Comparação entre os implantes dentários e implantes ortopédicos / Comparison between dental implants and orthopedic implants ­ literature review

Objetivo: revisar as semelhanças e diferenças entre os implantes dentários osseointegráveis e os implantes ortopédicos. Material e métodos: apesar da escassez de dados, foram construídos quatro tópicos: 1) materiais dos implantes osseointegráveis e ortopédicos; 2) técnicas cirúrgicas na Odontologia e na Ortopedia; 3) possíveis causas e efeitos do aquecimento; e 4) análise do insucesso dos implantes nas duas áreas. Resultados: 1) nenhum dos biomateriais metálicos usados na Ortopedia apresenta osseointegração conforme o conceito atualmente usado na Odontologia e, sob alto carregamento, estas ligas estão submetidas ao stress shielding em função do seu módulo de elasticidade ser muito acima do osso; 2) na Implantodontia, a estabilidade primária é fundamental e os procedimentos são mais delicados, enquanto na Ortopedia os implantes são cimentados (estabilizados) e os procedimentos ortopédicos são mais agressivos, estando entre os maiores índices de perdas advindas de complicações pós-cirúrgicas; 3) as condições de realização da cirurgia para inserção de implantes ortopédicos são mais críticas em relação aos dentários, devido ao maior volume de osso que é removido, maiores dimensões da prótese, menor vascularização do local e ausência de irrigação do meio durante a cirurgia, com temperaturas médias (70oC) acima do que se observa na Implantodontia odontológica (43oC); 4) a propensão ao insucesso nos implantes ortopédicos parece maior pela chance de carregamento 3-5 vezes maior em áreas corporais (quadril e joelho) que sustentam o peso do corpo. Conclusão: melhorias contínuas nos materiais, procedimentos e treinamento fornecerão taxa menor de reposição de implantes dentários e, especialmente, dos implantes ortopédicos.

Objective: to review the similarities and differences between osseointegrated dental and orthopedic implants. Material and methods: besides data paucity, four topics were created: 1) materials for osseointegrated and orthopedic implants; 2) surgical techniques in Dentistry and Orthopedics; 3) possible causes and effects of heating; and 4) failures analyses in both areas. Results: 1) none of the metallic biomaterials for Orthopedics present osseointegration according to the concept developed for dentistry and, under high loading, alloys are subjected to stress shielding due to their elastic moduli being higher than the bone; 2) for implant dentistry, primary stability is fundamental and the procedures are more delicate, whereas in Orthopedics the implants are cemented (stabilized) and the procedures have a more aggressive nature, within the highest levels of post-surgical complications; 3) surgical conditions for Orthopedics are more critical than in the dental field, due to a greater bone volume, prosthesis size, less local vascularization and lack of irrigation, with mean temperatures (70oC) well-above compared to the implant dentistry (43oC); 4) the failure of orthopedic implants seems higher due to the 3-5 times chance of loading at corporal bearing structures (hips and knees). Conclusion: continuous improvement on materials, procedures, and training will provide less replacement rates for dental implants and specially for orthopedic devices.

Metodologias de análise da composição química da superfície dos implantes / Investigational methods for chemical analysis of dental implant surfaces

Os trabalhos disponíveis na literatura apresentam resultados divergentes da análise da composição química da superfície dos implantes comerciais, por empregarem diferentes técnicas. Considerando que esta propriedade influencia na osseointegração, os cirurgiões-dentistas precisam ter confiança nas informações obtidas na literatura e nas fornecidas pelos fabricantes. Quando a análise da superfície é feita de modo correto, é possível identificar diferenças positivas e negativas na composição química entre os implantes comerciais. O objetivo do presente trabalho foi apresentar resultados das análises da composição química da superfície de implantes comerciais produzidos no Brasil e importados, e sugerir procedimentos para estas análises. Os resultados mostraram que os implantes jateados são os que possuem maior probabilidade de terem contaminantes na superfície, e a análise da composição química usando EDS (energy dispersive x-ray spectroscopy) é a técnica que apresenta menor confiabilidade.

Published papers have shown divergent results regarding the chemical composition of commercially available dental implant surfaces due to different analytical techniques. Considering that this can infl uence the osseointegration process, dental practitioners need to be confi dent on literature and fabricant information. When surface analysis is correctly employed, it is possible to identify positive and negative aspects on several chemical characteristics. The aim of this paper is to present the outcomes of national and international dental implant surfaces and to suggest procedures accordingly. It was demonstrated that sandblasted surfaces are more prone to have contaminants, and that energy dispersive X-ray spectroscopy (EDS) is the technique presenting low reliability levels.

Seleção da superfície dos implantes com base no tipo de osso / Selection of implant surface according to bone type

No início da Implantodontia, as próteses implantossuportadas eram múltiplas, apoiadas em implantes conectados entre si (esplintados), e o protocolo cirúrgico era o de 2 estágios, mas mesmo assim, os índices de sucesso eram baixos (83,3%). Atualmente, os implantes são inseridos em condições mais críticas, as próteses são unitárias e os índices de sucesso são em torno de 98%. Para o aumento do índice de sucesso foram realizadas alterações nas formas dos implantes, mudanças das técnicas cirúrgicas e o tratamento da superfície contribuíram significativamente. No entanto, persistem casos de falha do implante devido à indicação inadequada do tipo de implante para o osso do local de instalação. Neste trabalho são apresentadas as principais superfícies dos implantes e suas indicações para os diferentes tipos de osso (AU)

At the beginning of Implantology, implants were connected to each other and a 2-stage technique was the used surgical protocol. But, the success rate of osseointegrated implant was low (83.3%). Currently, implants are inserted in increasingly critical conditions and the prostheses are unitary while the success rate is of approximately 98%. The significant increase in the success rate was achieved through changes made in implant design, surgical techniques and the surface treatment. However, there are still cases of failure due to a mismatch between the indicated implant and the type of bone in the installation site. This work presents the main surfaces of dental implants and their indications for different types of bone (AU)

Influence of cortical thickness on the stability of mini-implants with microthreads.

The objective of this study was to assess the influence of cortical thickness and bone density on the insertion torque of a mini-implant (MI) with microthreads. Mini-implants with lengths of 6 and 8 mm in the active part were inserted into synthetic bone blocks (polyurethane resin). The density of these blocks was 20 pounds per cubic foot (pcf), simulating bone marrow, and that of blocks 1, 2, and 3-mm-thick blocks was 40 pcf, simulating cortical bone. Blocks with uniform density of 40 pcf were also used to simulate bone areas of greater density. Insertion torque was quantified with a universal testing machine (EMIC). For both MIs, increasing insertion torque was associated with increasing cortical bone thickness. For the same MI length, significant differences were observed among all assessed groups. The insertion torque of the 6-mm-long MI inserted in a 3-mm-thick cortical bone was equivalent to that of the 8-mm-long MI inserted in a 1-mm-thick cortical bone. MIs inserted in bone blocks of greater density presented insertion torque values almost twice as high as those in other groups. The shorter MI, the lower the insertion torque, and the greater the cortical bone thickness, the greater the insertion torque. To minimize fracture risk, the size of MI should be selected according to the insertion site.

Influence of Screw Length and Bone Thickness on the Stability of Temporary Implants.

The purpose of this work was to study the influence of screw length and bone thickness on the stability of temporary implants. A total of 96 self-drilling temporary screws with two different lengths were inserted into polyurethane blocks (n = 66), bovine femurs (n = 18) and rabbit tibia (n = 12) with different cortical thicknesses (1 to 8 mm). Screws insertion in polyurethane blocks was assisted by a universal testing machine, torque peaks were collected by a digital torquemeter and bone thickness was monitored by micro-CT. The results showed that the insertion torque was significantly increased with the thickness of cortical bone from polyurethane (p < 0.0001), bovine (p = 0.0035) and rabbit (p < 0.05) sources. Cancellous bone improved significantly the mechanical implant stability. Insertion torque and insertion strength was successfully moduled by equations, based on the cortical/cancellous bone behavior. Based on the results, insertion torque and bone strength can be estimate in order to prevent failure of the cortical layer during temporary screw placement. The stability provided by a cortical thickness of 2 or 1 mm coupled to cancellous bone was deemed sufficient for temporary implants stability.

Mechanical properties, surface morphology and stability of a modified commercially pure high strength titanium alloy for dental implants.

OBJECTIVE: Commercially pure titanium (cp Ti) and Ti-6Al-4V (Ti G5) alloy have limitations for biomedical application, due to lower mechanical strength and the possibility of ion release, respectively. The purpose of this work was to compare the properties of a modified cp Ti grade 4 (Ti G4 Hard) with those of available cp Ti and Ti G5 alloys. METHODS: Bars, discs and dental implants made with Ti G2, G4, G5 and G4 Hard were used. Mechanical tests (tension, compression, hardness and torque) and roughness measurements were performed. Clinical trials were used to evaluate the biological behavior of dental implants made with Ti G4 Hard and Ti G4. RESULTS: The results of the mechanical tests showed that the mechanical strength of modified Ti G4 is higher than that of Ti G2, G4 and G5. Scanning electron microscopy analysis showed that modified Ti G4 after etching has better surface morphological features than conventional cp Ti and Ti G5. The clinical performances of Ti G4 and Ti G4 Hard were similar. SIGNIFICANCE: The improvement of the mechanical properties of modified Ti G4 means that Ti G5 can be safely replaced by Ti G4 Hard without compromising the fracture resistance, with the advantage of not releasing toxic ions.

Influence of cortical thickness on the stability of mini-implants with microthreads

The objective of this study was to assess the influence of cortical thickness and bone density on the insertion torque of a mini-implant (MI) with microthreads. Mini-implants with lengths of 6 and 8 mm in the active part were inserted into synthetic bone blocks (polyurethane resin). The density of these blocks was 20 pounds per cubic foot (pcf), simulating bone marrow, and that of blocks 1, 2, and 3-mm-thick blocks was 40 pcf, simulating cortical bone. Blocks with uniform density of 40 pcf were also used to simulate bone areas of greater density. Insertion torque was quantified with a universal testing machine (EMIC). For both MIs, increasing insertion torque was associated with increasing cortical bone thickness. For the same MI length, significant differences were observed among all assessed groups. The insertion torque of the 6-mm-long MI inserted in a 3-mm-thick cortical bone was equivalent to that of the 8-mm-long MI inserted in a 1-mm-thick cortical bone. MIs inserted in bone blocks of greater density presented insertion torque values almost twice as high as those in other groups. The shorter MI, the lower the insertion torque, and the greater the cortical bone thickness, the greater the insertion torque. To minimize fracture risk, the size of MI should be selected according to the insertion site.

Insertion torque versus mechanical resistance of mini-implants inserted in different cortical thickness.

OBJECTIVE: This study aimed to measure insertion torque, tip mechanical resistance to fracture and transmucosal neck of mini-implants (MI) (Conexão Sistemas de PróteseT), as well as to analyze surface morphology. METHODS: Mechanical tests were carried out to measure the insertion torque of MIs in different cortical thicknesses, and tip mechanical resistance to fracture as well as transmucosal neck of MIs. Surface morphology was assessed by scanning electron microscopy (SEM) before and after the mechanical tests. RESULTS: Values of mechanical resistance to fracture (22.14 N.cm and 54.95 N.cm) were higher and statistically different (P < 0.05) from values of insertion torque for 1-mm (7.60 N.cm) and 2-mm (13.27 N.cm) cortical thicknesses. Insertion torque was statistically similar (P > 0.05) to torsional fracture in the tip of MI (22.14 N.cm) when 3 mm cortical thickness (16.11 N.cm) and dense bone (23.95 N.cm) were used. Torsional fracture of the transmucosal neck (54.95 N.cm) was higher and statistically different (P < 0.05) from insertion torsional strength in all tested situations. SEM analysis showed that the MIs had the same smooth surface when received from the manufacturer and after the mechanical tests were performed. Additionally, no significant marks resulting from the manufacturing process were observed. CONCLUSION: All mini-implants tested presented adequate surface morphology. The resistance of mini-implants to fracture safely allows placement in 1 and 2-mm cortical thickness. However, in 3-mm cortical thickness and dense bones, pre-drilling with a bur is recommended before insertion.

Insertion torque versus mechanical resistance of mini- implants inserted in different cortical thickness

OBJECTIVE: This study aimed to measure insertion torque, tip mechanical resistance to fracture and transmucosal neck of mini-implants (MI) (Conexão Sistemas de PróteseT), as well as to analyze surface morphology. METHODS: Mechanical tests were carried out to measure the insertion torque of MIs in different cortical thicknesses, and tip mechanical resistance to fracture as well as transmucosal neck of MIs. Surface morphology was assessed by scanning electron microscopy (SEM) before and after the mechanical tests. RESULTS: Values of mechanical resistance to fracture (22.14 N.cm and 54.95 N.cm) were higher and statistically different (P < 0.05) from values of insertion torque for 1-mm (7.60 N.cm) and 2-mm (13.27 N.cm) cortical thicknesses. Insertion torque was statistically similar (P > 0.05) to torsional fracture in the tip of MI (22.14 N.cm) when 3 mm cortical thickness (16.11 N.cm) and dense bone (23.95 N.cm) were used. Torsional fracture of the transmucosal neck (54.95 N.cm) was higher and statistically different (P < 0.05) from insertion torsional strength in all tested situations. SEM analysis showed that the MIs had the same smooth surface when received from the manufacturer and after the mechanical tests were performed. Additionally, no significant marks resulting from the manufacturing process were observed. CONCLUSION: All mini-implants tested presented adequate surface morphology. The resistance of mini-implants to fracture safely allows placement in 1 and 2-mm cortical thickness. However, in 3-mm cortical thickness and dense bones, pre-drilling with a bur is recommended before insertion. .

OBJETIVOS: os objetivos foram determinar os torques de inserção, a resistência mecânica à fratura da ponta e do perfil transmucoso de mini-implantes (MI) de uma marca comercial (Conexão Sistemas de Prótese), e analisar sua morfologia de superfície. MÉTODOS: foram realizados testes mecânicos para medir o torque de inserção dos MI em corticais de diferentes espessuras, também foi avaliada a resistência à fratura da ponta e do perfil transmucoso. Antes e após os ensaios mecânicos, foi avaliada a superfície dos MI no microscópio eletrônico de varredura (MEV). RESULTADOS: os valores de resistência à fratura dos MI (22,14N.cm2 e 54,95N.cm2) foram maiores e estatisticamente diferentes (p < 0,05) dos torques de inserção nas corticais de 1mm (7,60N.cm2) e de 2mm (13,27N.cm2). Entretanto, o valor do torque de inserção na cortical de 3mm (16,11N.cm2) e no osso denso (23,95N.cm2) foi estatisticamente semelhante (p > 0,05) ao torque de fratura da ponta do MI (22,14N.cm2). O torque de fratura do perfil transmucoso (54,95N.cm2) foi maior e estatisticamente diferente (p < 0,05) dos torques de inserção em qualquer uma das situações testadas. A análise em MEV mostrou que os MI, como recebidos e após os testes mecânicos, possuem superfícies lisas e sem marcas significativas oriundas do processo de fabricação. CONCLUSÃO: os MI avaliados apresentaram adequada morfologia da superfície. A resistência do MI foi compatível com a instalação em corticais de 1 e 2mm, porém, em cortical de 3mm e em ossos densos recomenda-se prévia perfuração com broca. .

Influence of surface treatment on shear bond strength of orthodontic brackets.

INTRODUCTION: The shear bond strength of orthodontic brackets bonded to micro-hybrid and micro-particulate resins under different surface treatment methods was assessed. METHODS: Two hundred and eighty test samples were divided into 28 groups (n = 10), where 140 specimens were filled with Durafill micro-particulate resin and 140 with Charisma composite. In 140 samples, a coupling agent (silane) was applied. The surface treatment methods were: Phosphoric and hydrofluoric acid etching, sodium bicarbonate and aluminum oxide blasting, stone and burs. A Universal Instron Machine was used to apply an occlusal shear force directly to the resin composite bracket surface at a speed of 0.5 mm/min. The means were compared using analysis of variance and multivariate regression to assess the interaction between composites and surface treatment methods. RESULTS: Means and standard deviations for the groups were: Sodium bicarbonate jet 11.27 ± 2.78; burs 9.26 ± 3.01; stone 7.95 ± 3.67; aluminum oxide blasting 7.04 ± 3.21; phosphoric acid 5.82 ± 1.90; hydrofluoric acid 4.54 ± 2.87, and without treatment 2.75 ± 1.49. An increase of 1.94 MPa in shear bond strength was seen in Charisma groups. Silane agent application reduced the Charisma shear bond strength by 0.68 Mpa, but increased Durafill means for bicarbonate blasting (0.83), burs (0.98) and stone drilling (0.46). CONCLUSIONS: The sodium bicarbonate blasting, burs and stone drilling methods produced adequate shear bond strength and may be suitable for clinical use. The Charisma micro hybrid resin composite showed higher shear bond means than Durafill micro particle composite.

Influence of surface treatment on shear bond strength of orthodontic brackets

INTRODUCTION: The shear bond strength of orthodontic brackets bonded to micro-hybrid and micro-particulate resins under different surface treatment methods was assessed. METHODS: Two hundred and eighty test samples were divided into 28 groups (n = 10), where 140 specimens were filled with Durafill micro-particulate resin and 140 with Charisma composite. In 140 samples, a coupling agent (silane) was applied. The surface treatment methods were: Phosphoric and hydrofluoric acid etching, sodium bicarbonate and aluminum oxide blasting, stone and burs. A Universal Instron Machine was used to apply an occlusal shear force directly to the resin composite bracket surface at a speed of 0.5 mm/min. The means were compared using analysis of variance and multivariate regression to assess the interaction between composites and surface treatment methods. RESULTS: Means and standard deviations for the groups were: Sodium bicarbonate jet 11.27±2.78; burs 9.26±3.01; stone 7.95±3.67; aluminum oxide blasting 7.04±3.21; phosphoric acid 5.82±1.90; hydrofluoric acid 4.54±2.87, and without treatment 2.75±1.49. An increase of 1.94 MPa in shear bond strength was seen in Charisma groups. Silane agent application reduced the Charisma shear bond strength by 0.68 Mpa, but increased Durafill means for bicarbonate blasting (0.83), burs (0.98) and stone drilling (0.46). CONCLUSION: The sodium bicarbonate blasting, burs and stone drilling methods produced adequate shear bond strength and may be suitable for clinical use. The Charisma micro hybrid resin composite showed higher shear bond means than Durafill micro particle composite.

INTRODUÇÃO: foram avaliadas as forças de cisalhamento após colagem de braquetes ortodônticos em superfícies resinosas microparticuladas ou micro-híbridas, após diferentes tratamentos de superfície. MÉTODOS: foram utilizados 280 corpos de prova, divididos em grupos de 10 elementos cada, sendo 140 preenchidos com resina microparticulada Durafill e 140 com resina micro-híbrida Charisma. Os tratamentos de superfície envolveram: ácido fosfórico, ácido fluorídrico, jato de bicarbonato de sódio, jato de óxido de alumínio, pedra e broca. A silanagem foi utilizada em metade dos grupos. O cisalhamento foi realizado com a máquina universal de testes EMIC DL 10000 MF, com célula de 10kg e velocidade de 0,5mm/min. As comparações entre as forças de cisalhamento foram obtidas por meio da análise de variância, e o grau de interação entre os tipos de compósito e o preparo de superfície foram obtidos por meio de uma regressão multivariada. RESULTADOS: as médias e desvios-padrão foram: jato de bicarbonato = 11,27 ± 2,78; broca = 9,26 ± 3,01; pedra = 7,95 ± 3,67; jato de óxido de alumínio = 7,04 ± 3,21; ácido fosfórico = 5,82 ± 1,90; ácido fluorídrico = 4,54 ± 2,87; e sem preparo = 2,75 ± 1,49. Um acréscimo de 1,94MPa foi obtido com o uso do compósito Charisma. A silanagem reduziu em 0,68MPa as médias do compósito Charisma, e aumentou o Durafill com uso do jato de bicarbonato (0,83), broca (0,98) e pedra (0,46). CONCLUSÃO: os preparos com jato de bicarbonato, broca e pedra obtiveram médias de forças apropriadas para colagem. O compósito Charisma apresentou forças de maior intensidade que as da resina Durafill.

Orthodontic implants: concepts for the orthodontic practitioner.

Orthodontic implants have become a reliable method in orthodontic practice for providing temporary additional anchorage. These devices are useful to control skeletal anchorage in less compliant patients or in cases where absolute anchorage is necessary. There are a great number of advantages in this new approach which include easy insertion, decreased patient discomfort, low price, immediate loading, reduced diameter, versatility in the forces to be used, ease of cleaning, and ease of removal. However, a proper management of the screws by the practitioner is necessary in order to increase the success rate of the technique. The purpose of this paper is to update practitioners on the current concepts of orthodontic implants and orthodontic mechanics.

Propriedades em flexão de fios de liga de Ni-Ti / Bending properties of Ni-Ti alloys wires

As ligas de niquel-titânio (Ni-Ti) são usadas na fabricação de fios ortodônticos devido principalmente a sua maior resiliência e menor módulo de elasticidade quando comparadas com outras ligas metálicas, especialmente o aço inoxidável. O objetivo do presente trabalho foi comparar as propriedades mecânicas em flexão de fios de liga com memória de forma de diferentes fabricantes e lotes. Dois lotes de três fabricantes foram ensaiados em flexão três pontos de acordo com a norma ISO 15841:2006(E). Os resultados mostraram que os fios designados como termoativados geram tensões menores que os fios designados como superelásticos, observou-se variações de até 28% entre fios designados como superelásticos e 31% entre fios designados como termoativados. Na comparação dos lotes do mesmo fabricante observou-se também a não homogeneidade entre os fios.

The nickel-titanium (Ni-Ti) alloys are used in the manufacture of orthodontic wires mainly due to its greater resilience and low modulus of elasticity when compared to other alloys, particularly stainless steel. The aim of this study was to compare the mechanical properties of shape memory alloys wires in three-point bending in different manufacturers. Two lots of three manufacturers were tested in three-point bending according to ISO 15841:2006 (E). The results showed that wires designated as termoactivated generated lower tensions than the designated as superelastic, variations of up to 28% between wires designated as superelastic and 31% between wires d esignated as termoactivated were found. In the manufacturer lots comparison was also not observed homogeneity between wires.

Propriedades mecânicas de fios ortodônticos de níquel-titânio superelásticos e termoativados de diferentes lotes comerciais / Mechanical properties of superelastic and heat-activated nickel-titanium orthodontic archwires from different commercially available lots

Objetivou-se determinar e comparar as propriedades mecânicas de fios ortodônticos de NiTi 0,014" superelásticos (SE) e termoativados (TA) de diferentes fabricantes e lotes comerciais. A amostra foi composta por 132 exemplares divididos em 22 grupos (n=6) de acordo com a marca comercial, lote e propriedades SE ou TA. Ensaios de flexão em três pontos foram realizados na máquina de ensaios Emic DL 10000 com uma célula de carga de 5N, flecha de 3,1 mm a 36±1oC, conforme normatização ISO 15841. Obtiveram-se curvas tensão vs deslocamento e foi determinada a diferença entre as propriedades mecânicas através da análise de variância associada ao teste de Tukey (P≤0,05). Fios TA apresentaram menores tensões médias no carregamento (TMC) descarregamento (TMD), à resiliência total (RT) e potencial (RP), enquanto demonstraram maiores valores de resiliência de histerese (RH) e histerese mecânica (HM) que os exemplares SE. Considerando-se todas as propriedades mecânicas analisadas, não foram observadas diferenças entre os grupos Morelli e Orthometric SE e TA; 3M e Tp SE; GAC e Tp, e, Orthometric e Orthosource TA. Os fios Orthosource SE e TA revelaram semelhanças às propridades analisadas. (P>0,05). Entre os diferentes lotes comerciais de mesmos fabricantes e tipos de fios, os grupos 3M SE, Tp SE, Tp TA e Orthosource TA demonstraram diferença às propriedades TMC, TMD, RT e RP (P>0,05).

The objective of this work was to evaluate and compare the mechanical properties of different commercial lots of superelastic (SE) and heat activated (HA) .014-inch NiTi orthodontic wires. The sample examined was composed of 132 NiTi wires divided in 22 groups (n=6) according to commercial brands, lots and SE or HA properties. Three-point bending tests were conducted in accordance to ISO 15841 norm. An Emic DL 10000 testing machine with a 5N load cell applied deflections until 3.1 mm at 36±1oC. Stress-deflection diagrams were determined and different mechanical properties were compared by analysis of variance and Tukey test (P≤.05). HA wires showed lower load (LMS) and unload (UMS) mean stress, total (TR) and potential (PR) resilience while higher hysteresis resilience (HR) and mechanical hysteresis (MH) than SE ones (P<.05). Among all mechanical properties, no differences were seen between Morelli and Orthometric SE and HA groups; 3M and Tp SE groups; GAC and Tp and Orthometric and Orthosource TH groups. Orthosource revealed the same mechanical properties in SE and HA archwires (P>.05). According to comparisons between different lots from the same manufacturer and wire types, 3M SE, Tp SE, Tp HA, and Orthosource HA groups matched in LMS, UMS, TR and PR (P>.05).

Do sucking habits in preschool children influence the position of the primary incisors?

The aim of this study was to verify whether sucking habits influence the position of the primary incisors. The sample comprised 34 preschool children (mean age 44 months ± 9 months). They were divided into three groups: group B (n=9) with a baby bottle habit; group BP (n=13) with baby bottle and pacifier habits; and a control group C (n=12) with no sucking habit. Data were derived from face-to-face interviews with the parents/guardians, oral examinations, study casts, facial photographs (frontal/lateral views), and cephalograms. The cephalograms were scanned and subsequently analyzed by one trained and calibrated operator. The cephalometric parameters recorded were: interincisal angle (U1/L1), U1/NA (angle/distance), and L1/NB (angle/distance). The data were analyzed using Stata 7.0. The Kruskall-Wallis test was used to compare the cephalometric measurements in the children with and without sucking habits. The level of significance was set at P≤.05. This study found a significant relationship between existing sucking habits and a protrusion of the maxillary and mandibular primary incisors.

A influência dos hábitos de sucção de chupeta e uso de mamadeira na dentição decídua / Influence of pacifier and baby bottle in primary dentition

Verifica-se a deficiência de informações sobre o momento do início das alterações faciais e dentárias presentes na criança portadora de hábitos de sucção. Portanto, objetivou-se descrever as características oclusais da dentição decídua em pré-escolares de diferentes faixas etárias e avaliar a frequência e gravidade da mordida aberta anterior; a inclinação dos incisivos decíduos em relação as suas bases ósseas; o ângulo interincisal; o trespasse horizontal; a prevalência de mordida cruzada posterior; e a relação entre os caninos e o tipo de plano terminal. A amostra foi composta por 34 pacientes distribuídos em: grupo M (nove pacientes): com o hábito de mamadeira; grupo MC (13 pacientes): com o hábito de mamadeira e chupeta; grupo C (12 pacientes): controle (sem hábitos). A coleta de dados foi realizada através de entrevistas face a face, exame clinico, modelos de estudo, fotografias intra e extrabucais e radiografias cefalométricas laterais. Observou-se uma maior frequência de mordida aberta anterior nos grupos "mamadeira" e "mamadeira e chupeta". Verificou-se uma diferença estatisticamente significativa entre os grupos quando se avaliou a presença de mordida aberta e a prática de hábitos (p=O,02). A chance de apresentar mordida aberta anterior era 9,2 vezes maior entre as crianças que praticavam algum hábito de sucção (p=O,05). As medidas lineares dos incisivos superiores e inferiores em relação às suas bases ósseas mostraram um aumento estatisticamente significativo em relação à prática de hábitos de sucção. Concluiu-se que o hábito de sucção apresenta efeitos deletérios nas características de normalidade da dentição decídua em idade pré-escolar.

This study aims to describe preschool oclusal characteristics of the deciduous dentition in different phases and evaluating alterations ofthe normal occlusion, while associates the pacifier sucking habits and the use of baby's bottle. The study purposed association related to the existence of each type of habit with: frequency and gravity of the open bite; inclination of the deciduous incisors in the bone baseline; interincisal angle; overjet; prevalence of posterior crossbite; relation between canines and molars. The population was defined as children who presented complete deciduous dentition, of both gender, wuh ages between 2 and 5 years. Sample was composed of 34 patients distributed in: Group M (9) - baby's bottle habit, without use of pacifier; GroupMe (13) - habits of baby 's bottle and pacifier; Group C (12) - control (without sucking of pacifier or baby's bottle). The data 's collection was carried through interviews, clinical examination, study models, photographs and cephalometric x-rays. The results showed a high frequency of anterior open bite in patients of habits groups. Patients between 21 and 36 months presented a higher prevalence of anterior open bite when compared witn others (p=O.02). Through the logistic regression it was verified that the possibility to present open bite was 9.2 times higher between children who practiced some sucking habits (p=O.05). Moreover,linear measures of upper and lower incisors in the baseline bone had shown significant increase in patients wuh sucking habits. This study concluded that sucking habits practice have deleterious effects in primary dentition of preschool children.

Avaliação da degradação de elásticos ortodônticos intraorais de látex / Force extension relaxation of medium force orthodontic latex elastics

Avaliou-se a taxa de degradação de elásticos ortodônticos de látex de diferentes fabricantes e diâmetros em diversos intervalos de tempo. Grupos de 15 elásticos de força média dos fabricantes AmericanOrthodontics (Sheboygan, Wis, EUA), Tp (La Porte, IN, EUA), Morelli (Sorocaba, SP, Brasil) e Uniden (Sorocaba, SP, Brasil); de diâmetros 3/16, 1/4 e 5/16 foram analisados nos intervalos de 0,1,3,6,12 e 24 horas, totalizando-se 1080 espécimes. Os elásticos foram estirados individualmente à distância de 30mm, respeitando-se o intervalo de um minuto entre cada estiramento. Os materiais foram acondicionados imersos em água deionizada à 37°C. Realizou-se leitura das forças na máquina de ensaios Emic DL 500 (Emic Co, Sao Paulo, Brasil) à velocidade de 30 mm/min, com uma célula de 2Kg (Emic Co, Sao Paulo, Brasil). A leitura de cada elástico consumiu aproximadamente um minuto. Teste Kruskal-wallis com correções por Dunns aferiu significância estatística dos resultados. Foram observadas diferenças entre os grupos analisados, exceto às marcas Morelli e Tp. Foram significativas as inferências das variáveis tempo e marca comercial. Em 0 hora, a relação entre as forças geradas foi Morelli>AO>Uniden>Tp para elásticos 3/16 (p=0,0016) e 1/4 (p=0,0016) e, de Morelli>AO>Tp>Uniden para elásticos 5/16 (p=0,0087). Após 24 horas, as porcentagens de degradação dos elásticos foram AO>Morelli>Uniden>Tp no diâmetro 3/16; AO>Tp>Morelli>Uniden no diâmetro 1/4 e Tp>AO>Uniden>Morelli para elásticos de diâmetro 5/16. O comportamento no intervalo de 0-24 horas demonstrou uma queda acentuada no período de 0-3 horas, um ligeiro aumento em 3-6 horas, seguido de uma queda progressiva no intervalo de 6-24 horas.

The purpose of this study was to evaluate the force relaxation of different brands and diameters of latex elastics occurring during different times. Groups of 15 medium forces elastics from manufacturers: American Orthodontics (Sheboygan, Wis, USA), Tp (La Porte, IN, USA), Morelli Orthodontics (Sorocaba, SP, Brazil) and Uniden Orthodontics (Sorocaba, SP, Brazil) with diameters: 3/16, 1/4 and 5/16 inch size were tested at 0,1,3,6,12,24 hours, making a total of 1080 specimens. An apparatus was designed to simulate oral environments during elastics stretching. The forces were read after 1,3,6,12 and 24-hour periods in Emic testing machine (Emic Co, Sao Paulo, Brazil) with 30 mm/min cross-head speed and load cell of 2Kg Emic force (Emic Co, Sao Paulo, Brazil). Kruskal-Wallis and Dunns tests were used to identify statistical significance. Overall, there were statistically differences among the different manufacturers at all observation intervals, except between Morelli and Tp. Significantly variability were seen in Morelli and Uniden force delivery. The relationships among loads at 0-hour time period were as follows: Morelli>AO>Uniden>Tp for 3/16 (p=.0016) and 1/4 elastics (p=.0016) and Morelli>AO>Tp>Uniden for 5/16 elastics (p=.0087). The forces relaxation over the 24-hour time period were AO>Morelli>Uniden>Tp for 3/16 elastics; AO>Tp>Morelli>Uniden for 1/4; and Tp>AO>Uniden>Morelli for 5/16 elastics.The force decay pattern show a notable drop-off of forces during 0-3 hours, a slight increase in force values from 3-6 hours and a progressive force decay was seen over 6-24 hours.