Esthetics of Orthodontic Appliances: Objective Evaluation by Spectrophotometry vs Subjective Evaluation Using the Visual Analog Scale Method.

AIM AND OBJECTIVE: In this study, we quantified the color of brackets and archwire appliances for an objective evaluation and investigated its relationship with subjective esthetic evaluation. MATERIALS AND METHODS: Five types of commercially available brackets (ceramic brackets C1, C2, and C3; plastic brackets P1 and P2) and three types of archwires (coated nickel-titanium archwires W1, W2, and W3) were used. The reflectance (%) and color (lightness: L*, hue: a*, b*) of each sample were quantified using a spectrophotometer (n = 5). Fifteen combinations of brackets and archwires were used. The esthetic evaluation was performed using the visual analog scale (VAS) method, and responses were obtained from 30 laypersons and 15 orthodontists. The mean VAS score was calculated, and the relationship between the reflectance and color of the bracket and archwire was discussed. RESULTS: The reflectance and L* of the brackets showed significantly higher values for C3 and C1 than for the others and lower values for P1 and P2. The reflectance and L* of the archwire showed significant differences among all samples. There was a high positive correlation between the reflectance and L*. There were statistically significant positive correlations between the layperson and orthodontist groups, between the VAS score and reflectivity, and between VAS score and L*. CONCLUSION: Our results showed that as the lightness and reflectance of the brackets and archwires increased, the subjective evaluation concerning their esthetic value was higher. CLINICAL SIGNIFICANCE: It is extremely difficult to evaluate esthetics despite the fact that patients' demands for esthetics have been increasing in recent years. If a method for evaluating esthetics is established, it should help in the development and selection of esthetic devices. The results of this study will facilitate the development of future study designs.

Preferential Tumor Accumulation of Polyglycerol Functionalized Nanodiamond Conjugated with Cyanine Dye Leading to Near-Infrared Fluorescence In Vivo Tumor Imaging.

Preferential accumulation of nanoparticles in a tumor is realized commonly by combined effects of active and passive targeting. However, passive targeting based on an enhanced permeation and retention (EPR) effect is not sufficient to observe clear tumor fluorescence images in most of the in vivo experiments using tumor-bearing mice. Herein, polyglycerol-functionalized nanodiamonds (ND-PG) conjugated with cyanine dye (Cy7) are synthesized and it is found that the resulting ND-PG-Cy7 is preferentially accumulated in the tumor, giving clear fluorescence in in vivo and ex vivo fluorescence images. One of the plausible reasons is the longer in vivo blood circulation time of ND-PG-Cy7 (half-life: 58 h determined by the pharmacokinetic analysis) than that of other nanoparticles (half-life: <20 h in most of the previous reports). In a typical example, the fluorescence intensity of tumors increases due to continuous tumor accumulation of ND-PG-Cy7, even more than one week postinjection. This may be owing to the stealth effect of PG that was reported previously, avoiding recognition and excretion by reticuloendothelial cells, which are abundant in liver and spleen. In fact, the fluorescence intensities from the liver and spleen is similar to those from other organs, while the tumor exhibits much stronger fluorescence in the ex vivo image.

Efficacy and Acceptability of 1 Liter of Polyethylene Glycol with Ascorbic Acid vs. 2 Liters of Polyethylene Glycol Plus Mosapride and Sennoside for Colonoscopy Preparation.

BACKGROUND [color=black]Bowel preparation is an important factor for an optimal outcome of colonoscopy. Recently, polyethylene glycol (PEG) solution has been in common use for bowel cleansing for colonoscopy, but some patients are intolerant of PEG because of taste or volume. A low-volume PEG administered with ascorbic acid solution (PEG-Asc) was designed to improve tolerability, but the administration of this method is more complex than that with PEG alone. This study aimed to compare bowel cleansing efficacy, safety, and tolerability of 1 L PEG-Asc with a 2 L PEG preparation with use of sennosides and mosapride.[/color] MATERIAL AND METHODS [color=black]This was a prospective, single-center, non-inferiority trial that included 112 patients (PEG-Asc group, 68; PEG group, 44). The primary endpoint was the efficacy of colon cleansing assessed by endoscopists using a validated 4-point scale according to the Aronchick scale and was verified by a blinded investigator. Acceptability, tolerability, and adenoma detection rate (ADR) of these 2 regimens were secondary endpoints.[/color][color=black] [/color] RESULTS [color=black]We found no statistically significant differences between the groups in colon-cleansing efficacy or in the adenoma detection rate (ADR). Moreover, overall, patients significantly favored PEG-Asc over PEG, reflecting better acceptance of PEG-Asc. Additionally, more patients favored PEG-Asc over PEG for a hypothetical future colonoscopy. [/color] CONCLUSIONS [color=black]The alternate 1 L PEG-Asc regimen and standard 2 L PEG regimen were clinically equivalent with respect to cleansing efficacy, safety, and ADR, and more patients favored PEG-Asc than PEG. This alternate regimen may improve patient compliance and acceptance of surveillance colonoscopy.[/color].

Comparative evaluation of treatment outcomes between temporary anchorage devices and Class III elastics in Class III malocclusions.

INTRODUCTION: Our objective was to elucidate the differences in treatment outcomes caused by the different mechanics of temporary anchorage devices (TADs) and Class III elastics in patients with Class III malocclusions. METHODS: Records of 23 patients with Angle Class III malocclusion were selected retrospectively. All had been treated with nonextraction comprehensive orthodontic treatment; 11 were treated with TADs and 12 with Class III elastics. Pretreatment and posttreatment lateral cephalograms were used for evaluation of the treatment outcomes. A paired t test and a Student t test were used for statistical analysis. RESULTS: In both groups, proper overjet and Class I molar relationships were achieved, and the occlusal plane was rotated counterclockwise. In the elastics group, distal tipping of the mandibular molars, extrusion of the mandibular incisors and maxillary molars, clockwise rotation of the mandibular plane angle, and increased ANB angle were observed. In the TADs group, distal tipping and intrusion of the mandibular molars, bodily movement of the mandibular incisors, and reduced mandibular plane angle were observed. CONCLUSIONS: In nonextraction treatment for Class III malocclusions, the mandibular plane angle was increased in the elastics group, whereas it was decreased in TADs group. Thus, we suggest that Class III elastics are preferred for low-angle, short-face patients, whereas TADs are preferred for high-angle, long-face patients.

A Single-center, Open-label, Randomized Controlled Clinical Trial to Evaluate the Efficacy and Safety of the Indirect Bonding Technique.

Although accurate bracket placement is essential for orthodontic treatment, many practitioners apply brackets indiscriminately with direct or indirect bonding techniques. Nonetheless, there have been few prospective clinical comparisons of the 2 techniques. We will therefore conduct a single-center, randomized control trial in 100 patients aged 12 years and diagnosed with malocclusion. All patients will receive orthodontic treatment using brackets with direct or indirect bonding techniques. The primary endpoints will be the total treatment time, occlusal index, discomfort at bonding, and oral hygiene after bonding. This study will clarify whether indirect bonding can improve the efficiency of orthodontic treatment.

Antero-posterior and vertical facial type variations influence the aesthetic preference of the antero-posterior lip positions.

UNLABELLED: SummaryObjectives: The purposes of this study were to investigate whether the antero-posterior and vertical facial type variations influenced the favoured lip positions and to elucidate whether the favoured lip positions differed between orthodontists and laypersons. METHODS: An average profile was constructed from a Japanese female with Class I occlusion and a well-balanced profile, as assessed by several cephalometric analyses. Nine facial types were composed by morphing the chin antero-posteriorly and/or vertically. Thirteen morphed lip profiles were constructed by moving the lips antero-posteriorly in the nine facial types, respectively. Seventy-seven Japanese laypersons and 30 orthodontists were asked to choose the top three most-favoured lip positions for each facial type. RESULTS: The protruded lip positions were significantly favoured for all the mandibular protrusive facial types. The retruded lip positions were significantly favoured for the short facial type of the antero-posteriorly average and mandibular retrusive-short facial types. Among the mandibular protrusive facial types, the protruded lip positions were significantly favoured for the long facial type. The retruded lip positions were statistically more attractive for orthodontists than laypersons on the antero-posteriorly average-short, mandibular protrusive-short, mandibular retrusive-vertically average, antero-posteriorly average-vertically average, and mandibular retrusive-long facial types. LIMITATIONS: Our data were limited by the specific ethnic groups and variety of facial types. CONCLUSION: The favoured antero-posterior lip position was affected by not only the antero-posterior facial disproportion but also by the vertical dimensions. The favoured lip positions differed between orthodontists and laypersons. These results might be helpful in deciding between extraction and non-extraction treatment in borderline cases.

Effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviours and crystal structures.

BACKGROUND/OBJECTIVE: To investigate the effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviours and crystal structures. MATERIALS/METHODS: Five thermoplastic materials, polyethylene terephthalate glycol (Duran®, Scheu Dental), polypropylene (Hardcast®, Scheu Dental), and polyurethane (SMP MM®, SMP Technologies) with three different glass transition temperatures (T g) were selected. The T g and crystal structure were assessed using differential scanning calorimetry and X-ray diffraction. The deterioration of mechanical properties by thermal cycling and the orthodontic forces during stepwise temperature changes were investigated using nanoindentation testing and custom-made force-measuring system. The mechanical properties were also evaluated by three-point bending tests; shape recovery with heating was then investigated. RESULTS: The mechanical properties for each material were decreased significantly by 2500 cycles and great decrease was observed for Hardcast (crystal plastic) with higher T g (155.5°C) and PU 1 (crystalline or semi-crystalline plastic) with lower T g (29.6°C). The Duran, PU 2, and PU 3 with intermediate T g (75.3°C for Duran, 56.5°C for PU 2, and 80.7°C for PU 3) showed relatively stable mechanical properties with thermal cycling. The polyurethane polymers showed perfect shape memory effect within the range of intraoral temperature changes. The orthodontic force produced by thermoplastic appliances decreased with the stepwise temperature change for all materials. CONCLUSIONS/IMPLICATIONS: Orthodontic forces delivered by thermoplastic appliances may influence by the T g of the materials, but not the crystal structure. Polyurethane is attractive thermoplastic materials due to their unique shape memory phenomenon, but stress relaxation with temperature changes is expected.

Relationship between orthodontic expertise and perception of need for orthodontic treatment for mandibular protrusion in Japan.

The aims of this study were to investigate how the Peer Assessment Rating (PAR index) predicts the perceived need for orthodontic treatment of mandibular protrusion in Japanese subjects, and to elucidate whether the perceived need for treatment was affected by the raters' orthodontic expertise. The subjects were 110 dental students and 32 orthodontists. We showed them casts of 10 untreated mandibular protrusion cases and gave them a questionnaire in which they had to describe their perceptions of the orthodontic treatment needs using a 10-point visual analog scale (VAS). The PAR index was used for cast evaluation. The PAR index scores showed significant correlations with the VAS scores. In casts with a low PAR score, there were no differences in the VAS scores between orthodontists and students. In casts with a PAR score greater than 23, the orthodontists perceived a significantly greater treatment need than did the students;for scores of 22, 28, and 29, students who had received orthodontic treatment themselves were more likely to perceive the treatment need. The PAR index is a good clinical predictor for assessing the perceived treatment needs for mandibular protrusion. Perception of the need for orthodontic treatment for mandibular protrusion depended on the degree of orthodontic expertise in Japanese subjects.

Effect of dielectric spacer thickness on signal intensity of surface plasmon field-enhanced fluorescence spectroscopy.

Surface plasmon field-enhanced fluorescence spectroscopy (SPFS) combines enhanced field platform and fluorescence detection. Its advantages are the strong intensity of the electromagnetic field and the high signal/noise (S/N) ratio due to the localized evanescent field at the water/metal interface. However, the energy transfer from the fluorophore to the metal surface diminishes the fluorescence intensity, and this reduces the sensitivity. In this study, we tested whether polystyrene (PSt) could act as a dielectric layer to suppress the energy transfer from the fluorophore to the metal surface. We hypothesized that this would improve the sensitivity of SPFS-based immunoassays. We used α-fetoprotein (AFP) as a model tumor biomarker in the sandwich-type immunoassay. We determined the relationship between fluorescent signal intensity and PSt layer thickness and compared this to theoretical predictions. We found that the fluorescence signal increased by optimally controlling the thickness of the PSt layer. Our results indicated that the SPFS-based immunoassay is a promising clinical diagnostic tool for quantitatively determining the concentrations of low-level biomarkers in blood samples.

Relationship between impacts attributed to malocclusion and psychological stress in young Japanese adults.

Identifying risk factors is important to prevent a wide range of health-damaging behaviours and to improve the quality of life of young people. The aim of this study was to investigate the relationship between impacts on daily performance attributed to malocclusion and psychological stress in healthy young Japanese adults. Medical and oral health data were collected during a cross-sectional examination conducted by the Health Service Center of Okayama University. Systemically healthy non-smoking students aged 18 and 19 years (n = 641; 329 males and 312 females) were included. Malocclusion was defined using a modified version of the Index of Orthodontic Treatment Need (IOTN). The impacts on daily performance attributed to malocclusion and psychological stress were assessed using self-reported questionnaires, the condition-specific oral impacts on daily performances (CS-OIDP), and the Hopkins Symptoms Checklist. Mann-Whitney U- and chi-square tests and structural equation modelling (SEM) were used for statistical analysis. Forty per cent of subjects had a malocclusion (n = 255). Subjects with impacts on daily performance had a significantly higher prevalence of malocclusion than those without impacts (P < 0.001). SEM showed that psychological stress, especially interpersonal sensitivity and depression, was significantly correlated with CS-OIDP and malocclusion. Negative impacts on daily performance attributed to malocclusion may contribute to psychological stress in young Japanese adults.

Expression of Ten-m/Odz3 in the fibrous layer of mandibular condylar cartilage during postnatal growth in mice.

It has been speculated that the mandibular condyle develops via the differentiation of the fibroblast-like cells covering the condyle into chondrocytes; however, the developmental mechanisms behind this process have not been revealed. We used laser-capture microdissection and cDNA microarray analysis to elucidate the genes that are highly expressed in these fibroblast-like cells. Among these genes, the transcription of Ten-m/Odz3 was significantly increased in the fibroblast-like cells compared with other cartilage tissues. For the first time, we describe the temporal and spatial expression of Ten-m/Odz3 mRNA in relation to the expression of type I, II, and X collagen mRNA, as determined by in-situ hybridization in mouse mandibular condylar cartilage and mouse femoral cartilage during the early stages of development. Ten-m/Odz3 was expressed in the fibrous layer and the proliferating and mature chondrocyte layers, which expressed type I and II collagen, respectively, but was not detected in the hypertrophic chondrocyte layer. Furthermore, we evaluated the in-vitro expression of Ten-m/Odz3 using ATDC5 cells, a mouse chondrogenic cell line. Ten-m/Odz3 was expressed during the early stage of the differentiation of mesenchymal cells into chondrocytes. These findings suggest that Ten-m/Odz3 is involved in the differentiation of chondrocytes and that it acts as a regulatory factor in the early stages of the development of mandibular condylar cartilage.

A multicenter prospective cohort study on the effect of smoking cessation on periodontal therapies in Japan.

Few prospective studies have reported the effects of periodontal therapy on patients who attempted to quit smoking. This study aimed to assess how smoking cessation affects periodontal therapy. Twenty-five smokers with periodontitis were investigated by dividing them into two groups, a smoking cessation support group and a continued smoking group. Those in the support group received counseling and nicotine replacement therapy, followed by periodontal treatment conducted by dentists who had completed an e-learning course on smoking cessation. Clinical parameters were measured at baseline, 3, and 6 months. Most clinical parameters improved for those in the smoking cessation support group. There were no significant improvements in bleeding on probing (BOP) or the number of severe periodontal disease sites in the continued smoking group. Probing pocket depth (PPD) and clinical attachment levels (CAL) at sites that received scaling and root planing (SRP) significantly improved in all subjects. BOP did not improve at reevaluation in the smoking relapse subgroup. Patients in the smoking cessation support program led by dental professionals showed more improvement in BOP than those in the continued smoking group.

Biodistribution/biostability assessment of siRNA after intravenous and intratracheal administration to mice, based on comprehensive analysis of in vivo/ex vivo/polyacrylamide gel electrophoresis fluorescence imaging.

We performed in vivo/ex vivo/polyacrylamide gel electrophoresis (PAGE) fluorescence imaging of near-infrared fluorescence (NIRF)-labeled siRNA (Cy5.5-siGL3) in mice to investigate the validity of each fluorescence imaging result as the biodistribution/biostability assessment of siRNA. Statistically significant correlations could be obtained between the in vivo and ex vivo fluorescence intensities of Cy5.5 in the relevant regions/tissues, except the lung region/tissue after intravenous administration. On PAGE fluorescence images with the naked formulation, there was no band corresponding to intact Cy5.5-siGL3 from all the tissues evaluated after intravenous administration, indicating that the fluorescence detected by in vivo and ex vivo fluorescence imaging was derived from degraded Cy5.5-siGL3 or free Cy5.5 cleaved from Cy5.5-siGL3. However, the band was detected from the lungs after intratracheal administration of the naked formulation, confirming higher stability of siRNA on the respiratory epithelium than in the blood. Regarding the polyethyleneimine formulation, the band was detected from all the tissues evaluated after intravenous administration and from the lungs after intratracheal administration, verifying the enhanced stability of siRNA in the body. These results clearly indicated the necessity of comprehensive analysis from in vivo/ex vivo/PAGE fluorescence imaging to precisely assess the distribution and stability of NIRF-labeled oligonucleotides including siRNA in the body.

Comparison of the intrusion effects on the maxillary incisors between implant anchorage and J-hook headgear.

INTRODUCTION: Recently, miniscrews have been used to provide anchorage during orthodontic treatment, especially for incisor intrusion. Miniscrews during incisor intrusion are commonly used in implant orthodontics. Traditionally, effective incisor intrusion has been accomplished with J-hook headgear. In this study, we compared the effect of incisor intrusion, force vector, and amount of root resorption between implant orthodontics and J-hook headgear. METHODS: Lateral cephalometric radiographs from 8 patients in the implant group and 10 patients in the J-hook headgear group were analyzed for incisor retraction. The estimated force vector was analyzed in the horizontal and vertical directions in both groups. Root resorption was also measured on periapical radiographs. RESULTS: In the implant group, significant reductions in overjet, overbite, maxillary incisor to palatal plane, and maxillary incisor to upper lip were observed after intrusion of the incisors. In the J-hook headgear group, significant reductions in overjet, overbite, maxillary incisor to upper lip, and maxillary incisor to SN plane were observed after intrusion of the incisors. There were significantly greater reductions in overbite, maxillary incisor to palatal plane, and maxillary incisor to upper lip in the implant group than in the J-hook headgear group. Estimated force analysis resulted in significantly more force in the vertical direction and less in the horizontal direction in the implant group. Furthermore, significantly less root resorption was observed in the implant group compared with the J-hook headgear group. CONCLUSIONS: The maxillary incisors were effectively intruded by using miniscrews as orthodontic anchorage without patient cooperation. The amount of root resorption was not affected by activating the ligature wire from the miniscrew during incisor intrusion.

Dental and craniofacial characteristics in a patient with leprechaunism treated with insulin-like growth factor-I.

Leprechaunism is an autosomal recessive disease characterized by elfin-like faces, loss of glucose homeostasis, and severe insulin resistance. This disease is caused by inherited defects of the insulin receptor and is lethal early in life. Perhaps for this reason, the teeth and craniofacial features of patients with leprechaunism have never been reported. In the present case, the patient had been diagnosed with leprechaunism with mutation in the insulin receptor gene and had treatment with recombinant human insulin-like growth factor I (IGF-I) starting at the age of 1 year 7 months. It is of interest that all of his teeth were extremely large and subsequently showed severe crowding in the dental arches. He also showed a large tongue with an anterior open bite. He had a convex facial profile with a remarkably steep mandibular plane angle and large gonial angle. This is the first report of the characteristic phenotypes of the teeth and craniofacial morphology of a patient with leprechaunism treated with IGF-I. In addition, the possible association between these features and long-term IGF-I treatment is discussed.

Clinical effect of CO(2) laser in reducing pain in orthodontics.

OBJECTIVE: To test the hypothesis that there is no difference in the pain associated with orthodontic force application after the application of local CO(2) laser irradiation to the teeth involved. MATERIALS AND METHODS: Separation modules were placed at the distal contacts of the maxillary first molars in 90 patients in this single-blinded study. In 60 of these patients (42 females and 18 males; mean age = 19.22 years) this was immediately followed by laser therapy. The other 30 patients (18 females and 12 males; mean age = 18.8 years) did not receive active laser irradiation. Patients were then instructed to rate their levels of pain on a visual analog scale over time, and the amount of tooth movement was analyzed. RESULTS: Significant pain reductions were observed with laser treatment from immediately after insertion of separators through day 4, but no differences from the nonirradiated control side were noted thereafter. No significant difference was noted in the amount of tooth movement between the irradiated and nonirradiated group. CONCLUSIONS: The hypothesis was rejected. The results suggest that local CO(2) laser irradiation will reduce pain associated with orthodontic force application without interfering with the tooth movement.

CXCR4-targeted Nanoparticles Reduce Cell Viability, Induce Apoptosis and Inhibit SDF-1α Induced BT-549-Luc Cell Migration In Vitro.

BACKGROUND: CXCR4 possesses a critical role in several intracellular events such as chemotaxis, invasion and adhesion, which are associated with metastasis of cancer cell. OBJECTIVE: In this study, CXCR4 targeted polymeric nanoparticle was developed for delivering cytotoxic drug and blocking the chemokine induced migration of cells expressing CXCR4. METHOD: A peptide which was a linear form of CXCR4 antagonist (LFC131) was attached to PLGA nanoparticles (LFC131-NPs) and PLGA nanoparticles encapsulating DOX (LFC131-DOX-NPs). The cellular binding and internalization of LFC131-DOX-NPs were investigated. RESULTS: The binding and internalization of LFC131-DOX-NPs were higher and more rapidly compared to unconjugated NPs. LFC131-NPs blocked SDF-1α induced migration of BT-549-Luc cells. MTT assays demonstrated that LFC131-NPs and LFC131-DOX-NPs decreased cell viability in a dose dependent manner in 24, 72 and 120 h incubation. CONCLUSION: A treatment concept of blocking breast cancer cell migration from interaction with SDF- 1α by using LFC131-NPs and then attacking breast cancer cells with doxorubicin might increase the efficacy of current breast cancer treatment.

Early orthodontic treatment and long-term observation in a patient with Morquio syndrome.

Early orthodontic treatment and long-term observation in a patient with Morquio syndrome were demonstrated. To date, there are no case reports describing orthodontic treatment in such a patient. The patient showed spaced maxillary and mandibular arches with a tongue thrust habit at age seven years eight months. She also showed a protruded upper lip, labial inclination of the upper and lower anterior teeth, and thin enamel. The tongue thrust habit disappeared after the application of a removable orthodontic appliance. The spaced dentition in the upper and lower arches improved after treatment with a fixed appliance with closing loop arch wire (0.017 x 0.025") and bands on the upper and lower molars. We did not use an edgewise appliance because of the thin enamel. The protruded upper lip and labial inclination of the upper and lower anterior teeth were also improved after treatment, but optimal intercuspation of the teeth was not achieved. However, optimal intercuspation of the teeth was achieved after long-term observation and the masticatory function was improved. It was suggested that early orthodontic treatment could improve the malocclusion in a patient with Morquio syndrome and that improvement of masticatory function could be achieved during a long-term retention period.

The effects of luminance, size, and duration of a visual line on apparent vertical while the head is being inclined in roll.

We determined orientation of a line that is seen to be vertical (i.e., apparent vertical) while the head is inclined with the trunk upright. In this condition, it has been documented that apparent vertical is independent of head orientation (i.e., orientation constancy) or is in a direction opposite to the head inclination (i.e., the Müller effect). In this study, we have focused not only on the effect of head inclination but also on visual parameters of the line that was used to indicate apparent vertical. As the visual parameters, size (5.5° and 22° in visual angle), duration (0.1 s, 3 s, and no time limit), and luminance (0.026, 0.003, and 0.001 cd/m(2) against total darkness) were varied with the head being inclined within ±30°. The main findings were: 1) the Müller effect was at best 2°, but the head inclination was judged to be much larger than it was; 2) the correlation between apparent vertical and the judgmental error of head inclination was significant but was not very high (r = -0.20); 3) the line of short duration or of low luminance facilitated the Müller effect; and 4) the magnitude of the Müller effect was large when the head was inclined to the right rather than to the left. These findings were compared with the predictions from the theory of allowing for apparent head position, the theory of ocular countertorsion, and the sensory-tonic field theory. Many aspects of the results were consistent with the predictions from the sensory-tonic field theory.

High-cycle fatigue behavior of beta-titanium orthodontic wires.

This study investigated high-cycle fatigue behavior in three ß-Ti wires (TMA, Resolve, Gummetal). Fatigue was evaluated using a static three-point bending test and a high-cycle fatigue test with a three-point bending mode. The surfaces of fractured wires were observed with scanning electron microscopy, and the post-fatigue crystal structures were determined by micro-X-ray diffraction. The Gummetal wire exhibited the lowest elastic modulus, bending strength and fatigue limit, and exhibited the highest resilience of the three types of wire studied. However, no difference in the number of cycles to failure was observed among the three types of wire. The fatigue crack propagation and rapid propagation regions of all wires contained single-phase ß-Ti. The elastic modulus and bending strength influenced the fatigue limit, although these properties did not affect the number of cycles to fracture. The three types of ß-Ti wires exhibited similar risks of wire fracture.