Cantilever Length Research Articles

Survival analysis of zirconia implant-supported, fixed complete dentures: A 5-year retrospective cohort study.

Existing data on the mid-term to long-term survival rates of zirconia implant-supported, fixed complete dentures (Zir-IFCDs) are lacking. The purpose of this retrospective clinical study was to assess the prosthetic survival rate in patients treated with Zir-IFCDs. The patient record system at the Dental College of Georgia (DCG), Augusta University was searched to identify all patients treated with Zir-IFCDs from 2015 through 2022 by the DCG graduate prosthodontic, general practice residency, and Advanced Education in General Dentistry (AEGD) programs. Reasons for replacement were grouped as failure of veneering porcelain, framework fracture, implant loss, patient-driven concerns, excessive occlusal wear, and other. A total of 67 arches were found that met the inclusion criteria, 46 maxillary and 21 mandibular. The median follow-up time was 8.5 months (interquartile range, 2.7 to 30.9 months). A total of 9 of the 67 arches were identified as having failed (4 maxillary, 5 mandibular), requiring replacement. Reasons for failure were as follows: 3 framework fractures, 2 implant losses, 2 patient-related concerns, 1 fracture of veneering porcelain, and 1 unknown. The combined survival rate (Kaplan-Meier, log-normal modeling) for Zir-IFCDs was 88.8% at 1 year and 72.5% at 5 years CONCLUSIONS: Based on the findings, the Zir-IFCDs investigated had a survival rate lower than that reported in similar studies, though higher than published results for metal-acrylic resin-IFCDs. The most common source of failure was fracture of the zirconia framework. Thickness of the zirconia framework, interocclusal space, cantilever length, occlusal force, and status of the opposing dentition may have been associated with framework failures and should be investigated further.

Semi-analytical study of defective pile-beam systems under transient excitation: Implications for low-strain testing

This paper establishes a theoretical model of defective pile-beam system. The soil around the pile is modeled as a continuous three-dimensional model. The pile is modeled as a Rayleigh-Love rod model that considers its transversal inertia effect. The defect of the pile is simulated by a pile segment with a different radius from the normal pile segment. The impedance function recursion method, along with RSPT and AIFTM, is utilized to derive the impedance of the pile top. The beam is modeled as a Timoshenko beam and the transient excitation is applied at the connection between the pile and the beam. Analytical solution for the dynamic response of the system in the frequency domain is derived, and the discrete Fourier transform is used to obtain a semi-analytical solution for the time-domain response. The velocity at the connection between the pile and beam and the pile body can be measured to assess defects. The semi-analytical solution presented in this paper was validated through comparison with FEM results. Reflection from necked segment is more pronounced at pile-beam connection than at pile body. Both velocity curves at these two points should be measured when beam cross-section height is large to determine pile integrity. The peak value and arrival time of characteristic waves are influenced by burial depth, necking section parameters, beam cross-section height, cantilever length, and soil parameters. These findings can provide guidance for the application of low strain integrity testing in pile-beam systems.

Investigation of Unwanted Oscillations of Electrically Modulated Magnetoelectric Cantilever Sensors.

Magnetoelectric thin-film cantilevers consisting of strain-coupled magnetostrictive and piezoelectric layers are promising candidates for magnetic field measurements in biomedical applications. In this study, we investigate magnetoelectric cantilevers that are electrically excited and operated in a special mechanical mode with resonance frequencies above 500 kHz. In this particular mode, the cantilever bends in the short axis, forming a distinctive U-shape and exhibiting high-quality factors and a promising limit of detection of 70pT/Hz1/2 at 10 Hz. Despite this U mode, the sensors show a superimposed mechanical oscillation along the long axis. The induced local mechanical strain in the magnetostrictive layer results in magnetic domain activity. Due to this, the mechanical oscillation may cause additional magnetic noise, deteriorating the limit of detection of such sensors. We compare finite element method simulations with measurements of magnetoelectric cantilevers in order to understand the presence of oscillations. From this, we identify strategies for eliminating the external effects that affect sensor operation. Furthermore, we investigate the influence of different design parameters, in particular the cantilever length, material parameters and the type of clamping, on the amplitude of the undesired superimposed oscillations. We propose design guidelines to minimize the unwanted oscillations.

Distal cantilever length comparison in esthetic material for hybrid implant prosthesis: an in vitro study.

Objective: the assessment of distal cantilever length in implant supported prothesis (Hybrid prosthesis) by comparing the load to fracture in two different esthetic framework materials (Zirconia and Polyetheretherketone (PEEK)) with two different cantilevers loading distances (10mm, 15mm). Material and methods: 20 frameworks were fabricated and divided into 4 groups (n=5): according to the material type, Peek, zirconia, and according to the cantilever loading distance (10), or (15) mm and a load-to-fracture test was used until complete fracture of specimens occurs. Results: The effect of material type and cantilever loading distance were statistically significant for the mean load-to-fracture values (P< 0.05). The Zirconia group failed at higher fracture loads (817 N) than the Peek one (651 N). Frameworks with 10 mm cantilever loading distance failed at higher fracture loads than specimens with 15 mm. Conclusion: Peek is a suitable material for hybrid implant prosthesis (with distal cantilever in specific situations, and for zirconia the success chances are higher in these types of prosthesis when the distal cantilever length is kept at its minimal value (10 mm).

The Transverse Vibration Characteristics of Circular Saw Blade on Mobile Cantilever-Type CNC Sawing Machine

A circular saw blade is a commonly used tool in wood processing. The transverse vibration of the saw blade plays an important role in processing quality during cutting and affects its service life as well. In the study, the transverse vibration of the circular saw blade was investigated at the constant rotation by the simulation using ANSYS software when changing the cantilever length of the cantilever woodworking CNC circular saw machine. Meanwhile, the transverse vibration of the circular saw blade without and with load was explored by the eddy current sensors for when the detection point was differently away from the center of the circular saw blade. The time domain, probability density distribution, and power spectrum characteristics of the transverse vibration signal were analyzed, and the simulation values were compared with the actual cutting data. The results revealed that under certain conditions, the maximum transverse vibration value of the circular saw blade was the smallest in the simulation, then the middle in no-load, and the largest in actual cutting. The maximum transverse vibration value of the saw blade was increased with the extension of the cantilevered overhang, but gradually and slightly, indicating the transverse vibration was hardly affected by the change in overhang length of less than 300 mm. The finding provides the reference for the structural optimization design of cantilever CNC circular saw machines and the promotion of its application.

Experimental Investigation of Crack Propagation Mechanism and Load-bearing Characteristics for Anti-slide Pile

Reinforced concrete anti-slide pile is a typical anti-slide installation under horizontal load. Its stress is essentially the cantilever beam working under the combined action of bending moment and shear force. In the process of loading, concrete is accompanied by the generation and expansion of different forms of cracks. In order to reveal the bearing characteristics and crack propagation law of anti-slide pile, the 1:10 scale model of the anti-slide pile in Majiagou landslide treatment project was taken as the object. The mechanical mechanisms of three kinds of the anti-slide piles with different pile lengths were studied. The bending moment and deformation law of three anti-slide piles were obtained. The results show that the pile is easy to crack in the range of 0.5 m above and below the sliding surface. With the increase of cantilever length, the bending moment increases. The development of the maximum crack length and width presents the crack initiation stage, stable stage, and failure mutation stage. Through the monitoring of the length and width of the crack and the judgment of its stage, the working state of the pile can be obtained. The results can provide reference for the optimal design of anti-slide pile in landslide treatment engineering.

A Study Case of Short Dental Implants Loading in the All-On-4® System on Fixed Dental Prostheses: A Finite Element Analysis

The biomechanical research about toothless mandible with four dental implants and a prosthetic system research, which shows the influence of the cantilever length of prosthesis on the weakest structural elements and the load changes in peri-implant bone by changing symmetrically position of the dental implants (in relation to each other), diameters and lengths, and orientation (in relation to chewing surfaces), is not discussed widely in the scientific literature. On the other hand, the use of short implants is more common in practice. Some of these implants are only 8mm in length.The odontologists, implantologists and dental technician can use results received by finite element method (FEM) in the daily clinical practice in order to reduce the potential for mechanical / technological and consequent biological complications already at the planning stage of the treatment, and thus determine best outcomes in the treatment of toothless patients.With a unique interpretation of the results obtained by FEM, the paper discusses the results of implants (8 mm in length with 3.5 mm and 4.5 mm diameter) loading, when the cantilevered dental prostheses are loaded in different positions, as well as implant positions are changed.

Assessment of the Correlation between Implant Diameters and Cantilever Lengths to Anterior-Posterior Spread ratio utilizing Resonance Frequency Analysis (Implant Stability Quotient)

Assessment of the Correlation between Implant Diameters and Cantilever Lengths to Anterior-Posterior Spread ratio utilizing Resonance Frequency Analysis (Implant Stability Quotient)

A Gd‐Film Thermomagnetic Generator in Resonant Self‐Actuation Mode

AbstractThermomagnetic generation is a promising technology for conversion of low‐grade waste heat into electricity. Key requirements for the development of efficient thermomagnetic generators (TMGs) are tailored thermomagnetic materials as well as innovative designs enabling fast heat transfer. Recently, film‐based thermomagnetic generators are developed that operate in the mode of resonant self‐actuation enabling high frequency and stroke of a movable cantilever and, thus, efficient conversion of thermal energy into electrical energy. Here, the performance of a Gadolinium (Gd)‐film‐based TMG that is optimized for resonant self‐actuation near room temperature is reported. The Gd‐film TMG exhibits large oscillation frequencies up to 106 Hz and large strokes up to 2 mm corresponding to 38% of the oscillating cantilever's length. This performance occurs in a sharply bound range of ambient temperatures with an upper limit near the film's ferromagnetic to paramagnetic transition temperature Tc of 20 °C and of heat source temperatures ranging between 40 and 75 °C. The maximum power per footprint is 23.8 µWcm−2, at which the Gd film undergoes a temperature change of only 0.9 °C at ≈10 °C above Tc.

Retrospective Cohort Evaluation of Full-Arch Zirconia Implant-Supported Fixed Prostheses.

Objective: To determine the median event-free survival and relative complication rates of monolithic and minimally layered full-arch zirconia prostheses, as well as to identify risk factors for prosthesis complications. Materials and Methods: In this retrospective cohort study, a total of 129 subjects (173 prostheses) were included in the chart review and 56 subjects (75 prostheses) participated in a clinical follow-up visit. All subjects had either single- or dual-arch monolithic or minimally layered zirconia implant-supported prostheses. Data related to patient, implant, and prosthesis factors were extracted from charts. The subgroup that presented for a clinical visit were asked to complete a satisfaction questionnaire. For this subgroup, the following clinical measures were assessed: routine intraoral examination, number of occluding units, cantilever length on each side of the prosthesis (right and left), prosthesis height, occlusal scheme, and oral hygiene methods. Periapical radiographs were obtained when the last radiographs of the patient were taken more than 12 months prior. Results: The follow-up period ranged from 12 months to 7.1 years (mean: 1.9 years). Observed complications included implant loss, peri-implantitis, mucositis, purulence, sinus tract formation, oroantral communication, implant fracture, titanium base debonding, ceramic chipping, prosthetic screw fracture or loosening, damage to opposing teeth, and clicking sounds. There was an insufficient number of complications to evaluate the effect of covariates on the risk of specific complications, such as titanium base debonding (eight events), ceramic chipping (nine events), and peri-implantitis (eight events). The unadjusted event-free median survival time was 5.8 years. The proportion of all prostheses with at least one complication was 30%. There were no observed prosthesis losses during the follow-up period. Conclusion: Monolithic and minimally layered zirconia full-arch implant-supported prostheses demonstrate an acceptable median event-free survival time. Event-free survival times were increased and the number of complications was reduced in prostheses with five to eight implants and conventional (as opposed to zygomatic) implants. There was a reduced hazard of complications with a regular recall regimen. Patient satisfaction with these prostheses was high.

Lateral buckling capacity of steel H-piles supporting integral abutment bridges (IABs)

Integral abutment bridges (IABs) have been gaining wide popularity in the United States and neighboring countries due to the rapid increase in maintenance costs associated with conventional bridges. The elimination of expansion joints in IABs allows the thermally induced lateral demand in the superstructure to be transferred to the supporting piles. This paper aims to study the behavior of steel H-piles supporting IABs through a detailed nonlinear finite element analysis that was calibrated and validated against available experimental data. A total of 30 models were established to examine the effect of various parameters (pile size, pile orientation, pile material yield strength, pile equivalent cantilever length, and axial compressive load) on piles supporting jointless bridges subjected to a combined axial load and lateral cyclic displacement amplitude. Local buckling was the dominant failure mode for all the specimens. Furthermore, this paper reiterates the various parameters and assesses their influence through a statistical regression analysis to develop an empirical formula for calculating the lateral buckling capacity. The rationality of the developed formula was examined and tested with existing experimental data, which testified the reliability to be used for future design considerations.

Study on Fracture Behavior of Directly Covered Thick Hard Roof Based on Bearing Capacity of Supports

Mine pressure at the working face is severe due to it being directly covered by a thick hard roof. To further investigate the technology of controlling the mine pressure of a thick hard roof, the upper working face of 13,121 in Gubei mine of Huainan mining area was used as the engineering background, and similar simulation experiments, mechanical analysis, numerical simulation, and engineering applications were used to obtain the structure of a pre-cracked cut roof cut falling body, as well as establishing the mechanical model of hydraulic brace support resistance and direct covering. The results of the numerical simulation combined with the 20 m step pre-cracked top cutting showed that the cantilever length of the roof plate in the mining area was shortened by 25.61%, the stress concentration was reduced by 31.74%, and the stress level of the hydraulic brace was reduced by 26.59–28.38%, destroying the integrity of the thick hard rock body. According to the field monitoring data analysis, the working face’s initial pressure step and periodic pressure step were reduced, and the average dynamic load coefficients of the initial pressure and periodic pressure were 1.43 and 1.33, respectively, with a small dispersion of the dynamic load coefficient of the bracket. The pressure at the working face is regulated, and the chosen support equipment, in conjunction with the roof cutting scheme, can meet the thick hard roof’s support needs.

Strains in the implant collars supporting a cantilevered cross-arch bar prosthesis. An in vitro study.

To examine the strains in the collar area of implants supporting a cantilevered cross-arch bar prosthesis during vertical load application. A milled cross-arch metal framework supported by four implants in a trapezoidal design was supported in polymethylmethacrylate. T-strain gage rosettes were attached to the crestal areas of the implants with two grids, one recording circumference strain of the crestal area of the implant and the second recording vertical strain, torquing strains of the implant. The framework was subject to vertical loading from an MTS 810 mechanical system. Loading sites were directly on anterior and posterior implants, and on a cantilever at 7.5, 15, 22.5, and 30mm (0.5, 1.0, 1.5, and 2.0 of the anterior-posterior spread) distal from the posterior implant on the right side. The anterior-posterior (A-P) spread from anterior to posterior implants was 15mm. Sites were loaded individually with 50 and 100N. The data from the rosettes were transferred to a desktop computer and processed using StrainSmart 5000 software. Means and standard deviations were calculated for the 10 trials at each of the loading sites. Two-way ANOVAs were done separately for each dependent variable, the vertical grid, and the circumferential grid. The independent variables were the load magnitude and the load site. Tukey's test was used to compare groups post hoc. When directly loading the implants, loading the anterior implant resulted initially in compression followed by increasing tensile strain with 100N loads. Loading the implant adjacent to cantilever (the posterior implant) resulted in greater strain at the collar than that observed with anterior implant with minimal bending strains. When loading the cantilever, anterior implant showed increasing bending strain at greater cantilever length, whereas the circumferential strains were greater for the supporting implant adjacent to the cantilever, particularly at 100N loads, p≤0.001. Limiting cantilever lengths to A-P spread ratios of 0.5 are preferred. Ratios greater than 1.0 should be avoided as flexing of the collar may occur. The dimensions of the implant, particularly wall thickness, adjacent to the cantilever should be carefully considered when planning the cantilevered implant-supported prosthesis.

Effect of Poly‐Crystallinity on the Magnetoelectric Behavior of TiN/AlN/Ni MEMS Cantilevers Investigated by Finite Element Methods

Herein, magnetoelectric microelectromechanical system (MEMS) cantilevers are investigated on basis of a TiN/AlN/Ni laminate derived from experimental sensors using finite‐element simulations. With the anisotropic ΔE effect as an implication of the magnetocrystalline anisotropy, the lateral sensitivity of the sensor is studied for different nickel layer thicknesses and boundary conditions. It is found that above 60% of the cantilever length, the nickel is effectively not contributing to the sensor sensitivity anymore which is supported by the investigation of sensors with partial nickel coverage. The boundary condition of the magnetostrictive layer is found to affect the sensitivity of thick layers while it is negligible for thinning layers. Further investigations on basis of polycrystalline untextured nickel with slightly preferred orientations reveal a stronger effect on thin layers than on thicker ones. It is found to arise from relatively large crystals in the high‐sensitivity region near the clamping of the sensor. For thicker polycrystalline layers, the ΔE effect reproduces a characteristic based mainly on the (110) and (111) orientations while the (100) orientation appears to be underrepresented.

Piezoelectric energy harvesting from extremely low-frequency vibrations via gravity induced self-excited resonance

In this paper, we originally present a gravity induced self-excited vibration generator based on a cantilever piezoelectric resonator. The configuration is composed of a sliding rod, a sleeve, a transduction unit. To estimate output voltage and investigate dynamic responses of the generator, an equivalent model based on mechanical structure was established and numerically solved. The effects of the cantilever length, tip mass and linear coupling factor on the open circuit voltage were discussed. In addition, we also conducted series of experiments to validate the theoretical responses. In a 10s cycle (namely 0.1Hz excitation frequency) scenario, the transduction unit responds with structural resonant frequency of 8.621Hz. The results of the experiments show that the open circuit voltage of the generator increases with increment of the cantilever beam length and the tip mass, which agrees well with simulation estimations. We also conducted impedance matching experiments to examine power response in the load spectrum, of which the results indicate that the prototype peak power reaches maximum 1.897 mW. We also discussed the change of gravity potential energy of the prototype and compared it with electric energy. This work provides a novel approach for piezoelectric energy harvesting from extremely low frequency excitations.

Controllable Three-Dimensional DNA Nanomachine-Mediated Electrochemical Biosensing Platform for Rapid and Ultrasensitive Detection of MicroRNA.

In this work, a high-efficiency controllable three-dimensional (3D) DNA nanomachine (CDNM) was reasonably developed by regulating the diameter of the core and the length of the DNAzyme cantilever, which acquired greater amplification efficiency and speedier walking rate than traditional 3D DNA nanomachines with gold nanoparticles as the cores and DNAzymes as the walking arms. Significantly, once the target miRNA-21 existed, a large number of silent DNAzymes on the CDNM could be activated by enzyme-free-target-recycling amplification (EFTRA) to achieve fast cleavage and walking on the biosensor surface under the interaction of Mg2+. Impressively, when the diameter of the core was 40 nm and the length of the DNAzyme cantilever was 5 nm (15 bp), the CDNM could complete the reaction process in 60 min that was at least twice shorter than those of conventional DNA nanomachines. Moreover, the designed electrochemical biosensor successfully detected target miRNA-21 at an ultrasensitive level with a wide response range (100 aM to 1 nM) and a low detection limit (33.1 aM). Therefore, the developed CDNM provides a new idea for exploring functional DNA nanomachines in the field of biosensing for applications.

Effect of implant diameter and cantilever length on the marginal bone height changes and stability of implants supporting screw retained prostheses: A randomized double blinded control trial.

This randomized controlled trial aimed to evaluate the effect of implants' two different diameters and cantilever lengths on the marginal bone loss and stability of mplants supporting maxillary prostheses. Ninety-six implants were placed in sixteen completely edentulous maxillary ridges. Patients were randomly divided into two groups: Group A, implants were placed with a cantilever to anterior-posterior AP spread length (CL:AP) at a ratio of 1:3; Group B, implants were placed with a CL:AP at a ratio of 1:2. Patients were further divided into four sub-groups: Groups A1, A2, B1, and B2. Groups A1 and B1 received small diameter implants while Groups A2 and B2 received standard diameter implants. Bone height and stability measurements around each implant were performed at 0, 4, 8 and 24 months after definitive prostheses delivery. Statistical analysis of the mean implant stability and height values revealed an insignificant difference between Group A1 and Group A2 at all the different time intervals while significantly higher values in Group B1 in comparison with Group B2. Results also showed significantly higher values in Group A1 in comparison with Group B1 and an insignificant difference between Group A2 and Group B2 at all the different time intervals. It can be concluded that the use of small diameter implants placed with a CL:AP at a ratio of 1:3 provided predictable results and that the 1:2 CL:AP significantly induced more critical bone loss in the small diameter implants group, which can significantly reduce long term success and survival of implants.

Comparative photoelastic stress analysis between all-on-four implant-supported cobalt-chromium framework and carbon fiber reinforced framework with varying cantilever lengths - An in vitro study

CONTEXT: In implant prosthodontics, metal frameworks are used to rigidly spilt the implants together to provide rigidity and stiffness to the prosthesis. However, due to the limitations associated with the metal framework fabrication, the recent advances have made it possible to fabricate metal-free implant-supported prostheses using fiber-reinforced composite frameworks.AIM: This study aimed to evaluate and compare photoelastic stresses between all-on-four implant-supported cobalt-chromium (Co-Cr) framework and the carbon fiber-reinforced composite (CFRC) framework at varying cantilever lengths.MATERIALS AND METHODS: Two photoelastic models of an edentulous mandible were fabricated according to the all-on-four concept. Following this, frameworks with a bilateral cantilever extension of 20 mm, one with CFRC and the other with Co-Cr, were fabricated and were subjected to a progressive load of 120–180 N with an interval of 20 N. The principal stresses (σ) were calculated using the mean maximum fringe order.STATISTICAL ANALYSIS: The quantitative analysis was performed using the Kruskal–Wallis test and Mann–Whitney U-test, P ≤ 0.05.RESULTS: The CFRC framework showed mean principal stress values significantly lower than the Co-Cr framework under all loading conditions; however, deformation of the framework was observed at the cantilever lengths of 15 mm and 20 mm.CONCLUSION: The study and its findings have indicated that the CFRC framework appears suitable for the fabrication of a framework for an “All-on-four” prosthesis. Within the confines of this study, the use of 10 mm as an arbitrary cantilever length recommendation for the CFRC framework and 15 mm for the Co-Cr framework seems reasonable.

A Correlation Study between different Implant Diameters and Cantilever Lengths on the Marginal Bone Loss of Implant Supported Maxillary Prostheses: A Randomized Controlled Trial

A Correlation Study between different Implant Diameters and Cantilever Lengths on the Marginal Bone Loss of Implant Supported Maxillary Prostheses: A Randomized Controlled Trial

Flexural design of restraining panels in buckling-restrained steel plate shear walls considering high-order buckling modes

Buckling-restrained steel plate shear wall (BRSPSW) is one kind of excellent energy dissipating member. The inner steel plate in BRSPSW usually works with high-order buckling modes to resist lateral force under the buckling restrained effect of outer restraining panels. However, current design of the restraining panels is commonly based on simplified uniform-loaded plates without considering the effect of the high-order buckling modes, which may result in unsafe designs. In this paper, the high-order buckling modes in BRSPSW and their influence on the flexural design of the restraining panels were studied. Finite element (FE) models that can accurately simulate the out-of-plane interaction behavior of BRSPSW were developed and verified by existing test results. The numerical results show that the high-order buckling of the steel plate leads to a series of inclined strip-shaped stress regions on restraining panels. When the parameters of BRSPSW are varied in common range, the positive and negative bending moments of the restraining panel under the strip-shaped force are 9.6 and 2.8 times those under the uniform force, respectively. The differences between the bending moment of the restraining panels under strip-shaped force and that under uniform force become larger as the spacings of the strip-shaped stress regions increase. Furthermore, the spacings of the strip-shaped stress regions increase with the decrease of the height-to-thickness ratio of the steel plate and the increase of the gap between the steel plate and the restraining panel. Two fitting formulas of the positive and negative moment amplification factors considering the effect of the high-order buckling modes are proposed to design the restraining panels safely. Additionally, a simplified model and bending moment equations of the restraining panels in BRSPSW are suggested. To avoid the excessive negative bending moments occurring at side supports of the restraining panel, the ratio of cantilever length to middle span is suggested to be not more than 0.4.