Superelastic Nickel-titanium Wires Research Articles

Uprighting horizontally impacted third molars by super-elastic nickel-titanium wire in patients with an extracted first molar.

Protracting lower second molars and uprighting horizontally impacted third molars is a significant orthodontic challenge in patients who require the extraction of severely decayed first molars. Here, we describe the use of biomechanics to upright 90°-tilted lower third molars following second molar protraction. Herein, we introduce a technique for uprighting the lower third molars by (1) the placement of superelastic nickel titanium archwires, (2) bonding, and (3) repositioning of a buccal tube in a tilted position to compensate for the efficiency of Ni-Ti (nickel-titanium) wire. The treatment mechanics used for our two cases showed that even severely impacted third molars can be uprighted by routine continuous straight-wire techniques. This technique proved to be a simple, efficient and reliable treatment option for uprighting horizontally impacted third molars.

Effectiveness of laser-engineered copper-nickel titanium versus superelastic nickel-titanium aligning archwires: A randomized clinical trial.

: To compare the effectiveness of laser-engineered copper-nickel titanium (SmartArch) and superelastic nickel-titanium (SENT) archwires in aligning teeth and inducing root resorption and pain experienced by patients. : Two-arm parallel groups with a 1:1 allocation ratio were used. The participants were patients aged 11.5 years and older with 5-9 mm of mandibular anterior crowding who were indicated for non-extraction treatment. The primary outcome was alignment effectiveness, assessed using Little's irregularity index (LII) over 16 weeks with a single wire (0.016-inch) in the SmartArch group and 2 wires (0.014- and 0.018-inch) in the SENT group (8 weeks each). Secondary outcomes included root resorption evaluated by pre- and post-intervention periapical radiographs and pain levels recorded by the participants during the first week. : A total of 40 participants were randomly allocated into 2 groups; 33 completed the study and were analyzed (16 in the SmartArch group and 17 in the SENT group, aged 16.97 ± 4.05 years). The total LII decrease for the SmartArch and SENT groups was 5.63 mm and 5.29 mm, respectively, which was neither statistically nor clinically significant. Root resorption was not significantly different between the groups. The difference in pain levels was not statistically significant for the first 5 days following wire placement; however, there was a significant difference favoring the SENT group in the final 2 days. : SmartArch and SENT archwires were similarly effective during the alignment phase of orthodontic treatment. Root resorption should be observed throughout the treatment with either wire. SmartArch wires demonstrated higher pain perception than SENT wires.

Properties of Superelastic Nickel-Titanium Wires after Clinical Use.

The aim of the present study was to describe and determine changes in the superelastic properties of NiTi archwires after clinical use and sterilization. Ten archwires from five different manufacturers (GAC, 3M, ODS, GC, FOR) were cut into two segments and evaluated using a three-point bending test in accordance with ISO 14841:2006. The center of each segment was deflected to 3.1 mm and then unloaded to 0 N to obtain a load-deflection curve. Deflection at the end of the plateau and forces at 3, 2, 1 and 0.5 mm on the unloading curve were recorded. Plateau slopes were calculated at 2, 1 and 0.5 mm of deflection. Data obtained were statistically analyzed to determine differences (p < 0.001). Results showed that the degree of superelasticity and exerted forces differed significantly among brand groups. After three months of clinical use, FOR released a greater force for a longer activation period. GC, EURO and FOR archwires seemed to lose their mechanical properties. GC wires released more force than other brand wires after clinical use. Regarding superelasticity after sterilization, GAC, 3M and FOR wires recovered their properties, while EURO archwires lost more.

Loads of continuous mechanics for uprighting the second molar on the second molar and premolar

This paper aims to evaluate the effect of tube height on uprighting a mandibular second molar with a continuous arch, specifically the main effects on the molar tube and the side effects on the second premolar bracket. Slot brackets (0.18-in) and tubes were passively bonded from the left second molar to the right second premolar of the patient's cast and fixed to an orthodontic force tester. A mesially tipped second molar along with its tube was positioned at 5 different heights in relation to the bracket slots of the remaining appliance: 2 mm below (group -2), 1 mm below (group -1), leveled (group 0), 1 mm above (group 1) and 2 mm above (group 2). Each group had 10 different 0.016 × 0.022-in superelastic nickel-titanium wires tied one at a time to the appliance to register the vertical forces (Fz) and tipping moments (Mx) produced at the molar tube and the premolar bracket, statistically. Analysis of variance was used to identify differences of load among the groups for wire response to the position of the tube in relation to the other brackets' slots. As the molar tube was positioned more occlusally, Fz and Mx decreased at the molar tube from 1.31 N to 0.75 N and 13.98 N.mm to 11.84 N.mm, respectively, whereas at the premolar bracket, Fz and Mx decreased from 1.52 N to 0.88 N and 8.77 N.mm to 1.05 N.mm, respectively. In all groups, the load system at the molar tube (the main effects) registered a distal tipping moment and an extrusive force, whereas at the premolar bracket, the load system (side effects) included a distal tipping moment and an intrusive force. As the tube moved occlusally, the extrusive force and the uprighting moment decreased, along with the side effects at the premolar bracket. Attempting to bond the molar tube more occlusally (within reasonable intraoral dimensions) when trying to upright a molar does not appear to be sufficient to keep a molar from extruding.

Treatment of Class II malocclusion with the improved superelastic nickel-titanium alloy wire and long hooks for mandibular molar protraction

• Two patients were treated with extraction of the mandibular second premolars. • We used superelastic nickel-titanium alloy wires as working wires. • The use of nickel-titanium wires and long hooks worked to mesialize the molar bodily. The mandibular first molar must be carefully moved to prevent mesial tipping and extrusion in case extraction of the mandibular second premolar is required to achieve the desired goals. The nickel-titanium alloy has unique mechanical properties, including superelasticity and shape memory, leading to the generation of continuous light forces that may be more biologically compatible than intermittent strong forces. However, it provides poor root control because of its low stiffness. We herein have experienced the patients with Angle Class II malocclusion that uses the improved superelastic nickel-titanium wire (ISW) and long hooks to achieve bodily movement of the mandibular first molar. The 0.022 × 0.028-in slot preadjusted edgewise appliances and 0.020 × 0.025-in ISWs as the working archwire were used. We pinched the crimpable long hooks on the rectangular ISW and applied 100-150 g of contractile force between the fixed long hooks and bracket hooks of the mandibular first molars to activate the system with ligature wire lacing. The mandibular molars were uprighted and mesially moved; panoramic radiographs did not indicate severe root resorption. These experiences suggest that this method involving the combined use of the ISW and long hooks may be one of the useful methods for closing spaces by facilitating the uprighting and mesial movement of the molars in treating Class II malocclusion.

A clinical comparison of the effectiveness of two types of orthodontic aligning archwire materials: a multicentre randomized clinical trial.

To compare the heat-activated nickel titanium (HANT) with superelastic nickel-titanium (SENT) archwires in terms of their effectiveness of aligning teeth, possibility of inducing root resorption, and perception of pain. Orthodontic patients aged 12 years or over with mandibular anterior crowding of 3-6 mm, who required treatment without extractions were randomly allocated (a simple non-stratified randomization) to the HANT and SENT archwires groups with a 1:1 allocation ratio. The archwire sequence in both groups was 0.014-inch and 0.016-inch, respectively. Each archwire was placed for 4 weeks. The outcome measures included the amount of crowding assessed blindly using Little's irregularity index (LII), apical root resorption, and pain perception. The effectiveness of alignment was tested using 2 × 2 mixed factorial analysis of variance (ANOVA) model, while root resorption and pain perception were tested by the Mann-Whitney U-test and Wilcoxon signed-rank test (P < 0.05). Thirty-four patients were randomized and recruited from four centres, of those 31 were analysed (15 participants for the HANT and 16 for the SENT groups) with an overall mean age of 19.13 ± 5.73 years. The total reduction in the LII was 2.69 mm and 2.74 mm for the HANT and SENT groups, respectively. This did not reach the level of statistical (P = 0.809) or clinical significance. Similarly, root resorption and pain perception showed non-significant difference between groups. However, there was a slight increase in root resorption with the SENT group. A long-term evaluation of root resorption is required. Both HANT and SENT archwires were equally effective in the aligning stage of orthodontic treatment. Root resorption with SENT wires should be monitored throughout treatment. The trial was registered with ClinicalTrials.gov on 18 September 2019, registration number: NCT04090931.

Comparison of the load-deflection characteristics of 0.012″ heat-activated, superelastic and bent superelastic nickel titanium wires

PurposeTo compare the characteristics and load-deflection graphs of 0.012″ heat-activated NiTi, superelastic NiTi and bent (bends placed at 1, 2 and 3mm) superelastic NiTi wires, focusing on force at 0.5mm after deactivation after deflection by 1, 2, 3 and 4mm. Materials and methodsThree-bracket bending tests using a 10N load cell with 1mm/min crosshead speed and 8mm span were performed at 37°C. Three groups of wires, 0.012″ heat-activated NiTi wires (HANT), superelastic NiTi wires (S), and superelastic NiTi wires with bends placed at 1, 2 and 3mm (SB1, SB2 and SB3, respectively) were deflected by 1, 2, 3 and 4mm. Deactivation forces (N) at 0.5mm after deactivation were compared using ANOVA. ResultsBent NiTi wires produced lighter forces than superelastic and heat-activated NiTi wires (P<0.05). Superelastic and heat-activated NiTi wires had linear load-deflection graphs at 1mm deflection. No bent NiTi wires had linear load deflection graphs; hysteresis was observed after 2, 3 and 4mm deflection in all NiTi groups. Increasing the number of bends and deflection appeared to inactivate NiTi wires. ConclusionsAfter any deflection, all bent NiTi wires produce lighter forces at 0.5mm after deactivation than superelastic NiTi and heat-activated NiTi wires. This study indicates bending a NiTi wire close to a displaced tooth with up to 1mm deflection can produce an active light deactivation force to level severely displaced teeth.

THE DIFFERENCE OF SURFACE MORPHOLOGY AND CHEMICAL COMPOSITION OF SUPER-ELASTIC NICKEL TITANIUM ORTHODONTIC WIRES BEFORE AND AFTER IN ARTIFICIAL SALIVA SUBMERSION

Objective: In order to Investigate the difference of morphology and composition of Super-elastic Nickel Titanium wire before and after submersed in artificial saliva with normal pH (pH 6:50) and acidic pH (pH 3.75). Material and method: Super-elastic Nickel Titanium wire were divided into 2 groups. Each group consisted of 3 samples submerged in 150 ml of artificial saliva for 28 days. The first group was Super-elastic Nickel Titanium wire submersed in artificial saliva with normal pH (pH 6.50) while the second group was submersed in artificial saliva with acidic pH (pH 3.75). Wire surface morphology was Analysed using Scanning Electron Microscope (SEM) while the wire composition was Analysed using Energy Dispersive X-ray Spectroscopy (EDS. Result: Scanning Electron Microscope revealed a significant difference of surface morphology of super-elastic nickel titanium before and after submersed in artificial saliva between normal pH (pH 6.0) and acidic pH (pH 3.75). SEM investigation Showed a fibrous microstructure on the surface of superelastic nickel titanium before submersed in artificial saliva and became rough and showed many form of pitting or crevice corrosion after submersed in artificial saliva for 28 days. The chemical compositions in surface morphology were analysed using EDS Also showing a different result. The major compositions of super-elastic nickel titanium wire were the C, N, Ni and Ti and after submersed in artificial saliva for 28 days has made any additional elements O, Al, Si, P, Cl, Ca, K and Fe. Conclusion: the surface morphology of nickel titanium surface rugosity greater SEM Showed and presence of many forms of pitting or crevice corrosion after submersed in artificial saliva with normal pH and acidic pH. The major surface composition of a super-elastic nickel titanium before submersed in artificial saliva were the C, N, Ni and Ti and as a major composition of super-elastic nickel titanium before and after submersed in artificial saliva with normal pH (pH 6.0) and acidic pH (pH 3.75 ).

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. 

Residents' journal review

Mandibular tooth size-arch length discrepancy is a common problem that orthodontists encounter. Many times, this is associated with a mandibular transverse discrepancy. The purpose of this study was to compare 3 osteotomy approaches, as well as 3 biomechanical force applications, using finite elemental analysis to select the optimal approach for expansion of the mandible for future clinical use. A cone-beam computed tomography scan of an adult mandible was obtained, and with Mimics software, a 3-dimensional geometric model was created. Then, using the Rapidform software, the teeth, mucosa, trabecular bone, periodontal ligament, and cortical bone were generated. The final finite elemental model was then generated from the geometric model (ANSYS, Swanson Analysis System). Three osteotomy approaches were used: midline symphyseal (traditional), angulated midline symphyseal (novel approach), and parasymphyseal step (novel approach) osteotomies. Tooth-borne, hybrid-borne, and bone-borne pure horizontal forces were applied to each osteotomy approach. The simulation called for a 10-day latency period, followed by a 6-day distraction period. Stress (with the von Mises stress score), strain, and displacement (x-axis of the coordinate system) of the crown, root, and bone were all analyzed. The conclusion drawn from this study was that changing the design of the osteotomy can affect the mechanical response of the alveolar structures. The authors found that the parasymphyseal step osteotomy using the hybrid-borne force system produced the most significant expansions of the alveolar bone, basal bone, and teeth. This was most likely because the appliance was supported by the teeth and bone, and the osteotomized alveolar bone was supported by the basal bone. The authors recognized the need for further clinical studies to address potential issues such as stability, effects on the temporomandibular joint, and physiologic bone response to such surgical procedures in the mandible. Reviewed by Michael Capogna Facial esthetics is often considered one of the most important outcomes of orthodontic treatment. In this study, photographs were taken of 63 full Class II Division 1 patients and evaluated for attractiveness and age by 83 laypeople and 76 orthodontists. The patients were divided into 3 groups including nonextraction, 2 premolar extraction, and 4 premolar extraction. These patients were compared by age, treatment time, sex, and posttreatment outcomes 15 to 18 years later. Dolphin software was used to evaluate soft tissue profiles. The authors found no statistically significant difference in facial attractiveness or age between 2 premolar extraction, 4 premolar extraction, and nonextraction patients. Interestingly, they also found no significant correlation between any soft tissue cephalometric variable and facial attractiveness. Reviewed by Matthew Cassera The aim of this study was to analyze the stress distributions of cylindrical and tapered miniscrews placed at different angles on roots, periodontial ligaments, and surrounding bones using a 3-dimensional finite element analysis. With a computer-generated maxilla model with first premolar extraction sites, 2 types of miniscrews (cylindrical and tapered) were inserted at 30°, 60°, and 90° angles with respect to the bone surface. The miniscrews were inserted in the interradicular space between the maxillary second premolar and first molar. A horizontal force of 2 N of pulling mesially parallel to the occlusal plane was applied to the miniscrew simulating the orthodontic force used for en-mass retraction of anterior teeth. The von Mises stresses were then measured in the roots and periodontial ligaments of the maxillary second premolars, first molars, cortical bone, and cancellous bone during miniscrew insertion and after orthodontic force loading. The analyses showed that the stresses were primarily absorbed by the cortical bone both in insertion and after force application. Little stress was transmitted to the root, periodontial ligament, and cancellous bone. Based on the findings, it is recommended that miniscrews, regardless of type, be placed perpendicular to the bone surface, to maximize anchorage and minimize stress levels in the surrounding bone. Additionally, cylindrical miniscrews are recommended because they resulted in lower stresses in the surrounding bone than do tapered miniscrews during insertion, but no difference was seen after force application between the 2 groups. Because the study used 3-dimensional finite element analysis, several limitations should be considered when interpreting the data. Further research is needed to determine the effects of changes with cortical bone thickness and cancellous bone density. Reviewed by Issac Chung The use of pendulum and distal jet appliances and superelastic nickel-titanium wires has become popular for correcting dental Class II malocclusions. However, they have 2 main negative effects: (1) anchorage loss in reaction to molar distalization, and (2) the high risk of relapse to the Class II molar relationship while retracting the anterior teeth. To increase anchorage resistance and prevent undesirable side effects on anchoring teeth, the use of temporary skeletal anchorage devices was introduced. However, comparisons between interradicular (MGBM System [MGBM]) and paramedian (Distal Screw [DS]) miniscrew insertion techniques are still lacking. The aim of this study was to compare the 2 techniques in dental Class II patients. Pretreatment and postdistalization lateral cephalograms of 53 white patients were retrospectively obtained. They were divided into 2 groups: 29 patients (16 boys, 13 girls) with a mean age of 12.3 ± 1.5 years were treated with the MGBM, and 24 patients (11 boys, 13 girls) with a mean age of 11.3 ± 1.2 years were treated with the DS appliance. The MGBM resulted in less distalization time (MDBM, 6 ± 2 months vs DS, 9 ± 2 months) and greater amounts of molar distalization (MGBM, −5.5 mm vs DS, −3.2 mm). However, the main difference between them was represented by the premolar movement. MGBM could not provide absolute anchorage because of the low rigidity of the metallic ligatures, so that the premolar showed a small mesial movement of 1.4 mm (DS, 2.2 mm distal movement) and the incisors showed a slight proclination of 1.6° (DS, no substantial changes) after distalization. There were no significant vertical changes in either group. Reviewed by Kensuke Matsumoto Orthopedic treatment for Class III skeletal problems is aimed at reducing or redirecting mandibular growth or enhancing maxillary growth. The primary aim of this study was to prospectively evaluate whether early Class III protraction facemask treatment reduces the need for orthognathic surgery. The secondary aims were to evaluate long-term skeletal and occlusal changes, self-esteem, and the esthetic impact of malocclusion. This study was a multi-center 2-arm parallel, randomized controlled trial. Patients were randomly allocated, stratified for sex, and grouped into an early Class III protraction facemask group (n = 35) and a control/no treatment group (n = 38). The primary outcome, need for orthognathic surgery, was assessed by panel consensus. The secondary outcomes were changes in skeletal pattern, overjet, Peer Assessment Rating, self-esteem, and the oral esthetic impact of malocclusion. The data were compared between the baseline and the 6-year follow-up. The main finding was that 66% of the patients in the control group were considered to need orthognathic surgery compared with 36% of the patients in the protraction facemask group. Therefore, it was concluded that early Class III protraction facemask treatment reduces the need for orthognathic surgery from two-thirds to one-third. Early protraction facemask treatment-related improvements in the SNA, SNB, and ANB angles were not maintained at the 6-year follow-ups. However, there were statistically significant long-term clockwise rotations in the maxilla and the mandible in the protraction facemask group. Early protraction facemask treatment does not seem to confer a clinically significant psychosocial benefit. The limitation of this study was that further Class III growth is likely to occur in both groups after the age of 15 years when the data were collected. Since the long-term follow-up data showed no skeletal effect in the protraction facemask group, it is suggested for the future that more skeletal methods of Class III protraction, such as bone-anchored maxillary protraction, may be more effective in the long term. Reviewed by Samaneh Mojarrad The periodontal ligament (PDL) undergoes remodeling during orthodontic tooth movement and relapse. PDL collagen degrades at the pressure side when orthodontic force is applied, whereas collagen recovers its original structure when the force is withdrawn. PDL progenitor cells (PDLSCs) are the main stem cell population in the PDL with the potential to differentiate into and provide multiple cell types to maintain PDL tissue homeostasis and repair. The authors aimed to investigate the role of PDLSCs in PDL remodeling during orthodontic tooth movement and the ensuing relapse. Twenty-eight rats were subjected to orthodontic force (60 cN) delivered by coil springs ligated between the first molars and incisors for 14 days. Then, the rats were randomly divided into 4 groups (n = 7) with different durations of relapse (0, 1, 5, and 14 days). In each group, the relapse ratio was measured and correlated with histologic findings. Histochemical staining showed compressive force-induced degradation of PDL collagen, which was gradually recovered during the relapse period. Correspondingly, PDLSCs exhibited repressed collagen expression in response to orthodontic force while they regained collagen expression after force withdrawal. These findings were further corroborated by in-vitro experiments where cultured human PDLSCs showed the same collagen expression pattern upon and after mechanical force; this was coincident with TGF-β expression levels. Furthermore, force withdrawal-induced recovery of collagen expression in PDLSCs was partially inhibited by TGF-β receptor inhibitor, indicating that the collagen expression in PDLSCs could be regulated by the TGF-β signaling pathway. Interestingly, local administration of TGF-β receptor inhibitor around the moved rat molars during early relapse militated against PDL collagen recovery and mitigated early relapse. The authors concluded that PDLSCs assume a prominent role in PDL collagen recovery via TGF-β signaling during early relapse, thus contributing to PDL homeostasis. This study at least in part unravels the mechanism underlying orthodontic relapse and provides an insight into PDL homeostasis. However, the role of other PDL cells and the interplay between them to maintain PDL structure and function still need to be elucidated. Reviewed by John Park Juvenile idiopathic arthritis (JIA) is inflammation in the joints of children and adolescents younger than 16 years old with no apparent cause. When the temporomandibular joint (TMJ) is involved, it can lead to mandibular growth deviations, as well as stunted development of posterior face height, malocclusions with anterior open bite, and altered muscular function. Treatment for patients with JIA and TMJ arthritis includes both medical and orthopedic interventions. Medications are used to control inflammation, whereas orthopedic treatment with distraction splints are used to encourage normal growth and development of the mandible and dentoalveolar complex. The aim of this study was to “evaluate condylar morphology and mandibular growth changes using 3D reconstructions and superimpositions of the mandible on CBCT scans of patients with JIA and unilateral TMJ affection treated with a distraction splint.” This was a retrospective longitudinal study that compared condylar morphology of 16 patients with JIA with a control group of 11. The inclusion criteria for the JIA group were diagnosis of JIA, unilateral radiographically diagnosed deformed condyle, more than 2 activations of the functional orthopedic appliance, and CBCT scans taken before and 2 years after treatment. The inclusion criteria for the control group were absence of TMJ disorders, no treatment with functional appliances, and CBCT scans taken similarly to the affected group. The study and control groups had mean ages of 11.9 years (range, 6.6-15.6 years) and 11.7 years (range, 7.7-14.5 years), respectively. There were 7 boys and 9 girls in the study group and 3 boys and 8 girls in the control group. The CBCT images were acquired, and then the mandibles segmented and reconstructed using Mimics software. These 3D reconstructed mandibles were then superimposed using point-to- point registrations for 9 anatomic landmarks, including regions of the mandibular foramen, the cortical plate of the symphysis, the mental foramen, and the mental protuberances. Linear and volumetric changes to the condyles were measured, and condylar growth directions were calculated. The results showed that smaller condylar volume, distal condylar displacement, vertical displacement, and ramus length all contribute to asymmetry in patients with JIA; both condyles showed more distal growth in affected patients, and the affected side showed the smallest displacement and more medial growth of gonion. The authors concluded that functional treatment for patients with JIA and unilateral TMJ arthritis is an effective tool for allowing condylar adaptation and modeling. As well, they highlighted the importance of using 3D technology to analyze the superimposition of condyles from many different viewpoints. Reviewed by Robert Vicelli Whether there are associations among temporomandibular disorders (TMDs), orthognathic surgery, and condylar morphologic changes has been an area of interest investigated through various studies with conflicting results. In this article, the authors aimed to determine the association between morphologic condylar changes and TMDs in patients who underwent orthognathic surgery. It was a retrospective study involving 89 patients who had 3 of the most common types of orthognathic surgical procedures: LeFort I, bilateral sagittal split osteotomy, or both. The variables reviewed in this study were age, sex, type of dentofacial deformity, type of surgical procedure, TMDs and the Helkimo index, and radiologic measurements on panoramic radiographs using specific computational methods, such as condylar height, area, and perimeter. The results indicated that 73% of the patients had morphologic condylar changes, and the predictors of postoperative TMDs used in this study were decreases in condylar perimeter and area and disk displacement. The authors concluded that postoperative condylar morphologic changes in patients with orthognathia are significantly associated with postoperative TMDs, as well as with TMD severity. Also, preoperative TMDs were significantly associated with postoperative condylar morphologic changes. It would be interesting to see this retrospective study repeated with a larger sample size, with the analysis stratified based on different types of orthognathic surgery. Also, it would be valuable to follow up on condylar morphologic changes over time to have multiple times of reference to see whether the changes vary over time. Reviewed by Brianna Yang

Ceramic brackets and low friction : A possible synergy in patients requiring multiple MRI scanning.

To investigate any advantages of low friction biomechanics in orthodontic patients with fixed appliances without producing metal artifacts during magnetic resonance imaging (MRI). Frictional resistance generated by bracket-wire-ligature systems was analyzed via an experimental model that reproduced upper canine misalignment. Each sample was tested 10 consecutive times in a dry state; a total of 160 tests were carried out. We documented the frictional forces generated by a 0.012- and 0.014-inch superelastic nickel-titanium wire (SENT) with ceramic self-ligating brackets (SLB) with metal insert and ceramic monocrystalline brackets with nonconventional elastic ligatures (NCEL) in conjunction with various degrees of canine misalignment (1.5, 3.0, 4.5, and 6.0mm). Comparisons between the frictional forces released by the two different bracket-wire-ligature systems were made by conducting 3-way analysis of variance (ANOVA) with Tukey HSD pairwise test (P<0.005). We observed no clinically relevant difference between the frictional forces released by ceramic SLB and ceramic brackets in conjunction with a 0.012- and 0.014-inch SENT. Statistically significant differences were apparent with a 0.012-inch SENT at 4.5 and 6.0mm of canine misalignment, where the SLB revealed higher frictional forces. Ceramic brackets with NCEL revealed frictional forces similar to those generated in conjunction with ceramic SLB, thereby helping to avoid metal artifacts in case of expected necessary MRI during orthodontic treatment with fixed appliances.

Force deflection comparison of various heat-activated superelastic nickel-titanium archwires: An in-vitro study

Objectives: To evaluate the load - deflections, compare superelasticity ratios and evaluate mechanical hysteresis for 5 commercial types of heat-activated superelastic orthodontic arch wires in a customized design of 3-point bend test maintained at a temperature of 37°C. Materials and Methods: The 3-point bending test was executed and provided values for the modulus of elasticity in bending, flexural stress, flexural strain and the flexural stress-strain response of the material. Results: Austenitic nickel-titanium (A-NiTi) exhibited constant forces but over a lesser range of deflection whereas heat-activated, superelastic nickel-titanium (NiTi) wires exhibited lower forces over a larger range of deflection. Conclusions: Heat-activated NiTi wires exhibited lower forces over a larger range of deflection, with the exception of one brand. In addition, they exhibit better superelastic ratios and a higher mechanical hysteresis than A-NiTi. A-NiTi exhibited constant forces but over a lesser range of deflection.

Residents' journal review

Orthopedic prevention of asymmetry in unilateral temporomandibular joint arthritisStoustrup P, Küseler A, Kristensen KD, Herlin T, Pedersen TK. Orthopaedic splint treatment can reduce mandibular asymmetry caused by unilateral temporomandibular involvement in juvenile idiopathic arthritis. Eur J Orthod 2013;35:191-8Between 20% and 70% of patients with juvenile idiopathic arthritis demonstrate involvement of the temporomandibular joint. Among these, 40% to 50% experience unilateral temporomandibular joint involvement. The purpose of this study was to evaluate the effects of an orthopedic splint in mitigating the effects of unilateral juvenile idiopathic arthritis on mandibular growth and dentoalvelolar development. Twenty-two patients were treated with a distraction splint. This appliance is an acrylic splint that covers the occlusal surfaces of the mandibular teeth; the posterior height on the arthritic side is gradually increased to prevent eruption of the mandibular first molar while allowing eruption of the maxillary first molar. The treatment objectives were to correct the cant of the occlusal plane, gradually unload the joint, and guide the mandible into the normal anterior rotational growth pattern. Condylar height, ramus height, and total mandibular vertical height were measured on panoramic views constructed from cone-beam computed tomography images before and after treatment. A ratio between the affected and unaffected sides was calculated for each variable of interest to measure mandibular asymmetry. The results showed that the distraction splint decreased mandibular asymmetry for ramus height and total vertical mandibular height. Mandibular growth rates on the affected and unaffected sides were comparable in most patients. Although the unaffected side was used as a control, both the possible subsequent juvenile idiopathic arthritis of the normal temporomandibular joint and the effects of appliance therapy on dentoalveolar development on this side make the suitability of this internal control questionable. Because no control group was used, it is difficult to conclude whether or which of the outcomes were due to treatment. Nevertheless, the findings on the possible effects of this splint therapy and future studies with appropriate controls could provide valuable information on the efficacy of splint therapy in the management of this complex disorder.Reviewed by Mona BajestanNickel-free titanium-niobium material for orthodontic wiresArciniegas M, Manero JM, Espinar E, Llamas JM, Barrera JM, Gil FJ. New Ni-free superelastic alloy for orthodontic applications. Mater Sci Eng C Mater Biol Appl 2013;33:3325-8The low magnitude and continuous forces generated by superelastic nickel-titanium wires are optimal for orthodontic tooth movement. However, nickel-containing wires can cause contact dermatitis in patients with a nickel allergy. The authors of this study evaluated the superelasticity, corrosion resistance, and cytotoxicity of Ti19.1Nb8.8Zr, a new nickel-free titanium alloy that might be suitable for orthodontic applications. Phase transition and superelasticity were measured by calorimetry and by subjecting wire specimens to 150 load-unload cycles in artificial saliva at 37°C. Corrosion of the titanium alloy with specific measurements of open circuit potential, corrosion potential, and corrosion current density were compared with 6 commonly used nickel-titanium orthodontic archwires. The cytotoxicity of the titanium alloy was measured by immersing it and the controls in DMEM media at 37°C, followed by culturing of MG63 cells in this media and counting live cells. The results of the calorimetry tests showed reversible austenitic-martensitic phase transformations with martensite start-finish at 45°C to 14.8°C, and austenite start-finish at 46°C to 87°C. Repeated load and unload cycles indicated typical superelastic behavior in the titanium alloy with a mechanical phase transformation plateau from 0.5 to 8 mm of deflection. After 150 cycles, there was approximately 0.2 mm of residual elongation of the wire after deflection. The nickel-free archwire had the best resistance to corrosion among all the wires investigated. The titanium-alloy wires showed favorable cytotoxicity values, with 100% of the cells remaining viable at 72 hours; this was not significantly different relative to the controls. The nickel-free Ti19.1Nb8.8Zr alloy demonstrates superelastic behavior, better corrosion resistance compared with common nickel-titanium wires, and excellent biocompatibility. Since the authors used a 2.5-mm diameter wire, which is substantially larger than those used in orthodontic practices, further investigations are recommended with wire sizes more typically used for orthodontic treatment to derive clinically relevant information.Reviewed by Adam DonnellAllergic rhinitis and malocclusionLuzzi V, Ierardo G, Viscogliosi A, Fabbrizi M, Consoli G, Vozza I, et al. Allergic rhinitis as a possible risk factor for malocclusion: a case-control study in children. Int J Paediatr Dent 2013;23:274-8Chronic mouth breathing caused by airway obstruction has been theorized to produce postural changes that lead to dental or skeletal malocclusions. The authors of this case-control study recruited 275 Italian primary schoolchildren (ages, 5-9 years) to investigate the possible link between allergic rhinitis and malocclusion. The study group consisted of 125 children with malocclusion; they were compared with a control group of 150 children without malocclusion using clinical examinations, lateral cephalometric radiographs, and dental casts. Mouth breathing was determined based on lip incompetence, dry lips, and fogging on the lower side of a double-faced mirror. Airway obstruction from allergic rhinitis was determined from a questionnaire completed by the children's parents. The authors found both the prevalence of allergic rhinitis (59% vs 13%) and the severity of allergic rhinitis (multiple allergens, perennial rhinitis, and under pharmacologic treatment vs single allergen, seasonal rhinitis, and minimal pharmacologic treatment) to be significantly greater in the malocclusion group. The investigators also found that allergic rhinitis produced a slightly greater than 3-fold increased risk of dentoskeletal alteration, a slightly less than 3-fold increased risk of posterior crossbite, and a 2-fold greater risk of increased overjet. There was no significant difference in anterior open bite between the 2 groups. Based on their results, the authors concluded that allergic rhinitis should be considered a risk factor for developing a malocclusion and that orthodontic examination of children affected by allergic rhinitis is recommended for early intervention in the development of rhinitis-associated malocclusions. Their conclusions could have been further strengthened with additional information on the timing of the onset of allergic rhinitis and the frequency of pharmacologic treatment in the mouth-breathing groups.Reviewed by John DuRusselWidth and length of enamel microcracks after debondingDumbryte I, Linkeviciene L, Malinauskas M, Linkevicius T, Peciuliene V, Tikuisis K. Evaluation of enamel micro-cracks characteristics after removal of metal brackets in adult patients. Eur J Orthod 2013;35:317-22Enamel microcracks have been shown to predispose teeth to staining or plaque accumulation. As more adults—who are more prone to enamel microcracks—seek orthodontic treatment, procedures that contribute to this process take on increased clinical relevance. The purpose of this in-vitro study was to compare the location, length, and width of enamel microcracks in adult teeth before bonding and after the removal of metal brackets. Forty-five extracted teeth with intact buccal enamel were collected from middle-aged adults with no previous orthodontic treatment. The teeth were analyzed using scanning electron microscopy and divided into 3 groups: (1) teeth with existing enamel microcracks, (2) teeth without enamel microcracks, and (3) an unbonded control group used to study the effects of dehydration. After bonding, followed by bracket and residual adhesive removal, scanning electron microscopy was used to reevaluate the enamel surfaces of each tooth. The results showed that 40% of the bonded teeth developed new microcracks. Also, although there was no significant increase in the mean length of the microcracks, there was a significant increase in their mean width in the cervical third of the crown. The limitations of the study include the fact that debonding forces were not measured or standardized, and that the effects of debonding in vitro might not fully simulate the effects of debonding in a patient. Despite these limitations, the results reaffirm the importance for clinicians to pay special attention during debonding procedures, especially in the cervical third of the crown. It would be interesting to compare these results with those of a similar study of ceramic brackets to give patients more information regarding their treatment options.Reviewed by Carmen GarciaCone-beam computed tomography evaluation of alveolar bone after rapid maxillary expansionBaysal A, Uysal T, Veli I, Ozer T, Karadede I, Hekimoglu S. Evaluation of alveolar bone loss following rapid maxillary expansion using cone-beam computed tomography. Korean J Orthod 2013;43:83-95Rapid maxillary expansion (RME) is a common orthodontic procedure used for correction of maxillary transverse discrepancies and arch-length deficiencies. The authors of this study used cone-beam computed tomography to evaluate the effects of RME on cortical bone thickness, alveolar bone height, and the incidence of dehiscence and fenestration after a 6-month follow-up period. Cone-beam computed tomography images were taken of 20 subjects (9 boys: mean age, 13.97 ± 1.17 years; 11 girls: mean age, 13.53 ± 2.12 years) before and after RME. Ten additional subjects had cone-beam computed tomography images taken at a 6-month follow up appointment. Buccal alveolar height, buccal cortical bone thickness, and palatal cortical bone thickness of the maxillary canines, first and second premolars, and first molars were analyzed. Decreases in the buccal cortical bone thickness and palatal cortical bone thickness were observed for the investigated teeth after RME and at the 6-month follow up. Vertical alveolar height measured as buccal alveolar height decreased immediately after the expansion period and remained unchanged at the 6-month follow up. In general, the incidence of dehiscence was greater after treatment and at the 6-month follow-up than before RME. Since the thickness and the height of the buccal alveolar bone decreased and dehiscence formation increased, the authors concluded that RME might have detrimental effects on the supporting alveolar bone. Although the study provides important information of possible consequences of RME on the integrity of alveolar bone because measurements in 3-dimensional–rendered projections are not accurate and partial volume averaging artifacts and tooth rotations were not taken into account, caution should be exercised in interpreting the findings of this study.Reviewed by Elliot SapersteinBucally displaced canines and facial characteristicsMucedero M, Ricchiuti MR, Cozza P, Baccetti T. Prevalence rate and dentoskeletal features associated with buccally displaced maxillary canines. Eur J Orthod 2013;35:305-9Buccally displaced canines (BDCs) have long been related to insufficient arch length in the maxilla, but they have not been correlated to measurements in the skeletal complex. The authors of this study analyzed the prevalence and distribution of BDCs in a large untreated population and investigated the association of BDCs with sagittal, vertical, and transverse skeletal relationships, as well as maxillary dental crowding. The parent sample included 1852 subjects from the Department of Orthodontics of the University of Rome “Tor Vergata.” The sample was divided randomly into 2 groups. The control group, comprising the first 252 subjects, was used for calculation of the reference prevalence rates for the examined parameters. The experimental group comprised the remaining 1600 subjects. Of this group, 49 subjects had BDCs. The results showed a prevalence rate of maxillary BDCs of 3.06% in the experimental sample, with a unilateral-to-bilateral ratio of 33:16, and a male-to-female ratio of 1:1. The group with BDCs had a significantly higher prevalence of hyperdivergent subjects, a significantly smaller average maxillary intercanine width (−3.82 mm), and greater dental crowding (4.15 mm) than did the control group. The study suggests a significant association of BDCs with reduced maxillary intercanine width, maxillary crowding, and facial hyperdivergence. These characteristics can be used as indicators of the risk for developing maxillary BDCs. The authors also suggested that, as opposed to palatally displaced canines, BDCs are not predominantly under genetic control, but local dentoskeletal features act as predisposing environmental factors for BDCs upon eruption. This was generally a well-performed study that adds clarity of associated findings with maxillary BDCs. However, caution should be exercised in the investigators' attribution of maxillary BDCs to nongenetic causes.Reviewed by Brad StieperTorque expression in lingual orthodonticsSifakakis I, Pandis N, Makou M, Eliades T, Katsaros C, Bourauel C. A comparative assessment of torque generated by lingual and conventional brackets. Eur J Orthod 2013;35:375-80Among other variables, orthodontic torque expression is controlled by the dimensions of the wire, bracket placement, and the amount of third-order activation placed into the wire. The highly variable lingual tooth morphology and the different relative positions to the center of resistance between lingual and labial brackets might contribute to difficulties in lingual bracket torque control. Despite these differences, torque expression in lingual orthodontics has not been thoroughly studied. The authors of this study compared the torque expression in 4 bracket systems (0.018-in slot—Incognit lingual brackets (3M Unitek, Monrovia, Calif), STb lingual brackets (Light Lingual System; Ormco, Orange, Calif), In-Ovation L lingual brackets (DENTSPLY GAC, Islandia, NY), and conventional stainless steel brackets (Gemini Twin; 3M Unitek)—on 1 maxillary central incisor in a typodont). An orthodontic simulation system was used to sense the force-torque vectors 3 dimensionally. The greatest torque expression was observed in the Incognito and STb lingual brackets. The lowest amount of torque was found in the In-Ovation lingual and conventional labial brackets. The authors concluded that the moment of the couple produced from a rectangular wire depends more on the mode of ligation: ie, self-ligation vs conventional ligation. The authors also found that torque for lingual brackets depends more on loading than on unloading moments. These results are based on moments generated on 1 typodont tooth, with a limited sample size, and the torque activation of the wire was performed by 1 investigator. Future research to determine torque expression in a segment of teeth in a more realistic environment with a larger sample size and calibrated wire activations will provide further useful and clinically relevant information.Reviewed by Vina Zinn Orthopedic prevention of asymmetry in unilateral temporomandibular joint arthritisStoustrup P, Küseler A, Kristensen KD, Herlin T, Pedersen TK. Orthopaedic splint treatment can reduce mandibular asymmetry caused by unilateral temporomandibular involvement in juvenile idiopathic arthritis. Eur J Orthod 2013;35:191-8Between 20% and 70% of patients with juvenile idiopathic arthritis demonstrate involvement of the temporomandibular joint. Among these, 40% to 50% experience unilateral temporomandibular joint involvement. The purpose of this study was to evaluate the effects of an orthopedic splint in mitigating the effects of unilateral juvenile idiopathic arthritis on mandibular growth and dentoalvelolar development. Twenty-two patients were treated with a distraction splint. This appliance is an acrylic splint that covers the occlusal surfaces of the mandibular teeth; the posterior height on the arthritic side is gradually increased to prevent eruption of the mandibular first molar while allowing eruption of the maxillary first molar. The treatment objectives were to correct the cant of the occlusal plane, gradually unload the joint, and guide the mandible into the normal anterior rotational growth pattern. Condylar height, ramus height, and total mandibular vertical height were measured on panoramic views constructed from cone-beam computed tomography images before and after treatment. A ratio between the affected and unaffected sides was calculated for each variable of interest to measure mandibular asymmetry. The results showed that the distraction splint decreased mandibular asymmetry for ramus height and total vertical mandibular height. Mandibular growth rates on the affected and unaffected sides were comparable in most patients. Although the unaffected side was used as a control, both the possible subsequent juvenile idiopathic arthritis of the normal temporomandibular joint and the effects of appliance therapy on dentoalveolar development on this side make the suitability of this internal control questionable. Because no control group was used, it is difficult to conclude whether or which of the outcomes were due to treatment. Nevertheless, the findings on the possible effects of this splint therapy and future studies with appropriate controls could provide valuable information on the efficacy of splint therapy in the management of this complex disorder.Reviewed by Mona Bajestan Stoustrup P, Küseler A, Kristensen KD, Herlin T, Pedersen TK. Orthopaedic splint treatment can reduce mandibular asymmetry caused by unilateral temporomandibular involvement in juvenile idiopathic arthritis. Eur J Orthod 2013;35:191-8Between 20% and 70% of patients with juvenile idiopathic arthritis demonstrate involvement of the temporomandibular joint. Among these, 40% to 50% experience unilateral temporomandibular joint involvement. The purpose of this study was to evaluate the effects of an orthopedic splint in mitigating the effects of unilateral juvenile idiopathic arthritis on mandibular growth and dentoalvelolar development. Twenty-two patients were treated with a distraction splint. This appliance is an acrylic splint that covers the occlusal surfaces of the mandibular teeth; the posterior height on the arthritic side is gradually increased to prevent eruption of the mandibular first molar while allowing eruption of the maxillary first molar. The treatment objectives were to correct the cant of the occlusal plane, gradually unload the joint, and guide the mandible into the normal anterior rotational growth pattern. Condylar height, ramus height, and total mandibular vertical height were measured on panoramic views constructed from cone-beam computed tomography images before and after treatment. A ratio between the affected and unaffected sides was calculated for each variable of interest to measure mandibular asymmetry. The results showed that the distraction splint decreased mandibular asymmetry for ramus height and total vertical mandibular height. Mandibular growth rates on the affected and unaffected sides were comparable in most patients. Although the unaffected side was used as a control, both the possible subsequent juvenile idiopathic arthritis of the normal temporomandibular joint and the effects of appliance therapy on dentoalveolar development on this side make the suitability of this internal control questionable. Because no control group was used, it is difficult to conclude whether or which of the outcomes were due to treatment. Nevertheless, the findings on the possible effects of this splint therapy and future studies with appropriate controls could provide valuable information on the efficacy of splint therapy in the management of this complex disorder.Reviewed by Mona Bajestan Between 20% and 70% of patients with juvenile idiopathic arthritis demonstrate involvement of the temporomandibular joint. Among these, 40% to 50% experience unilateral temporomandibular joint involvement. The purpose of this study was to evaluate the effects of an orthopedic splint in mitigating the effects of unilateral juvenile idiopathic arthritis on mandibular growth and dentoalvelolar development. Twenty-two patients were treated with a distraction splint. This appliance is an acrylic splint that covers the occlusal surfaces of the mandibular teeth; the posterior height on the arthritic side is gradually increased to prevent eruption of the mandibular first molar while allowing eruption of the maxillary first molar. The treatment objectives were to correct the cant of the occlusal plane, gradually unload the joint, and guide the mandible into the normal anterior rotational growth pattern. Condylar height, ramus height, and total mandibular vertical height were measured on panoramic views constructed from cone-beam computed tomography images before and after treatment. A ratio between the affected and unaffected sides was calculated for each variable of interest to measure mandibular asymmetry. The results showed that the distraction splint decreased mandibular asymmetry for ramus height and total vertical mandibular height. Mandibular growth rates on the affected and unaffected sides were comparable in most patients. Although the unaffected side was used as a control, both the possible subsequent juvenile idiopathic arthritis of the normal temporomandibular joint and the effects of appliance therapy on dentoalveolar development on this side make the suitability of this internal control questionable. Because no control group was used, it is difficult to conclude whether or which of the outcomes were due to treatment. Nevertheless, the findings on the possible effects of this splint therapy and future studies with appropriate controls could provide valuable information on the efficacy of splint therapy in the management of this complex disorder. Reviewed by Mona Bajestan Nickel-free titanium-niobium material for orthodontic wiresArciniegas M, Manero JM, Espinar E, Llamas JM, Barrera JM, Gil FJ. New Ni-free superelastic alloy for orthodontic applications. Mater Sci Eng C Mater Biol Appl 2013;33:3325-8The low magnitude and continuous forces generated by superelastic nickel-titanium wires are optimal for orthodontic tooth movement. However, nickel-containing wires can cause contact dermatitis in patients with a nickel allergy. The authors of this study evaluated the superelasticity, corrosion resistance, and cytotoxicity of Ti19.1Nb8.8Zr, a new nickel-free titanium alloy that might be suitable for orthodontic applications. Phase transition and superelasticity were measured by calorimetry and by subjecting wire specimens to 150 load-unload cycles in artificial saliva at 37°C. Corrosion of the titanium alloy with specific measurements of open circuit potential, corrosion potential, and corrosion current density were compared with 6 commonly used nickel-titanium orthodontic archwires. The cytotoxicity of the titanium alloy was measured by immersing it and the controls in DMEM media at 37°C, followed by culturing of MG63 cells in this media and counting live cells. The results of the calorimetry tests showed reversible austenitic-martensitic phase transformations with martensite start-finish at 45°C to 14.8°C, and austenite start-finish at 46°C to 87°C. Repeated load and unload cycles indicated typical superelastic behavior in the titanium alloy with a mechanical phase transformation plateau from 0.5 to 8 mm of deflection. After 150 cycles, there was approximately 0.2 mm of residual elongation of the wire after deflection. The nickel-free archwire had the best resistance to corrosion among all the wires investigated. The titanium-alloy wires showed favorable cytotoxicity values, with 100% of the cells remaining viable at 72 hours; this was not significantly different relative to the controls. The nickel-free Ti19.1Nb8.8Zr alloy demonstrates superelastic behavior, better corrosion resistance compared with common nickel-titanium wires, and excellent biocompatibility. Since the authors used a 2.5-mm diameter wire, which is substantially larger than those used in orthodontic practices, further investigations are recommended with wire sizes more typically used for orthodontic treatment to derive clinically relevant information.Reviewed by Adam Donnell Arciniegas M, Manero JM, Espinar E, Llamas JM, Barrera JM, Gil FJ. New Ni-free superelastic alloy for orthodontic applications. Mater Sci Eng C Mater Biol Appl 2013;33:3325-8The low magnitude and continuous forces generated by superelastic nickel-titanium wires are optimal for orthodontic tooth movement. However, nickel-containing wires can cause contact dermatitis in patients with a nickel allergy. The authors of this study evaluated the superelasticity, corrosion resistance, and cytotoxicity of Ti19.1Nb8.8Zr, a new nickel-free titanium alloy that might be suitable for orthodontic applications. Phase transition and superelasticity were measured by calorimetry and by subjecting wire specimens to 150 load-unload cycles in artificial saliva at 37°C. Corrosion of the titanium alloy with specific measurements of open circuit potential, corrosion potential, and corrosion current density were compared with 6 commonly used nickel-titanium orthodontic archwires. The cytotoxicity of the titanium alloy was measured by immersing it and the controls in DMEM media at 37°C, followed by culturing of MG63 cells in this media and counting live cells. The results of the calorimetry tests showed reversible austenitic-martensitic phase transformations with martensite start-finish at 45°C to 14.8°C, and austenite start-finish at 46°C to 87°C. Repeated load and unload cycles indicated typical superelastic behavior in the titanium alloy with a mechanical phase transformation plateau from 0.5 to 8 mm of deflection. After 150 cycles, there was approximately 0.2 mm of residual elongation of the wire after deflection. The nickel-free archwire had the best resistance to corrosion among all the wires investigated. The titanium-alloy wires showed favorable cytotoxicity values, with 100% of the cells remaining viable at 72 hours; this was not significantly different relative to the controls. The nickel-free Ti19.1Nb8.8Zr alloy demonstrates superelastic behavior, better corrosion resistance compared with common nickel-titanium wires, and excellent biocompatibility. Since the authors used a 2.5-mm diameter wire, which is substantially larger than those used in orthodontic practices, further investigations are recommended with wire sizes more typically used for orthodontic treatment to derive clinically relevant information.Reviewed by Adam Donnell The low magnitude and continuous forces generated by superelastic nickel-titanium wires are optimal for orthodontic tooth movement. However, nickel-containing wires can cause contact dermatitis in patients with a nickel allergy. The authors of this study evaluated the superelasticity, corrosion resistance, and cytotoxicity of Ti19.1Nb8.8Zr, a new nickel-free titanium alloy that might be suitable for orthodontic applications. Phase transition and superelasticity were measured by calorimetry and by subjecting wire specimens to 150 load-unload cycles in artificial saliva at 37°C. Corrosion of the titanium alloy with specific measurements of open circuit potential, corrosion potential, and corrosion current density were compared with 6 commonly used nickel-titanium orthodontic archwires. The cytotoxicity of the titanium alloy was measured by immersing it and the controls in DMEM media at 37°C, followed by culturing of MG63 cells in this media and counting live cells. The results of the calorimetry tests showed reversible austenitic-martensitic phase transformations with martensite start-finish at 45°C to 14.8°C, and austenite start-finish at 46°C to 87°C. Repeated load and unload cycles indicated typical superelastic behavior in the titanium alloy with a mechanical phase transformation plateau from 0.5 to 8 mm of deflection. After 150 cycles, there was approximately 0.2 mm of residual elongation of the wire after deflection. The nickel-free archwire had the best resistance to corrosion among all the wires investigated. The titanium-alloy wires showed favorable cytotoxicity values, with 100% of the cells remaining viable at 72 hours; this was not significantly different relative to the controls. The nickel-free Ti19.1Nb8.8Zr alloy demonstrates superelastic behavior, better corrosion resistance compared with common nickel-titanium wires, and excellent biocompatibility. Since the authors used a 2.5-mm diameter wire, which is substantially larger than those used in orthodontic practices, further investigations are recommended with wire sizes more typically used for orthodontic treatment to derive clinically relevant information. Reviewed by Adam Donnell Allergic rhinitis and malocclusionLuzzi V, Ierardo G, Viscogliosi A, Fabbrizi M, Consoli G, Vozza I, et al. Allergic rhinitis as a possible risk factor for malocclusion: a case-control study in children. Int J Paediatr Dent 2013;23:274-8Chronic mouth breathing caused by airway obstruction has been theorized to produce postural changes that lead to dental or skeletal malocclusions. The authors of this case-control study recruited 275 Italian primary schoolchildren (ages, 5-9 years) to investigate the possible link between allergic rhinitis and malocclusion. The study group consisted of 125 children with malocclusion; they were compared with a control group of 150 children without malocclusion using

Frictional resistance in monocrystalline ceramic brackets with conventional and nonconventional elastomeric ligatures

BackgroundThe objective of this study was to compare the frictional forces generated by three types of monocrystalline ceramic brackets coupled with conventional elastomeric ligatures (CEL) and nonconventional elastomeric ligatures (NCEL) during the alignment of apically displaced teeth at the maxillary arch.MethodsAll tests (a total of 480 tests) were carried out in a dry state on a universal testing machine with a testing model consisting of three 0.022-in. monocrystalline ceramic preadjusted brackets (from the maxillary right second premolar through the right central incisor). The canine bracket was bonded to a sliding bar that allowed for different vertical positions. The frictional forces generated by a 0.012- and 0.014-in. superelastic nickel titanium wire (SENT) with conventional and nonconventional ligatures at various amounts of canine misalignment (1.5, 3.0, 4.5, and 6.0 mm) were recorded. Comparisons between the different types of bracket-wire-ligature systems were carried out by means of analysis of variance on ranks with Tukey's post hoc test (P < 0.05).ResultsNo significant differences were assessed among the three types of monocrystalline brackets with NCEL when coupled with 0.012-in. SENT. Radiance brackets with NCEL coupled with 0.014-in. SENT showed significantly greater frictional force than Inspire Ice brackets and Pure brackets with NCEL. A significantly greater amount of frictional force was generated with CEL when compared with NCEL for all the tested variables, with the exception of the Pure brackets with 0.012-in. SENT at 1.5 and 3.0 mm of canine misalignment where similar frictional forces were found.ConclusionsNonconventional elastomeric ligatures are able to reduce friction in monocrystalline ceramic brackets.

A Simple Therapeutic Approach to Pincer Nail Deformity Using a Memory Alloy: Measurement of Response

Pincer nail deformity (PND) is a dystrophy characterized by transverse overcurvature of the nail plate that may cause intractable pain and decrease the quality of life of patients. To evaluated the efficacy of a superelastic nickel-titanium (SE NiTi) wire for the treatment of PND using transverse curvature improvement and subjective assessment of pain relief during and after the treatment. SE NiTi wire was implanted over the distal tip of the nail for the treatment of PND in 43 patients (28 female, 15 male), with a total of 73 digits receiving treatment. Evaluations of improvement included measuring changes in transverse curvature of the nail and subjective assessment of pain relief throughout the follow-up period. In all patients, treatment of the pincer nail with implantation of SE NiTi wire achieved satisfactory results. Significant improvement (p<.05) of the transverse overcurvature of the nail was seen in all patients at 2months, and relief of pain was determined in 100% of cases throughout our follow-up period. This simple SE NiTi wire insertion method is noninvasive and inexpensive, leaves no cosmetic disfigurement, and leads to excellent therapeutic results. Patients achieved great satisfaction. Thus, this technique should be considered the first line of treatment in the correction of mild to moderate PND.

Effect of Artificial Salvia on Force Values of Two Types of Nickel Titanium Ortho-dontic Arch Wires

Aims: To study the effect of artificial saliva and time interval on the amount of force values of nitinol and superelastic NiTi wires. Materials and Methods: Two types of orthodontic wires chosen for the study nitinol and superelastic NiTi wires of a guage of 0.016 inch in diameter (Dentaurum, Germany). Specimens of the wires were divided in to two groups ;the control group(dry condition) contained the wires as - received condition and experimental groups for the study of the force value of wires which subjected to artificial saliva for three time incubation periods (3 days, 7 days, 28 days) . At end of each incubation periods ,the wire specimens were tested for the effect of artificial saliva on force values of the wire. The measurement of force values of arch wires done with a universal tensile testing ma-chine ,the force values of specimens were evaluated with the help of three point bending test. The re-sults were subjected to the descriptive statistics and to the ANOVA and Duncan’s Multiple Range Analysis Tests to detect the amount of changes among these groups . Result: The findings of the present study showed that the control group of nitinol wires had the highest rate of force value with significant difference (P≤ 0.05) with experimental groups, while the experimental group after 28 days gave rise to the lowest one with significant difference (P≤ 0.05) from other groups. For the superelastic nickel titanium the result showed that the control group had the highest rate of force value while the experimental group after 28 days gave rise to the lowest one with significant difference (P≤ 0.05) from control and non significant difference (P> 0.05) with the experimental groups after 3 days and 7 days. Conclusion: The nitinol wires showed a continuous change in force values with increase time in ar-tificial saliva, so this required reactivating or changing the wire at a certain interval of use. While force values of the superelastic nickel titanium wires decreased after 3 days interval and remained constant after that .

Mechanical Properties of Controlled Memory and Superelastic Nickel-Titanium Wires Used in the Manufacture of Rotary Endodontic Instruments

IntroductionThe aim of this study was to investigate the structure and mechanical properties of newly developed controlled memory (CM) nickel-titanium wires used in the manufacture of rotary endodontic instruments. MethodsThe composition and the phase transformation behavior of both types of wires were examined by x-ray energy dispersive spectroscopy and differential scanning calorimetry, respectively. Conventional superelastic (SE) nickel-titanium wire was used as a control. The mechanical properties of the wires at selected temperatures (room temperature, 37°C, and 60°C) were evaluated with tensile, cyclic tensile, and cantilever bending tests by using an Instron 3365 universal testing machine. The data of austenitic transformation finishing temperature (Af) were analyzed statistically by using 1-way analysis of variance test at a significance level of P < .05. ResultsThe raw CM wires contained a nickel content of 50.7% ± 0.5% and possessed a relatively higher Af than SE wires (P < .05). The critical plateau stress and ultimate tensile strength of the CM wires were lower than they were for the SE wires, but the maximum strain before fracture of the CM wires (58.4% ± 7.5% to 84.7% ± 6.8%) was more than 3 times higher than it was for SE wires (16.7% ± 3.8% to 27.5% ± 5.4%). The maximum strain of the CM wires with a diameter of 1.22 mm tested at room temperature (23°C ± 2°C) was up to 84% ± 6.4%. CM wires were not SE at either room temperature or 37°C; however, they exhibited superelasticity when heated to 60°C. ConclusionsThe raw CM wires exhibited different phase transformation behavior and mechanical properties when compared with SE wires, attributing to the special heat treatment history of CM wires. This study suggested greater flexibility of endodontic instruments manufactured with CM wires than similar instruments made of conventional SE wires.

Orthodontic forces released by low-friction versus conventional systems during alignment of apically or buccally malposed teeth

The aim of the present study was to analyse the forces released by passive stainless steel self-ligating brackets (SLBs) and by a non-conventional elastomeric ligature-bracket system on conventional brackets ([slide ligatures on conventional brackets (SLCB)]) when compared with conventional elastomeric ligatures on conventional brackets (CLCB) during the alignment of apically or buccally malposed teeth in the maxillary arch. An experimental model consisting of five brackets was used to assess the forces released by the three different bracket-ligature systems with 0.012-inch super-elastic (SE) nickel-titanium (NiTi) wires in the presence of different amounts of apical or buccal canine misalignment of the canine (ranging from 1.5 to 6 mm). The forces released by each wire/bracket/ligature combination with the three different amounts of apical or buccal canine misalignment were tested 20 times. Comparisons between the different types of wire/bracket/ligature systems were carried out by means of analysis of variance on ranks with Dunnett's post hoc test (P < 0.05). No difference in the amount of force released in presence of a misalignment of 1.5 mm was recorded among the three systems. At 3 mm of apical misalignment a significantly greater amount of orthodontic force was released by SLB or SLCB when compared with CLCB, while no significant differences were found among the three systems at 3 mm of buccal canine displacement. When correction of a large amount of misalignment (6 mm) was attempted, a noticeable amount of force for alignment was still generated by the passive SLB and SLCB systems while no force was released in presence of CLCB.

Mechanical properties of coated superelastic archwires in conventional and self-ligating orthodontic brackets

Coated archwires have been introduced to improve esthetics during orthodontic treatment. Our aim was to investigate the mechanical properties of coated superelastic archwires compared with conventional superelastic archwires with conventional and self-ligating brackets. Four types of orthodontic archwires were investigated, 2 superelastic nickel-titanium and 2 coated Ultraesthetic archwires in 0.016-in and 0.018 x 0.025-in dimensions (all from G&H Wire, Greenwood, Ind). To achieve the same nominal size, the coated archwire is constructed from a smaller archwire that, when coated, reaches the nominal dimensions stated for the archwire. Conventional edgewise Orthos and Damon 2 self-ligating brackets (both from Ormco, Orange, Calif) were used with each wire. All specimens were tested in a universal testing machine in a 3-point bending test at a speed of 1 mm per minute and deflected for 2 mm. Loading and unloading forces were recorded and load-deflection curves plotted. Coated superelastic wires produced statistically significantly lower forces in loading and unloading when compared with the superelastic nickel-titanium wires at most archwire deflections (P <0.01). For nickel-titanium wires, loading values ranged from 189 to 1202 g, whereas the respective values for coated wires were 124 to 772 g. For all wires, an increase in size resulted in an increase in force. Interactions between wire type (coated or uncoated) and bracket type were observed. Ultraesthetic coated archwires produced lower force values in loading and unloading compared with uncoated wires of same nominal size. The Damon 2 self-ligating bracket system produced lower force values in loading and unloading. The lowest forces were generated by the combination of Ultraesthetic coated archwires and Damon 2 self-ligating brackets.

Metallurgical Characterization of a New Nickel-Titanium Wire for Rotary Endodontic Instruments

Introduction A novel thermomechanical processing procedure has been developed that yields a superelastic (SE) nickel-titanium (NiTi) wire (M-Wire) that laboratory testing shows has improved mechanical properties compared with conventional SE austenitic NiTi wires used for manufacture of rotary instruments. The objective of this study was to determine the origin of the improved mechanical properties. Method Specimens from 2 batches of M-Wire prepared under different processing conditions and from 1 batch of standard-processed SE wire for rotary instruments were examined by scanning transmission electron microscopy, temperature-modulated differential scanning calorimetry, micro–x-ray diffraction, and scanning electron microscopy with x-ray energy-dispersive spectrometric analyses. Results The processing for M-Wire yields a microstructure containing martensite, that the proportions of NiTi phases depend on processing conditions, and that the microstructure exhibits pronounced evidence of alloy strengthening. Conclusions The presence of Ti 2Ni precipitates in both microstructures indicates that M-Wire and the conventional SE wire for rotary instruments are titanium-rich.