Multistranded Stainless Steel Wires Research Articles

Stability and failure rate during 3 years of fixed retention: A follow-up of an randomized clinical trial on adolescents with four different lingual retainers.

To evaluate stability outcomes and failure rates associated with four types of lingual retainers: (1) dead-soft wire, (2) multistrand stainless steel (SS) wire, (3) CAD/CAM nitinol, and (4) connected bonding pads (CBPs) after 3 years of retention. This study enrolled 96 patients (66 females, 30 males) with a median age of 19 years with four types of lingual retainers: (1) 0.016 × 0.022-inch dead-soft wire, (2) 0.0215-inch five-strand SS wire, (3) 0.014 × 0.014-inch CAD/CAM nitinol wire, and (4) CBPs. The irregularity index, intercanine distances, and arch lengths were obtained and used to evaluate mandibular stability. Failure rates were also assessed during this study. Data were statistically analysed. Irregularity increased, whereas intercanine width and arch length decreased after 3 years of retention. The greatest irregularity was associated with the CBPs and the least with the CAD/CAM retainers. Changes in stability measurements were significantly higher in the dead-soft wire and CBPs than those in the CAD/CAM nitinol and multistrand SS wires. Parallel to these changes, the frequency of failure yielded similar results with the same significance between the groups. The failure rate of CBPs, in contrast to the CAD/CAM nitinol and multistrand SS wires, was significantly higher in the right quadrant (P < .05). After taking the 3-year results into consideration, CAD/CAM nitinol and multistrand SS wires were found to be more successful than the others in maintaining mandibular stability. The most failures were observed with CBPs after 3 years of retention.

Efficacy of CAD/CAM Technology in Interventions Implemented in Orthodontics: A Scoping Review of Clinical Trials.

Objectives To evaluate the efficacy of computer-aided design/computer-aided manufacturing (CAD/CAM) technology in interventions implemented in orthodontics. Methods A scoping review of scientific evidence was accomplished, involving different databases. MesH terms and keywords were provided to examine clinical trials (CTs) in all languages. Exclusively CTs that fulfilled the eligibility criteria were admitted. Results Eight CTs were chosen. These experiments evaluated 542 patients. Four CTs compared the computer-aided indirect bonding method versus the traditional direct bonding of orthodontic brackets. Three CTs compared CAD/CAM retainers with other types of retainers, and one CT compared the CAD/CAM group with multistranded stainless steel wires versus stainless steel wires. Regarding the efficacy of the interventions with CAD/CAM technology used in orthodontics, variable results were found. The indirect bonded customized CAD/CAM brackets presented just a slight effect on the treatment efficacy and therapy results. Two CTs showed that an indirect bonding self-ligating standard system had a similar quality of therapy in comparison with the CAD/CAM customized bracket system. Concerning the clinical failure rate, no differences were presented between the CAD/CAM retainer and other retainers. A CAD/CAM system had more loose brackets than a noncustomized system and was observed also a greater amount of immediate debonding with CAD/CAM indirect bonding than with direct bonding. CAD/CAM fixed retainers revealed inferior relapse and fewer failures than lab-based and conventional chairside retainers. No changes between treatment groups were observed regarding the total therapy time, amount of appointments, and quantity of archwire bends. Conclusions In general terms, no greater efficacy of CAD/CAM technology was observed over traditional therapies used in orthodontics. However, it was found that gingival inflammation and the accumulation of bacterial plaque and dental calculus were lower when CAD/CAM retainers were used. When comparing interventions that include CAD/CAM systems with conventional therapies, no significant reduction in care times was found.

Comparative assessment of relapse and failure between CAD/CAM stainless steel and standard stainless steel fixed retainers in orthodontic retention patients.

To compare relapse and failure rates of computer-aided design/computer-aided manufacturing (CAD/CAM) and standard fixed retainers. This single-center, single-blinded, prospective randomized clinical trial included 46 patients who completed active orthodontic treatment and complied with retention visits. The patients were randomly assigned to three groups: CAD/CAM group with multistranded stainless steel wires (CAD/CAM, n = 16), Lab group with the same multistranded wires (lab, n = 16), and control group with stainless steel Ortho-FlexTech wires (traditional, n = 14). Intraoral scans were obtained at placement of fixed retainers (T1), 3-month visit (T2), and 6-month visit (T3) and measured for intercanine width and Little's Irregularity Index. Failures were recorded. The CAD/CAM group experienced less intercanine width decrease than the traditional group at 3 months (mean difference, 0.83 ± 0.16 mm; 95% confidence interval [CI], 0.44-1.22; P < .001) and 6 months (mean difference, 1.23 ± 0.40 mm; 95% CI, 0.19-2.27; P < .05). The CAD/CAM group experienced less increase in Little's Irregularity Index compared with the lab group within 3 months (mean difference, 0.81 ± 0.27 mm; 95% CI, 0.12-1.49; P < .05). Failures from greatest to least were experienced by the lab group (43.8%), the CAD/CAM group (25%), and the traditional group (14.3%). Within 6 months of bonding fixed retainers, CAD/CAM fixed retainers showed less relapse than lab-based and traditional chairside retainers and less failures than lab-based retainers.

Advances in orthodontic archwires

Recent advances in orthodontic wire alloys have resulted in a varied array of wires that exhibit a wide spectrum of properties. Up until the 1930s, the only orthodontic wires available were made of gold. Subsequently, stainless steel was introduced and due to its superior properties gained popularity over gold. The introduction of nickel-titanium archwires revolutionized the orthodontic field with their shape memory &amp; superelasticity. Several other alloys with desirable properties have been adopted in orthodontics. These include cobalt-chromium, beta titanium and multi-stranded stainless steel wires. The availability of archwires with widely diverging properties has profound implications on appliance mechanics and can be used to advantage at different stages of orthodontic treatment. The newer archwires score over conventional wires in terms of efficiency, total treatment time, and finishing. Also, the current emphasis on esthetic treatment options in orthodontics has led to the development of esthetic archwires. Presently the orthodontist may select, from all the available wire types, one that best meets the demands of a particular clinical situation. The selection of an appropriate wire size and alloy type in turn would provide the benefit of optimum and predictable treatment results.

Evaluation of Mandibular Arch Width Changes following Fixed Retention in Post Orthodontic Patients - a Randomized Clinical Trial

Background: Retention is an integral phase in which teeth are maintained in their newly adapted position for which retainers are inserted. Retainers are generally of two types: removable and fixed. Fixed retainers are indicated in the mandibular arch for an indefinite period specifically in the non-extraction cases. Changes in intercanine and intermolar widths are valuable parameters to evaluate the stability. The objectives of this study were to assess and compare the mandibular intercanine and intermolar width changes following orthodontic treatment after insertion of two types of fixed lingual retainers for one year. Methods: Total 54 subjects were recruited in which two types of fixed lingual retainers were inserted in the mandibular arch randomly. Intercanine and intermolar arch widths were measured by digital caliper of 0.01 mm accuracy. Data was analyzed by using Statistical Package of Social Sciences (SPSS V-21). Chi-square and independent t tests were used to compare baseline characteristics. Intercanine and intermolar widths were assessed and compared using independent t test, p-value ≤ 0.05 is considered as statistically significant. Results: Intercanine width increased from baseline to T4 in both retainers. When mean differences of intercanine width were compared between two retainers significant differences were observed at T1, T2, T3 and T4 with significant p-values (&lt; 0.05) and increased intercanine width with multistranded stainless steel wire (MSW) retainers. Conclusion: Mandibular intercanine width increases significantly in post retention phase with multistranded stainless steel retainers. Thus, fiber reinforced composite retainers are more effective in preserving the arch width changes.

\u201cClinical comparison of bond failure rate between two types of mandibular canine-canine bonded orthodontic retainers- a randomized clinical trial\u201d

BackgroundBonded retainers are widely used as they are esthetically pleasing, easily acceptable, provide greater stability, compliance free and causes no soft tissue irritation and speech problems. Though, fracture and bond failure are their shortcomings. Therefore, the objectives of this study were to evaluate the number of bond failures and type of failure pattern between two types of mandibular canine-canine bonded retainers.MethodsTotal 60 subjects were recruited initially and were assessed for eligibility, out of which 6 were excluded and 2 were lost to follow up. They were randomly divided into two groups. Fiber reinforced composite (FRC) retainers were inserted in group 1 subjects while group 2 subjects received multistranded stainless steel (MSW) retainers. The subjects were recalled after every 3 months over a period of 1 year. Bond failure rate and failure pattern based on adhesive remnant index were evaluated at each visit. The bond failure rate and failure pattern were compared between the two retainers by using Chi-square test.ResultsThe bond failure rates were 42.94% for FRC retainer and 31.41% for MSW retainer. Hence, total number of bond failures in both retainers were 37.17%. The difference of bond failure between two groups was statistically significant (p = 0.012). Type “0” failure pattern was detected commonly with both types of retainers (p < 0.001).ConclusionOur findings indicate that multistranded stainless steel wire retainer is a superior option to be used for fixed lingual retention in mandibular arch as it exhibited lower bond failure as compared to fiber reinforced composite retainer. Adhesive failure is the most common type of bond failure observed with both types of fixed retainers.Trial registrationID NCT03881813 (https://clinicaltrials.gov/); March 19, 2019, retrospective registration.

What are the best materials to use for the first arch wire in orthodontic treatment?

Data sources Six electronic databases/registries including Medline, Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Oral Health's Trials Register, Embase, World Health Organization International Clinical Trials Registry Platform and The US National Institutes of Health Trials Registry (ClinicalTrials.gov) were searched up to October 2017. No restrictions of language or publication date were set.Study selection Only randomised controlled trials (RCTs) assessing the efficiency of initial arch wires to align teeth with fixed orthodontic braces in either or both upper and lower arches.Data extraction and synthesis Two reviewers abstracted data independently. Risk of bias was assessed using the Cochrane Collaboration Risk of Bias tool. Rate of alignment was considered the main outcome. Root resorption and pain level were considered adverse effects. Meta-analysis was performed when possible. Results Twelve RCTs involving 799 participants were included. Three studies were judged at high RoB, six were unclear and three were at low RoB. There was insufficient evidence to determine if there is a difference in the alignment rate between Multistrand stainless steel (MSS) and superelastic nickel-titanium (SNT) arch wires (mean difference (MD) -7.5 mm per month, 95% confidence interval (CI) -26.27 to 11.27; one study), between MSS and thermoplastic NiTi (TNT) arch wires, between conventional Niti (CNT) and TNT arch wires, between CNT and TNT arch wires and between SNT and TNT arch wires. In regards to pain level only two comparisons were assessed (MSS vs. SNT and SNT vs. TNT). The first one did not show meaningful differences while in the second insufficient evidence was identified. Conclusions In general terms there is insufficient evidence that any particular material is clinically superior to any other in regards to alignment rate, pain or root resorption.

Initial arch wires used in orthodontic treatment with fixed appliances.

Initial arch wires used in orthodontic treatment with fixed appliances.

The efficacy of orthodontic treatments for anterior crowding with Invisalign compared with fixed appliances using the Peer Assessment Rating Index.

The purpose of this retrospective study was to determine the efficacy of Invisalign in a large sample of patients compared to fixed appliances. The test group consisted of 100 patients treated with Invisalign compared with a control group treated with conventional fixed appliances matched for sex, age, and initial severity of malocclusion based on the amount of anterior dental crowding (Little Index) and the Peer Assessment Rating (PAR Index) scores. The retainer used was a 0.0175-inch multistranded stainless-steel wire bonded from canine-to-canine in the mandibular arch and from lateral inisor-to-lateral incisor in the maxillary arch. A paired t test was used to compare both initial and final PAR scores. There was an overall 80.9% improvement, and 63 subjects did not need any refinement. The mean number of aligners used was 14 (+ 15 for the refinements) in the maxillary arch and 29 (+ 14 for the refinements) in the mandibular arch. The mean duration of treatment was 14 months (+ 7 months for the refinements). Significant statistical differences were found in the posttreatment scores, within both the Invisalign group and the control group. No differences were found in the follow-up scores. Additionally, the duration of treatment was 4 months longer in the control group. More than 90% of the subjects treated with Invisalign achieved a significant improvement, as shown by the PAR scores. A need for additional aligners was reported for 37% of the patients. Fixed bonded retainers seem to be a good option in preventing tooth relapse after Invisalign and fixed conventional treatments.

A Systematic review on aligning efficiency of superelastic NITI: in comparison with conventional NITI and multistranded stainless steel archwires

Background: The initial leveling and aligning phase of orthodontic treatment involve the use of nickel titanium wires. The nickel titanium wires exhibit unique properties like shape memory and superelasticity. In the beginning, conventional nitinol wires were used, which lacked the superelastic property. Nowadays, superelastic nickel titanium wires are being used commonly. This systematic review aims to evaluate the efficiency of Superelastic NITi in the initial alignment of orthodontic treatment in comparison with conventional NiTi and multistranded stainless steel archwires by measuring the amount of decrowding and the time taken for decrowding.Method: A systematic literature search was performed on Pubmed, Cochrane, Google scholar &amp; Lilacs.Result: Thirty four studies were identified by the search and ten studies satisfied the inclusion criteria and one study was excluded after abstract reading. Finally nine articles were included for quality assessment.Conclusion: This systematic review concluded that there was no significant differences in the aligning efficiency of superelastic NiTi in comparison with conventional NiTi and multistranded stainless steel wires.Â

Forces in initial archwires during leveling and aligning: An in-vitro study.

Aim:This in-vitro study measured the force deflection behavior of selected initial alignment archwires by conducting three-point bending tests under controlled tests. The study tested three wire designs, namely, co-axial multistranded stainless steel wires, nickel–titanium, and copper–nickel–titanium archwires.Materials and Methods:The archwires were ligated to a specially designed metal jig, simulating the arch. A testing machine (Instron) recorded activation and deactivation forces of different deflections at 37°C. Forces on activation and deactivation were compared by one-way analysis of variance (ANOVA).Results:Significant differences (P < 0.05) in activation and deactivation forces were observed among the tested wires. The co-axial multistranded wire had the lowest mean activation and deactivation forces, whereas conventional nickel–titanium wires had more mean activation and deactivation forces at different deflections.Conclusion:The activation and deactivation forces were higher for nickel–titanium followed by copper–nickel titanium and co-axial wires. The amount of percentage force loss was more for co-axial wire, indicating that these wires are not ideal for initial leveling and aligning.

In vivo orthodontic retainer survival - a review.

BackgroundRelapse following orthodontic treatment is a constant concern of orthodontists. Fixed retention is preferred especially for the lower arch by most orthodontists.ObjectivesThis review focuses on in vivo studies. The main objective is to determine the survival rates of different types of retainer: glass-fiber reinforced composite resin, polyethylene or multistrand stainless steel wire bonded to each tooth from canine to canine in the mandibular arch. A second objective is to assess which of these types is less likely to cause additional problems and the third objective is to evaluate the factors that may influence retainer survival.Results and conclusionsThere were 8 studies identified that matched the objectives stated. Current in vivo studies on survival rate take little notice of the role of the material used for bonding of the fixed retainer. It is not possible to draw a conclusion on reliability of new types of retainers glass fiber reinforced composite resin or polyethylene compared to multistrand stainless steel wire. The multistrand wire remains the gold standard for fixed retention.Although it is a logical outcome that retainer survival is dependent on the application technique, there seems to be no research outcome proving that operator experience, moisture control are essential, nor does patient age or sex have statistically proven effects on survival rates.Adequate studies that involve such aspects should be performed.

Clinical evaluation of bond failures and survival between mandibular canine-to-canine retainers made of flexible spiral wire and fiber-reinforced composite.

Objectives: The purpose of this longitudinal prospective randomized study was to evaluate the clinical reliability of two different types of postorthodontic treatment retainers: a silanised-treated glass fibers-reinforced resin composite (FRC) and a directly bonded multistranded stainless steel wire. The hypothesis of the study was to assess if significant differences are present between failure rates of the two retainers. Study Design: This prospective study was based on an assessment of 87 patients (35 men and 52 women),with an average age of 24 years who required a lower arch fixed retainer after orthodontic treatment. Patients were divided in two groups. Assignment was carried out with random tables. A follow-up examination was carried out once a month. The number, cause, and date of single bond adhesive failures were recorded for both retainers over 12 months. Teeth that were rebonded after failure were not included in the success analysis. Statistical analysis was performed by means of a Fisher’s exact test, Kaplan-Meier survival estimates, and log rank test. Results: Bond failure rate was significantly higher (P=0.0392) for multistranded metallic wire than for FRC. Conclusions: Glass fiber-reinforced resin composite retainers and multistranded metallic wires showed no significant difference in single bond failure rates over a one-year follow up. Key words:Fiber reinforced composite, fixed retention, multistranded wire, orthodontics, retainer, splint.

A randomized clinical trial investigating pain associated with superelastic nickel–titanium and multistranded stainless steel archwires during the initial leveling and aligning phase of orthodontic treatment

Objective:To investigate and compare the effects of superelastic nickel–titanium and multistranded stainless steel archwires on pain during the initial phase of orthodontic treatment.Design:A double-blind two-arm parallel design stratified randomized clinical trial.Setting:A single centre in India between December 2010 and June 2012. A total of 96 participants (48 male and 48 females; 14.1±2.1 years old) were randomized (stratified on age, sex and initial crowding) to superelastic nickel–titanium or multistranded stainless steel archwire groups using a computer-generated allocation sequence.Methods:We compared 0.016-inch superelastic nickel–titanium and 0.0175-inch multistranded stainless steel wires in 0.022-inch slot (Roth prescription) preadjusted edgewise appliances. The follow-up period was 14 days. Outcome was assessed with a visual analogue scale at baseline and 32 pre-specified follow-up points. Data was analyzed using mixed-effects model analysis.Results:One participant was lost to follow up and 10 were excluded from the analysis due to bond failure or incomplete questionnaire answers. Ultimately, 85 participants (42 males and 43 females; 14.1±2.0 years old) were analysed for the final results. No statistically significant difference was found for overall pain [F value = 2.65, degrees of freedom (df) = 92.6; P = 0.1071]. However, compared to multistranded stainless steel wires, pain in subjects with superelastic nickel–titanium archwires was significantly greater at 12 h (t = 2.34; P = 0.0193), as well as at day 1 in the morning (t = 2.21, P = 0.0273), afternoon (t = 2.11, P = 0.0346) and at bedtime (t = 2.03, P = 0.042).Conclusion:For overall pain, there was no statistically significant difference between the two wires. However, subjects with superelastic nickel–titanium archwires had a significantly higher pain at peak level.

Is nickel titanium superior to multistranded stainless steel wire in aligning crowded lower anteriors? A comparative in-vivo study.

Introduction: One of the most perplexing phenomenons in orthodontics is the crowding of anterior teeth, which brings the patient to the orthodontist seeking remedy because of its aesthetic and functional consequences. The present study was aimed to clinically evaluate and compare the efficiency of NiTi and multistranded stainless steel wire during initial levelling and aligning of crowded lower anteriors. Material and methods: 30 subjects aged between 14 -20 were chosen for the study and divided in to two groups. All the subjects were fully explained about nature, purpose and treatment. Both groups were bonded with 0.022” MBT prescription brackets. After bonding, for Group A patients 0.016” NiTi arch wire was placed and secured with elastomeric modules, similarly for Group B patients 0.0155”multistranded (SS) wire was placed and secured .Time period needed for decrowding of each group was calculated. Result: Average number of days taken by nickel titanium wire in de-crowding mandibular anteriors is 89.67 days while multistranded SS wire took 113.2 days to de-crowd. Even though multistranded wire has low stiffness, because of its shape memory and super elasticity, nickel titanium wire is clinically efficient in decrowding severely crowded lower anteriors. To conclude, a marginal advantage of NiTi wire exists in accordance to the time period taken to decrowd mandibular anteriors.

Failure evaluation after a 6-year retention period: A comparison between glass fiber-reinforced (GFR) and multistranded bonded retainers

The aim of this study was to compare bond failure and breakage rates of two types of bonded lingual orthodontic retainers (GFR and .0175" multistranded stainless steel wire [MST]) after a 6-year retention period. Eighty-five young adults were randomly divided into two groups: 40 subjects received 48 GFR retainers (14 maxillary and 34 mandibular retainers), and 45 subjects received 50 MST retainers (18 maxillary and 32 mandibular retainers). A Fisher's exact test was performed in order to identify significant differences in the percentage of detachment and breakage of the retainers between the groups. The maxillary detachment rates were 21.42% for the GFR group and 22.22% for the MST group; the mandibular detachment rates were 11.76% for the GFR group and 15.62% for the MST group. The maxillary breakage rates were 7.14% for the GFR group and 16.66% for the MST group; the mandibular breakage rates were 8.82% for the GFR group and 15.62% for the MST group. The differences were not statistically significant. GFR and multistranded stainless steel retainers showed similar results in terms of bond failure and breakage after 6 years of retention. The use of GFR retainers as a retention strategy should not be discouraged and could be considered a viable esthetic alternative to stainless steel wire retainers.

Efficiency, behavior, and clinical properties of superelastic NiTi versus multistranded stainless steel wires

To investigate efficiency, behavior, and properties of superelastic NiTi vs multistranded stainless steel wires in Begg and preadjusted edgewise appliance (PEA) under moderate to severe crowding conditions. Ninety-six participants (48 male, 48 female), aged 12-18 years old (mean age = 15.2 ± 1.95), with moderate (≤ 6 mm; mean = 5.3 ± 0.48) to severe (> 6 mm; mean = 7.9 ± 0.66) initial crowding were distributed into four groups: superelastic NiTi PEA (n = 24), superelastic NiTi Begg (n = 24), multistranded (coaxial) stainless steel PEA (n = 25), and multistranded (coaxial) stainless steel Begg (n = 23). In this study, 0.16-inch superelastic (austenitic active) NiTi and 0.175-inch multistranded (six stranded, coaxial) stainless steel wires were used in a 0.022-inch slot (Roth prescription) PEA and Begg appliance with a follow-up of six weeks. Analysis of variance revealed no significant difference in reduction of crowding between superelastic NiTi PEA and multistranded (coaxial) stainless steel PEA groups, but reduction in crowding was significantly greater in the superelastic NiTi Begg group compared with the multistranded (coaxial) stainless steel Begg group with F (3, 44) = 8.896, P < .001, and effect size (ω) 0.57 in moderate crowding and F (3, 44) = 122.341, P < .001, and effect size (ω) 0.93 in severe crowding. Linear regression demonstrated significant (P < .05) positive correlation between amount of initial crowding and reduction in crowding in all groups except the multistranded (coaxial) stainless steel Begg group, wherein a negative correlation did exist. Superelastic NiTi performed significantly better than multistranded (coaxial) stainless steel wire in the Begg appliance. However, in PEA, there was no significant difference.

Mechanical properties and surface characterization of translucent composite wire following topical fluoride treatment

To determine the effects of a fluoride prophylactic agent on the mechanical properties and surface quality of a preformed round translucent composite archwire while comparing it with nickel-titanium (Ni-Ti) and multistranded stainless steel wires. The wires were immersed in an acidulated phosphate fluoride solution (APF) or in distilled water (control) for 1.5 hours at 37°C. Flexural modulus of elasticity (E) and yield strength (YS) of the wires were measured using a three-point bending test in a universal testing machine. The springback ratio (YS/E) was calculated for each wire. The influence of fluoride treatment on properties of the wires was statistically analyzed using Student's t-test at α = .05. Surface changes were observed with a scanning electron microscope. Fluoride treatment produced a statistically significant reduction in E, YS, and YS/E of the composite wire (P < .05). In addition, a significant decrease in E of Ni-Ti wire was found after exposure to fluoride, upon comparison with distilled water control treatment. On the other hand, no significant effect of fluoride treatment was found on YS and YS/E of Ni-Ti wire and on studied properties of the multistranded stainless steel wire (P > .05). Corrosive changes in surface topography were observed after exposure to the fluoride agent and were more pronounced with the composite wire. These results suggest that using a topical fluoride agent with translucent composite wire could decrease the mechanical properties and might damage the surface of the wire, potentially contributing to prolonged orthodontic treatment.

Efficacy of Esthetic Retainers: Clinical Comparison between Multistranded Wires and Direct-Bond Glass Fiber-Reinforced Composite Splints

The purpose of this longitudinal prospective randomized study was to evaluate the reliability of two different types of orthodontic retainers in clinical use: a multistrand stainless steel wire and a polyethylene ribbon-reinforced resin composite. Moreover the level of satisfaction of the patient about the esthetic result was also analyzed by means of a Visual Analogue Scale (VAS). 34 patients (9 boys and 25 girls, mean age 14.3), in the finishing phase of orthodontic treatment, were selected for the study. Since splints were applied the number, cause, and date of splint failures were recorded for each single tooth over 12 months. Statistical analysis was performed using a paired t-test, Kaplan Meier survival estimates, and the log-rank test. Kruskal Wallis test was performed to analyze VAS recordings. Differences between the bond failure rates were not statistically significant. Esthetic result of VAS was significantly higher for polyethylene ribbon-reinforced resin retainers than for stainless steel wires.

Application of fiber-reinforced composite as fixed lingual retainer

To investigate mechanic properties of fiber-reinforced composite (FRC) and its influence on maintaining periodontal health. Sixty patients completing orthodontic treatment were randomized into two groups with FRC and multistrand stainless steel wire (MSSW) being applied as fixed lingual retainer. Bleeding index (BI) and pocket depth(PD) were recorded right after, 6 months and 12 months after bonding the retainer. Flexural modulus and maximum shear bond strength were tested for FRC and MSSW. Statistical significance was found at the increase of BI from right after bonding, 6 months after to 12 months after for both groups (P < 0.05), while no statistically significant change was found in PD among the three time points (P > 0.05). There were no difference between the two groups at each time point regarding BI and PD (P > 0.05). The flexural modulus and maximum shear bond strength of FRC were both below to that of MSSW under the same test situation (P < 0.001). It is necessary to improve the bonding strength of FRC and reduce its negative effect on periodontal health in addition to its advantage of convenience.