The aim of this study was to explore and compare the results of occlusal load application to cusp-replacing composite restorations, studied by means of finite element (FE) analysis and in vitro load tests. A three-dimensional (3D) FE model was created with a set up similar to an in vitro load test that assessed the fatigue resistance of upper premolars with buccal cusp-replacing resin composite restorations. Occlusal load was applied to two geometries (with and without palatal cuspal coverage), and the tooth-restoration interface and composite material stresses were calculated. Subsequently, safety factors were calculated by dividing the material strength values by the obtained stresses. The highest safety factors were observed for the restorations with cuspal coverage. This was consistent with the load test, in which cuspal coverage led to higher fracture resistance. Furthermore, the FE analysis predicted that failure of the tooth-restoration interface is more likely than failure of the composite material. Correspondingly, the load test showed predominantly adhesive failures of the restorations. Although the described test methods did not lead to a complete understanding of the failure mechanism, it can be concluded that the FE analysis provides additional information with regard to the differences in fracture behaviour of these types of restorations.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1111/j.1600-0722.2005.00233.x | DOI Listing |
Int J Occup Saf Ergon
January 2025
Department of Industrial and Systems Engineering, Gyeongsang National University, Republic of Korea.
Soldering is common in electrical product manufacturing, but the task load in small units is unquantified. Therefore, this study aimed to establish the occurrence of task load due to soldering work, analyzing the effects of age and sex among workers in small manufacturing units. The task load of 102 soldering workers from four small-scale manufacturing units was assessed using the National Aeronautics and Space Administration task load index (NASA-TLX) questionnaire, covering six dimensions: physical demand, mental demand, temporal demand, effort, performance and frustration.
View Article and Find Full Text PDFFront Sports Act Living
January 2025
School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, Canada.
Introduction: The bilateral deficit (BLD) is a reduction in the amount of force during a bilateral task vs. the total force from the unilateral limbs performing the same task. We quantified the BLD during an upper body Wingate Anaerobic Test (WAnT) and evaluated the influence of sex and load on the BLD in force.
View Article and Find Full Text PDFHum Reprod Open
December 2024
Vrije Universiteit Brussel (VUB), Brussels Health Campus/Faculty of Medicine and Pharmacy, Research Group Genetics, Reproduction and Development , Laarbeeklaan 103, 1090 Brussels, Belgium.
Study Question: Is there an association between different mitochondrial DNA (mtDNA) genotypes and female infertility or ovarian response, and is the appearance of variants in the oocytes favored by medically assisted reproduction (MAR) techniques?
Summary Answer: Ovarian response was negatively associated with global non-synonymous protein-coding homoplasmic variants but positively associated with haplogroup K; the number of oocytes retrieved in a cycle correlates with the number of heteroplasmic variants in the oocytes, principally with variants located in the hypervariable (HV) region and rRNA loci, as well as non-synonymous protein-coding variants.
What Is Known Already: Several genes have been shown to be positively associated with infertility, and there is growing concern that MAR may facilitate the transmission of these harmful variants to offspring, thereby passing on infertility. The potential role of mtDNA variants in these two perspectives remains poorly understood.
Wilderness Environ Med
January 2025
Department of Emergency Medicine, Denver Health Hospital, Denver, CO.
In this case report we describe evaluating a patient for a traumatic knee arthrotomy using ultrasound in a resource-limited medical clinic at the base of a ski area. A 23-y-old female presented with a laceration superior to the patella of the left leg. On examination, the wound tracked deep, and providers had concern for traumatic arthrotomy.
View Article and Find Full Text PDFBiomech Model Mechanobiol
January 2025
Department of Mechanical Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70503, USA.
This research demonstrates a systematic curve fitting approach for acquiring parametric values of hyperelastic constitutive models for both healthy and enzymatically mediated degenerated cartilage to facilitate finite element modeling of cartilage. Several widely used phenomenological hyperelastic constitutive models were tested to adequately capture the changes in cartilage mechanics that vary with the differential/unequal abundance of matrix metalloproteinases (MMPs). Trauma and physiological conditions result in an increased production of collagenases (MMP-1) and gelatinases (MMP-9), which impacts the load-bearing ability of cartilage by significantly deteriorating its extracellular matrix (ECM).
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!