Elastic Chain Research Articles

Mathematical Models Drives of Stands of Bridges of Tube-Reducing Machines

We consider computation and selection problems in reduced models for the study of the dynamical load of the stand of the bridge of a tube-reducing machine. We design and analyze the computational scheme and obtain a system of differential equations for investigation of the dynamic processes in the drive. We provide the order of the computation of the dynamic loading, present relations for the computation and reduction of momentum of inertia, rigidity, and momentum included in the computing of elastic chains, and justify the choice of the computational dynamic model. We represent a system of differential equations for computing the loading dynamics for the drive of the stand of the bridge of the tube-reducing machine.

Distalization rate of maxillary canines in an alveolus filled with leukocyte-platelet–rich fibrin in adults: A randomized controlled clinical split-mouth trial

The objective of this study was to evaluate the distalization rate and changes in inclination of the maxillary canines in alveoli preserved with leukocyte-platelet-rich fibrin (L-PRF) membranes in adult patients. The null hypothesis was that there are no differences in the canine distalization movement rate between the treated and the control sides. A total of 21 healthy adult patients with a minimum age of 20years (mean age, 33±5.9years) and Angle Class I or Class II Division 1 malocclusion, who had an indication of extraction of the maxillary first premolars and orthodontic distalization of the maxillary canines were included in this study. A randomized controlled clinical split-mouth trial was conducted; the experimental maxillary side was treated with L-PRF membranes, and the other side served as the control. A randomization sequence of the experimental sides among patients was generated using the random number generation function of Microsoft Excel. Neither the patients nor the operators were blinded. Fifteen days after the extractions, distalization was initiated using an elastic chain applying 150g of force to the canines on a 0.020-in stainless steel archwire. The distalization rate was the main outcome of the study, and it was assessed monthly for 5months through the intraoral use of a flexible ruler. The degree of inclination of the canines was the secondary outcome, and it was evaluated through cone-beam computed tomography. A Shapiro-Wilk test was performed, and a Wilcoxon signed rank test was subsequently used to compare the experimental and the control group. Spearman rank correlation coefficient was calculated to evaluate the correlation between distalization and inclination for each side. Four of the subjects dropped out of the study, leaving a total of 17 patients (n=17). The distalization rate and inclination of the canines were greater on the control side than on the side treated with L-PRF (P<0.05). A weak correlation was found between the distalization rate and inclination of the canines for both sides (control side, ρ=0.17; experimental, ρ=0.11). No harm was observed during the study. The null hypothesis was rejected. The use of L-PRF in young adult patients decreased the rate of distalization and changes in inclination of the maxillary canines compared with the control group. This trial was not registered. The protocol was not published before trial commencement.

Experimental evaluation of strength degradation of orthodontic chain elastics exposed to cigarette combustion smoke

Introduction: Effects of cigars in the performance of dental restorative materials have been largely investigated; however, no information about the role of smoking cigars in strength degradation of orthodontic elastics has been revealed. Aim of the study: evaluate the effect of smoke derived from cigarette combustion on the strength degradation of orthodontic chain elastics. Materials and methods: Four distinct elastics from two different manufacturers were evaluated: Maximum Power Chain Pearl (OTP) (OrthoTechnology); Maximum Power Chain Pearl Tone Blue (OTPB) (OrthoTechnology); Orthodontic Elastic Chain Gray (MG) (Morelli); Orthodontic Elastic Chain Crystal (MC) (Morelli). Elastic segments were distended and exposed for eight minutes, twice a day with interval of 12 hours to cigarette combustion smoke. Elastic tension was evaluated at baseline, 7, 14 and 21 days. Results: the findings have shown that all elastics presented progressive tension reduction over the period evaluated. Statistically significant differences were evidenced from the baseline to 7 days and from 14 to 21 days period. The OTP and OTPB elastics presented greater initial tension when compared to the MG and MC elastics. This pattern was reproduced throughout the study periods. When test groups were compared to the control in the period of 21 days, it was observed that cigars combustion smoke reduced in a statistically significant manner the elastic strength in all groups tested. Relative comparisons between the tested samples and control in the period of 21 days indicated that smoke exposure promoted strength loss that varied from 7% (OTP) to 12% (OTPB). Conclusion: experimental exposure to cigarettes combustion smoke contributed for the strength degradation of orthodontic chain elastics in the period of 21 days.

Topological States Due to Third‐Neighbor Coupling in Diatomic Linear Elastic Chains

The vibrations of a diatomic linear chain exhibit two bands, the acoustic and the optical one. In the case of equal masses and nearest‐neighbor spring constants, no gap exists. The effects of nearest, next‐nearest, and third‐nearest neighbor coupling with different spring constants are analyzed. Nearest neighbor coupling leads to two topologically different bulk states with winding numbers ν = 0 and −1. Next‐nearest neighbor coupling does not change the topological properties and introduces only a trivial “Semenov” gap. Third‐nearest neighbor coupling leads to four distinct topological bulk phases with winding numbers .

Controlling incisor torque with completely customized lingual appliances.

PurposeTo test the null hypothesis of no significant deviation between the center of rotation (CROT) and the center of resistance (CRES) during space closure in Angle class II division 2 subjects achieved using a completely customized lingual appliance (CCLA) in combination with class II elastics and elastic chains.MethodsThis retrospective study included 29 patients (male/female 11/18; mean age 15.6 [13–27] years) with inclusion criteria of an Angle class II/2 occlusion of least of half of a cusp, maxillary dental arch spacing, completed CCLA treatment (WIN, DW Lingual Systems, Bad Essen, Germany) in one center with a standardized archwire sequence and use of class II elastics and elastic chains only. Maxillary incisor root inclination was assessed by X‑ray superimpositions of the maxilla at the beginning (T1) and the end (T3) of CCLA treatment. Using Keynote software (Apple®, Cupertino, CA, USA), the incisor’s CROT was assessed with the point of intersection of the incisor axes (T1; T3) following vertical correction of overbite changes. CRES was defined at 36% of the incisor’s apex–incisal edge distance.ResultsThe null hypothesis was rejected: the mean CROT − CRES difference was 52.6% (p < 0.001). The mean CROT was located at 88.6% (min–max 51–100%) of the incisor’s apex–incisal edge distance. Although 6.9% of CROT were located between the CRES and the alveolar crest, the vast majority (93.1%) were assessed between the alveolar crest and the incisal edge, or beyond.ConclusionCCLAs can create upper incisor palatal root torque even in cases in which lingually oriented forces applied incisally to the center of resistance of the upper incisors counteract these intended root movements.

A Customized Impression Technique for Highly Placed Mal-Aligned Implant for a Hybrid Over Denture Patient: A Case Report

A hybrid implant denture is a fixed prosthesis over a metal framework and engaged by screws into the implant abutments. The anterior and posterior part of a mandibular hybrid denture is rigid on implants. Implant supported hybrid prosthesis provide satisfactory results on the mastication, esthetics and phonetics. This article describes a customized impression technique for highly mal aligned placed implants for hybrid implant denture. The total of five implants was present in the mandibular arch. Author advocates surveying of mal aligned implant analogue cast. The current technique depicts a customized resin impression tray with open border at two sites that concomitant at highly mal aligned implant position (canine region). Technique also uses the hard elastic chain for splinting of impression analogue. Final impression is recorded with single putty wash technique with polyvinyl siloxane elastomeric material. Although, technique is quite clinical sensitive. Asserting over this technique, it eliminates the use of transmucosal or multi unit abutments. This advocated technique is also economical for both clinician and patient. Impression was quite satisfactory.

Effects of 6 different chemical treatments on force kinetics of memory elastic chains versus conventional chains: An in vitro study

Effects of different oral hygiene controls on force kinetics of memory elastic chains are not assessed adequately or in the case of many oral care products, non-existent. This study assessed these. This in-vitro study was performed on 647 observations of 132 elastic chains assessed at 5 intervals. In each of the treatments (artificial saliva, fluoride, OralB mouthrinse, whitening OralB mouthrinse, toothpaste, and whitening toothpaste), 11 memory and 11 conventional chains were tested. Chains were stretched for 100%; their initial force was measured (g), and immersed in artificial saliva at 37°C. For treatments other than artificial saliva, the specimens were removed from the saliva twice daily and the main treatment was applied. After washing with distilled water, they were immersed back in artificial saliva. At the days 1st, 7th, 14th, and 28th, their force was re-measured. Data were analysed statistically (α=0.05). Force degradation of elastic chains was observed in both memory/conventional types (P=0.000) although memory chains showed slightly less declines especially in the beginning days. The interaction of treatment and time was significant (P=0.000) meaning that different treatments caused different rates of force decay, with fluoride having the fastest drop rate followed by whitening toothpaste. However, the difference among 5 intervals of time was not significant (P=0.569). When elastic types were assessed separately, this variable as well became significant (P≤0.002). One-sample t-test showed that all final residual forces (28th day) were either above 150g or at its level. Chain force degrades over time but stays sufficient for bodily tooth movement after 4 weeks. Memory chains are preferable as they provide greater forces for longer durations. Fluoride mouthwash followed by whitening toothpaste cause the most rapid declines. Both chain types still retained adequate forces after 4 weeks, even after treatment with fluoride or whitening toothpaste.

Prevalence of Oral Microbial Flora during Orthodontic Space Closure: A Pilot Study

Introduction: Orthodontic treatment with fixed appliances especially during the retraction stage makes it challenging to maintain the oral hygiene. Attachments used, such as elastic chains, loops and springs, result in changes in the oral environment due to the accumulation of plaque and increase in the levels of bacterial count mainly Streptococcus mutans and Lactobacilli species. Aim: To determine the prevalence of oral microbial flora during orthodontic space closure. Materials and Methods: This was a cross-sectional pilot study conducted during the month of December 2019 which consisted of eight patients who were randomly selected among the age group of 18-25 years. Mean and SD of age in Males (4) and Females (4) were 22±2.16 years and 22.25±1.70 years, respectively and had reported to the Department of Orthodontics of a private dental college, Saveetha Dental College. In each patient, after 6-8 months of orthodontic treatment, plaque samples were collected only once around the orthodontic brackets at the cervical aspect of the maxillary lateral incisor, maxillary premolar, mandibular canine, mandibular premolar in 1st, 2nd, 3rd, and 4th quadrant respectively, by the method of cotton swabbing for the evaluation of micro flora. Independent paired t-test and One-way ANOVA with Post-hoc Tukey HSD test were done to estimate the prevalence of microorganisms at different sites. Results: Independent paired t-test showed highly significant differences in the levels of Streptococcus mutans when compared to Lactobacillus (p&lt;0.001) with mean values of 4.8±2.5 and 23.1±9.2 for Streptococcus and Lactobacillus, respectively. One-way ANOVA with Post-hoc Turkey HSD analysis showed significant difference at the region of maxillary lateral incisor compared to other sites whereas Lactobacillishowed no significant differences between the various sites tested (p-value&lt;0.001). Kappa statistics was performed which revealed an inter examiner reliability of 0.91. Conclusion: During orthodontic space closure, bacterial count of Streptococcus mutans showed a statistically significant difference between different sites (maxillary lateral incisor, mandibular canines, maxillary and mandibular premolars) with highest being the maxillary incisor region followed by that of mandibular canines. However, the incidence of Lactobacillusacidophilus did not show any difference between the various sites evaluated.

Exploiting Giant-Pore Systems of Nanosized MIL-101 in PDMS Matrix for Facilitated Reverse-Selective Hydrocarbon Transport.

Membrane gas separation offers high energy efficiency, easy operation, and reduced environmental impacts for vast hydrocarbon recovery in the petrochemical industry. However, the recovery of real light hydrocarbon mixtures (e.g., olefin/nitrogen) remains challenging for lack of high-performance membranes with sufficient reverse selectivity (large molecules permeate faster) and permeability. Here, we report the incorporation of fine-tuned, giant-pore featured MIL-101 nanocrystals into rubbery polymers to fabricate hybrid membranes, which successfully exploited the giant-pore channels and large sorption volume of the MIL-101 pore system. The synthesized MIL-101/poly(dimethylsiloxane) (PDMS) hybrid membranes demonstrated remarkably simultaneous improvement of gas permeance and separation factor for the model gas mixture propylene/nitrogen. Compared with the pristine PDMS, the propylene permeance and separation factor could be improved by more than 50% by adjusting MIL-101 loading and operating conditions. By consulting molecular simulations and gas sorption analysis, we verified that the giant-pore system of MIL-101 and the elastic PDMS chains exhibited a synergistic effect on improving both hydrocarbon solution and diffusion. Pore properties of MIL-101 contributed favorably to accelerated propylene diffusion in MIL-101 that is 236% faster than that in PDMS. In the meantime, MIL-101 reinforced the hydrocarbon solution additionally to PDMS, which further facilitated hydrocarbon transport.

ASSESSMENT OF LEPTIN CONCENTRATION IN GINGIVAL CREVICULAR FLUID (GCF) DURING ORTHODONTIC TOOTH MOVEMENT

The numbers of patients undergoing orthodontic treatment have increased spectacularly from past several decades. During orthodontic tooth movement the early response of periodontal tissues to mechanical stress is an acute inflammatory reaction. Mechanical stress from orthodontic appliances is believed to induce cells in the periodontal ligament (PDL) to form biologically active substances, such as enzymes and cytokines, responsible for connective tissue remodeling. Biochemical analysis of the gingival crevicular fluid (GCF) has provided a non-invasive model for investigating the cellular response of the underlying PDL during orthodontic tooth movement in vivo. In GCF, several substances such as interleukin, tumor necrosis factor, leptin, osteoprotegerin and alkaline phosphatase have been found to be significantly elevated in teeth under orthodontic forces compared with untreated control teeth. [14] Hence due to the above relevance the present study was planned for Assessment of Leptin Concentration in Gingival Crevicular Fluid (GCF) during Orthodontic Tooth Movement.&#x0D; The present study was planned in Department of Private Practioner, Swastik Dental Clinic and Orthodontic Centre Gaya. Total 10 cases of orthodontic of age 13 – 15 years were evaluated in the present study. For each subject, a maxillary cuspid undergoing distal orthodontic tooth movement was used as an experimental tooth, and the contralateral cuspids served as control tooth. Orthodontic brackets were placed on the canines. Experimental canines were moved in the distal direction through an archwire by use of an elastic chain exerting an initial force of 250 g. The amount of tooth movement for each tooth was measured with digimaticcalipers. At the distal aspect of experimental and control teeth, GCF was collected for subsequent analysis and the following examinations of the periodontium were conducted: Probing depth, presence or absence of plaque, and bleeding on probing. The collection and examinations were conducted immediately before activation and at 1 hr, 1 day, and 7days after the initiation of tooth movement.&#x0D; The data generated from the present study concludes that concentration of leptin in the GCF is decreased by orthodontic tooth movement. Leptin may be one of the mediators associated with orthodontic tooth movement. Orthodontic tooth movement can be carried out without any significant destructive changes in investing tissues of the teeth provided oral hygiene is properly maintained.&#x0D; Keywords: Leptin Gingival crevicular fluid, GCF, orthodontic, etc.

Dentoalveolar Distalisation in Class III Skeletal Base Using Buccal Shelf Mini-implants - A Case Report

Before the advent of skeletal anchorage distalisation of the lower arch was considered cumbersome. Individual lower molar distalisation followed by retraction into the distalised space created is very time-consuming. Therefore, to reduce the treatment duration lower arch distalisation can be attempted by using buccal shelf screws. Here we present a case of Angle’s Class III malocclusion which has been treated effectively with distalisation of lower arch using 2 buccal shelf screws (2x12mm) with elastic chains following lower third molars extraction. We achieved full arch distalisation of 3.5mm bilaterally in a span of 1.5 months into a class I molar and canine relationship with normal overjet and overbite. Total treatment duration was of 17 months. These results were stable. There were no changes in vertical facial dimensions.

Outcome of orthodontic treatment in subjects with periodontal disease. Part III: a CBCT study of external apical root resorption.

No evidence is present on the risk for external apical root resorption (EARR) during orthodontic treatment (OT) of adult patients with periodontal disease. To examine EARR after OT in subjects with periodontal disease and to analyse how intrusion and change in inclination of the most proclined maxillary incisors influence EARR. The study included 50 patients with periodontal disease. Sub-gingival debridement by ultrasonic instrumentation supplemented with hand instruments was performed by experienced dental hygienist after baseline examination for all patients. For the control group, final periodontal treatment (PT) was performed before orthodontic tooth movement. For the test group patients, final PT was performed after levelling and alignment phases were finished, before the active space closure with elastic chain and/or inter-arch elastic traction for sagittal correction was started. OT was performed with a straight-wire appliance. Micro-implants or implants were used for posterior anchorage. Cone beam computed tomography examinations were performed before and after OT. EARR of all single-rooted teeth were measured. EARR of the most proclined maxillary incisor was related to intrusion and change in inclination angle. EARR after OT was observed in median 80.7 per cent (interquartile range 22.02) of single-rooted teeth [mean 1.2 (standard deviation 0.44) mm]. In 82.3 per cent of teeth, EARR was 2 mm or less. Severe EARR was found in 8 per cent of patients and five maxillary incisors (less than 1 per cent of all teeth). The amount of intrusion and change in inclination angle of the most proclined maxillary central incisor influenced the extent of EARR. Mean EARR was significantly higher when OT lasted more than 18 months (P = 0.02). OT in conjunction with PT in periodontal patients resulted in EARR in 81 per cent of all single-rooted teeth. Intrusion and change in inclination angle of the most proclined maxillary central incisor influenced the extent of EARR, as did longer OT.

The effect of immersion different dietary media on the stretched clear elas-tic chains: An in vitro study

Discoloration of clear elastic modules and chains remains an issue which concerns both orthodontics and patients when the increasing demand on esthetic orthodontic appliances. This study was conducted for evaluating the effect of exposing stretched clear elastic chains to three types of dietary media (turmeric, tea and coffee) from six different companies (Ortho Technology, Opal, Ortho Organizer, American Orthodontics, Ormco and G&amp;H). The short type elastomeric chains were cutting about 960 of its lengths from six different companies; 160 pieces from each brand. The specimens were stretched 50%, placed on plastic boards, and incubating at (37°C) in water for (1) day, (7) days, (14) days and (28) days. Once a day, the cutting pieces were immersed in the dietary testing media for ten minutes, washed and then returned to the water container. Color measurements were made before and after incubation of the specimens. The data were statistically analysed using ANOVA and LSD tests. Elastic chains from Ormco, Ortho Organizers and Ortho Technology had the least prone to discoloration, and AO, Opal and G&amp;H companies had the most brands prone to discoloration. Tea, coffee and turmeric solutions discolored elastomeric chains from all companies in a variable degree. However, turmeric caused significantly more discoloration, followed by tea and least by coffee. Most of the discoloration caused by turmeric is in the first day and reaches a plateau at a week, while the amount of discoloration caused by tea and coffee increases gradually to peak at (28) days. Consumption of certain dietary media such as tea, turmeric and coffee caused discoloration of clear elastomeric chains. The range of discoloration increased over time.

New design for unilateral upper molar distalization with bone anchorage system

Molar distalization is considered as a good approach for creating space. Conventional methods were depended on patient compliance but with se of mini screw, tooth movement are done more rapidly, easily and non-compliance. Our design is useful for unilateral upper molar distalization by modified power arm that is connected to mini screw by elastic chain.

Skeletal open bite with amelogenesis imperfecta treated with compression osteogenesis: a case report

BackgroundWe successfully treated a 37-year-old male who had skeletal open bite with severe amelogenesis imperfecta (AI) with orthodontics, compression osteogenesis, and prosthodontics.Case presentationThe patient was diagnosed with severe anterior open bite caused by severe AI. Corticotomy was performed on both buccal and palatal sides of the molar regions, and anchor plates were placed onto the bilateral zygomatic buttress and the center of the hard palate. After corticotomy, posterior maxillary segments were moved 3.5 mm superiorly to correct skeletal open bite with elastic chains. After 8-month, overbite had decreased by 2.0 mm. After further 5 months of prosthodontic preparation, orthodontic appliances were removed, and provisional crowns were set on all teeth. The anterior open bite was corrected, and ideal occlusion with a Class I molar relationship was achieved. The upper first molars were intruded 3.5 mm, resulting in 3.0o counter-clockwise rotation of the mandible. The total active treatment period was 16 months. Acceptable occlusion with a good facial profile was well maintained throughout the 8-year retention period.ConclusionsOur results indicate long-term stability after interdisciplinary treatment combining orthodontics, oral surgery, and prosthodontics in a patient with severe anterior open bite and AI.

Comparative evaluation of speed of orthodontic tooth movement with or without piezocision technique: An In vivo study

Background: Last decade has seen a surge of many innovative techniques aimed at decreasing the length of orthodontic treatment. In this study, the efficiency of canine retraction between piezocision and conventional retraction group has been evaluated and compared. Materials and Methods: A total of ten patients (above 18 years) with Class II division I malocclusion or bimaxillary protrusion which requires individual canine retraction after maxillary first premolar extractions were included in the study. Each patient's maxillary arch was divided into the right and left quadrants. Experimental and conventional sides were randomly allocated. The incisions were given through the periosteum using a piezosurgical knife on the experimental side. Bilaterally, in both the groups, canine retraction was initiated using elastic chain applying 120 g of force on both sides. Follow-up was done every 2 weeks for activation. Results: As compared to the conventional approach, piezocision is 1.5 times faster. Conclusion: Piezocision is an efficient technique that aids an orthodontist to accomplish speedy orthodontic tooth movement without other detriments of the substantially time-consuming and traumatic surgical approaches. Other advantages include decreased surgical procedural time and nominal postoperative discomfort to the patients.

Direct Observation of Large Deformation and Fracture Behavior at the Crack Tip of Slide-Ring Gel

Slide-ring gel is a highly deformable polymer gel prepared by cross-linking rings on polyrotaxanes, in which ring molecules are threaded onto a linear polymer chain. The remarkable extensibility of SR gels is due to the stress equalization effect caused by the sliding of cross-links on polymer chains. We directly observed the stress equalization effect by magnifying the instinctive micron-scale defect to artificial millimeter-scale crack and then mapping the crack tip stress field based on photoelasticity. By reducing coverage of rings on polymer chains in SR gels, obvious crack blunting and delayed crack growth are observed. Highly elongated non-linear “cohesive zone” with length of 0.6 mm and width less than 0.1 mm occurs ahead of crack tip before crack propagation. Our results show that SR gels with low ring coverage have large cohesive strength to survive large deformation before elastic chains rupture, which is essentially derived from the sliding of the cross-links that adjusts strand length automatically to equalize stress in the network.

Preferential Sampling of Elastic Chains in Turbulent Flows.

A string of tracers interacting elastically in a turbulent flow is shown to have a dramatically different behavior when compared to the noninteracting case. In particular, such an elastic chain shows strong preferential sampling of the turbulent flow unlike the usual tracer limit: An elastic chain is trapped in the vortical regions. The degree of preferential sampling and its dependence on the elasticity of the chain is quantified via the Okubo-Weiss parameter. The effect of modifying the deformability of the chain via the number of links that form it is also examined.

Clinical Outcomes Utilizing a "Modified Latham" Appliance for Presurgical Infant Orthopedics in Patients With Unilateral Complete Cleft Lip and Palate.

Presurgical infant orthopedic manipulation is utilized prior to cleft lip/nasal repair to facilitate a gingivoperiosteoplasty (GPP) and primary nasolabial repairs. The Latham dentomaxillary advancement appliance uses a screw that must be tightened daily to approximate the cleft segments in unilateral complete clefts. Our cleft center has been utilizing a "modified Latham" appliance since 1987, including an orthodontic elastic power chain to close the gap in a shorter amount of time. We performed a retrospective chart review of all patients undergoing treatment at Johns Hopkins All Children's Hospital (JHACH) with a unilateral complete cleft lip and palate between 1987 and 2017. Patients were identified by the International Classification of Diseases, Ninth Revision code (749.21). The majority of the patients represent the experience of the senior authors (E.R. and R.F.). Two hundred and eighty-one patients with unilateral complete cleft lip/palate were identified. Seventy-five patients were treated with a "modified Latham" appliance prior to their lip repair. The "modified Latham" appliance remained in place on average 20.6 days (range: 4-82), and average hospital stay after placement was 1.18 days. Nearly 96% of patients underwent a successful GPP at the time of nasolabial repair. Modification of the Latham appliance by utilizing an elastic power chain and eliminating the screw allows rapid closure of the alveolar cleft with limited need for adjustments and outpatient visits. Direct approximation of the palatal segments allows successful completion of a GPP in 95.9% of patients with limited dissection.

Examination of postextraction space closure speed using elastic chains and NiTi closed coil springs

Summary Introduction In everyday clinical practice, we often encounter a lack of space for placing all the teeth present into dental arch; therefore it is often recommended to extract teeth within orthodontic treatment. In clinical practice, the most commonly used methods of closing space after are elastic chains and NiTi closed spiral springs. The aim of this paper was to compare postextraction space closure speed using two different sliding mechanisms, NiTi closed coil springs and elastic chains within treatment with fixed orthodontic appliances. Material and Method The total sample in this study consisted of 46 postexstraction spaces in 23 patients indicated for the extraction of first premolars using treatment with fixed orthodontic appliances. Two sliding mechanisms, NiTi closed coil spring and elastic chains were applied to postextraction space closure. Postextraction spaces were monitored for 4 months with appointments every 4 weeks. During appointments mechanisms were activated and digital caliper was used to measure the width of the postextraction space. Results The results showed that NiTi closed coil springs method achieved greater reduction in postexstraction space (3.94 mm) while with elastic chain method the closure of 3.10 mm was achieved. The total difference between these two methods in the observed period was 0.84mm and no statistically significant difference was found (p&gt; 0.05). The lowest value for NiTi closed springs was 2.19 mm, while for the elastic chain it was 1.29 mm. The best postextraction space closure was 5.70 mm and it was completed using NiTi closed springs while for elastic chain the best value was 4.80 mm. Conclusion: NiTi closed coil springs lead to faster closure of postextraction spaces in relation to elastic chain. Since this difference is minimal, in practice, both methods can be used equally.