scholarly journals Quantitative three-dimensional microtextural analyses of tooth wear as a tool for dietary discrimination in fishes

2012 ◽  
Vol 9 (74) ◽  
pp. 2225-2233 ◽  
Author(s):  
Mark Purnell ◽  
Ole Seehausen ◽  
Frietson Galis
Keyword(s):  
Three Dimensional ◽  
Stomach Contents ◽  
Isotopic Analysis ◽  
Tooth Wear ◽  
Model Organisms ◽  
Resource Exploitation ◽  
Microwear Analysis ◽  
Trophic Resource ◽  
Tooth Surfaces ◽  
Trophic Analysis

Resource polymorphisms and competition for resources are significant factors in speciation. Many examples come from fishes, and cichlids are of particular importance because of their role as model organisms at the interface of ecology, development, genetics and evolution. However, analysis of trophic resource use in fishes can be difficult and time-consuming, and for fossil fish species it is particularly problematic. Here, we present evidence from cichlids that analysis of tooth microwear based on high-resolution (sub-micrometre scale) three-dimensional data and new ISO standards for quantification of surface textures provides a powerful tool for dietary discrimination and investigation of trophic resource exploitation. Our results suggest that three-dimensional approaches to analysis offer significant advantages over two-dimensional operator-scored methods of microwear analysis, including applicability to rough tooth surfaces that lack distinct scratches and pits. Tooth microwear textures develop over a longer period of time than is represented by stomach contents, and analyses based on textures are less prone to biases introduced by opportunistic feeding. They are more sensitive to subtle dietary differences than isotopic analysis. Quantitative textural analysis of tooth microwear has a useful role to play, complementing existing approaches, in trophic analysis of fishes—both extant and extinct.

scholarly journals 3D Method for Occlusal Tooth Wear Assessment in Presence of Substantial Changes on Other Tooth Surfaces

2020 ◽  
Vol 9 (12) ◽  
pp. 3937
Author(s):  
Nikolaos Gkantidis ◽  
Konstantinos Dritsas ◽  
Christos Katsaros ◽  
Demetrios Halazonetis ◽  
Yijin Ren
Keyword(s):  
Morphological Changes ◽  
Low Cost ◽  
Three Dimensional ◽  
Standard Technique ◽  
Tooth Wear ◽  
Absolute Difference ◽  
Perfect Agreement ◽  
True Value ◽  
Tooth Surfaces ◽  
3D Superimposition

Early diagnosis and timely management of tooth or dental material wear is imperative to avoid extensive restorations. Previous studies suggested different methods for tooth wear assessment, but no study has developed a three-dimensional (3D) superimposition technique applicable in cases where tooth surfaces, other than the occlusal, undergo extensive morphological changes. Here, we manually grinded plaster incisors and canines to simulate occlusal tooth wear of varying severity in teeth that received a wire retainer bonded on their lingual surfaces, during the assessment period. The corresponding dental casts were scanned using a surface scanner. The modified tooth crowns were best-fit approximated to the original crowns using seven 3D superimposition techniques (two reference areas with varying settings) and the gold standard technique (GS: intact adjacent teeth and alveolar processes as superimposition reference), which provided the true value. Only a specific technique (complete crown with 20% estimated overlap of meshes), which is applicable in actual clinical data, showed perfect agreement with the GS technique in all cases (median difference: −0.002, max absolute difference: 0.178 mm3). The outcomes of the suggested and the GS technique were highly reproducible (max difference < 0.040 mm3). The presented technique offers low cost, convenient, accurate, and risk-free tooth wear assessment.

Wear and microwear on the teeth of a moose (Alces alces) population in Manitoba, Canada

1986 ◽  
Vol 64 (11) ◽  
pp. 2467-2479 ◽  
Author(s):  
William G. Young ◽  
Therese M. Marty
Keyword(s):  
Tooth Loss ◽  
Microscopic Analysis ◽  
Tooth Wear ◽  
Incisor Tooth ◽  
Electron Microscopic ◽  
Tooth Structure ◽  
Microwear Analysis ◽  
Anterior Teeth ◽  
Scanning Electron Microscopic ◽  
Scanning Electron Microscopic Analysis

A group of wild moose from Manitoba, Canada, were documented as having excessive tooth wear. Replicas of one incisor tooth were collected from 16 individuals and from 19 controls for comparison by volumetric and scanning electron microscopic analysis. All animals were aged from tooth cementum lines. Tooth replicas were cast from silicone rubber impressions in epoxy resin and sputter coated with gold. Tooth wear with age was compared statistically by measuring crown height, percent tooth loss, interfacet distance, and facet area on the incisors. The unique pattern of wear on the anterior teeth of affected moose was described. In affected animals, crown heights were significantly reduced and percent tooth loss was excessive. Microwear analysis found that an abrasive agent, acting predominantly in a lingual to labial direction, had been responsible for loss of enamel and dentine incisally and interproximally, and on the facial and lingual surfaces to a lesser extent. Interdental facets became involved by vertical abrasion. Control teeth showed fewer but coarser scratches and only approached the pattern of wear found in affected moose in a few individuals in old age. The loss of tooth structure would lead to diminished cropping efficiency and damage to the periodontium.

First evidence for tooth-tooth occlusion in a ctenochasmatid pterosaur from the Early Cretaceous Jehol Biota

2021 ◽  
pp. SP521-2021-141
Author(s):  
Chang-Fu Zhou ◽  
Xinyue Wang ◽  
Jiahao Wang
Keyword(s):  
Early Cretaceous ◽  
Feeding Strategy ◽  
Three Dimensional ◽  
Tooth Wear ◽  
First Record ◽  
Jehol Biota ◽  
Content Type ◽  
Dimensional Reconstruction ◽  
Supplementary Material ◽  
Ct Data

AbstractCtenochasmatid pterosaurs flourished and diversified in the Early Cretaceous Jehol Biota. Here, a partial mandible of Forfexopterus is described based on a three-dimensional reconstruction using high-resolution X-ray Computed Tomography (CT) data. The first nine pairs of functional teeth of the rostral dentition revealed along with their replacements. The functional teeth are evenly arranged with a tooth density of 2.2 teeth/cm. The tooth crown is distinctly reduced from its base to the tip, and framed by two weak ridges, possibly as a pair of vestigial carinae. The replacement teeth are sharp and pointed, and have erupted slightly against the medial surface of the functional teeth. Surprisingly, tooth wear is observed in this specimen, the first record of tooth-tooth occlusion in ctenochasmatids. The wear facets exhibit high-angled lingual and lower-angled labial facets, implying a tooth-tooth occlusion in pterosaur clade. This discovery indicates that the Jehol ctenochasmatids possibly employed a more active feeding strategy than other filter-feeding pterosaurs (e.g. Ctenochasma, Pterodaustro, Gnathosaurus).Supplementary material at https://doi.org/10.6084/m9.figshare.c.5722060

scholarly journals Effect of the presence of orthodontic brackets on intraoral scans

2020 ◽  
Vol 91 (1) ◽  
pp. 98-104
Author(s):  
Sung-Ja Kang ◽  
Youn-Ju Kee ◽  
Kyungmin Clara Lee
Keyword(s):  
Cross Sections ◽  
Tooth Movement ◽  
Vertical Section ◽  
Three Dimensional ◽  
Orthodontic Brackets ◽  
Horizontal Section ◽  
Arch Width ◽  
Tooth Surfaces ◽  
The Cross ◽  
Width Measurements

ABSTRACT Objectives The need for intraoral scanning in the presence of brackets has increased for monitoring tooth movement during orthodontic treatment. The purpose of this study was to evaluate the effect of orthodontic brackets bonded to tooth surfaces on intraoral scans. Materials and Methods Intraoral scans were performed in 30 patients using both iTero and Trios scanners before and after bonding of the brackets. The two sets of intraoral scans of each patient and intraoral scans with and without brackets were superimposed using a best-fit algorithm, and three-dimensional (3D) surface analysis was performed. In each superimposition, discrepancies in the 3D axes and arch-width measurements in the incisor and molar regions were compared. In addition, the range of distortion around the brackets was evaluated on the cross sections of each superimposition. Results The overall discrepancies between the intraoral scans with and without brackets were within 0.30 mm. The arch-width discrepancies in the molar region were greater than those in the incisor region, but the differences were not statistically significant (P = .972 for iTero; P = .960 for Trios). The cross sections of the superimposed intraoral scans with and without brackets showed that the deviations were within 0.40 mm in the horizontal section and within 0.35 mm in the vertical section around the brackets. Conclusions The results of this study indicate that the accuracy of intraoral scans, even in the presence of brackets, is clinically acceptable, and the regions beyond 0.50 mm around the brackets should be used for superimposition on images without brackets.

Sliding Wear Calculation in Spur Gears

1993 ◽  
Vol 115 (3) ◽  
pp. 493-500 ◽  
Author(s):  
Shifeng Wu ◽  
H. S. Cheng
Keyword(s):  
Wear Rate ◽  
Sliding Wear ◽  
Elastohydrodynamic Lubrication ◽  
Tooth Wear ◽  
Spur Gears ◽  
Gear Teeth ◽  
Tooth Surfaces ◽  
Wear Calculation ◽  
Determining Factor ◽  
Wear Region

In gear applications where precipitous tooth failure mode such as scoring or scuffing has been avoided, “normal” wear becomes a life-determining factor. In this paper, sliding wear in spur gears, including the considerations of gear dynamics and rough-elastohydrodynamic lubrication, is analyzed. Formulas for equivalent wear rate and tooth wear profile along the line of action are derived. Results show that most materials are removed from both the addendum and dedendum tooth surfaces, and that the highest wear occurs at the beginning of an engagement. This high wear region corresponds to the root of the driving (pinion) teeth and the tip of the driven (gear) teeth. These analytical results correlate well with the practical evidences in AGMA documentation.

Stress Analysis of Spherical Gear Sets

2009 ◽  
Author(s):  
Li-Chi Chao ◽  
Chung-Biau Tsay
Keyword(s):  
Gear Tooth ◽  
Three Dimensional ◽  
Contact Analysis ◽  
Design Parameters ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Contact Points ◽  
Tooth Surfaces ◽  
Loaded Tooth Contact Analysis ◽  
Spherical Gear

The spherical gear is a new type of gear proposed by Mitome et al. [1]. Different from that of the conventional spur or helical gear sets, the spherical gear set can allow variable shaft angles and large axial misalignments without gear interference during the gear drive meshing [1, 2]. Geometrically, the spherical gear has two types of gear tooth profiles, the concave tooth and convex tooth. In practical transmission applications, the contact situation of a spherical gear set is very complex. To obtain a more realistic simulation result, the loaded tooth contact analysis (LTCA) has been performed by employing the finite element method (FEM). According to the derived mathematical model of spherical gear tooth surfaces, an automatic meshes generation program for three-dimensional spherical gears has been developed. Beside, tooth contact analysis (TCA) of spherical gears has been performed to simulate the contact points of the spherical gear set. Furthermore, the contact stress contours of spherical gear tooth surfaces and bending stress of tooth roots have been investigated by giving the design parameters, material properties, loadings and boundary conditions of spherical gears.

Correlation of Tooth Surface Wear Prediction With Experimental Results of Spur and Helical Gears in Commercial Vehicle Transmissions

2013 ◽  
Author(s):  
Carlos H. Wink
Keyword(s):  
Commercial Vehicle ◽  
Gear Tooth ◽  
Numerical Procedure ◽  
Tooth Wear ◽  
Experimental Results ◽  
Analytical Models ◽  
Tooth Surface ◽  
Wear Prediction ◽  
Vehicle Transmissions ◽  
Tooth Surfaces

Gear pair dynamic loads can increase significantly with involute profile changes caused by wear resulting in vibration and noise issues. Tooth stresses such as root stress and contact stress can also increase reducing gear life. Wear prediction is important during the design phase to minimize the effects of worn tooth surfaces on product performance. Some analytical models have been proposed to predict gear tooth wear; however published correlations of predictions with experimental results are still limited, especially from the gear industry. But they are vital to build confidence in analytical tools. This paper presents a correlation of wear predictions with experimental results of spur and helical gear pairs that are used in commercial vehicle transmissions. Four different gear lubricants were considered, and also three tooth finishes, grinding, honing, and shaving. A modified Archard’s wear model was used for wear predictions. The model combines a gear contact model and an iterative numerical procedure to account for tooth surface changes. Wear coefficients were determined from experiments. The correlation between predictions and dynamometer testing data was established.

scholarly journals Comparative three-dimensional kinematics of the hindlimb for high-speed bipedal and quadrupedal locomotion of lizards

1999 ◽  
Vol 202 (9) ◽  
pp. 1047-1065 ◽  
Author(s):  
D.J. Irschick ◽  
B.C. Jayne
Keyword(s):  
Morphological Variation ◽  
High Speed ◽  
Three Dimensional ◽  
Distinct Species ◽  
Model Organisms ◽  
Locomotor Performance ◽  
Lizard Species ◽  
Quadrupedal Locomotion ◽  
Foot Posture ◽  
Sprinting Speed

Although lizards have been model organisms for testing locomotor performance and in ecomorphological studies, the limb movements of lizards during high-speed locomotion are poorly understood. Thus, we quantified the three-dimensional kinematics of the hindlimb, body and tail for five morphologically distinct species of lizard during steady-speed locomotion near maximum sprinting speed (2–5 m s-1). The kinematics of different species had little multivariate overlap. More than half of the strides of all species had digitigrade foot posture, but the frequency of using digitigrade foot posture varied among species. The combination of digitigrade foot posture and large foot size of the lizards contributed substantially to the high values of hip height. For each species, different suites of kinematic variables distinguished bipedal from quadrupedal strides. Interspecific morphological variation did not correspond globally to variation in kinematics, although lizard species with elongated hindlimbs took longer strides than species with shorter hindlimbs. The Froude numbers and relative stride lengths of all lizards running near maximal speeds were large compared with those reported previously for other vertebrates.

scholarly journals A three-dimensional habitat for C. elegans environmental enrichment

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245139
Author(s):  
Aurélie Guisnet ◽  
Malosree Maitra ◽  
Sreeparna Pradhan ◽  
Michael Hendricks
Keyword(s):  
Environmental Enrichment ◽  
Expression Patterns ◽  
Three Dimensional ◽  
Model Organisms ◽  
Initial Assessment ◽  
C Elegans ◽  
Laboratory Conditions ◽  
In The Wild ◽  
And Behaviors ◽  
Microbial Environment

As we learn more about the importance of gene-environment interactions and the effects of environmental enrichment, it becomes evident that minimalistic laboratory conditions can affect gene expression patterns and behaviors of model organisms. In the laboratory, Caenorhabditis elegans is generally cultured on two-dimensional, homogeneous agar plates abundantly covered with axenic bacteria culture as a food source. However, in the wild, this nematode thrives in rotting fruits and plant stems feeding on bacteria and small eukaryotes. This contrast in habitat complexity suggests that studying C. elegans in enriched laboratory conditions can deepen our understanding of its fundamental traits and behaviors. Here, we developed a protocol to create three-dimensional habitable scaffolds for trans-generational culture of C. elegans in the laboratory. Using decellularization and sterilization of fruit tissue, we created an axenic environment that can be navigated throughout and where the microbial environment can be strictly controlled. C. elegans were maintained over generations on this habitat, and showed a clear behavioral bias for the enriched environment. As an initial assessment of behavioral variations, we found that dauer populations in scaffolds exhibit high-frequency, complex nictation behavior including group towering and jumping behavior.

scholarly journals A System for the Acquisition and Analysis of Three-Dimensional Data Describing Dental Morphology

2018 ◽  
Vol 17 (3) ◽  
pp. 70-74 ◽  
Author(s):  
Pingzhou Liu ◽  
Sarbin Ranjitkar ◽  
John A. Kaidonis ◽  
Grant C. Townsend ◽  
Lindsay C. Richards
Keyword(s):  
Three Dimensional ◽  
Tooth Wear ◽  
Technical Note ◽  
Personal Computers ◽  
Dental Morphology ◽  
3D Data ◽  
Coefficients Of Variation ◽  
Potential Applications ◽  
Derived Data ◽  
3D Profilometer

Accurate, reproducible three-dimensional (3D) data provide an important contribution to our ability to describe, compare and understand dental morphology but the existing technology is often expensive or has technical limitations. Recently available, inexpensive 3D profilometers interfaced with standard personal computers offer the potential to overcome some of these problems. This technical note describes a system that uses a 3D profilometer and purpose written software to analyse changes in dental morphology resulting from tooth wear. The validity of the derived data was determined by comparing data derived from scans of objects of known dimensions with calculated volumes. These differences were less than 10% from objects that were difficult to scan because of their geometry and were commonly less than 5%. The reproductibility, expressed as intra- and inter-observer coefficients of variation, was less than 1%. The potential applications of systems of this type are outlined.

Sign in / Sign up

Export Citation Format

Share Document