Retraction Phase Research Articles

Divergence in Time Apportionments of Tongue Protraction and Retraction Phases for Feeding Honey Bee Drones and Workers

Honey bees have three castes, drones, workers, and queens, that accomplish different tasks. In this research, we revealed the divergence in feeding behavior of drones and workers by experimental and theoretical techniques from the perspective of tongue kinematics. We observed the feeding cycles from living drones and workers of Apis mellifera ligustica and introduced a fluid transport model for computing the energy consumption during nectar feeding. We derived the theoretically-optimal time apportionment ratios (TARs) in the tongue protraction and retraction phases of drones and workers under the objective function of maximizing the efficiency of nectar uptake. By comparing the theoretically-optimal TARs with the real ones, we drew a conclusion that there is a dichotomy in nectar-feeding behavior between drones and workers. The actual TAR of drones is not consistent with the theoretically-optimal TAR while the actual TAR of workers is. This dichotomy may be caused by caste-related labor and environmental constraints.

Effectiveness of anchorage with temporary anchorage devices during anterior maxillary tooth retraction: A randomized clinical trial.

ObjectiveThis study evaluated the efficiency of anchorage provided by temporary anchorage devices (TADs) in maxillary bicuspid extraction cases during retraction of the anterior teeth using a fixed appliance.MethodsPatients aged 12 to 50 years with malocclusion for which bilateral first or second maxillary bicuspid extractions were indicated were included in the study and randomly allocated to the TAD or control groups. Retraction of the anterior teeth was achieved using skeletal anchorage in the TAD group and conventional dental anchorage in the control group. A computed tomography (CT) scan was performed after alignment of teeth, and a second CT scan was performed at the end of extraction space closure in both groups. A three-dimensional superimposition was performed to visualize and quantify the maxillary first molar movement during the retraction phase, which was the primary outcome, and the stability of TAD movement, which served as the secondary outcome.ResultsThirty-four patients (17 in each group) underwent the final analysis. The two groups showed a significant difference in the movement of the first maxillary molars, with less significant anchorage loss in the TAD group than that in the control group. In addition, TAD movement showed only a slight mesial movement on the labial side. On the palatal side, the mesial TAD movement was greater.ConclusionsIn comparison with conventional dental anchorage, TADs can be considered an efficient source of anchorage during retraction of maxillary anterior teeth. TADs remain stable when correctly placed in the bone during the anterior tooth retraction phase.

Evaluation and comparison of surface characteristics of commercially available TMA wires using scanning electron microscopy and optical profilometer.

The aim of this study was to evaluate and compare the surface characteristics of colored titanium molybdenum alloy archwires (purple-coated TMA and honey dew-coated TMA) and the regular titanium molybdenum alloy archwires. The experiment comprised three groups, Group I - regular TMA archwires, Group II - purple-coated TMA archwires, Group III - honey dew-coated TMA wires involving 21 samples each. The surface characteristics were assessed using scanning electron microscopy and optical profilometer. The results were statistically analyzed using analysis of variance wherein Group I regular TMA wires exhibited a root mean square value of 148.071 nm and a standard deviation of 9.0027 nm followed by group II (purple-coated TMA wires) which showed a root mean square value of 84.095 nm with a standard deviation of 2.6005 nm, while group III (honey dew-coated TMA wires) was found to have a root mean square value of 71.681 nm with a standard deviation of 1.4645 nm on subjecting to optical profilometry. The surface roughness is higher for regular TMA wire exhibiting superior characteristic of color-coated TMA wires, especially honey dew-coated TMA wires over the regular and purple-coated TMA wires. This property of the archwires details regarding its application in both sliding and frictionless mechanics in retraction phase of fixed orthodontic treatment.

Aquaporin 1 (AQP1) regulates plasma membrane bleb formation by facilitating bleb retraction phase in cancer cells

Aquaporin 1 (AQP1) regulates plasma membrane bleb formation by facilitating bleb retraction phase in cancer cells

Quasi-steady model of a pumping kite power system

The traction force of a kite can be used to drive a cyclic motion for extracting wind energy from the atmosphere. This paper presents a novel quasi-steady modelling framework for predicting the power generated over a full pumping cycle. The cycle is divided into traction, retraction and transition phases, each described by an individual set of analytic equations. The effect of gravity on the airborne system components is included in the framework. A trade-off is made between modelling accuracy and computation speed such that the model is specifically useful for system optimisation and scaling in economic feasibility studies. Simulation results are compared to experimental measurements of a 20 kW kite power system operated up to a tether length of 720 m. Simulation and experiment agree reasonably well, both for moderate and for strong wind conditions, indicating that the effect of gravity has to be taken into account for a predictive performance simulation.

How to dip nectar: optimal time apportionment in natural viscous fluid transport

The mouthparts of some animals are highly evolved fluid transporters. Most honeybees dip viscous nectar in a cyclic fashion by using protrusible tongues with active hairs that can erect rhythmically. The glossal hairs flatten when the tongue extends into the nectar, and then erect outwards like an umbrella to catch nectar while retracting. This paper examines the potential capability of honeybees in allocating the duration of the tongue protraction and retraction phases for the sake of energy saving. A physical model is established to analyze energy consumption induced by viscous drag, considering tongue kinematics and variation of the surface profile in different phases of tongue movements. The results indicate that the theoretically optimal time apportionment ratio at which the energy consumption is the minimum, is directly related to the square root of the tongue’s diameter ratio between the protraction and retraction phase. Through dipping observations, we validate that the duration for the protraction and retraction phases show high accordance with the theoretical prediction. These findings not only broaden the insights into honeybee’s foraging strategy but inspire the design of high-performance microfluidic pumps with dynamic surfaces to transport viscous fluid.

In-plane and out-of-plane rotational motion of individual chain molecules in steady shear flow of polymer melts and solutions

Recent nonequilibrium molecular dynamics (NEMD) simulations of mildly entangled C400H802 and moderately entangled C700H1402 linear polyethylene melts undergoing steady shear flow have revealed that several inconsistencies between theory and experiment could be rectified by consideration of the rotational motion of individual polymer chains that occurs at moderate to high flow strengths. In this study, we investigated the configurational dynamics of the individual molecular chains that allow these once-entangled, long-chain molecules to execute retraction/extension semi-periodic cycles in response to the imposed shear via NEMD simulations. Brownian dynamics simulations were also performed to extract dynamical and configurational information about the similar cycles of polymer chain behavior that occur in dilute solutions of macromolecular chain liquids dissolved in low molecular weight solvents. Results revealed that the configurational motions of the individual chains in both melt and solution were essentially the same and governed by a single timescale that scaled exponentially with the magnitude of the shear rate. This configurational motion contained both in-plane and out-of-plane components with respect to the flow-gradient plane, with the out-of-plane component playing a much larger role during the retraction phase of the cycle than during the extension phase. This was determined to be caused by the enhancement of the retraction motion by the out-of-plane entropic Brownian forces; however, these entropic forces were detrimental to the in-plane hydrodynamic diffusive forces during the extension phase of the cycle and were thus suppressed. Consequently, the configuration of a rotating chain was significantly more compact during the retraction stage than during the extension stage, wherein the latter phase most molecules were more preferentially distributed in the flow-gradient plane.

Velocity of orthodontic active space closure with and without photobiomodulation therapy: a single-center, cluster randomized clinical trial

The objective of this two-arm, parallel randomized clinical trial was to assess the effectiveness of low-level light therapy (photobiomodulation) using an intraoral light-emitting diode (LED) device with respect to accelerating premolar extraction space closure during en masse retraction. This trial was conducted between January 2013 and February 2014 at the European Univeristy College Department of Orthodontics. The study included 60 orthodontic patients (age range, 11.3–47.1 years; mean age, 20.4 years) with premolar extractions. Patients (n = 60) were randomized into the photobiomodulation (PBM) group (n = 30) or the control group (n = 30). Eligibility criteria included no active caries, good oral hygiene, and an extraction orthodontic treatment plan. Extraction spaces were closed using NiTi closed springs utilizing 150 g of force. Extraction spaces were measured on study models at the beginning of en masse retraction (T1) and at space closure completion (T2). All measurements were obtained by a single investigator who was blinded to the group allocation of study models. The primary outcome was the velocity of extraction space closure (mm/month) during the period of en masse retraction. Treatment allocation was implemented using randomization with 2 major blocks of 30 patients, by asking each patient to draw a sealed envelope (n = 60) indicating allocation to the PBM or control group. The allocation ratio was 1:1. The PBM group of patients (n = 30) was treated with intraoral infrared LED light therapy for 3 min per arch per day using OrthoPulse™ (Biolux Research®, Vancouver, Canada) producing a continuous 850-nm wavelength and a power density of 33 mW/cm2 per arch per day to achieve a total energy density of approximately 6 J/cm2 at the surface of the device during the en masse retraction phase; patients were required to maintain over 80% compliance with daily device use. Compliance was monitored by the device controller’s onboard computer. Sixty patients were randomized between the two groups. Fifteen patients dropped out during the study period, but were accounted for in the primary analysis as an intention to treat (ITT) analysis through multiple imputations. Mean age for the PBM and control groups were 20.7 and 22 years, respectively. Patients treated with PBM exhibited a statistically significant higher velocity of space closure by 0.22 mm/month (95% confidence interval [CI], 0.09–0.49; p < 0.01). The mean velocity of space closure in the PBM group was 1.08 mm/month (SD 0.54) compared with the control group’s 0.86 mm/month (SD 0.42). A secondary analysis was conducted on the 45 patients that reached the primary outcome and did not deviate from the study protocol (15 dropout patients removed), providing 123 extraction spaces for the analysis—23 patients from the PBM group and 22 patients from the control group. No serious harms due to treatments were encountered during the study period. The results of this study suggest that PBM therapy accelerated the rate of orthodontic space closure during en masse retraction. This trial and its protocol were not registered on a publicly accessible registry.

Numerical simulation of the hair formation –modeling of hair cycle

In the recent years, the fields of study of anti-aging, health and beauty, cosmetics, and hair diseases have attracted significant attention. In particular, human hair is considered to be an important aspect with regard to an attractive appearance. To this end, many workers have sought to understand the formation mechanism of the hair root. However, observing growth in the hair root is difficult, and a detailed mechanism of the process has not yet been elucidated. Hair repeats growth, retraction, and pause cycles (hair cycle) in a repetitive process. In the growth phase, hair is formed through processes of cell proliferation and differentiation (keratinization). During the retraction phase, hair growth stops, and during the resting period, hair fall occurs and new hair grows. This hair cycle is believed to affect the elongation rate, thickness, strength, and shape of hair. Therefore, in this study, we introduce a particle model as a new method to elucidate the unknown process of hair formation, and to model the hair formation process accompanying the proliferation and differentiation of the hair root cells in all three dimensions. In addition, to the growth period, the retraction and the resting periods are introduced to realize the hair cycle using this model.

Modeling, Identification, Estimation and Adaptation for the Control of Power-Generating Kites

Large-scale kites, flying high-force crosswind trajectories, have been proposed for wind power generation. A two phase operational cycle generates net positive power using a ground-based motor/generator. In the traction phase the kite flies a high-force trajectory while reeling out the generator-connected tethers. A low-force retraction phase reels in the tethers and returns the kite to the start of the cycle. Highly variable conditions and significant uncertainty in the dynamics pose challenges to autonomous, well-controlled flight. The control task is divided into trajectory generation and tracking components and the most uncertain parameters in the model are identified online. The control structure uses these parameters in a robust framework resulting in an experimentally verified adaptive control scheme.

Evaluation of kinetic friction between regular and colored titanium molybdenum alloy archwires.

The aim of this study was to evaluate the kinetic frictional properties of colored titanium molybdenum alloy (TMA) archwires (purple-coated TMA and honey dew-coated TMA) and the regular TMA archwires. The experiment comprised of three groups, Group I - Regular TMA archwires, Group II - Purple-coated TMA archwires, Group III - Honey dew-coated TMA wires involving 21 samples each that were evaluated for their frictional properties using Instron Universal Testing Machine. The results were subjected to statistical analysis using analysis of variance wherein Group I Regular TMA wires revealed mean kinetic frictional value of 8.236 N and a standard deviation of 0.4038 N, while Group II (purple-coated TMA wires) showed a mean value of 5.297 N, standard deviation of 0.3128 N and Group III (honey dew-coated TMA wires) showed a mean value of 4.206 N and a standard deviation of 0.5353 N. The kinetic frictional values are higher for regular TMA wire exhibiting superior characteristic of color-coated TMA. Wires exhibiting superior characteristics are color-coated TMA wires, especially honey dew-coated TMA wires over the regular and purple-coated TMA wires. These superior properties of newly introduced wires can be considered for its application in both details friction and frictionless mechanics in retraction phase of fixed orthodontic treatment.

Membrane Tension Orchestrates Rear Retraction in Matrix Directed Cell Migration

In development, wound healing and cancer metastasis vertebrate cells move through 3D interstitial matrix, responding to chemical and physical guidance cues. Protrusion at the cell front has been extensively studied, but the retraction phase of the migration cycle is not well understood. Here we show that fast moving cells guided by matrix cues establish positive feedback control of rear retraction by sensing membrane tension. We reveal a mechanism of rear retraction in 3D matrix and durotaxis controlled by caveolae, which form in response to low membrane tension at the cell rear. Caveolae activate RhoA signalling to control local F-actin organisation and contractility in this subcellular region and promote the translocation of the cell rear. A positive feedback loop between cytoskeletal signalling and membrane tension leads to rapid retraction to complete the migration cycle in fast moving cells, providing directional memory to drive persistent cell migration in complex matrices.

Deployment/retraction of the rotating Hub-Spoke Tethered Formation System

The Hub-Spoke Tethered Formation System (HS-TFS) is now a hot issue in many space applications, such as multi-point measurements, providing flexible frame for solar sail and other membrane or net structures. To achieve the valuable advantages, such as reduction of fuel consumption, promotion of the formation stability, the HS-TFS is usually in the rotating state. In addition, it is necessary to change the length of the tethers to obtain a variable coverage of the entire plane of the rotating HS-TFS in some applications, that is, the deployment and retraction problems of the rotating HS-TFS. However, the rotating motion will increase the complexity of the deployment and retraction of the rotating HS-TFS. In this paper, the deployment and retraction of a rotating HS-TFS is investigated. Firstly, a mathematical model is derived to describe the dynamics of the rotating HS-TFS. Then, the Gauss pseudospectral method is employed to solve the optimal deployment and retraction problems of the rotating HS-TFS. Finally, numerical simulations for deployment and retraction of the rotating HS-TFS are performed. Numerical simulation results reveal that it is necessary to apply active control on the deployment and retraction phases of the rotating HS-TFS, and after employing the optimal control (Gauss pseudospectral method), the HS-TFS can reach the desired configuration.

Mucogingival surgery for patients under orthodontic treatment

Gingival recession is one of the common mucogingival problems during the orthodontic treatment. The causes of the gingival recession are similar to gingival recession in patients with periodontal diseases. Accumulation of bacterial deposits around the natural teeth induces the gingival inflammation and gingival recession occurs in the teeth with the lack of the supporting bone. However, malpositioned teeth which are labially positioned teeth or rotated teeth are more risky for gingival recession. Once root is exposed to oral cavity due to gingival recession, the orthodontic tooth movement is compromised and esthetic problems appeared. In addition, excessive gingival recession over the mucogingival junction jeopardizes the oral hygiene control, which has a risk of further gingival recession and bone loss around the tooth. To cover exposed root or to prevent further gingival recession, mucogingival surgery with gingival graft is recommended for the patients under orthodontic treatment. This case report aimed to present the mucogingival treatments of gingival recession observed during orthodontic treatment. Case I had had initial slight gingival recession before the orthodontic treatment. However, during the retraction phases, the gingival recession progressed and the periodontal treatment was referred. In case II, miller Class III gingival recession was occurred after correction of rotation. Both cases were treated by coronally advanced flap with free gingival grafts and recovered to the level of adjacent teeth despite of complete root coverage was not achieved in Case II. After periodontal treatment, orthodontic treatment was successfully completed. In conclusion, mucogingival surgery during the orthodontic treatment is recommended for the successful orthodontic treatment as well as periodontal health.

Mechanics of Droplet Interface Bilayer “Unzipping” Defines the Bandwidth for the Mechanotransduction Response of Reconstituted MscL

Fully fluidic three‐phase droplet interface bilayers (DIBs) are convenient systems for studies of physiochemical properties of lipid‐stabilized interfaces as well as for reconstitution of biological molecules involved in ion transport, sensing, and energy conversion. Recently, it was reported that the low‐threshold mutant of the bacterial mechanosensitive channel MscL can be transiently activated in DIBs under harmonic mechanical stimulation. However, the experimentally determined range of oscillation frequencies generating sufficient tension for MscL gating is narrow (0.1–0.3 Hz). Here, physical parameters of the system that define tension in the interface bilayer under equilibrium and dynamic regimes and their variations during viscoelastic responses of droplets to compression and retraction, are analyzed. It is found that the rate of interfacial bilayer “unzipping” during the retraction phase limits the process of droplet area relaxation, thus preventing tensile expansion in the subsequent cycles. This article proposes temporally asymmetric stimulation protocols with variable ratio of compression to retraction phases (duty cycle), which allows the slow shape relaxation process and stimulates MscL much more efficiently. The new protocol activates a larger proportion of MscL's fully open states relative to the population of subconductive states over a wider range of frequencies.

Effects of diode laser (980nm) on orthodontic tooth movement and interleukin 6 levels in gingival crevicular fluid in female subjects.

The aim of this study was to evaluate the effects of low-level laser irradiation on the rate of orthodontic tooth movement (OTM) and the interleukin-6 (IL-6) concentration in gingival crevicular fluid (GCF) during orthodontic treatment. In this randomized split-mouth double blind clinical trial, 11 female patients aged 14 to 25years (mean 19 ± 4.21year), who required canine retraction following four first premolars extraction, were selected. The GaAlAs laser diode laser (A.R.C. Laser GmbH, Nürnberg, Germany) (980nm, 100mW, 5.6J/cm2, three points from the buccal side and three from lingual side of the tooth, 56s, running in continuous mode) was used for canine retraction in only one maxillary quadrant (LG). The irradiation time for each cervical and middle third of the tooth was 10s, and 8s for the apical third of the tooth. The other maxillary quadrant served as the control group (CG) using the laser pseudo-application in this side. The laser irradiation was applied on days 0, 7, 14, 21, and 28 of each month during the canine retraction phase. Canine retraction was done using closed coil spring with 150g force on rectangular wires after the alignment and leveling. This study was done in 11months. Dental casts were made at different time points during the treatment, and the amount of tooth movement was measured. To evaluate the levels of IL-6, GCF samples were collected from the distal side of the maxillary canine teeth on both quadrants at the beginning of the trial, the end of aligning phase, and on day 21 of each month during canine retraction. Although the mean rate of canine retraction was higher in the LG (0.013) than the CG (0.012) and there was definitely a tendency for more canine retraction in the LLLI, but the results failed to show any significant difference between the mean rate of canine retraction of both groups (P = 0.068). A paired t test showed that there was no significant difference in the mean concentration of IL-6 at various stages of the treatment between the groups during canine distalization (P > 0.05). Therefore, conclusive evidence could not be provided to support the efficacy of the diode laser (980nm) in accelerating OTM in female subject.

A Nonlinear Computational Model of Tethered Underwater Kites for Power Generation

The dynamic motion of tethered undersea kites (TUSK) is studied using numerical simulations. TUSK systems consist of a rigid winged-shaped kite moving in an ocean current. The kite is connected by tethers to a platform on the ocean surface or anchored to the seabed. Hydrodynamic forces generated by the kite are transmitted through the tethers to a generator on the platform to produce electricity. TUSK systems are being considered as an alternative to marine turbines since the kite can move at a high-speed, thereby increasing power production compared to conventional marine turbines. The two-dimensional Navier–Stokes equations are solved on a regular structured grid to resolve the ocean current flow, and a fictitious domain-immersed boundary method is used for the rigid kite. A projection method along with open multiprocessing (OpenMP) is employed to solve the flow equations. The reel-out and reel-in velocities of the two tethers are adjusted to control the kite angle of attack and the resultant hydrodynamic forces. A baseline simulation, where a high net power output was achieved during successive kite power and retraction phases, is examined in detail. The effects of different key design parameters in TUSK systems, such as the ratio of tether to current velocity, kite weight, current velocity, and the tether to kite chord length ratio, are then further studied. System power output, vorticity flow fields, tether tensions, and hydrodynamic coefficients for the kite are determined. The power output results are shown to be in good agreement with the established theoretical results for a kite moving in two dimensions.

Pinhole formation from liquid metal microdroplets impact on solid surfaces

The impact of molten metal droplets on solid substrates may entrap gas to form pinholes. This letter shows that the detailed pinhole structure is more sophisticated than expected: the void is toroid, which is a result of rapid contact line retraction and subsequent phase change. The substrate surface roughness affects the pinhole size by providing leaky channels that weaken gas pressure buildup. When the droplet diameter is sufficiently large, Kevin-Helmholtz instability may be triggered to form multiple pinholes.

The Morphology and Reciprocation Movement of Honeybee's Hairy Tongue for Nectar Uptake

A honeybee uses its brush-like tongue (glossa) to dip nectar and the setae densely distributed on it can increase the amount of trapped nectar observably. The glossa is often simplified as a cylinder covered by uniformly distributed and vertically erected setae during the drinking process, herein variations of the dimensions together with the erection angles of glossal setae are assumed to be negligible. In this paper, a dynamic model for the glossa retraction phase under the specific erection pattern of glossal setae is established, and the energy saving mechanism is extensively studied by comparing four types of erection patterns. Then the theoretically-optimal configuration, which satisfies the minimum energy consumption, is achieved from the dynamic model. Using the scanning electron microscope and a specially-designed high-speed camera system, we measure the dimensions of the glossal satae and capture dynamics of the hairy glossa in nectar feeding. It is proven that the erection angle of the glossal setae varies along the tongue axis, which shows a high concordance with our theoretically-optimal configuration. Compared with the hypothetical uniform distribution mode of glossal setae proposed by former researchers, we obtain a 16% increase in energy saving from actual erection pattern.

Non-surgical adjunctive interventions for accelerating tooth movement in patients undergoing fixed orthodontic treatment.

Accelerating the rate of tooth movement may help to reduce the duration of orthodontic treatment and associated unwanted effects including root resorption and enamel demineralisation. Several methods, including surgical and non-surgical adjuncts, have been advocated to accelerate the rate of tooth movement. Non-surgical techniques include low-intensity laser irradiation, resonance vibration, pulsed electromagnetic fields, electrical currents and pharmacological approaches. To assess the effect of non-surgical adjunctive interventions on the rate of orthodontic tooth movement and the overall duration of treatment. We searched the following databases on 25 November 2014: the Cochrane Oral Health Group's Trials Register (November 2014), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2014, Issue 10), MEDLINE via OVID (1946 to November 2014), EMBASE via OVID (1980 to November 2014), LILACS via BIREME (1980 to November 2014), metaRegister of Controlled Trials (November 2014), the US National Institutes of Health Trials Register (ClinicalTrials.gov; November 2014) and the WHO International Clinical Trials Registry Platform (November 2014). We checked the reference lists of all trials identified for further studies. There were no restrictions regarding language or date of publication in the searches of the electronic databases. We included randomised controlled trials (RCTs) of people receiving orthodontic treatment using fixed appliances along with non-surgical adjunctive interventions to accelerate tooth movement. We excluded non-parallel design studies (for example, split-mouth) as we regarded them as inappropriate for assessment of the effects of this type of intervention. Two review authors were responsible for study selection, risk of bias assessment and data extraction; they carried out these tasks independently. Any disagreements were resolved by discussion amongst the review team to reach consensus. The review authors contacted the corresponding authors of trials to obtain missing information and data to allow calculation of mean differences (MD), 95% confidence intervals (CI) or risk ratios (RR) when these were not reported. We included two studies in this review, which were both assessed as being at high risk of bias. The two studies, involving a total of 111 participants, compared the use of Tooth Masseuse and OrthoAccel with conventional treatment mechanics during orthodontic alignment and canine retraction phases, respectively. Both studies included objective assessment of the amount or rate of tooth movement, but we were not able to meta-analyse this data as they used different outcome measurements at different stages of the orthodontic treatment process. One study measured subjective evaluation of pain and discomfort and the other evaluated adverse effects. The studies did not directly report either the duration of orthodontic treatment or the number of visits during active treatment.Using the Tooth Masseuse with 111 Hz at 0.06 Newtons (N) for 20 minutes daily resulted in greater reduction in irregularity in the lower incisor region over 10 weeks, assessed using Little's Irregularity Index (LII) with a mean difference (MD) of 0.6 mm (95% confidence interval (CI) -0.94 to 2.34) when compared to the control group. Pain and discomfort increased at six to eight hours after arch wire placement and after seven days, with minimal difference between the intervention and control groups. No statistical tests were provided for either variable and the differences between the two groups were not clinically important.Using OrthoAccel with 30 Hz at 0.25 N for 20 minutes daily produced a higher rate of maxillary canine distalisation in comparison to the control group (MD 0.37 mm/month; 95% CI -0.07 to 0.81; P = 0.05). Whilst this difference suggested 50% faster tooth movement using the vibrational appliance, the absolute differences were marginal and deemed clinically unimportant. Similar levels of non-serious adverse effects were reported in the intervention and control groups with a risk ratio of 0.96 (95% CI 0.32 to 2.85).Overall, the quality of the evidence was very low and therefore we cannot rely on the findings. There is very little clinical research concerning the effectiveness of non-surgical interventions to accelerate orthodontic treatment. The available evidence is of very low quality and so it is not possible to determine if there is a positive effect of non-surgical adjunctive interventions to accelerate tooth movement. Although there have been claims that there may be a positive effect of light vibrational forces, results of the current studies do not reach either statistical or clinical significance. Further well-designed and rigorous RCTs with longer follow-up periods are required to determine whether non-surgical interventions may result in a clinically important reduction in the duration of orthodontic treatment, without any adverse effects.