Orthodontic Retainers Research Articles

The prevalence of opportunistic pathogens associated with intraoral implants

The aim of this study was to determine the prevalence and proportions of opportunistic pathogens harboured on orthodontic retainers. First, Staphylococcus spp. and Candida spp. were isolated from the retainer's inner surface and from other mucosal surfaces of the subject's mouth by routine bacterial culture. The prevalence and proportions of these micro-organisms on retainers was compared in different areas of the mouth within a group of retainer wearers, and mucosal carriage was compared to a group of nonretainer wearers. Staphylococcus spp. were isolated from 50% of the retainers and comprised on average 8·4% of the viable microbiota. Candida spp. comprised 0·13% of the viable microbiota and were recovered from 66·7% of the retainers. Neither genus was isolated from nonretainer wearers. Second, the two most commonly worn retainers manufactured from different materials were sampled; again Staphylococcus spp. and Candida spp. were recovered; however, no statistical differences were observed between the devices. Opportunistic, nonoral, pathogenic micro-organisms were recovered from orthodontic retainers. It is possible that an orthodontic retainer could be a reservoir for opportunistic pathogens and act as a source of cross-, self- and re-infection.

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.

Low-shrinking composites. Are they reliable for bonding orthodontic retainers?

Objective: To evaluate the shear bond strength (SBS), fracture mode, wire pull out (WPO) resistance and microleakage between low-shrinking and conventional composites used as a lingual retainer adhesive. Methods: A total of 120 human mandibular incisor teeth, extracted for periodontal reasons, were collected. Sixty of them were separated into two groups. To determine the SBS, either Transbond-LR (3M-Unitek) or Silorane (3M-Espe) was applied to the lingual surface of the teeth by packing the material into standard cylindrical plastic matrices (Ultradent) to simulate the lingual retainer bonding area. To test WPO resistance, 20 samples were prepared for each composite where the wire was embedded in the composite materialand cured. Then tensile stress was applied until failure of the composite occurred. The remaining 60 teeth were divided into two groups and multi-stranded 0.0215-inch diameter wire was bonded with the same composites. Microleakage was evaluated by the dye penetration method. Statistical analyses were performed by Wilcoxon, Pearson chi-square, and Mann-Whitney-U tests at p ＜ 0.05 level. Results: The SBS and WPO results were not statistically significant between the two groups. Significant differences were found between the groups in terms of fracture mode (p ＜ 0.001). Greater percentages of the fractures showed mix type failure (85%) for Silorane and adhesive (60%) for Transbond-LR. Microleakage values were lower in low-shrinking composite than the control and this difference was found to be statistically significant (p ＜ 0.001). Conclusions: Low-shrinking composite produced sufficient SBS, WPO and microleakage values on the etched enamel surfaces, when used as a lingual retainer composite. (Korean J Orthod 2011;41(1):51-58)

First Aid for Orthodontic Retainers

The need for long-term retention to prevent post-treatment tooth movement is now widely accepted by orthodontists. This may be achieved with removable retainers or permanent bonded retainers. This article aims to provide simple guidance for the dentist on how to maintain and repair both removable and fixed retainers. The general dental practitioner is more likely to review patients over time and needs to be aware of the need for long-term retention and how to maintain and repair the retainers.

The thumb-sucking deterrent and orthodontic retainer appliance

This case report illustrates a simple and effective removable thumb-sucking deterrent appliance used to treat an 18-year-old female. The thumb-sucking deterrent appliance described is easy to fabricate, requires little adjustment chairside and could easily be used in general dental practice in motivated patients.

Bonded Orthodontic Retainers: A Comparison of Initial Bond Strength of Different Wire-and-Composite Combinations

The aim of this in-vitro study was to evaluate initial bond strength in Newton (N) of two types of wires (Ortho- Flextech chain and Penta-One Coaxial wire 0.0215") bonded with three lingual retainer composites (FlowTain, Light Cure Retainer and Transbond LR). One hundred and eighty sound, extracted human premolars were randomly divided into six equal groups. One of the two types of lingual retainer wires was bonded with one of the three types of the composite material in each group. Initial bond strength was measured using an Instron universal testing machine. We also evaluated the failure characteristics after failure at maximum load using an optical microscope. Our findings demonstrated that the Coaxial/Transbond LR group was statistically significantly stronger than the other combinations. Statistically, 0.0215" Coaxial wire provided significantly stronger bond strength than Ortho-Flextech chain, and when the three composite systems were compared, Transbond LR revealed significantly higher bond strength than the others. However, Transbond LR left significantly more resin on the enamel surface after bond failure. Significant differences exist between different combinations of wires and lingual retainer composites; however, all the wire-and-composite combinations we tested possess sufficient bond strength for clinical application.

The Essential Work of Fracture of Thermoplastic Orthodontic Retainer Materials

To investigate whether oral cleansing agents affect the essential work of fracture (EWF) and plastic work of fracture (PWF) for two types of orthodontic thermoplastic retainer materials. Polyethylene-terephthalate-glycol (PETG; Tru-Tain Splint) and polypropylene/ethylene-propylene rubber (PP-EPR) blend (Essix-C+) sheets were compared. For each material, six sets of 25 sheets were thermoformed into double-edge-notched-tension specimens; subsets of five specimens were formed with internotch distances (L) equal to 6, 8, 10, 12, or 14 mm, respectively. Sets were stored (160 hours, 25 degrees C) in air (DRY), distilled water (DW), Original Listerine (LIS), mint Crest ProHealth (CPH), 3% hydrogen peroxide (HP), or Polident solution (POL). Specimens were fractured in tension at 2.54 mm/min. Areas under load-elongation curves were measured to determine total work of fracture (W(f)). Linear regressions (W(f) vs L [n = 25]) yielded intercepts (EWF) and slopes (PWF). Ninety-five percent confidence intervals were used to evaluate differences in EWF and PWF estimates. PP-EPR blends showed higher EWFs after storage in HP vs storage in DW. PP-EPR blend showed higher EWFs after storage in CPH vs PETG. After HP storage, PP-EPR exhibited lower PWFs than with any other storage conditions. PP-EPR exhibited higher PWFs than PETG after storage in DRY, DW, and LIS. Compared with DW, none of the cleansers decreased the energy to initiate fracture. With one exception, no cleanser decreased the energy to continue plastic fracture extension. In PP-EPR blend, increased resistance to fracture initiation was observed with CPH and HP, yet, surprisingly, HP decreased resistance to plastic fracture growth.

Commentary

I congratulate the authors on a well-designed survey identifying common retention practices in the United States. However, I remind readers that this article describes what orthodontists do. Results of a survey-based study to identify common retention practices in the United StatesAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 137Issue 2PreviewThe purpose of this descriptive study was to use a carefully constructed, pilot-tested survey instrument to identify the most common orthodontic retainers and retention protocols prescribed in the United States as reported by active members of the American Association of Orthodontists. Full-Text PDF

Results of a survey-based study to identify common retention practices in the United States

The purpose of this descriptive study was to use a carefully constructed, pilot-tested survey instrument to identify the most common orthodontic retainers and retention protocols prescribed in the United States as reported by active members of the American Association of Orthodontists. We randomly selected 2000 active members, stratified by region of practice, for the study. Information gathered included, but was not limited to, the types of retainers prescribed in the maxillary and mandibular arches, duration of full-time and part-time wear, use of fixed retainers, appliances fabricated in office vs commercial laboratories, the number of debonds per year, and retention appointment schedules. The survey consisted of 20 questions. Data were gathered on a categorical scale and analyzed. We received 658 responses (32.9%) during a 12-week period. Maxillary Hawley retainers (58.2%) and mandibular fixed lingual retainers (40.2%) were the most commonly used. Most orthodontists prescribed less than 9 months of full-time wear of removable retainers and thereafter advised part-time, but lifetime wear. Most orthodontists (75.9%) did not instruct patients to have the fixed lingual retainers removed at a specific time. More orthodontists who prescribed Hawley retainers recommended longer full-time wear compared with clear thermoplastic retainers. The timing of scheduled retention appointments varied among clinicians and depended on the number of years in practice, the volume of patients debonded, and the type of prescribed retainer. The only regional difference associated with retainer design was the Northeast region, where mandibular fixed lingual retainers were used less frequently. Female orthodontists did not use mandibular fixed lingual retainers as often as their male counterparts. Maxillary Hawley and mandibular fixed lingual retainers are most commonly used. This study is the first to describe retention protocols and the scheduling of retention appointments in the United States.

Mouthguard for relief of repeated clenching stress to cervical restorations during exercises

Mouthguards were used to protect boxers from lip lacerations and other soft tissue injuries in the late 19th century. Now they are used various parts of dental treatment, which are sports protective aid, bleaching tray, orthodontic retainer, implant insertion guide tray, splint and so on. Repeated dislodgement of Class V restoration due to habitual clenching stress should be restored with stress control. Mouthguard can be used as stress relief device. This case describes methods that can relieve occlusal force to teeth by using mouthguard. Satisfactory results can be obtained by using mouthguard for retention of repeated dislodgement Class V restorations. If patients suffered from repeated restorations of Class V due to clenching, mouthguard can be used additional device to relieve the occlusal stress in conservative dentistry.

Glass fibre reinforced versus multistranded bonded orthodontic retainers: a 2 year prospective multi-centre study

The objective of this study was to compare glass fibre reinforced (GFR) with multistranded bonded orthodontic retainers in terms of success rate and periodontal implications. A 2 year parallel study was conducted of 184 patients scheduled to receive bonded retainers in the upper and lower anterior segments. In three centres, the patients (mean age 14 years; 90 males and 94 females) were sequentially assigned to receive GFR retainers containing 500 unidirectional glass fibres (GFR500), 1000 unidirectional glass fibres (GFR1000), or multistranded retainers (gold standard). Retainer failures and periodontal conditions were monitored every 6 months. In a control group of 90 subjects without retainers, periodontal conditions were examined (negative control). Of the 274 recruited patients, 15 dropped out during the 2 year study period. Kaplan-Meier plots were drawn to assess survival of the different retainers. The Mantel-Cox log-rank test was used to identify significant differences in survival functions among the groups. Repeated measures analysis of variance and appropriate post hoc tests were adopted to evaluate periodontal conditions over time. GFR retainers showed unacceptably high failure rates in comparison with multistranded retainers (51 versus 12 per cent). The most significant periodontal conditions were found in patients with GFR retainers with no significant differences between the GFR500 and the GFR1000 group for any parameter at any time point. Subjects without retainers showed significantly lower levels of gingival inflammation and plaque accumulation when compared with patients in any retainer group. Multistranded retainers should remain the gold standard for orthodontic retention, although periodontal complications are common. The use of GFR retainers should be discouraged in daily practice.

Adhesive properties of bonded orthodontic retainers to enamel: stainless steel wire vs fiber-reinforced composites.

The objectives of this study were to compare the bond strength of a stainless steel orthodontic wire vs various fiber-reinforced composites (FRC) used as orthodontic retainers on enamel, analyze the failure types after debonding, and investigate the influence of different application procedures of stainless steel wires on bond strength. Caries-free, intact human mandibular incisors (N = 80, n = 10 per group) were selected and randomly distributed into 8 groups. After etching with 37% H3PO4 for 30 s, rinsing and drying, bonding agent (Stick Resin) was applied and light polymerized. Then one of the following FRC materials was applied on the flowable composite (Stick Flow) using standard molds: group 1: Angelus Fibrex Ribbon; group 2: DentaPreg Splint; group 3: ever-Stick Ortho; group 4: Ribbond. In group 5, Quad Cat Wire was applied in the same manner as in FRC groups. In group 6, after applying bonding agent (Stick Resin), Quad Cat Wire was placed directly on the tooth surface and covered with Stick Flow composite. In group 7, after bonding agent (Heliobond) was applied, Quad Cat Wire was placed directly on the tooth surface and covered with Tetric Flow composite. In group 8, after applying bonding agent (Heliobond) and polymerization, Tetric Flow composite was applied, not polymerized, and Quad Cat Wire was placed and covered with Tetric Flow again. Specimens were thermocycled for 6000 cycles between 5 degrees C and 55 degrees C and loaded in a universal testing machine under shear stress (crosshead speed: 1 mm/min) until debonding occurred. The failure sites were examined under an optical light microscope. Data were analyzed using one-way ANOVA and the Tukey-Kramer adjustment test (alpha = 0.05). Significant differences were found between the groups (p = 0.0011) (ANOVA). Bond strength results did not significantly differ either between the FRC groups (groups 1 to 4) (6.1 +/- 2.5 to 8.4 +/- 3.7 MPa) (p > 0.05) or the wire groups (groups 5 to 8) (10.6 +/- 3.8 to 14 +/- 6.7 MPa) (p > 0.05). Failure types varied within the FRC groups, but mainly composite was found left adhered on the enamel surface at varying degrees. In the stainless steel wire groups, when the retainer was applied onto the bonding agent and then covered with flowable resin, partially attached composite on the enamel was often found after debonding. When the wires were embedded in the flowable composite, the Heliobond group (group 8) showed more adhesive failures between the enamel and the composite compared to group 5, where the bonding agent was Stick Resin. Regardless of their application mode, stainless steel orthodontic bonded retainers delivered higher bond strengths than those of fiber retainers. The differences were statistically significant compared to those of Angelus Fibrex Ribbon and DentaPreg Splint.

Resin-modified glass ionomer cements for bonding orthodontic retainers

The aims of this study were to evaluate the shear bond strength (SBS), fracture mode, and wire pull out (WPO) resistance between resin-modified glass ionomer cement (RMGIC) and conventional orthodontic composite used as a lingual retainer adhesive. Forty lower human incisors were randomly divided into two equal groups. To determine the SBS, either Transbond-LR or Fuji Ortho-LC was applied to the lingual surface of the teeth by packing the material into cylindrical plastic matrices with an internal diameter of 2.34 mm and a height of 3 mm (Ultradent) to simulate the lingual retainer bonding area. To test WPO resistance, 20 samples were prepared for each composite where the wire was embedded in the composite material and cured, 20 seconds for Transbond-LR and 40 seconds for Fuji Ortho-LC. The ends of the wire were then drawn up and tensile stress was applied until failure of the resin. A Student's t-test for independent variables was used to compare the SBS and WPO data. Fracture modes were analyzed using Pearson chi-square test. Significance was determined at P < 0.05. The SBS values were 24.7 +/- 9.2 and 10.2 +/- 5.5 MPa and the mean WPO values 19.8 +/- 4.6 and 11.1 +/- 5.7 N for Transbond-LR and Fuji Ortho-LC, respectively. Statistical analysis showed that the SBS and WPO values of Transbond-LR and Fuji Ortho-LC were significantly different (P < 0.001). No significant differences were present among the groups in terms of fracture mode. However, the RMGIC resulted in a significant decrease in SBS and WPO; it produced sufficient SBS values on the etched enamel surfaces, when used as a bonded orthodontic retainer adhesive.

Three-Dimensional Measurement of the Mandible After Mandibular Midline Distraction Using a Cemented and Screw-Fixated Tooth-Borne Appliance: A Clinical Study

The aim of this study was to analyze the 3-dimensional movement of the mandible segments after distraction of the mandibular midline by use of a cemented and screw-fixated tooth-borne appliance. Twenty patients with transverse deficiencies of the lower arch were included in a consecutive study. Before surgical intervention, a custom-made appliance was cemented to the teeth and also fixed with 2 screws between the teeth on each side. The distraction appliance was activated after 5 days at a rate of 0.6 mm/d. After a consolidation period of 6 weeks, the appliance was removed and an orthodontic retainer was applied. Radiographs and cast models were taken preoperatively and postoperatively, and direct linear measurements were performed at the same intervals. Mean expansion (+/- SD) of the osteotomy line measured on the radiographs for the superior, middle, and inferior part of the mandible was 5.1+/-2.4, 5.9+/-2.8, and 5.7+/-2.9 mm, respectively. The mean overall expansion was 5.6+/-2.6 mm. The width increase of the models between the canines, first premolars, second premolars, first molars, and second molars was 4.2+/-1.8, 5.0+/-2.0, 4.7+/-2.0, 4.3+/-1.7, and 3.6+/-1.3, respectively, at the tooth level and 3.4+/-2.0, 3.6+/-1.8, 3.3+/-1.4, 3.2+/-1.5, and 2.2+/-1.8, respectively, at the bone level. Expansion of the osteotomy line in the vertical dimension showed a uniform pattern. Lateral movements of the mandibular segments decreased from the symphysis to the gonial angles. The positional changes of the teeth and the bone segments were proportionate. Minimal dental movement was observed.

Shear modulus of 5 flowable composites to the EverStick Ortho fiber-reinforced composite retainer: An in-vitro study

Although fiber-reinforced composites (FRC) are now available for use as orthodontic retainers, little is known about their bonding properties. Our aim in this study was to investigate the adhesive properties of various composites to a commercially available FRC retainer. Five flowable composites (Grandio Flow [Voco GmbH, Cuxhaven, Germany], Synergy Flow [Coltène/Whaledent AG, Genf, Switzerland], Tetric Flow [Ivoclar Vivadent AG, Schaan Fürstentum, Liechtenstein], Tetric Flow Chroma [Ivoclar Vivadent AG], and Transbond LR [3M Unitek, Monrovia, Calif) were tested for their shear bond strengths to the EverStick Ortho (Stick Tech Ltd Oy, Turku, Finland) FRC retainer stick. Each group contained 15 samples and underwent 1000 aging cycles between 5 degrees C and 55 degrees C. A testing machine was used to measure the shear bond strengths at the composite-FRC interface. All specimens were visually controlled for the location of the fracture line. Typical shear bond strengths were measured at 40 N or 8 MPa. No significant difference was found between the 5 composites (ANOVA, P < or = 0.05). The fracture line was consistently in the FRC retainer. All composites had similar bonding characteristics, and visual inspection consistently showed fractures in the FRC retainer. Because the point of least resistance was in the retainer, we concluded that all tested composites were equally effective.

Allergy to auto-polymerized acrylic resin in an orthodontic patient

This article reports on a 60-year-old woman who had an allergic reaction to methylmethacrylate self-curing acrylic resin during orthodontic treatment. A localized hypersensitive reaction appeared on the palate after an orthodontic retainer was placed. Samples of the acrylic were removed and analyzed with gas chromatography to evaluate the residual monomer level. The residual monomer content was between 0.745% and 0.78%, which did not exceed international standards for this material. Patch tests were performed with several methylmethacrylate resin samples and processed with various techniques; they showed positive reactions. Despite the many alternative products available, self-curing acrylic resin remains widely used because of its low cost, ease of use, and diversity of indications. Orthodontists should be aware that allergic reactions can occur.

What type of orthodontic retainer is best?

Data sources The Cochrane Oral Health Group's Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL), Medline and Embase were searched. Several journals were searched by hand (American Journal of Orthodontics and Dentofacial Orthopedics (formerly American Journal of Orthodontics), Angle Orthodontist European Journal of Orthodontics, Journal of Orthodontics (formerly British Journal of Orthodontics)). No language restrictions were applied. Authors of published reports of randomised controlled trials (RCT) were identified and contacted to identify further unpublished trials. The most recent search made was in December 2002. Study selection Only RCT were chosen for inclusion. Studies included children and adults who had retainers fitted or adjunctive procedures undertaken after orthodontic treatment with braces to prevent relapse. The outcomes were how well the teeth were stabilised, survival of retainers, adverse effects on oral health and quality of life. Data extraction and synthesis Screening of eligible studies, assessment of methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. Because no two studies compared the same retention strategies (interventions), it was not possible to combine the results of any studies. Results Four trials satisfied the inclusion criteria. These trials all compared different interventions: circumferential supracrestal fiberotomy (CSF) combined with full-time removable retainer versus a full-time removable retainer alone; CSF combined with a nights-only removable retainer versus a nights-only removable retainer alone; removable Hawley retainer versus a clear overlay retainer and three types of fixed retainers versus a removable retainer. There was weak unreliable evidence, based on data from one trial, that there was a statistically significant increase in stability in both the mandibular (P<0.001) and maxillary anterior segments (P<0.001) when the CSF was used, compared with when it was not used. There was also weak, unreliable evidence that teeth settle quicker with a Hawley retainer than a clear overlay retainer, after 3 months. The quality of the trial reports was generally poor. Conclusions There are insufficient research data on which to base our clinical practice on retention at present. There is an urgent need for high-quality RCT in this crucial area of orthodontic practice.

In Situ Effect of 10% Carbamide Peroxide on Resin‐Dentin Bond Strengths: A Novel Pilot Study

This pilot study used a novel study design to evaluate the effect of a 10% carbamide peroxide bleaching gel on the bond strength of a resin-based composite system to dentin. Dentin disks were obtained from human third molars, polished to 600 grit, and mounted on the palatal aspect of a removable orthodontic retainer. Two disks were exposed to a 10% carbamide peroxide bleaching gel for 2 h/d for 21 days, whereas two disks were not treated and served as controls. A retainer was worn by the participant regardless of whether bleaching was used, simulating the action of the saliva/oral fluids on the dentin specimens. After the treatment phase, the dentin disks were retrieved and a resin-based composite system was applied to the specimens following manufacturer's instructions. Composite dentin "sticks" were obtained and tested in microtensile mode. Bond strength values were obtained for treated (n = 20) versus nontreated (n = 26) dentin and were analyzed statistically. Mean bond strengths values (SD) were 29.9 MPa (6.2) and 39.2 MPa (5.8) for treated and nontreated dentin specimens, respectively (p < .001). The results of this study suggest that nightguard (home) bleaching with 10% carbamide peroxide for 2 h/d for 21 days significantly affects resin-dentin bond strengths when dentin is exposed to bleaching material. CLINICAL SIGNIFICANCE The findings of this novel pilot study imply that dentin bonding, such as to exposed root surfaces and cervical areas of the teeth, should not be performed immediately after bleaching with 10% carbamide peroxide.

Time-saving fixed lingual retainer using DuraLay resin transfer

There is general agreement on the necessity of fixed lingual retainers to prevent relapse in many patients after active orthodontic treatment. 1 Bearn D.R. Bonded orthodontic retainers a review. Am J Orthod Dentofacial Orthop. 1995; 108: 207-213 Abstract Full Text Full Text PDF PubMed Scopus (114) Google Scholar , 2 Cerny R. Permanent fixed lingual retention. J Clin Orthod. 2001; 35: 728-732 PubMed Google Scholar , 3 Durbin D.D. Relapse and the need for permanent fixed retention. J Clin Orthod. 2001; 35: 723-727 PubMed Google Scholar Several methods for delivering fixed lingual retainers have been introduced. 2 Cerny R. Permanent fixed lingual retention. J Clin Orthod. 2001; 35: 728-732 PubMed Google Scholar , 4 Corti A.F. Technique clinic an indirect-bonded lingual retainer. J Clin Orthod. 1991; 25: 631-632 PubMed Google Scholar , 5 Haydar B. Haydar S. An indirect method for bonding lingual retainers. J Clin Orthod. 2001; 35: 608-610 PubMed Google Scholar , 6 Becker A. Goultshin J. The multistranded retainer and splint. Am J Orthod. 1984; 85: 470-474 Abstract Full Text PDF PubMed Scopus (17) Google Scholar , 7 Bantleon H.P. Droschl H. A precise and time-saving method of setting up an indirectly bonded retainer. Am J Orthod Dentofacial Orthop. 1988; 93: 78-82 Abstract Full Text PDF PubMed Scopus (4) Google Scholar , 8 Liou E.J.W. Chen L.I.J. Huang C.S. Nickel-titanium mandibular bonded lingual 3-3 retainer for permanent retention and solving relapse of mandibular anterior crowding. Am J Orthod Dentofacial Orthop. 2001; 119: 443-449 Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar , 9 Karaman A.I. Kir N. Belli S. Four applications of reinforced polyethylene fiber material in orthodontic practice. Am J Orthod Dentofacial Orthop. 2002; 121: 650-654 Abstract Full Text Full Text PDF PubMed Scopus (65) Google Scholar However, bonding a lingual retainer is still challenging because it requires long working time and has a risk of contamination from saliva and moisture, which can cause bonding failure. In addition, it is difficult to adapt the retainer wire to perfectly fit the lingual surfaces of an anterior tooth. We developed a method of fabricating a fixed lingual retainer using DuraLay resin (Reliance Dental Manufacturing, Worth, Ill) and have used this method with satisfactory results for nearly 10 years on thousands of patients. This technique has proven to be a reliable, convenient, and time-saving procedure.

Wear comparison of thermoplastic materials used for orthodontic retainers

Clear thermoplastic retainers are an alternative to fixed lingual retainers and removable Hawley appliances. However, thermoplastic retainers have demonstrated poor wear resistance and durability after only a few months of use. In this study, a simulated wear device was used to compare the wear of different thermoplastic materials used for orthodontic retainers. Three thermoplastic products were evaluated: C+ (Raintree Essix, New Orleans, La), .040-in Invisacryl C (Great Lakes Orthodontics, Towanda, NY), and .040-in TR sheet material (Bay Dental Direct, Bay City, Mich). Twenty specimens were fabricated for each group. The specimens were vacuum thermoformed according to the manufacturers' recommendations and subjected to wear for 1000 cycles in a wear apparatus with steatite ceramic abraders. Depth of wear was determined by surface profilometry. The maximum peak-to-valley measurement was recorded for each specimen. Mean wear (SD) in microns was as follows: C+, 5.9 (2.4); Invisacryl C, 6.1 (2.6); and TR, 1.6 (0.9). One-way analysis of variance detected a significant difference between groups ( P < .001). TR material, a hard polyethylene terephthalate glycol copolymer (PETG), demonstrated greater resistance to wear than did the other 2 materials, which were softer, polypropylene-based thermoplastics. There was no evidence to suggest a difference in mean wear between the 2 polypropylene-based materials ( P > .05).