Elastic Chain Research Articles

Evaluation of the mechanical behaviour of different devices for canine retraction

OBJECTIVE: To mechanically evaluate different systems used for canine retraction. METHODS: Three different methods for partial canine retraction were evaluated: retraction with elastic chain directly attached to bracket; elastic chain connected to bracket hook and with sliding jig activated with the aid of an elastic chain attached to a mini-implant. For this evaluation, a Typodont was adapted to simulate the desired movements when exposed to a heat source. After obtaining the measurements of the movements, statistical analysis was performed. RESULTS: The mini-implant/sliding jig system (Groups M 0.018-in and M 0.019 x 0.026-in) favored less extrusion and distal inclination of the canines in the retraction stage (p < 0.005). Meanwhile, the retraction system with elastic chain directly attached to the orthodontic brackets (Groups C 0.018-in and 0.019 x 0.026-in) favored greater inclination and extrusion than the others, followed by the system of elastic chain attached to the hook (Groups G 0.018-in and 0.019 x 0.026-in). CONCLUSIONS: Canine retraction with the mini-implant/sliding jig system showed the best mechanical control. The worst results were observed with a 0.018 archwire when the elastic chain was attached to the bracket.

Esthetic orthodontic treatment with a double J retractor and temporary anchorage devices

This clinical article reports an esthetic treatment option for managing a Class II malocclusion in an adult. The patient, a woman aged 24 years 2 months, had crowding and a convex profile. She was treated with maxillary first premolar extractions, a double J retractor, and temporary skeletal anchorage devices in the maxillary arch. Posttreatment records after 2 years showed excellent results with good occlusion and long-term stability.

Dynamic mechanical properties of curaua composites

AbstractIn this study, we aimed to evaluate the characteristics of curaua composites using dynamic mechanical analysis. Curaua composites with distinct fiber volume fractions (11–38%) were studied, and their storage and loss moduli were found to increase with reinforcement content. On the other hand, the activation energy of the relaxation process in the glass‐transition region decreased with the curaua content; this conclusion was corroborated by the elastic chain concentration results. The Cole–Cole plots became flattened as the curaua content increased; this was indicative of a more homogeneous system, and the tan δ peak height and peak width at half‐height decreased. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Correction of Mesially Impacted Lower Second Molar

Impaction of the lower second molar is not a common problem, but it is very challenging for both orthodontist and oral surgeon. We report the case of patient who complained of a delay in eruption of both the upper and lower second molars. A panoramic radiograph revealed the presence of all permanent teeth and a severe mesial inclination of the left lower second molars and developing third molars. A removable appliance with an uprighting spring was fixed mouth. After two months, a miniscrew was applied maxillar posterior buccal area. And then, an elastic chain was put between miniscrew and lower second molar. Within a period of 4 months the tooth was completely upright. After 5 months, a panoramic radiograph revealed complete uprighting of the tooth, with bone regeneration. Orthodontic uprighting techniques using miniscrews are more advantageous and offer better long term prognosis than surgical uprighting. The timing of treatment and the biomechanics involved determine the success. doi:10.4021/ jmc272w

The Strength and Conditioning Practices of Strongman Competitors

This study describes the results of a survey of the strength and conditioning practices of strongman competitors. A 65-item online survey was completed by 167 strongman competitors. The subject group included 83 local, 65 national, and 19 international strongman competitors. The survey comprised 3 main areas of enquiry: (a) exercise selection, (b) training protocols and organization, and (c) strongman event training. The back squat and conventional deadlift were reported as the most commonly used squat and deadlift (65.8 and 88.0%, respectively). Eighty percent of the subjects incorporated some form of periodization in their training. Seventy-four percent of subjects included hypertrophy training, 97% included maximal strength training, and 90% included power training in their training organization. The majority performed speed repetitions with submaximal loads in the squat and deadlift (59.9 and 61.1%, respectively). Fifty-four percent of subjects incorporated lower body plyometrics into their training, and 88% of the strongman competitors reported performing Olympic lifts as part of their strongman training. Seventy-eight percent of subjects reported that the clean was the most performed Olympic lift used in their training. Results revealed that 56 and 38% of the strongman competitors used elastic bands and chains in their training, respectively. The findings demonstrate that strongman competitors incorporate a variety of strength and conditioning practices that are focused on increasing muscular size, and the development of maximal strength and power into their conditioning preparation. The farmers walk, log press, and stones were the most commonly performed strongman exercises used in a general strongman training session by these athletes. These data provide information on the training practices required to compete in the sport of strongman.

Anterior Open Bite Closure: A Case Report

Anterior open bite is often caused by a downward rotation of the mandible and/or by excessive eruption of the posterior teeth. In such cases, it is difficult to establish absolute anchorage for molar intrusion by traditional orthodontic mechanics. This article reports the successful treatment of a severe skeletal anterior open bite case using titanium screw anchorage. A female patient of 31 years of age had open bite of 7 mm with increased facial height. The mini screws were implanted on both maxilla and the mandible, and an intrusion force was provided with elastic chains for 13 months. After active treatment of 19 months, her upper and lower first molars were intruded by about 3 mm each, and good occlusion was achieved. Her retrognathic chin and convex profiles were improved by an upward rotation of the mandible. Our result suggests that titanium screws are useful for intrusion of molars in anterior open bite cases.

The Force Degradation of Elastic Chain in Different Environments and for Different Intervals (An In Vitro Study)

The Force Degradation of Elastic Chain in Different Environments and for Different Intervals (An In Vitro Study)

Viscoelastic Behavior of the Polymerized Ionic Liquid Poly(1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonylimide))

Dynamic melt viscoelastic behavior for polymerized ionic liquids, poly(1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonylimide)) (PC2VITFSI), with various molecular weights was investigated in the frequency/temperature range from the glass to the terminal region. Viscoelastic spectra at given temperatures for PC2VITFSI with lower molecular weight were able to be well superimposed on each other to make a master curve. PC2VITFSI with a molecular weight larger than 1.4 × 105 were entangled with each other, showing a rubbery region in the master curves. However, viscoelastic spectra for PC2VITFSI with higher molecular weight (larger than 2.2 × 105) were not superimposed in the rubbery and terminal regions due to the presence of two rubbery elastic origins, i.e., chain entanglement and ionic aggregates. The presence of huge ionic aggregates was unable to be confirmed by SAXS measurements, but the formation of ion pairs between a cation and an anion was supported by the WAXS profiles. Master curves of PC2VITFSI exhibited extended shoulders in the glass–rubber transition region; these arose from the relaxation mode due to segmental motions of positively charged polymer chains affected by neighboring TFSI– anions. The entanglement and critical molar mass of PC2VITFSI were determined to be 4.5 × 104 and 2.2 × 104, respectively.

Evaluation of space closure rate during canine retraction with nickel titanium closed coil spring and elastomeric chain.

Aims: . To investigate the rates of space closure achieved by elastomeric chain and nickel titanium coil springs with the evaluation of the effects of using different bracket types on the rate of space closure during its retraction along different sizes of orthodontic arch wires using typodont simulation system (Ormco). Materials and Methods: The standardization criteria were all typodont teeth situated in well aligned position, covered and immobilized by the acrylic bite except canine, elastic chain and nickel – titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge. The available space was 13.5mm (the rate of space closure). Results: The present study showed that when using elastic chain as a method of canine retraction gave rise to a a significant decrease in the rate of space closure as compared with nickel – titanium closed coil spring also sliding the canine using ceramic brackets gave rise significant reduction in the rate of space closure than when using stainless steel brackets. Another finding of the present study showed that sliding the canine on large rectangular arch wire (0.019x0.025 inch) gave rise to a significant reduction in the rate of space closure when com-pared with 0.018 inch and 0.018x0.022 inch arch wires were used. Conclusions: It was concluded that the canine retraction with 0.018 inch wire on Roth stainless steel bracket by closed coil spring gave rise a large amount of space closure rate. While the opposite is true for canine retraction with 0.019x0.025 inch wire on standard ceramic bracket by elastic chain retraction method.

Influence of the Degree of Activation on the Plastic Deformation of Orthodontic Elastic Chains

Objetivo: Avaliar a influencia do grau de ativacao na deformacao plastica de elasticos ortodonticos em cadeia em funcao do tempo que permaneceram estirados. Metodo: Foram testadas 72 amostras de cadeia elastica da marca Morelli, tamanho medio cristal, que foram mantidas em um jig confeccionado, especialmente, para este fim, com diferentes graus de ativacao, 30%, 50% e 70% dos seus comprimentos iniciais, sendo avaliadas 24 cadeias elasticas para cada grau de ativacao. Os elasticos foram mantidos em suas embalagens plasticas originais, como recomendado pelo fabricante, ate serem testados. O jig com os elasticos foram conservados em um recipiente plastico contendo saliva artificial e mantidos em uma estufa artesanal com temperatura controlada de 37oC ± 1oC por todo o tempo do experimento, sendo removidos deste ambiente somente ao final de 3 semanas de ativacao. As medidas dos comprimentos iniciais e finais de seis elos de cada cadeia elastica foram realizadas utilizando-se um paquimetro digital de precisao e o percentual de deformacao plastica foi calculado em relacao ao comprimento inicial. A comparacao entre os valores medios de deformacao plastica sofrida pelos elasticos nos diferentes graus de ativacao foi realizada estatisticamente com o auxilio do programa SPSS (Statistical Package for Social Sciences), versao 15.0. Resultados: Os valores medios encontrados, 13,89%, 20,66% e 30,68% de deformacao plastica, para os diferentes graus de ativacao, respectivamente, foram submetidos a teste estatistico analise de variância (ANOVA) com nivel de significância de 5%, tendo sido encontrada significância estatistica entre os mesmos. Conclusao: O grau de ativacao influenciou de forma significativa a deformacao plastica sofrida pelos elasticos testados.

Hybridization effect on the mechanical and dynamic mechanical properties of curaua composites

a b s t r a c t This study aims to evaluate the performance of curaua/glass hybrid composites focusing on mechanical and dynamic mechanical analysis (DMA). Composites with distinct glass/curaua fiber loading ratios were studied. Flexural strength and modulus, impact strength and Barcol hardness increased for higher glass fiber content. The same was found for storage and loss modulus. The activation energy of the relaxation process in the glass transition region showed a maximum for the all-glass composite, corroborating with the results of concentration of elastic chains (� e). Cole-Cole plots were obtained and found to follow the same trend regardless of the glass content, whereas peak height and peak width at half-height were maximum for the all-glass composite.

A comparative evaluation of rate of space closure after extraction using E-chain and stretched modules in bimaxillary dentoalveolar protrusion cases

Aim of this study was to compare the rate of space closure between E-chain mechanics in one side of upper arch and by elastomeric module with ligature wire on the contralateral side in same patient. Thirty bimaxillary dentoalveolar protrusion cases were taken up for comprehensive fixed orthodontic treatment after extraction of all first premolars to retract both upper and lower anterior teeth. After initial alignment and levelling, alginate impressions were made for upper and lower arches and models constructed. In the upper arch model a vernier caliper was used to measure the extraction space in both sides from middle point of distal surface of canine to the middle most point of mesial surface of second premolar. This is the amount of space present before the onset of retraction mechanics. During space closure procedure two different retracting components were applied in right and left sides of each case. On right side elastic chain (E-chain) applied in both upper and lower arches and on left side elastomeric module with steel ligature (0.010") stretched double its diameter fixed in both arches. Both the mechanisms produced approximately 250-300 g of force as measured by a tension gauge. After onset of retraction mechanism all patients were recalled after every six weeks for three visits. In all these three visits modules and E-chains were changed. In all three visits impression was made, models constructed, and the remaining available space was measured by a vernier caliper up to 0.1 mm level variations. Mean value for total space closure in case of E-chain was 2.777 mm whereas in case of module with ligature wire the value increased to 3.017 mm. Mean value for rate of space closure in case of E-chain was 0.2143 mm, whereas in case of module with ligature wire the value increased to 0.2343 mm with a standard deviation of 0.001104 and 0.001194, respectively. The standard deviation for total space closure was 0.1305 for E-chain and 0.1487 for module with ligature wire. Space closure by elastomeric module with ligature wire is better than the E-chain.

Calculation of the Helmholtz potential of an elastic strand in an external electric field

We derive from statistical mechanics the Gibbs free energy of an elastic random-walk chain affected by the presence of an external electric field. Intrachain charge interactions are ignored. In addition, we find two approximations of the Helmholtz potential for this system analogous to the gaussian and Cohen-Padé approximations for an elastic strand without the presence of an electric field. Our expressions agree well with exact numerical calculations of the potential in a wide range of conditions. Our analog of the gaussian approximation exhibits distortion of the monomer density due to the presence of the electric field, and our analog of the Cohen-Padé approximation additionally includes finite chain extensibility effects. The Helmholtz potential may be used in modeling the dynamics of electrophoresis experiments.

Comparison of the force systems of 3 appliances on palatally impacted canines

Although much imaging research has focused on the localization and the management of impacted canines, optimal biomechanics for successful recovery are not clear. The purpose of this research was to compare the 3 mechanics--Kilroy spring, elastic chain, and steel ligature wire--used for the management of impacted canines by quantifying the 6 components of force systems involved with each system. A dentoform model was modified to simulate a palatally impacted canine. Load cells installed in the dentoform simultaneously measured the 3 forces (Fx, Fy, Fz) and the 3 moments (Tx, Ty, Tz) on the canine. The activation range and force system attenuation as the canine moved were also measured. The results were analyzed statistically. The Kilroy spring has an activation range of 13 mm (Fz), the elastic chain has an activation range of 12 mm (Fz), and the ligature wire has an activation range of 1 mm (Fz). The full range of the elastic chain cannot be used because of its limited elastic behavior. The 3-dimensional force system for canine recovery mechanics can be quantified by using these devices. Quantification of the force system provides critical information for appropriate selection of an optimal appliance.

Orthodontic space closure after first molar extraction without skeletal anchorage

The aim of the study was an analysis of effects and side-effects during mesialization of second molars after extraction of the first permanent molars using the anterior dentition/premolars (PM) as an anchorage unit. A total of 35 patients were examined retrospectively who had undergone unilateral or bilateral first permanent molar extraction in the upper or lower arch due to carious lesions. Space closure was carried out in all cases through mesialization of the second molar using an elastic chain fixed to an edgewise stainless steel archwire and tying the anterior dentition/PM together with a continuous laceback ligature. Tooth movement was assessed from lateral cephalograms, orthopantomograms (OPGs) and images of the patient's study casts taken before and after the end of therapy. Space closure after first molar extractions by mesialization of the second molars without skeletal anchorage was largely achieved by bodily forward movement of the teeth, including a small tipping component or tooth-uprighting component when molars were already mesially inclined. Unilateral and bilateral mesialization of the second molars led to retrusion in the maxilla and mandible [(∆incl.=-3.6° (max., bil.), ∆incl.=-4.2° (mand., bil.)] and to translational retraction [(∆s=-2.3 mm (max., bil.), ∆s=-1.6 mm (mand., bil.)] of the incisors. Examination of the soft tissues revealed an increased posterior displacement of the upper and lower lips to the esthetic line [(∆s=-2.8 mm (max. bil.), ∆s=-2.2 mm (mand., bil.)]. In cases of unilateral mesialization less than 50% of the patients had a slight midline deviation in the mandible towards the extraction side. Side effects during mesialization of the second molars without skeletal anchorage in the anterior dentition/PM were observed primarily affecting the incisors integrated into the anterior anchorage unit. These side-effects resulted in posterior displacement of the soft tissues, including a change in profile. This must be taken into consideration when taking this therapeutic approach.

Porous calcium alginate–gelatin interpenetrated matrix and its biomineralization potential

Artificial bone composites exhibit distinctive features by comparison to natural tissues, due to a lack of self-organization and intimate interaction apatite-matrix. This explains the need of "bio-inspired materials", in which hydroxyapatite grows in contact with self-assembling natural polymers. The present work investigates the function of a rational design in the hydroxyapatite-forming potential of a common biopolymer. Gelatin modified through intrinsic interactions with calcium alginate led through freeze-drying to porous hydrogels, whose architecture, constitutive features and chemistry were investigated with respect to their role on biomineralization. The apatite-forming ability was enhanced by the porosity of the materials, while the presence of alginate-reinforced Gel elastic chains, definitely favored this phenomenon. Depending on the concentration, polysaccharide chains act as "ionic pumps" enhancing the biomineralization. The mineralization-promoting effect of the peptide-polysaccharide network strictly depends on the hydrogels structural, compositional and morphological features derived from the interaction between the above mentioned two components.

Correction of Mesially Impacted Lower Second Molar

Impaction of the lower second molar is not a common problem, but it is very challenging for both orthodontist and oral surgeon. We report the case of patient who complained of a delay in eruption of both the upper and lower second molars. A panoramic radiograph revealed the presence of all permanent teeth and a severe mesial inclination of the left lower second molars and developing third molars. A removable appliance with an uprighting spring was fixed mouth. After two months, a miniscrew was applied maxillar posterior buccal area. And then, an elastic chain was put between miniscrew and lower second molar. Within a period of 4 months the tooth was completely upright. After 5 months, a panoramic radiograph revealed complete uprighting of the tooth, with bone regeneration. Orthodontic uprighting techniques using miniscrews are more advantageous and offer better long term prognosis than surgical uprighting. The timing of treatment and the biomechanics involved determine the success. J Med Cases. 2011;2(6):236-239 doi: https://doi.org/10.4021/jmc272w

Efficient usage of implant anchorage to treat overerupted maxillary first molar and mesially inclined mandibular molars

This case report demonstrates the efficient use of implant anchorage in a patient with mesially inclined mandibular molars and an overerupted maxillary molar. A 14-year-old girl had an overerupted maxillary right first molar, possibly because of severely inclined mandibular right molars. Two-step use of miniplate anchorage in the right zygomatic process was proposed. As the first step, the overerupted maxillary first molar was intruded with elastic chains from the miniplate for 10 months. Then the maxillary right molars were distalized by using the miniplate to correct the Class II molar relationship. In the mandible, the first molar was extruded with intermaxillary elastics applied from the miniplate to the molar for 7 months after the uprighting of the mandibular right second molar. The results suggest that the use of 2-step implant anchorage is efficient for intrusion and distalization of maxillary molars and extrusion and uprighting of mandibular inclined molars.

Looping probabilities of elastic chains: A path integral approach

We consider an elastic chain at thermodynamic equilibrium with a heat bath, and derive an approximation to the probability density function, or pdf, governing the relative location and orientation of the two ends of the chain. Our motivation is to exploit continuum mechanics models for the computation of DNA looping probabilities, but here we focus on explaining the novel analytical aspects in the derivation of our approximation formula. Accordingly, and for simplicity, the current presentation is limited to the illustrative case of planar configurations. A path integral formalism is adopted, and, in the standard way, the first approximation to the looping pdf is obtained from a minimal energy configuration satisfying prescribed end conditions. Then we compute an additional factor in the pdf which encompasses the contributions of quadratic fluctuations about the minimum energy configuration along with a simultaneous evaluation of the partition function. The original aspects of our analysis are twofold. First, the quadratic Lagrangian describing the fluctuations has cross-terms that are linear in first derivatives. This, seemingly small, deviation from the structure of standard path integral examples complicates the necessary analysis significantly. Nevertheless, after a nonlinear change of variable of Riccati type, we show that the correction factor to the pdf can still be evaluated in terms of the solution to an initial value problem for the linear system of Jacobi ordinary differential equations associated with the second variation. The second novel aspect of our analysis is that we show that the Hamiltonian form of these linear Jacobi equations still provides the appropriate correction term in the inextensible, unshearable limit that is commonly adopted in polymer physics models of, e.g. DNA. Prior analyses of the inextensible case have had to introduce nonlinear and nonlocal integral constraints to express conditions on the relative displacement of the end points. Our approximation formula for the looping pdf is of quite general applicability as, in contrast to most prior approaches, no assumption is made of either uniformity of the elastic chain, nor of a straight intrinsic shape. If the chain is uniform the Jacobi system evaluated at certain minimum energy configurations has constant coefficients. In such cases our approximate pdf can be evaluated in an entirely explicit, closed form. We illustrate our analysis with a planar example of this type and compute an approximate probability of cyclization, i.e., of forming a closed loop, from a uniform elastic chain whose intrinsic shape is an open circular arc.

Molar uprighting with mini screws: comparison among different systems and relative biomechanical analysis

Starting from a segmented approach, the Authors propose 3 different methods of using mini screws during the process of molar uprighting. The first UPG is performed by placing a mini screw in the retromolar area and by applying an elastic chain loaded between the screw and the molar.The second UPG is made by placing a screw in the retro molar area and by using a small cantilever which is active during intrusion and uprighting.The third UPG is made by using a miniscrew placed a few millimeters mesial to the molar to control the vertical force produced by the uprighting with a long cantilever to the frontal teeth.To assist in the understanding of the different clinical indications, the biomechanical differences between these three systems are analyzed.