A comparative assessment of the forces and moments generated with various maxillary incisor intrusion biomechanics.

The aim of this study was to comparatively evaluate the intrusive forces and buccolingual torquing moments generated during anterior maxillary intrusion using different maxillary incisor intrusion mechanics. Five wire specimens were used for each of the following intrusive arches: blue Elgiloy utility arch 0.016 x 0.

Development and design of a novel loading device for the investigation of bone adaptation around immediately loaded dental implants using the reindeer antler as implant bed.

The assessment of the behavior of immediately loaded dental implants using biomechanical methods is of particular importance. The primary goal of this investigation is to optimize the function of the implants to serve for immediate loading. Animal experiments on reindeer antlers as a novel animal model will serve for investigation of the bone remodeling processes in the implant bed.

Forces and moments generated with various incisor intrusion systems on maxillary and mandibular anterior teeth.

Objective: To evaluate the comparative intrusive forces and torquing moments in the sagittal plane generated during anterior intrusion using different incisor intrusion mechanics in the maxillary and mandibular anterior teeth.

Materials And Methods: Five wire specimens were used for each of the following intrusive arches: non-heat-treated, 0.016 x 0.

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.

Proliferation and differentiation of periodontal ligament cells following short-term tooth movement in the rat using different regimens of loading.

Previous studies have indicated that periodontal ligament (PDL) cells demonstrate osteogenic potential and osteoblastic differentiation via the extracellular signal-regulated kinase (ERK) pathway under mechanical stress in vitro and in vivo. This study aimed to further analyse this regulatory process experimentally in the rat. The right upper first molars of 25 twelve-week-old male Wistar anaesthetized rats were loaded with forces in order to be moved mesially.

Numerical investigation of the mechanical loading of supporting soft tissue for partial dentures.

The aim of this research was to study the impact of loading on partial dentures within the supporting soft tissue with respect to different attachment techniques. A finite element model was developed to calculate the stress and strain distribution in this tissue. The model consisted of the left half of a mandible with three remaining teeth that had suffered an atrophy in the anterior region, and a partial denture over the toothless area that was connected at the left mandibular canine using an attachment system.

Comparative assessment of forces generated during simulated alignment with self-ligating and conventional brackets.

The objectives of this study were to comparatively assess the magnitude and direction of forces and moments generated from different bracket systems, during the initial levelling and alignment stage of orthodontic treatment. Three types of brackets were used: Orthos2 (Ormco), Damon2 (Ormco), and In-Ovation R (GAC). The brackets were bonded on resin replicas models of a patient's crowded mandibular arch, and a 0.

[Biomechanical analysis of orthodontic brackets with different closing mechanisms].

The aim of the present study was to investigate the biomechanical characteristics of orthodontic bracket systems made of metal, ceramics or plastics. Six different types of brackets were studied, including the Hanson Speed- and Damon 2-Brackets, both of which are equipped with specialised closing mechanisms. In addition, two conventional metal brackets (Ultratrimm), Discovery, the ceramics bracket Fascination 2 and the polycarbonate bracket Brillant were investigated.

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.

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.

In-vitro evaluation of the corrosion behavior of orthodontic brackets.

Objective: The number of bracket systems for orthodontic therapy increases significantly. One major concern of newly developed orthodontic devices is aspects of corrosion and biocompatibility.

Material And Methods: In this study, nine bracket systems made of different material and from various design principles were tested with respect to their corrosion behavior.

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.

Numerical and clinical study of the biomechanical behaviour of teeth under orthodontic loading using a headgear appliance.

It was the purpose of this study to analyse the biomechanical behaviour of posterior teeth under headgear traction with neighbouring teeth in different eruption stages. For doing so a finite element (FE) model of the right part of a human maxilla was developed, based on an almost anatomically correct commercial surface data set of a human maxilla. The FE model included the first molar (M1) with surrounding tooth supporting structures as well as the second (M2) and third molars (M3) in different eruption stages.

Moments generated during simulated rotational correction with self-ligating and conventional brackets.

Objective: To assess comparatively the magnitude of moments generated during rotational correction from different bracket systems during the late leveling and alignment stage of orthodontic treatment.

Materials And Methods: The three types of brackets assessed were Orthos2 (ORMCO, Glendora, CA), Damon2 (ORMCO), and In Ovation-R (GAC, Bohemia, NY). The brackets were bonded on replicas made of resin from models constructed from an aligned patient's mandibular arch, and a 0.

Finite element representation of bone substitute remodelling in the jaw bone.

The finite element (FE) method was originally developed on a physical basis for the computation of structure-mechanical problems. Meanwhile, it has been widely applied to medical issues. This study sought a suitable method to build a FE model for remodelling processes in osseous defects supplemented with bone substitute material.

Torque expression of self-ligating brackets compared with conventional metallic, ceramic, and plastic brackets.

The purpose of this research was to investigate the torque capacity of active and passive self-ligating brackets compared with metallic, ceramic, and polycarbonate edgewise brackets. Six types of orthodontic brackets were included in the study: the self-ligating Speed and Damon2, the stainless steel (SS), Ultratrimm and Discovery, the ceramic bracket, Fascination 2, and the polycarbonate bracket, Brillant. All brackets had a 0.

Time-related PDL: viscoelastic response during initial orthodontic tooth movement of a tooth with functioning interproximal contact-a mathematical model.

Most anteroposterior orthodontic movements of posterior teeth have to overcome the "resistance" of adjacent teeth with functioning interproximal contacts. The aim of this study was to develop a mathematical model describing initial posterior tooth movement associated with functioning interproximal contacts in relation to the viscoelastic mechanical behavior of the human periodontal ligament (PDL). A linear viscoelastic 2D mathematical model was modified to depict tipping movement around the center of rotation (C(rot)) of a premolar where tipping is restrained by adjacent teeth.

Forces exerted by conventional and self-ligating brackets during simulated first- and second-order corrections.

Introduction: Our aim in this study was to comparatively assess the forces generated from conventional and self-ligating bracket systems during the late leveling and alignment stage, specifically for first- and second-order movement.

Methods: Three types of brackets were selected: Orthos2 (Ormco, Glendora, Calif), Damon2 (Ormco), and In Ovation-R (GAC, Bohemia, NY). The brackets were bonded on resin replicas constructed from a model of an aligned mandibular arch, and a 0.

Fatigue failure of as-received and retrieved NiTi orthodontic archwires.

Aim: To investigate the fracture resistance of as-received and retrieved NiTi archwires.

Materials And Methods: NiTi archwires (German Orthodontics, CA, USA) of various cross-sections were retrieved from orthodontic patients and brand-, type- and size-matched wires were included as controls. Specimens prepared from the selected wires were subjected to bending deformation at a loading frequency of 2 Hz and cyclic loading was applied either until fatigue failure or with a maximum number of loading cycles of 2 x 10(6).

Changes in the stiffness of the ligating mechanism in retrieved active self-ligating brackets.

Introduction: The purpose of this study was to investigate the effect of intraoral aging on the force applied during engagement of a wire into the slot of active self-ligating brackets.

Methods: Two types of brackets were used: Speed (Speed System Orthodontics, Cambridge, Ontario, Canada) and In Ovation-R (GAC, Bohemia, NY). Ten as-received and 10 retrieved maxillary incisor brackets collected after full treatment for at least 15 months (range, 15-19 months) were included in each bracket group.

Regulatory effects of biophysical strain on rat TMJ discs.

Recent studies have revealed that dynamic biomechanical forces can exert antiinflammatory and antiproteolytic effects on fibrocartitage. Whether the effects of mechanical strain also involve stimulation of the insulin-like growth factor (IGF) system and, therefore, of growth and repair of fibrocartilage has yet to be determined. The objective of this in vitro study was to determine if continuous biophysical strain regulates the gene expression of IGF1, IGF2, IGF1 receptor (IGF1R), insulin receptor substrate (IRS1), and IGF-binding proteins (IGFBP) 3 and 5 in cells from the fibrocartilaginous disc of the temporomandibular joint (TMJ).

Why do nickel-titanium archwires fracture intraorally? Fractographic analysis and failure mechanism of in-vivo fractured wires.

Introduction: The aim of this study was to characterize intraorally fractured nickel-titanium (Ni-Ti) archwires, determine the type of fracture, assess changes in the alloy's hardness and structure, and propose a mechanism of failure.

Methods: Eleven Ni-Ti SE 200 and 19 copper-Ni-Ti (both, Ormco, Glendora, Calif) intraorally fractured archwires were collected. The location of fracture (anterior or posterior), wire type, cross section, and period of service before fracture were recorded.

Investigation of the wear of prefabricated attachments--an in vitro study of retention forces and fitting tolerances.

Objective: To quantify wear processes by measuring the retention force changes and the fitting tolerance at different prefabricated attachment systems to estimate the wear constancy and applicability in clinical practice.

Method And Materials: Seven prefabricated attachment systems (Dalbo-Classic, Dalbo-PLUS, Dalbo-Z, Mini-Gerber-PLUS, Stufenexzenter, SpharoLock, and Degussa-Kugelankersystem) with different construction and alloy composition were tested. Twenty samples of each system were subjected to 10,000 insertion-separation cycles in a wear simulator with a periodontium-simulating specimen holder.

Computer-aided analysis of the biomechanics of tooth movements.

Orthodontic biomechanics started in the early 1960s with the work of Burstone and later Nikolai. Experimental and theoretical studies using finite element methods (FEM) focused on the determination of the position of the center of resistance of single and multi-rooted teeth. Due to the complex structure of the system tooth/periodontal ligament/alveolar bone and because of the limited power of computers, the first numerical models were quite simple.

Biomechanical finite-element investigation of the position of the centre of resistance of the upper incisors.

The position of the centre of resistance (CR) is an essential parameter regarding the planning of orthodontic tooth movements. In the present investigation, the combined CR of the upper four incisors was determined numerically using the finite-element (FE) method. Based on a commercially available three-dimensional data set of a maxilla, including all 16 teeth, as well as known and earlier determined material parameters, FE models of the upper incisors and their surrounding tooth-supporting structures were generated.