The bonded orthodontic retainer constructed from composite and multistrand orthodontic wire provides an esthetic and efficient system for maintained retention. This study was designed to measure shear bond strength of bonded retainers and to suggest a optimal combination of a multistrand wire and bonding method used when bonded retainer was fabricated. 160 sound maxillary and mandibular premolars were used for 80 test samples. After Uniformizing bonding area, length of wire, and thickness of composite, multistrand wire was bonded to fabricated a bonded retainer by direct or indirect bonding method. Shear bond strength and extension length of each sample were measured by a universal testing machine. The results of this study were as follows: 1. In vitro shear bond testing found 6-stranded, 0.0155 inch wires to have the largest shear bond strength and 3-stranded, 0.0195 inch wires to have the least shear bond strength. But, These difference was not statistically significant(p<0.05). 2. In vitro extension testing found 3-stranded, 0.0155 inch wires to have the largest extension length and 3-stranded, 0.0195 inch wires to have the least extension length(p<0.05). The larger diameter wire was used, the larger extension length was shown. But, the strand of wire is not related to the extension length of wire. 3. In comparison with direct bonding method, larger shear bond strength and extension length was shown in indirect bonding method(p<0.05).
Bicuspid ; Orthodontic Retainers ; Orthodontic Wires

OBJECTIVETo evaluate the changes of the occlusal contact characteristics in adolescent patients during 12 months after active orthodontic treatment.

METHODSTwenty adolescent patients with Hawley retainers after active orthodontic treatment were divided into none occlusal interference group and occlusal interference group. The occlusion of the patients was examined with T-Scan II system directly after the appliance removal (T1) and after an average retention period of 12 months (T2). The changes of occlusal contact characteristics were observed.

RESULTSThe disclusion time during protrusion, left and right lateral movements reduced significantly. The average disclusion time decreased [from (1.07 ± 0.87), (0.91 ± 0.47), (0.76 ± 0.43) s to (0.43 ± 0.25), (0.67 ± 0.41), (0.50 ± 0.27) s] significantly (P < 0.05). The occlusal interference disappeared in 4 patients and 1 patient with occlusal interference showed masticatory muscle symptom. The dynamic occlusion [from (1.25 ± 1.11), (0.84 ± 0.15), (0.52 ± 0.49) s to (0.35 ± 0.15), (0.36 ± 0.15), (0.33 ± 0.11) s] improved significantly (P < 0.05) in none occlusal interference group after retention and no statistical differences were found in the occlusal interference group (P > 0.05).

CONCLUSIONSThe overall dynamic occlusion improved after retention in patients with retainers. The presence of occlusal interference affected the self-improvement process and increased the chance of the disorders of stomatognathic system, such as mandibular abnormal movements. Therefore, functional occlusion evaluation and final detailing were needed before appliance removal.

Adolescent ; Dental Occlusion ; Humans ; Orthodontic Retainers

OBJECTIVE: The aim of this study was to examine the properties of fiber-reinforced composite and stainless steel twisted retainers for orthodontic retention. METHODS: Three different span lengths (5.0, 8.0, and 14.0 mm) of fiber-reinforced composite were investigated. The three fiber-reinforced composite retainer groups were subdivided according to the storage condition (dry and wet), resulting in a total of six groups. Each stainless steel and fiber-reinforced composite group was comprised of six specimens. The three-point bending flexural test was conducted using a universal testing machine. ANOVA was used to assess differences in the maximum load and maximum stress according to the span length, material, and storage condition. Post-hoc comparisons were performed if necessary. RESULTS: The maximum stress and maximum load were significantly (p < 0.001) associated with the span length, material, and storage condition. The significant interaction between the material and span length (p < 0.001) indicated the differential effects of the material for each span length on the maximum stress and maximum load, with the difference between materials being the highest for the maximum span length. CONCLUSIONS: Our findings suggest that fiber-reinforced composite retainers may be an effective alternative for orthodontic retention in patients with esthetic concerns or allergy to conventional stainless steel wires.
Humans ; Hypersensitivity ; Orthodontic Retainers* ; Polymers* ; Stainless Steel*

OBJECTIVEThis study investigated the influence of Hawley retainer and vacuum-formed retainer on the articu-lation of Chinese speech of adult orthodontic patients.

METHODSA total of 20 volunteers were recruited in this randomized controlled trial in accordance with the inclusion criteria. Participants were randomly distributed into two groups, namely, the Hawley retainer group and the vacuum-formed retainer group. Speech performance was evaluated at the following time inter-vals: before wearing retainers (T0), immediately after wearing both upper and lower retainers (T1), 24 h later (T2), 1 week later (T3), and 1 month later (T4). The phonetic parameters were acquired through the use of computer-based voice analysis software Praat version 5.4.21, and the final data were analyzed using SPSS 19.0.

RESULTSBoth retainers can influence the phonetic parameters of vowels /e/, /i/, and /ü/ and consonants /s/, /f/, /x/, /t/, /j/, and /q/. However, the Hawley retainer showed a more remarkable effect on the articulation of Chinese speech, and the distortion of /i/, /ü/, and /s/ sounds can last for more than 1 month. Nevertheless, the recovery period of the patients' phonetic function in the vacuum-formed retainer group was within 1 month.

CONCLUSIONSBoth retainers can induce distortion of some Chinese vowels and consonants in the speech of adult orthodontic patients, but the Hawley retainer can more significantly influence the articulation of Chinese speech than vacuum-formed retainer.
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Adult ; Humans ; Orthodontic Appliance Design ; Orthodontic Retainers ; Speech ; Vacuum

Clear thermoplastic retainers have been widely used in daily orthodontics; however, they have inherent limitations associated with thermoplastic polymer materials such as dimensional instability, low strength, and poor wear resistance. To solve these problems, we developed a new type of clear orthodontic retainer that incorporates multi-layer hybrid materials. It consists of three layers; an outer polyethylenterephthalate glycol modified (PETG) hard-type polymer, a middle thermoplastic polyurethane (TPU) soft-type polymer, and an inner reinforced resin core. The resin core improves wear resistance and mechanical strength, which prevent unwanted distortion of the bucco-palatal wall of the retainer. The TPU layer absorbs impact and the PETG layer has good formability, optical qualities, fatigue resistance, and dimensional stability, which contributes to increased support from the mandibular dentition, and helps maintain the archform. This new type of vacuum-formed retainer showed improved mechanical strength and rate of water absorption.
Absorption ; Dentition ; Fatigue ; Orthodontic Retainers* ; Orthodontics ; Polymers ; Polyurethanes ; Water

The popularity of clear overlay retainers (CORs) has increased recently because of their advantages such as better esthetics, cost effectiveness, easy fabrication, and good compliance. However, a deficiency in posterior occlusal settling is a reported limitation of CORs. The aim of this study was to evaluate the posterior occlusal contact changes in a new type of clear orthodontic retainer called Oral-treaper (OTP), which consists of three layers and has stronger mechanical characteristics than do conventional retainers. Three patients who completed fixed orthodontic treatment received OTP as a removable retainer. Cast models were fabricated after the removal of fixed appliances (T1) and after 4 to 11 months of using the retainers (T2). We evaluated all the cast models to compare the post-orthodontic settling pattern during the use of the OTPs. The depth of occlusal contacts was evaluated using color maps. The OTP did not prevent vertical settling in all patients but resulted in an improvement in posterior occlusal contact points.
Compliance ; Cost-Benefit Analysis ; Esthetics ; Humans ; Orthodontic Retainers

Aesthetic and comfortable transparent retainers and clear plastic appliances are becoming increasingly popular, and their components, especially thermoplastic materials, are gradually attracting widespread interest. Orthodontic thermoplastic materials are versatile polymers, and thus their properties, such as force delivery, force relaxation, and aging properties have been comprehensively studied. Meanwhile, blending modification technology has been applied for the acquisition of novel materials with enhanced characteristics. In this paper, we review the types and properties of thermoplastic materials, the development process they undergo, factors that influence their properties, and some development prospects.
Esthetics, Dental ; Materials Testing ; Orthodontic Retainers ; Plastics ; Polymers

No abstract available.
Incisor ; Malocclusion ; Orthodontics, Corrective ; Orthodontic Brackets ; Orthodontic Retainers ; Dental Arch ; Mandible

OBJECTIVETo evaluate the craniofacial and occlusional changes of Class II patients treated with Tip-Edge Plus technique.

METHODSTwelve Class II patients (7 girls and 5 boys, mean age 14.3 years) with bimaxillary or maxillary protrusion were selected. All the patients were four first premolar extraction cases and treated with Tip-Edge Plus technique. Cephalometric analysis was performed to evaluate the changes before and after treatment.

RESULTSAfter treatment, the profile was greatly improved. UL-E, LL-E were decreased significantly (P < 0.01) and incisors were retracted (P < 0.05). Upper molars moved forward slightly (P > 0.05).

CONCLUSIONSThe anchorage control in Tip-Edge Plus technique was effective without extraoral force, palatal arch and implants. Under very light force, the crown of anterior teeth tipped distally and lingually quickly. In the final stage, it was possible to achieve both desired root uprighting and crown torque.

Adolescent ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; therapy ; Orthodontic Retainers ; Orthodontics, Corrective ; instrumentation ; methods

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.
Adhesives ; Dental Enamel ; Humans ; Incisor ; Orthodontic Retainers ; Plastics ; Resin Cements ; Shear Strength ; Silorane Resins ; Tooth