Ludger Keilig

Nickel concentration in the saliva of patients with nickel-titanium orthodontic appliances.

INTRODUCTION The purpose of this study was to examine whether nickel-titanium (Ni-Ti) archwires cause an increase of nickel concentration in the saliva of 18 orthodontic patients to estimate the possible risk of these archwires in patients who have nickel hypersensitivity. METHODS Saliva samples were collected before orthodontic treatment, after placement of the bands and brackets, 2 weeks later and before placing the Ni-Ti archwires, immediately after placing the Ni-Ti archwires, 4 weeks after placing the wires, and 8 weeks after placing the wires. RESULTS By using mass spectrometry, no statistically significant differences were found in the nickel concentrations in the samples taken without appliances, in those obtained 2 weeks after placement of the bands and brackets, and 4 and 8 weeks after placement of the archwires. Samples taken immediately after placement of the bands and brackets and the Ni-Ti archwires showed slight but significant increases in nickel concentration of 78 and 56 microg per liter, respectively, compared with the pretreatment value of 34 microg per liter. CONCLUSIONS Nickel leaching occurred after placement of the bands and brackets and after placement of the Ni-Ti archwires, associated with an increase of the nickel ion concentration in the patients saliva. This effect decreased within 10 weeks.

Numerical analyses of biomechanical behavior of various orthodontic anchorage implants.

Objective:The quality and quantity of the alveolar process are considered important influential factors affecting the anchorage effectiveness of orthodontic mini-implants. The objective of this study was to establish the effect of various material parameters in regard to various implant types, sizes, and load directions using the finite element method (FEM).Materials and Methods:FE models of the following 16 implants by six different manufacturers were made in idealized jaw bone segments with the program system MSC.Marc/Mentat: Åarhus Mini-Implant (American Orthodontics), AbsoAnchor® (Dentos), Dual-Top™ (Jeil Medical), LOMAS (Mondeal), OrthoImplant (IMTEC), tomas® (Dentaurum). The intra-osseous parts of the mini-implants had lengths ranging between 6.7 mm and 10.0 mm, and diameters between 1.2 mm and 2.0 mm. Cortical thicknesses of 1 mm and 2 mm were simulated. The Young’s modulus of cancellous bone was varied between 100 MPa and 1 GPa, the load direction of 0° to 45° in a buccal direction for a load of 5 N. In each case we determined the deflection of the implant head as well as the distribution of stresses and strain in the cortical and cancellous bone.Results:Deflections of the implants varied between 2 μm (Åarhus Mini-Implant 11.6 mm × 2.0 mm, 2 mm cortex) and 20 μm (AbsoAnchor® 12.5 mm × 1.2 mm, 1 mm cortex), the deflection was between 4 μm and 10 μm for most of the implants. The deflections of the implant increased as Young’s modulus of the cancellous bone dropped with a cortical thickness of 1 mm. We did not observe such a correlation with a cortical thickness of 2 mm. We measured the highest loads in the bone in all models when the cortical thickness measured 1 mm and with a Young’s modulus of cancellous bone of 100 MPa. When the load direction was tilted in a buccal direction, the stresses and amount of strain were reduced by as much as 35%.Conclusion:We have demonstrated that the cortical thickness is a decisive parameter for the stability of these mini-implants. When the cortical bone is thinner, the mobility becomes increasingly dependent on the Young’s modulus of the cancellous bone. Moreover, the greatest stress and amount of strain occur in the bone when the cortical bone is less thick and Young’s modulus of cancellous bone lower.ZusammenfassungZiel:Qualität und Quantität des Alveolarknochens gelten als bedeutende Einflussfaktoren auf die Verankerungseffizienz orthodontischer Mini-Implantate. Ziel dieser Untersuchung war es, die Auswirkung unterschiedlicher Materialparameter im Hinblick auf verschiedene Implantattypen und -größen sowie Belastungsrichtungen mit Hilfe der Finite-Elemente-Methode (FEM) zu ermitteln.Material und Methodik:FE-Modelle der folgenden 16 Implantate sechs unterschiedlicher Hersteller wurden in idealisierten Kieferknochensegmenten mit dem Programmsystem MSC.Marc/Mentat erstellt: Åarhus Mini-Implant (American Orthodontics), AbsoAnchor® (Dentos), DualTop™ (Jeil Medical), LOMAS (Mondeal), OrthoImplant (IMTEC) und tomas® (Dentaurum). Der intraossäre Anteil der Mini-Implantate variierte zwischen Längen von 6,7 mm und 10,0 mm, der Durchmesser zwischen 1,2 und 2,0 mm. Es wurden Kortikalisdicken von 1 mm und 2 mm simuliert. Der Spongiosa-Elastizitätsmodul(-E-Modul) wurde zwischen 100 MPa und 1 GPa, die Belastungsrichtung von 0° bis 45° nach bukkal bei einer Last von 5 N variiert. Es wurden jeweils die Auslenkung des Implantatkopfes sowie die Verteilung von Spannungen und Verzerrungen in der Kortikalis und der Spongiosa ermittelt.Ergebnisse:Auslenkungen der Implantate variierten zwischen 2 μm (Åarhus Mini-Implant 11,6 mm × 2,0 mm, 2 mm Kortikalis) und 20 μm (AbsoAnchor® 12,5 mm × 1,2 mm, 1 mm Kortikalis), bei einem Großteil der Implantate lag die Auslenkung zwischen 4 μm und 10 μm. Bei einer Kortikalisdicke von 1 mm stiegen die ermittelten Auslenkungen des Implantates mit sinkendem E-Modul der Spongiosa an. Bei einer Kortikalisdicke von 2 mm konnte dieser Zusammenhang nicht beobachtet werden. Bei allen Modellen konnten für eine Kortikalisdicke von 1 mm und einem Spongiosa-E-Modul von 100 MPa die höchsten Belastungen im Knochen ermittelt werden. Durch das Kippen der Lastrichtung nach bukkal reduzierten sich die Spannungen und Verzerrungen um bis zu 35%.Schlussfolgerung:Insgesamt zeigte sich, dass die Kortikalisdicke ein entscheidender Parameter für die Stabilität der untersuchten Mini-Implantate ist. Bei geringer Dicke nimmt die Beweglichkeit in Abhängigkeit vom E-Modul der Spongiosa deutlich zu. Bei geringer Kortikalisdicke und niedrigem Spongiosa-E-Modul werden dabei die höchsten Spannungen und Verzerrungen im Knochen erreicht.

Corrosion Susceptibility and Nickel Release of Nickel Titanium Wires during Clinical Application

Background and Objective:Orthodontic wires are exposed to a corrosive intraoral environment and are subject to mechanical and thermal load. This could affect how nickel titanium (NiTi) wires corrode, as they possess temperature- and load-dependent characteristics. It was the scope of this study to determine whether the clinical application of NiTi wires would lead to corrosion defects on the wire surfaces, and whether an influence on the patients’ salivary Ni ion concentration would become apparent.Material and Methods:A total of 115 wires of different manufacturers (Forestadent Titanol® ‘Low Force’ und ‘Martensitic’, Ormco Copper Ni-Ti® 35 °C, Ortho Organizers NiTi) was retrieved after intraoral application lasting 1 to 12 months. The wires were examined after cleaning with a scanning electron microscope. We also analyzed the salivary Ni ion concentration in 18 patients at predefined intervals following a detailed orthodontic treatment protocol during the initial phase of orthodontic therapy. The intervals were: 1) a saliva sample before treatment commenced, 2) after bonding of brackets and bands, 3) 2 weeks after bonding, immediately before and 4) immediately after fitting the archwires, and 5) 4 and 6) 8 weeks after placing the archwires. 16 to 20 brackets and bands were bonded in the upper and lower jaws, while NiTi leveling arches (ODS Euro Arch Opto Therm™, 0.40 mm round) were fitted. The saliva samples were quick-frozen and subsequently dried under red light. Dried residuals were dissolved in aqua regia and filled up to 3 ml. The solutions were analyzed using a mass spectrometer (Perkin Elmer Elan 5000).Results:Surface analysis revealed no differences in the degree of corrosion of the different products. In fact, we observed only extremely small and isolated corrosion defects. No statisticallysignificant differences were noted in the Ni ion concentration at time points 1 (reference value), 3, 5 and 6 (34, 34, 28 and 30 μg/l, respectively). The samples taken immediately after bracket bonding or the NiTi wire application however displayed a significant increase in the salivary Ni ion concentration (2: 78 and 4: 56 μg/l). It was significantly higher after bonding of the steel brackets than after NiTi wire application.Conclusions:Increased Ni ions are released initially after the orthodontic devices have been fitted, but they decay quickly. This is reflected in miniscule corrosion defects as pitting. It is unlikely that orthodontic nickel titanium wires are a relevant additional Ni load for the patient.ZusammenfassungHintergrund und Ziel:Orthodontische Drähte sind intraoral nicht nur einem korrosiven Milieu ausgesetzt, sondern unterliegen auch mechanischen und thermischen Belastungen. Dies kann bei Nickel-Titan-(NiTi-)Drähten mit ihren belastungs- und temperaturabhängigen Eigenschaften das Korrosionsverhalten beeinflussen. Im Rahmen dieser Studie wurde daher untersucht, ob der klinische Einsatz von NiTi-Drähten zu Korrosionsdefekten auf der Drahtoberfläche führt und ein Einfluss auf die Nickelionenkonzentration im Speichel der Patienten nachzuweisen ist.Material und Methodik:Insgesamt 115 Drähte verschiedener Hersteller (Forestadent Titanol® ‚Low Force’ und ‚Martensitic’, Ormco Copper Ni-Ti® 35 °C, Ortho Organizers NiTi) wurden nach klinischem Einsatz über eine Zeitdauer von 1 bis zu 12 Monaten gesammelt und die Oberfläche nach Reinigung im Rasterelektronenmikroskop untersucht. Des Weiteren erfolgte bei 18 Patienten, bei denen eine in der Initialphase fest definierte kieferorthopädische Behandlung durchgeführt wurde, eine Analyse der Ni-Ionenkonzentration im Speichel zu bestimmten Zeitpunkten. Diese waren: 1) Speichelprobe als Referenzwert vor Beginn der Behandlung, 2) nach Befestigen der Brackets und Bänder, 3) 2 Wochen danach, unmittelbar vor und 4) unmittelbar nach Einsetzen der Bögen, 5) 4 und 6) 8 Wochen nach Einsetzen der Bögen. Im Ober- und Unterkiefer wurden 16 bis 20 Brackets und Bänder gesetzt, es wurden Nivellierungsbögen aus Nickel-Titan des Fabrikats ODS Euro Arch Opto Therm™ (0,40 mm rund) eingesetzt. Die Speichelproben wurden tiefgekühlt gelagert und anschließend unter Rotlicht getrocknet. Die getrockneten Rückstände wurden mit Königswasser gelöst und auf 3 ml aufgefüllt. Die Lösungen wurden in einem Massenspektrometer (Perkin Elmer Elan 5000) analysiert.Ergebnisse:Die Untersuchung der Drahtoberflächen erbrachte keine Unterschiede im Korrosionsverhalten der unterschiedlichen Produkte. Insbesondere erwiesen sich die auf den Drahtoberflächen festgestellten Korrosionsdefekte als extrem klein und nur vereinzelt auftretend. In Bezug auf die Ni-Ionenkonzentrationen in den Proben konnten zu den Zeitpunkten 1 (Referenzwert), 3, 5 und 6 (34, 34, 28 und 30 μg/l) keine statistisch signifikanten Unterschiede festgestellt werden. Die Proben, die unmittelbar nach dem Einsetzen von Brackets bzw. NiTi-Bögen entnommen wurden, zeigten dagegen jeweils einen signifikanten Anstieg der Ni-Ionenkonzentration (2: 78 und 4: 56 μg/l). Die Ni-Konzentration nach Einsetzen der Stahlbrackets war dabei signifikant höher als die nach Einsetzen der NiTi-Drähte.Schlussfolgerungen:Nach Einsetzen der Apparaturen findet nur initial eine erhöhte Ni-Ionen-Abgabe statt, die nach kurzer Zeit wieder abklingt. Diese äußert sich in extrem kleinen Korrosionsdefekten in Form von Lochfraß auf den Drahtoberflächen. Es ist nicht zu erwarten, dass kieferorthopädische Drähte aus Nickel-Titan eine relevante zusätzliche Ni-Belastung für den Patienten darstellen.

Numeric modeling of torque capabilities of self-ligating and conventional brackets

INTRODUCTION The purpose of this study was to investigate the torque capabilities of conventional and self-ligating brackets by using the finite element method. METHODS Three types of brackets were selected: self-ligating Hanson Speed (Strite Industries, Cambridge, Ontario, Canada) and Damon MX (Ormco, Glendora, Calif), and conventionally ligated Discovery (Dentaurum, Pforzheim, Germany). All brackets had a 0.022-in slot size. From the maxillary left incisor to the maxillary right canine, 4 brackets were included in the finite element models generated. Torque of 20 degrees was applied to the maxillary right incisor with 0.46 x 0.64 mm(2) (0.018 x 0.025 in) and 0.48 x 0.64 mm(2) (0.019 x 0.025 in) archwires. Three kinds of wire alloys were used: stainless steel, titanium molybdenum, and nickel titanium. For the conventional Discovery brackets, 2 types of ligation were modeled: elastic and stainless steel wire ligatures. The torque angle/torque moment characteristics in the simulated movement were calculated by using the MSC.Marc/Mentat 2005 FE software package (MSC Software Corporation, Santa Ana, Calif). RESULTS The torque angle/torque moment curves seemed to be dominated by the characteristics of the wire. The change of wire dimension increased the torque moments less than the change of wire alloy (125% increase for a 0.48 x 0.64 mm(2) instead of a 0.46 x 0.64 mm(2) stainless steel wire, and 220% for a 0.46 x 0.64 mm(2) stainless steel instead of a nickel-titanium wire). The combined change of the wire alloy and wire dimension resulted in a 600% increase for a 0.48 x 0.64 mm(2) stainless steel instead of a 0.46 x 0.64 mm(2) nickel-titanium wire.The play of the 0.46 x 0.64 mm(2) wires was about 9.0 degrees, and the play of the 0.48 x 0.64 mm(2) wires was about 7.5 degrees, with slightly more play for the Damon. The ligation effect of Discovery brackets with elastic and stainless steel ligatures could be compared with the behavior of the Damon. The Speed showed different behavior, with the lowest torquing moments and the smallest torque play. CONCLUSIONS Improving the adaptation of torque movements to the biomechanical reactions of the periodontium is best done by proper selection of both wire dimension and wire alloy. The effect of the bracket system is of minor importance, with the exception of brackets with an active clip (eg, Speed), which had the least play and the lowest torquing moments of all the wires.

3D Reconstruction of dental specimens from 2D histological images and μCT-Scans

Direct comparison of experimental and theoretical results in biomechanical studies requires a careful reconstruction of specimen surfaces to achieve a satisfactory congruence for validation. In this paper a semi-automatic approach is described to reconstruct triangular boundary representations from images originating from, either histological sections or μCT-, CT- or MRI-data, respectively. In a user-guided first step, planar 2D contours were extracted for every material of interest, using image segmentation techniques. In a second step, standard 2D triangulation algorithms were used to derive high quality mesh representations of the underlying surfaces. This was accomplished by converting the 2D meshes into 3D meshes by a novel lifting procedure. The meshes can be imported as is into finite element programme packages such as Marc/Mentat or COSMOS/M. Accuracy and feasibility of the algorithm is demonstrated by reconstructing several specimens as examples and comparing simulated results with available measurements performed on the original objects.

Effect of mini-implant length and diameter on primary stability under loading with two force levels

Mini-implants are widely utilized as anchorage units in orthodontic treatment. Nevertheless, there are factors that interfere with their clinical performance. The aim of this study was to examine the impact of length and diameter on the primary stability of two different types of orthodontic mini-implants loaded with two force levels. A total of 90 self-drilling mini-implants were inserted in bovine ribs in vitro, 62 of which were used in data analysis. The mini-implants were of two types, Aarhus (n=29) and Lomas (n=33), of two lengths (7 and 9 mm, n=26 and n=28, respectively), and of two diameters (1.5 and 2 mm, Lomas only, n=6 and n=8, respectively). A closed nickel-titanium (NiTi) coil spring was attached to each mini-implant. Half of the preparations were loaded with a low force of 0.5 N and the other half with a force of 2.5 N. Mini-implant deflections during force application were non-invasively registered using a three-dimensional (3D) laser-optical system. The results were analysed with analysis of variance for the effects of implant type, implant length, and force level, and with a t-test for the study of the effect of diameter in two different diameter variants of the same (Lomas) implant. In the low-force group, implant displacements were not statistically significant difference according to the investigated parameters. In the high-force group, the 9 mm long mini-implants displaced significantly less (10.5±7.5 μm) than the 7 mm long (22.3±11.3 μm, P<0.01) and the 2 mm wide significantly less (8.8±2.2 μm) than the 1.5 mm implants (21.9±1.5 μm, P<0.001). The force level at which significance occurred was 1 N. The rotation of the Lomas mini-implants in the form of tipping was significantly higher than that of the Aarhus mini-implants at all force levels. Implant length and diameter become statistically significant influencing parameters on implant stability only when a high force level is applied.

Comparative analysis of numerical and experimental data of orthodontic mini-implants

The purpose of this study was to compare numerical simulation data derived from finite element analysis (FEA) to experimental data on mini-implant loading. Nine finite element (FE) models of mini-implants and surrounding bone were derived from corresponding experimental specimens. The animal bone in the experiment consisted of bovine rib. The experimental groups were based on implant type, length, diameter, and angle of insertion. One experimental specimen was randomly selected from each group and was digitized in a microCT scanner. The FE models consisted of bone pieces containing Aarhus mini-implants with dimensions 1.5 × 7 mm and 1.5 × 9 mm or LOMAS mini-implants (dimensions 1.5 × 7 mm, 1.5 × 9 mm, and 2 × 7 mm). Mini-implants were inserted in two different ways, perpendicular to the bone surface or at 45 degrees to the direction of the applied load. Loading and boundary conditions in the FE models were adjusted to match the experimental situation, with the force applied on the neck of the mini-implants, along the mesio-distal direction up to a maximum of 0.5 N. Displacement and rotation of mini-implants after force application calculated by FEA were compared to previously recorded experimental deflections of the same mini-implants. Analysis of data with the Altman-Bland test and the Youden plot demonstrated good agreement between numerical and experimental findings (P = not significant) for the models selected. This study provides further evidence of the appropriateness of the FEA as an investigational tool in relevant research.

Comparative study of four retentive anchor systems for implant supported overdentures – retention force changes

OBJECTIVES Wear of attachments leads to a loss of retention and potentially reduces the function of complete dentures. This study evaluated the retention force changes of different prefabricated attachment systems for implant-supported overdentures to estimate the wear constancy and applicability in clinical practice. METHODS Four prefabricated attachment systems were tested [Group SG: retentive ball attachment (Straumann, Switzerland) with gold matrix, Group ST: retentive ball attachment (Straumann, Switzerland) with titanium spring matrix, Group IB: UNOR i-Ball with Ecco matrix (UNOR, Switzerland) and Group IMZ: IMZ-TwinPlus ball attachment with gold matrix (DENTSPLY Friadent, Germany)]. Ten samples of each system were subjected to 10,000 insertion-separation cycles. RESULTS Results showed that all types of attachments showed wear, which led to a loss of retention force after an initial increase at the beginning of the wear simulation. Attachments with a plastic retention insert or gold matrices underwent the smallest changes in retention force. The titanium spring system showed the largest changes in retention force and a greater variation between the different cycles and specimen. This behaviour is probably caused by a large fitting tolerance of the titanium spring. CONCLUSIONS Attachment systems which possess a male and female component of different material composition are preferable. They show smaller changes in the retention force. For retention force increase and wear compensation, an attachment system should be adjustable.

Force levels in complex tooth alignment with conventional and self-ligating brackets

INTRODUCTION The force applied to the teeth is a variable of orthodontic treatment that can be controlled. Poor control of the applied force can lead to adverse biologic effects as well as undesirable tooth movements. The selected archwire-bracket combination is a primary determining factor in the force level applied to a tooth during orthodontic treatment. The aim of this research was to use an experimental biomechanical setup to measure forces generated during complex orthodontic tooth movements with various archwire-bracket combinations. METHODS The materials consisted of 3 types of 0.022-in slot orthodontic brackets: (1) conventional brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip [3M Unitek] and Time3 [American Orthodontics, Shegoygan, Wis]), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]); and 4 archwire types: (1) 0.012-in stainless steel (3M Unitek), (2) 0.0155-in coaxial (Advanced Orthodontics [Näpflein, Düsseldorf, Germany]), (3) 0.012-in Orthonol (Rocky Mountain Orthodontics), and (4) 0.012-in Thermalloy (Rocky Mountain Orthodontics). Stainless steel ligatures and elastomeric rings were used. The materials were used in different combinations in a simulated malocclusion that represented a maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis). RESULTS The lowest forces were measured when the brackets were combined with either the coaxial or the Thermalloy archwires; the forces ranged from 3.4 ± 0.2 to 0.7 ± 0.1 N in the x-axis direction, and from 4.5 ± 0.3 to 0.5 ± 0.1 N in the z-axis direction. The highest forces were measured in combination with stainless steel archwires; the forces ranged from 6.3 ± 0.3 to 3.0 ± 0.1 N in the x-axis direction, and from 6.3 ± 0.3 to 1.7 ± 0.1 N in the z-axis direction. CONCLUSIONS We recommend 0.0155-in coaxial and 0.012-in Thermalloy archwires for leveling and alignment. Elastomeric rings, when used with conventional brackets, increased the force applied to the teeth.

The leveling effectiveness of self-ligating and conventional brackets for complex tooth malalignments.

Background and Objective:The transfer of forces and moments between the bracket and archwire is decisive in the multi-band/bracket technique. New developments in bracket design and ligation method aim to optimize the transfer of forces and moments and improve leveling effectiveness. We thus aimed in this study to investigate whether leveling behavior is influenced by different bracket systems, or by the ligation method. The baseline situation for this examination was a complex tooth malalignment.Material and Methods:Using the orthodontic measurement and simulation system (OMSS), we tested the leveling effectiveness of nine self-ligating bracket systems made by various manufacturers (Forestadent-Quick®, in active and passive variants, Dentsply GAC In-Ovation®, adenta TIME®, Ormco Damon® 2 and Damon® 3MX, UP-Dental Opal-M™ and Opal™-2, Strite SPEED™) in the 0.022 inch slot system. A conventional bracket system (Dentaurum discovery®) was used for reference purposes. We also used a multistranded steel archwire (Ormco Tripleflex™, 0.44 mm round) and four nickel-titanium archwires of various diameters (Forestadent® BioStarter® 0.30 mm round, BioStarter® 0.40 mm round, Titanol® Low Force 0.40 × 0.40 mm2 and Titanol® Low Force 0.40 × 0.56 mm2). The leveling task consisted of correcting a complex malalignment (infraocclusion and vestibular displacement, each of 2 mm) of tooth 21. We analyzed the forces and torque movements that arose during the leveling phase.Results:The test of the ten bracket systems revealed no significant difference in terms of their leveling effectiveness. Both selfligating brackets and conventional brackets behaved similarly, and we observed roughly 80% of the infraocclusions to have been corrected. Vestibular displacement was corrected with all the bracket systems by as much as 100% or even more due to a developing torque movement. The influence of wire material and wire diameter became apparent in relation to existing forces durconvening the leveling stage; those factors’ influence was clearly greater than that of the ligation method.Conclusions:This study’s results demonstrate that bracket selection has a negligible influence on leveling effectiveness. Although self-ligating brackets are easier for the orthodontist to manipulate and provide patients with esthetic and wearing comfort advantages, they are not superior to conventional brackets in terms of their biomechanical characteristics.ZusammenfassungHintergrund und Ziel:In der Multiband-Bracket-Technik spielt die Übertragung von Kräften und Drehmomenten zwischen Bracket und Bogen eine entscheidende Rolle. Neuentwicklungen im Bracketdesign und in der Ligierungstechnik waren nicht nur darauf ausgerichtet, die Übertragung von Kräften und Drehmomenten zu optimieren, sondern auch eine bessere Nivellierungseffektivität zu erzielen. Im Rahmen dieser Studie wurde daher untersucht, ob das Nivellierungsverhalten durch verschiedene Bracketsysteme bzw. durch die Ligierungstechnik beeinflusst wird. Dabei stellte eine kombinierte Fehlstellung die Ausgangsposition dar.Material und Methodik:Mit Hilfe des Orthodontischen Messund Simulations-Systems (OMSS) wurden in der vorliegenden Arbeit neun selbstligierende Bracketsysteme im 0.022-Inch-Slotsystem von verschiedenen Herstellern (Forestadent-Quick®, in aktiver und passiver Variante, Dentsply GAC In-Ovation®, adenta TIME®, Ormco Damon® 2 und Damon® 3MX, UP-Dental Opal-M™ und Opal™-2, Strite SPEED™) auf ihre Nivellierungseffektivität untersucht. Ein konventionelles Bracketsystem (Dentaurum discovery®) diente als Referenzmaterial. Außerdem kamen ein geflochtener Stahldrahtbogen (Ormco Tripleflex™, 0,44 mm rund) und vier Nickel-Titan-Drahtbögen unterschiedlicher Querschnitte (Forestadent® BioStarter® 0,30 mm rund, BioStarter® 0,40 mm rund, Titanol® Low Force 0,40 × 0,40 mm2 und Titanol® Low Force 0,40 × 0,56 mm2) zum Einsatz. Die untersuchte Nivellierungsaufgabe bestand in der Korrektur einer kombinierten Fehlstellung (Infraokklusion und vestibuläre Verlagerung von jeweils 2 mm) am Zahn 21. Es wurden die in der Nivellierungsphase auftretenden Kräfte und die Torquebewegung analysiert.Ergebnisse:Die Untersuchung der zehn Bracketsysteme zeigte keine signifikanten Unterschiede im Hinblick auf ihre Nivellierungseffektivität. Sowohl selbstligierende Brackets als auch konventionelle Brackets verhielten sich ähnlich, und es waren Korrekturen der Infraokklusion von ca. 80% festzustellen. Die vestibuläre Verlagerung wurde bei allen Bracketsystemen um bis zu 100% oder sogar darüber hinaus korrigiert, was auf eine auftretende Torquebewegung zurückzuführen war. In Bezug auf die während der Nivellierungsphase auftretenden Kräfte wurde der Einfluss von Drahtmaterial und Drahtquerschnitt deutlich, der den Einfluss der Ligierungsmethode deutlich übertraf.Schlussfolgerungen:Die Ergebnisse der vorliegenden Untersuchung zeigen, dass die Bracketauswahl nur einen geringen Einfluss auf die Nivellierungseffektivität hat. Auch wenn selbstligierende Brackets Vorteile in der Handhabung für den Kieferorthopäden und in Bezug auf Ästhetik oder Tragekomfort für den Patienten bieten mögen, sind sie im Hinblick auf ihre biomechanischen Eigenschaften den konventionellen Brackets nicht überlegen.