NiTi Closed Coil Springs Research Articles

Analysis of sliding mechanics force degradation during postextraction space closure

Introduction. Due to its simplicity, sliding mechanism is very often used in clinical practice for post-extraction space closure, however, the efficiency of this method may be reduced due to friction and changes in the properties of the materials used in this method. The most commonly used methods of sliding mechanics are nickel titanium (NiTi) closed coil spring and elastic chain. The aim of this study was to analyze force degradation in the application of nickel titanium closed coil springs and elastic chains during post-extraction space closure within treatment with fixed orthodontic appliances. Material and Methods. The total sample in this study consisted of 78 post-extraction spaces in patients who were indicated for extraction of first premolars and treatment with fixed orthodontic appliances. Nickel titanium closed coil springs and elastic chains were used to close the post-extraction spaces. Post-extraction spaces were monitored for 6 months with follow up examinations every 4 weeks. Measurements of initial force, at the beginning of mechanism activation and residual force in the observation period were performed during control examinations. Results. Results of this research showed that with both methods of sliding mechanism there was a significant decrease in the observation period. When using NiTi closed coil springs, the value of average initial force at control examination was between 189.00-210.25 g, while residual was in the range of 117.56-133.50 g that NiTi closed coil springs kept an average 61.57% of initial force. The average initial force on the control examinations for elastic chains was between 184.5-205.38 g, while residual force was in range of 100.39-113.00 g, that elastic chains retained an average 53.41% of initial force. Conclusion. There was a significant force degradation between inspections, when sliding mechanics were applied. The loss of force between activation phases of NiTi closed coil springs was smaller compared to the forces produced by elastic chains.

Canine and molar movement, rotation and tipping by NiTi coils versus elastomeric chains in first maxillary premolar extraction orthodontic adolescents: A randomized split-mouth study

The primary objective was to compare canine and molar movement between NiTi coil and elastomeric chains. The secondary objective was to compare the side effects of these techniques (rotation and tipping). This single-blind randomized split-mouth clinical trial was done prospectively. Healthy patients who needed extraction of the first maxillary premolars and did not require anchorage reinforcement techniques for orthodontic treatment were included. Following initial levelling and alignment a dental cast and panoramic radiographs were taken (pre-space closure documents) and canine retraction was done using elastomeric chains on one side and NiTi closed coil spring on the other side. After four months, the same documents were taken and movement (mm), as well as rotation (degree) and tipping (degree) of canines and first molars, were calculated by comparison of pre and post space closure documents by a blinded examiner. Data were analysed by independent samples t-test and Mann-Whitney U test with a significance level of 0.0125. Overall 20 patients completed the study. The average canine movement was 3.88 and 5.45mm (distal movement) in elastomeric chains and NiTi coil groups, respectively (P=0.001). For molars, the movement was 1.20 and 1.15mm (mesial movement), respectively (P=0.529). The mean rotation of the canine in elastomeric chains and NiTi coil groups were 4.50° and 7.43° (mesiobuccal rotation), respectively (P=0.006). For the molars, the mean rotation was 0.23° and 1.90° (mesiolingual rotation), respectively (P=0.307). Average tipping of the canine in elastomeric chains and NiTi coil groups were 4.52° and 7.55° (distal tipping), respectively (P=0.011). For the molars, the numbers were 1.45° and 4.80° (mesial tipping), respectively (P=0.028). Canine retraction by NiTi coil springs is faster compared to elastomeric powerchains with the cost of more canine tipping and rotation and more molar tipping. No significant difference was found in molar movement, rotation and tipping between the two techniques.

Space Closure Rate in Mandibular Canine Retraction by Ni-Ti Closed Coil Spring: A Clinical Trial

Introduction: In Majority of patients seeking orthodontic treatment, teeth must be extracted in order to obtain proper esthetics, occlusion, and stability as well as extraction of teeth is often a need to close residual space, after the initial decrowding and aligning. Pre adjusted fixed orthodontic appliances commonly utilize sliding mechanics for space closure with different types of force delivery systems. A variety of materials have been used as force delivery systems to close spaces between teeth as in the case of canine retraction after the extraction of premolars. Among all sliding or frictionless methods of canine retraction, super-elastic nickel titanium coil spring has a particular property in producing light continuous force at a long range of action, compared with previously available materials. Nickel-titanium closed coil spring, with a continuous action, might have some advantages in fixed appliance space closure mechanics. Materials and Methods: Over the period of one year from May 2015 to April 2016, this clinical trial was carried out and A total number of 20 patients (40 quadrants), who required canine retraction into first premolar extraction sites as part of their orthodontic treatment in the Department of Orthodontics of BSMMU selected as study population. The quadrants were affixed by nickel titanium closed coil springs (medium force, Ni-Ti extension spring, Ormco) with 200gm force measured by Correx Tension Gauge. Space closure was measured by means of direct measurement from the mesial surface of mesial wing of the 2nd premolar bracket and the distal surface of distal wing of the canine bracket with digital Vernier Calipers. Results: Mean space closer rate in mandibular canine retraction was 1.07 ± 0.12 mm/month by nickel-titanium (Ni-Ti) closed coil spring method with p value<0.001. Conclusion: This study revealed that space closer rate in mandibular canine retraction by nickel-titanium (Ni-Ti) closed coil spring is 1.07 ± 0.12 mm/month. Medicine Today 2021 Vol.33(2): 90-93

Comparison of force decay pattern in orthodontic elastomeric chains and NiTi closed coil springs, affected by five different mouthwashes: An in vitro Study

Background: The aim of this study was to compare the force decay pattern of elastomeric chains and NiTi coil springs which were exposed to five different commercially available mouthwashes.Methods: In this in vitro study, 60 pieces of elastomeric chain (EC) and 60 NiTi closed coil springs (CS) were divided into 6 groups. The specimens were exposed to one of these mouthwashes twice a day for 60 seconds: Listerine, chlorhexidine, Orthokin, Persica, fluoride and artificial saliva as the control group. The elastomeric chains and NiTi springs were stretched so that they exert the initial force of 250 gr. Their force was measured on the 1, 7, 14 and 28 following days by means of a digital gauge.Results: Elastomeric chains and coil springs had force decrease over time, but EC' force reduction was greater with the highest reduction rate in the first week. However, in the CS group, the force decrease wasn't statistically significant in the first two weeks. After 28 days in the control groups, 49.8% of the initial force was remained in ECs while the value was 93.3% for CSs. In comparison between mouthwashes, in EC groups, in all mouthwashes except Persica, the remained force was statistically less than control group.Conclusion: Force degradation of elastomeric chains could be exacerbated by use of mouthwashes. About coil springs, force decay was also observed. However, it was not statistically significant. Force reduction was detectable after four weeks of coil springs usage, but in EC groups, the greatest reduction was after the first week.

Intermittent vibratory stimulation to accelerate tooth movement: A clinical study

Vibratory stimulus is non-invasive and non-pharmacologic method for acceleration of Orthodontic tooth movement in adult patients. As powered toothbrush can provide cheaper alternative to Acceledent (a patent and expensive device) it was decided to evaluate the effectiveness of vibratory stimulation from powered toothbrush as a method of accelerating individual canine retraction.Sample consisted of 24 patients undergoing fixed Orthodontic treatment, in whom separate canine retraction was planned after extraction of all first premolars using NiTi closed coil spring. Force was standardized as 150 grams and checked at each appointment using Dontrix gauge. Following split mouth study design, right side was the experimental side where patients were asked to apply the vibratory stimulus through powered tooth brush (133Hz frequency) for 6 minutes (3 minutes labially and 3 minutes palatally) three times daily at regular intervals for a period of 3 months. Study models were taken at T0 (start of canine retraction), T1 (after 1st month), T2 (after 2nd month) and T3 (after 3rd month). Mean amount of canine movement and molar movement with respect to 3rd palatine rugae was measured on Digimizer software on both the sides for different time intervals.Statistically significant increase in canine movement was seen for total canine movement (T0-T3), movement from T0-T1 and from T2-T3. There was statistically insignificant difference in mesial movement of molars for different time intervals.There was an increased rate of canine movement on the side of vibratory stimulation (right side) in comparison to the control side (left side) for all time intervals and can be used to decrease treatment time in adults.

Effects of submucosally administered platelet-rich plasma on the rate of tooth movement.

To evaluate the effects of submucosally administered platelet-rich plasma (PRP) on the rate of maxillary canine retraction. Levels of soluble receptor activator of nuclear factor-κb ligand (sRANKL) and osteoprotegerin (OPG) in the gingival crevicular fluid (GCF) were also measured over 2 months. This split-mouth trial involved 20 sites in 10 subjects randomly assigned to PRP (experimental) side and control side. After alignment, the freshly prepared PRP was injected submucosally distal to the experimental side maxillary canine, and retraction was performed using NiTi closed-coil springs (150 g) on 0.019 × 0.025-inch stainless steel wire. The rate of canine movement was assessed using digital model superimposition at 0, 30, and 60 days. The OPG and sRANKL were assayed using enzyme-linked immunosorbent assay from GCF collected at 0, 1, 7, 21, 30, and 60 days. Twenty sites were analyzed using paired t test. The rate of tooth movement increased significantly by 35% on the PRP side compared with the control side in the first month (P = .0001) and by 14% at the end of the second month (P = .015). Using the Mann-Whitney U test, OPG levels were found to be significantly decreased on the 7th (P = .003) and 30th day on the PRP side (P = .01), while sRANKL became detectable by the third week postinjection on the PRP side (P = .069). Submucosal injection of platelet-rich plasma significantly increased tooth movement during the 60-day observation period. Local injection of PRP significantly altered the levels of OPG and sRANKL in GCF.

Comparison of the efficacy of two-time versus one-time micro-osteoperforation on maxillary canine retraction in orthodontic patients: A split-mouth randomized controlled clinical trial

Micro-osteoperforation (MOP), a minimally invasive technique for accelerating the rate of orthodontic tooth movement has been research extensively, but with varied clinical results. To compare the efficacy of one-time versus two-time micro-osteoperforation on the rate of maxillary canine retraction, its influence on anchorage loss, canine angulation and the levels of interleukin (IL-1β) in gingival crevicular fluid (GCF). The split-mouth study included 16 patients in which the left and right sides were randomly allocated to the control side (one-time MOP) and experimental side (two-time MOP). MOP was performed on both sides distal to the maxillary canines and canine retraction was carried out using NiTi closed coil springs (150gm) and direct anchorage with miniscrew implants. The second MOP was performed on experimental side one month after the first MOP. The rate of canine movement was assessed using 3D model superimposition over a period of six months. The type of tooth movement, anchorage loss and levels of IL-1β were also evaluated. Sixteen patients (mean age, 17.87±3.34 years) were analysed for a rate of canine retraction, anchorage loss, and type of tooth movement, while 15 patients were analysed for IL-1β. The rate was significantly higher on two-time MOP side after two months (P<0.001). No statistical difference was found in anchorage loss and controlled tipping of canines was observed. The IL-1β levels immediately after 2nd MOP were significantly higher than 1st MOP (P<0.001). The two-time intervention of MOP is more efficacious than one-time MOP in accelerating tooth movement.

Comparison of the rate of maxillary canine retraction with or without modified corticotomy facilitated orthodontic treatment

Objectives: The aim of the study was to evaluate and compare the rate of maxillary canine retraction in cases with modified corticotomy versus without modified corticotomy. Clinical interventional study. Split mouth design was used. Materials and Methods: A sample size of ten patients and 20 sites were selected within the age group of 18–35 years following all criteria of the study. Before orthodontic leveling and alignment, upper first premolar extraction was carried out under local anesthesia. Pre-treatment OPG and IOPA were taken in relation to the maxillary canine and maxillary second premolar teeth. One extraction side was considered as the experimental site and contralateral side as control. Leveling and alignment were started with wire sequence. After modified corticotomy procedure, the canine retraction was started with 8 mm NiTi closed coil spring. The amount of tooth movement was recorded with the help of a Digital Vernier Caliper at an interval of 1 month till the completion of canine retraction. Results: Paired t-test showed higher mean velocity of tooth movement in modified corticotomy side (1.07 ± 0.25) as compared to the conventional side (0.91 ± 0.24), (P &lt; 0.001). Conclusion: The modified corticotomy technique serves as an effective treatment modality for adults seeking orthodontic treatment with increased rate of orthodontic canine retraction.

Does local injection of reveromycin A inhibit tooth movement without causing systemic side effects?

To determine the feasibility of local inhibition of osteoclast activity and control of tooth movement with local intraoral reveromycin A (RMA) injection in model mice for experimental tooth movement. Eight-week-old wild-type mice (n = 6 per group) were divided into four groups consisting of two non-RMA groups that received normal saline for 14 (14-day non-RMA group) or 21 consecutive days (21-day non-RMA group) and 2 RMA groups that received RMA (1.0 mg/kg of weight) for 14 (14-day RMA group) or 21 consecutive days (21-day RMA group). RMA was injected locally into the buccal mucosa of the left first maxillary molar twice daily starting 3 days before placement of the 10-gf Ni-Ti closed coil spring. Tooth movement distance was analysed using micro-computed tomography. The effects on surrounding alveolar bone were evaluated by measuring the ratio of bone surface area to tissue surface area with haematoxylin-eosin-stained sections and counting the number of osteoclasts in periodontal tissue with TRAP-stained sections. Blood tests were performed and bone volume and trabecular separation at the tibial neck were measured to analyse systemic side effects. Local RMA injection inhibited tooth movement by 40.6 per cent, promoted alveolar bone volume maintenance by 37.4 per cent, and inhibited osteoclast activity around the tooth root at 21 days by 40.8 per cent. Systemic effects on osteoclasts or osteoblasts were not observed. Local injection of RMA enabled control of tooth movement without systemic side effects in a mouse model.

Determination of Optimal Loading Conditions Using Lever Arm and Mini- Implant System for En-masse Retraction in Lingual Orthodontics – A FEM Study

Aim: To evaluate the stress distribution along the periodontal ligament and alveolar bone by various combinations of mini-implants and lever arm used during en-masse retraction of anterior teeth using finite element method.Materialsand Methods: Four three-dimensional finite element models of the bilateral maxillary first premolar extraction casewas constructed. Lingual brackets were (0.018” slot) positioned over the center of the clinical crown. In all four models 150 g of retraction force with the help of the NiTi closed coil springs was applied with different combinations of mini-implants and lever arm. A finite element analysis was then performed to evaluate stress distribution, the principle stress, von Mises stress and displacement of the anterior teeth using ANSYS 12.1 software.Result: In this study the constructed models along with the load application were imported into ANSYS (version 12.1) software for analyzing the displacement and stress distribution corresponding to the force application. The maximum tensile stress of periodontal ligament were observed at distal root apex area of canine in all four models. Variable amount of displacements like lingual crown tipping, lingual root tipping and extrusion were observed in all the models suggesting different combinations of lever arm and mini-implants affect the direction of the tooth displacements in lingual mechanics.Conclusion: In lingual orthodontics tipping movement of crown decreases as the height of lever arm increases. It was also found that when mini-implants were placed at higher position the amount of tipping movement decreases with minimum amount of extrusion seen in central incisor and lateral incisor.

Comprehensive comparison of canine retraction using NiTi closed coil springs vs elastomeric chains.

To compare canine retraction using NiTi closed coil springs vs elastomeric chains comprehensively in a split-mouth randomized controlled trial. The canines in 64 quadrants were randomly retracted into the first premolar extraction spaces using NiTi closed coil springs or elastomeric chains, in the maxilla and mandible. The retraction force was 150 g. Cone beam computed tomography scans and study models were obtained before the start of canine retraction and 6 months later. The rate and total amount of canine retraction, canine rotation, tipping, and root resorption were evaluated. A visual analogue scale was used to evaluate patients' pain experience. The two methods were statistically similar for dental changes, rate of canine retraction, and root resorption. However, patients reported significantly more days of pain with the elastomeric chain compared to the NiTi closed coil springs. Within the constraints of the current study, using either NiTi closed coil springs or elastomeric chains as force delivery systems for canine retraction results in no significant difference in the rate of canine retraction, tipping, rotation, or root resorption. Pain experience during retraction using elastomeric chains is more significant yet needs further investigation.

Three-Dimensional Finite Element Analysis for Stress Distribution During Intrusion and Retraction Using Orthodontic Mini-implants

Background and Objectives: the study was conducted to evaluate the levels of stress produced in and around implants when placed at different sites for retraction and intrusion of maxillary anteriors. The other objective was to evaluate stress levels produced at implant bone interface when mini implants were placed at different angulations at the same site. Materials and Methodology: Finite element model of the maxilla and maxillary dentition was constructed using the CT skull of subject used in the study. All the accessories used like mini-implants, stainless steel wire, coil springs etc were scanned separately for obtaining detailed anatomic features. The force was given between retraction hook and mini -implant using NITI closed coil spring for intrusion and retraction of maxillary anterior teeth. The basic mechanical factors i.e. the stresses developed in mini implant, the angle of insertion of the mini implant into the bone surface were analyzed. Finite Element model was generated by Hyper mesh 9.0 software. Analysis was carried out by using Ansys 12.1 software. Results and Conclusion: All the set objectives were accomplished at the end of the study which included complete closure of extraction space by retraction and intrusion in the models. The following conclusions were drawn: The least stress was seen on an implant at middle third, when inserted at an angle of 800 to the bone surface, with application of 50-100mg of intrusive force on anterior implant and 200 gms of retractive force on posterior implant.

Effect of PTH and corticotomy on implant movement under mechanical force

BackgroundOsseointegrated implants are considered as clinically non-movable. Parathyroid hormone (PTH) is known to play a significant role in the regulation of bone remodeling and in intermittent, low doses, result in osteoanabolic effects. This study aimed to investigate the effects of PTH and corticotomy, both under traction force, on osseointegrated implants.MethodsFour implants—two in each hemimandible—were placed in each of the three study mongrels. Each mongrels were designated as control, normal dose PTH (PTH-1), and high dose PTH (PTH-2) groups, with each groups further subdivided into non-surgery implant and surgery implant. After osseointegration, mechanical force with NiTi closed coil springs (500 g) was applied around each implants. Corticotomy was performed around one of four implants in each mongrels. Parathyroid hormone was administered locally on a weekly basis for 20 weeks. Clinical movement of the implants were evaluated with the superimposed 3D- scanned data, bone- microarchitectural and histologic examinations.ResultsSuperimposition analysis showed continuous movement of the non-surgery implant of PTH-1 group. Movement was further justified with lowest bone implant contact (adjusted BIC; 44.77%) in histomorphometric analysis. Upregulation of bone remodeling around the implant was observed in the normal dose PTH group. In the surgery implants, the remarkably higher adjusted BIC compared to the non-surgery implants indicated increased bone formation around the implant surface.ConclusionThe results indicate that the catabolic and anabolic balance of osseointegrated implants in terms of bone remodeling can be shifted via various interventions including pharmacological, surgical and mechanical force.Clinical relevanceUpregulated bone remodeling by PTH and corticotomy under continuous mechanical force showed the possible implications for the movement of osseointegrated dental implant.

Displacement and stress distribution of Kilroy spring and nickel-titanium closed-coil spring during traction of palatally impacted canine: A 3-dimensional finite element analysis.

To compare the stress distribution and initial displacements during traction of palatally impacted canine between Kilroy and nickel-titanium (NiTi) closed-coil springs by means of the finite element analysis. A finite element method analysis of two traction methods for a maxillary impacted canine. The corresponding periodontal ligaments (PDLs), brackets, molar tubes and a 0.019×0.025-in base stainless-steel (SS) wire were modelled and imported to ANSYS SpaceClaim version 2020 R1. Traction was simulated under two different set-ups with equal force magnitude (60g); (1) the Kilroy spring, which is made of 0.016-inch SS, and (2) the NiTi closed -coil spring. Von Mises stress distributions and initial displacements of the maxillary teeth were analysed. In both mechanics, while the highest stress was seen on the impacted canine (Kilroy, 10.41kPa; NiTi closed-coil, 5.27kPa), the stress distribution decreased as the distance from the impacted canine increased. The Kilroy spring showed a greater total displacement (465.60μm) on the impacted canine. The higher stresses on the adjacent lateral (5.29kPa) and premolar (6.41kPa) occurred with the Kilroy spring. The Kilroy spring yielded higher stresses than the NiTi closed-coil spring on the impacted canine and the adjacent teeth. The difference between distribution of the stresses over the impacted canine induced greater displacement with the Kilroy spring, particularly in the vertical direction.

Effect of Heat Treatment Temperature on the Mechanical Properties of Custom-Made NiTi Closed Coil Springs

To investigate the effects of different temperatures for heat treatment of custom-made NiTi closed coil springs. NiTi closed coil springs (50.8% Ni-49.2%Ti) were manually fabricated around a 0.9mm diameter mandrel and heat treated at temperatures of 400°C, 450°C, and 500°C for 20 minutes. The outer diameter of each specimen was measured to determine the effect of heat treatment temperature on spring geometry. Tensile tests were carried out to measure the force levels at 3, 6, 9, and 12 mm of spring extension. Non-parametric statistical analyses were done to assess and compare the effects of different temperatures of heat treatment on the custom-made orthodontic closed coil springs. Heat treatment at lower temperatures produced larger outer coil diameters than at higher temperatures. Raising the temperature of heat treatment produced significant increases in force levels by 13-18 g especially between 400°C and 500°C at spring extensions of 3, 6 and 9 mm. The highest superelastic ratio of 5.44 was found in the NiTi coil springs that were heat treatment at 500°C for 20 minutes which signifies superelastic tendencies. The mechanical properties of NiTi closed coil springs are influenced by the temperature of heat treatment. The NiTi closed coil springs that were heat treated at 500°C for 20 minutes produce appropriate force levels to display a superelastic tendency for orthodontic use.

Maxillary molar distalization in treatment of angle class II malocclusion growing patients: Uncontrolled clinical trial

This study was conducted to evaluate the clinical effectiveness treatment effects of a simple buccal technique for maxillary molar distalization using direct buccal skeletal anchorage. After sample size calculation, fourteen female patients with bilateral Class II molar relationship (age 11-14 years) were selected from the clinic of the Department of Orthodontics, Faculty of Dentistry, Mansoura University, Egypt. After the application of the eligibility criteria, only eleven patients remained to final evaluation. The criteria included: erupted second maxillary molars, mild to moderate maxillary crowding not exceeding 6mm with/without increased overjet and non-extraction treatment in the lower arch. After alignment and levelling, a miniscrew (1. 8mm diameter - 0. 8mm long) was placed buccally between the maxillary second premolar and the first molar in each side. The maxillary molar distalization was done using 250 grams of force produced from NiTi closed coil spring stretched to a buccal miniscrew. Records including cephalometric x-rays and study casts were taken for all patients before and after molar distalization. Statistical evaluation was performed for the data obtained from analysis of cephalometric tracing and cast photocopies. The maxillary first molars were distalized with a rate of 0. 89±0. 30mm (95% CI 0.76-1.02) (P<0.001) and distalization amount of 4.09±0. 92mm (CI 3.68-4.50) (P<0.001). They were distally tipped by 2.48°±6. 16 (CI -0.26-5.21) (P=0.073) and rotated distopalatally by 11.89°±5.86 with negligible change in their vertical position about 0.11±0.63mm (CI -0.40-0.17) (P=0.411). There was no anchorage loss evident by the distal movement of all the maxillary teeth (P<0.001). Overjet significantly reduced by 0. 86±0. 50 (CI 0.52-1.20) (P=0.004). Maxillary molar distalization using a closed coil and buccal miniscrew is an effective and non-compliance dependent technique in a relatively short time.

Receptor Activator of Nuclear Factor-Kappa Ligand and Osteoprotegerin Expressions on Hyperglycemic Wistar Rats (Rattus Novergicus) During Orthodontic Tooth Movement

Objective: To investigate the differences of receptor activator of nuclear factor- κ B ligand (RANKL) and Osteoprotegerin (OPG) expressions between normoglycemic and hyperglycemic Wistar rats ( Rattus Novergicus ) during Orthodontic Tooth Movement (OTM). Material and Methods: This study was true experimental with post-test group only. Thirty-two healthy male Wistar rats, weighted around 200-250 grams, 12-20 weeks old, were used as OTM animal study. They were divided into 2 groups (n=16), normoglycemic rats (normal blood glucose 80-120 mg/dl) and hyperglycemic rats (>250 mg/dl) induced by Streptozotocin with a dose of 30 mg in PBS injection intraperitoneally. A NiTi closed coil spring was mounted between maxillary first molar and incisors with the light force 10gf/mm 2 in both groups to induce OTM. The studied animals were then terminated on days 1, 3, 6, and 9, respectively, and premaxilla was extracted. RANKL and OPG expression were examined utilizing immunohistochemistry (IHC) analysis. One-way ANOVA and Tukey HSD (p<0.05) were utilized to analyze the differences in the expression of RANKL and OPG between groups . Results: The hyperglycemic group on day 1, 9 rats showed a significant increase in the expression of RANKL, whereas OPG expression decreased significantly on days 1, 3, and 9 . Conclusion: There was a significant increase of RANKL expression and a decrease of OPG expression in hyperglycemic rats as documented immunohistochemically.

A comparative evaluation of rate of retraction and anchorage loss using nickel titanium closed coil spring and active tiebacks during the en-mass retraction in mandibular arch - an in-vivo study

Objective:To compare clinical effectiveness of Nickel Titanium (Ni-Ti) closed coil spring and active tiebacks during space closure in mandibular arch. To compare rate of anterior retraction by using Ni-Ti closed coil spring and active tiebacks in mandibular arch. To compare amount of anchor loss in mandibular arch with Ni-Ti closed coil spring and active tiebacks. Materials and Methods: A total of 20 patients with Class 1 bimaxillary proclination undergoing fixed orthodontic treatment (MBT 0.022 slot) after ?rst premolar extraction will be randomly selected from depatment of Orthodontics & Dentofacial Orthopaedics of K.D. Dental college, and will be divided into two groups for space closure. Patient will be informed about treatment and thesis procedure and consent regarding was taken. The space closure mechanics was allocated to the left or right side of same arch wire in each patient. Group 1 consisted of 10 patients in which right quadrant of maxillary arch, the space closure was done by Ni-Ti closed coil springs in 10 patients and by active ligature on left quadrant of the same 10 patients. Group 2 consisted of same 10 patients in which left quadrant of same arch, the space closure will be done by active ligature in 10 patients and by Ni-Ti closed coil springs on right quadrant of same 10 patients. The amount of anterior retraction, anchorage loss and rate of space closure was measured before start of retraction and patients will be called at six week interval for evaluation of retraction rate as T0, T1, T2, T3,T4. Results will be assessed on cast and Lateral Cephalogram were repeated at T4 for evaluation of anchorage loss. Result: Rate of anterior retraction and amount of anchorage loss was found to be slightly more with niti closed coil spring as compared to that of active tie back. Conclusion: NiTi closed coil springs achieved faster space closure as compared to the active tieback and significant amount of anchorage loss was also noted with NiTi closed

Histomorphometric and Histopathologic Evaluation of the Effects of Systemic Fluoride Intake on Orthodontic Tooth Movement.

Objectives The aim of this study was to determine the effects of systemic fluoride intake on orthodontic tooth movement with histomorphometric and histopathologic methods. Materials and Methods Forty-eight Wistar albino rats were randomly divided into four groups of 12 rats each. Group I received fluoridated water and underwent orthodontic tooth movement. Group II received fluoridated water and did not undergo orthodontic tooth movement. Group III received nonfluoridated water and underwent orthodontic tooth movement. Group IV received nonfluoridated water and did not undergo orthodontic tooth movement. At the beginning of the experiment (T1), impressions were taken from the maxilla of the rats in groups I and III under general anesthesia, and a NiTi closed coil spring appliance was ligated between the left maxillary central incisors and maxillary first molar. The orthodontic force applied was approximately 75 g, and the duration of the experimental period was 18 days. During the experimental period, appliances were controlled daily. At the end of the experimental period (T2), the rats were sacrificed with an overdose of a ketamine/xylasine combination, and their impressions were obtained. The upper first molars were subsequently dissected for histological examination. Incisor–molar distance, number of osteoblasts, number of osteoclasts and periodontal ligament (PDL) space widths on the compression and tension sides were measured. Statistical Analysis All measurements were statistically analyzed with SPSS for Windows version 18.0 (SPSS Inc., Chicago, IL, USA). Repeated measures ANOVA and posthoc Tukey tests were used to compare the groups. Results No statistically significant difference was found with respect to the amount of tooth movement between the fluoridated and nonfluoridated groups ( p > 0.05). Orthodontic force application increased the number of osteoblasts at the tension sides and reduced it at the compression sides ( p < 0.001). An increased number of osteoclasts was observed in the nonfluoridated group relative to the fluoridated group ( p < 0.01). Conclusions No difference was observed with respect to the amount of tooth movement between the fluoridated and nonfluoridated groups. Fluoride significantly reduced the number of osteoclasts in the experimental groups.

Effect of TNF-α-Induced Sclerostin on Osteocytes during Orthodontic Tooth Movement.

Osteocytes are abundant cells in bone, which contribute to bone maintenance. Osteocytes express receptor activator of nuclear factor kappa-B ligand (RANKL) and regulate osteoclast formation. Orthodontic tooth movement (OTM) occurs by osteoclast resorption of alveolar bone. Osteocyte-derived RANKL is critical in bone resorption during OTM. Additionally, tumor necrosis factor-α (TNF-α) is important in osteoclastogenesis during OTM. Sclerostin has been reported to enhance RANKL expression in the MLO-Y4 osteocyte-like cell line. This study investigated the effect of TNF-α on sclerostin expression in osteocytes during OTM. In vitro analysis of primary osteocytes, which were isolated from DMP1-Topaz mice by sorting the Topaz variant of GFP-positive cells, revealed that SOST mRNA expression was increased when osteocytes were cultured with TNF-α and that RANKL mRNA expression was increased when osteocytes were cultured with sclerostin. Moreover, the number of TRAP-positive cells was increased in osteocytes and osteoclast precursors cocultured with sclerostin. In vivo analysis of mouse calvariae that had been subcutaneously injected with phosphate-buffered saline (PBS) or TNF-α revealed that the number of TRAP-positive cells and the percentage of sclerostin-positive osteocytes were higher in the TNF-α group than in the PBS group. Furthermore, the level of SOST mRNA was increased by TNF-α. As an OTM model, a Ni-Ti closed-coil spring connecting the upper incisors and upper-left first molar was placed to move the first molar to the mesial direction in wild-type (WT) mice and TNF receptor 1- and 2-deficient (TNFRsKO) mice. After 6 days of OTM, the percentage of sclerostin-positive osteocytes on the compression side of the first molar in TNFRsKO mice was lower than that in WT mice. In this study, TNF-α increased sclerostin expression in osteocytes, and sclerostin enhanced RANKL expression in osteocytes. Thus, TNF-α may play an important role in sclerostin expression in osteocytes and enhance osteoclast formation during OTM.