Linking tooth shape to strike mechanics in the Boa constrictor

2021 ◽  
Author(s):  
William G Ryerson ◽  
Tate Van Valkenburg
Keyword(s):  
Prey Capture ◽  
Posterior Teeth ◽  
Capture Process ◽  
Tooth Shape ◽  
Regional Specialization ◽  
Anterior Teeth ◽  
Boa Constrictor ◽  
Rodent Prey ◽  
Definition Of ◽  
And Function

Abstract Snakes, with the obvious exception of the fangs, are considered to lack the regional specialization of tooth shape and function that are exemplified by mammals. Recent work in fishes has suggested the definition of homodont and heterodont are incomplete without a full understanding of the morphology, mechanics, and behavior of feeding. We investigated this idea further by examining changes in tooth shape along the jaw of Boa constrictor and integrating these data with the strike kinematics of boas feeding on rodent prey. We analyzed the shape of every tooth in the skull, from a combination of anesthetized individuals and CT scanned museum specimens. For strike kinematics, we filmed eight adult boas striking at previously killed rats. We determined the regions of the jaws that made first contact with the prey, and extrapolated the relative positions of those teeth at that moment. We further determined the roles of all the teeth throughout the prey capture process, from the initiation of the strike until constriction began. We found that teeth in the anterior third of the mandible are the most upright, and that teeth become progressively more curved posteriorly. Teeth on the maxilla are more curved than on the mandible, and the anterior teeth are more linear or recurved than the posterior teeth. In a majority of strikes, boas primarily made contact with the anterior third of the mandible first. The momentum from the strike caused the upper jaws and skull to rotate over the rat. The more curved teeth of the upper jaw slid over the rat unimpeded until the snake began to close its jaws. In the remaining strikes, boas made contact with the posterior third of both jaws simultaneously, driving through the prey and quickly retracting, ensnaring the prey on the curved posterior teeth of both jaws. The curved teeth of the palatine and pterygoid bones assist in the process of the swallowing.

Reabilitação total com porcelanas em paciente acometido por amelogênese imperfeita

2021 ◽  
Vol 10 (38) ◽  
pp. 21-27
Author(s):  
Weider de Oliveira Silva ◽  
Gabriela Barbosa de Sá ◽  
Tarcísio Pinto ◽  
Gil Montenegro ◽  
Ismael Lucas Pinto
Keyword(s):  
Tooth Enamel ◽  
Tooth Wear ◽  
Dental Tissue ◽  
Posterior Teeth ◽  
Developmental Abnormalities ◽  
Anterior Teeth ◽  
Complex Development ◽  
And Function ◽  
Clinical Problems

Amelogenesis imperfecta (AI) is a disorder of genetic origin, linked to the amelogenin gene, which presents developmental abnormalities in the quantity and quality of tooth enamel. The main clinical problems are the extensive loss of dental tissue, occlusal problems, impaired aesthetics, tooth sensitivity and gingival inflammation. This study described a clinical case and the approach in the treatment of a patient with AI, with gingival plastic surgery, porcelain crowns on the posterior teeth, porcelain veneers on the anterior teeth and application of botulinum toxin to correct the gingival smile. AI is an anomaly with complex development and early diagnosis is essential for the conduct and success of the case, to improve aesthetics and function, preserving the characteristic tooth wear.

scholarly journals Aesthetic Treatment In Patient With Fractures Of Maxillary Central Incisor Teeth

DENTA ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 89
Author(s):  
Sinta Puspita
Keyword(s):  
Root Resorption ◽  
Temporomandibular Disorder ◽  
Psychological Trauma ◽  
Mandibular Movement ◽  
Posterior Teeth ◽  
Maxillary Central Incisor ◽  
Anterior Teeth ◽  
Anterior Guidance ◽  
Conservative Faculty ◽  
And Function

<p><strong><em>Background : </em></strong><em>A common objective of anterior restorative dentistry is to establish anterior guidance between the maxillary and mandibular anterior teeth to disclude the posterior teeth during protrusive mandibular movement. Fracture anterior teeth leads to psychological trauma, along with functional and esthetic debilitations. Healthy anterior teeth play an important role of protecting the posterior teeth during excursive mandibular movement. The contour and shape of the labial surface are important for esthetic purpose; the palatal surface morphology is critical for harmonious function. Premature contact in palatal surface restoration is considered as contributing factor to temporomandibular disorder (TMD) symptoms. <strong>Purpose : </strong>Improve aesthetics and function of the patient's anterior teeth. <strong>Case : </strong>Male, 17 years old with poor aesthetic because of fracture anterior teeth 4 years ago. <strong>Case Management : </strong>Root canal treatment, treatment of root resorption, fiber post, custom post, indirect veener, zirconia crown and enameloplasty. <strong>Result : </strong>Better aesthetic and get the optimum function of his teeth.</em></p><p><em> </em></p><p><strong><em>Keyword:</em></strong><em> Aesthetic treatment, anterior fracture, zirconia crown, indirect venner</em></p><p><em> </em></p><p><strong><em>Correspondence:</em></strong><em> </em><em>Sinta Puspita</em><strong>, </strong><em>Department of </em>Conservative, Faculty of  Dentistry, Hang Tuah University, <em>Universitas Hang Tuah, Arif Rahman Hakim 150 Surabaya, </em><em>Phone</em><em> 031-5945864, 5912191,  Email:</em> <em><a href="mailto:[email protected]">[email protected]</a></em></p>

Kontrast und Wissen

2009 ◽  
Vol 54 (1) ◽  
pp. 69-102
Author(s):  
Robin Rehm
Keyword(s):  
19Th Century ◽  
Edmund Husserl ◽  
Specific Knowledge ◽  
Max Scheler ◽  
Black And White ◽  
Black Circle ◽  
Black Cross ◽  
Definition Of ◽  
And Function ◽  
The 19Th Century

Kasimir Malewitschs suprematistische Hauptwerke ›Schwarzes Quadrat‹, ›Schwarzer Kreis‹ und ›Schwarzes Kreuz‹ von 1915 setzen sich aus schwarzen Formen auf weißem Grund zusammen. Der Typus des Schwarzweißbildes weist überraschende Parallelen zu den bildlichen Wahrnehmungsinstrumenten auf, die vom ausgehenden 18. bis Anfang des 20. Jahrhunderts in den Experimenten der Farbenlehre, physiologischen Optik und Psychologie verwendet worden sind. Die vorliegende Studie untersucht diese Parallelen in drei Schritten: Zunächst erfolgt eine allgemeine Charakterisierung des Schwarzweißbildes mit Hilfe des Kontrastbegriffs von Edmund Husserl. Des weiteren wird die Entstehung und Funktion des schwarzweißen Kontrastbildes in den Wissenschaften des 19. Jahrhunderts typologisch herausgearbeitet. Unter Berücksichtigung des Wissensbegriffs von Max Scheler wird abschließend die Spezifik des Wissens eruiert, das die Schwarzweißbilder sowohl in der Malerei Malewitschs als auch in den genannten Wissenschaften generieren. Malevich’s main Suprematist works, such as ›Black Square‹, ›Black Circle‹, and ›Black Cross‹ from 1915, consist of black shapes on white ground. Surprisingly this series of shapes strongly resembles scientific black-and-white images used for research on colour theory, physiological optics, and psychology throughout the 19th century. This paper examines the parallels between Malevich’s paintings and the scientific drawings in three steps: It first characterizes black-and-white images in general, using Edmund Husserl’s definition of the term ›contrast‹. Secondly, the paper investigates the development and function of black-and-white images as tools of perception in the sciences. It finally discusses the specific knowledge generated through Malevich’s art and through scientific black-and-white images, following Max Scheler’s phenomenological identification of knowledge.

John among the Apocalypses

2020 ◽  
Author(s):  
Benjamin E. Reynolds
Keyword(s):  
Gospel Of John ◽  
Central Place ◽  
Reception History ◽  
Genre Theory ◽  
Synoptic Gospels ◽  
Book Of Revelation ◽  
Distinctive Features ◽  
History Of ◽  
Definition Of ◽  
And Function

The central place of revelation in the Gospel of John and the Gospel’s revelatory telling of the life of Jesus are distinctive features of John when compared with the Synoptic Gospels; yet, when John is compared among the apocalypses, these same features indicate John’s striking affinity with the genre of apocalypse. By paying attention to modern genre theory and making an extensive comparison with the standard definition of “apocalypse,” the Gospel of John reflects similarities with Jewish apocalypses in form, content, and function. Even though the Gospel of John reflects similarities with the genre of apocalypse, John is not an apocalypse, but in genre theory terms, John may be described as a gospel in kind and an apocalypse in mode. John’s narrative of Jesus’s life has been qualified and shaped by the genre of apocalypse, such that it may be called an “apocalyptic” gospel. Understanding the Fourth Gospel as “apocalyptic” Gospel provides an explanation for John’s appeal to Israel’s Scriptures and Mosaic authority. Possible historical reasons for the revelatory narration of Jesus’s life in the Gospel of John may be explained by the Gospel’s relationship with the book of Revelation and the history of reception concerning their writing. An examination of Byzantine iconographic traditions highlights how reception history may offer a possible explanation for reading John as “apocalyptic” Gospel.

Physicianship and the Rebirth of Medical Education

2018 ◽  
Author(s):  
J. Donald Boudreau ◽  
Eric Cassell ◽  
Abraham Fuks
Keyword(s):  
Medical Education ◽  
Educational Process ◽  
Medical Attention ◽  
Patient Centeredness ◽  
Goals Of Medicine ◽  
The Subject ◽  
Definition Of ◽  
And Function ◽  
William Osler ◽  
The Relationship

This book reimagines medical education and reconstructs its design. It originates from a reappraisal of the goals of medicine and the nature of the relationship between doctor and patient. The educational blueprint outlined is called the “Physicianship Curriculum” and rests on two linchpins. First is a new definition of sickness: Patients know themselves to be ill when they cannot pursue their purposes and goals in life because of impairments in functioning. This perspective represents a bulwark against medical attention shifting from patients to diseases. The curriculum teaches about patients as functional persons, from their anatomy to their social selves, starting in the first days of the educational program and continuing throughout. Their teaching also rests on the rock-solid grounding of medicine in the sciences and scientific understandings of disease and function. The illness definition and knowledge base together create a foundation for authentic patient-centeredness. Second, the training of physicians depends on and culminates in development of a unique professional identity. This is grounded in the historical evolution of the profession, reaching back to Hippocrates. It leads to reformulation of the educational process as clinical apprenticeships and moral mentorships. “Rebirth” in the title suggests that critical ingredients of medical education have previously been articulated. The book argues that the apprenticeship model, as experienced, enriched, taught, and exemplified by William Osler, constitutes a time-honored foundation. Osler’s “natural method of teaching the subject of medicine” is a precursor to the Physicianship Curriculum.

scholarly journals Comparison of the accuracy of intraoral scans between complete-arch scan and quadrant scan

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Youn-Gyeong Moon ◽  
Kyung-Min Lee
Keyword(s):  
Third Molar ◽  
Careful Consideration ◽  
Missing Teeth ◽  
Posterior Teeth ◽  
Anterior Teeth ◽  
Posterior Quadrant ◽  
Left Posterior ◽  
The Right ◽  
Best Fit ◽  
Posterior Area

Abstract Objective To compare the accuracy of complete-arch scans and quadrant scans obtained using a direct chairside intraoral scanner. Material and methods Intraoral scans were obtained from 20 adults without missing teeth except for the third molar. Maxillary and mandibular complete-arch scans were carried out, and 4 quadrant scans for each arch were performed to obtain right posterior, right anterior, left anterior, and left posterior quadrant scans. Complete-arch scans and quadrant scans were compared with corresponding model scans using best-fit surface-based registration. Shell/shell deviations were computed for complete-arch scans and quadrant scans and compared between the complete-arch scans and each quadrant scans. In addition, shell/shell deviations were calculated also for each individual tooth in complete-arch scans to evaluate factors which influence the accuracy of intraoral scans. Results Complete-arch scans showed relatively greater errors (0.09 ~ 0.10 mm) when compared to quadrant scans (0.05 ~ 0.06 mm). The errors were greater in the maxillary scans than in the mandibular scans. The evaluation of errors for each tooth showed that the errors were greater in posterior teeth than in anterior teeth. Comparing the right and left errors, the right side posterior teeth showed a more substantial variance than the left side in the mandibular scans. Conclusion The scanning accuracy has a difference between complete-arch scanning and quadrant scanning, particularly in the posterior teeth. Careful consideration is needed to avoid scanning inaccuracy for maxillary or mandibular complete-arch, particularly in the posterior area because a complete-arch scan might have potential error than a quadrant scan.

scholarly journals Dual-section versus conventional archwire for en-masse retraction of anterior teeth with direct skeletal anchorage: a finite element analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ryo Hamanaka ◽  
Daniele Cantarella ◽  
Luca Lombardo ◽  
Lorena Karanxha ◽  
Massimo Del Fabbro ◽  
...  
Keyword(s):  
Finite Element ◽  
Tooth Movement ◽  
Occlusal Plane ◽  
Skeletal Anchorage ◽  
Element Analysis ◽  
Posterior Teeth ◽  
Posterior Portion ◽  
Anterior Teeth ◽  
Retraction Force ◽  
En Masse Retraction

Abstract Background The aim of this study is to compare the biomechanical effects of the conventional 0.019 × 0.025-in stainless steel archwire with the dual-section archwire when en-masse retraction is performed with sliding mechanics and skeletal anchorage. Methods Models of maxillary dentition equipped with the 0.019 × 0.025-in archwire and the dual-section archwire, whose anterior portion is 0.021 × 0.025-in and posterior portion is 0.018 × 0.025-in were constructed. Then, long-term tooth movement during en-masse retraction was simulated using the finite element method. Power arms of 8, 10, 12 and 14 mm length were employed to control anterior torque, and retraction forces of 2 N were applied with a direct skeletal anchorage. Results For achieving bodily movement of the incisors, power arms longer than 14 mm were required for the 0.019 × 0.025-in archwire, while between 8 and 10 mm for the dual-section archwire. The longer the power arms, the greater the counter-clockwise rotation of the occlusal plane was produced. Frictional resistance generated between the archwire and brackets and tubes on the posterior teeth was smaller than 5% of the retraction force of 2 N. Conclusions The use of dual-section archwire might bring some biomechanical advantages as it allows to apply retraction force at a considerable lower height, and with a reduced occlusal plane rotation, compared to the conventional archwire. Clinical studies are needed to confirm the present results.

scholarly journals Alpha-Tocopherol Metabolites (The Vitamin E Metabolome) and Their Interindividual Variability during Supplementation

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 173
Author(s):  
Desirée Bartolini ◽  
Rita Marinelli ◽  
Danilo Giusepponi ◽  
Roberta Galarini ◽  
Carolina Barola ◽  
...  
Keyword(s):  
Vitamin E ◽  
Target Genes ◽  
Interindividual Variability ◽  
Pregnane X Receptor ◽  
Alpha Tocopherol ◽  
Therapeutic Interventions ◽  
Intrinsic Variability ◽  
Blood Leukocytes ◽  
Definition Of ◽  
And Function

The metabolism of α-tocopherol (α-TOH, vitamin E) shows marked interindividual variability, which may influence the response to nutritional and therapeutic interventions with this vitamin. Recently, new metabolomics protocols have fostered the possibility to explore such variability for the different metabolites of α-TOH so far identified in human blood, i.e., the “vitamin E metabolome”, some of which have been reported to promote important biological functions. Such advances prompt the definition of reference values and degree of interindividual variability for these metabolites at different levels of α-TOH intake. To this end, a one-week oral administration protocol with 800 U RRR-α-TOH/day was performed in 17 healthy volunteers, and α-TOH metabolites were measured in plasma before and at the end of the intervention utilizing a recently validated LC-MS/MS procedure; the expression of two target genes of α-TOH with possible a role in the metabolism and function of this vitamin, namely pregnane X receptor (PXR) and the isoform 4F2 of cytochrome P450 (CYP4F2) was assessed by immunoblot in peripheral blood leukocytes. The levels of enzymatic metabolites showed marked interindividual variability that characteristically increased upon supplementation. With the exception of α-CEHC (carboxy-ethyl-hydroxychroman) and the long-chain metabolites M1 and α-13′OH, such variability was found to interfere with the possibility to utilize them as sensitive indicators of α-TOH intake. On the contrary, the free radical-derived metabolite α-tocopheryl quinone significantly correlated with the post-supplementation levels of α-TOH. The supplementation stimulated PXR, but not CYP4F2, expression of leucocytes, and significant correlations were observed between the baseline levels of α-TOH and both the baseline and post-supplementation levels of PXR. These findings provide original analytical and molecular information regarding the human metabolism of α-TOH and its intrinsic variability, which is worth considering in future nutrigenomics and interventions studies.

Full-Mouth Rehabilitation for a Patient With Dentinogenesis Imperfecta: A Clinical Report

2014 ◽  
Vol 40 (5) ◽  
pp. 593-600 ◽  
Author(s):  
Sompop Bencharit ◽  
Michael B. Border ◽  
C. Russell Mack ◽  
Warren C. Byrd ◽  
John T. Wright
Keyword(s):  
Dental Implants ◽  
Computer Aided Design ◽  
Genetic Disorder ◽  
Asian Woman ◽  
Clinical Report ◽  
Dentinogenesis Imperfecta ◽  
Posterior Teeth ◽  
Anterior Teeth ◽  
Computer Aided ◽  
Full Mouth Rehabilitation

Dentinogenesis imperfecta (DI) is a genetic disorder affecting the structural integrity of the dentin that can result in weakened dentin. The affected teeth, especially posterior teeth, often need to be extracted due to severe wear or fracture. This frequently yields a loss of posterior occlusion and occlusal vertical dimension. Besides wear and fracture, anterior teeth often have an unesthetic appearance because of discoloration. Current treatments of choice, including composite bonding restorations and, more recently, all-ceramic restorations, are typically suggested to preserve the remaining teeth and tooth structure. However, there are a limited number of studies on dental implants in patients with DI. The effectiveness of dentin bonding and dental implants in patients with DI is not known. This clinical report describes a 32-year-old Asian woman with DI who underwent full-mouth rehabilitation. The posterior occlusion, mostly in the molar areas, was restored with dental implants and ceramometal restorations. The anterior teeth and premolars were restored with bonded lithium disilicate glass-ceramic pressed veneers and crowns made with computer-aided design/computer-aided manufacturing. This case demonstrates that restoring functional occlusion and esthetics for a patient with DI can be completed successfully using contemporary implant therapy and adhesive dentistry.

scholarly journals Patients’ general satisfaction with the appearance of anterior maxillary teeth

2017 ◽  
Vol 74 (6) ◽  
pp. 520-525 ◽  
Author(s):  
Vlatka Lajnert ◽  
Daniela Kovacevic-Pavicic ◽  
Hrvoje Pezo ◽  
Aleksandra Stevanovic ◽  
Tatjana Jovic ◽  
...  
Keyword(s):  
Dental Plaque ◽  
Negative Influence ◽  
Cross Sectional ◽  
Age And Gender ◽  
Tooth Shape ◽  
General Satisfaction ◽  
Anterior Teeth ◽  
Dental Appearance ◽  
And Gender ◽  
The Impact

Background/Aim. Dental appearance plays an important role in practically all personal social interactions. The main factors that define the dental appearance are tooth colour, shape and position, quality of restoration, and the general position of the teeth in arch, especially in the anterior region. The aim of this study was to evaluate the impact of dental status (tooth shape, fracture, dental and prosthetic restorations and presence of plaque) on patient''s satisfaction with the dental appearance, controlling for the age and gender. Methods. A total of 700 Caucasian subjects (439 women) aged 18?86 (median 45 years) participated in the cross-sectional study. Study included clinical examination and self-administrated questionnaire based on selfperceived aesthetics and satisfaction with the appearance of their maxillary anterior teeth. Results. A regression analysis demonstrated that presence of dental plaque, tooth fracture, composite fillings and crowns had significant independent contribution and were negative predictors of satisfaction with teeth appearance. Participants with presence of plaque on upper teeth (p < 0.001), fractures (p = 0.005), composite fillings (p < 0.001) and crowns (p = 0.032) were less satisfied than those without it. Model explains 12% or variance of general satisfaction with the appearance of maxillary frontal teeth (p < 0.001) and the major contributors are composite fillings (5.3%) and plaque (3.2%). Tooth shape, age and gender were not significant predictors of satisfaction. Conclusion. Satisfaction with the teeth appearance is under the influence of many factors with significant negative influence of presence of dental plaque, fractures, composite restorations, and crowns.

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