoxicity of wire was assessed using reaction index (zone index / lysis index). The findings of this study were as follows: 1. Both of the stainless steel wire and Co-Cr wire showed no cytotoxicity in as received state. 2. Heat treatment or electropolishing of the wires had no effect on the cytotoxicity of the wires. 3. Soldered stainless steel wires showed a little wider zone of discoloration than soldered Co-Cr wires, but the zone index and cytotoxicitytreaction index) was not different. 4. Soldered wires showed moderate cytotoxicity in both of the wires.