scholarly journals Effect of Enamel Prism Decussation and Chemical Composition on the Biomechanical Behavior of Dental Tissue: A Theoretical Approach to Determine the Loading Conditions to Which Modern Human Teeth are Adapted

2008 ◽  
Vol 291 (2) ◽  
pp. 175-182 ◽  
Author(s):  
Daisuke Shimizu ◽  
Gabriele A. Macho
Keyword(s):  
Chemical Composition ◽  
Theoretical Approach ◽  
Modern Human ◽  
Loading Conditions ◽  
Dental Tissue ◽  
Human Teeth ◽  
Biomechanical Behavior ◽  
Enamel Prism

scholarly journals Sea otter dental enamel is highly resistant to chipping due to its microstructure

2014 ◽  
Vol 10 (10) ◽  
pp. 20140484 ◽  
Author(s):  
Charles Ziscovici ◽  
Peter W. Lucas ◽  
Paul J. Constantino ◽  
Timothy G. Bromage ◽  
Adam van Casteren
Keyword(s):  
Dental Enamel ◽  
Modern Human ◽  
Sea Otter ◽  
Human Teeth ◽  
Human Enamel ◽  
Chip Size ◽  
Fossil Hominins ◽  
On Chip ◽  
Fossil Hominin ◽  
Enamel Prism

Dental enamel is prone to damage by chipping with large hard objects at forces that depend on chip size and enamel toughness. Experiments on modern human teeth have suggested that some ante-mortem chips on fossil hominin enamel were produced by bite forces near physiological maxima. Here, we show that equivalent chips in sea otter enamel require even higher forces than human enamel. Increased fracture resistance correlates with more intense enamel prism decussation, often seen also in some fossil hominins. It is possible therefore that enamel chips in such hominins may have formed at even greater forces than currently envisaged.

In Vitro Experimental Testing of a Cervical Implanted Unit

2008 ◽  
Vol 399 ◽  
pp. 205-210
Author(s):  
Dan Ioan Stoia ◽  
Nicolae Faur ◽  
Mirela Toth-Taşcău ◽  
Laurenţiu Culea
Keyword(s):  
Experimental Testing ◽  
Metal Structure ◽  
Anatomical Structure ◽  
Loading Conditions ◽  
Physiological Conditions ◽  
Biomechanical Behavior ◽  
Physiological Loading ◽  
Extreme Load ◽  
Symmetrical Loading

The paper describes the biomechanical behavior of a cervical implanted unit (CIU) in two conditions: during the physiological and extreme loading. In order to reveal these behaviors, the anatomical structure composed by the C2 and C3 cervical vertebras was implanted using a plate-screws metal structure. The implant was design to perform dynamical, by allowing longitudinal, transversal and rotational movements. The physiological conditions were simulated by the pulsatory negative loading, while the extreme loading was simulated by the alternant symmetrical loading. The tests reveal two behaviors: the durability of the CIU in the physiological loading conditions and the failure of the structure under extreme load.

scholarly journals Air Quality in a Dental Clinic during Er:YAG Laser Usage for Cavity Preparation on Human Teeth—An Ex-Vivo Study

2021 ◽  
Vol 18 (20) ◽  
pp. 10920
Author(s):  
Angeliki Karveli ◽  
Ioannis G. Tzoutzas ◽  
Panagiotis Ioannis Raptis ◽  
Emmanouil-George C. Tzanakakis ◽  
Eleftherios Terry R. Farmakis ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Er:Yag Laser ◽  
Ex Vivo ◽  
Working Environment ◽  
Dental Clinic ◽  
Dental Tissue ◽  
Cavity Preparation ◽  
Human Teeth ◽  
Limit Values

Chemical air pollution in dental clinics consists of the emission of gases and particulate matter (PM), both generated by dental equipment and tooth tissues. One basic application of Erbium Laser devices is cavity preparation on human teeth due to its strong affinity to water and hydroxyapatite. The objective of this study was the evaluation of indoor air quality during the application of an Er:YAG laser, as a dentin removal instrument, in a Dental Clinic. Particulate Matter (PM) was measured using the standard method of EN legislation. In order to measure total Volatile Organic compounds (VOCs), a portable monitor was used. In the first experiment, PM10 and PM2.5 concentrations were increased by approximately 10 and 15 times, respectively. From the second experiment it can be concluded that neither of the measured particle concentrations exceeded the recommended indoor limit values while windows were open, although laser influence was still detectable. Within the limitations applied herein, it was found that Er:YAG laser activity for hard dental tissue removal was associated with high PM and TVOCs concentration values in the working environment, under insufficient or no ventilation. Physical ventilation in the aforementioned setting proved to be an important key factor in improving air quality, as both PM and TVOCs concentrations decreased significantly.

scholarly journals Theoretical approach to modeling the combustion process in turbine engines fuelled by alternative aviation fuels containing various components/biocomponents

2017 ◽  
Vol 171 (4) ◽  
pp. 245-249
Author(s):  
Andrzej KULCZYCKI
Keyword(s):  
Mathematical Model ◽  
Chemical Composition ◽  
Mathematical Models ◽  
Combustion Chamber ◽  
Theoretical Approach ◽  
Alternative Fuels ◽  
Combustion Process ◽  
Turbine Engines ◽  
Alternative Aviation Fuels ◽  
Combustion Processes

The aim of this paper is presentation of the possibility of combustion processes modelling so that to better describe the influence of fuels chemistry on fuels combustion. This is important for prediction the behaviour of different alternative fuels in processes in combustion chamber. Currently used mathematical models do not sufficiently take into account the influence of fuels chemical composition on combustion process. The idea of new mathematical model is proposed in this paper. The paper presents the main assumptions of this model and the results of its preliminary verification using MiniJetRig.

scholarly journals Synchrotron IR-microspectroscopy-based visualization of molecular and chemical interactions between dental cement, biomimetic composite and native dental tissue

2019 ◽  
pp. 71-78 ◽  
Author(s):  
DL Goloshchapov ◽  
V.M. Kashkarov ◽  
Yu.A. Ippolitov ◽  
I.Yu. Ippolitov ◽  
Jitraporn Vongsvivut ◽  
...  
Keyword(s):  
Calcium Hydroxyapatite ◽  
Human Tooth ◽  
Hard Tissue ◽  
Dental Tissue ◽  
Human Teeth ◽  
Dental Cement ◽  
Biomimetic Material ◽  
Hard Dental Tissue ◽  
Calcium Source ◽  
Ir Microspectroscopy

The low affinity of composite materials for the hard tissue of human teeth poses a challenge to restorative dentists. This study was undertaken to explore molecular and chemical characteristics of the interface between the dental cement, the buffer layer formed from a next generation biomimetic material that mimics the organic mineral composition of human enamel and dentin, and the intact native hard dental tissue. Seven plane-parallel dental slices were analyzed using synchrotron IR microspectroscopy. The obtained absorption spectra of functional molecular groups were organized into cluster maps. This allowed us to identify the intact tissue, the adhesive agent and the biomimetic layer at their interface and to localize and measure concentrations of functional groups involved in the integration of the biomimetic composite into the hard tissue of the human tooth. The proposed biomimetic material is based on nanocrystal carbonate-substituted calcium hydroxyapatite synthesized from a biogenic calcium source and a complex of basic polar amino acids copying the composition of the human tooth and can form a functional bond with hard dental tissue.

A COMPARATIVE ANALYSIS OF THE EFFECTS OF TWO AUGMENTERS ON THE SENSITIVITY OF VERTEBRAL BIOMECHANICAL BEHAVIOR IN VERTEBROPLASTY

2020 ◽  
Vol 20 (04) ◽  
pp. 2050007
Author(s):  
SUN YUEWAN ◽  
WANG DONGMEI ◽  
SUN JINGCHUAN ◽  
LIU ANMIN ◽  
SHI JIANGANG
Keyword(s):  
Bone Cement ◽  
Clinical Results ◽  
Vertebral Compression Fractures ◽  
Fe Model ◽  
Loading Conditions ◽  
Osteoporotic Vertebral Compression Fractures ◽  
Fe Method ◽  
Biomechanical Behavior ◽  
Fitting Method ◽  
Biomechanical Parameters

The treatment of osteoporotic vertebral compression fractures (OVCFS) by transvertebral bone graft and augmentation (TBGA) has achieved satisfactory clinical results, but its biomechanical effects are not clear. The purpose of this study was to investigate the biomechanical effects of TBGA and compare the biomechanical sensitivity of the augmenter used in TBGA — a cylindrical enhancement device (CED) with bone cement. The finite element (FE) model of healthy segments T11-L3 (M1) was built, and two other models with L1 augmentation (M2, M3) were established to simulate CED and bone cement treatment, respectively. The stress and displacement distribution of the three models under five physiological loads were calculated and analyzed by the FE method. Based on the results, the sensitivities of biomechanical parameters to the degree of osteoporosis (DO) and loads were analyzed by linear fitting method using dummy variables. With the increase of DO, the CED is superior to bone cement in preventing the fractures of the augmented vertebral and the adjacent vertebral under the set loading conditions. Simulating TBGA method, the model 2 with L1 reconstructed was closer to the normal T11-L3 model in terms of sensitivity of stress and displacement under different loading conditions.

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