Mechanical and numerical investigations of biodegradable magnesium alloy screws for fracture treatment.

Small fracture treatment includes the use of so-called "Herbert screws". In the past years, novel resorbable materials were introduced as an alternative to the classical titanium implants. The purpose of this study was to evaluate the influence of ongoing resorption/corrosion processes on the mechanical stability screws made from the magnesium alloy MgYREZr®.

Variation of the modulus of elasticity of aligner foil sheet materials due to thermoforming.

Objective: Investigate and compare the mechanical properties of different aligner materials before and after deep drawing and determine differences in the mechanical properties after thermoforming.

Materials And Methods: Four aligner film sheets from three manufacturers (Duran Plus® [Scheu Dental, Iserlohn, Germany]; Zendura® [ClearCorrect, Bay Materials LLC, Fremont, CA, USA]; Essix ACE® and Essix® PLUS™ [Dentsply Sirona Deutschland, Bensheim, Germany]) were tested in 3‑point bending with support distances of 8, 16, and 24 mm. Dimension of the specimens was 10 × 50 mm.

Numerical and biomechanical analysis of orthodontic treatment of recovered periodontally compromised patients.

Objective: Generate a finite element (FE) model to simulate space closure and retraction mechanics for anterior maxillary teeth in periodontally compromised dentition, and compare the biomechanical effect of initial force systems with varying magnitude.

Materials And Methods: The geometry of an idealized finite element model (FEM) of a maxilla was adapted such that the teeth showed reduced periodontal support together with extruded and flared incisors. In a first step, leveling and alignment of the front teeth were simulated.

Impact of the endocannabinoid system on murine cranial and alveolar bone phenotype.

Purpose: The endocannabionoid signaling system has been demonstrated to be present in the skeleton, with involvement in the regulation of skeletal homeostasis. However, investigations substantiating these findings in cranial and alveolar bones are missing to date. The aim of our study was to investigate a potential impact of the endocannabinoid system on cranial and alveolar bone structures and phenotypes.

Biomechanical analysis of initial incisor crowding alignment in the periodontally reduced mandible using the finite element method.

Aims: To reduce remaining plaque niches due to dental malocclusion after periodontal treatment and to avoid reinflammation of periodontitis, severe anterior crowding can be treated orthodontically. The treatment indication is motivated by aesthetic and functional needs. In this study the biomechanical behaviour of crowded lower front teeth in reduced periodontium is analysed.

Comparative study on serum-induced arthritis in the temporomandibular and limb joint of mice.

Introduction: The subject of the present study was a systematic comparative analysis of the rheumatoid arthritis (RA)-induced pathomechanisms in the temporomandibular joint with those of the limb joints using the serum-induced arthritis K/BxN model.

Methods: In 18 BALB/c mice the induction of RA was performed according to the Kouskoff method. Another healthy cohort served as controls (n = 12).

Numerical investigations of bone remodelling around the mouse mandibular molar primordia.

The formation of the alveolar bone, which houses the dental primordia, and later the roots of tooth, may serve as a model to approach general questions of alveolar bone formation. In this respect, this study aimed to investigate the potential interactions between the alveolar bone formation and tooth eruption by using finite element (FE) methods, and to figure out whether the expanding tooth systems induce shear stresses that lead to alveolar bone formation. 3D geometric surface models were generated from the 3D histological data of the heads of mice (C57 Bl/6J) ranging from stages embryonic (E) to postnatal (P) stages E15 to P20 using the reconstruction software 3-Matic.

The influence of enamel sandblasting on the shear bond strength and fractography of the bracket-adhesive-enamel complex tested in vitro by the DIN 13990:2017-04 standard.

Objectives: This study was conducted in order to investigate whether enamel sandblasting as an adjunct or substitute to the acid-etch technique has an effect on the shear bond strength (SBS) and fractography of the bracket-adhesive-enamel complex using the DIN 13990:2017-04 standard.

Materials And Methods: Upper central incisor brackets (discovery®, Dentaurum, Germany) were bonded using Transbond XT™ (3M Unitek, Germany) on bovine incisors prepared by four different methods (15 samples each): sandblasting with 27 μm AlO at 1.2 bar (s), acid etching with 37.

Effectiveness of photopolymerization in composite resins using a novel 445-nm diode laser in comparison to LED and halogen bulb technology.

Challenges especially in the minimal invasive restorative treatment of teeth require further developments of composite polymerization techniques. These include, among others, the securing of a complete polymerization with moderate thermal stress for the pulp. The aim of this study is to compare current light curing sources with a blue diode laser regarding curing depth and heat generation during the polymerization process.

Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study.

Background/objective: The aim of this study was to evaluate the efficacy of tooth alignment with conventional and self-ligating labial and lingual orthodontic bracket systems.

Materials/methods: We tested labial brackets (0.022″ slot size) and lingual brackets (0.

Time-dependent behavior of porcine periodontal ligament: A combined experimental, numeric in-vitro study.

Introduction: The aim of this study was to analyze the time-dependent in-vitro behavior of the periodontal ligament (PDL) by determining the material parameters using specimens of porcine jawbone. Time-dependent material parameters to be determined were expected to complement the results from earlier biomechanical studies.

Methods: Five mandibular deciduous porcine premolars were analyzed in a combined experimental-numeric study.

Influence of tooth dimension on the initial mobility based on plaster casts and X-ray images : A numerical study.

Aims: The goal was to determine the influence of different geometric parameters of the tooth on the initial tooth mobility and the position of the center of resistance employing numerical models based on scaled X-ray images and plaster casts.

Methods: The dimensions of tooth 21 were measured in 21 patients, using radiographs and dental casts. Length and mesiodistal width of the tooth were obtained from the X-ray image and the orovestibular diameter from the plaster cast.

Mechanical properties of different esthetic and conventional orthodontic wires in bending tests : An in vitro study.

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.

Imaging of Dental Hard Tissue Surfaces Prepared by an Ultrashort Pulsed Laser System (USPL).

The aim of this study was to compare surface structures of laser-irradiated dental hard tissues using confocal (CFM), atomic force (AFM), and scanning electron microscopy (SEM). The general potential of the AFM in analyzing laser-irradiated surfaces was determined in this context. Specimens of human enamel and dentin were irradiated using an 8.

Friction behavior of self-ligating and conventional brackets with different ligature systems.

Objectives: Self-ligating brackets are widely believed to offer better clinical efficiency and, in particular, less friction. Thus, the goal of this in vitro investigation was to assess the friction behavior of different bracket/archwire/ligature combinations during simulated canine retraction. An important aspect of this work was to determine whether conventional bracket systems behave differently in passive or active self-ligating brackets used with a Slide™ ligature, an elastic ligature, or a steel ligature.

Friction behavior of ceramic injection-molded (CIM) brackets.

Objectives: Bracket material, bracket design, archwire material, and ligature type are critical modifiers of friction behavior during archwire-guided movement of teeth. We designed this in vitro study to compare the friction losses of ceramic injection-molded (CIM) versus pressed-ceramic (PC) and metal injection-molded (MIM) brackets-used with different ligatures and archwires-during archwire-guided retraction of a canine.

Methods: Nine bracket systems were compared, including five CIM (Clarity™ and Clarity™ ADVANCED, both by 3M Unitek; discovery(®) pearl by Dentaurum; Glam by Forestadent; InVu by TP Orthodontics), two PC (Inspire Ice by Ormco; Mystique by DENTSPLY GAC), and two MIM (discovery(®) and discovery(®) smart, both by Dentaurum) systems.

Experimental investigation of the fracture torque of orthodontic anchorage screws.

Objectives: In contrast to dental implants that remain in the bone, orthodontic anchorage screws serve as temporary anchorage for orthodontic tooth movement and are removed after completion of treatment. The aim of the present study was to evaluate the stability of various commercially available orthodontic anchorage screws against torsion.

Materials And Methods: The torsional deflection of ten different orthodontic anchorage screws from different manufacturers [Ortho Easy Pin (Forestadent), Benefit, quattro (both PSM Medical Solutions), Vector TAS (Ormco), AbsoAnchor(®) (DENTOS Inc.

Nickel ion concentrations in the saliva of patients treated with self-ligating fixed appliances: a prospective cohort study.

Objective: Orthodontic appliances are considered to be highly biocompatible although adverse effects attributed to the release of nickel ions (Ni(2+)) have been documented. Self-ligating brackets have grown in popularity for economic reasons and supposed friction reduction. The aim of the present prospective cohort study was therefore to determine salivary Ni(2+) concentrations in patients undergoing orthodontic treatment with self-ligating fixed appliances.

Symmetric and asymmetric expansion of molars using a Burstone-type transpalatal arch. Biomechanical and clinical analysis.

Objectives: A transpalatal arch (TPA) directly connecting the maxillary first molars can be used in passive (for stabilization) and active (for molar or segment movement) modes. Activation may be symmetric or asymmetric. This study was performed to analyze the effectiveness of TPAs for transverse expansion treatment by measuring both the force systems they deliver and the clinical tooth movements thus achieved.

Effect of archwire cross-section changes on force levels during complex tooth alignment with conventional and self-ligating brackets.

Introduction: Our objective was to investigate the effect of archwire cross-section increases on the levels of force applied to teeth during complex malalignment correction with various archwire-bracket combinations using an experimental biomechanical setup.

Methods: The study comprised 3 types of orthodontic brackets: (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip, a passive self-ligating bracket [3M Unitek]; and Time3 [Rocky Mountain Orthodontics, Denver, Colo] and SPEED [Strite Industries, Cambridge, Ontario, Canada], both active self-ligating brackets), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]). All brackets had a nominal 0.

A comparative experimental investigation of torque capabilities induced by conventional and active, passive self-ligating brackets.

Introduction: A proper selected bracket-archwire combination displays a determining factor in the efficacy of torque applied to a tooth at the final stages of an orthodontic treatment. The objective of the current study was to assess the torque capabilities of various bracket systems combined with diverse archwire materials and cross-sections.

Methods: The study comprised of four different 0.

Different bracket-archwire combinations for simulated correction of two-dimensional tooth malalignment: Leveling outcomes and initial force systems.

Objectives: Self-ligating brackets are widely believed to be more effective in clinical use and to involve less friction and force. Thus, the goal of this in vitro investigation was to experimentally assess the effectiveness of different bracket-archwire combinations and the force levels exerted in two-dimensional direction during correction of tooth malalignment. An important aspect of this objective was to determine whether the behaviors of conventional bracket systems with an elastic or steel ligature differ from that of self-ligating brackets.

Long- and short-term effects of headgear traction with and without the maxillary second molars.

Introduction: A quantitative assessment of maxillary first molar distalization with and without the maxillary second molar (M2) was carried out.

Methods: Fifty-six cervical headgear patients undergoing fixed appliance orthodontic treatment were divided into 2 groups: before (G - M2) and after (G + M2) eruption of the maxillary second molars (ages, 11.87 ± 1.

Friction behavior and other material properties of nickel-titanium and titanium-molybdenum archwires following electrochemical surface refinement.

Objectives: The aim of this work was to investigate whether electrochemical surface treatment of nickel-titanium (NiTi) and titanium-molybdenum (TiMo) archwires (OptoTherm and BetaTitan; Ortho-Dent Specials, Kisdorf, Germany) reduces friction inside the bracket-archwire complex. We also evaluated further material properties and compared these to untreated wires.

Materials And Methods: The material properties of the surface-treated wires (Optotherm/LoFrix and BetaTitan/LoFrix) were compared to untreated wires made by the same manufacturer (see above) and by another manufacturer (Neo Sentalloy; GAC, Bohemia, NY, USA).

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.