Introduction
Molecular aspects
Primary epithelial band
Developmental stages
Morphologic stages
Physiologic processes
Defects in development
Root formation
Development of teeth in-vitro
References
Amelogenesis is the formation of enamel. During amelogenesis, the ameloblast (enamel-forming cells) undergo various stages i.e the life cycle of ameloblast.
For more content check out my blog: www.rkharitha.wordpress.com "a little about everything dental"
Introduction
Molecular aspects
Primary epithelial band
Developmental stages
Morphologic stages
Physiologic processes
Defects in development
Root formation
Development of teeth in-vitro
References
Amelogenesis is the formation of enamel. During amelogenesis, the ameloblast (enamel-forming cells) undergo various stages i.e the life cycle of ameloblast.
For more content check out my blog: www.rkharitha.wordpress.com "a little about everything dental"
Why do these remnants proliferate?
The origin of epithelial odontogenic neoplasms, hamartomas and cysts is inextricably bound up with a discussion of the parent cells of these lesions.
Epithelial Remnants may develop into Cysts, Tumors, and Hamartomas.
Dentinogenesis/certified fixed orthodontic courses by Indian dental academyIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
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For first year dental student, i got this from the internet.. Hope this can help u guys understand more about the tooth development.. Btw, good luck for minitest OB tomorrow.. No sacrifice, no victory!
Why do these remnants proliferate?
The origin of epithelial odontogenic neoplasms, hamartomas and cysts is inextricably bound up with a discussion of the parent cells of these lesions.
Epithelial Remnants may develop into Cysts, Tumors, and Hamartomas.
Dentinogenesis/certified fixed orthodontic courses by Indian dental academyIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
For first year dental student, i got this from the internet.. Hope this can help u guys understand more about the tooth development.. Btw, good luck for minitest OB tomorrow.. No sacrifice, no victory!
Developmental disturbances in structure of teeth Amelogenesis imperfecta /en...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Política petrolera, fracking y resistencias: La soberanía energética como hor...AIDA_Americas
Presentación de Felipe Gutiérrez, comunicador social e investigador del Observatorio Petrolero Sur (OPSur), en el seminario virtual "El avance del fracking en América Latina: Herramientas para prevenirlo y detenerlo", realizado el 8 de julio de 2016.
¿Que es el fracking? ¿Cuáles son sus impactos?AIDA_Americas
Presentación de Héctor Herrera, abogado de la Asociación Interamericana para la Defensa del Ambiente (AIDA), en el seminario virtual "El avance del fracking en América Latina: Herramientas para prevenirlo y detenerlo", realizado el 8 de julio de 2016.
The presentation discusses about tooth enamel in detail including its formation, characteristics, structure and histological features along with its clinical considerations. It is well supported with diagrams for better understanding of the text.
Suggestions and feedback will be well appreciated.
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Amelogenesis is a process of enamel formation. Enamel is the hardest calcified matrix of the body .it is translucent &varies in colour from light yellow to grey white, it also varies in thickness from max. of approx. 2.5mm.The cells responsible for formation of enamel is ameloblast , are lost as the tooth erupts into oral cavity &hence enamel cannot renew itself .The development of tooth is divided into bud ,cap ,early bell stage & late bell stage. Enamel formation begins in the bell stage. The fully formed enamel consist of approx.. 96% of mineral & 4% organic material and water.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
The initiation of tooth development begins at 37 days of development
with formation of a continuous horseshoe-band of thickened epithelium
in the location of upper and lower jaws – Primary Epithelial Band
Dental lamina appears as a thickening
of the oral epithelium adjacent to
condensation of ectomesenchyme
20 areas of enlargement or knobs
appear, which will form tooth buds
for the 20 primary teeth
Not all will appear at the same time.
The first to develop are those of the
anterior mandible region
At this early stage the tooth buds
have already determined their crown morphology
Successional lamina: lamina from
which permanent teeth develop
The dental lamina begins to function
at 6th prenatal week and continues to
15th year of birth (3rd molar)
Tooth development is a continuous process, however can be
divided into 3 stages:
1. Bud Stage
2. Cap Stage
3. Bell Stage
4. Hertwigs epithelial root sheath and root formation
The bud stage is represented by the first epithelial incursion into the ectomesenchyme of the jaw.
The epithelial cells show little if any change in shape or function.
The supporting ectomesenchymal cells are packed closely beneath and around the epithelial bud. As the epithelial bud continues to proliferate into the ectomesenchyme, cellular density increases immediately adjacent to the epithelial outgrowth.
This process is classically referred to as a condensation of the ectomesenchyme.
The epithelium of the dental lamina separated from the underlying ectomesenchyme by basement membrane.
Bud stage is characterized by rounded, localized growth of
epithelium surrounded by proliferating mesenchymal cells,which are packed closely beneath and around the epithelial buds
The transition from bud to cap marks the onset of morphologic differences between tooth germs that give rise to different types of teeth.
Differential cellular division in the epithelial bud initiates a change in shape so that now the epithelial outgrowth assumes a more complex outline with a flattened internal portion along which the mesenchymal condensation densifies.
As the tooth bud grows larger, it drags along with it part of the dental lamina; thus from that point on, the developing tooth is tethered to the dental lamina by an extension called the lateral lamina.
At this early stage of tooth development, identifying the formative elements of the tooth and its supporting tissues is already possible.
The epithelial outgrowth, which superficially resembles a cap sitting on a ball of condensed ectomesenchyme , is still referred to widely as the dental organ but actually should be called the enamel organ, because it eventually will form the enamel of the tooth. Henceforth, the term enamel organ is used.
Condensation of the ectomesenchyme immediately subjacent to the tooth bud caused by lack of extracellular matrix secretion by the cells thus preventing separation.
A Brief Description about the development of teeth. Understanding the process of tooth development is of particular importance for the dentist; as developmental disturbances may occur at any stage of this process resulting in different types of tooth anomalies.
Tooth development can be classified either based on morphology or histology
Morphological stages:
Bud stage
Cap stage
Bell stage:
* Early
* Advanced
Physiological stages:
Initiation
Proliferation
Histodifferentiation
Morphodifferentiation
Apposition
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
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NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
2. Amelogensis is a two step process when enamel first forms, it
mineralizes partially to approximately 30٪. As the organic matrix breaks
down and is removed, crystals grow wider and thicker until the full
thickness of enamel layer has been formed to attain greater than 96٪
mineral content. The process of amelogeneis is under cellular control and
the associated cells undergo significant morphologic changes throughout
amelogensis reflecting their evolving physiologic activity.
Enamel formation begin at early crown stage of tooth
development and involves the differentiation of the cells of the
inner enamel epithelium first at the tips of cusp and incisal
edge. Ameloblasts secrete matrix proteins and are responsible
for creating and maintaining an extracellular environment
favorable to mineral deposition. This epithelial cell exhibits a
unique life cycle characterized by progressive phenotype
changes that reflect its primary activity at various times of
enamel's formation.
3. Amelogensis has been divided into :
•Morphogenic phase:- in this phase the inner enamel epithelia, are low columnar or
cuboidal, with large centrally located nucleus. IEE close to the undifferentiated mesenchymal
cells of dental papilla interact with these cells to determined the shape of the crown
(morphodifferentiation). Mitochondria and other cytoplasmic components are scattered
throughout the cells.
•Differentiation phase:- in this stage the IEE differentiate into pre ameloblasts, they
elongate and their nuclei shift proximally toward the stratum intermedium. The cytoplasmic
organells aggregate at the distal side of the cell (secretory end of the cells). During ameloblasts
differentiation, proximal and distal junctional complex appear between them. These junctional
complex play an important role in amelogenesis by tightly holding together ameloblasts and
determining at different times what may, and what may not, pass between them to enter or leave
the enamel.
Presecretory stage
4. Secretory stage
When the first layer of dentin is formed the preameloblast become ameloblasts. The cell
become highly columnar, nucleus at proximal end, cytoplasm fill with synthetic
organells like RER, mitochondria, Golgi apparatus, secretory vesicles, and ribosomes.
The secretory stage begins with the formation of thin layer of enamel matrix opposite to
the dentin (rodless enamel).
The secretory end of ameloblasts becomes pyramidal in shape forming
a process called Tomes' process which is responsible for secretion and
orientation of enamel rods and their crystals.
At this stage ameloblasts synthesis and secrete enamel matrix which
consist of proteins like amelogenin, enamelin, ameloblastin, tuftelin,
amelin, these proteins matrix form about 66%. About 25-30% minerals
which are hydroxyapatite crystals of enamel matrix which secreted by
ameloblasts at the same time. The ameloblasts where secrete enamel
matrix, it retard back word toward the enamel organ, and it secret the
whole enamel matrix at one time.
5. Maturation stage
•Transitional phase:- after full thickness of immature enamel has formed, ameloblasts
undergo significant morphological involving a reduction in height of the ameloblasts
and decrease in their volume and organelle content. Ameloblasts undergo programmed
cell death (apoptosis). Approximately 25% of the ameloblasts die during transition
phase, and another 25% die as enamel maturation proceeds. In this phase the Tomes'
process disappear, microvilli or brush borders appear instead.
•Maturation Proper:- massive influx of calcium and phosphates occurs and at the same
time there is selective loss of enamel proteins, mainly amelogenin and water. The
ameloblasts modulate between two phenotypes depending on the morphology of their
distal ends. The ameloblasts either have numerous microvilli forming a rumed border or
their distal ends are even (straight), thus forming two morphologically different types,
namely Rume-ended ameloblasts ( 80 % of maturation ameloblasts) and Smooth-ended
ameloblasts (20 %), respectively. The two morphological types of ameloblasts are
grouped into alternating bands during this stage, thus maturation ameloblasts modulate
i.e. change their morphology from one type to the other and back.
6. Protective stage
Ameloblasts lose their differentiation and become short cuboidal cells which together
with the remnants of the other layers of the dental organ form a multilayered structure,
namely the reduced enamel (dental) epithelium. This structure remains on the surface of
fully formed enamel until the tooth erupts. It separates the enamel from the dental sac
and thus protect it from being in contact with connective tissue cells in the dental sac. If
this contact accidentally happens, either enamel is resorbed resulting in pitting or dental
sac cells in the contact area differentiate into cementoblasts and lay down cementum on
the enamel surface. Both produce adverse (unsightly) effects on enamel appearance.
The reduced dental epithelium and the oral epithelium jointly form the dentogingival
junction of the erupting tooth.
Desmolyic stage
The reduce enamel epithelium elaborate the desomolytic enzyme to destroy connective
tissue fibers that surround the crown of the tooth to facilitate the eruption of the tooth.
After that the reduce enamel epithelia fuse with oral epithelium and form eruptive canal
from which the tooth will erupt without any bleeding.
7. Mineralization pattern of enamel:-
Mineralization starts in the oldest enamel (tip of cusp) and proceeds in 2 general
directions: spreading down along the D-E junction and progressing toward the enamel
surface. If the tooth is a multicuspid, enamel formation starts at the tip of each cusp,
spreads down and fuses at the base of the cusps in the regions of pits and fissures in
the occlusal surface of tooth.
Factors affect growth of crystals are:-
•Non collagenous protein able to bind to different surface of crystals
preventing further growth.
•Pyrophosphate inhibit further growth of crystal.
•Alkaline phosphatase enzyme is associated with production of any
mineralized tissue, it is involved with blood vessels and cell membrane
of ameloblasts. Alkaline phosphatase activity breaks down
pyrophosphate, thereby permitting crystal growth to proceed.
8. Defects of amelogensis
•Defect in enamel can be caused by febrile disease resulting in distinctive
bands of malformed enamel.
•Defects can be formed by tetracycline induced disturbances in teeth.
Tetracycline antibiotics are incorporated into mineralizing tissues, in case
of enamel, this incorporation may result in a band of brown pigmentation
or even total pigmentation, hypoplasia or absences of enamel also may
occur.
•Fluoride ions can interfere with amelogensis. chronic ingestion of
fluoride ion concentrations in excess of 5ppm (5 times the amount in
fluoridated water supplies) interferes sufficiently with ameloblast
function to produce mottled enamel, mottled enamel is seen as white
patches of hypo mineralized and altered enamel.