Retainer Wire Research Articles

The effects of fulvic acids and low-level laser therapy on orthodontic retention in rats

BackgroundShortening retention time and minimizing relapse rates are ongoing challenges in orthodontics. This study investigated the effects of natural fulvic acids (FAs) and low-level laser therapy (LLLT) on orthodontic retention in rats.MethodsSeventy-two male Sprague-Dawley rats underwent mesial movement of the left maxillary first molar using a 50 g force via a nickel-titanium tension spring. After three weeks of movement, the rats entered the retention phase with retainer wires and were divided into four groups: Control (no intervention), FAs (80 mg/kg orally daily), LLLT (808 nm laser twice weekly), and FAs + LLLT (both treatments). Retainers were removed on days 7, 14, and 21 for a 3-day relapse assessment. Maxillary impressions were analyzed for relapse rates using 3Shape software, alongside histological and immunohistochemical evaluations of bone morphogenetic protein-2 (BMP-2) expression in periodontal tissues, with differences among groups analyzed using an ordinary two-way analysis of variance (ANOVA).ResultsThe relapse rate decreased over time, particularly at 10, 17, and 24 days (p < 0.001). The FAs group did not significantly affect relapse rates compared to the control group (p = 0.084). In contrast, both the LLLT and FAs + LLLT groups significantly reduced relapse rate (p < 0.001), with no significant difference between these groups (p = 0.555). Histological examination revealed active osteoclasts on day 10, decreasing by days 17 and 24. The LLLT and FAs + LLLT groups showed less local cementum resorption and better periodontal fiber arrangement. All treatment groups significantly increased BMP-2 expression (P < 0.05) compared to controls. with LLLT and FAs + LLLT differing significantly from FAs (P < 0.001), though no difference was observed between LLLT and FAs + LLLT (P = 0.578).ConclusionsFAs did not significantly reduce relapse rate with retainers, while LLLT effectively reduced relapse rates, showing no additional benefit from combining FAs with LLLT. Both FAs and LLLT increased BMP-2 expression in PDL fibroblasts but with no synergistic effect.

PEEK Retainers without CAD-CAM: Simple Solutions for Everyday Challenges

Background: The need to perform occasional or continuous MRI exams and the interference with metal orthodontic appliances might be important and take a primary role during retention since the retention period is significantly longer than orthodontic treatment. Several non-metallic materials were proposed as potential alternatives to perform fixed retainers in orthodontics, but they showed internal limits. Methods: Polyetheretherketone (PEEK) was used in the present clinical report as a fixed orthodontic retainer in the lower arch in order to perform an appliance with mechanical properties comparable to metallic ones but with a higher biocompatibility material and without the need for removal in case of an MRI exam. The retainer wire was handmade in the studio and then shaped to fit the arch. Results: PEEK showed a good capability for constructing a lingual fixed retainer compared to other aesthetic non-metallic and metallic materials. Conclusions: To the best of our knowledge, this study proposes how to easily build a retainer in PEEK and provides a clinical example of how this material can be beneficial.

Physico-Mechanical Properties and Bonding Performance of Graphene-Added Orthodontic Adhesives.

This study aimed to assess the key physico-mechanical properties and bonding performance of orthodontic adhesives with graphene addition for bonding a fixed retainer. Transbond LR (3M) and Transbond LV (3M) with no graphene were set as the control groups. Graphene was added into LR and LV at concentrations of 0.01 wt%, 0.05 wt% and 0.1 wt%. The stickiness of the uncured samples (n = 5) and real-time degree of conversion (DC) of the samples (n = 3) were measured over a 24-h period using Fourier-transform infrared spectroscopy. The hardness and other mechanical parameters, including the Martens hardness (HM), indentation modulus (EIT), elastic index (ηIT) and creep (CIT), were measured (n = 5). To measure the shear bond strength (SBS), adhesive composites were applied using a mold to bond the retainer wire to the lingual surfaces of bovine incisors (n = 10). Fracture modes subsequent to the SBS test were examined under light microscopy. Statistical analysis was conducted using ANOVA and Tukey tests (α = 0.05). In the LR groups, the LR + 0.01 showed the highest SBS (12.6 ± 2.0 MPa) and HM (539.4 ± 17.9 N/mm2), while the LV + 0.05 (7.7 ± 1.1 MPa) had the highest SBS and the LV + 0.1 had the highest HM (312.4 ± 17.8 N/mm2) among the LV groups. The most frequent failure mode observed was adhesive fracture followed by mixed fracture. No statistical difference was found between the graphene-added groups and the control groups in terms of the EIT, ηIT and CIT, except that the CIT was significantly lower in the LR + 0.01 than in the control group. Graphene addition had no significant adverse effect on the stickiness and DC of both LR and LV.

The Micromechanical Properties and Surface Roughness of Orthodontic Retainer Wires-An In Vitro Analysis.

Despite the large variety of retainer wires available, no studies could be found comparing the micromechanical properties and surface roughness of different retainer wires. Such characteristics affect the survival of the fixed retainer in terms of both fracture resistance and resistance to debonding from the tooth. Therefore, the aim of the present study was to examine and compare those characteristics in popular retainer wires. six different popular orthodontic retainer wires were subjected to instrumental indentation based on the Oliver and Pharr method. The geometric surface structure was analysed using a non-contact profilometer. stainless steel wires had a higher hardness and a higher elastic modulus compared to titanium wires and white gold chain. The titanium wire and the white gold chain showed much more roughness than other wires. stainless steel wires are the most resistant, considering both the shape retention capacity and the ability to resist abrasive wear. The titanium wire showed the lowest hardness and, thus, the highest susceptibility to deformation. Bond-a-braid, Retainium and Orthoflex white gold are more resistant to fracture than other steel wires. Titanium wire and chain retainer wires have more roughness, which is a great advantage in terms of mechanical adhesion to composite materials.

Innovative and simple technique of stabilizing the lingual retainer wire before bonding

Long-term stability of orthodontic treatment outcome is attained through retention. Fabrication and bonding of the lingually bonded retainer on the lingual tooth surface are a technique-sensitive and time-consuming procedure. Stabilizing the lingual retainer wire on the tooth surface throughout the bonding procedure is a challenging task for the operator. This article introduces a new simplified technique of stabilizing the lingual retainer wire before bonding.

The dewdrop retainrer clip – for easy placement of fixed lingual retainers

In Orthodontics, retention period is the most important phase of orthodontic treatment. Malocclusions requiring permanent retention for stability often need fixed lingual bonded retainers for holding the teeth in position. It has several advantages such not being visible and requires no patient cooperation during the retention phase. This article presents a simpler and innovative method of stabilizing the lingual retainer wire during bonding procedure by just holding it with prefabricated Dewdrop retainer holding clip.

A Novel 3-Dimensional Printed Nanoceramic Hybrid Resin Fixed Lingual Retainer: Characterization and Mechanical Tests.

Introduction: An innovative retention protocol was developed to create a new 3D-printed fixed retainer employing SprintRay OnX nanoceramic hybrid resin. The feasibility and usability of the retainer were subsequently evaluated. Methods: Identification and characterization of SprintRay OnX was done using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray (SEM-EDX), field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and flexural strength. Load-deflection and pull-out tests were conducted on the 3D-printed straight wires, with three distinct cross-sectional geometries: round (1 mm), oval (1 mm × 1.5 mm) and semielliptical (1 mm × 1.5 mm). Twisted G&H and coaxial Respond stainless steel multistrand retainers were used for comparison. In the load-deflection test, a three-point bending test (3PBT) was employed. For the pull-out test, the retainer wire was inserted into the composite, which was placed in a centrally located hole of an acrylic block; the retainer wire was subjected to a tensile force along its long axis. Results: Characteristic bands close to those of PMMA were observed in the FTIR spectra. SEM-EDX and XRD revealed a crystalline material with homogeneously distributed Yb element signals (19.4%). On FE-SEM micrographs, small clumps were displayed on smooth surfaces. The flexural strength and the flexural modulus were, respectively, 142.48 MPa and 7.842 GPa. All groups of 3D-printed wires exhibited significantly higher load-deflection levels than the multistrand wires (MSWs). Concerning pull-out forces, they fell in between twisted G&H (96 N) and coaxial Respond (48.09 N) retainer wires. The 3D-printed wires fractured cohesively without detachment from the adhesive, suggesting that the chemical bond was adequate for satisfactory wire integration, yet the wire's strength was compromised. Concerning the cross-sectional geometry, the load-deflection and the pull-out forces of 3D-printed oval and semielliptical wires were significantly higher than that of 3D-printed round wires, which was attributed to the larger cross-sections of the wires. Conclusion: Oval and semielliptical 3D-printed wires offered favorable features as lingual retainers.

Elemental composition, corrosion resistance and mechanical properties of computer-aided design and computer-aided manufacturing fixed retainers versus conventional fixed retainers.

To investigate the elemental composition, corrosion resistance, and mechanical properties of computer-aided design and computer-aided manufacturing (CAD-CAM) retainers versus conventional fixed retainers (FRs). Eight different retainer wires were investigated. Energy dispersive X-ray spectroscopy was used to determine the elemental composition. Leakage was analysed according to ISO 10271:2020 guidelines. Hardness was tested using the Vickers method with a load of 0.3 kg. The tensile force and tensile strength were evaluated. Multiple comparisons among wires of hardness, tensile force, and strength were conducted using the Welch t-test, with Bonferroni correction. Nickel was present in all wires. The CAD-CAM-FR wire, which contained more nickel than the other wires, had no measurable leakage. The gold-plated wires had the highest total leakage, but did not exceed the ISO standard limit. The hardness of the stainless-steel twisted wires was the highest and that of the CAD-CAM-FR wire was the lowest. The tensile strength of the CAD-CAM-FR wire was significantly lower than that of the other wires and similar to the other twisted-wire retainers. The CAD-CAM-FR wire is likely to have high corrosion resistance and flexibility due to its low hardness.

Comparative Evaluation of Durability and Hygiene Between Multistrand Round Dead Soft and 8-Braid Flat Dead Soft Stainless Steel Retainer Wire

Aim and Objectives The present study aims at evaluation and comparison of durability and hygiene between 2 different lingual retainer wires bonded between premolar to premolar, that is, maxillary or mandibular arch in the same patient. Materials and Methods Eighty retainer wires were placed in 40 patients. They were assigned to 2 groups and subjected to 2 different types of retainer wires (multistrand round and 8-braid flat). Results The mean durability of multistrand round retainer wire (235.7 ± 67.28 days) was more than 8-braid flat retainer wire (153.5 ± 43.85 days) irrespective of arches to which they were bonded, which was statistically significant. Scores for plaque index, calculus index, and gingival index were found more with 8-braid flat retainers and in lower arch than multistrand round retainer and in upper arch but these are statistically not significant. Conclusion The mean durability of multistrand round retainer wire was more than 8-braid flat retainer wire. The analysis did not find any statistical significant association for deposition of plaque, calculus, and gingival inflammation between different retainer wires and between arches.

Assessment of the Impact of Adhesive and Wires Types on the Tensile Bond Strength of Fixed Lingual Retainers Used in Orthodontics: An In Vitro Study

Introduction: We aimed to assess the impact of adhesive and wires types on the tensile bond strength of fixed lingual retainers. Methods: A total of 160 intact bovine teeth were collected, cleaned, stored in 25% sodium hypochlorite, and randomly assigned to two groups based on the adhesive type: a two-step adhesive and a one-step adhesive. Each group was further divided into four subgroups based on the type of lingual retainer wire, which included (A) 8-strand braided stainless steel wire, (B) three-strand titanium retainer wire, (C) stainless steel chain, and (D) fiber-reinforced retainer. A tensile bond strength test was conducted using a universal testing machine at a controlled speed of 10 mm/min. Result: The 8-strand braided stainless steel wire and stainless steel chain bonded by one-step self-priming adhesive showed significantly higher tensile bond strength (P &lt; 0.001). The adhesive wire significantly affected the tensile bond strength (P &lt; 0.001). Conclusion: Within the limitations of this in vitro study, it can be concluded that stainless steel wire and chain bonded by one-step self-priming adhesive showed higher tensile bond strength.

Importance of Early Detection of Wire Syndrome: A Case Series Illustrating the Main Stages of the Clinical Gradient.

(1) Context and Objective: Wire syndrome (WS) refers to dental displacements which can be qualified as aberrant, unexpected, unexplained, or excessive of teeth still contained by an intact orthodontic retainer wire without detachment or fracture, leading to evolving aesthetic and/or functional consequences, both dental and periodontal. The clinical diagnosis of WS in severe cases is often easy. On the other hand, emerging cases must be detected early to stop this evolutionary process as soon as possible, as well as to effectively manage unwanted dental displacements and associated dento-periodontal tissue repercussions. The aim of this retrospective study was to understand the challenges and importance of early diagnosis, highlight the clinical gradient of WS, and clarify the key elements of diagnosis for many practitioners confronted with this type of problem. (2) Materials and Methods: Three cases of increasing complexity were described: the history of wire syndrome, a description of the key elements of its diagnosis, and the final diagnosis itself. (3) Results: Different types and locations of wire syndrome have been observed, from early form to terminal wire syndrome. The three main stages of the clinical gradient are described as follows. In the first case, wire syndrome starting on tooth 41, called the "X-effect" type, was suspected. X-effect wire syndrome on 21, X-effect wire syndrome on 41, and Twist-effect wire syndrome on 33 were diagnosed in the second case, which can be classified as an intermediate case. In the extreme clinical situation of the last case, severe and terminal wire syndrome on tooth 41, the X-effect type, was observed. (4) Conclusions: This case series presents the main stages of the clinical gradient of WS. Although in the case of early WS it is very difficult to identify and/or differentiate it from movements related to a classical relapse phenomenon, the diagnosis of terminal WS is very easy. The challenge for the practitioner is therefore to detect WS as early as possible to stop the iatrogenic process and propose a personalized treatment depending on the severity of clinical signs. The earlier WS is detected, the less invasive the treatment.

A comparative evaluation of mechanical wear of adhesives used for bonded retainers that underwent brushing for 1hour under 36mm of linear action, using computer-aided 3D scan-an in vitro study.

The aim of the present study was to comparatively evaluate the mechanical wear of adhesives used in bonded retainers. Eighty mandibular acrylic teeth were included in the study that were divided into 4 different groups based upon the composite used. Each acrylic tooth was bonded with a retainer wire and composite of their respective group (Heliosit, Restofill, Tetric-N-flow, and Filtek Z350 XT). These bonded acrylic teeth were subjected to 3D scan in order to evaluate the volume and surface area of the composite. The 3D scans were recorded using MEDIT 3D scanner. After evaluating, the samples were subjected to brushing with the aid of a custom-made brushing simulator using a toothbrush with soft bristles and toothpaste slurry. The samples were subjected to 1hr of brushing. These samples were again subjected to 3D scans to evaluate (post-test volume and surface area) and underwent statistical analysis. The results showed the Heliosit group exhibited the highest mean volume (1.76mm3) and surface area (4.81mm2) difference between the pre-test and post-test values whereas the least mean volume difference (1.10mm3) and surface area difference (3.21mm2) were seen in the Tetric-N-flow group. All the four composites underwent change in the mean surface area and volume after being subjected to brushing, suggesting that the composites routinely used for bonding fixed bonded lingual retainers are subjected to changes due to abrasion. The Heliosit group, which showed least filler loading among the 4 composites, exhibited least resistance to wear, whereas the Tetric-N-flow group which had highest filler loading among the composites exhibited highest resistance to wear. The most crucial phase during orthodontic treatment is the retention phase. This phase is responsible for the long-term results of the treatment. The retainers that are placed in the oral cavity are subjected to changes due to oral environment, chemical changes, and mechanical changes. These changes have a direct effect on the retainers, which tend to alter their properties. Thus, the effects of these changes are to be studied thoroughly.

An assessment of the impact of adhesive coverage and wire type on fixed retainer failures and force propagation along two types of orthodontic retainer wires: an in vitro study.

To evaluate the force required to promote the failure of fixed orthodontic retainers with different adhesive (composite) coverage and to assess the presence and extent of force propagation with two different orthodontic retainer wires. Ortho-FlexTech and Ortho-Care Perform (0.0175 inches), each of 15-cm length, were bonded on acrylic blocks with different adhesive surface diameters (2 mm, 3 mm, 4 mm, and 5 mm). The samples (n = 160) were subjected to a tensile pull-out test, and debonding force was recorded. Fixed retainers using two different wires and 4-mm adhesive diameter were bonded on acrylic bases resembling a maxillary dental arch (n = 72). The retainers were loaded occluso-apically until the first sign of failure while being video recorded. Individual frames of the recordings were extracted and compared. A force propagation scoring index was developed to quantify the extent of force transmission under load. A 4-mm adhesive surface diameter required the highest debonding force for both retainer wires with significant differences compared with 2 mm (P < .001; 95% confidence interval [CI]: 8.69, 21.69) and 3 mm (P = .026; 95% CI: 0.60, 13.59). Force propagation scores were significantly higher for Ortho-Care Perform. Based on this laboratory-based assessment, consideration should be given to the fabrication of maxillary fixed retainers using a minimum of 4-mm diameter composite coverage on each tooth. Force appeared to propagate more readily with Ortho-Care Perform than with a flexible chain alternative. This may risk stress accumulation at the terminal ends with potential for causing associated unwanted tooth movement in the presence of intact fixed retainers.

Durability and Stability of Coaxial Wire and 3D-Printed Lingual Bonded Retainer: A Finite Element Study

Objective: To evaluate the durability and stability of Coaxial &amp; 3D (Three-dimensional) -printed bonded lingual mandibular retainer wire (3-3) at the middle third position with the application of forces. The objective is to evaluate the displacement of teeth, stiffness, and stresses on the wire. Methods: A comparison of coaxial wire (six-stranded stainless-steel wire) with 3D-Printed retainer wire (chrome cobalt alloy) was done by conducting a FEM (Finite Element Method) study for which mesh models were prepared onto which forces were applied. A load of 10N was applied to simulate biting forces and protrusive jaw movements during mastication. Results: There was a uniform displacement of teeth in the 3D-printed retainer wire whereas, in the case of coaxial retainer wire more force was noted onto the central incisor due to its low stiffness and thus inability to transfer force to an adjacent unit. High stiffness, von mises, and shear stresses were found to be present in the case of a 3D-printed retainer for which the high modulus of elasticity is responsible. The factor of safety for both materials was high but when compared to each other it was higher in the case of the 3D-printed retainer. Conclusion: 3D-Printed retainer wire showed higher durability and stability when compared to coaxial wire retainer, but requires clinical studies for better appraisal.

Evaluation of the Corrosion Resistance of Different Types of Orthodontic Fixed Retention Appliances: A Preliminary Laboratory Study

(i) Objective: The present study aimed to compare the electrochemical corrosion resistance of six different types of fixed lingual retainer wires used as fixed retention appliances in an in vitro study. (ii) Methods: In the study, two different Ringer solutions, with pH 7 and pH 3.5, were used. Six groups were formed with five retainer wires in each group. In addition, 3-braided stainless steel, 6-braided stainless steel, Titanium Grade 1, Titanium Grade 5, Gold, and Dead Soft retainer wires were used. The corrosion current density (icorr), corrosion rate (CR), and polarization resistance (Rp) were determined from the Tafel polarization curves. (iii) Results: The corrosion current density of the Gold retainer group was statistically higher than the other retainer groups in both solutions (p < 0.05). The corrosion rate of the Dead Soft retainer group was statistically higher than the other retainer groups in both solutions (p < 0.05). The polarization resistance of the Titanium Grade 5 retainer group was statistically higher than the other retainer groups in both solutions (p < 0.05). As a result of Scanning Electron Microscope (SEM) images, pitting corrosion was not observed in the Titanium Grade 1, Titanium Grade 5 and Gold retainer groups, while pitting corrosion was observed in the other groups. (iv) Conclusion: From a corrosion perspective, although the study needs to be evaluated in vivo, the Titanium Grade 5 retainer group included is in this in vitro study may be more suitable for clinical use due to its high electrochemical corrosion resistance and the lack of pitting corrosion observed in the SEM images.

Comparative evaluation of salivary microbial levels of red complex bacteria in patients wearing three different types of fixed lingual retainers: a clinical study

Introduction: One of the major challenges for orthodontists is the long-term stability of orthodontic treatment. This has urged orthodontists to seek methods to ensure stable results following the completion of orthodontic treatment. Incisor crowding is reported to occur in follow-up stages of orthodontically treated patients. Maintenance of incisor alignment following orthodontic treatment has led to the development of retainers (removable and fixed). Fixed lingual retainers have been criticized for their potential to compromise the periodontal status, due to accumulation of plaque and calculus along the retainer wire. Objectives: The aim of this study was to evaluate and compare salivary microbial levels of the “Red Complex Bacteria” after orthodontic treatment with fixed appliances, during the retention period using three different types of fixed lingual retainer wires. Materials and methods: 30 patients who have completed orthodontic treatment and met the inclusion criteria were randomly divided into 3 groups with 10 patients each. Fixed lingual retainers (Retainium or Penta-One or Bond-a-Braid wire) were bonded to the lingual surfaces of the six anterior teeth. Saliva samples were collected at debonding (T0), 4 weeks after debonding (T1) and 8 weeks after debonding (T2). Saliva samples were stored at -80o Celsius followed by PCR testing, One- way ANOVA test followed by Tukey's post hoc Test was used to compare the mean PCR values of P. gingivalis, T. denticola and T. forsythia (Red Complex Bacteria) between 3 groups at different time intervals. Repeated measures of ANOVA test followed by Bonferroni's post hoc Test was used to compare the mean PCR values of various microorganisms between different time intervals in each group. Results: The PCR test results demonstrated that the highest Red Complex Bacterial growth was observed in Group 3 (Bond-a-Braid wire) followed by Group 2 (Penta-One wire). Whereas the least Red Complex Bacterial growth was observed in Group 1 (Retainium wire) at different time intervals (T0, T1, T2). The maximum growth of P. gingivalis was observed at debonding (T0). The least growth of P. gingivalis was seen at 8 weeks after debonding (T2). Similarly, T. denticola and T. forsythia showed highest values at debonding (T0), while lowest values were observed at 8 weeks after debonding (T2). Conclusion: The present study concluded that there is statistically significant difference (p&lt;0.001) in the salivary microbial levels (Red Complex Bacteria) with different types of fixed lingual retainer wires at three time intervals (T0, T1 and T2).

Is there a difference among different bonded retainers in regard to survival rate?

Design A retrospective study.Cohort selection Inclusion criteria included: participants of any age who had completed their fixed orthodontic treatment on both arches and were treated by the same orthodontist in their private practice; had bonded retainers for five years, which were placed immediately after the orthodontic treatment in both arches; had one of three types of bonded retainers (0.026 × 0.010 inch Bond-A-Braid, 0.038 × 0.016 inch Ortho-FlexTech and Reliance Retainium Superior Brand Lingual Retainer Wire); had a final overbite of 2-4 mm after the completion of orthodontic treatment. Subjects who got their retainers changed, repaired or removed before five years, and syndromic patients, were excluded from the study.Data analysis The participants who agreed to contribute to the study and came for the final clinical examination were assessed for the retention status and the periodontal/gingival indies. Retention and retainer status: unwanted tooth movements and time and type of retainer failure. Periodontal/gingival indies: maximum pocket depth (PD) from the lingual side for the retained teeth and bleeding on probing (BOP). The authors performed a series of analyses to compare the orthodontic retainers regarding several outcomes and demographic variables. Briefly, the authors compared the orthodontic retainers concerning: i) age and treatment duration using analysis of variance (since the data were found to be normally distributed based on the Kolmogorov-Smirnov test); ii) demographic variables and BOP using several Chi-square tests; iii) PD via the Kruskal-Wallis test; and iv) survival rate through a Cox regression model alongside log-rank test.Results In total, 118 patients were included in this study, of which, 90 were women and 28 were men, with an average age of 22.34 ± 6.44 years. There was no statistically significant difference in the survival rate between the three types of retainers or between men and women. Likewise, there was no statistically significant difference in survival rate between the different age groups for the maxilla and mandible. Different maximum and minimum failure rates were observed between teeth in the maxilla and the mandible in the three retainers' group.Conclusions No difference was found between the three types of bonded retainers in regard to the survival rate and periodontal indices.

Which orthodontic retention protocol should I implement? A critical assessment of a randomised controlled trial.

Trial design A single-centre two-arm parallel group randomised controlled trial.Objectives To assess differences in dental stability, patient perceptions and compliance and retainer failures in adolescents treated with vacuum-formed retainers (VFR) compared with those receiving bonded canine-to canine retainers after five years in retention.Methods In total, 104 eligible adolescents treated with fixed appliances in both jaws in a Swedish orthodontic clinic were randomised to two retention protocols. The intervention protocol consisted of a VFR covering all erupted teeth in the maxilla and a VFR in the mandible covering first premolar to first premolar. The controls received a VFR in the maxilla covering all erupted teeth and a bonded retainer wire to the lingual surfaces of the canines. The primary outcomes were various dental stability measures assessed at: debond (T1); six months (T2); 18 months (T3); and after five years (T4) in retention. Generalised estimating equations were used to quantify the effect of the different interventions on these outcome measures. One operator assessed all outcomes and participants could not be blinded. For the secondary outcomes, the perception and compliance with the retention protocols were assessed and the prevalence and rationale of retainer failure at T4. The trial was registered at ClinicalTrials.gov (NCT03070444) and the research project was supported by the Centre for Research and Development, Region Gävleborg, Sweden.Results Of the 104 randomised patients, 30 were not available at T4, leaving 35 patients in the intervention and 39 in the comparator group. An intention-to-treat analysis was used to impute outcomes for the missing patients. Post-treatment changes at T4 were small in both jaws. In the maxilla, the Little's Irregularity Index (LII) increased similar in both retention groups (median difference: 0.3 mm). In the mandible, the median difference for the LLI in the bonded retainer group was 0.1 mm compared with 0.6 mm in VFR group. In both retention protocols, the overjet remained stable, the overbite increased and the arch lengths continued to decrease. Intercanine and intermolar width remained stable in the mandible. Intermolar width decreased significantly in the maxilla. No differences in satisfaction were found between retention protocols after five years. Also, 72% of patients had stopped or rarely wore the VFR appliances at T4. Besides some retainer failures in both groups, no serious adverse effects associated with the retainers were reported.Conclusions Most post-treatment changes in both retention protocols were small in both jaws, except for the anterior alignment in the mandible, which was more stable in the bonded retainer group. This difference is possibly not related to the retention technique but to the poor compliance with the VFRs and the inclusion of adolescents only. Satisfaction with both protocols was similar.

Inadvertent side effects of fixed lingual retainers : An in vitro study.

To better understand the side effects of fixed lingual retainers by means of an in vitro study in atwo-tooth model determining the three-dimensional (3D) force-moment components acting at adjacent teeth combined with different composite-wire interfaces. Triple-stranded round retainer wires were embedded in cured disks of flowable composite. At one side the composite-wire interface was untreated and checked to be absolutely fix. At the other side the composite-wire interface was configured as either an isolated compound with (1)petroleum jelly coating, or an adhered compound with (2)no manipulation, (3)ethanol degreasing or (4)ethanol degreasing and rectangular bending of the wire ends. The 3D force-moment components were registered, while the intertooth distance was increased in steps of 0.01 mm leading to increasing tension of the wire. Measurements were repeated after artificially aging the specimens. Retainer wire specimens with adhered compound (2, 3, 4) showed negative vestibulo-oral moments ranging maximally each between -0.3 and -0.9 Nmm in opposite direction to positive moments of 1.9 Nmm for specimens with isolated compound1. Significant tipping moments occurred in the group with isolated compound at lower forces than in those groups with adhered compound. Similar effects were observed after artificial aging. Side effects emerge under specific circumstances: an altered adhesive compound combined with the presence of oral forces. Compounds with lost adhesion at the composite-wire interface showed rotational moments in the direction of the wire windings even during low tensile forces similar to those that may occur in clinical settings. Opposite rotational moments leading to unwinding of the wire may occur in cases with adhered compounds at higher tensile forces. Utilization of round triple-stranded retainer wires without bent ends are of higher risk to induce inadvertent side effects.

Comparison of microleakage and shear bond strength of ribbon and twisted wire retainers bonded on human mandibular incisors with two different types of adhesives with and without primer: An in-vitro study

Background and objectivesShear bond strength and microleakage are the success factors of fixed retainers. Recently, primer-free composites were introduced to reduce chair time. The main objectives of this study were to compare the shear bond strength (SBS) and microleakage of GC Ortho ConnectTM Flow (OF) and TransbondTM XT (TXT) with two types of common retainer wires (0.0175-inch twisted wire and 0.028×.0.008-inch ribbon dead soft wire retainers). The secondary objectives of the study were to compare enamel-adhesive interface and wire-adhesive interface microleakages. Materials and methodsThis in vitro study was conducted on 132 human mandibular incisors (96 for bond strength and 36 for microleakage). The teeth were randomly divided into four groups for use of ribbon and twisted wires with OF and TXT adhesives. The bond strength was measured by a universal testing machine. Microleakage was evaluated by the dye penetration test using 0.05% fuchsine. Data were analysed by two-way ANOVA (alpha=0.05). ResultsNo significant difference was noted in bond strength among the four groups (P>0.05). However, the microleakage of OF was significantly higher than that of TXT at both the enamel-adhesive and wire-adhesive interfaces (P<0.001). The microleakage at the wire-adhesive and enamel-adhesive interface was not significantly different in groups 1 and 4 and was significant in group 2 and 3. ConclusionType of adhesive significantly affected the microleakage, and OF resulted in higher microleakage than TXT at both the enamel-adhesive and wire-adhesive interfaces. Type of wire had no significant effect on microleakage. Although OF showed comparable SBS to TXT, its higher microleakage may compromise its successful long-term clinical service.