Wear Factor Research Articles

Parametric optimization of the machining performance of Al-SiCp composite using combination of response surface methodology and desirability function

In this study, machining parameters such as speed, feed, and depth of cut were optimized for maximum material removal rate (MMR) of Al-SiCp composite turned with a tungsten carbide tool using response surface methodology based central composite design while keeping tool wear and surface roughness within specified limits. The influence of turning factors on flank wear and surface roughness height was investigated using regression models. ANOVA analysis is used to assess the appropriateness of the projected models and the significant factors for response optimization using the desirability method. The percentage contribution of the significant machining parameters and their interactions for optimization of the response is determined using ANOVA technique. Cutting speed is found to be the most significant factor for flank wear, average roughness height Ra and maximum roughness height Rt with contribution of 65.38%, 58.7% and 37.9% respectively for optimization of the response. Confirmation tests were carried out and the percentage error between observed and predicted value of the responses is found to be within acceptable limits, demonstrating that the created models correlates well with the experimental data. Under optimal conditions, utilizing a tungsten carbide tool can prove to be a cost-effective alternative for turning Al-SiCp composite.

Innovative Approaches to Wear Reduction in Horizontal Powder Screw Conveyors: A Design of Experiments-Guided Numerical Study

Numerical simulations play a vital role in the modern engineering industry, especially when faced with interconnected challenges such as particle interactions and the structural integrity of conveyor systems. This article focuses on the handling of materials and emphasizes the importance of using parametric numerical analysis to improve efficiency, reduce wear, and enhance the structural integrity of horizontal screw conveyors. Through the utilization of the Design of Experiments, we systematically investigated critical parameters such as screw pitch, clearance, wear, rotational velocity, and additional structural factors. This examination was carried out within a well-defined parametric framework, utilizing a combination of software tools provided by the Ansys suite and Minitab. The findings demonstrate the effectiveness of the Design of Experiments analysis in achieving improved performance and provide valuable insights for engineers and researchers involved in the design of conveyor systems. Furthermore, this comprehensive approach clarifies how conveyor systems respond to changes in parameters and highlights the complex interaction between transported particles and the conveyor system. We present a detailed analysis that clarifies the complex relationships and dependencies among different parameters, providing engineers and researchers with valuable insights. By understanding the interactions of these factors, the methodology provides not only results but also a strategic framework for advancing conveyor system design and engineering practices.

Multi-source uncertainty propagation and sensitivity analysis of turbine blades with underplatform dampers

Underplatform dampers (UPDs) mitigate turbine blade vibrations in aeroengines through friction dissipation generated by the contact interface. However, in UPD design, uncertainties are often overlooked, including manufacturing discrepancies, excitation forces, and wear factors, leading to suboptimal predictions of structural dynamic responses. This study presents a dynamic model for the blade-UPD system with cyclic symmetric attributes, which simulates uncertainties using statistical methods. An efficient algorithm using adaptive techniques is proposed to construct polynomial chaos expansions (PCE) for precise and efficient uncertainty quantification (UQ) in turbine blades with UPDs. Further, the influence of single/multiple parameter uncertainties on the dynamic characteristics of the blade-UPD is explored. Sobol' indices are then employed to assess the sensitivity of uncertain factors to the vibration reduction properties of UPDs. The findings suggest that the new approach, which offers precise UQ at minimal computational cost, outperforms traditional methods like Ordinary Least Squares (OLS) and Sparse Least Angle Regression (LARS). Observations reveal a significant impact of parameter uncertainties on blade-UPD dynamic responses, which manifest as "resonance bands" and "frequency shifts" in some cases. Sensitivity analysis indicates noticeable variations in Sobol' indices for each uncertainty parameter as the excitation frequency changes. Specifically, the uncertainty in the friction coefficient demonstrates pronounced sensitivity to amplitude when slip occurs at the contact interface. Furthermore, the observed "drop" phenomenon in Sobol' indices is explained.

Shot Peening Effect on Sliding Wear in 0.9% NaCl of Additively Manufactured 17-4PH Steel.

The growing demand for modern steels showing corrosion and tribological resistance has led to their increased use in the production of medical devices. This study analyzed the effect of shot peening on wear resistance in 0.9% NaCl solution of 17-4PH steel produced by direct laser metal sintering (DMLS) technology. The study's novelty relies on revealing the effect of shot peening (SP) surface treatment on the wet sliding wear resistance of 17-4PH steel produced with DMLS. Moreover, in the context of 17-4PH steel application for medical devices, the 0.9% NaCl tribological environment were selected, and SP processes were conducted using steel CrNi shot and ceramic (ZrO2) beads. The up-to-date scientific literature has not identified these gaps in the research. DMLS technology makes it possible to obtain products with complex architectures, but it also faces various challenges, including imperfections in the surface layer of products due to the use of 3D printing technology itself. The chemical and phase composition of the materials obtained, Vickers hardness, surface roughness, and microscopic and SEM imaging were investigated. Tribological tests were carried out using the ball-on-disc method, and the surfaces that showed traces of abrasion to identify wear mechanisms were subjected to SEM analysis. The XRD phase analysis indicates that austenite and martensite were found in the post-production state, while a higher martensitic phase content was found in peened samples due to phase transformations. The surface hardness of the peened samples increased by more than double, and the post-treatment roughness increased by 12.8% after peening CrNi steels and decreased by 7.8% after peening ZrO2 relative to the reference surfaces. Roughness has an identifiable effect on sliding wear resistance. Higher roughness promotes material loss. After the SP process, the coefficient of friction increased by 15.5% and 20.7%, while the wear factor (K) decreased by 25.9% and 32.7% for the samples peened with CrNi steels and ZrO2, respectively. Abrasive and adhesive mechanisms were dominant, featured with slight fatigue. The investigation showed a positive effect of SP on the tribological properties of DMSL 17-4PH.

Statistical analysis of VEXLPE wear against alumina produced by a new 200-station, multidirectional pin-on-disk device.

With low wear rates shown by contemporary bearing materials of total hip prostheses, the standard deviation of wear rate is relatively high. Therefore, large sample sizes are needed for an adequate power of test. Because wear tests take a long time, it is practical to test several samples simultaneously. A new high-capacity, multidirectional wear test device, called the SuperCTPOD-200, was introduced. A 3 million-cycle wear test with an unprecedented sample size of 200 was performed for VEXLPE. The duration of the test was 6 weeks. The wear factor was normally distributed with a mean ± SD of 1.64 × 10-7 mm3/Nm ± 0.22 × 10-7 mm3/Nm (n = 200). The observation that SD was 13.1% of the mean can be useful in power analyses of future tests with other highly cross-linked polyethylenes. Burnishing was the most typical feature on the worn pins, which was in agreement with clinical findings on retrieved acetabular liners. The present study emphasizes statistics that often plays a minor role only in wear studies.

Tribological and rheological performance of friction modifiers with different viscosities

Friction modifier (FM) in the rail/wheel applications is a special lubrication material that could be applied between the top of rail and the tread of wheel. The application of FM brings many benefits to the wheel-rail interface such as reducing noise, alleviating wheel-rail wear and mitigating corrugation. Viscosity is an important parameter to reflect fluid properties of FM materials. In this study, FM samples with different viscosities were prepared by changing the content of sodium carboxymethyl cellulose (CMC). The tribological and rheological performance of these FM samples were explored using the twin-disc testing machine and rotational rheometer. Furthermore, the relationship between the tribological and rheological results were tried to establish. The results showed that the increase in the content of CMC could increase the viscosity of FM and enhance the solid-like characteristic of FM, which could help FM reduce coefficient of adhesion (COA) level and wheel-rail damage. For the FM material developed in this study, the rational applying amount and the range of viscosity were about 15 μL/time and 200 Pa s to 400 Pa s, respectively, considering the factors of wheel-rail adhesion, wear, potential waste and pumping process in the practical application.

Tooth Wear in Older Adults: A Review of Clinical Studies.

Tooth wear is a prevalent dental condition among older adults, leading to pain and adversely affecting aesthetics, functionality, and their overall quality of life. This review aims to update the information on tooth wear in older adults from the past five years and to provide guidance on the clinical management of tooth wear in older adults. A literature search was conducted in three electronic databases, Scopus, Pubmed, and Embase, for English publications from January 2019 to December 2023 on clinical studies with participants aged 65 or above on tooth wear. A total of 307 articles were retrieved and 14 articles were finally included as references for this study. This review highlights the common causes of tooth wear and various risk factors, such as medical conditions, hyposalivation, dietary habits, oral hygiene practices, parafunctional habits, and occlusal factors, associated with tooth wear. It is crucial for oral health care professionals to diagnose and manage tooth wear at an early stage through a risk assessment and a clinical examination to avoid complex restorative procedures. Tooth wear management should prioritize prevention, aiming to control etiological and risk factors while employing non-restorative treatments. Restorative intervention, if indicated, should be simple, minimally invasive, and cost-effective. Tooth wear progression should be monitored regularly to determine if a further intervention is needed. Since the clinical studies on tooth wear in older adults over the past five years are limited and mainly cross-sectional, more interventional clinical studies are warranted to provide more clinical guidance on tooth wear management in older adults.

Properties of ceramic coatings in engine cylinder liners restoration using combined technology

In the course of vehicle operation with internal combustion engines, due to various reasons, defects occur on the cylinder mirror, resulting in the need for repair work to eliminate them. For non-cylinder blocks most often requires replacement with a new block, which is economically very costly. The technologies of liner restoration are very diverse and their application depends on the available equipment and material of the liner. The aim of the work is to develop a new combined technology for the restoration of liners and cylinder blocks regardless of the material for their manufacture. As a technology of restoration of the geometry of the mirror of the liner the method of cold gas dynamic spraying with the use of aluminum powder is considered. Subsequent application of the plasma electrolytic oxidation (PEO) technology makes it possible to obtain on the mirror a ceramic coating with thickness of 80-100 microns, which is sufficient for long-term operation of the internal combustion engine. On the basis of GZ-195N liner the technology of cylinder mirror restoration was worked out and the process of plasma electrolytic oxidation (PEO) was carried out. Research has shown that the hardening of the coating occurs to the depth of 100 microns required by the technology. The wear resistance of the coating exceeds the wear resistance of the reference sample, its wear factor is 1.27 times less than that of the reference pair. The possibility of using the technology of aluminum coating by cold spray on any metal makes the combined technology of cylinder liner repair applicable to achieve the desired result - to restore the performance of the cylinder block or liner and increase their wear resistance. The obtained positive results require the development of industrial technology of combined coating and experimental testing on a running engine.

Associated Risk Factors with Tooth Wear in Patients Attending Private Dental Hospital in Karachi: A Cross-Sectional Study

Background: Tooth wear is non-carious enamel and dentinal destruction with multi-factorial etiology affecting oral health-related quality of life. Identification of risk factors and their prevention are crucial in the management of such cases. Objective: To determine risk factors associated with tooth wear in patients attending Hamdard University Dental Hospital. Methods: A descriptive cross-sectional study was conducted from 1st February to 31st July 2023. Non-probability consecutive sampling was done. Patients with tooth wear were identified according to Smith and Knight Criteria of tooth wear. Patients with tooth wear were interviewed on a modified questionnaire to identify further associated risk factors. Data was entered and analyzed in SPSS version 22. Descriptive statistics were used for categorical variables. Univariate and multivariate logistic regression were used to determine predictive factors associated with tooth wear. Crude and adjusted Odds ratios with 95% confidence intervals were used to measure association. P-values < 0.05 were considered statistically significant. Results: Overall, 755 patients were examined and participated in the study accounting for a 98% response rate. 62.6% were males and 37.4% were females with an age range of 18-65 years. Tooth Wear was present in 75.6% of participants with 58.8% erosion, 31.5% attrition, and 6.1% abrasion cases.3.5% of patients demonstrated more than one type of TW. Carbonated drinks showed a higher risk of tooth wear, followed by bruxism, gastric problems, and aggressive tooth brushing. Conclusion: Associated risk factors of tooth wear should be given due consideration to implementing patient education and preventive strategies to preserve dental health.

Istraživanje uticaja delaminacije izazvane bušenjem i habanja alata na preostalu čvrstoću u polimernim nanokompozitima

Drilling-induced delamination, fractures, debonding, tool wear, and matrix fuzzing all reduce the residual strength of polymer composites. The novelty of the present studies lies in incorporating nano-fillers Graphene and Montmorillonite Clay at a 2% weight percentage for the toughening matrix to minimize drilling-induced residual stresses and tool wear. Combining the matrix's thermal and mechanical properties with fibers reduces fibrous composite macro and micro residual stresses. Interlaminar shear strength rose by 16%-23% and fracture toughness by 22% using nanofillers, minimizing drilling-induced crack delamination and composite tensile strength deterioration. Nanofillers increased hole laminate tensile strength retention and time to failure. Tool wear and delamination factors rose at the hole exit with increased drilled holes but improved at the entry by 16%. This study shows the intricate link between composite material composition, process variables, and structural integrity in drilling-exposed composites.

ИССЛЕДОВАНИЕ ИЗНОСОСТОЙКОСТИ ГИЛЬЗ ЦИЛИНДРОВ, ВОССТАНОВЛЕННЫХ КЕРАМИЧЕСКИМ ПОКРЫТИЕМ

The results of the study of the workability and wear resistance of the combined coating of the restored cylinder liners obtained by applying a layer of aluminum powder to the cast-iron base by cold gas-dynamic spraying with subsequent treatment by microarc oxidation were presented. (Research purpose) The research purpose is a comparative analysis of the tribotechnical properties of the conjugations "sleeve coated with cold gas-dynamic spraying and treatment with microarc oxidation-counter-sample 100Cr6" and "sleeve (SH25 in the delivery state)-counter-sample 100Cr6" (reference pairing). (Materials and methods) Conducted a study of the workability of materials of the reference and reconstructed conjugations according to RD 50-662-88 "Guidelines. Methods of experimental evaluation of frictional compatibility of materials of friction conjugations". Comparative bench tests were performed on the wear resistance of the reference and restored conjugates according to GOST 23.224-86 "Ensuring the wear resistance of products. Methods for assessing the wear resistance of restored parts". (Results and discussion) The optimal modes of long-term operation and the limits of the interface operability were determined during the stepwise loading of the reference and restored tribo-couplings. The run-in coefficient and the wear factor of the couplings were calculated. It was found that the restored coupling "sleeve coated with cold gas-dynamic spraying and microarc oxidation treatment-counter-sample 100Cr6" has similar run-in rates with the reference coupling, and its wear resistance exceeds the wear resistance of the reference coupling by more than two times. (Conclusions) High indicators of workability and wear resistance of the restored interface "sleeve coated with cold gas-dynamic spraying and microarc oxidation treatment-counter-sample 100Cr6" in comparison with the reference sleeve (from SCH25 in the state of delivery) provide an increase in its durability and indicate the expediency of using the combined method in the restoration of cylinder liners.

ABRASIVE WEAR BEHAVIOR OF FUNCTIONALLY GRADED AIB2/AI COMPOSITE

Functionally graded composites (FGM) can combine high surface wear resistance and high toughness. For this reason, it has been seen to be preferred in many regions, especially in the defense and maritime sectors, in recent years. This study is an experimental study on the investigation of the wear properties of functionally graded AlB2 boride reinforced composite materials, which can be an alternative in the manufacturing of ship machinery parts exposed to repeated loads and wear. This study aims to increase the industrial usability of the boron element, which has strategic importance for our country. Pin-On-Disk technique and abrasive wear method were used to determine the wear properties of composites. In the wear tests, a total of 5 factors consisting of wear factors such as the region of the composite (% reinforcement ratio), abrasive particle diameter, application load, sliding distance and sliding speed were selected as test parameters with 3 levels. In wear tests, the "Taguchi Experimental Design" method was used. As a result of the study, it was seen that the hardness and wear resistance of aluminum increased with the addition of AlB2 into the aluminum matrix. It was observed that the load had an effect of 33.98%, the abrasive particle diameter had an effect of 31.68% and the AlB2 reinforcement ratio had a 10.73% effect on the wear resistance of the composites. As a result of the study, linear equations predicting 'wear resistance in different conditions' were obtained.

Iron Oxide and Hydroxide Speciation in Emissions of Brake Wear Particles from Different Friction Materials Using an X-ray Absorption Fine Structure

Iron (Fe), the main component of non-exhaust particulates, is known to have variable health effects that depend on the chemical species of iron. This study characterized the possible contribution of iron oxides and hydroxides to airborne brake wear particles under realistic vehicle driving and braking conditions with different brake pad friction materials. We found significant differences in wear factors and PM10 and PM2.5 emissions between non-asbestos organic (NAO) and European performance (ECE) brake pads. Iron was the dominant contributor to PM10 and PM2.5 brake wear particles for both NAO and ECE. The iron concentration ratio in the particle mass (PM) was comparable to the disc-to-pads ratio measured by wear mass. The fact that magnetite, which is of interest with respect to health effects, was less abundant in NAO than in ECE suggested that tribo-oxidations occurred in NAO. Metallic iron is generated not only from abrasive wear but also from tribo-chemical reduction with magnetite as the starting material. We found that there were differences in PM emissions between brake friction materials, and that the phase transformations of iron differed between friction materials. These differences were apparent in the distribution of iron oxides and hydroxides. Heat, tribo-oxidation, and tribo-reduction are intricately involved in these reactions.

Method for Determining the Factor of Dual Wedge-Shaped Wear of Composite Brake Pads for Freight Wagons

Method for Determining the Factor of Dual Wedge-Shaped Wear of Composite Brake Pads for Freight Wagons

Wear Evolution on PVD Coated Cutting Tool Flank and Rake Explained Considering Stress, Strain and Strain-Rate Dependent Material Properties

Impact loads developed on a tool cutting edge when milling into a workpiece material are prevailing metrics for explaining coating fatigue failure and the subsequent tool-wear evolution. For predicting related stress and strain fields in the compound coating-substrate, stress, strain, and strain-rate, dependent material properties are required. The attainment of such data is briefly described in the paper. Considering these data, the occurring strains in the cutting edge at various entry impact durations, i.e., strain rates, were calculated and compared with fatigue-critical strains. In this way, the wear phenomena causing the coating failure on the flank and rake during milling were clarified. The attained results were also correlated to corresponding ones in turning, where the dynamic loads of the cutting edge are comparably negligible. The conducted investigations showed that the fatigue-critical strains strongly diminish, when the relevant strain rates increase; thus, leading to a remarkable tool-life reduction. This happens, because the increase of the strain-rate restricts the time for the dislocations movements; thus, regions with stress concentrations occur, deteriorating the material ductility, increasing its brittleness, and diminishing the fatigue critical strains. In cutting operations, where the coating fatigue is the main wear factor, the tool-life can be predicted considering these phenomena. In the paper, relevant experimental analytical procedures are introduced.

Wear mechanism analysis and its effect on the cutting process of CBN tools during laser ultrasonically assisted turning of tungsten carbide

Tungsten carbide, known for its high hardness and brittleness, presents a challenge in traditional processes due to severe tool wear and shortened tool life, impacting machining efficiency. This paper introduces a hybrid turning method – laser ultrasonically assisted turning (LUAT) – for precision and efficient machining of tungsten carbide. LUAT combines tool ultrasonic vibration with laser-induced workpiece heating to enhance the cutting performance of tungsten carbide. Thermal modeling is utilized to determine suitable LUAT parameters. Comparative experiments are conducted to assess the advantages of LUAT in enhancing tool performance and improving surface quality. Results indicate that, compared to traditional turning, ultrasonically assisted turning, and laser assisted turning, LUAT significantly reduces tool wear and enhances tool lifespan. In LUAT of tungsten carbide, the tool wear on the rake face exhibits long strips parallel to the tool edge, while the flank face presents triangular wear land, shallow pits, and grooves. Investigation into wear characteristics and mechanisms of cubic boron nitride (CBN) tools reveals that adhesion, oxidation, and diffusion are major wear factors, with chipping and tipping being abnormal wear patterns for CBN tools. Intensified tool wear elevates cutting forces and cutting temperatures, deteriorating the surface quality of tungsten carbide turning. However, LUAT mitigates these effects, resulting in lower cutting forces and temperatures within the same wear time, improving surface quality.

Taux de survie à 20 ans d’une prothèse totale de genou postérostabilisée mono-opérateur dans une population asiatique

IntroductionAs life expectancy has improved, the potential number of revision candidates is also expected to increase among patients who have undergone a total knee arthroplasty (TKA). The longevity of modern posterior stabilized knee prostheses after 20 years of use has not been well documented, especially in Asian populations that require a deeper flexion range due to a floor-based lifestyle. Hypothesis(1) The implant longevity regarding mechanical failures such as aseptic loosening and polyethylene (PE) wear would vary over a longer follow-up depending on the age groups; and (2) there would be unique risk factors for revision surgery in an Asian TKA cohort. Material and methodsWe conducted this age-stratified survival analysis in a consecutive series of 368 NexGen Legacy Posterior Stabilized (LPS) TKAs performed by a single surgeon. These cases were divided into four age groups (< 60 years, early 1960s, late 1960s, and ≥ 70 years). The implant longevity against aseptic mechanical failures was calculated using the Kaplan-Meier method. The revision surgery risk was evaluated using postoperative factors including a deep flexion capability(> 135°), and postoperative mechanical alignments. ResultsOverall survivorship was significantly lower in the youngest groups than other groups (Log-rank test, p=0.001). The cumulative 20-year implant longevity was more than 95% in the two oldest groups, but less than 60% in the youngest group. It was notable that the post-TKA implant longevity was not apparent up to 10 years between the age groups (p=0.073∼0.458). Aseptic loosening was observed with an earlier onset (3.1 to 18.9 years) trend than PE wear (9.8∼17.9 years), with most cases arising in the youngest groups. Flexion limitation and varus alignment were significant risks to aseptic loosening and PE wear (Cox proportional hazard regression: p=0.001 and 0.045, respectively). DiscussionA younger age (< 60 years), inability of postoperative deep flexion, and varus alignment were significant risk factors for aseptic loosening and PE wear after modern PS design in this Asian cohort. The difference in postoperative longevity affected by these factors was not obvious during the first 10 years but emerged over a second decade. Level of proofIII; retrospective cohort study.

Acetabular erosion after bipolar hip hemiarthroplasty for femoral neck fracture in elderly patients: a retrospective study.

The choice between total hip arthroplasty (THA) and hemiarthroplasty (HA) to treat displaced femoral neck fractures, particularly among the elderly, is still controversial. Acetabular erosion consists of a late multifactorial process that may happen after hip HA resulting in significant postoperative burden. This study aims to investigate the impact of acetabular erosion progress after hip HA in patients over 70 years old. This is a 5-year (2013-2018) retrospective study including consecutive series of patients >70 years who were treated with bipolar hip HA for femoral neck fractures. Patients were categorised into 3 groups for analysis (A = 70-75 years, B = 75-80 years, C = >80 years). The study enrolled a total number of 813 patients who met the inclusion criteria. We assessed acetabular erosion through radiological examinations and measured functional deterioration using the modified Harris Hip Score (mHHS) at 6 and 12 months follow-up. Our comprehensive investigation extended over a maximum period of 5 years. The correlation of patients' characteristics and HA features on erosion progress was assessed. There were no significant differences in sex distribution, injury side, BMI, ASA score, bipolar head diameter, mHHS and leg-length discrepancy among the groups (p > 0.05). During the follow-up period, acetabular erosion with consequential conversion to THA was observed in 6.13%, 4.22% and 1.96% for Groups A, B and C respectively (p = 0.009). A statistically significant difference of acetabular erosion was observed in Group A compared to patients of Group C. Age constitutes a significant factor of acetabular wear after HA in the elderly. The higher rate of acetabular wear in patients <75 years suggests that THA is a more viable option, as HA is for patients >80 years old.

A follow-up study of the severe occlusal surface wear of implant-supported full-arch prostheses

Objective: To evaluate the severe occlusal surface wear of implant-supported full-arch prostheses, and to explore the risk factors affecting the severe occlusal surface wear of implant-supported full-arch prostheses. Methods: Five hundred and thirty-five patients who received implant-supported fixed complete dental prostheses or implant-overdentures and completed at least one follow-up 3 months after the delivery of definitive prostheses were enrolled from October 1994 to October 2021 in this retrospective cohort study. The information on demographics, implants, definitive prostheses, and related outcomes was collected. Cox proportional hazard regression model was adopted to analyze the risk factors of the severe wear of occlusal surfaces in implant-supported full-arch prostheses. Univariate analysis was performed on the factors that may affect the severe wear of occlusal surfaces, and the parameters of P<0.10 in univariate analysis were included in multivariate analysis to explore the risk factors affecting the severe wear of occlusal surfaces in implant-supported full-arch prostheses. Results: Severe wear of the posterior occlusal surfaces was detected in 114 prostheses with a duration of 61.4 (33.3, 89.4) months. 13 cases occurred≤2 years after the delivery of definitive prostheses, 44 cases>2 years and≤5 years, 44 cases>5 years and≤10 years, and the other 13 cases>10 years. There was no significant difference in the average time of severe occlusal surface wear between implant-supported fixed complete dental prostheses and implant-overdentures in the maxilla (Z=-1.03, P=0.303). However, in the mandible, it was 48.2 (31.2, 80.2) and 79.2 (51.3, 119.1) months respectively, which was statistically significant (Z=-2.93, P=0.003). Cox proportional hazard regression model showed opposed fixed dentition, bruxism, and posterior resin occlusal surfaces were risk factors (P<0.05) affecting the severe wear of the occlusal surfaces. Conclusions: Severe occlusal surface wear was clinically common with the prolonged application of implant-supported full-arch prostheses. Prostheses opposed to fixed dentition, in patients with bruxism, and made of posterior resin materials were at higher risk of severe occlusal surface wear on the posterior artificial teeth. Regular follow-up, patients' behavior guidance, and clinicians' appropriate intervention were necessary to manage this complication.

Effect of Caesalpinia decapetala on the Dry Sliding Wear Behavior of Epoxy Composites

The present research investigates the wear characteristics of an epoxy composite reinforced with a novel Caesalpinia decapetala (CD) shell. The CD is available abundantly worldwide, especially in Ethiopia, particularly in East and West Oromia near West Harar. The composite specimens were processed in the open mould casting technique by varying the vol.% of CD in 10, 20, and 30. EDS is used to evaluate the important elements present in the CD. The density of composites increases with the increase in the content of CD, while the void content estimations reveal good control over the composite fabrication. The wear response of composites is investigated by varying the sliding distance and load and by maintaining a fixed velocity (5 m/s). At a 5 km slide distance and 50 N load, the 30 vol.% Caesalpinia decapetala composition depicts better wear resistance and friction coefficient than other compositions. Experimental results are used to envisage the ideal wear factors and to assess the influence of parameters over the two wear objectives, wear rate and CoF. The grey relational analysis- (GRA-) coupled artificial neural network (ANN) hybrid technique was employed for the prediction and validation. It has been observed that a trivial error of 0.49% amidst GRA and ANN estimation is observed.