Elastic Wear Research Articles

Outcome assessment of orthodontic clear aligner vs fixed appliance treatment in adolescents with moderate to severe malocclusions.

To compare the efficacy and efficiency of treatment with clear aligners (CAT) vs fixed appliances (FAT) in adolescents with Class I and II moderate to severe malocclusions. One operator's (Garfinkle) cases from 2014 to 2019, started at age 12-18 years, with pre- and posttreatment records were identified and used according to an institutional review board-approved protocol. Records were measured by two calibrated, blinded investigators, aided by software (OrthoCAD [Cadent, Fairview, N.J.], Dolphin Imaging & Management Solutions [Chatsworth, Calif]). Discrepancy index (DI) and cast radiograph evaluation (CRE) scores, treatment duration, number of scheduled and emergency visits, and reported appliance and interarch elastic wear compliance were compared between groups using Wilcoxon rank sum and Fisher's exact tests. Cephalometric superimpositions were completed to evaluate craniofacial growth and dental changes. Records from 72 cases met the criteria and were included. For the 47 CAT and 25 FAT cases, mean DI (21 ± 5 and 24 ± 8, respectively; P = .20) and CRE (35 ± 10 and 34 ± 9, respectively; P = .90) scores were not significantly different. Other case attributes and reported appliance and interarch elastic wear compliance were also not significantly different. CAT vs FAT cases had significantly smaller treatment durations (24 ± 6 vs 27 ± 5 months; P = .01) and visit numbers (16 ± 5 vs 24 ± 4; P < .01), but emergency visit numbers were not significantly different (2 ± 2 vs 3 ± 2; P = .08). In adolescents with Class I and II malocclusions and moderate to severe DI scores, on average, CAT vs FAT cases were completed 3 months faster with eight fewer visits, but treatment efficacy was not significantly different.

Effects of Class II elastics during growth on the functional occlusal plane according to skeletal pattern and extraction vs nonextraction.

To investigate the effect of Class II intermaxillary elastics on the functional occlusal plane (FOP) of growing patients. A total of 50 participants aged 11 to 16 years were selected from a university clinic archive >1-year after treatment and after undergoing 6 months of Class II elastic wear, taking pretreatment (T0) and posttreatment (T1) lateral cephalometric radiographs, and consenting to participate at recall (T2). Participants were divided into 3 groups according to skeletal pattern or into 2 groups according to treatment with extraction (E) or nonextraction (NE). Angular changes of FOP relative to the Sella-Nasion (SN), mandibular plane (MP), and Frankfort horizontal (FH) were compared within and between groups. A statistically significant reduction of FOP-SN/FH, but not of FOP-MP, was found from T0-T1-T2 when all patients were grouped together. FOP-SN/MP/FH was significantly the largest in the patients with a hyperdivergent skeletal pattern, but lowest in the patients with a hypodivergent skeletal pattern at T0, T1, and T2 (P < .032). FOP-MP at T0-T2 was statistically larger in group E than in group NE (P < .02). No differences were found for FOP changes (change before treatment minus after treatment and change after treatment minus 1 year after treatment) between different skeletal patterns (P > .433) and treatment groups (P > .193). Use of Class II elastics during the growth period was not found to show adverse effects on FOP rotation. Neither skeletal pattern nor treatment modality differed in the response to Class II elastics with regard to FOP changes. Individual patient growth pattern must be taken into consideration when treatment planning the use of Class II elastics. Orthodontists should take into account individual skeletal and growth patterns while using Class II elastics.

Compositional library of β Ti-Nb-Zr alloy coatings applied to biomedical prostheses

The β Ti-based alloys have attracted considerable interest as biomedical materials due to their unique characteristics, such as excellent biocompatibility, low elastic modulus, low density, and corrosion and wear resistances in biological environment. Ti, Nb, and Zr are non-toxic and non-allergenic biocompatible metals, and the addition of Nb and Zr to Ti favors the mechanical compatibility between the alloy and the bone. The addition of Nb to Ti yields to the stabilization of the β phase, and the addition of Zr to the Ti-Nb system increases the β stabilizing effect. However, the ideal amounts of the constituent elements in the Ti-Nb-Zr ternary system are uncertain. Combinatorial strategies allow for the production and characterization of many alloys simultaneously, and magnetron sputtering has been used to generate compositional libraries for ternary thin films and coatings. In this study, Ti-Nb-Zr ternary alloy coatings were deposited by magnetron sputtering on a Si (100) wafer substrate. The Ti, Nb, and Zr targets were positioned in a triangular configuration below the Si substrate. A composition gradient was formed over all the substrate area. Chemical, structural, and morphological analyses were performed by energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and atomic force microscopy.

Effects of self-ligating brackets and other factors influencing orthodontic treatment outcomes: A prospective cohort study.

ObjectiveThe purpose of this study was to evaluate the effects of self-ligating brackets (SBs) and other factors that influence orthodontic treatment outcomes.MethodsThis two-armed cohort study included consecutively treated patients in a private practice. The patients were asked to choose between SBs and conventional brackets (CBs); if any patient did not have a preference, he or she was randomly allocated to the CB or SB group. All patients were treated using an identical archwire sequence. Evaluated parameters were as follows treatment duration, number of bracket failures, poor oral hygiene, poor elastic wear, extraction, use of orthodontic mini-implants (OMI), OMI failure, American Board of Orthodontics (ABO) Discrepancy Index (DI), arch length discrepancy, and ABO Cast-Radiograph Evaluation (CRE) score. Stepwise regression analysis was performed to generate the equation for prediction of the CRE.ResultsThe final sample comprised 134 patients with an average age of 22.73 years. The average DI, CRE, and treatment duration were 21.81, 14.25, and 28.63 months, respectively. Analysis of covariance showed a significant difference in CRE between the CB and SB groups after adjusting for the effects of confounding variables. Stepwise regression analysis using four variables, namely extraction, SB use, poor elastic wear, and additional appliance use, could explain only 25.2% of the variance in the CRE.ConclusionsAlthough the CRE was significantly better for CBs than for SBs, the clinical significance of this result seems to be limited. Extraction, SB use, poor elastic wear, and additional appliance use may have significant effects on treatment outcomes.

Optimized Laboratory Test Condition to Predict Tire Tread Wear

Laboratory test condition to predict tire tread wear was discussed, using the FPS wear test equipment manufactured by Ueshima Seisakusho Co. Ltd. Sample load was determined based on the sample dynamic footprint and inflation pressure of different tire groups. Most tire groups evaluate wear rate by volume loss per distance with the exception of giant mining tires which evaluate volume loss per hours. In light of truck, bus and passenger tires, the laboratory test in the present paper employed the volume loss per distance. In such case, slip ratio correlated with wear rate better than slip speed. The surface of the worn sample and wear debris indicated that the laboratory wear mechanism was identical to road wear mechanism which was considered plastic wear (P-wear) instead of the conventional elastic wear (E-wear).

Factors influencing treatment efficiency.

The purpose of this cohort study was to evaluate the effect of self-ligating brackets (SB) and other related factors that influence orthodontic treatment time. This was a two-armed prospective study. Consecutively treated patients who were recruited from a private practice were enrolled and asked to choose between SB and conventional brackets (CB). If the patient did not have a preference, that patient was randomly allocated. An identical archwire sequence was used, and all patients were treated by a single orthodontist. Treatment duration, number of bracket failures, poor oral hygiene, poor elastic wear, whether or not to orthodontic mini-implants (OMI) were used, OMI failure, extraction, American Board of Orthodontics Discrepancy Index, and arch length discrepancy were measured and statistically analyzed using t-tests, correlation analysis, and analysis of covariance (ANCOVA). Stepwise regression analysis was conducted to generate an equation to predict treatment duration. A total of 134 patients with an average age of 22.73 years were included. The average treatment duration was 28.63 months. ANCOVA showed no significant difference in treatment duration between CB and SB. Stepwise regression analysis could explain 64.6% of the variance in treatment duration using five variables. SB did not exhibit a significant reduction in treatment time as compared with CB. Patient cooperation, extractions, and malocclusion severity had a significant impact on treatment duration.

A Study of Wear Articular Cartilage of Synovial Human Knee Joint Using Non-Newtonian Elastic Mathematical Model

In this paper, the wear in layers of articular cartilage was calculated, parameters effective on elastic deformation were studied in normal and diseased knee joints, and relations between elastic deformation and squeeze film characteristics under lubrication condition were discussed with using a mathematical model. Conferring to the results obtained, elastic deformation effects on the performance of synovial human knee joint were analyzed from medical and dynamics perspectives. Relationships between elastic deformation and wear of layers were also discussed.

3D effects of a bone-anchored intra-oral protraction in treating class III growing patient: a pilot study

ObjectivesThe aim of this prospective case series study is to assess the three-dimensional (3D) skeletal and soft tissue effects of the alternate rapid maxillary expansion and constriction (Alt-RAMEC) protocol in conjunction with a miniscrew-supported class III elastic wear in class III growing patients.Materials and methodsFourteen consecutive participants (mean age 12.05 ± 1.09 years), who displayed class III malocclusions with retrognathic maxillae, were recruited. A cone beam computed tomography (CBCT) scan was acquired before commencing treatment (T1). All participants were treated with a tooth-bone-borne rapid maxillary expansion (hybrid MARME) appliance that was activated by the Alt-RAMEC protocol for 9 weeks. This was followed by full-time class III elastics, delivering 400 g/side, to protract the maxilla. When a positive overjet was achieved, protraction was ceased and a post-treatment CBCT scan (T2) was taken. The 3D analysis of pre- and post-treatment CBCT scans was blinded. The scans were registered on the anterior cranial base. The Euclidean distance between the two extracted surface models of the pre- and post-treatment scans was displayed as a color surface map.ResultsAll participants completed the intervention successfully. The majority of the participants showed protraction of the anterior maxillary region (71.4%) and in the zygomatic processes (64.2%). The maxilla significantly protracted (SNA 1.87° ± 1.06°; Vert.T-A 3.29 ± 1.54 mm), while the mandibular base significantly redirected posteriorly (SNB − 2.03° ± 0.85°, Vert.T-B − 3.43 ± 4.47 mm) and that was reflected on the ANB and Wits measurements. No adverse effects were observed.ConclusionClass III elastics combined with the Alt-RAMEC activation protocol of the hybrid MARME appliance is an effective treatment method for mild/moderate class III malocclusions. A long-term follow-up and comparisons with other treatment modalities are required.

Nanoindentation and nanoscratch properties of graphene nanoplatelets reinforced spark plasma sintered aluminium-based nanocomposite

ABSTRACTAluminium matrix nanocomposites reinforced with 0.5 and 1wt% functionalized graphene nanoplatelets were fabricated via spark plasma sintering (SPS). Nanoindentation and nanoscratch tests were performed on the nanocomposites to evaluate the mechanical and tribological properties at small length scales. Al nanocomposite reinforced with 0.5wt% graphene nanaoplatelets (GNP) showed homogenous porosity free microstructure, whereas a significant amount of porosities were evident in Al-1.0wt% GNP nanocomposite. Indentations and scratches were performed at 2000 μN constant load using standard Berkovich indenter. Elastic modulus, nanohardness and wear volume were measured for the sintered samples. Al nanocomposite reinforced with 0.5wt% GNP showed high hardness and wear resistance as compared to that of monolithic aluminium. Improvement in the wear resistance was discussed with respect to strengthening effect by addition of GNPs.

Effects of Cr and Nb Additions on Sliding Wear Behaviors of the FePSiB Coatings

The tribological properties of the FePSiB amorphous/nanocrystalline coatings with Cr and Nb additions were investigated in reciprocating mode against tungsten carbide friction coupling with different dry sliding conditions. The wear rates of the FePSiB-based coatings increase linearly with the normal load and sliding speed. The coatings with Cr and Nb promote the formation of successive and compact oxide film on friction surface, which decreases significantly wear rate of the coating. Nano-mechanical characterization done to map the correlation between the elastic properties and wear resistance. The main damage mechanisms of the FePSiB-based coatings under dry friction conditions are abrasion wear, delamination failure and oxidation wear.

A novel method for treatment of Class III malocclusion in growing patients

BackgroundManagement of Class III malocclusion is one of the most challenging treatments in orthodontics, and several methods have been advocated for treatment of this condition. A new treatment protocol involves the use of an alternating rapid maxillary expansion and constriction (Alt-RAMEC) protocol, in conjunction with full-time Class III elastic wear and coupled with the use of temporary anchorage devices (TADs). The aim of this study was to evaluate the dento-skeletal and profile soft tissue effects of this novel protocol in growing participants with retrognathic maxilla.MethodsFourteen growing participants (7 males and 7 females; 12.05 ± 1.09 years), who displayed Class III malocclusions with retrognathic maxilla, were recruited. Pre-treatment records were taken before commencing treatment (T1). All participants had a hybrid mini-implant-supported rapid maxillary expansion (MARME) appliance that was activated by the Alt-RAMEC protocol for 9 weeks. Full-time bone-anchored Class III elastics, delivering 400 g/side, were then used for maxillary protraction. When positive overjet was achieved, protraction was ceased and post-treatment records were taken (T2). Linear and angular cephalometric variables were blindly measured by one investigator and repeated after 1 month. An error measurement (Dahlberg’s formula) study was performed to evaluate the intra-examiner reliability. A paired-sample t test (p < 0.05) was used to compare each variable from T1 to T2.ResultsTreatment objectives were achieved in all participants within 8.5 weeks of protraction. The maxilla significantly protracted (SNA 1.87°± 1.06°; Vert.T-A 3.29± 1.54 mm p < 0.001), while the mandibular base significantly redirected posteriorly (SNB −2.03° ± 0.85°, Vert.T-B − 3.43± 4.47 mm, p < 0.001 and p < 0.05 respectively), resulting in a significant improvement in the jaw relationship (ANB 3.95°± 0.57°, p < 0.001; Wits 5.15± 1.51 mm, p < 0.001). The Y-axis angle increased significantly (1.95° ± 1.11°, p < 0.001). The upper incisors were significantly proclined (+ 2.98°± 2.71°, p < 0.01), coupled with a significant retroclination of the lower incisors (− 3.2°± 3.4°, p < 0.05). The combined skeletal and dental effects significantly improved the overjet (5.62± 1.36 mm, p < 0.001) and the soft tissue Harmony angle (2.75° ± 1.8°, p < 0.001).ConclusionsClass III elastics, combined with the Alt-RAMEC activation protocol of the MARPE appliance, is an efficient treatment method for mild/moderate Class III malocclusions. The long-term stability of these changes needs further evaluation.

Does Text Message Reminder Help Orthodontic Patients to Wear Intra-Oral Elastics During the Treatment?

Objective: To determine if text messaging reminders regarding intra oral elastic wear have any influence on the level of compliance in an orthodontic population. Materials & Methods: Eighty orthodontic patients were considered out of which 40 patients (20 Males & 20 Females) were assigned to a text message group (Study Group) & 40 patients (20 Males & 20 Females) were assigned to a Non-text message group (Control group), who did not receive a reminder text message. Message was sent once daily for a period of one month. The participants were given a fixed number of elastics (60 per patient) at the start of the study and were asked to collect used elastics for the period of one month and counts of these were used to assess compliance. Results: Compliance with elastic wear had significant difference among patients. Female patients proved to be more compliant compared to males in both the groups. The study group returned more number of used elastics than the control group, suggesting increased compliance. Conclusion: A text message reminder system explaining the importance of wearing Intra-oral elastics sent to patients once daily is an effective way to improve compliance in orthodontic patients.

Microstructural Evolution and Strain Development in Metal Matrix Composites

Composite materials present interesting mechanical properties. The metal provides the toughness and the particles are adding elastic stiffness, strength, hardness and wear resistance. High energy X-ray diffraction has been used to characterize the microstructure evolution of two types of MMCs (titanium and steel matrix) reinforced with TiC particles.Evolutions of mass fraction and mean cell parameters shows the effect of reinforcement on the kinetics and mechanical state of the final composites.

Motivation and compliance with intraoral elastics

Intraoral elastics are commonly used in orthodontics and require regular changing to be effective. Unfortunately, poor compliance with elastics is often encountered, especially in adolescents. Intention for an action and its implementation can be improved using "if-then" plans that spell out when, where, and how a set goal, such as elastic wear, can be put into action. Our aim was to determine the effect of if-then plans on compliance with elastics. To identify common barriers to compliance with recommendations concerning elastic wear, semistructured interviews were carried out with 14 adolescent orthodontic patients wearing intraoral elastics full time. Emerging themes were used to develop if-then plans to improve compliance with elastic wear. A prospective pilot study assessed the effectiveness of if-then planning aimed at overcoming the identified barriers on compliance with elastic wear. Twelve participants were randomized equally into study and control groups; the study group received information about if-then planning. The participants were asked to collect used elastics, and counts of these were used to assess compliance. A wide range of motivational and volitional factors were described by the interviewed participants, including the perceived benefits of elastics, cues to remember, pain, eating, social situations, sports, loss of elastics, and breakages. Compliance with elastic wear was highly variable among patients. The study group returned more used elastics, suggesting increased compliance, but the difference was not significant. The use of if-then plans might improve compliance with elastic wear when compared with routine clinical instructions.

Orthodontic apps at fingertips.

BackgroundSmartphone usage has spread to many settings including that of healthcare and dentistry with numerous potential and realized benefits. The ability to download custom-built software applications (apps) has created new opportunities for orthodontists to integrate technology into clinical practice and patients to collect the information about orthodontics and help them during their treatment. The purpose of this study is to provide a summary of the orthodontic apps currently available for orthodontic patients as well as ‘practicing clinicians’.MethodThree smartphones and two tablets were used to search three operating systems (Android, Apple, and Windows) using the keywords ‘braces’, ‘orthodontist’, ‘model analysis’, and ‘orthodontics’.ResultsAndroid and Apple operating systems accumulate all of the apps that are thought to be related to orthodontic clinicians and patients. Clinician's apps (17) are those related to orthodontic news (2), publication (4), products (3), and diagnosis (4) and practice management (3) while patient apps (17) are those related to orthodontic education (4), simulator (5), related to reminding patients about elastic wear (3), progress tracker of treatment (4), and orthodontic products (1).ConclusionIn the generation of technology, the use of smartphones and tablets has made life simple. The use of these technologies can be a boon both for the orthodontist and the patients as it aids both in treatment planning and progress in enhancing the treatment outcome.Electronic supplementary materialThe online version of this article (doi:10.1186/s40510-014-0036-y) contains supplementary material, which is available to authorized users.

Temporary skeletal anchorage devices: The case for miniscrews

5 According to Newton's Third Law, for every action, there is an equal and opposite reaction. Orthodontists must acknowledge this law every time they try to move teeth. Simply stated, every desired tooth movement has the potential to simultaneously create an undesired tooth movement. Orthodontic anchorage is defined as the resistance to such undesired tooth movement and can be achieved by more or less predictable methods. For space closure, 3 anchorage situations are traditionally defined by the ratio of incisor retraction to molar protraction. Maximum anchorage describes space closure mostly by incisor retraction and, to a lesser degree, by molar protraction (ratio of 2:1). Moderate anchorage comes with equal parts of incisor retraction and molar protraction (ratio of 1:1), whereas minimal anchorage allows spaces to close mostly by molar protraction and less by incisor retraction (ratio of 1:2). Traditionally, this type of anchorage control relies heavily on other appliances that add to the anchorage segment, such as compliance-dependent headgear or the noncompliance-dependent Nance appliance or, for instance, on elastic wear, which again depends on compliance. Although headgear incorporates skeletal structures into the anchorage segment (eg, high-pull headgear uses the occipital bone), elastics incorporate only other teeth into the anchorage segment, and this carries the potential for further side effects in the opposing dental arch. The philosophy behind skeletal anchorage is that if the reactive forces can be absorbed by skeletal structures, tooth movement can be limited to the desired therapeutic movements, and the undesirable reactive side effects can be prevented entirely. Such a situation can nowadays be created by temporarily implanting small devices into the patient's jawbone and using

The Effect of PVD Tungsten-Based Coatings on Improvement of Hardness and Wear Resistance

This article deals with the analysis and evaluation of coatings applications made by Physical vapour deposition on ceramics substrates. Main focus is on the application of tungsten and tungsten nitride coatings for functionally graded materials (FGM). The article focuses on analysis and evaluation of tungsten and tungsten nitride coatings with ceramics substrates. Firstly suitable deposition parameters of W and WN coatings, prepared by magnetron sputtering, were tested. Test coatings on tool steel substrate exhibited high adhesion and good mechanical and technological properties. Both tungsten and tungsten nitride coatings on selected ceramics substrates exhibited good mechanical a technological properties. Properties such as hardness, reduced elastic modulus and wear are discussed for each coating/substrate combination. Both coatings seem to be good candidates for application in field of FGM. The results of the presented experiment shows that the adhesion and the final quality of the coating depends on the type of chemical bond in the coating and in the substrate, and on the ability of the coating to deform plastically.

Orthodontic apps for smartphones

The increasing use of technology is rapidly changing our personal and professional lives. Smartphones allow users to access information in ways previously not possible and our patients may be accessing apps to source information about orthodontics and help them through their treatment. To provide an overview of the orthodontic apps currently available on four of the main operating systems with emphasis on those apps targeted towards new and existing orthodontic patients as well as practising clinicians. Four mobile devices were used to search four mobile operating systems (Android, Apple, Blackberry and Windows) using the key words 'braces', 'orthodontist', 'orthodontic' and 'orthodontics'. Android and Apple operating systems derived all of the apps considered relevant to orthodontic clinicians and patients. Clinician apps (11) related to orthodontic meetings (3), publications (3), products (3) and tooth ratio calculators such as Bolton (2). Patient apps (8) related to reminding patients about elastic wear (2) and aligner wear (2), dealing with orthodontic emergencies (2), orthodontic products (1) and a progress tracker of treatment (1). Apps are available for both orthodontic clinicians and patients; however, much of the information contained within them is often not independent and even more often not validated. Patients are increasingly likely to access apps and clinicians should direct patients to those that are most appropriate and useful.

Influence of laser scanning speed on Cu-Zr-Al composite coatings on Mg alloys

To improve the surface properties of magnesium alloys, a study was conducted on Cu-Zr-Al composite coatings on AZ91HP magnesium alloy by laser cladding. The influence of laser scanning speed on the microstructures and properties of the coatings was discussed. The coatings consist of amorphous phase, Cu8Zr3, and Cu10Zr7. With the increase of laser scanning speed, the amorphous phase content of the coatings increases and reaches 60.56wt% with the laser scanning speed of 2.0 m/min. Because of the influence of laser scanning speed on the amorphous and crystal phases, the coatings show the maximum elastic modulus, hardness, and wear resistance at the laser scanning speed of 1.0 m/min. At the laser scanning speed of 2.0 m/min, the coatings have the best corrosion resistance.

Structure and properties of low modulus titanium alloy Ti–26Nb–7Mo–12Zr

The calculation of the choice of a new low modulus titanium β alloy was described. The investigations of the structure and properties (mechanical, tribological and corrosive) of low modulus titanium β alloy Ti–26Nb–7Mo–12Zr after mechanical–thermal processing were carried out. An analysis of the results of experimental research showed that the formation of homogeneous fine grained structure by sheet rolling with subsequent annealing before quenching leads to decreased elastic modulus, increased plasticity and wear resistance. Therefore, new titanium β alloy designed in the present study, Ti–26Nb–7Mo–12Zr, is expected to have good properties as biomaterial.