NiTi Coil Spring Research Articles

Sustained Protraction Increases Lengthening of the Mandibular Condylar Process Whilst Changes Its Growth Direction in a Rat Model.

In Class II elastics treatment, the mandible is subject to sustained protraction. The study aimed to investigate the morphological and histological changes resulting from sustained mandibular protraction, through establishment of a novel model in rat. Forty-eight 4-week-old male Sprague-Dawley rats were randomly divided into three groups, including the 50 and 100 cN protraction groups, and the control. In the two protraction groups, NiTi coil springs were fixed between the metal bands on the maxillary incisors and mandibular molars to pull the mandible forward. CBCT scans were taken immediately before (T0), 2 weeks (T1) and 4 weeks (T2) after the traction. Histological and immunohistochemical analyses were performed at T1 and T2. Increase of the condylar process length and angular process length were significantly larger in the two protraction groups than that in the control; however, the condylar process angle (∠CPA) was significantly reduced by the protraction at T2, leading to decreased condylar height. The protraction decreased the condylar cartilage thickness at T1, which recovered to the control level at T2, with no significant changes detected in the expression of SRY-related high mobility group-box gene 9 (SOX9) and type II collagen (COL II), two chondrogenic markers. The established rat model is manoeuvrable and reliable, which exerts sustained and measurable mandibular protraction. The sustained protraction increases the lengthening of the mandibular condylar process, but alters its growth direction by causing it to turn downwards.

Friction versus frictionless mechanics during maxillary en-masse retraction in adult patients with Class I bimaxillary dentoalveolar protrusion: a randomized clinical trial.

Extraction space closure is a challenging phase during orthodontic treatment that affects not only the total treatment duration but also the whole treatment outcome. To compare the efficiency of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients with bimaxillary dentoalveolar protrusion. Two-arm parallel group, single-center randomized clinical trial. Thirty-two adult patients with bimaxillary protrusion were recruited and randomly allocated to two different retraction mechanics. A friction group, using NiTi coil springs and a frictionless group using closing T-loops for en-masse retraction. Randomization in a 1:1 ratio was generated by Microsoft Excel. The randomization numbers were secured in opaque sealed envelopes for allocation concealment. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. Activation was done on a monthly basis until complete retraction of anterior segment. The rate of retraction, amount of anchorage loss, the dental, and soft tissue changes were analyzed on digital models and lateral cephalograms taken before retraction and after space closure. The outcome assessor was blinded through data concealment during assessment. Two patients were lost to follow up, so 30 patients completed the trial. The rate of anterior segment retraction was 0.88 ± 0.66mm/month in the frictionless group compared to 0.72 ± 0.36mm/month in the friction group which was statistically significant. Anchorage loss of 1.18 ± 0.72mm in the friction group compared to 1.29 ± 0.55 mm in the frictionless group with no significant difference. Comparable dental and soft tissue changes following en-masse retraction were reported in both groups, with no statistically significant difference. one patient complained of soft tissue swelling following miniscrew insertion, but the swelling disappeared after one week of using mouth wash. The study focused only on the maxillary arch. Both mechanics have successfully achieved the required treatment objectives in patients with bimaxillary dentoalveolar protrusion. Frictionless group showed a faster rate of retraction than the friction group, which was statistically but not clinically significant. Clinicaltrials.gov with the identifier NCT03261024.

Force degradation of two orthodontic accessories analyzed in vivo and in vitro

ObjectiveTo compare force degradation of elastomeric chains and NiTi coil springs in vivo and in vitro, and evaluate the effects of pre-stretched and reused elastomeric chains in the oral cavity during the time.MethodsIn the in vitro groups, 4-unit elastomeric chains and NiTi coil springs with an initial force of 200 g were placed in dry air and artificial saliva. The volunteers wore clear retainers which were used to hold the sample of 4-unit chains, pre-stretched 4-unit chains, and NiTi coil springs with the initial force of 200 g in the in vivo groups. After the first 4 weeks, 4-unit specimens were stretched to 200 g again for another 4 weeks in vivo. The force value and the percentage of force degradation were recorded at each measurement time interval in the in vivo and in vitro groups.ResultsThe force degradation of elastomeric chains was greatest within the initial 4 hours, followed by a more stable phase after 1 week. The average force degradation of 4-unit elastomeric chains after 4 weeks was in vivo (64.8%) > artificial saliva (55.0%) > dry air (46.42%) (P < 0.05). The force degradation of NiTi coil springs in vivo (15.36%) or in artificial saliva (15.8%) was greater than in dry air (7.6%) (P < 0.05). NiTi coil springs presented a gentler force decay than elastomeric chains during the period (P < 0.05). In vivo, the force degradation of pre-stretched and reused elastomeric chains decreased less than the regular style(P < 0.05).ConclusionThe force degradation of the elastomeric chains and NiTi coil springs varied in different environments. NiTi coil springs presented a gentler force decay than elastomeric chains during the period. Orthodontists should consider the force degradation characteristics of orthodontic accessories in clinical practice.

Periodontal ligament and alveolar bone remodeling during long orthodontic tooth movement analyzed by a novel user-independent 3D-methodology

The structural process of bone and periodontal ligament (PDL) remodeling during long-term orthodontic tooth movement (OTM) has not been satisfactorily described yet. Although the mechanism of bone changes in the directly affected alveolar bone has been deeply investigated, detailed knowledge about specific mechanism of PDL remodeling and its interaction with alveolar bone during OTM is missing. This work aims to provide an accurate and user-independent analysis of the alveolar bone and PDL remodeling following a prolonged OTM treatment in mice. Orthodontic forces were applied using a Ni–Ti coil-spring in a split-mouth mice model. After 5 weeks both sides of maxillae were scanned by high-resolution micro-CT. Following a precise tooth movement estimation, an extensive 3D analysis of the alveolar bone adjacent to the first molar were performed to estimate the morphological and compositional parameters. Additionally, changes of PDL were characterized by using a novel 3D model approach. Bone loss and thinning, higher connectivity as well as lower bone mineral density were found in both studied regions. Also, a non-uniformly widened PDL with increased thickness was observed. The extended and novel methodology in this study provides a comprehensive insight about the alveolar bone and PDL remodeling process after a long-duration OTM.

Dentoalveolar and Soft Tissue Changes Following en-Masse Anterior Retraction With Different Force Vectors in Subjects With Bidental Protrusion: A Retrospective Evaluation.

Introduction The aim of the study is to determine the effects of different vertical force vectors acting on dentoalveolar and soft tissues while applying a retraction force using various anchorage sources and their effects on these tissues. Material andmethods Based on the selection criteria, a total of 35 patient case records with Angle's Class I bidental malocclusion and incompetent lips treated with four premolar extractions were included. Retraction was achieved using a NiTi coil spring with two different force vectors. The anchorage in group 1 was enhanced by a transpalatal arch (TPA)and Lower Stabilizing Arch(LSA) in the upper and lower arch, respectively, with a force vector parallel to the occlusal plane,whereas in group 2, the force vector using Temporary Anchorage Devices (TADs) was 15 - 20 degrees to the occlusal plane. The skeletal, dental, and soft tissue were obtained using 40 parameters. Intra-group comparisons between pre- and post-treatment records were conducted using a paired t-test, while inter-group comparisons were conducted using an independent t-test. Result Significant anchor loss was observed in group 1, indicated by mesial movement of molar crowns by (-2.10±0.50) in the maxillary arch and (-1.75±0.38) in the mandibular arch. Distal movement of incisors following premolar extractions with both studied force vectors resulted in an improvement in lip procumbency and incisor inclinations, without any significant skeletal changes.Molar mesial movement was observed in subjects treated with conventional anchorage. Conclusion En masse anterior retraction did lead to anchorage loss when carried out without TADs.Altering the force vector did not produce significant changes in tooth movement along the vertical plane.

Evaluation of the Effect of Oral Vitamin D3 Supplement on Orthodontic Tooth Movement: A Randomized Clinical Trial Study

Aim: One of the problems that orthodontists commonly face is the prolonged duration of the treatment. Therefore, it is important to find an effective method to increase the rate of orthodontic tooth movement (OTM). This study aimed to evaluate the effectiveness of oral administration of vitamin D3 on OTM rates in humans. Materials and Methods: In this randomized clinical trial study, we selected 29 healthy women aged 18–25 years who sought orthodontic treatment and required bilateral maxillary first premolar extraction. Participants were tested to measure the blood levels of vitamin D3 and, based on the outcomes, were divided into three groups: control (without vitamin D3 deficiency; N = 10), placebo ( N = 9), and experiment ( N = 10), both with vitamin D3 deficiency. Subjects of the last two groups, who were randomly assigned, received 50,000 IU (International Unit) vitamin D3 pearls (Dana Pharmaceutical Company, Tabriz, Iran) or a placebo every 2 weeks for 2 months. Inclusion criteria were patients requiring bilateral extraction of the first premolar in the maxilla. The canines were retracted by nickel-titanium (NiTi) coil springs into the extraction sites. At the beginning, after 1 and 2 months, the distance between canine and lateral teeth on both sides was measured to calculate OTM. Results: In the first month ( t (1–2)), the mean values of OTM in the placebo group were higher than the other groups. However, during the second month ( t (2–3)) and overall ( t (1–3)), the experiment group showed a higher OTM. The experiment and control groups were statistically different in all three time periods ( P-value &lt; .05). The difference between the experiment and placebo groups was only significant in t (2–3) ( P-value &lt; .05). Whereas the placebo and control groups showed a significant difference in t (1–2) ( P-value &lt; .05). Conclusion: Vitamin D3 deficiency seems to increase OTM. Receiving oral supplements of vitamin D3 may not have much effect on increasing the level of vitamin D3. The lowest OTM rate was observed in the control group.

Investigating the Effectiveness of Low-Level Laser in Reducing Root Resorption of the Upper Incisors During Intrusion Movement Using Mini-Implants in Adult Patients With Deep Overbite: A Randomized Controlled Clinical Trial.

Deep bite is a common characteristic of malocclusion, and many methods are used to treat it, including mini-implants used for the intrusion of the upper incisors. Orthodontically induced inflammatory root resorption (OIIRR) is an inevitable and unexpected side effect of orthodontic therapy. However, resorption of the root could be affected by the type of tooth movement, such as intrusion. Several studies have indicated the effectiveness of low-level laser therapy (LLLT) in accelerating orthodontic movement, but studies that have evaluated the role of this laser in reducing the risk of OIIRR have been limited. This trial aimed to investigate the effectiveness of LLLT in reducing the resorption of the roots of the upper incisors during their intrusion in the context of deep bite correction. Thirty patients (13 males, 17 females; mean age 22.4±3.37 years) with deep overbite were recruited and allocated to the laser or the control groups. Mini-implants were inserted between the roots of the upper central incisors and the lateral incisors from the labial aspect at the gingival-mucosal junction on both sides with a force of 40 g on each side through an NiTi coil spring. A low-level laser (Ga-Al-As) with 808 nm wavelength in a continuous mode, with the parameters250 milliwattpower output, 4 Joules/point energy density, and 16 seconds irradiation per point, was applied to the root of each of the upper incisors. The laser was applied on the first day of the upper incisor intrusion (T1), then on days 3, 7, and 14 of the first month. In the second month, the laser was applied every 15 days, adjusting the spring strength every four weeks until the end of the intrusion stage (T2), which was determined by reaching a normal overbite. As for patients in the control group, the strength of the nickel-titanium springs was adjusted every four weeks to the required strength of 40 g on each end until reaching a normal overbite. There was a volumetric decrease in both groups' upper central and lateral incisors roots, and this decrease was statistically significant (P<0.001). However, the difference between the two groups was not statistically significant in each central and lateral incisor volume root (P=0.345 and 0.263 for U1 and U2, respectively). Also, both groups had a linear decrease in upper central and lateral incisors roots, which was statistically significant (P<0.001). At the same time, the difference between the two groups was not statistically significant in each central and lateral incisor root length (P=0.343 and 0.461for U1 and U2, respectively). The low-level laser irradiation using the current protocol did not significantly affect the amount of root resorption induced by incisor intrusion in the experimental group compared to the control group.

Finite Element Study to Evaluate the Stress Around Mini-implant during Canine Retraction using Continuous and Interrupted Orthodontic Forces

Abstract:&#x0D; Objectives: This work aimed to determine the stress distribution around a mini-implant during dynamic canine retraction utilizing continuous and intermittent orthodontic forces and a three-dimensional finite element model.&#x0D; Materials and Methods: Establishing a three-dimensional finite element model of canine retraction. The model incorporates a mini-implant, alveolar bone, maxillary teeth, a closed coil spring, and an elastic chain. They were described as being homogeneous, isotropic, and linear elastic. Continuous and interrupted forces were approximated by a NiTi coil spring and an elastic chain, respectively. To retract the canine, a simulated orthodontic force of 1.5N, 2N, and 2.5N were loaded. ANSYS evaluated the value of the stress distribution around the mini-implant, canine, and bone interface (workbench 19).&#x0D; Results indicated that there was no significant difference between the values of maximum stress around the miniscrew, canine, and bone under different orthodontic loads when a closed coil spring and an elastic chain were evaluated.

Spring Back the Lost Space: Fixed Space Regainer for E Space Loss- A Case Report

Maintenance of the E space is crucial to the normal development of dentition and early loss of second deciduous molars due to caries can compromise the same if not managed with a space maintainer. Fixed space regainers are being increasingly used to upright and distalisation of molars regaining the lost space and offering rapid results over their removable counterparts. Sectional orthodontics has been the focus of interceptive orthodontics in the recent past and the use of pre-adjusted edgewise appliances bonded to the erupted teeth and introduction of NiTi coil springs can help in rapid space regaining.

Evaluation of Stress Distribution of Maxillary Anterior Segment during en Masse Retraction Using Posterior Mini Screw: A Finite Element Study

The current study aimed to perceive and estimate the distribution of stress generated by the forces on the maxillary anterior teeth during orthodontic retraction using the bilateral mini screw implant. Finite element models were generated from the three-dimensional (3D) reconstruction of the maxillary arch via cone–beam computed tomography (CBCT). These models imitate the retraction of maxillary anterior teeth with the mini screw placed as the skeletal anchorage. The titanium mini screw of 1.3 mm × 8 mm dimension was placed at a height of 9 mm between the first molar and second premolar on both sides of the maxilla. A nickel titanium (NiTi) coil spring of 9 mm length was attached from the mini screw implant to the power arm which generated a force of 250 gm/side. Two different power arms were placed between the lateral incisor and canine at a height of 4 mm (group 1) and 8 mm (group 2), respectively. There were no significant differences observed when the stress values were compared to the left side and the right side in group 1 with a power arm of 4 mm. In group 2, the stresses around the lateral incisors were found to be on the higher side when compared with the central incisors and canines. The length of the power arm shows no significant difference in stress distribution pattern on the left and right sides except for stresses moving from the canine region to the lateral incisor region with the increase in power arm height.

Effect of micro-osteoperforations on the rate of orthodontic tooth movement and expression of biomarkers: a randomized controlled clinical trial.

ABSTRACTIntroduction: Micro-osteoperforation is a minimally invasive technique that has been used to accelerate orthodontic tooth movement and reduce treatment duration. However, literature presents conflicting reports about this technique. Objective: To evaluate the effectiveness of micro-osteoperforations on the rate of canine retraction and expression of biomarkers in gingival crevicular fluid (GCF). Methods: This was a randomized clinical trial with split-mouth study design. Thirty adult subjects with age above 18 years (20.32 ± 1.96) who required fixed orthodontic treatment and extraction of maxillary first premolars were enrolled and randomly allocated to either the experimental or control group. Randomization was performed by block randomization method, with a 1:1 allocation ratio. The experimental group received three micro-ostoperforations (MOPs) distal to maxillary canine, using the Lance pilot drill. The retraction of maxillary canine was performed with NiTi coil-spring (150g) in both experimental and control groups. The primary outcome was the evaluation of canine retraction rate, measured on study models from the baseline to 16 weeks of canine retraction. Secondary outcomes were the estimation of alkaline and acid phosphates activity in GCF at 0, 1, 2, 3, and 4 weeks. Results: There was a statistically significant difference in the rate of canine retraction only after the first 4 weeks. Subsequently there was no statistically significant difference from the eighth to the sixteenth weeks between MOPs and control group. There was a statistically significant difference in alkaline and acid phosphates activity in GCF between MOPs and control groups during the initial 4 weeks of canine retraction. Conclusion: Micro-ostoperforation increased the rate of tooth movement only for the first 4 weeks; thereafter, no effect was observed on the rate of canine retraction during 8, 12 and 16 weeks. A marked increase in biomarker activity in the first month was observed.

The MH-WIRE, a novel coil-springe wire system: A prototype design.

OBJACTIVE:The authors introduced a novel wire system aiming to achieve optimal goals of tooth movement without multiple wire changes or sophisticated wire bending.MATERIALS AND METHODS:The system was composed of a single wire for all phases of treatment. The archwire was composed of NiTi coil springs connecting delta-shaped segments of 0.018˝ × 0.025˝ Titanium Molybdenum Alloy (TMA) segments to fit the 0.018˝ × 0.025˝ bracket slot, or 0.022˝ × 0.028˝ TMA segments to fit the 0.022˝ × 0.028˝ bracket slot. The coil spring was closed and packed in design. The coil-spring loops were constructed with 3 mm lumen. The wires were designed in three sagittal forms and the system provided nine forms of archwires.RESULTS:The wire systems have been an important component of treatment since the development of orthodontic science. Over time, the philosophy has evolved from endorsing wire bending to straight-wire treatment and then to custom-made archwires.CONCLUSION:This wire system was designed to be used as a “single-wire for the case” across all stages of treatment to achieve the ideal goals without any biological damage.

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.

Effect of Methotrexate Injection on Orthodontic Tooth Movement: An Experimental Study on Rats.

Introduction Knowledge about the effects of medications, vitamins, and various supplements on orthodontic tooth movement (OTM) is imperative for orthodontists. This study aimed to assess the effect of methotrexate (MTX) injection on OTM in rats. Materials and Methods Twenty-eight male Wistar rats were randomized into four groups (n = 7). The first molar and central incisor were connected using a nickel-titanium (NiTi) coil spring with a 50 g load in each rat. The two experimental groups received 0.75 mg/kg and 1.5 mg/kg MTX, respectively, intraperitoneally for 21 days. The negative control group did not receive any injection and did not undergo orthodontic treatment. The positive control group underwent orthodontic treatment and received 0.9% saline (NaCl) injections for 21 days. All rats were sacrificed with chloroform inhalation after 21 days; their maxilla was resected, and the mean number of Howship's lacunae, blood vessels, osteoclasts, and resorption lacunae was counted. The reduction in bone volume (bone volume to total volume ratio (BV/TV)) at the site of the maxillary molar was quantified by microcomputed tomography (micro-CT). Results OTM, the number of osteoclasts, and the number of blood vessels significantly increased in rats treated with MTX (P < 0.05). However, the increase in the number of Howship's lacunae and resorption lacunae was not significant (P > 0.05). Lower BV/TV in the MTX groups was in agreement with the increased number of osteoclasts. Conclusion Injection of MTX can significantly increase OTM and decrease root resorption in rats.

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.

Rate of Canine Retraction and Anchorage Loss – In Smart Clip versus Conventional Brackets (An in-vivo study)

Background: To analyse the rate of maxillary canine retraction and anchorage loss in Smart Clip Self Ligating (SCSL) and Conventional (CV) brackets. Materials and Methods: Forty four subjects were selected for the study requiring sectional maxillary canine retraction in first premolar extraction space during orthodontic treatment. The self ligating bracket (Smart Clip, 3M Unitek) on maxillary canine was compared to CV bracket (APC Victory series) on the contralateral side in a random split-mouth study design. Sectional canine retraction was done with a NiTi coil spring (150 gms force, 9 mm) on 0.016 í— 0.022" slot stainless steel wire. Results: The mean rate of distal movement of maxillary canine for the conventional (CV) bracket per 28 days was 1.048 mm and 1.027 mm for smart clip self ligating bracket (SCSL). Anchorage loss in molar was 0.586 mm and 0.652 mm for CV and SCSL bracket respectively. Conclusion: The rate of canine retraction for conventional bracket was faster than self ligating bracket, but not statistically significant (p&gt;0.05). Comparatively, no major difference was found in terms of molar anchor loss between both bracket types. Therefore, this study indicates that conventional brackets are equally efficient as compared to self ligating brackets for segmental canine retraction mechanics.

Orthodontic space closure in sliding mechanics: a systematic review and meta-analysis.

The aim of this systematic review was to compare the different force delivery systems for orthodontic space closure by sliding mechanics. Multiple sources including Cochrane Central, Ovid Medline, Embase etc. were used to identify all relevant studies. Randomized controlled trials (RCT) of parallel-group and split-mouth designs were included. Orthodontic patients of any age treated with fixed orthodontic appliances and requiring space closure. Search result screening, data extraction and quality assessment were performed independently and in duplicate by 2 reviewers. The included studies were grouped into parallel-arm and split-mouth studies and subgroup analysis was then performed for the type of retraction subsets; en-masse and individual canine retraction. A traditional meta-analysis, and network meta-analysis (NMA) for direct and indirect comparisons for the rate of space closure were performed. Thirteen studies, six parallel-arm and seven split-mouth were included. The traditional meta-analysis comparing Nickel-titanium (NiTi) closed coil springs and elastomeric power chain for the rate of tooth movement showed statistically significant difference favouring NiTi springs (MD: 0.24; 95% CI, 0.03-0.45; I2 0%, P = 0.02) and the comparison between NiTi springs and active ligatures also showed statistically significant result favouring NiTi springs (MD: 0.53; 95% CI, 0.44-0.63; I2 0%, P ˂ 0.00001) for the rate of tooth movement. NMA for the rate of space closure showed fairly confident evidence for NiTi coil springs when compared with elastomeric chain and active ligatures. The NiTi coil spring ranked best between all methods of space closure. There is moderate quality evidence in favour of NiTi coil springs for the rate of space closure when compared with active ligature and low quality of evidence favouring NiTi springs when compared with elastomeric chain. The ranking from NMA showed NiTi coil springs to be the best method for space closure with 99% chance. An urgent need for standardization of study designs and the need for development of an agreed core outcome sets and core outcome instrument measurement sets is evident. PROSPERO CRD42020157811.

Preliminary Histological Evaluation of the Application of Ozone in the First Days of Orthodontic Force Induction in Animal Model.

Objectives The aim of the study was to histologically evaluate the effect of ozone therapy on orthodontic force induction in an animal model. Materials and Methods Twenty-four Wistar rats were divided into three groups ( n = 8). A NiTi coil spring was installed from the maxillary first molar to the maxillary central incisor. G1 was control and G2/G3 received 1 mL of ozonated gas at concentrations of 10 and 60 µg/mL, in the buccal mucosa above the first molar roots. The animals were euthanized 3 and 5 days after the procedure. Histological sections were obtained, longitudinally of the first molar’ long axis, in the mesiodistal direction. The number of osteoclasts, osteoblasts, blood vessels, polymorphonuclear and mononuclear cells, formation of osteoid tissue and hyaline areas, and root resorption were evaluated with light microscope, in tension and pressure sides. Intergroup comparisons were performed with Kruskal–Wallis, Dunn, and Chi-square tests. Results At 3-days pressure side, a greater number of osteoclasts was observed in ozone groups and greater number of blood vessels and polymorphonuclear cells were observed in G2. On the tension side, there was a significantly greater number of blood vessels, osteoblasts, and mononuclear cells in G2. At 5-days pressure side, there was a significantly greater number of osteoclasts in G2, blood vessels and osteoblasts in the ozone groups, and lesser number of polymorphonuclear cells in G3. Conclusion Ozone therapy increased the number of osteoclasts on the pressure side and osteoblasts on tension side, in 10 µg/mL concentration, demonstrating histological parameters favorable to bone remodeling. The 60 µg/mL ozone concentration accelerated the periodontal ligament reorganization process.

An Intermetallic NiTi-Based Shape Memory Coil Spring for Actuator Technologies

Amongst various intermetallic shape memory alloys (SMAs), nickel–titanium-based SMAs (NiTi) are known for their unique elastocaloric property. This widely used shape remembering material demonstrates excellent mechanical and electrical properties with superior corrosion resistance and super-long fatigue life. The straight-drawn wire form of NiTi has a maximum restorable strain limit of ~4%. However, a maximum linear strain of ~20% can be attained in its coil spring structure. Various material/mechanical engineers have widely exploited this superior mechanic characteristic and stress-triggered heating/cooling efficiency of NiTi to design smart engineering structures, especially in actuator technologies. This short technical note reflects the characteristics of the NiTi coil spring structure with its phase transformations and thermal transformation properties. The micro-actuators based on NiTi have been found to be possible, suggesting uses from biomedical to advanced high-tech applications. In recent years, the technical advancements in modular robotic systems involving NiTi-based SMAs have gained speculative commercial interest.

Comparison of Rate of Space Closure using Active Tie Back and NiTi Coil Spring in Angle's Class I Bi-Max Malocclusion Subjects following Piezocorticision

Comparison of Rate of Space Closure using Active Tie Back and NiTi Coil Spring in Angle's Class I Bi-Max Malocclusion Subjects following Piezocorticision