The Frictional Behavior of Coated Guiding Archwires

BACKGROUND: The vast range of orthodontic wires made of different alloys makes it increasingly difficult for orthodontists to judge them. Coated orthodontic wires form a group of innovative guiding archwires. MATERIAL AND METHODS: In the present in vitro study the frictional behavior of eight coated wires of different dimensions was investigated in archwire-guided canine retraction in the upper jaw. For this purpose five superelastic nickel titanium alloy wires (Titanol Low Force River Finish Gold and Gold 2: Forestadent, Pforzheim Germany; Titanol Superelastic tooth colored: Forestadent, Pforzheim Germany; BioForce Sentalloy Ionguard: GAC, Central Islip, NY, USA; NITI Imagination: GAC, Central Islip, NY, USA), two beta-titanium wires (TMA Low Friction Ionguard: Ormco, Glendora, CA, USA; TMA Low Friction Ionguard Purple: Ormco, Glendora, CA, USA), and one steel wire (Stainless steel Imagination: GAC, Central Islip, NY, USA) were selected. The coatings were made of Teflon or polyethylene, and by ion implantation. Three uncoated archwires (Rematitan Lite Dimple: Dentaurum, Pforzheim, German; Titanol Low Force River Finish: Forestadent, Pforzheim, Germany; BioForce Sentalloy: GAC, Central Islip, NY, USA) were used for comparison purposes. The force losses due to friction were measured using the Orthodontic Measurement and Simulation System (OMSS). RESULTS: The results indicated that all coatings can reduce frictional losses compared with an uncoated reference wire by the same manufacturer. Measured frictional losses ranged from 48.3-6.1%, with the Teflon coatings reducing the frictional losses to less than 10% in some cases. CONCLUSION: An unequivocal correlation between the surface roughness and frictional forces of the wires could not be verified by scanning electron microscopy.     

On the In Vitro Biocompatibility of Elgiloy?, a Co-based Alloy, Compared to Two Titanium Alloys

Aim: The aim of the present investigation was to contribute to an understanding of the effects of surface topography and chemical composition on the corrosion behavior and thus the biocompatibility of Elgiloy^® (RMO, Denver, CO, USA), a common Co-based alloy. Material and Methods: The results are compared with those obtained for a binary NiTi alloy, Neo Sentalloy™ (GAC, Central Islip, NY, USA) and a #-III-Ti alloy, TMA^® (Ormco, Glendora, CA, USA). In the present study, the surface topography and the chemical composition of two different grades of Elgiloy^®, Blue Elgiloy^® (soft) and Yellow Elgiloy^® (ductile), were examined by means of scanning electron microscopy (SEM) and energy-dispersive spectroscopy analysis (EDS). Their corrosion behavior in half-strength Ringer solution and in an artificial saliva solution according to Barrett [1] was investigated using potentiodynamic corrosion testing (PDC). The photometry-based PAN method was used to quantify the released Ni and Co ions. The in vitro biocompatibility of the two grades of Elgiloy^® was tested in three different cell cultures: in L929, a commercially available mouse fibroblast cell line, and in primary human epithelial cells and fibroblasts. Results: The results of the corrosion testing showed satisfactorily high pitting corrosion potentials but lower repassivation potentials and a strong increase in current density once pitting had occurred. The photometric results revealed the release of Ni and Co ions in both tested electrolytes. The tested native surfaces exhibited numerous grinding and polishing grooves, inclusions and inhomogeneities of the microstructure. After corrosion testing the same surfaces displayed numerous signs of corrosion, especially in areas with microstructural inhomogeneities. In vitro biocompatibility testing showed a substantially reduced dehydrogenase activity in the presence of Elgiloy^®. The reduced quality of surface finish resulting from the manufacturing process led in the case of the tested Elgiloy^® types to decreased corrosion resistance with consequently reduced in vitro biocompatibility. Conclusions: In this context it is also conceivable that patients with a proven allergy to nickel, cobalt or chromium may react sensitively to the deployment of this alloy, at least in the surface quality tested by us. From this aspect, the introduction of a binding standard for the surface quality of materials used in orthodontic appliances is urgently recommended. Zusammenfassung. Ziel: Ziel der Studie ist es, den Zusammenhang zwischen der chemischen Zusammensetzung, Oberflächenmikrostruktur und der Korrosionsbeständigkeit sowie der daraus folgenden In-vitro-Bioverträglichkeit einer gängigen Kobaltbasislegierung in zwei unterschiedlichen Härtegraden von Elgiloy^® (RMO, Denver, CO, USA), Blue Elgiloy^® (soft) and Yellow Elgiloy^® (ductile), herzustellen. Material und Methoden: Zum Vergleich werden die Ergebnisse einer Nickeltitanlegierung, Neo Sentalloy™ (GAC, Central Islip, NY, USA), und einer Titanlegierung, TMA^® (Ormco, Glendora, CA, USA), herangezogen. Die Oberflächenbeschaffenheit und chemische Zusammensetzung wurden mittels Rasterelektronenmikroskopie (REM) und energiedispersiver Röntgenspektroskopie (EDS) untersucht. Ihr Korrosionsverhalten in halbstarker Ringer-Lösung und in einer Speichelersatzlösung nach Barrett [1] ist in potentiodynamischen Korrosionsversuchen (PDK) ermittelt worden. Die im Korrosionstest freigesetzten Ni- und Co-Ionen sind photometrisch nach der PAN-Methode erfasst worden. Die In-vitro-Bioverträglichkeit beider Elgiloy^®-Sorten ist mittels MTT-Test in drei Zellkulturen - L929, eine Mausfibroblastenlinie sowie primären humanen Fibroblasten und Epithelzellen - ermittelt worden. Ergebnisse: Die Ergebnisse der Korrosionsuntersuchungen zeigen zwar zufriedenstellend hohe Lochfraßpotentiale, aber niedrigere Repassivierungspotentiale sowie einen starken Anstieg der Stromdichte nach Beginn der Lochfraßkorrosion. In photometrischen Untersuchungen der verwendeten Elektrolyte konnten freigesetzte Ni- und Co-Ionen nachgewiesen werden. Die untersuchten nativen Oberflächen weisen zahlreiche Schleif- und Polierspuren, Einschlüsse sowie Inhomogenitäten in der Mikrostruktur auf. Die den Korrosionsversuchen ausgesetzten Oberflächen lassen zahlreiche Korrosionserscheinungen erkennen, die bevorzugt in Bereichen intermetallischer Phasen auftreten. In-vitro-Bioverträglichkeitsuntersuchungen zeigen in Anwesenheit von Elgiloy^® eine deutlich herabgesetzte Dehydrogenaseaktivität. Eine durch den Herstellungsprozess bedingte herabgesetzte Güte der Oberflächenqualität führt im Fall der untersuchten Elgiloy^®-Sorten zu einer verminderten Korrosionsresistenz. Dieses wiederum ist die Ursache für einen Rückgang der In-vitro-Bioverträglichkeit. Schlussfolgerungen: In diesem Zusammenhang ist es auch denkbar, dass Patienten mit nachgewiesener Ni-, Co- oder Cr-Allergie empfindlich auf den Einsatz dieser Legierung, zumindest in der uns vorliegenden Oberflächengüte, reagieren können. Es liegt daher nahe, eine verbindliche Norm für die Oberflächenbeschaffenheit der in der Kieferorthopädie eingesetzten Materialien zu fordern.     

Influence of autoclave sterilization on the surface parameters and mechanical properties of six orthodontic wires

Orthodontic wires are frequently packaged in individual sealed bags in order to avoid cross-contamination. The instructions on the wrapper generally advise autoclave sterilization of the package and its contents if additional protection is desired. However, sterilization can modify the surface parameters and the mechanical properties of many types of material.The aim of this research was to determine the influence of one of the most widely used sterilization processes, autoclaving (18 minutes at 134 degrees C, as recommended by the French Ministry of Health), on the surface parameters and mechanical properties of six wires currently used in orthodontics (one stainless steel alloy: Tru-Chrome RMO; two nickel-titanium shape memory alloys: Neo Sentalloy and Neo Sentalloy with Ionguard GAC; and three titanium-molybdenum alloys: TMA(R) and Low Friction TMA Ormco and Resolve GAC).The alloys were analysed on receipt and after sterilization, using surface structure observation techniques, including optical, scanning electron and atomic force microscopy and profilometry. The mechanical properties were assessed by three-point bending tests.The results showed that autoclave sterilization had no adverse effects on the surface parameters or on the selected mechanical properties. This supports the possibility for practitioners to systematically sterilize wires before placing them in the oral environment.     

Bond Strength of Various Fluoride-Releasing Orthodontic Bonding Systems Experimental Study

The aim of the study was to compare the shear bound strength of a fluoride-releasing composite resin adhesive (Light Bond^®, Reliance) and a light-cured resin-reinforced glass ionomer cement (Fuji Ortho LC^®, GC America) bonded to extracted teeth under different enamel surface conditions. Forty human premolars were divided at random into 4 groups of 10 specimens. Stainless steel brackets were attached to the enamel surface by 1 of the 4 protocols: 1. Fuji Ortho LC^®, moist non-etched enamel; 2. Fuji Ortho LC^®, moist etched (37% H₃PO₄); 3. Light Bond^®, dry etched (37% H₃PO₄); 4. Light Bond^®, dry etched (Etch & Prime 3.0^®, Degussa). The teeth were stored in deionized water at 37 °C for 48 hours. Shear bond strengths was determined at a crosshead speed of 1 mm/min. The residual adhesive on the enamel surface was evaluated with the modified Adhesive Remnant Index (ARI). Analysis of variance (ANOVA) and Duncan's test were used to compare the 4 groups. Significance was predetermined at p = 0.05. Significant inter-group differences were found (p < 0.0001). The mean SBS (and SD) in MPa were: Group 1: 15.9 (4.7); Group 2: 20.3 (2.5); Group 3: 16.7 (2.6); Group 4: 11.7 (2.5). Glass ionomer cement without etching and composite with Etch & Prime showed adhesive failures at the enamel and good enamel integrity after debonding. The other specimens showed mixed or adhesive fractures at the bracket failure sites. Glass ionomer used on wet tooth surfaces without etching shows a clinically acceptable bond strength with clean separation from the enamel after debonding. Zusammenfassung: Ziel der Arbeit war es, die Haftfestigkeit eines Fluorid freisetzenden Kompositadhäsivs (Light Bond^®, Reliance) und eines lichthärtenden Glasionomerzements (Fuji Ortho LC^®, GC) nach unterschiedlicher Schmelzkonditinierung miteinander zu vergleichen. Hierzu wurden 40 menschliche Prämolaren randomisiert in vier Gruppen von zehn Proben aufgeteilt. Metallbrackets wurden wie folgt auf die Schmelzoberfläche aufgebracht: 1. Fuji Ortho LC^®, Schmelz feucht und ungeätzt; 2. Fuji Ortho LC^®, feucht geätzt (37% H₃PO₄); 3. Light Bond^®, trocken geätzt (37% H₃PO₄); Light Bond^®, trocken geätzt (Etch & Prime 3.0^®, Degussa). Die Zähne wurden in destilliertem Wasser bei 37 °C für 48 Stunden gelagert. Die Scherfestigkeit der geklebten Brackets am Schmelz wurde bei einer Vorschubgeschwindigkeit von 1 mm/min ermittelt. Danach wurde der auf dem Schmelz verbliebene Kleber mit dem modifizierten Adhesive Remnant Index (ARI) bestimmt. Die Varianzanalyse (ANOVA) und der Duncan-Test wurden zum Gruppenvergleich herangezogen. Das Signifikanzniveau wurde auf p = 0,05 festgelegt. Zwischen den Gruppen wurden signifikante Unterschiede ermittelt (p < 0,0001). Die durchschnittliche Haftfestigkeit (und Standardabweichung) in Megapascal betrug bei Gruppe 1: 15,9 (4,7); Gruppe 2: 20,3 (2,5); Gruppe 3: 16,7 (2,6); Gruppe 4: 11,7 (2,5). Sowohl der Glasionomerzement ohne Schmelzätzung als auch das Kompositadhäsiv mit Etch & Prime^®-Konditionierung zeigten einen adhäsiven Bruch an der Schmelzstelle und eine kaum veränderte Schmelzoberfläche nach Abscherung. Die anderen Proben zeigten Mischbrüche oder kohäsive Brüche an der Bracketseite. Auf ungeätzten und feuchten Zahnoberflächen angebrachter kunststoffverstärkter Glasionomerzement zeigte für die klinische Anwendung eine akzeptable Haftfestigkeit und ein sauberes Lösen von der Schmelzoberfläche bei der Bracketentfernung.     

The effect of surface treatment and clinical use on friction in NiTi orthodontic wires.

OBJECTIVES: Since the low friction of NiTi wires allows a rapid and efficient orthodontic tooth movement, the aim of this research was to investigate the friction and surface roughness of different commercially available superelastic NiTi wires before and after clinical use. The surface of all of the wires had been pre-treated by the manufacturer. MATERIALS: Forty superelastic wires (Titanol Low Force, Titanol Low Force River Finish Gold, Neo Sentalloy, Neo Sentalloy Ionguard) of diameter 0.016 x 0.022 in. were tested. The friction for each type of NiTi archwire ligated into a commercial stainless steel bracket was determined with a universal testing machine. Having ligated the wire into the bracket, it could then be moved forward and backwards along a fixed archwire whilst a torquing moment was applied. The surface roughness was investigated using a profilometric measuring device on defined areas of the wire. Statistical data analysis was conducted by means of the Wilcoxon test. RESULTS: The results showed that initially, the surface treated wires demonstrated significantly (p < 0.01) less friction than the non-treated wires. The surface roughness showed no significant difference between the treated and the non-treated surfaces of the wires. All 40 wires however showed a significant increase in friction and surface roughness during clinical use. SIGNIFICANCE: Whilst the Titanol Low Force River Finish Gold (Forestadent, Pforzheim, Germany) wires showed the least friction of all the samples and consequently should be more conservative on anchorage, the increase in friction of all the surface treated wires during orthodontic treatment almost cancels out this initial effect on friction. It is therefore recommended that surface treated NiTi orthodontic archwires should only be used once.     

Torque Transmission between Square Wire and Bracket as a Function of Measurement, Form and Hardness Parameters

The aim of the study was to investigate the influence of cross section, edge geometry and structural hardness on torque transmission between square wire and bracket. For this purpose, 5 different brands of stainless steel square wire in 3 dimensions (0.016" 2 0.016", 0.016" 2 0.022" and 0.017" 2 0.025") were inserted into edgewise brackets with a slot size of 0.018" and loaded with different torques (1 and 3 Ncm). The slot and wire geometries were analyzed by computer on ground specimens before and after loading. In addition, the Vickers hardness and micro-hardness of the unstressed and stressed metal surfaces were determined. While the slot size was very accurately maintained, the wire dimensions deviated downwards by an average of 10%. Torque transmission led to notching and bending-up phenomena on the bracket slot flanks. A torque loading of 3 Ncm increased the torque play of 0.016" 2 0.022" wires by 3.6°, and of 0.017" 2 0.025" wires by 3.7°. In the case of 0.016" 2 0.016" wires, an effective torque transmission was no longer possible. The average Vickers hardness of the wires was 533 kp/mm², and that of the brackets 145 kp/mm². The micro-hardness in the deformation area of stressed internal slot walls increased with increasing load transmissions from 204 to 338 kp/mm². As a result of excessively small wire dimensions and plastic deformation of the brackets, a relatively large torque play occurs. Deformation and notching in the area of the internal slot walls are inconsistent with demands for recycling brackets. A standardization of bracket wire systems stating the actual torque play would be desirable. Zusammenfassung: Ziel der Studie war es, den Einfluss von Querschnittsmaß, Kantengeometrie sowie Gefügehärte auf die Torquedrehmomentübertragung zwischen Vierkantdraht und Bracket zu untersuchen. Dazu wurden Vierkantdrähte aus rostfreiem Stahl von fünf Herstellern in drei Dimensionen (0,016 " 2 0.016", 0,016" 2 0,022" und 0,017" 2 0,025") in Edgewise-Brackets mit dem Slotmaß 0,018" eingebracht und mit unterschiedlichen Drehmomenten (1 und 3 Ncm) belastet. Slot- und Drahtgeometrie wurden vor und nach Belastung an Schliffpräperaten rechnergestützt analysiert. Außerdem wurden die Vickers- und Mikrohärte der unbelasteten und belasteten Metallflächen bestimmt. Während das Bracketlotmaß recht genau eingehalten wurde, wichen die Drahtdimensionen im Mittel um 10% nach unten ab. Drehmomentübertragung führte zu Einkerbungs- und Aufbiegungserscheinungen an den Bracketslotflanken. Eine Drehmomentbelastung von 3 Ncm erhöhte das Torquespiel von 0,016" 2 0,022"-Drähten um 3,6°, von 0,017" 2 0,025"-Drähten um 3,7°. Bei 0,016" 2 0,016"-Drähten war eine wirksame Drehmonentübertragung nicht mehr möglich. Die Vickers-Härte der Drähte betrug im Mittel 533 kp/mm², die der Brackets 145 kp/mm². Die Mikrohärte im Deformationsbereich belasteter Slotinnenwände nahm mit zunehmender Kraftübertragung von 204 auf 338 kp/mm² zu. Infolge zu kleiner Drahtdimensionen und plastischer Deformation der Brackets kommt es zu einem relativ großen Torquespiel. Deformationen und Einkerbungen im Bereich der Slotinnenwände widersprechen der Forderung nach einem Recycling von Brackets. Eine Normung der Bracketdrahtsysteme unter Angabe des tatsächlichen Torquespiels wäre wünschenswert.     

A Prospective Randomized Study of Different Retainer Types

Background and Aim: In recent years, fixed lingual retainers have been gaining importance in relapse prevention. The aim of this prospective, randomized study was to compare different types of fixed retainers used for stabilization of the lower anterior segment with respect to detachment rate, relapse, periodontal and oral hygiene problems, as well as subjective patient discomfort. Patients and Method: Two types of fixed, customized canine-to-canine retainers (attached to six teeth) with wire diameters of 0.0215" and 0.0195" as well as one type of prefabricated canine-and-canine retainer (bonded to two teeth) were investigated in a total of 103 patients. Some retainers wer inserted under dry field conditions using a rubber dam, and the others under relatively dry conditions using cotton rolls. In addition, two types of composite, Heliosit^® and Concise™, were compared. Results: The canine-and-canine retainer displayed an 18% detachment rate, a value significantly lower than the 29% determined for the 0.0195" canine-to-canine retainers. The 0.0215" canine-to-canine retainer had the highest detachment rate (53%). The 37% detachment rate with dry field bonding was slightly higher than the 32% with relatively dry field bonding. Comparison of the composites showed a significantly higher detachment rate for Heliosit^® (73%) than for Concise™ (27%). Plaque accumulation increased with all retainer types in the course of the study, but with no significant inter-group differences. Tooth position with canine-to-canine retainers showed a good degree of stability. The canine-and-canine retainer induced frequent relapse of incisors not bonded to the retainer. In view of their higher rate of subjective discomfort, canine-and-canine retainers were given a significantly poorer rating than their canine-to-canine counterparts. Zusammenfassung Hintergrund und Ziel: In den letzten Jahren gewinnen die Lingualretainer zur Rezidivprophylaxe an Bedeutung. Ziel der Studie war es, prospektiv und randomisiert verschiedene permanente Retainersysteme zur Stabilisierung der Unterkieferfront in Bezug auf Ablöseraten, Rezidive, parodontale und mundhygienische Probleme sowie subjektive Belastungen zu vergleichen. Patienten und Methode: Es wurden zwei an sechs Zähnen adhäsiv befestigte (Sechspunktretainer) der Drahtstärken 0,0215" und 0,0195" und ein konfektionierter, an zwei Zähnen befestigter Retainer (Zweipunktretainer) verwendet. Ein Teil der Retainer wurde unter Kofferdam eingesetzt, ein anderer unter relativer Trockenlegung mit Watterollen. Des Weiteren wurden die Komposite Heliosit^® Orthodontic und Concise™ Orthodontic verglichen. Ergebnisse: Der Zweipunktretainer wies mit 18% eine signifikant geringere Ablöserate auf als der Sechspunktretainer der Drahtstärke 0,0195" mit 29%. Der Sechspunktretainer der Stärke 0,0215" hat mit 53% die höchste Ablöserate. Die Ablösungsrate lag bei absoluter Trockenlegung mit 37% geringfügig höher als bei relativer Trockenlegung mit 32%. Der Vergleich der beiden Komposite ergab eine signifikant größere Ablösungsrate für Heliosit^® (73%) gegenüber Concise™ (27%). Die Plaqueakkumulation nahm bei allen drei Retainertypen im Verlauf der Studie zu ohne signifikante Unterschiede zwischen den einzelnen Retainertypen. Die Zahnstellung blieb bei den beiden Sechspunktretainern weitgehend stabil. Bei dem Zweipunktretainer kam es gehäuft zu Rezidiven der nicht gefassten Schneidezähne. Zweipunktretainer schnitten durch die höhere Angabe subjektiver Beschwerden bei der Fragebogenauswertung zur Patientenbelastung signifikant schlechter ab als Sechspunktretainer.     

自锁托槽对关闭拔牙间隙阶段滑动阻力的影响

目的 比较在牙齿关闭拔牙间隙过程中不同自锁托槽和传统托槽与不锈钢丝组合所产生的滑动阻力。方法 在干燥环境下,分别选择2种自锁托槽(被动Damon^®和主动Tomy^®)和传统托槽的2种结扎方式(橡皮结扎圈和结扎丝)与0.019×0.025英寸不锈钢丝组合,测量严重牙列拥挤患者在拔牙后排齐整平的下颌模型上关闭拔牙间隙阶段的滑动阻力。采用方差分析的方法对各项测量数据进行统计学处理。结果 在关闭拔牙间隙阶段,不同托槽组合、组间的滑动阻力的差异均具有显著的统计学意义(P<0.01),最大静摩擦力和滑动摩擦力由小到大依次为被动Damon组<主动Tomy组<结扎丝结扎组<结扎圈结扎组。结论 在关闭拔牙间隙阶段,被动自锁托槽的滑动阻力明显小于主动自锁托槽的滑动阻力,自锁托槽的滑动阻力明显小于传统托槽的滑动阻力。     

Evaluation of orthodontic friction using a tribometer with alternating movement

It is essential for orthodontists to control the complex phenomenon of friction. The in vitro techniques, usually dynamometers or tensile testing machines, used to measure the frictional resistance between arch wires and brackets are linear and unidirectional and can be criticised because tooth movements, such as tipping and uprighting, as well everyday oral activities, primarily chewing, are not uni-dimensional but more closely resemble the small amplitude oscillatory phenomena known as fretting. We therefore decided to develop a fretting machine not with linear but with alternating movements better suited to evaluate the frictional behaviour of orthodontic bracket-wire combinations. Once we had completed construction of this device, we proceeded to measure the frictional resistance between one stainless steel bracket (MicroArch GAC) and five wires currently used in orthodontics (Two nickel-titanium shape memory alloys: Neo Sentalloy and Neo Sentalloy with Ionguard GAC--Three titanium-molybdenum alloys: TMA and Low Friction TMA Ormco and Resolve GAC). We were able to set up a classification of the wires according to their coefficient of friction, demonstrating the inefficacy of ion implantation and quantifying the increase in the coefficient of friction which occurs when Resolve wires are placed in the oral environment for approximately one year.     

Comparison of mechanical properties of beta-titanium wires between leveled and unleveled brackets: an in vitro study

Background

The objective of this study is to evaluate the force-deflection behavior of beta-titanium alloy wires between two leveled and unleveled bracket alignment scenarios using a three-point bending test.

Methods

Six groups of ten beta-titanium alloy wire segments (0.017 × 0.025-in. diameter) of different manufacturers (Orthometric, Ortho Organizers, GAC, Morelli, and Ormco) were used. Both brackets were bonded to an acrylic jig with a 10-mm interbracket distance. A 1-mm deflection test in two hypothetical conditions (with aligned brackets and by simulating a 2-mm horizontal displacement of the brackets) was explored. Forces of activation and deactivation of the wires during both tests were compared by an analysis of variance (ANOVA) tests followed by a Tukey test.

Results

A statistically significant difference was found in the force-deflection behavior between some of the wires in both simulated in vitro conditions. For the leveled-type alignment scenario, the differences between wires were up to 70 g (range 110 to 179 g). For the unleveled-type alignment scenario, these differences were up to 65 g (range 111 to 175 g).

Conclusions

The study showed some significant differences in forces generated during activation and deactivation among the five types of beta-titanium wires tested. In comparing leveled and unleveled brackets during activation, only Orthometric Beta Flexy and Ormco Beta-titanium were different between them.     

Comparison of static friction and surface topography of low friction and conventional TMA orthodontic arch wires: An in-vitro study

BackgroundArch wire surface characteristics, especially surface roughness and topography, influence the coefficient of friction during sliding. The clinician should be familiar with the properties of orthodontic appliances and materials that could result in high friction to maximize the efficiency of treatment. This study aimed to compare the static friction of orthodontic arch wire materials, including a newly introduced low-friction TMA, conventional TMA, and stainless steel arch wires, using an Instron universal testing machine and to evaluate their surface topographical features using a noncontact optical profilometer.MethodsA total of 30 arch wire specimens were used, including 10 low-friction TMA (TMA-Low), 10 conventional TMA (TMA-C), and 10 stainless steel (SS), (Ormco, Orange, CA, USA) measuring 0.016 × 0.022 in. The static frictional force of each arch wire material was measured using the universal Instron machine. The surface topography was evaluated using a noncontact profilometer machine.ResultsThe static frictional resistance forces were highest in the TMA-C alloy group, and the value was statistically significant in comparison to the SS arch wire but not to the TMA-Low arch wire. The mean value of the static friction of the TMA-Low group was intermediate between the TMA-C and SS arch wires. However, this difference was statistically insignificant compared to the other two alloys. A surface roughness evaluation using a profilometer machine revealed that the highest mean of all three roughness parameters was found in the TMA-C group, followed by the TMA-Low and SS arch wires in descending order.ConclusionThe static friction resistance forces and surface roughness values of the TMA-Low arch wire are comparable to those of TMA-C but are still considered inferior to those of the SS arch wire.     

Lingual Orthodontics (Part 3): Intraoral Sandblasting and Indirect Bonding

Bracket loss is a severe complication in the course of orthodontic treatment, especially when using lingual appliances. High adhesive strength between bracket and tooth is therefore an important requirement for the successfull integration of lingual orthodontics into everyday practice. The present article examines the influence of intraoral sandblasting prior to etching on the adhevise strength of indirect bonding. The shear bond strength of 20 cylinders made of composite were measured 24 hours after these had been bonded onto the enamel of bovine teeth. The enamel was prepared by sandblasting (Microetcher^®, 50 7m AI₂O₃) for 3 seconds prior to bonding, followed by 30 seconds of enemal etching with 37% phosphoric acid. Twenty specimens were tested without sandblasting in the control group. The results show that intraoral sandblasting prior to etching can significantly (p < 0.001) increase the adhesive strength between enamel and bonding material. Thus intraoral sandblasting is an integral part of the indirect bonding record described in the second section of this article. Zusammenfassung: Der Verlust eines Brackets stellt besonders in der Lingualtechnik eine erhebliche Komplikation im Behandlungsablauf dar. Hohe Verbundfestigkeiten zwischen Bracket und Zahnoberfläche sind daher eine wichtige Voraussetzung für die erfolgreiche Integration der Lingualtechnik in die tägliche Praxis. Die vorliegende Arbeit untersucht den Einfluss des intraoralen Sandstrahlens vor der Säureätzung auf die resultierende Verbundfestigkeit bei einer indirekten Klebung. Dazu wurden die Biegebruchfestigkeiten von 20 indirekt hergestellten Kunststoffzylindern 24 Stunden nach dem Kleben auf Rinderschmelz gemessen. Der Schmelz wurde vor dem Bekleben drei Sekunden sandgestrahlt (Microetcher^®, 50 7m AI₂O₃) und anschließend für 30 Sekunden mit 37%iger Phosphorsäure angeätzt.Bei der Kontrollgruppe mit ebenfalls 20 Proben wurde auf das Sandstrahlen verzichtet. Die Ergebnisse zeigen, dass durch intraorales Sandstrahlen vor dem Anätzen die Verbundfestigkeit zwischen Schmelz und Komposit bei einer indirekten Klebung signifikant (p < 0,001) erhöht werden kann. Intraorales Sandstrahlen ist damit ein wesentlicher Teil des im zweiten Abschnitt dieses Beitrags vorgestellten indirekten Klebeprotokolls.     

Reliability and Validity of the Digigraph? 100 in Orthodontic Diagnosis

Cephalometric analyses of lateral cephalograms allow important statements to be made on diagnosis and treatment planning. Such radiographs should, however, be taken with a considerable reduction in radiation exposure. With the Digigraph^® 100 (Dolphin Imaging Systems Inc., USA) a cephalometric technique based on distance measurements of emitted sonic signals is now available. This study was aimed at determining the degree to which this procedure can cope with the requirements of reliability and validity in the field of orthodontics. For this purpose 50 volunteers were examined by conventional cephalometry with manual tracing of lateral cephalograms as well as by sonic cephalometry, with Jarabak analysis in both cases. In addition an option was available for reading lateral cephalograms into the Digigraph^® by means of a radiography evaluation program. The 31 evaluated parameters were subjected to modified statistical analysis. Good reliability was recorded in the range between 0.96 and 0.99 for eleven sonic cephalometric measurements, whereas 26 values were between 0.69 and 0.95. The validity was significantly lower in comparison to radiocephalometry. In particular, measurements related to landmarks which were difficult to access or could be only indirectly determined, such as the sella point, the articulare point or the apices of the incisors, proved to be weak points of sonic cephalometry. The device is thus indicated rather in the field of communication with the patient or for intermediate examination without radiation exposure. Cephalometry without radiation exposure would represent decisive progress in orthodontic diagnostics. However, some developmental work on the processing software or even the development of a specific sonic cephalometry which deliberately dispenses with parameters that are difficult to record with this procedure is still needed. Zusammenfassung Die kephalometrische Analyse eines Fernröntgenseitenbildes erlaubt es, für die Diagnostik und Planung einer Behandlung wichtige Aussagen zu machen. Die Anfertigung einer solchen Röntgenaufnahme sollte jedoch unter weitestgehender Reduktion der Strahlenexposition geschehen. Mit dem Digigraph^® 100 (Dolphin Imgaing Systems, USA) steht nun eine auf der Distanzmessung emittierter Schallsignale basierende Kephalometrietechnik zur Verfügung. Ziel dieser Studie war es herauszufinden, inwieweit das Verfahren den Anforderungen an Reliabilität und Validität auf dem Gebiet der Kieferorthopädie zu genügen vermag. Hierzu wurden 50 Probanden konventionell kephalometrisch unter manueller Durchzeichnung der Fernröntgenseitenbilder sowie schallkephalometrisch jeweils nach der Analyse von Jarabak untersucht. Zusätzlich bestand die Option, die Fernröntgenseitenbildaufnahmen mit Hilfe eines Röntgenauswerteprogramms in den Digigraph^® einlesen zu lassen. Die 31 ermittelten Parameter wurden einer modifizierten statistischen Analyse zugeführt. Es ergab sich eine gute Reliabilität im Bereich 0,96 bis 0,99 für elf schallkephalometrische Messungen, während 26 Werte zwischen 0,69 und 0,95 lagen. Die Validität im Vergleich zur Röntgenkephalometrie lag deutlich niedriger. Insbesondere erwiesen sich Maße, die sich auf nur indirekt zu bestimmende oder schwer zugängliche Messpunkte wie den Sellapunkt, den Artikularepunkt oder auch die Zahnwurzelspitzen der Inzisivi beziehen, als Schwachstellen der Schallkephalometrie. Die Indikation des Gerätes ist daher eher im Bereich der Kommunikation mit dem Patienten oder für Zwischenuntersuchungen ohne Strahlenexposition zu sehen. Eine Kephalometrie ohne Strahlenexposition wäre ein entscheidender Fortschritt für die kieferorthopädische Diagnostik. Allerdings bedarf es hierzu noch einiger Entwicklungsarbeit bei der Verarbeitungssoftware oder gar der Entwicklung einer eigenen Schallkephalometrie, die bewusst auf die Einbeziehung mit diesem Verfahren schwierig zu erfassender Parameter verzichtet.     

Klinischer Beitrag zur Molarendistalisation mit superelastischen Drähten

Zusammenfassung Eine Klasse-II/2-Anomalie mit ausgeprägten Engständen wurde ohne Extraktion von Zähnen durch Distalisation korrigiert. Die oberen Molaren wurden mittels superelastischer Bögen nach distal bewegt. Die kieferorthopädische Behandlungsweise wird vorgestellt und die Ergebnisse werden diskutiert. Diese Behandlungsart zeigt ein weiteres Anwendungsgebiet für superelastische Drähte auf.

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A clinical report for distalizing maxillary molars by using super-elastic wires

Summary A class II/2 malocclusion with considerable amount of crowding was treated non-extraction by distalization. The upper molars were moved posteriorly with the use of superelastic wires. The orthodontic therapy-mode is presented and the results are discussed. This treatment approach shows another use of superelastic wires.

     

The Comparison of Reliabilities in Dental Imaging Methods

Objectives: Common practice in the statistical comparison of imaging instruments with limited reproducibility consists in the separate estimation of the instrument's reliabilities. However, as soon as one of the imaging methods is subject to item-specific bias (which has to be expected in many dentomaxillofacial imaging procedures), this approach will end in severe errors in reliability computation and in corresponding erroneous clinical conclusions. This paper seeks to point out these effects and to illustrate a more appropriate model for the comparison of instrumental reliabilities. Methods: A standard reliability model was adjusted for item-specific bias and illustrated by the comparison of twice repeated planimetric cephalometry versus twice repeated noninvasive orthodontic video imaging (based on the Digigraph^® 100 device) in 50 children; the anterior cranial base length was used for illustration. Results: The proposed model revealed pronounced inferiority of the video-based imaging system concerning its reliability compared with the X-ray based standard. Analysis using separate estimation of the two reliabilities would result in the reverse conclusion and thus falsely establish video imaging, which is in fact less reliable, as a superior diagnostic method. Conclusion: The reliabilities of dentomaxillofacial imaging methods have to be adjusted for potential item-specific bias to avoid the erroneous conclusion of the superiority of a diagnostic innovation. Zusammenfassung. Hintergrund: Eine nicht unübliche Praxis bei statistischen Vergleich bildgebender Verfahren von begrenzter Reproduzierbarkeit besteht in der separaten Schätzung der instrumentellen Reliabilitäten. Sobald jedoch die Ergebnisse eines der bildgebenden Verfahren einem Item-spezifischen Bias unterliegen (was für zahlreiche bildgebende Verfahren in der Zahnheilkunde zu erwarten steht), werden bei diesem Vorgehen die Reliabilitäten mitunter massiv verzerrt geschätzt; entsprechende fehlerhafte Schlussfolgerungen können resultieren. Diese tutorielle Arbeit möchte diesen Effekt aufzeigen und ein sachgerechteres Modell zum Vergleich instrumenteller Reliabilitäten illustrieren. Methoden: Ein gängiges Reliabilitätsmodell wird an Item-spezifischen Bias adjustiert und am Vergleich der jeweils zweimal wiederholten röntgenbasierten planimetrischen Kephalometrie mit der nichtinvasiven kieferorthopädischen Videodigitalisierung (auf der Basis des Digigraph^® 100) bei 50 Kindern illustriert. Die vordere Schädelbasislänge wird als exemplarischer klinischer Endpunkt verwendet. Ergebnisse: Das vorgeschlagene statistische Modell erlaubt den Beleg einer merklichen Unterlegenheit des Videosystems gegenüber dem röntgenbasierten Standard hinsichtlich der Reliabilität. Die separate Schätzung der beiden Reliabilitäten würde jedoch den umgekehrten Schluss nahe legen und somit fälschlicherweise die weniger reliable Diagnostik als überlegen darstellen. Schlussfolgerung: Die Reliabilitäten bildgebender Verfahren in der Zahnheilkunde sollten grundsätzlich unter Adjustierung an Item-spezifischen Bias geschätzt werden, um fehlerhafte Schlussfolgerungen hinsichtlich der diagnostischen Überlegenheit eines Novums zu vermeiden.     

Evaluation of the fit of preformed nickel titanium arch wires on normal occlusion dental arches

Aim

To determine the fits of preformed nickel titanium (NiTi) archwires on dental arches with normal occlusion.

Methods

Forty sets of upper and lower plaster models were obtained from men and women with Class I occlusions. Preformed 0.016″ × 0.022″ NiTi archwires from Rocky Mountain Orthodontics (RMO), 3 M Unitek, Ormco, and Dentaurum were evaluated in terms of their fits on dental arches from male, female, and combined cases. Data were analyzed by using fourth- and sixth-order polynomial equations, analysis of variance (ANOVA), and the Duncan post hoc test.

Results

In the upper arches, the best fit and least error were obtained with RMO Ovoid and Ormco Orthos Large archwires for male cases, but with 3 M Orthoform LA archwires for female and combined cases. In the lower arches, the best fit and least error were obtained with Ormco Orthos Large for male cases, with 3 M Orthoform LA and RMO Normal for female cases, and with 3 M Orthoform LA, RMO Normal, Ormco Orthos Large, and Ormco Orthos Small for combined cases. When both dental arches were matched, Ormco Orthos Large was the best wire for male cases. 3 M Orthoform LA was the best wire for female and combined cases.

Conclusions

Using an archwire form with the best fit to the dental arch should produce minimal changes in the dental arch form when NiTi wires are used and require less customization when stainless-steel wires are used.     

Characterization of the coatings covering esthetic orthodontic archwires and their influence on the bending and frictional properties

Objective:To analyze the coatings covering esthetic orthodontic wires and the influence of such coatings on bending and frictional properties.Materials and Methods:Four commercially available, coated esthetic archwires were evaluated for their cross-sectional dimensions, surface roughness (R_a), nanomechanical properties (nanohardness, nanoelastic modulus), three-point bending, and static frictional force. Matched, noncoated control wires were also assessed.Results:One of the coated wires had a similar inner core dimension and elasticity compared to the noncoated control wire, and no significant differences between their static frictional forces were observed. The other coated wires had significantly smaller inner cores and lower elasticity compared to the noncoated wires, and one of them showed less static frictional force than the noncoated wire, while the other two coated wires had greater static frictional force compared to their noncoated controls. The dimension and elastic modulus of the inner cores were positively correlated (r = 0.640), as were frictional force and total cross-sectional (r = 0.761) or inner core (r = 0.709) dimension, elastic modulus (r = 0.777), nanohardness (r = 0.802), and nanoelastic modulus (r = 0.926). The external surfaces of the coated wires were rougher than those of their matched controls, and the R_a and frictional force were negatively correlated (r = −0.333).Conclusions:Orthodontic coated wires with small inner alloy cores withstand less force than expected and may be unsuitable for establishing sufficient tooth movement. The frictional force of coated wires is influenced by total cross-section diameter, inner core diameter, nanohardness, nanoelastic modulus, and elastic modulus.     

Shear bond strength of an experimental composite bracket

Objective

The in vitro shear bond strength of MZ100 brackets (an experimental composite bracket developed by the Dental Biomaterial Laboratory at Boston University) and the effect of different treatment methods on these brackets were evaluated.

Materials and methods

As the bonding substrates, 80 Vitablocs® Mark II (Vident, Brea, CA, USA) were chosen. Three treatment methods were employed on 60 MZ100 bracket bases (20 brackets per treatment): silane coupling agent (Porcelain Primer; Ormco, Orange, CA, USA), sandblasting (Basic Professional Model Sandblaster; Renfert GmbH, Germany), and non-treatment. Two different orthodontic adhesives were also used: Blugloo? (Ormco, Orange, CA, USA) and Enlight? (Ormco, Orange, CA, USA). Twenty metal brackets were used as controls. Shear bond strength tests were performed after sample preparation and bracket bonding.

Results

The mean shear bond strength of non-treated MZ100 brackets bonded with Enlight? had the lowest value (7.9 MPa), while that of sandblasted MZ100 brackets bonded with Blugloo? showed the highest value (17.9 MPa). The mean shear bond strength of non-treated MZ100 brackets was significantly lower than that of the other groups (p<0.05). The mean shear bond strength of sandblasted MZ100 brackets bonded with Blugloo? was significantly higher than that of those bonded with Enlight? (p<0.05). With the exception of the silane–Blugloo? group, the treated MZ100 brackets demonstrated shear bond strengths that did not significantly differ from metal brackets.

Conclusion

The use of sandblasting and silane coupling agent significantly increases the shear bond strength of the MZ100 brackets to values resembling those of metal brackets.     

Mechanical properties of different esthetic and conventional orthodontic wires in bending tests

Aims

The goal of this study was to determine the mechanical properties of different esthetic and conventional orthodontic wires in three-point and four-point bending tests, and in a biomechanical test employing three bracket systems.

Methods

The behavior of round wires with a diameter of 0.46 mm (0.018″) were investigated: uncoated nickel titanium (NiTi) wires, surface modified NiTi wires; FLI^® Orthonol Wire^® and glass fiber reinforced plastic wires. The biomechanical bending test was performed using the following bracket types: metal brackets (Discovery^®, Dentaurum), ceramic brackets (Fascination^®, Dentaurum), and plastic brackets (Elegance^®, Dentaurum). All bending tests were performed in the orthodontic measurement and simulation system (OMSS) at a temperature of 37 °C. The classical three-point bending test was performed according to an ISO standard (DIN EN ISO 15841:2007) using the appropriate thrust die and supports with a predefined span of 10 mm. In the other tests the supports or interbracket distances were chosen such that the free wire length was also 10 mm (5 mm between adjacent brackets). All wires were loaded centrally to a maximum of 3.1 and 3.3 mm in the biomechanical test, respectively. The force was measured upon unloading with a loading velocity of 1 mm/min. Each specimen was loaded twice and a total of 10 specimens tested for each product. Weighted means and the error of the weighted mean were calculated for each product.

Results

Fiber reinforced wires displayed lowest forces in three-point bending with values of 0.4 N at a displacement of 1 mm and 0.7 N at a 2 mm displacement. In four-point bending the forces were 0.9 N and 1.4 N, respectively, at the same displacements. Almost all of the translucent wires showed fracture upon bending at displacements greater than 3 mm, independent of the bending test and bracket type. The different investigated NiTi wires, surface modified or conventional, only showed minor variation, e.g., 2.2 N for rematitan^® Lite White and 2.0 N for rematitan^®, 2.1 N for FLI^® Coated Orthonol^® and 1.7 N for Orthonol^® in four-point bending. The rhodinized wire generated forces between these values (2.1 N).

Conclusion

The translucent wires had the lowest forces in all three bending tests; however, displacements above 3 mm resulted in increased risk of fracture. Forces of investigated NiTi wires were very high and in part above clinically recommended values.

     

Role of lubricants on friction between self-ligating brackets and archwires

Objective:To evaluate the effect of different lubricants on friction between orthodontic brackets and archwires.Materials and Methods:Active (Quick, Forestadent) and passive (Damon 3MX, Ormco) self-ligating brackets underwent friction tests in the presence of mucin- and carboxymethylcellulose (CMC)–based artificial saliva, distilled water, and whole human saliva (positive control). Dry friction (no lubricant) was used as the negative control. Bracket/wire samples (0.014 × 0.025 inch, CuNiTi, SDS Ormco) underwent friction tests eight times in a universal testing machine.Results:Two-way analysis of variance showed no significant interaction between bracket type and lubricant (P  =  .324). Friction force obtained with passive self-ligating brackets was lower than that for active brackets (P < .001). Friction observed in the presence of artificial saliva did not differ from that generated under lubrication with natural human saliva, as shown by Tukey test. Higher friction forces were found with the use of distilled water or when the test was performed under dry condition (ie, with no lubricant).Conclusion:Lubrication plays a role in friction forces between self-ligating brackets and CuNiTi wires, with mucin- and CMC-based artificial saliva providing a reliable alternative to human natural saliva.