Orthodontic Materials Research Articles

Chemical and mechanical characteristics of contemporary thermoplastic orthodontic materials

Abstract Aim The aim of the present study was to characterise the chemical and mechanical properties of contemporary thermoplastic orthodontic materials. Materials and methods Four thermoplastic materials were tested: Clear Aligner (Scheu-Dental), ACE and A+ (Dentsply), and Invisalign (Align Technology). Eight appliances were fabricated from each material and a small portion from each was analysed by ATR-FTIR spectroscopy. The appliances were cut and, following metallographic grinding and polishing, were subjected to instrumented indentation testing (IIT) employing a Vickers indenter. Martens Hardness (HM), Indentation Modulus (EIT), Elastic to Total Work Ratio (elastic index (ηIT)) and Indentation Creep (CIT) were determined according to ISO 14577-1. The mean values of the mechanical properties were statistically analysed by one way ANOVA and Tukey Kramer multiple comparison test at a = 0.05. Results ATR-FTIR analysis identified that Invisalign was a polyurethane-based material, whereas the others were based on polyester, polyethylene glycol terephthalate (PETG). Invisalign showed higher hardness and modulus values, a slightly higher brittleness and lesser creep resistance compared with the PETG-based products. Conclusions The materials tested showed significant differences in their chemical structure and mechanical properties and therefore differences in their clinical behaviour are anticipated.

Estimation of Release of Nickel and Chromium by Indian Made Orthodontic Appliance in Saliva.

With increasing use of Indian made orthodontic materials, need was felt to know nickel and chromium release from these material. This study was conducted on simulated appliances consisting of brackets (022″Roth, Modern orthodontics, Ludhiana, India), from second premolar to central incisor, buccal tube and 0.019×0.025- inch SS arch wires secured with SS ligatures. Immersion was done in artificial saliva. Samples were analysed to using Atomic Absorption Photospectrometer (GVC ScientificEquipment Pvt. Ltd Australia) at AES Laboratories (P) Ltd., Noida India on 1(st), 7(th), 14(th) and 28(th) day. SPSS (ver 17, Inc., Chicago, Illinois, USA) was used toperform the statistical analysis. Descriptive statistics i.e. median and 25 and75 percentiles were used. Peak nickel release was on 7(th) day and subsequently declined over 14(th) and 28(th) day. The peak level of chromium concentration was on 14(th) day, which declined thereafter. Average daily release of nickel and chromium over a period of one month was 97.368 μg/day and 47.664 μg/day respectively. The estimated release rates were approximately 32% and 16% of the reported average daily dietary.

Are claims made in orthodontic journal advertisements evidence-supported?

To examine the supporting evidence of advertisements published in six leading orthodontic journals. The 2012-2013 printed issues of American Journal of Orthodontics and Dentofacial Orthopedics, Australian Orthodontic Journal, Journal of Orthodontics, European Journal of Orthodontics, Journal of Clinical Orthodontics, and Journal of Orofacial Orthopedics were screened for advertisements implying superior performance compared with competitor products. Advertisements were classified according to type of product, availability, and currency of supporting references. A total of 99 unique advertisements claiming clinical benefit or superiority were identified. The overwhelming majority of the identified advertisements promoted appliance products (62.6%), orthodontic materials (14.1%), and dental operatory equipment, including imaging systems (12.1%). Advertisements were found to provide references or not regardless of the product type. Half of the advertisements referred to at least one peer-reviewed publication, whereas unpublished studies were cited by 25% of the advertisements. Most of the referenced articles were published within the past 5years. The scientific background of advertisements in the orthodontic literature appears limited. While surveillance of journal advertising needs to be regulated, clinicians are urged to critically appraise the claims being made in orthodontic print advertisements by consulting the associated existing evidence.

Quantitative assessment of Mutans Streptococci adhesion to coated and uncoated orthodontic archwires(In vitro study)

Background: The development of orthodontic biomaterials that attract less biofilm has been a goal for decades. Adhesion and colonization of cariogenic streptococci are considered to play key roles in the development of enamel demineralization related to orthodontic materials. The aim of this study was to quantitatively evaluate the Mutans streptococci adhesion to coated orthodontic archwires (Epoxy and Teflon) and uncoated archwires (stainless steel and nickel-titanium) with respect to incubation time in the presence and absence of saliva. Material and Method: Six types of archwires stainless steel and nickel titanium with two type of coating (Epoxy, Teflon) were used in this study. Twelve specimens of each archwire were incubated in sterilized unstimulated whole saliva (for the study group) and phosphate-buffered saline (for control group) for 2 hours, then incubated with suspension of Mutans streptococci allowed to adhere for (5,90,180 minutes). Adhesion was quantitated by a microbial culture technique by treating the archwires with adhering bacteria with trypsin and enumerating the colony forming unit (CFU) counts of bacteria recovered after cultivation by using Dentocult SM kit. Results: There was significant difference among the tested archwire types in each time interval with the highest bacterial adhesion on the NiTi archwires in the absence of saliva. In the presence of saliva, the results revealed non-significant difference at 5 min. while there was significant difference at 90 min and highly significant difference at 180 min. Conclusion: The adherence of Mutans streptococci was decreased in the presence of saliva on different archwires and the extended incubation time was significantly related to increase colony forming unit of Mutans Streptococci.

In vitro assessment of color changes of clear orthodontic elastomeric module materials after exposure to high-pigment beverages

BackgroundAesthetic elastomeric modules are subject to staining as a result of exposure to foods and beverages that can cause staining. The objective of this study was to assess, in vitro, color changes of clear orthodontic elastomeric module materials exposed to different staining beverages. MethodsSamples of four brands of clear orthodontic elastomeric modules (Morelli, TP Orthodontics, RMO, and GAC) were immersed for 15 minutes, three times weekly, in four beverages that can cause staining: coffee, cola, black tea, and red wine. Between sessions, samples were stored in artificial saliva at 37°C. Color changes were assessed after 4 weeks using the yellowness index (YI) (ASTM International D-6290/E-313-10 standard practices), calculated according to the Comission Internationale de l'Eclairage L*a*b* system with the aid of a spectrophotometer (range 0 to 100, with higher values indicating more yellowness). YI results were analyzed using ANOVA and the Tukey multiple comparisons test. ResultsDifferent degrees of discoloration were observed across the brands, despite the similarity of chemical structures. Coffee caused the most severe color change (mean ± SD YI 56.1 ± 0.79), followed by red wine (38.0 ± 0.78) and black tea (31.9 ± 0.63); these differences were significant. The GAC modules were the least affected by yellowness, whereas Morelli showed the highest degree of discoloration. Conclusion(s)The intake of foods and beverages with a high pigment content can cause discoloration of clear orthodontic elastomeric modules and thus lead to aesthetic complaints. Our findings can help practitioners select the most appropriate brand of elastomeric modules according to the dietary habits of each patient.

Availability of Instrument and Material In The Orthodontic Clinic, Faculty of Dentistry University of Malaya- An Audit

The audit aimed to investigate the availability of orthodontic instruments and materials at Faculty of Dentistry, University of Malaya. The standard was set as 100% of instruments and materials should be available when required for orthodontic treatment. The form comprised of six sections, which listed the commonly used instruments and materials involved in the procedures of impression taking, fitting and removal of molar bands, bonding and debonding of orthodontic brackets and activation of orthodontic appliances. The fifth section listed the less commonly used instruments and materials and a part for the clinician to list down instruments that were used but not listed in the form. Whilst the last section is for the clinician to list down the instruments or materials that were not available when requested. A total of 567 forms were completed and it was found that 97.6% instruments and 98.6% materials were available. Overall, 22 types of instruments were temporary not available with frequency mean of 2.1 (Minimum: 1; Maximum: 7) whilst 6 types of materials were temporary not available with a frequency mean of 2.3 (Minimum: 1; Maximum: 8). In conclusion, majority of the instruments and materials required during orthodontic clinical sessions were available. The check list of frequently used orthodontic instruments and materials from this audit could aid inventory and help future management of the material and instruments.

Bioactive Glass Coating of Orthodontic Material for the Recovery of Mechanical Properties of Etched Enamel

Bioactive Glass Coating of Orthodontic Material for the Recovery of Mechanical Properties of Etched Enamel

Changes in physical properties of new, non-BPA containing, polymeric orthodontic bracket materials over time: A 2-year clinical study

PurposeThe purpose of this study was to develop new, biocompatible plastic brackets which are esthetic and do not release bisphenol A (BPA). Materials and methodsIn this study, brackets were fabricated using four different materials: polyacetal (POM), polyester (PE) and polycarbonate (PC), and a filled polycarbonate (PCF) as a control. Clinical testing using 46 subjects was conducted to evaluate changes in their physical properties (fracture frequency of bracket wings, strength of bracket wings and bracket wear) over 2 years (at baseline, year 1 and year 2) to assess the suitability of these materials for clinical use. Results(1) PE brackets were the only group that showed fracture in the fracture frequency test. (2) POM showed low wear rates. (3) POM showed great variation in bracket wing strength, but no statistical significant difference was observed between PE and POM. ConclusionThis 2-year clinical study concludes that POM and PE are more promising materials for the fabrication of orthodontic brackets than PCF.

Level of residual monomer released from orthodontic acrylic materials

To quantify, with high-pressure liquid chromatography (HPLC), the amount of residual monomer leached from different orthodontic acrylic materials prepared with two different manipulation methods. Eighty cylindrical specimens (5 × 25 mm) were divided into eight groups (n = 10). The specimens were prepared with four acrylic materials-Orthocryl Neon Blue (Dentaurum), Orthocryl EQ (Dentaurum), Orthoplast (Vertex), and O-80 (Imicryl)-and with two different manipulation methods: doughing and spray-on. HPLC measurements were made at intervals of 2 hours, 6 hours, 1 day, 1 week, and 3 months. One-way analysis of variance (ANOVA) and Tukey's honestly significant difference multiple-comparison test were used to assess the amount of monomer eluted from the various groups. To assess the differences within each group over the various periods, repeated-measures ANOVA and paired t-tests were used. Statistically significant differences were found within the groups in the amount of residual monomer in the specimens at different time intervals (P < .001). HPLC showed statistically significant differences among the groups (P < .05) in the amount of eluted monomer. Evaluation of the manipulation techniques showed that the monomer release rate was higher in the specimens prepared with the doughing method. When the four acrylic materials were compared, the specimens made from Orthoplast (Vertex) showed the highest rate of monomer release with both manipulation techniques. The spray-on method can be recommended to clinicians for the preparation of orthodontic appliances.

Allergic Contact Stomatitis From Orthodontic Adhesives

While allergic contact dermatitis to orthodontic materials is most commonly associated with metals, other materials may also trigger reactions. This report describes an unusual case of contact stomatitis secondary to orthodontic etching and bonding products.

Ligature (Pre Adjusted Edge-wise Appliances) Making Simplified in Orthodontics: Education Pearls

The buccal archwire used in the pre-adjusted edgewise appliances technique is anchored to the brackets by means of ligatures made of soft stainless steel wire of about 0.010 inch diameter. These ligatures are seated under the flanges of the brackets. Various methods have been advocated seating and tying the ligatures. The performed ligatures used in this method differ from those conventionally used in that they can easily and quickly be formed on a jig constructed from available orthodontic material.

Evaluation of oxidative stress biomarkers in patients with fixed orthodontic appliances.

Aim. The aim of this study was to examine the changes in the levels of interleukine-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), malondialdehyde (MDA), nitric oxide (NO), and 8-hydroxydeoxyguanosine (8-OHdG) in saliva and IL-1β, TNF-α, and NO in gingival crevicular fluid (GCF) samples of patients with fixed orthodontic appliances. Material and Method. The subject population consisted of 50 volunteers who were in need of orthodontic treatment with fixed orthodontic appliances. GCF and saliva samples were obtained from all individuals before treatment, at 1st month of treatment and at 6th month of treatment. Periodontal clinical parameters were measured. Samples were investigated to detect IL-1β, TNF-α, and 8-OHdG levels using ELISA method and NO and MDA levels using spectrophotometric method. Results. Since IL-1β level detected in GCF at the 6th month of orthodontic treatment is statistically significant according to baseline (P < 0.05), all other biochemical parameters detected both in saliva and in GCF did not show any significant change at any measurement periods. Conclusion. Orthodontic tooth movement and orthodontic materials used in orthodontic treatment do not lead to a change above the physiological limits that is suggestive of oxidative damage in both GCF and saliva.

Real-time cell analysis of cytotoxicity of orthodontic cements on gingival fibroblasts

Introduction: To evaluate the cytotoxicity of four different orthodontic cement materials using the real-time xCELLigence system. Materials and Methods: Four orthodontic glass ionomer cements (GICs) were selected for this study, namely: GC Fuji (GC Cooperation), Ultra Band Lok (Reliance), Multi Cure (3M Unitek), and Meron (Voco). Ten test cylinders (measuring 5 Χ 2 mm) of each material were fabricated, making a total of 40 cylinders. The samples were incubated in Dulbecco modified Eagle medium (DMEM) culture medium for 72 hours. Human gingival fibroblasts (HGFs) were maintained with DMEM containing 10% fetal bovine serum. A real-time cell analyzer (RT-CES, xCELLigence) was used to evaluate cell survival. After seeding 200 μL of the cell suspensions into the wells (10,000 cells/well), gingival fibroblasts were treated with bioactive components released from cement materials and were monitored every 15 minutes for a period of 88 hours. For proliferation experiments, the statistical analyses used were one-way analysis of variance (ANOVA) and Tukey-Kramer multiple comparisons tests. Results: When the data were evaluated at 24 and 48 hrs, all tested materials showed statistically significant decreases in HGF cell index compared to the control group (P < 0.001). Conclusion: According to the results of this study, all tested cements were found to have cytotoxic effects to the HGFs.

Effect of orthodontic brackets and different wires on radiofrequency heating and magnetic field interactions during 3-T MRI

To evaluate the heating and magnetic field interactions of fixed orthodontic appliances with different wires and ligaments in a 3-T MRI environment and to estimate the safety of these orthodontic materials. 40 non-carious extracted human maxillary teeth were embedded in polyvinyl chloride boxes, and orthodontic brackets were bonded. Nickel-titanium and stainless steel arch wires, and elastic and stainless steel ligaments were used to obtain four experimental groups in total. Specimens were evaluated at 3 T for radiofrequency heating and magnetic field interactions. Radiofrequency heating was evaluated by placing specimens in a cylindrical plastic container filled with isotonic solution and measuring changes in temperature after T1 weighted axial sequencing and after completion of all sequences. Translational attraction and torque values of specimens were also evaluated. One-way ANOVA test was used to compare continuous variables of temperature change. Significance was set at p < 0.05. None of the groups exhibited excessive heating (highest temperature change: <3.04 °C), with the maximum increase in temperature observed at the end of the T1 weighted axial sequence. Magnetic field interactions changed depending on the material used. Although the brackets presented minor interactions that would not cause movement in situ, nickel-titanium and stainless steel wires presented great interactions that may pose a risk for the patient. The temperature changes of the specimens were considered to be within acceptable ranges. With regard to magnetic field interactions, brackets can be considered "MR safe"; however, it would be safe to replace the wires before MRI.

An investigation into bisphenol-A leaching from orthodontic materials

To quantitatively determine the bisphenol-A (BPA) leached from orthodontic materials during simulated intraoral exposure. Samples of orthodontic materials were subjected to simulated abrasion, immersion in artificial saliva, thermal shock via temperature cycling, and simulated intraoral exposure. Sample aliquots were collected for up to 2 weeks after artificial saliva immersion, derivatized, then analyzed for BPA by gas chromatography/mass spectroscopy. Quantifiable amounts of leached BPA were observed from a thermoformed orthodontic retainer material (7.63 µg/g of material) and an orthodontic adhesive (2.75 µg/g of material). BPA leaching was only observed within the first 3 days of artificial saliva immersion. Under the test conditions, BPA was observed to leach from two orthodontic materials. While the quantities of leached BPA were below the reference dose for daily intake, existing data of low-dose effects and medical disorders associated with elevated urinary BPA levels suggest that BPA exposure, and thus the use of the leaching materials identified in this study, should be reduced or eliminated.

Biocompatibility Improvement of NiTi Orthodontic Wire from Various Coatings

NiTi alloy is one of important materials in orthodontics. Shape memory effect of this material ensures the possibility to deliver highly desireable light forces for thooth movement. Unfortunately, NiTi has problem in the high amount content of Ni that can cause allergy or even risk of poisioning in the human body due to Ni ion released. To overcome this problem, several methods of coatings were performed to prevent the releasing of Ni ion. They were Electropolishing Pretreatment combined with Photo Electrocatalytic Oxidation, TiN Pack Cementite, Advanced Oxidation Process and Biomimetic Hidroxyapatite. The objective of this research was to analyze the effect of various coatings to the biocompatibility of orthodontic wire. Biocompatibility of coated NiTi wire was investigated through MTT assay using BHK-21 fibroblast cell in order to analyze the toxicity of each coating method. In addition, the surface roughness was determined using Atomic Force Microscope (AFM). Furthermore, the attachment and spreading of fibroblast cell were observed by Scanning Electron Microscope (SEM). The result was revealed that biomimetic HA coating has the highest cell viability percentage due to its surface morphology.

Biocompatibility Improvement of NiTi Orthodontic Wire from Various Coatings

NiTi alloy is one of important materials in orthodontics. Shape memory effect of this material ensures the possibility to deliver highly desireable light forces for thooth movement. Unfortunately, NiTi has problem in the high amount content of Ni that can cause allergy or even risk of poisioning in the human body due to Ni ion released. To overcome this problem, several methods of coatings were performed to prevent the releasing of Ni ion. They were Electropolishing Pretreatment combined with Photo Electrocatalytic Oxidation, TiN Pack Cementite, Advanced Oxidation Process and Biomimetic Hidroxyapatite. The objective of this research was to analyze the effect of various coatings to the biocompatibility of orthodontic wire. Biocompatibility of coated NiTi wire was investigated through MTT assay using BHK-21 fibroblast cell in order to analyze the toxicity of each coating method. In addition, the surface roughness was determined using Atomic Force Microscope (AFM). Furthermore, the attachment and spreading of fibroblast cell were observed by Scanning Electron Microscope (SEM). The result was revealed that biomimetic HA coating has the highest cell viability percentage due to its surface morphology.

Properties of Composite Materials Used for Bracket Bonding

The purpose of this study was to evaluate in vitro the shear bond strength to enamel, flexural strength, flexural modulus, and contraction stress of one orthodontic composite and two flowable composites. Orthodontic brackets were bonded to 45 human maxillary premolars with the composites Transbond XT, Filtek Z-350 flow and Opallis flow and tested for shear bond strength. For measurement of flexural strength and flexural modulus, specimens were fabricated and tested under flexion. For the contraction stress test, cylindrical specimens were tested and an extensometer determined the height of the specimens. The data were subjected to one-way ANOVA and Tukey's test (α=0.05). The shear bond strength values were significantly lower (p<0.05) for the flowable composites compared with the orthodontic composite. For the flexural strength, no statistically significant difference was found among the composites (p>0.05) while the flexural modulus was significantly higher (p<0.05) for Transbond XT than for Filtek Z-350 flow and Opallis flow. The orthodontic composite presented significantly lower contraction stress values than the flowable composites (p<0.05). The light-activated orthodontic composite material presented higher flexural modulus and shear bond strength and lower contraction stress than both flowable composites.

Electrochemical behavior of CoCrMo implant in Ringer's solution

CoCrMo has been successfully employed as an orthopedic and orthodontic material because of its excellent corrosion resistant and suitable biocompatibility. The purpose of this research was to investigate the susceptibility of CoCrMo in Ringer's solution at three different temperatures: 22 °C, 37 °C, and 60 °C. The corrosion behavior of CoCrMo was carried out by using common electrochemical methods such as open circuit potential, potentiodynamic measurement, electrochemical impedance spectroscopy (EIS), and Mott–Schottky measurements. CoCrMo was passivated by the air, forming a passive film, which was not destroyed during the immersion in electrolytes under different temperatures. Results from potentiodynamic tests showed that at high anodic potentials, the passive film did not demonstrate significant localized corrosion and rather exhibited overall passive film degradation corresponding to the general corrosion of the alloy in Ringer's solution at the three temperatures. EIS measurements showed the presence of the stable passive film on the alloy surface when tested at open circuit potential. Mott–Schottky test indicated that the preformed passive film is an n‐type semiconductor due to the presence of a donor species. This is implied by the existence of oxygen vacancies and interstitial metallic cations. As the potential increased, the Cr3+ oxidized and produced soluble Cr4+ species. This resulted in the film changing to a p‐type semiconductor owing to the dissolution and creation of cation vacancies (acceptor species). The passive film rupture was not due to p‐type characteristics but rather was a result of the considerable oxidative dissolution of the film at high anodic potential. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Accidental ingestion of orthodontic band loop

Any object routinely placed into or removed from the oral cavity during dental or surgical procedures can be aspirated or swallowed. Handling of small instruments or appliances requires special care, particularly when the patient is supine or semi-supine. Prevention of such incidence by the mandatory use of precautions during all dental procedures is the best approach. This case report describes an accidental swallowing of a piece of orthodontic band material and its management, and up-to-date knowledge on prevention and management of foreign body ingestion. Clinical Relevance: Many complications can arise during regular dental care procedures. Aspiration or ingestion of foreign bodies has the potential of resulting in acute medical and life-threatening emergencies as it can be a cause of accidental death. Also, in supine or semi-supine patients, the risk of aspiration or ingestion is increased. Readers should understand that aspiration or ingestion of foreign bodies is a significant medical emergency and should keep themselves updated on how to avoid and manage such an emergency.